Heads up: There are no amended sections in this chapter.
|Adopt entire chapter||X|
|Adopt entire chapter as |
amended (amendedsections listed below)
|Adopt only those sections |
that are listed below
|Chapter / Section|
The state agency does not adopt sections identified with the following symbol: †
The Office of the State Fire Marshal's adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
|SPILL CLASSIFICATION||EXPOSED TOTAL VOLUME OF OIL (VT) (bbls)||MAXIMUM NUMBER OF TRANSFERS PER BERTHING SYSTEM PER YEAR||MAXIMUM VESSEL SIZE (DWT×1,000)|
|Moderate||< 1200||≥ 90||≥ 30|
|Low||< 1200||< 90||< 30|
The Lempert-Keene-Seastrand oil spill prevention and response act of 1990 (act), as amended, authorizes the California State Lands Commission (SLC) to regulate marine terminals, herein referred to as marine oil terminals (MOTs), in order to protect public health, safety and the environment. The authority for this regulation is contained in Sections 8750 through 8760 of the California Public Resources Code. This act defines "oil" as any kind of petroleum, liquid hydrocarbons, or petroleum products or any fraction or residues thereof, including but not limited to, crude oil, bunker fuel, gasoline, diesel fuel, aviation fuel, oil sludge, oil refuse, oil mixed with waste and liquid distillates from unprocessed natural gas. The provisions of this chapter regulate onshore and offshore MOTs as defined under this act, including marine terminals that transfer liquefied natural gas (LNG).
The Marine Environmental Protection Division (Division) administers this code on behalf of the SLC.
The purpose of this code is to establish minimum engineering, inspection and maintenance criteria for MOTs in order to prevent oil spills and to protect public health, safety and the environment. This code does not specifically address terminal siting, systems onboard vessels, processing facilities or operational requirements. Relevant provisions from existing codes, industry standards, recommended practices, regulations and guidelines have been incorporated directly or through reference, as part of this code.
Where there are differing requirements between this code and/or references cited herein, the choice of application shall be subject to Division approval.
In circumstances where technologies proposed for use are not covered by this code and/or references cited herein, prevention of oil spills and equivalent or better protection of the public health, safety and the environment must be demonstrated, and the choice of application shall be subject to Division approval.
The provisions of this chapter are applicable to the evaluation of existing MOTs and design of new MOTs in California. Each provision is classified as New (N), Existing (E), or Both (N/E) and shall be applied accordingly. If no classification is indicated, the classification shall be considered to be (N/E).
Existing (E) requirements apply to MOTs that were in operation on the date this code became effective (February 6, 2006). For these MOTs, equivalent or in-kind replacement of existing equipment, short pipeline sections or minor modification of existing components shall also be subject to the existing (E) requirements.
New (N) requirements apply to:
- A MOT or berthing system (Subsection 3102F.1.3) that commences or recommences operation with a new or modified operations manual after adoption of this code.
- Addition of new structural components or systems at an existing MOT that are structurally independent of existing components or systems.
- Addition of new (nonreplacement) equipment, piping, pipelines, components or systems to an existing MOT.
- Major repairs or substantially modified in-place systems.
- Any associated major installations or modifications.
This Code ensures that a MOT can be safely operated within its inherent structural and equipment-related constraints.
Section 3102F defines minimum requirements for audit, inspection and evaluation of the structural, electrical and mechanical systems on a prescribed periodic basis, or following a significant, potentially damage-causing event.
Section 3103F, 3104F and 3107F provide criteria for structural loading, deformation and performance-based evaluation considering earthquake, wind, wave, current, seiche and tsunami effects.
Section 3105F provides requirements for the safe mooring and berthing of tank vessels and barges.
Section 3106F describes requirements for geotechnical hazards and foundation analyses, including consideration of slope stability and soil failure.
Section 3108F provides requirements for fire prevention, detection and suppression including appropriate water and foam volumes.
Sections 3109F through 3111F provide requirements for piping/ pipelines, mechanical and electrical equipment and electrical systems.
Section 3112F provides requirements specific to marine terminals that transfer LNG.
Generally, English units are typically prescribed herein; however, System International (SI) units are utilized in Section 3112F and in many of the references.
Each MOT shall utilize up-to-date Risk and Hazards Analysis results developed per CCPS "Guidelines for Hazard Evaluation Procedures" [1.1] and [1.2], to identify the hazards associated with operations at the MOT, including operator error, the use of the facility by various types of vessels (e.g., multi-use transfer operations), equipment failure and external events likely to cause an oil spill.
If there are changes made to the built MOT or subsequently any new hazard is identified with significant impact, the updated Risk and Hazards Analysis shall be used.
Assessed magnitude of potential oil spill releases and consequences shall be mitigated by implementing appropriate designs using best achievable technologies, subject to Division approval. The residual risks are addressed by operational and administrative means via 2 CCR 2385 [1.3].
Risk and Hazards Analysis requirements specific to marine terminals that transfer LNG are discussed in Section 3112F.2.
Each MOT shall be categorized into one of three oil spill exposure classifications (high, medium or low) as shown in Table 31F-1-1, based on all of the following:
- Exposed total volume of oil (VT) during transfer.
- Maximum number of oil transfer operations per berthing system (defined in Section 3102F.1.3) per year.
- Maximum vessel size (DWT capacity) that may call at the MOT.
During a pipeline leak, a quantity of oil is assumed to spill at the maximum cargo flow rate until the ESD is fully effective. The total volume (VT) of potential exposed oil is equal to the sum of the stored and flowing volumes (Vs + VF) at the MOT, prior to the emergency shutdown (ESD) system(s) stopping the flow of oil. All potential spill scenarios shall be evaluated and the governing scenario clearly identified. The stored volume (Vs) is the non-flowing oil. The flowing volume (VF) shall be calculated as follows:
VF = Flowing volume of potential exposed oil [bbl]
QC = Maximum cargo transfer rate [bbl/hr]
Δt = For MOTs that first transferred oil on or before January 1, 2017, Δt may be taken as (ESD time, 30 or 60 seconds). For MOTs that first transfer oil after January 1, 2017, Δt shall be taken as ((ESD closure time) + (time required to activate ESD)) [seconds].
If spill reduction strategies, (e.g. pipeline segmentation devices, system flexibility and spill containment devices) are adopted, such that the maximum volume of exposed oil during transfer is less than 1,200 barrels, the spill classification of the facility may be lowered.
This classification does not apply to marine terminals that transfer LNG.
Whenever physical changes are made to the built MOT that significantly impact operations, a Management of Change (MOC) process shall be followed per Section 6.6 of API Standard 2610 [1.4].
All audits, inspections, engineering analyses or design shall be reviewed by a professional having similar or higher qualifications as the person who performed the work, to ensure quality assurance. This review may be performed in-house and shall include a concluding statement of compliance with this code.
The Division may require peer review of advanced engineering analyses and designs, including, but not limited to, nonlinear dynamic structural analyses, alternative lateral force procedures, complex geotechnical evaluations, subsea pipeline analyses and designs and fatigue analyses. Peer review shall be performed by an external independent source to maintain the integrity of the process.
The peer reviewer(s) and their affiliated organization shall have no other involvement in the project, except in a review capacity. The peer reviewer(s) shall be a California registered engineer(s) familiar with regulations governing the work and have technical expertise in the subject matter to a degree of at least that needed for the original work. The peer reviewer(s)' credentials shall be presented to the Division for approval prior to commencement of the review.
Upon completion of the review process, the peer reviewer(s) shall submit a written report directly to the Division that covers all aspects of the review process, including, but not limited to:
- Scope, extent and limitations of the review.
- Status of the documents reviewed at each stage (i.e. revision number and date).
- Recommended corrective actions and resolutions, if necessary.
- Certification by the peer reviewer(s), including whether or not the final reviewed work meets the requirements of this code.
- Formal documentation of important peer review correspondence, including requests for information and written responses.
The following will be subject to review for compliance with this code by the Division or its authorized representative(s):
- Any audit, inspection, analysis or evaluation of MOTs.
- Any significant change, modification or re-design of a structural, mooring, fire, piping/pipelines, mechanical or electrical system at an MOT, prior to use or reuse.
- Engineering analysis and design for any new MOT prior to construction. Also see Section 3102F.3.3.1.
- Construction inspection team and the construction inspection report(s).
In special circumstances where certain requirements of these standards cannot be met, alternatives that provide an equal or better protection of the public health, safety and the environment shall be subject to Division Chief approval with concurrence of the Division's lead engineer in responsible charge.
|DWT||=||Dead weight tonnage|
|QC||=||Maximum cargo transfer rate [bbl/hr]|
|VF||=||Flowing volume of potential exposed oil [bbl]|
|VS||=||Stored volume of potential exposed oil [bbl]|
|VT||=||Total volume of potential exposed oil [bbl]|
|Δt||=||ESD closure and activation time (if applicable) [sec]|
[1.1] Center for Chemical Process Safety (CCPS), 2008, "Guidelines for Hazard Evaluation Procedures", 3rd ed., New York.
[1.2] California Code of Regulations (CCR), Title 14, Division 1, Chapter 3, Oil Spill Contingency Plans (14 CCR 815.01 through 818.03), Section 817.02(c)(1) — Risk and Hazard Analysis.
[1.3] California Code of Regulations (CCR), Title 2, Division 3, Chapter 1, Article 5 — Marine Terminals Inspection and Monitoring (2 CCR 2300 et seq.)
[1.4] American Petroleum Institute (API), 2005, API Standard 2610 (R2010), "Design, Construction, Operation, Maintenance, and Inspection of Terminal and Tank Facilities," 2nd ed., Washington, D.C.
Authority: Sections 8750 through 8760, Public Resources Code.
Reference: Sections 8750, 8751, 8755 and 8757, Public Resources Code. Section 8670.28(a)(7), Government Code.
MAXIMUM INTERVAL BETWEEN UNDERWATER INSPECTIONS (YEARS)1
|CONSTRUCTION MATERIAL||CHANNEL BOTTOM
|Unwrapped Timber or Unprotected Steel
(no coating or cathodic protection)4
|Concrete, Wrapped Timber, Protected Steel
or Composite Materials (FRP, plastic, etc.)4
- The maximum interval between Underwater Inspections shall be changed as appropriate, with the approval of the Division, based on the extent of deterioration observed on a structure, the rate of further anticipated deterioration or other factors.
- Benign environments include fresh water and maximum current velocities less than 1.5 knots for the majority of the days in a calendar year.
- Aggressive environments include brackish or salt water, polluted water or waters with current velocities greater than 1.5 knots for the majority of the days in the calendar year.
- For most structures, two maximum intervals will be shown in this table, one for the assessment of construction material (timber, concrete, steel, etc.) and one for scour (last 2 columns). The shorter interval of the two should dictate the maximum interval used.
- MOTs rated "Critical" will not be operational; and Emergency Action shall be required in accordance with Table 31F-2-6.
- ICARs shall be assigned in accordance with Table 31F-2-4.
UNDERWATER INSPECTION LEVELS OF EFFORT [2.2]
|I||General visual/tactile inspection to confirm as-built condition and detect severe damage||Extensive corrosion, holes
Severe mechanical damage
|Major spalling and cracking
Severe reinforcement corrosionBroken piles
|Major loss of section
Broken piles and bracingsSevere abrasion or marine borer attack
Broken pilesMajor cracking or mechanical damage
|II||To detect surface defects normally obscured by marine growth||Moderate mechanical damage
Corrosion pitting and loss of section
|Surface cracking and spalling
Rust stainingExposed reinforcing steel and/or prestressing strands
|External pile damage due to marine borers
Splintered pilesLoss of bolts and fasteners
Rot or insect infestation
|III||To detect hidden or interior damage, evaluate loss of cross-sectional area or evaluate material homogeneity||Thickness of material
Electrical potentials for cathodic protection
|Location of reinforcing steel
Beginning of corrosion of reinforcing steelInternal voids
Change in material strength
|Internal damage due to marine borers (internal voids)
Decrease in material strength
SCOPE OF UNDERWATER INSPECTION [2.2]
|LEVEL||SAMPLE SIZE AND METHODOLOGY1|
|II||Sample Size:||10%||Every 100 LF||10%||Every 100 LF||10%||Every 50 LF||10%||As necessary|
|Method:||Visual: Removal of marine growth in 3 bands||Visual: Removal of marine growth in 1 SF areas||Visual: Removal of marine growth in 3 bands||Visual: Removal of marine growth in 1 SF areas||Visual: Removal of marine growth on 3 bands Measurement: Remaining diameter||Visual: Removal of marine growth in 1 SF areas||Visual: Removal of marine growth in 3 bands|
|III||Sample Size:||5%||Every 200 LF||0%||0%||5%||Every 100 LF||0%||Sonar imaging as necessary|
|Method:||Remaining thickness measurement; electrical potential measurement; corrosion profiling as necessary||Remaining thickness measurement; electrical potential measurement; corrosion profiling as necessary||N/A||N/A||Internal marine borer infestation evaluation||Internal marine borer infestation evaluation|
1. The minimum inspection sampling size for small structures shall include at least two components.
LF = Linear Feet; SF = Square Feet; N/A = Not Applicable
|RATING||DESCRIPTION OF STRUCTURE(S) AND/OR SYSTEMS4|
|OSAR1 and SSAR2||ICAR3|
|6||Good||The capacity of the structure or system meets the requirements of this standard.||No problems or only minor problems noted. Structural elements may show very minor deterioration, but no overstressing observed.|
|The structure or system should be considered fit-for-purpose. No repairs or upgrades are required.||No repairs or upgrades are required.|
|5||Satisfactory||The capacity of the structure or system meets the requirements of this standard.||Limited minor to moderate defects or deterioration observed, but no overstressing observed.|
|The structure or system should be considered fit-for-purpose. No repairs or upgrades are required.||No repairs or upgrades are required.|
|4||Fair||The capacity of the structure or system is no more than 15 percent below the requirements of this standard, as determined from an engineering evaluation.||All primary structural elements are sound, but minor to moderate defects or deterioration observed. Localized areas of moderate to advanced deterioration may be present, but do not significantly reduce the load bearing capacity of the structure.|
|The structure or system should be considered as marginal. Repair and/or upgrade measures may be required to remain operational. Facility may remain operational, provided a plan and schedule for remedial action is presented to and accepted by the Division.||Repair and/or upgrade measures may be required to remain operational. Facility may remain operational, provided a plan and schedule for remedial action is presented to and accepted by the Division.|
|3||Poor||The capacity of the structure or system is no more than 25 percent below the requirements of this standard, as determined from an engineering evaluation.||Advanced deterioration or overstressing observed on widespread portions of the structure, but does not significantly reduce the load bearing capacity of the structure.|
|The structure or system is not fit-for-purpose. Repair and/or upgrade measures may be required to remain operational. The facility may be allowed to remain operational on a restricted or contingency basis until the deficiencies are corrected, provided a plan and schedule for such work is presented to and accepted by the Division.||Repair and/or upgrade measures may be required to remain operational. The facility may be allowed to remain operational on a restricted or contingency basis until the deficiencies are corrected, provided a plan and schedule for such work is presented to and accepted by the Division.|
|2||Serious||The capacity of the structure or system is more than 25 percent below the requirements of this standard, as determined from an engineering evaluation.||Advanced deterioration, overstressing or breakage may have significantly affected the load bearing capacity of primary structural components. Local failures are possible and loading restrictions may be necessary.|
|The structure or system is not fit-for-purpose. Repairs and/or upgrade measures may be required to remain operational. The facility may be allowed to remain operational on a restricted basis until the deficiencies are corrected, provided a plan and schedule for such work is presented to and accepted by the Division.||Repairs and/or upgrade measures may be required to remain operational. The facility may be allowed to remain operational on a restricted basis until the deficiencies are corrected, provided a plan and schedule for such work is presented to and accepted by the Division.|
|1||Critical||The capacity of the structure or system is critically deficient relative to the requirements of this standard.||Very advanced deterioration, overstressing or breakage has resulted in localized failure(s) of primary structural components. More widespread failures are possible or likely to occur and load restrictions should be implemented as necessary.|
|The structure or system is not fit-for-purpose. The facility shall cease operations until deficiencies are corrected and accepted by the Division.||The facility shall cease operations until deficiencies are corrected and accepted by the Division.|
- OSAR = Operational Structural Assessment Ratings
- SSAR = Seismic Structural Assessment Ratings
- ICAR = Inspection Condition Assessment Ratings [2.2]; Ratings shall be assigned comparing the observed condition to the as-built condition.
- Structural, mooring or berthing systems
COMPONENT DEFICIENCY REMEDIAL ACTION PRIORITIES (RAP)
|REMEDIAL PRIORITIES||DESCRIPTION AND REMEDIAL ACTIONS|
Specified whenever a condition that poses an immediate threat to public health, safety or the environment is observed. Emergency Actions may consist of barricading or closing all or portions of the berthing system, evacuating product lines and ceasing transfer operations.
The berthing system is not fit-for-purpose. Immediate remedial actions are required prior to the continuance of normal operations.
Specified whenever defects or deficiencies pose a potential threat to public health, safety and the environment. Actions may consist of limiting or restricting operations until remedial measures have been completed.
The berthing system is not fit-for-purpose. This priority requires investigation, evaluation and urgent action.
Specified whenever systems require upgrading in order to comply with the requirement of these standards or current applicable codes. These deficiencies do not require emergency or urgent actions.
The MOT may have limitations placed on its operational status.
Specified whenever damage or defects requiring repair are observed.
Recommended action is a good engineering/maintenance practice, but not required by these standards.
The berthing system is fit-for-purpose.
|Emergency Action||Specified whenever a condition which poses an immediate threat to public health, safety or the environment is observed. Emergency Actions may consist of barricading or closing all or portions of the berthing system, limiting vessel size, placing load restrictions, evacuating product lines, ceasing transfer operations, etc.|
|Engineering Evaluation||Specified whenever damage or deficiencies are observed which require further investigation or evaluation to determine appropriate follow-up actions.|
|Repair Design Inspection||Specified whenever damage or defects requiring repair are observed. The repair design inspection is performed to the level of detail necessary to prepare appropriate repair plans, specifications and estimates.|
|Upgrade Design and Implementation||Specified whenever the system requires upgrading in order to comply with the requirements of these standards and current applicable codes.|
|Special Inspection||Typically specified to determine the cause or significance of nontypical deterioration, usually prior to designing repairs. Special testing, laboratory analysis, monitoring or investigation using nonstandard equipment or techniques are typically required.|
|Develop and Implement Repair Plans||Specified when the Repair Design Inspection and required Special Inspections have been completed. Indicates that the structure is ready to have repair plans prepared and implemented.|
|No Action||Specified when no further action is necessary until the next scheduled audit or inspection.|
|EXAMPLE||EXECUTIVE SUMMARY TABLE (ES-1A)
GLOBAL OPERATIONAL STRUCTURAL ASSESSMENT RATINGS (OSAR)
audit due date(MM/YYYY)
|North Wharf||Berth 1||Wharfhead||O||5||08/2008||08/2011||02/2008||N/A||Y||None|
|North Wharf||Berth 1||Mooring Dolphin||M||3||08/2008||08/2011||05/2008||12/2008||N||Hook capacity inadequate|
|North Wharf||Berth 1||Breasting Dolphin||B||2||08/2008||08/2011||06/2008||02/2010||N||Berthing velocity restrictions required. Velocity monitoring system operational. Fender system to be upgraded.
See Terminal Operating Limits.
|North Wharf||Berth 1||Overall||O||4||08/2008||08/2011||02/2008||N/A||Y||None|
|North Wharf||Berth 1||Dolphins, Trestles, Catwalks, Bulkhead walls, etc.||08/2008||08/2011|
|South Wharf||Berth 2||08/2008||08/2011|
|EXAMPLE||EXECUTIVE SUMMARY TABLE (ES-1B)
GLOBAL SEISMIC STRUCTURAL ASSESSMENT RATINGS (SSAR)
audit due date(MM/YYYY)
|Berth 1||Wharfhead||2||08/2008||08/2011||05/2008||02/2010||N||Level 1 — OK; SAP2000 Pushover Analysis
Level 2 — NG; SAP2000 Pushover Analysisdisplacements too large and liquefaction
|Berth 1||Trestle||5||08/2008||08/2011||05/2008||N/A||Y||Level 1 — OK; SAP2000 Linear Analysis
Level 2 — OK; SAP2000 Linear Analysis
|Berth 1||30" Crude line||5||08/2008||08/2011||05/2008||N/A||Y||Level 1 — N/A
Level 2 — OK; CAESAR Analysis
|EXAMPLE||EXECUTIVE SUMMARY TABLE (ES-1C)
GLOBAL INSPECTION CONDITION ASSESSMENT RATINGS (ICAR)8
|North Wharf||Berth 1||Wharfhead||AW||5||02/2008||3||02/2011||General satisfactory condition.
See RAPs in Table ES-2 for details.
|North Wharf||Berth 1||Wharfhead||UW||4||02/2008||5||02/2013||Pile damage; 10 serve, 15 minor
See RAPs in Table ES-2 for details.
|North Wharf||Berth 1||Breasting
|AW||6||02/2008||3||02/2011||See RAPs in Table ES-2|
|North Wharf||Berth 1||Breasting
|UW||5||02/2008||5||02/2013||See RAPs in Table ES-2|
|North Wharf||Berth 1||Dolphins,
|South Wharf||Berth 2|
- The term "Overall" shall be input in this field when the assessment ratings are summarized for a berth.
- "Types of Analyses": "O" = Operational Loading Analysis, "M" = Mooring Analysis, "B" = Berthing Analysis
- "Types of Inspections": "AW" = Above Water Inspection, "UW" = Underwater Inspection
- All assessment ratings shall be assigned in accordance with Table 31F-2-4.
- The "Analysis Dates" are defined by the month and year in which the final design package is submitted to the Division.
- The "Repair/Replacement Dates" are defined by the month and year in which the repair/replacement is to be completed and operational.
- The "Description or Comments" shall reference all MOT operating limits. For OSARs, this includes berthing velocity restrictions, load limits, etc. For SSARs, this includes a brief list of the findings for each Seismic Performance Level.
- Inspection findings may trigger a structural reassessment (see Tables 31F-2-7A and 31F-2-7B).
- Ratings shall be assigned comparing the observed condition to the as-built condition.
- The "Inspection Dates" are defined by the month and year in which the last day of formal field inspection is conducted.
|EXAMPLE||EXECUTIVE SUMMARY TABLE (ES-2)
COMPONENT DEFICIENCY REMEDIAL ACTION PRIORITIES (RAP)1
|North Wharf||Berth 1||Wharfhead||02.0001.001||Piles: 10 piles have severe damage; 15 piles have minor damage.||P2||3102F.3.5.2||Replace 10 severe piles. Monitor 15 minor piles.||Y||05/2008||04/2008||10 piles replaced|
|North Wharf||Berth 1||Mooring Dolphin MD-1||02.0001.002||Curb: Spalling of concrete curb w/o exposed reinforcement.||R||3102F.3.5.2||Repair concrete curbs.||N||02/2009|
|North Wharf||Berth 1||Wharfhead||08.0001.002||International Shore Fire Connection: Connections available, but not connected.||P3||3108F.6.3.4||8.6.22||Install International Shore Fire Connections.||N||10/2008|
|North Wharf||Berth 1||Wharfhead||11.0001.001||Conduit Seals near Manifold: Conduit seals inadequate for Class 1, Division 1 location.||P1||3111F.2||Replace conduit seals with seals adequate for Class 1. Division 1 location within 30 days.||Y||04/2008||04/2008||Seals replaced|
|North Wharf||Berth 1||Wharfhead||11.0001.001||Pressurized Instrumentation Panel near Shelter: Pressure gauge reads "low" and will not hold pressure in Class 1, Division 2 location.||P2||3111F.2||3111F.4.5||Repair pressurized instrumentation panel in Class 1, Division 2 Location within 60 days.||Y||05/2008||05/2008||Pressurized instrumentation panel could not be repaired and was replaced.|
These notes apply to Table 31F-2-8:
- After a deficiency is corrected/completed, the row of text corresponding to that deficiency may be grayed out in subsequent ES-2 tables, and removed entirely in the subsequent audit.
- The "Deficiency Item Labels" shall be assigned in the format shown above with the first series of numbers representing the Code Division/Section number ("XX"), a period (".") for separation, the second series of numbers representing the deficiency item number ("XXXX"), a period (".") for separation, and the third series of numbers representing the ES-2 table revision number ("XXX") in which the deficiency was first reported. Note that the deficiency item numbering will start from "0001" for the first deficiency in each section of the audit, and will increase consecutively in all future ES-2 tables.
- RAPs shall be assigned in accordance with Table 31F-2-5.
- Professional engineering review required in accordance with Section 3102F.3.8 under "Follow-up Actions."
POST-EVENT RATINGS AND REMEDIAL ACTIONS [2.2]
|RATING||SUMMARY OF DAMAGE||REMEDIAL ACTIONS|
|A||No significant event-induced damage observed.||No further action required. The berthing system may continue operations.|
|B||Minor to moderate event-induced damage observed but all primary structural elements and electrical/mechanical systems are sound.||Repairs or mitigation may be required to remain operational. The berthing system may continue operations.|
|C||Moderate to major event-induced damage observed which may have significantly affected the load bearing capacity of primary structural elements or the functionality of key electrical/mechanical systems.||Repairs or mitigation may be necessary to resume or remain operational. The berthing system may be allowed to resume limited operations.|
|D||Major event-induced damage has resulted in localized or widespread failure of primary structural components; or the functionality of key electrical/mechanical systems has been significantly affected. Additional failures are possible or likely to occur.||The berthing system may not resume operations until the deficiencies are corrected.|
Section 3102F defines minimum requirements for audit, inspection and evaluation of the structural, mechanical and electrical components and systems.
The audit and inspections described in this Chapter (31F) are:
- Annual compliance inspection
- Post-event inspection
Each has a distinct purpose and is conducted either at a defined interval (see Table 31F-2-1 and Section 3102F.3.3), for a significant change in operations, or as a result of a significant, potentially damage-causing event. In the time between audits and inspections, operators are expected to conduct periodic walk-down examinations of the MOT to detect potentially unsafe conditions.
For the purpose of assigning structural ratings and documenting the condition of mechanical and electrical systems, an MOT shall be divided into independent "berthing systems." A berthing system consists of the wharf and supporting structure, mechanical and electrical components that serve the berth and pipeline systems.
For example, a MOT consisting of wharves with three berths adjacent to the shoreline could contain three independent "berthing systems" if the piping does not route through adjacent berths. Therefore, a significant defect that would restrict the operation of one berth would have no impact on the other two berths. Conversely, if a T-head Pier, with multiple berths sharing a trestle that supports all piping to the shoreline, had a significant deficiency on the common trestle, the operation of all berths could be adversely impacted. This configuration is classified as a single berthing system.
The physical boundaries of a berthing system may exclude unused sections of a structure. Excluded sections must be physically isolated from the berthing system. Expansion joints may provide this isolation.
All MOTs shall have records reflecting current, "as-built" conditions for all berthing systems. Records shall include, but not be limited to modifications and/or replacement of structural components, electrical or mechanical equipment or relevant operational changes, new construction including design drawings, calculations, engineering analyses, soil borings, equipment manuals, specifications, shop drawings, technical and maintenance manuals and documents.
Chronological records and reports of annual inspections, audits and post-event inspections and documentation of equipment or structural changes shall be maintained.
Records shall be indexed and be readily accessible to the Division (see 2 CCR Section 2320 (c) (2)) [2.1].
If "as-built" or subsequent modification drawings are not available, incomplete or inaccurate, a baseline inspection is required to gather data in sufficient detail for adequate evaluation.
The level of detail required shall be such that structural member sizes, connection and reinforcing details are documented, if required in the structural analysis. In addition, the strength and/or ductility characteristics of construction materials shall be determined, as appropriate. Nondestructive testing, partially destructive testing and/or laboratory testing methods may be used.
All fire, piping, mechanical and electrical systems shall be documented as to location, capacity, operating limits and physical conditions in the equipment layout diagram(s).
The Division may carry out annual inspections to determine the compliance status of the MOT with this code, based on the terminal's audit and inspection findings and action plan implementation (see Section 3102F.3.9).
These inspections may include a visual and tactile assessment of structural, mechanical and electrical systems of the topside and underside areas of the dock, including the splash zone. Subject to operating procedures, a boat shall be provided to facilitate the inspection of the dock undersides and piles down to the splash zone.
The objective of the audit is to review structural, mechanical and electrical systems on a prescribed periodic basis to verify that each berthing system is fit for its specific defined purpose. The audit includes above water and underwater inspections, engineering evaluation, documentation and recommended follow-up actions.
The audit shall include above water and underwater inspections, and structural, electrical and mechanical systems evaluations, with supporting documentation, drawings and follow-up actions. Structural systems shall include seismic, operational, mooring, berthing and geotechnical considerations. Mechanical systems shall include fire, piping/pipelines and mechanical equipment considerations. The audit is performed by a multidisciplinary team of engineers, qualified inspectors and may include Division representatives.
The above water inspection involves an examination of all structural, mechanical and electrical components above the waterline. Structural defects and their severity shall be documented, but the exact size and location of each deficiency is typically not required.
The underwater inspection involves an examination of all structural, mechanical and electrical components below the waterline. A rational and representative underwater sampling of piles may be acceptable with Division approval, for cases of limited visibility, heavy marine growth, restricted inspection times because of environmental factors (currents, water temperatures, etc.) or a very large number of piles.
Global operational structural assessment rating(s) (OSAR), global seismic structural assessment rating(s) (SSAR) and global inspection condition assessment rating(s) (ICAR) shall be assigned to each structure and overall berthing system, where appropriate (Table 31F-2-4).
Remedial action priorities (RAP) shall be assigned for component deficiencies (Table 31F-2-5). Recommendations for remediation and/or upgrading shall be prescribed as necessary.
An audit is not considered complete until the audit report is received (in electronic and hard copy formats) by the Division.
For a new MOT or new berthing system(s), the initial audit of the "as-built" systems(s) shall be performed prior to commencement of operations.
A subsequent audit of each terminal shall be completed concurrently with the inspections (see Section 3102F.3.5). The audit team leader shall recommend either: (1) a default subsequent audit interval of 4 years, or (2) an alternate interval, based on assessments of the structural, mechanical and electrical systems, and consideration of:
- The extent of the latest deterioration and/or disrepair,
- The rate of future anticipated deterioration and/or disrepair,
- The underwater inspection guidance provided in Table 31F-2-1, and
- Other specified factors.
Based on independent assessment of these factors, the Division may accept the audit team leader's recommendation or require a different subsequent audit interval.
If there are no changes in the defined purpose (see Section 3102F.3.6.1) of the berthing system(s), relevant prior analyses may be referenced. However, if there is a significant change in the operations or condition of berthing system(s), a new analysis may be required.
The Division may require an audit, inspection or supplemental evaluations to justify changes in the use of the berthing system(s).
The audit shall be conducted by a multidisciplinary team under the direction of a project manager representing the MOT. The project manager shall have specific knowledge of the MOT and may serve other roles on the audit team.
The audit team leader shall lead the on-site audit team and shall be responsible for directing field activities, including the inspection of all structural, mechanical and electrical systems. The team leader shall be a California registered civil or structural engineer and may serve other roles on the audit team.
The structural inspection shall be conducted under the direction of a registered civil or structural engineer.
All members of the structural inspection team shall be graduates of a 4-year civil/structural engineering, or closely related (ocean/coastal) engineering curriculum, and shall have been certified as an Engineer-in-Training; or shall be technicians who have completed a course of study in structural inspections. The minimum acceptable course in structural inspections shall include 80 hours of instruction specifically related to structural inspection, followed by successful completion of a comprehensive examination. An example of an acceptable course is the U.S. Department of Transportation's "Safety Inspection of In- Service Bridges." Certification as a Level IV Bridge Inspector by the National Institute of Certification in Engineering Technologies (NICET) shall also be acceptable [2.2].
For underwater inspections, the registered civil or structural engineer directing the underwater structural inspection shall also be a commercially trained diver or equivalent and shall actively participate in the inspection, by personally conducting a minimum of 25 percent of the underwater examination [2.2].
Each underwater team member shall also be a commercially trained diver, or equivalent. Divers performing manual tasks such as cleaning or supporting the diving operation, but not conducting or reporting on inspections, may have lesser technical qualifications [2.2].
A California registered civil or structural engineer shall be in responsible charge of the structural evaluations.
A registered electrical engineer shall direct the on-site team performing the inspection and evaluation of electrical components and systems.
The corrosion specialist shall be a chemical engineer, corrosion engineer, chemist or other professional with expertise in the types and causes of corrosion, and available means to prevent, monitor and mitigate associated damage. The specialist shall perform the corrosion assessment (Section 3102F.3.6.5) and may be directly involved in corrosion inspection (Section 3102F.3.5.4).
A California registered civil engineer with a California authorization as a geotechnical engineer shall perform the geotechnical evaluation required for the audit and all other geotechnical evaluations.
The Division representative(s) may participate in any audit or inspection as observer(s). The Division shall be notified in advance of audit-related inspections.
The above water inspection shall include all accessible components above and below deck that are reachable without the need for excavation or extensive removal of materials that may impair visual inspection. The above water inspection shall include, but not be limited to, the following:
- Pile caps
- Deck soffit
- Retaining walls and bulkheads
- Slope protection
- Deck topsides and curbing
- Expansion joints
- Fender system components
- Dolphins and deadmen
- Mooring points and hardware
- Navigation aids
- Platforms, ladders, stairs, handrails and gangways
- Backfill (sinkholes/differential settlement)
The underwater inspection shall include all components below deck to the mudline, including the slope and slope protection, in areas immediately surrounding the MOT. The water depth at the berth(s) shall be evaluated, verifying the maximum or loaded draft specified in the MOT's Operations Manual (2 CCR 2385) [2.1].
The underwater structural inspection shall include the Level I, II and III inspection efforts, as shown in Tables 31F-2-2 and 31F-2-3. The underwater inspection levels of effort are described below, per [2.2]:
Level I—Includes a close visual examination, or a tactile examination using large sweeping motions of the hands where visibility is limited. Although the Level I effort is often referred to as a "swim-by" inspection, it must be detailed enough to detect obvious major damage or deterioration due to overstress or other severe deterioration. It should confirm the continuity of the full length of all members and detect undermining or exposure of normally buried elements. A Level I effort may also include limited probing of the substructure and adjacent channel bottom.
Level II—A detailed inspection which requires marine growth removal from a representative sampling of components within the structure. For piles, a 12-inch high band shall be cleaned at designated locations, generally near the low waterline, at the mudline, and midway between the low waterline and the mudline. On a rectangular pile, the marine growth removal should include at least three sides; on an octagon pile, at least six sides; on a round pile, at least three-fourths of the perimeter. On large diameter piles, 3 ft or greater, marine growth removal should be effected on 1 ft by 1 ft areas at four locations approximately equally spaced around the perimeter, at each elevation. On large solid faced elements such as retaining structures, marine growth removal should be effected on 1 ft by 1 ft areas at the three specified elevations. The inspection should also focus on typical areas of weakness, such as attachment points and welds. The Level II effort is intended to detect and identify damaged and deteriorated areas that may be hidden by surface biofouling. The thoroughness of marine growth removal should be governed by what is necessary to discern the condition of the underlying structural material. Removal of all biofouling staining is generally not required.
Level III—A detailed inspection typically involving nondestructive or partially-destructive testing, conducted to detect hidden or interior damage, or to evaluate material homogeneity. Level III testing is generally limited to key structural areas, areas which are suspect or areas which may be representative of the underwater structure.
For coated steel components, Level I and Level II efforts should focus on the evaluation of the integrity and effectiveness of the coating. The piles should be inspected without damaging the coating. Level III efforts should include ultrasonic thickness measurements without removal of the coating, where feasible.
For steel, concrete or timber components that have been encased, the Level I and II efforts should focus on the evaluation of the integrity of the encasement. If evidence of significant damage to the encasement is present, or if evidence of significant deterioration of the underlying component is present, then the damage evaluation should consider whether the encasement was provided for protection and/or structural capacity. Encasements should not typically be removed for an audit.
For encasements on which the formwork has been left in place, the inspection should focus on the integrity of the encasement, not the formwork. Level I and Level II efforts in such cases should concentrate on the top and bottom of the encasement. For concrete components, if deterioration, loss of bonding or other significant problems with the encasement are suspected, it may be necessary to conduct a special inspection, including coring of the encasement and laboratory evaluation of the materials.
For steel, concrete or timber components that have been wrapped, the Level I and II efforts should focus on the evaluation of the integrity of the wrap. Since the effectiveness of a wrap may be compromised by removal, and since the removal and re-installation of wraps is time-consuming, it should not be routinely done. However, if evidence of significant damage exists, or if the effectiveness of the wraps is in question, then samples should be removed to facilitate the inspection and evaluation. The samples may be limited to particular zones or portions of members if damage is suspected, based on the physical evidence of potential problems. A minimum sample size of three members should be used. A five-percent sample size, up to 30 total members, may be adequate as an upper limit.
For wrapped timber components, Level III efforts should consist of removal of the wraps from a representative sample of components in order to evaluate the condition of the timber beneath the wrap. The sample may be limited to particular zones or portions of the members if damage is suspected (e.g., at the mudline/bottom of wrap or in the tidal zone). The sample size should be determined based on the physical evidence of potential problems and the aggressiveness of the environment. A minimum sample size of three members should be used. A five-percent sample size, up to 30 total members, may be adequate as an upper limit.
The mechanical and electrical inspections shall include but not be limited to the following:
- Loading arms
- Cranes and lifting equipment, including cables
- Piping/manifolds and supports
- Oil transfer hoses
- Fire detection and suppression systems
- Vapor control system
- Sumps/sump tanks
- Vent systems
- Pumps and pump systems
- Communications equipment
- Electrical switches and junction boxes
- Emergency power equipment
- Air compressors
- Cathodic protection systems
- ESD and other control systems
All alarms, limit switches, load cells, current meters, anemometers, leak detection equipment, etc., shall be operated and/or tested to the extent feasible, to ensure proper function.
Utility, auxiliary and fire protection piping shall have external visual inspections, similar to that defined in Section 10.1 of API RP 574 [2.3] (N/E).
During each audit, a comprehensive corrosion inspection shall be performed by a qualified engineer or technician. This inspection shall include all steel and metallic components, and any installed cathodic protection system (CPS). CPS inspection during the audit is not intended to substitute for required testing and maintenance performed on a more frequent schedule per Section 3111F.10. All inspection results shall be documented, and shall be used in the corrosion assessment (Section 3102F.3.6.5).
Submerged wharf structures and associated cathodic protection equipment (if installed) shall be inspected per [2.2]. Above water structures, ancillary equipment, supports and hardware shall be visually inspected. Corrosion inspection of utility, auxiliary and fire pipelines shall be done per Section 3102F.3.5.3.
For oil pipelines in an API 570 [2.4] inspection program, a corrosion inspection is not required as part of the audit; however, the latest inspection results, calculations and conclusions shall be reviewed, and any significant results shall be included in the corrosion assessment.
The physical boundaries of the facility shall be defined by the berthing system operating limits, along with the vessel size limits and environmental conditions.
The audit shall include "Terminal Operating Limits" (TOLs) diagrams, which provide a concise statement of the purpose of each berthing system in terms of operating limits for representative vessel size ranges and mooring configurations approved to call and/or conduct transfer operations at the MOT. This description shall include, the minimum and maximum vessel sizes, including Length Overall (LOA), beam and maximum draft with associated displacement (see Figure 31F-2-1).
In establishing limits for both the minimum and maximum vessel sizes, due consideration shall be given to water depths, dolphin spacing, fender system limitations, manifold height and hose/loading arm reach, with allowances for tidal fluctuations, surge and drift.
Maximum wind, current or wave conditions, or combinations thereof, shall be clearly defined as limiting conditions for vessels at each berth, both with and without active product transfer.
The TOLs shall be explicitly presented to facilitate implementation by the MOT operator, such as through incorporation in the MOT's Operations Manual (2 CCR 2385 [2.1]). The TOLs shall allow for direct comparison of operating limits and output from monitoring systems and instrumentation (i.e., anemometers, current meters, tension monitoring systems, velocity monitoring systems). Design and implementation considerations shall include, but not be limited to:
- Units of measurement (i.e., English vs. System International units)
- Directionality (i.e., current restrictions "to", wind restrictions "from", true or magnetic north)
- Parameters of monitoring systems and instrumentation (i.e., duration/averaging of readings, elevation/depth of readings, distance/location of readings)
Mooring and berthing analyses shall be performed in accordance with Section 3105F. The analyses shall be consistent with the terminal operating limits and the structural configuration of the wharf and/or dolphins and associated hardware.
Based on inspection results, analyses and engineering judgment, mooring and berthing OSARs shall be assigned on a global basis, independently for each structure and overall berthing system. The OSARs defined in Table 31F-2-4 shall be used for this purpose. The mooring and berthing OSARs document the berthing system(s) fitness-for-purpose.
A structural evaluation, including a seismic analysis, shall be performed in accordance with Sections 3103F through 3107F. Such evaluation shall consider local or global reduction in capacity, as determined from the inspection.
Based on inspection results, structural analyses and engineering judgment, OSARs (for operational loading) and SSARs shall be assigned on a global basis, independently for each structure, structural system(s) and berthing system(s), as appropriate. The OSARs and SSARs defined in Table 31F-2-4 shall be used for this purpose and document the structural and/or berthing system(s) fitness-for-purpose.
Based on inspection results and engineering judgment, ICARs shall be assigned on a global basis, independently for each above and underwater structure, structural system and berthing system, as appropriate. The ICARs defined in Table 31F-2-4 shall be used for this purpose.
Structural component deficiencies assigned RAPs as per Table 31F-2-5 shall be considered in the OSARs, SSARs and ICARs. The assigned ratings shall remain in effect until all the significant corrective action has been completed to the satisfaction of the Division, or until completion of the next audit.
An evaluation of all mechanical and electrical systems and components shall be performed in accordance with Sections 3108F through 3111F of these standards. Forces and imposed seismic displacements resulting from the structural analysis shall be considered in the pipeline stress analyses (Section 3109F.3), and the piping/pipelines shall be assigned SSARs in Table 31F-2-7B. Mechanical and electrical component deficiencies shall be assigned ratings from Table 31F-2-5.
A comprehensive assessment shall be performed by the corrosion specialist (Section 3102F.3.4.7), to determine the existing and potential corrosion using "as-built" drawings and specifications. This assessment shall comprise all steel and metallic components, including the structure, pipelines, supports and other MOT ancillary equipment. This assessment shall also include prestressed and reinforced concrete structures.
If cathodic protection is installed to protect wharf structures and/or pipelines, the following records shall be evaluated for each system:
- CPS equipment condition and maintenance
- Impressed current readings (as applicable)
- Potential survey results
Follow-up actions per Table 31F-2-6 shall be prescribed by the audit team. Multiple follow-up actions may be assigned; however, guidance shall be provided as to the order in which the follow-up actions should be carried out.
If an assessment rating of "1", "2" or "3" (Table 31F-2-4) or a RAP of "P1" or "P2" (Table 31F-2-5) or "Emergency Action" using Table 31F-2-6, is assigned to a structure, berthing system or critical component, the Division shall be notified immediately. The Executive Summary Table ES-2 (see Example Table 31F-2-8) shall include implementation schedules for all follow-up and remedial actions. Follow-up and remedial actions and implementation schedules are subject to Division approval.
For action plan implementation between audits, see Section 3102F.3.9.
The audit reports shall be signed and stamped by the audit team leader. The inspection and other reports and drawings shall be signed and stamped by the engineers in responsible charge.
Each audit and inspection, whether partial or complete, shall be adequately documented. Partial inspections cover only specific systems or equipment examined. The resulting reports shall summarize and reference relevant previous ratings and deficiencies. Inspection reports shall be included in subsequent audits.
The contents of the audit and inspection reports for each berthing system shall, at a minimum, include the following as appropriate:
Executive summary—a concise narrative of the audit or inspection results and analyses conclusions. It shall include summary information for each berthing system, including an overview of the assigned follow-up actions. The Executive Summary Tables shall also be included (see Example Tables 31F-2-7A through 31F-2-7C and 31F-2-8).
Table of contents
Introduction—a brief description of the purpose and scope of the audit or inspection, as well as a description of the inspection/evaluation methodology used.
Existing conditions—a description, along with a summary, of the observed conditions. Subsections shall be used to describe the above water structure, underwater structure, fire, piping/pipeline, mechanical and electrical systems, to the extent each are included in the scope of the audit. Photos, plan views and sketches shall be utilized as appropriate to describe the structure and the observed conditions. Details of the inspection results such as test data, measurements data, etc., shall be documented in an appendix.
Evaluation and assessment—assessment ratings shall be assigned to all structures and/or berthing systems. Also, see Section 3102F.3.6. All supporting calculations, as-built drawings and documentation shall be included in appendices as appropriate to substantiate the ratings. However, the results and recommendations of the engineering analyses shall be included in this section. Component deficiencies shall be described and a corresponding RAP assigned.
Follow-up actions—Specific follow-up actions (Table 31F-2-6) shall be documented (Table 31F-2-8), and remedial schedules included, for each audited system. Audit team leaders shall specify which follow-up actions require a California registered engineer to certify that the completion is acceptable.
Appendices—When appropriate, the following appendices shall be included:
- Background data on the terminal - description of the service environment (wind/waves/currents), extent and type of marine growth, unusual environmental conditions, etc.
- Inspection/testing data
- Mooring and berthing analyses
- Structural and seismic analyses and calculations
- Geotechnical report
- MOT Fire Protection Assessment
- Pipeline stress and displacement analyses
- Mechanical and electrical system documentation
- Corrosion assessment
- Photographs, sketches and supporting data shall be included to document typical conditions and referenced deficiencies, and to justify the assessment ratings and the remedial action priorities RAPs assigned.
The operator is responsible for correction of deficiencies between audits. Prior to implementation, projects shall be submitted for Division review in accordance with Section 3101F.8.3. During project implementation, the Division shall be informed of any significant changes. After project completion, "as-built" documentation, including drawings, calculations and analyses, shall be submitted to the Division.
Executive Summary Tables shall be updated by the operator and submitted to the Division at least annually.
A post-event inspection is a focused inspection following a significant, potentially damage-causing event such as an earthquake, storm, vessel impact, fire, explosion, construction incident or tsunami. The primary purpose is to assess the integrity of structural, mechanical and electrical systems. This assessment will determine the operational status and/or any remedial measures required.
Notification as per 2 CCR 2325(e) [2.1] shall be provided to the local area Division field office. The notification shall include, as a minimum:
- Brief description of the event
- Brief description of the nature, extent and significance of any damage observed as a result of the event
- Operational status and any required restrictions
- Statement as to whether a Post-Event inspection will be carried out
The Division may carry out or cause to be carried out, a post-event inspection. In the interim, the Division may direct a change in the operations manual, per 2 CCR 2385 (f)(3) [2.1].
If a post-event inspection is required, an action plan shall be submitted to the Division within five (5) days after the event. This deadline may be extended in special circumstances. The action plan shall include the scope of the inspection (above water, underwater, electrical, mechanical systems, physical limits, applicable berthing systems, etc.) and submission date of the final report. The action plan is subject to Division approval.
The qualifications of the inspection team shall be the same as those prescribed in Section 3102F.3.4. Division representatives may participate in any post-event inspection, as observers, and may provide guidance.
The post-event inspection shall focus on the possible damage caused by the event. General observations of long-term or preexisting deterioration such as significant corrosion-related damage or other deterioration should be made as appropriate, but should not be the focus of the inspection. The inspection shall always include an above-water assessment of structural, mechanical and electrical components.
The inspection team leader shall determine the need for, and methodology of, an underwater structural assessment, in consultation with the Division. Above water observations, such as shifting or differential settlement, misalignments, significant cracking or spalling, bulging, etc., shall be used to determine whether or not an underwater assessment is required. Similarly, the inspection team leader shall determine, in consultation with the Division, the need for, and methodology of, any supplemental inspections (e.g., special inspections (see Section 3102F.3.5.3).
The following information may be important in determining the need for, and methodology of, the post-event inspection:
- Earthquakes or vessel or debris impact typically cause damage both above and below the waterline. Following a major earthquake, the inspection should focus on components likely to attract highest lateral loads (batter or shorter piles in the rear of the structure, etc.). In case of vessel or debris impact, the inspection effort should focus on components in the path of the impact mass.
- Major floods or tsunamis may cause undermining of the structure and/or scouring at the mudline.
- Fire damage varies significantly with the type of construction materials but all types may be adversely affected. Special inspections (sampling and laboratory testing) shall be conducted, as determined by the inspection team leader, in order to determine the nature and extent of damage.
- High wind or wave events often cause damage both above and below the waterline. An underwater inspection may be required if damage is visible above the waterline. Structural damage may be potentially increased if a vessel was at the berth during the event. The effects of high wind may be most prevalent on equipment and connections of such equipment to the structure.
The methodology of conducting an underwater post-event inspection should be established with due consideration of the structure type and type of damage anticipated. Whereas slope failures or scour may be readily apparent in waters of adequate visibility, overstressing cracks on piles covered with marine growth will not be readily apparent. Where such hidden damage is suspected, marine growth removal should be performed on a representative sampling of components in accordance with the Level II effort requirements described in Section 3102F.3.5.2. The cause of the event will determine the appropriate sample size and locations.
A post-event rating [2.2] shall be assigned to each berthing system upon completion of the inspection (see Table 31F-2-9). All observations of the above and under water structure, mechanical and electrical components and systems shall be considered in assigning a post-event rating.
Ratings should consider only damage that was likely caused by the event. Pre-existing deterioration such as corrosion damage should not be considered unless the structural integrity is immediately threatened or safety systems or protection of the environment may be compromised.
Assignment of ratings should reflect an overall characterization of the berthing system being rated. The rating shall consider both the severity of the deterioration and the extent to which it is widespread throughout the facility.
Follow-up actions shall be assigned upon completion of the post-event inspection of each berthing system. Table 31F-2-5 specifies remedial action priorities for deficiencies. Table 31F-2-6 specifies various follow-up actions. Multiple follow-up actions may be assigned; however, guidance should be provided as to the order in which the follow-up actions should be carried out. Follow-up actions shall be subject to Division approval.
Documentation of the specific attributes of each defect shall not be required during a post-event inspection. However, a narrative description of significant damage shall be used. The description shall be consistent with and shall justify the post-event rating assigned.
A report shall be prepared and submitted to the Division upon completion of the post-event inspection and shall, at a minimum, include:
- Brief description of the facility including the physical limits of the structure, type of construction material(s), and the mechanical and electrical systems present
- Brief description of the event triggering the inspection
- Scope of the inspection (above water, underwater, electrical or mechanical)
- Date of the inspection
- Names and affiliations of inspection team
- Description of the nature, extent and significance of any observed damage resulting from the event
- Photographs should be provided to substantiate the descriptions and justify the condition rating
- Assignment of a post-event rating
- Statement regarding whether the facility is fit to resume operations and, if so, under what conditions
- Assignment of follow-up action(s)
- Inspection data, drawings, calculations and other relevant engineering materials
- Signature and stamp of team leader(s)
Upon completion of all actions delineated in the action plan, a final report shall be submitted to the Division to document the work completed. Supporting documentation such as calculations or other relevant data shall be provided in appendices.
[2.1]California Code of Regulations (CCR), Title 2, Division 3, Chapter 1, Article 5 — Marine Terminals Inspection and Monitoring (2 CCR 2300 et seq.)
[2.2]Childs, K.M., editor, 2001, "Underwater Investigations - Standard Practice Manual," American Society of Civil Engineers, Reston, VA.
[2.3]American Petroleum Institute (API), 2009, API Recommended Practice 574 (API RP 574), "Inspection Practices for Piping System Components," 3rd ed., Washington, D.C.
Authority: Sections 8750 through 8760, Public Resources Code
Reference: Sections 8750, 8751, 8755 and 8757, Public Resources Code.
|MATERIAL||UNIT WEIGHT (pcf)*|
|Steel or cast steel||490|
|Concrete, reinforced (normal weight)||145-160|
|Concrete, reinforced (lightweight)||90-120|
* pounds per cubic foot
|LOCATION||AREA LOADS (psf)***|
|Areas containing equipment and piping||35**|
* Allowance for incidental items such as railings, lighting, miscellaneous equipment, etc.
**35 psf is for miscellaneous general items such as walkways, pipe supports, lighting and instrumentation. Major equipment weight shall be established and added into this weight for piping manifold, valves, deck crane, fire monitor tower, gangway structure and similar ma/or equipment.
*** pounds per square foot
VALUES OF Fa
|< 0.25||0.5||0.75||1.0||> 1.25|
VALUES OF Fv
|< 0.1||0.2||0.3||0.4||> 0.5|
VALUES OF BS AND B1 [3.2]
Note: Linear interpolation should be used for damping values not specifically listed.
|S.F. BAY LOCALE||MAXIMUM WATER
BERTHING VELOCITY Vn (NORMAL TO BERTH)1
|VESSEL SIZE (DWT)||TUG BOAT ASSISTANCE||SITE CONDITIONS|
|≤ 10,000||No||1.31 ft/sec||0.98 ft/sec||0.53 ft/sec|
|≤ 10,000||Yes||0.78 ft/sec||0.66 ft/sec||0.33 ft/sec|
|50,000||Yes||0.53 ft/sec||0.39 ft/sec||0.26 ft/sec|
|≥ 100,000||Yes||0.39 ft/sec||0.33 ft/sec||0.26 ft/sec|
- For vessel sizes not shown, interpolation between velocities may be used.
|SITE CONDITIONS||DESCRIPTION||WIND SPEED1||SIGNIFICANT WAVE HEIGHT||CURRENT SPEED2|
Strong CurrentsHigh Waves
|> 38 knots||> 6.5 ft||> 2 knots|
Moderate CurrentModerate Waves
|≥ 38 knots||≤ 6.5 ft||≤ 2 knots|
Moderate CurrentModerate Waves
|< 38 knots||< 6.5 ft||< 2 knots|
- A 30-second duration measured at a height of 33 ft.
- Taken at 0.5 x water depth
|VESSEL SIZE (DWT)||ANGLE (degrees)|
LRFD LOAD FACTORS FOR LOAD COMBINATIONS [3.18]
|Dead Load (D)||1.2||0.9||1.2||1.2||1.2 + k1||0.9-k1|
|Live Load (L)||1.6||—||1.62||1.0||1.0||—|
|Wind on Structure (W)||1.6||1.6||1.6||1.6||—||—|
|Current on Structure (C)||1.2||0.9||1.2||1.2||1.2||0.9|
|Earth Pressure on the Structure (H)||1.6||1.6||1.6||1.6||1.64||1.64|
|Mooring/Breasting Load (M)||—||—||1.6||—||—||—|
|Berthing Load (Be)||—||—||—||1.6||—||—|
|Earthquake Load (E)||—||—||—||—||1.0||1.0|
- k = 0.50 (PGA) The k factor (k=0.5(PGA)) and buoyancy (B) shall be applied to the vertical dead load (D) only, and not to the inertial mass of the structure.
- The load factor for live load (L) may be reduced to 1.3 for the maximum outrigger float load from a truck crane.
- For Level 1 and 2 earthquake conditions with strain levels defined in Division 7, the current on structure (C) may not be required.
- An earth pressure on the Structure factor (H) of 1.0 may be used for pile or bulkhead structures.
SERVICE OR ASD LOAD FACTORS FOR LOAD COMBINATIONS [3.18]
|Dead Load (D)||1.0||1.0||1.0||1 + 0.7k1||1 - 0.7k1|
|Live Load (L)||1.0||1.0||0.75||0.75||—|
|Wind on Structure (W)||1.0||1.0||0.75||—||—|
|Current on Structure (C)||1.0||1.0||1.0||—||—|
|Earth Pressure on the Structure (H)||1.0||1.0||1.0||1.0||1.0|
|Mooring/Breasting Load (M)||—||1.0||—||—||—|
|Berthing Load (Be)||—||—||1.0||—||—|
|Earthquake Load (E)||—||—||—||0.7||0.7|
|% Allowable Stress||100||100||100||1002|
- k = 0.5 (PGA)
- Increase in allowable stress shall not be used with these load combinations unless it can be demonstrated that such increase is justified by structural behavior caused by rate or duration of load. See ASCE/SEI 7 [3.21]
Dead loads shall include the weight of the entire structure, including permanent attachments such as loading arms, pipelines, deck crane, fire monitor tower, gangway structure, vapor control equipment and mooring hardware. Unit weights specified in Section 3103F.2.2 may be used for MOT structures if actual weights are not available.
The unit weights in Table 31F-3-1 may be used for both existing and new MOTs.
The earthquake ground motion parameters of peak ground acceleration, spectral acceleration and earthquake magnitude are modified for site amplification and near fault directivity effects. The resulting values are the Design Peak Ground Acceleration (DPGA), Design Spectral Acceleration (DSA) and Design Earthquake Magnitude (DEM).
For Site Classes A through E (Section 3103F.4.2.1), peak ground and design spectral accelerations shall be obtained from:
- U.S. Geological Survey (USGS) published data as discussed in Section 3103F.4.2.2, or
- A site-specific probabilistic seismic hazard analysis (PSHA) as discussed in Section 3103F.4.2.3.
Unless stated otherwise, the DSA values are for 5 percent damping; values at other levels may be obtained as per Section 3103F.4.2.9.
The appropriate probability levels associated with DPGA and DSA for different seismic performance levels are provided in Table 31F-4-1. Deterministic earthquake motions, which are used only for comparison to the probabilistic results, are addressed in Section 3103F.4.2.7.
Earthquake ground motion parameters can be obtained directly from the US Seismic Design Maps tool available at the USGS website (http://earthquake.usgs.gov) for the site condition(s) appropriate for the MOT site and the selected probability of exceedance. For this purpose, select the ASCE/SEI 41 [3.1] as the design code reference document, and specify the appropriate custom parameters, including but not limited to, location, required Probability of Exceedance (in 50 years), and appropriate Site Soil Classification(s) for the MOT site. The USGS tool directly provides the peak ground and spectral accelerations for the selected hazard level and site condition(s).
The alternative method of obtaining earthquake ground motion parameters, from the most current USGS data for selected hazard level and site condition(s), is permitted. If needed, the data for appropriate probability of exceedance may be obtained using the procedure described in Chapter 1 of FEMA 356 [3.2], and corrected for the MOT site as discussed in Section 3103F.4.2.4 or Section 3103F.4.2.5.
Site-specific Probabilistic Seismic Hazard Analysis (PSHA) shall use appropriate seismic sources and their characterization, attenuation relationships, probability of exceedance and site soil conditions. Site-specific PSHA shall be conducted by a qualified California registered civil engineer with a California authorization as a geotechnical engineer per Section 3102F.3.4.8.
If site-specific PSHA is used for Site Classes A, B, C, D or E, results from the site-specific PSHA shall be compared with those from the USGS published data as described in Section 3103F.4.2.2. If the two sets of values differ significantly, a justification for using the characterization chosen shall be provided. If DPGA and DSA from site-specific PSHA are less than 80 percent of the values from USGS data, a peer review may be required.
When the MOT site class is different from the Site Classes B to C boundary, site amplification effects shall be incorporated in peak ground accelerations and spectral accelerations. This may be accomplished using a simplified method or a site-specific evaluation (Section 3103F.4.2.5).
For a given site class, the following procedure from Chapter 1 of FEMA 356 [3.2] presents a simplified method that may be used to incorporate the site amplification effects for peak ground acceleration and spectral acceleration computed for the Site Classes B and C boundary.
- Calculate the spectral acceleration values at 0.20 and 1.0 second period:(3-1)(3-2)SS = short period (usually at 0.20 seconds) spectral acceleration value (for the boundary of Site Classes B and C) obtained using Section 3103F.4.2.2, or at the period corresponding to the peak in spectral acceleration values when obtained from Section 3103F.4.2.3S1 = spectral acceleration value (for the boundary of Site Classes B and C) at 1.0 second periodSXS = spectral acceleration value obtained using the short period Ss and factored by Table 31F-3-3 for the site class under consideration.
- PGAX, SXS and SX1 constitute three spectral acceleration values for the site class under consideration corresponding to periods of 0, SS (usually 0.2 seconds), and 1.0 second, respectively.
- The final response spectra, without consideration for near-fault directivity effects, values of Sa for the site class under consideration may be obtained using the following equations (for 5 percent critical damping):For 0 < T < 0.2T0(3-4)T = Period corresponding to calculated SaT0 = Period at which the constant acceleration and constant velocity regions of the design spectrum intersectFor 0.2T0 < T < T0(3-5)For T > T0(3-6)(3-7)The resulting PGAX is the DPGA. However, the Sa shall be modified for near-fault directivity effects, per Section 3103F.4.2.6 to obtain the final DSAs.
As an alternative to the procedure presented in Section 3103F.4.2.4, a site-specific response analysis may be performed. For Site Class F a site-specific response analysis is required. The analysis shall be either an equivalent linear or nonlinear analysis. Appropriate acceleration time histories as discussed in Section 3103F.4.2.10 shall be used.
In general, an equivalent linear analysis using, for example, SHAKE91 [3.3] is acceptable when the strength and stiffness of soils are unlikely to change significantly during the seismic shaking and the level of shaking is not large. A nonlinear analysis should be used when the strength and/or stiffness of soils could significantly change during the seismic shaking or significant nonlinearity of soils is expected because of high seismic shaking levels.
The choice of the method used in site response analysis shall be justified considering the expected stress-strain behavior of soils under the shaking level considered in the analysis.
Site-specific site response analysis may be performed using one-dimensional analysis. However, to the extent that MOTs often involve slopes or earth retaining structures, the one-dimensional analysis should be used judiciously. When one-dimensional analysis cannot be justified or is not adequate, two-dimensional equivalent linear or nonlinear response analysis shall be performed. Site-specific response analysis results shall be compared to those based on the simplified method of Section 3103F.4.2.4 for reasonableness.
When the site is 15 km (9.3 miles) or closer to a seismic source that can significantly affect the site, near-fault directivity effects shall be reflected in the spectral acceleration values and in the deterministic spectral acceleration values of Section 3103F.4.2.7.
Two methods are available for incorporating directivity effects:
- Directivity effects may be reflected in the spectral acceleration values in a deterministic manner by using well established procedures such as that described in Somerville, et al. [3.4]. The critical seismic sources and their characterization developed as part of the deterministic ground motion parameters (Section 3103F.4.2.7) should be used to evaluate the directivity effects. The resulting adjustments in spectral acceleration values may be applied in the probabilistic spectral acceleration values developed per Section 3103F.4.2.4 or 3103F.4.2.5. Such adjustment can be independent of the probability levels of spectral accelerations.
- Directivity effects may be incorporated in the results of site specific PSHA per Section 3103F.4.2.3. In this case, the directivity effects will also depend on the probability level of spectral accelerations.
Deterministic ground motions from "scenario" earthquakes may be used for comparison purposes. Deterministic peak ground accelerations and spectral accelerations may be obtained using the "Critical Seismic Source" with maximum earthquake magnitude and its closest appropriate distance to the MOT. "Critical Seismic Source" is that which results in the largest computed median peak ground acceleration and spectral acceleration values when appropriate attenuation relationships are used. The values obtained from multiple attenuation relationships should be used to calculate the median peak ground acceleration and spectral acceleration values.
For comparison, the values of peak ground accelerations and spectral accelerations may be obtained from the USGS maps, corresponding to the Maximum Considered Earthquake (MCE). In this case, the median values of peak ground acceleration and spectral acceleration values shall be 2/3 (see Section 1.6 of FEMA 356 [3.2]) of the values shown on the USGS maps.
The Design Earthquake Magnitude used in developing site-specific acceleration time histories (Section 3103F.4.2.10) or liquefaction assessment (Section 3106F.4) is obtained using either of the following two methods:
- The design earthquake may be selected as the largest earthquake magnitude associated with the critical seismic source. The distance shall be taken as the closest distance from the source to the site. The resulting design earthquake shall be associated with all DPGA values for the site, irrespective of probability levels.
- The design earthquake (DEQ) may be obtained for each DPGA or DSA value and associated probability level by determining the corresponding dominant distance and magnitude. These are the values of the distance and magnitude that contribute the most to the mean seismic hazards estimates for the probability of interest. They are usually determined by locating the summits of the 3-D surface of contribution of each small interval of magnitude and distance to the total mean hazards estimate. If this 3-D surface shows several modes with approximate weight of more than 20 percent of the total, several DEQs may be considered, and the DEQ leading to the most conservative design parameters shall be used.
Design Spectral Acceleration (DSA) values at damping other than 5 percent shall be obtained by using a procedure given in Chapter 1 of FEMA 356 [3.2], and is denoted as DSAd. The following procedure does not include near-fault directivity effects.
For 0 < T < 0.2 T0
For 0.2 T0 < T < T0
For T > T0
T = period
T0 = SX1 /SXS
BS = Coefficient used to adjust the short period spectral response, for the effect of viscous damping.
B1 = Coefficient used to adjust one-second period spectral response, for the effect of viscous damping
Values of BS and B1 are obtained from Table 31F-3-5.
Such a procedure shall incorporate the near-fault directivity effects when the MOT is 15 km (9.3 miles) or closer to a significant seismic source.
When acceleration time histories are utilized, target spectral acceleration values shall be initially selected corresponding to the DSA values at appropriate probability levels. For each set of target spectral acceleration values corresponding to one probability level, at least three sets of horizontal time histories (one or two horizontal acceleration time histories per set) shall be developed.
Initial time histories shall consider magnitude, distance and the type of fault that are reasonably similar to those associated with the conditions contributing most to the probabilistic DSA values. Preferred initial time histories should have their earthquake magnitude and distance to the seismic source similar to the mode-magnitude and mode-distance derived from the PSHA or from appropriate maps. When an adequate number of recorded time histories are not available, acceleration time histories from simulations may be used as supplements.
Scaling or adjustments, either in the frequency domain or in the time domain (preferably), prior to generating acceleration time histories should be kept to a minimum. When the target spectral accelerations include near-fault directivity effects (Section 3103F.4.2.6), the initial time histories should exhibit directivity effects.
When three sets of time histories are used in the analysis, the envelope of the spectral acceleration values from each time history shall be equal to or higher than the target spectral accelerations. If the envelope values fall below the target values, adjustments shall be made to ensure that the spectral acceleration envelope is higher than target spectral accelerations. If the envelope is not higher, then a justification shall be provided.
When seven or more sets of time histories are used, the average of the spectral acceleration values from the set of time histories shall be equal or higher than the target spectral acceleration values. If the average values fall below the target values, adjustments shall be made to ensure that average values are higher than the target spectral accelerations. If this is not the case, then an explanation for the use of these particular spectral acceleration values shall be provided.
When three sets of time histories are used in the analysis, the maximum value of each response parameter shall be used in the design, evaluation and rehabilitation. When seven or more sets of time histories are used in the analysis, the average value of each response parameter may be used.
Forces acting on a moored vessel may be generated by wind, waves, current, tidal variations, tsunamis, seiches and hydrodynamic effects of passing vessels. Forces from wind and current acting directly on the MOT structure (not through the vessel in the form of mooring and/or breasting loads) shall be determined in Section 3103F.7.
The vessel's moorings shall be strong enough to hold during all expected environmental and passing vessel conditions (see Section 3105F), while adequately accommodating changes in draft, surge, sway, yaw and tide.
Wind loads on a vessel, moored at a MOT, shall be determined using procedures described in this section. Wind speed measured at an elevation of 33 feet (10 meters) above the water surface, with duration of 30 seconds shall be used to determine the design wind speed and wind limits for moored vessels. If these conditions are not met, adjustment factors shall be applied per Sections 3103F.5.2.2.
For new MOTs, the 25-year return period shall be used to establish the design wind speed for each direction. The design wind speed is the maximum wind speed of 30-second duration used in the mooring analysis (see Section 3105F). The 30-second duration wind speed shall be determined from the annual maximum wind data. Average annual summaries cannot be used. Maximum wind speed data for a minimum of eight directions (45-degree increments) shall be obtained. If other duration wind data is available, it shall be adjusted to a 30-second duration, in accordance with Equation (3-12).
The operational condition is defined as the wind envelope in which a vessel may conduct transfer operations, as determined from the mooring analysis (Section 3105F). Transfer operations shall cease when the wind exceeds the maximum velocity of the envelope.
The survival condition is defined as the state wherein a vessel can remain safely moored at the berth during severe winds; however, loading arms and hoses shall be disconnected (see Sections 3110F.2 and 3110F.3 regarding movement limits of loading arms and hoses, respectfully). The survival condition is the wind zone between the operational condition and the departure condition (defined in Section 3103F.5.2.2). In this wind zone, the vessel must prepare to depart the berth.
The departure condition is defined as the wind state above which a vessel can no longer remain safely moored at the berth during severe winds, as determined from the mooring analysis (Section 3105F). For a new MOT, the departure condition threshold is the maximum wind velocity, for a 30-second gust and a 25-year return period, obtained from historical data. If the wind rises above these levels, the vessel must depart the berth.
Wind speed measured at an elevation of 33 feet (10 meters) above the water surface, with duration of 30 seconds shall be used to determine the design wind speed. If these conditions are not met, the following corrections shall be applied.
The correction for elevation is obtained from the equation:
Vw = wind speed at elevation 33 ft. (10 m.)
Vh = wind speed at elevation h
h = elevation above water surface of wind data [feet]
The available wind duration shall be adjusted to a 30-second value, using the following formula:
Vt = 30 sec = wind speed for a 30-second duration
Vt = wind speed over a given duration
ct = conversion factor from Figure 31F-3-1
If wind data is available over land only, the following equation shall be used to convert the wind speed from over-land to over-water conditions [3.5]:
Vw = over water wind speed
VL = over land wind speed
Maximum ebb and flood currents, annual river runoffs and controlled releases shall be considered when establishing the design current velocities for both existing and new MOTs.
Local current velocities may be obtained from NOAA [3.8] or other sources, but must be supplemented by site-specific data, if the current velocity is higher than 1.5 knots.
Site-specific data shall be obtained by real time measurements over a one-year period. If this information is not available, a safety factor of 1.25 shall be applied to the best available data until real time measurements are obtained.
If the facility is not in operation during annual river runoffs and controlled releases, the current loads may be adjusted.
An average current velocity (Vc) shall be used to compute forces and moments. If the current velocity profile is known, the average current velocity can be obtained from the following equation:
Vc = average current velocity (knots)
T = draft of vessel
vc = current velocity as a function of depth (knots)
s = water depth measured from the surface
If the velocity profile is not known, the velocity at a known water depth shall be adjusted by the factors provided in Figure 31F-3-2 to obtain the equivalent average velocity over the draft of the vessel.
The OCIMF MEG3 [3.6] or the UFC 4-159-03 [3.9] procedures shall be used to determine current loads for moored tank vessels.
All MOTs shall consider the predicted SLR over the remaining life of the terminal, due to subsidence or climate change combined with maximum high tide and storm surge. Consideration shall include but not be limited to variation in fender locations, additional berthing loads (deeper draft vessels) and any components near the splash zone.
When the significant wave period, Ts, is greater than 4 seconds (see Section 3105F.3.1), the transverse wave induced vessel reactions shall be calculated using a simplified dynamic mooring analysis described below.
The horizontal water particle accelerations shall be calculated for the various wave conditions, taken at the mid-depth of the loaded vessel draft. The water particle accelerations shall then be used to calculate the wave excitation forces to determine the static displacement of the vessel. The Froude-Krylov method discussed in Chakrabarti's Chapter 7 [3.10] may be used to calculate the wave excitation forces, by conservatively approximating the vessel as a rectangular box with dimensions similar to the actual dimensions of the vessel. The horizontal water particle accelerations shall be calculated for the various wave conditions, taken at the mid-depth of the loaded vessel draft. The computed excitation force assumes a 90-degree incidence angle with the longitudinal axis of the vessel, which will result in forces that are significantly greater than the forces that will actually act upon the vessel from quartering seas. A load reduction factor may be used to account for the design wave incidence angle from the longitudinal axis of the ship. The overall excursion of the vessel shall be determined for each of the wave conditions by calculating the dynamic response of the linear spring mass system.
When required in Section 3105F.3, the sway and surge forces, as well as yaw moment, on a moored vessel, due to passing vessels, shall be established considering the following:
- Ratio of length of moored vessel to length of passing vessel.
- Distance from moored vessel to passing vessel.
- Ratio of midship section areas of the moored and passing vessels.
- Underkeel clearances of the moored and passing vessels.
- Draft and trim of the moored vessel and draft of the passing vessel.
- Mooring line tensions.
The passing vessel's speed should take into consideration the ebb or flood current. Normal operating wind and current conditions can be assumed when calculating forces due to a passing vessel. Either method of Kriebel [3.11] or Wang [3.12] may be used to determine forces on a moored vessel. Kriebel's recent wave tank study improves on an earlier work of Seelig [3.13].
The penetration of long period low amplitude waves into a harbor can result in resonant standing wave systems, when the wave forcing frequency coincides with a natural frequency of the harbor. The resonant standing waves can result in large surge motions if this frequency is close to the natural frequency of the mooring system. Section 3105F.3.3 prescribes the procedure for the evaluation of these effects.
A tsunami may be generated by an earthquake or a subsea or coastal landslide, which may induce large wave heights and excessive currents. The large wave or surge and the excessive currents are potentially damaging, especially if there is a tank vessel moored alongside the MOT wharf.
Tsunamis can be generated either by a distant or near source. A tsunami generated by a distant source (far field event) may allow operators to have an adequate warning for mitigating the risk by allowing the vessels to depart the MOT and go into deep water. For near-field events, with sources less than 500 miles away, the vessel may not have adequate time to depart. Each MOT shall have a "tsunami plan" describing what actions will be performed, in the event of a distant tsunami.
Recent tsunami studies have been completed for both Southern and Northern California. For the Ports of Los Angeles and Long Beach, one of these recent studies focused on near field tsunamis with predicted return periods of 5,000 to 10,000 years [3.14]. These maximum water levels (run-up) would not normally be used for MOT design. However, because the study also provides actual tidal records from recent distant tsunamis, it should be used for design.
The run-up value for Port Hueneme was obtained from an earlier study by Synolakis et al. [3.15].
Run up-values: Port of Los Angeles and Long Beach = 8 ft.
Port Hueneme = 11 ft.
For the San Francisco Bay, a recent study provides the maximum credible tsunami water levels and current speeds. These results are deterministic and are based on the most severe seismic sources that could reasonably impact MOTs in the San Francisco Bay [3.16]. Table 31F-3-6 provides values for the marine oil terminal locations within San Francisco Bay. Water levels could be positive or negative and current velocities may vary in direction. In order to determine the maximum run-up at a MOT, the largest values should be added to the mean high tide. Further details are available in [3.16].
Loads from tsunami-induced waves can be calculated for various structural configurations [3.17]. Tsunami wave heights in shallow water and particle kinematics can also be obtained. Other structural considerations include uplift and debris impact.
Berthing loads are quantified in terms of transfer of kinetic energy of the vessel into potential energy dissipated by the fender(s). The terms and equations below are based on those in UFC 4-152-01 [3.18] and PIANC [3.19].
Kinetic energy shall be calculated from the following equation:
The following correction factors shall be used to modify the actual energy to be absorbed by the fender system for berthing operations:
Efender=Energy to be absorbed by the fender system
FA = Accidental factor accounting for abnormal conditions such as human error, malfunction, adverse environmental conditions or a combination of these factors. For existing berthing systems, FA may be taken as 1.0. For new berthing systems, FA shall be determined in accordance with Section 5-1.5.3 of UFC 4-152-01 [3.18] or PIANC Section 4.2.8 [3.19].
Cb = Berthing Coefficient
Cm = Effective mass or virtual mass coefficient (see Section 3103F.6.6)
The berthing coefficient, Cb, is given by:
Ce = Eccentricity Coefficient
Cc = Configuration Coefficient
Cg = Geometric Coefficient
Cd = Deformation Coefficient
The approximate displacement of the vessel (when only partially loaded) at impact, DT, can be determined from an extension of an equation from Gaythwaite [3.20]:
DWT = Dead Weight Tonnage (in long tons)
dactual = Actual arrival draft of the vessel
dmax = Maximum loaded vessel draft
The berthing load shall be based on the fender reaction due to the kinetic berthing energy. The structural capacity shall be established based on allowable concrete, steel or timber properties in the structural components, as defined in Section 3107F.
For fender system selection, Section 3105F.4.5 shall be followed.
During the berthing maneuver, when the vessel is not parallel to the berthing line (usually the wharf face), not all the kinetic energy of the vessel will be transmitted to the fenders. Due to the reaction from the fender(s), the vessel will start to rotate around the contact point, thus dissipating part of its energy. Treating the vessel as a rigid rod of negligible width in the analysis of the energy impact on the fenders leads to the equation:
k = Longitudinal radius of gyration of the vessel [ft]
a = Distance between the vessel's center of gravity and the point of contact on the vessel's side, projected onto the vessel's longitudinal axis [ft]
The geometric coefficient, Cg, depends upon the geometric configuration of the ship at the point of impact. It varies from 0.85 for an increasing convex curvature to 1.25 for concave curvature. Generally, 0.95 is recommended for the impact point at or beyond the quarter points of the ship, and 1.0 for broadside berthing in which contact is made along the straight side [3.18].
This accounts for the energy reduction effects due to local deformation of the ships hull and deflection of the whole ship along its longitudinal axis. The energy absorbed by the ship depends on the relative stiffness of the ship and the obstruction. The deformation coefficient varies from 0.9 for a nonresilient fender to nearly 1.0 for a flexible fender. For larger ships on energy-absorbing fender systems, little or no deformation of the ship takes place; therefore, a coefficient of 1.0 is recommended.
This factor accounts for the difference between an open pier or wharf and a solid pier or wharf. In the first case, the movements of the water surrounding the berthing vessel is not (or is hardly) affected by the berth. In the second case, the water between the berthing vessel and the structure introduces a cushion effect that represents an extra force on the vessel away from the berth and reduces the energy to be absorbed by the fender system.
For open berth and corners of solid piers, Cc = 1.0
For solid piers with parallel approach, Cc = 0.8
For berths with different conditions, Cc may be interpolated between these values [3.18].
In determining the kinetic energy of a berthing vessel, the effective or the virtual mass is the sum of vessel mass and hydrodynamic mass. The hydrodynamic mass does not necessarily vary with the mass of the vessel, but is closely related to the projected area of the vessel at right angles to the direction of motion.
Other factors, such as the form of vessel, water depth, berthing velocity and acceleration or deceleration of the vessel, will have some effect on the hydrodynamic mass. Taking into account both model and prototype experiments, the effective or virtual mass coefficient can be estimated as:
dactual=Actual arrival draft of the vessel
B = Beam of vessel
The berthing velocity, Vn, is influenced by a large number of factors such as environmental conditions of the site (wind, current and wave), method of berthing (with or without tugboat assistance), condition of the vessel during berthing (ballast or fully laden) and human factors (experience of the tugboat captain).
The berthing velocity, normal to berth, shall be in accordance with Table 31F-3-7. Site condition is determined from Table 31F-3-8.
Subject to Division approval, if an existing MOT can demonstrate lower velocities by utilizing velocity monitoring equipment, then such a velocity may be used temporarily until the berthing system is compliant with this Code.
This section provides methods to determine the wind and current loads acting on the structure directly, as opposed to wind and current forces acting on the structure from a moored vessel.
The current forces acting on the structure may be established using the current velocities, per Section 3103F.5.3.
As a minimum, each component of the structure shall be analyzed for all applicable load combinations given in Table 31F-3-10 or Table 31F-3-11, depending on component type. For additional load combinations, see UFC 4-152-01 [3.18].
The "vacant condition" is the case wherein there is no vessel at the berth. The "mooring and breasting condition" exists after the vessel is securely tied to the wharf. The "berthing condition" occurs as the vessel impacts the wharf, and the "earthquake condition" assumes no vessel is at the berth, and there is no wind or current forces on the structure.
The use of various load types is discussed below:
Upper and lower bound values of dead load are applied for the vacant condition to check the maximum moment and shear with minimum axial load.
Typically, the live load on MOTs is small and may be neglected for combinations including earthquake loads. However, in some cases, a higher value of live load may be warranted depending on MOT use, and an appropriate value of live load shall be considered for combinations including earthquake loads.
Buoyancy forces shall be considered for any submerged or immersed substructures (including pipelines, sumps and structural components).
Mooring line and breasting loads can occur simultaneously or individually, depending on the combination of wind and current. Multiple load cases for operating and survival conditions may be required (see Sections 3103F.5.2 and 3105F.2). In addition, loads caused by passing vessels shall be considered for the "mooring and breasting condition." Refer to Sections 3105F.2 and 3105F.3 for the determination of mooring line and breasting loads.
Berthing is a frequent occurrence, and shall be considered as a normal operating load. No increase in allowable stresses shall be applied for ASD.
Handrails and guardrails shall be designed for 25 plf with a 200-pound minimum concentrated load in any location or direction.
|a||=||Distance between the vessel's center of gravity and the point of contact on the vessel's side, projected onto the vessel's longitudinal axis [ft]|
|A||=||Site Class A as defined in Table 31F-6-1|
|B||=||Beam of vessel|
|B||=||Site Class B as defined in Table 31F-6-1|
|B1||=||Coefficient used to adjust one-second period spectral response, for the effect of viscous damping|
|Bs||=||Coefficient used to adjust the short period spectral response, for the effect of visous damping.|
|C||=||Site Class C as defined in Table 31F-6-1|
|Cm||=||Effective mass or virtual mass coefficient|
|Ct||=||Windspeed conversion factor|
|D||=||Site Class D as defined in Table 31F-6-1|
|DSA||=||Design Spectral Acceleration|
|DSAd||=||DSA values at damping other than 5 percent DT = Displacement of vessel|
|DWT||=||Dead weight tons|
|dactual||=||Arrival maximum draft of vessel at berth|
|dmax||=||Maximum vessel draft (in open seas)|
|E||=||Site Class E as defined in Table 31F-6-1|
|Efender||=||Energy to be absorbed by the fender system|
|Evessel||=||Berthing energy of vessel [ft-lbs]|
|F||=||Site Class F as defined in Table 31F-6-1|
|Fa, Fv||=||Site coefficients from Tables 31F-3-3 and 31F-3-4, respectively|
|FA||=||Accidental factor accounting for abnormal conditions|
|g||=||Acceleration due to gravity [32.2 ft/sec2]|
|h||=||Elevation above water surface [feet]|
|k||=||Radius of longitudinal gyration of the vessel [ft]|
|K||=||Current velocity correction factor (Fig 31F-3-2)|
|PGAX||=||Peak ground acceleration corresponding to the site class under consideration.|
|s||=||Water depth measured from the surface|
|S1||=||Spectral acceleration value (for the boundary of Site Classes B and C) at 1.0 second|
|SS||=||Spectral acceleration value (for the boundary of Site Classes B and C) at 0.2 seconds|
|SX1||=||Spectral acceleration value at 1.0 second corresponding to the period of S1 and the site class under consideration|
|SXS||=||Spectral acceleration value at 0.2 seconds corresponding to the period of SS and the site class under consideration|
|T||=||Draft of vessel (see Figure 31F-3-2)|
|T0||=||Period at which the constant acceleration and constant velocity regions of the design spectrum intersect|
|Vc||=||Average current velocity [knots]|
|vc||=||Current velocity as a function of depth [knots]|
|Vh||=||Wind speed (knots) at elevation h|
|VL||=||Over land wind speed|
|Vn||=||Berthing velocity normal to the berth [ft/sec]|
|vt||=||Velocity over a given time period|
|Vt=30sec||=||Wind speed for a 30 second interval|
|Vw||=||Wind speed at 33-foot (10 m) elevation [knots]|
|W||=||Total weight of vessel and cargo inpounds [displacement tonnage × 2240]|
|WD||=||Water Depth (Figure 31F-3-2)|
[3.1] American Society of Civil Engineers (ASCE), 2017, ASCE/SEI 41-17 (ASCE/SEI 41), "Seismic Evaluation and Retrofit of Existing Buildings," Reston, VA.
[3.2] Federal Emergency Management Agency (FEMA), Nov. 2000, FEMA 356, "Prestandard and Commentary for the Seismic Rehabilitation of Buildings," Washington, D.C.
[3.3] Idriss, I.M. and Sun, J.I., 1992, "User's Manual for SHAKE91, A Computer Program for Conducting Equivalent Linear Seismic Response Analyses of Horizontally Layered Soil Deposits," Center for Geotechnical Modeling, Department of Civil and Environmental Engineering, University of California, Davis, CA.
[3.4] Somerville, Paul G., Smith, Nancy F., Graves, Robert W., and Abrahamson, Norman A., 1997, "Modification of Empirical Strong Ground Motion Attenuation Relations to Include the Amplitude and Duration Effects of Rupture Directivity," Seismological Research Letters, Volume 68, Number 1, pp.199-222.
[3.5] Pile Buck Inc., 1992, "Mooring Systems, A Pile Buck Production," Jupiter, FL.
[3.6] Oil Companies International Marine Forum (OCIMF), 2008, "Mooring Equipment Guidelines (MEG3)," 3rd ed., London, England.
[3.7] Ferritto, J., Dickenson, S., Priestley N., Werner, S., Taylor, C., Burke, D., Seelig, W., and Kelly, S., 1999, "Seismic Criteria for California Marine Oil Terminals," Vol. 1 and Vol. 2, Technical Report TR-2103-SHR, Naval Facilities Engineering Service Center, Port Hueneme, CA.
[3.8] National Oceanic and Atmospheric Administration, Contact: National PORTS Program Manager, Center for Operational Oceanographic Products and Services, 1305 EW Highway, Silver Spring, MD 20910.
[3.9] Department of Defense, 3 October 2005 (Change 2, 23 June 2016), Unified Facilities Criteria (UFC) 4-159-03, "Design: Moorings," Washington, D.C.
[3.10] Chakrabarti, S. K., 1987, "Hydrodynamics of Offshore Structures," Computational Mechanics.
[3.11] Kriebel, David, "Mooring Loads Due to Parallel Passing Ships," Technical Report TR-6056-OCN, US Naval Academy, 30 September 2005.
[3.12] Wang, Shen, August 1975, "Dynamic Effects of Ship Passage on Moored Vessels," Journal of the Waterways, Harbors and Coastal Engineering Division, Proceedings of the American Society of Civil Engineers, Vol. 101, WW3, Reston, VA.
[3.13] Seelig, William N., 20 November 2001, "Passing Ship Effects on Moored Ships," Technical Report TR-6027-OCN, Naval Facilities Engineering Service Center, Washington, D.C.
[3.14] Moffatt & Nichol, April 2007, "Tsunami Hazard Assessment for the Ports of Long Beach and Los Angeles — FINAL REPORT," prepared for the Ports of Long Beach and Los Angeles.
[3.15] Synolakis, C., "Tsunami and Seiche," Chapter 9 in Earthquake Engineering Handbook, Chen, W., Scawthorn, C. S. and Arros, J. K., editors, 2002, CRC Press, Boca Raton, FL.
[3.16] Borrero, Jose, Dengler, Lori, Uslu, Burak and Synolakis, Costas, June 2006, "Numerical Modeling of Tsunami Effects at Marine Oil Terminals in San Francisco Bay," Report for the Marine Facilities Division of the California State Lands Commission.
[3.17] Camfield, Frederick E., February 1980, "Tsunami Engineering," U.S. Army, Corps of Engineers, Coastal Research Center, Special Report No. 6.
[3.18] Department of Defense, 24 January 2017, Unified Facilities Criteria (UFC) 4-152-01, "Design: Piers and Wharves," Washington, D.C
[3.19] Permanent International Association of Navigation Congresses (PIANC), 2002, "Guidelines for the Design of Fender Systems: 2002," Brussels.
[3.20] Gaythwaite, John, 2004, "Design of Marine Facilities for the Berthing, Mooring and Repair of Vessels," American Society of Civil Engineers, Reston, VA.
[3.21] American Society of Civil Engineers (ASCE), 2016, ASCE/SEI 7-16 (ASCE/SEI 7), "Minimum Design Loads and Associated Criteria for Buildings and Other Structures," Reston, VA.
[3.22] Simiu, E. and Scanlan, R., 1978, "Wind Effects on Structures: An Introduction to Wind Engineering," Wiley-Interscience Publications, New York.
Authority: Sections 8750 through 8760, Public Resources Code.
Reference: Sections 8750, 8751, 8755 and 8757, Public Resources Code.
SEISMIC PERFORMANCE CRITERIA1, 2
|SPILL CLASSIFICATION3||SEISMIC PERFORMANCE LEVEL||PROBABILITY OF EXCEEDANCE||RETURN PERIOD|
|High||Level 1||50% in 50 years||72 years|
|Level 2||10% in 50 years||475 years|
|Medium||Level 1||65% in 50 years||48 years|
|Level 2||15% in 50 years||308 years|
|Low||Level 1||75% in 50 years||36 years|
|Level 2||20% in 50 years||224 years|
MINIMUM REQUIRED ANALYTICAL PROCEDURES
|SPILL CLASSIFICATION1||CONFIGURATION||SUBSTRUCTURE MATERIAL||DISPLACEMENT |
|High/Medium||Irregular||Concrete/Steel||Linear Modal||Nonlinear Static|
|High/Medium||Regular||Concrete/Steel||Nonlinear Static2||Nonlinear Static|
|Low||Regular/Irregular||Concrete/Steel||Nonlinear Static||Nonlinear Static|
|High/Medium/Low||Regular/Irregular||Timber||Nonlinear Static||Nonlinear Static|
AMPLIFICATION FACTORS FOR NONSTRUCTURAL COMPONENTS AND NONBUILDING STRUCTURES
|COMPONENT OR STRUCTURE||ap 1, 2|
|Rigid components or structures (period less than 0.06 seconds)||1.0|
|Rigidly attached components or structures||1.0|
|Flexible components or structures (period longer than 0.06 seconds)||2.5|
|Flexibly attached components or structures||2.5|
- A lower value shall not be used unless justified by detailed dynamic analysis, and shall in no case be less than 1.0.
- If the fundamental period of the MOT structure, T, and the period of the flexible nonstructural component or nonbuilding structure, Tp, is known, ap may be estimated from Figure 31F-4-9.
IMPORTANCE FACTORS FOR NONSTRUCTURAL COMPONENTS AND NONBUILDING STRUCTURES
|COMPONENT OR STRUCTURE||lp|
- See Section 3104F.5.1 for definition of critical system.
- A lower value may be utilized, subject to Division approval.
RESPONSE MODIFICATION FACTORS FOR NONSTRUCTURAL COMPONENTS AND NONBUILDING STRUCTURES
|COMPONENT OR STRUCTURE||Rp1|
|Pining/pipelines (threaded or flanged)||6.0|
|Tanks and totes||2.5|
|Light fixtures (or luminaries)||1.5|
|Electrical conduits and cable trays||6.0|
|Velocity monitoring equipment||2.5|
|Instrumentation or storage cabinets||6.0|
|Gangway (column systems)||3.0|
|Gangways (truss systems)||Use Rp from frame systems|
|Hose towers and racks||Use Rp from frame systems|
|Frame systems: |
Steel special concentrically braced framesSteel ordinary concentrically braced frames
Steel special moment framesSteel intermediate moment frames
Steel ordinary moment frames
Lightframe wood sheathed with wood structural panels
Lightframe cold-formed steel sheathed with wood structural panelsLightframe walls with shear panels of other materials
|Other||Subject to Division approval|
- A higher value may be utilized, subject to Division approval.
The purpose of this section is to establish minimum standards for seismic analysis and structural performance. Seismic performance is evaluated at two criteria levels. Level 1 requirements define a performance criterion to ensure MOT functionality. Level 2 requirements safeguard against major damage, collapse or major oil spill.
Section 3104F applies to all new and existing MOTs. Structures supporting loading arms, pipelines, oil transfer and storage equipment, critical systems and vessel mooring structures, such as mooring and breasting dolphins are included. Catwalks and similar components that are not part of the lateral load carrying system and do not support oil transfer equipment may be excluded.
Each MOT structure shall be designated as regular or irregular based on torsional irregularity criteria presented in ASCE/SEI 7 [4.1]. An MOT structure is defined to be irregular when maximum displacement at one end of the MOT structure transverse to an axis is more than 1.2 times the average of the displacement at the two ends of the MOT structure, as described in Figure 31F-4-1. For MOTs with multiple segments separated by expansion joints, each segment shall be designated as regular or irregular using criteria in this section. Expansion joints in this context are defined as joints that separate each structural segment in such a manner that each segment will move independently during an earthquake.
Two levels of seismic performance shall be considered, except for critical systems (Section 3104F.5.1). These levels are defined as follows:
Level 1 Seismic Performance:
• Minor or no structural damage
• Temporary or no interruption in operations
Level 2 Seismic Performance:
• Controlled inelastic behavior with repairable damage
• Prevention of collapse
• Temporary loss of operations, restorable within months
• Prevention of major spill (≥ 1200 bbls)
The Level 1 and Level 2 seismic performance criteria are defined in Table 31F-4-1.
Component capacities shall be based on existing conditions, calculated as "best estimates," taking into account the mean material strengths, strain hardening and degradation overtime. The capacity of components with little or no ductility, which may lead to brittle failure scenarios, shall be calculated based on lower bound material strengths. Methods to establish component strength and deformation capacities for typical structural materials and components are provided in Section 3107F. Geotechnical considerations are discussed in Section 3106F.
The objective of the seismic analysis is to verify that the displacement capacity of the structure is greater than the displacement demand, for each performance level defined in Table 31F-4-1. For this purpose, the displacement capacity of each element of the structure shall be checked against its displacement demand including the orthogonal effects of Section 3104F.4.2. The required analytical procedures are summarized in Table 31F-4-2.
The displacement capacity of the structure shall be calculated using the nonlinear static (pushover) procedure. For the nonlinear static (pushover) procedure, the pushover load shall be applied at the target node defined as the center of mass (CM) of the MOT structure. It is also acceptable to use a nonlinear dynamic procedure for capacity evaluation, subject to peer review in accordance with Section 3101F.8.2.
Methods used to calculate the displacement demand are linear modal, nonlinear static and nonlinear dynamic.
Mass to be included in the displacement demand calculation shall include mass from self-weight of the structure, weight of the permanent equipment, and portion of the live load that may contribute to inertial mass during earthquake loading, such as a minimum of 25% of the floor live load in areas used for storage.
Any rational method, subject to the Division's approval, can be used in lieu of the required analytical procedures shown in Table 31F-4-2.
To assess displacement capacity, two-dimensional nonlinear static (pushover) analyses shall be performed; three-dimensional analyses are optional. A model that incorporates the nonlinear load deformation characteristics of all components for the lateral force-resisting system shall be used in the pushover analysis.
Alternatively, displacement capacity of a pile in the MOT structure may be estimated from pushover analysis of an individual pile with appropriate axial load and pile-to-deck connection.
The displacement capacity of a pile from the pushover analysis shall be defined as the displacement that can occur at the top of the pile without exceeding plastic rotation (or material strain) limits, either at the pile-deck hinge or in-ground hinge, as defined in Section 3107F. If pile displacement has components along two axes, as may be the case for irregular MOTs, the pile displacement capacity shall be defined as the resultant of its displacement components along the two axes.
A series of nonlinear pushover analyses may be required depending on the complexity of the MOT structure. At a minimum, pushover analysis of a two-dimensional model shall be conducted in both the longitudinal and transverse directions. The piles shall be represented by nonlinear elements that capture the moment-curvature/rotation relationships for components with expected inelastic behavior in accordance with Section 3107F. The effects of connection flexibility shall be considered in pile-to-deck connection modeling. For prestressed concrete piles, Figure 31F-4-2 may be used. A nonlinear element is not required to represent each pile location. Piles with similar lateral force-deflection behavior may be lumped in fewer larger springs, provided that the overall torsional effects are captured.
For all timber pile supported structures, linear elastic procedures may be used. Alternatively, the nonlinear static procedure may be used to estimate the target displacement demand, Δd.
A simplified single pile model for a typical timber pile supported structure is shown in Figure 31F-4-3. The pile-deck connections may be assumed to be "pinned." The lateral bracing can often be ignored if it is in poor condition. These assumptions shall be used for the analysis, unless a detailed condition assessment and lateral analysis indicate that the existing bracing and connections may provide reliable lateral resistance.
A series of single pile analyses may be sufficient to establish the nonlinear springs required for the pushover analysis.
A nonlinear static procedure shall be used to determine the displacement demand for all concrete and steel structures, with the exception of irregular configurations with high or moderate spill classifications. A linear modal procedure is required for irregular structures with high or moderate spill classifications, and may be used for all other classifications in lieu of the nonlinear static procedure.
In the nonlinear static demand procedure, deformation demand in each element shall be computed at the target node displacement demand. The analysis shall be conducted in each of the two orthogonal directions and results combined as described in Section 3104F.4.2.
The target displacement demand of the structure, Δd, shall be calculated from:
Te = effective elastic structural period defined in Equation (4-3) or Equation (4-9)
SA = spectral response acceleration corresponding to Te
If Te < T0, where T0 is the period corresponding to the peak of the acceleration response spectrum, a refined analysis (see Section 3104F.220.127.116.11 or 3104F.18.104.22.168) shall be used to calculate the displacement demand. In the refined analysis, the target node displacement demand may be computed from the Coefficient Method (Section 3104F.22.214.171.124) or the Substitute Structure Method (Section 3104F.126.96.36.199). Both of these methods utilize the pushover curve developed in Section 3104F.2.3.1.
The Coefficient Method is based on the procedures presented in ASCE/SEI 41 [4.3] and FEMA 440 [4.4].
The first step in the Coefficient Method requires idealization of the pushover curve to calculate the effective elastic lateral stiffness, ke, and effective yield strength, Fy, of the structure as shown in Figure 31F-4-4.
The first line segment of the idealized pushover curve shall begin at the origin and have a slope equal to the effective elastic lateral stiffness, ke. The effective elastic lateral stiffness, ke, shall be taken as the secant stiffness calculated at the lateral force equal to 60 percent of the effective yield strength, Fy, of the structure. The effective yield strength, Fy, shall not be taken as greater than the maximum lateral force at any point along the pushover curve.
The second line segment shall represent the positive post-yield slope (α1ke) determined by a point (Fd,Δd) and a point at the intersection with the first line segment such that the area above and below the actual curve area approximately balanced. (Fd,Δd) shall be a point on the actual pushover curve at the calculated target displacement, or at the displacement corresponding to the maximum lateral force, whichever is smaller.
The third line segment shall represent the negative post-yield slope (α2ke), determined by the point at the end of the positive post-yield slope (Fd,Δd) and the point at which the lateral force degrades to 60 percent of the effective yield strength.
The target displacement shall be calculated from:
SA = spectral acceleration of the linear-elastic system at vibration period, which is computed from:
ke = effective elastic lateral stiffness from idealized pushover
C1 = modification factor to relate maximum inelastic displacement to displacement calculated for linear elastic response. For period less than 0.2 s, C1 need not be taken greater than the value at Te = 0.2 s. For period greater than 1.0 s, C1 = 1.0. For all other periods:
a = Site class factor
= 130 for Site Class A or B,
= 90 for Site Class C, and
= 60 for Site Class D, E or F.
µstrength = ratio of elastic strength demand to yield strength coefficient calculated in accordance with Equation (4-6). The Coefficient Method is not applicable where µstrength exceeds µmax computed from Equation (4-7). µstrength shall not be taken as less than 1.0.
C2 = modification factor to represent the effects of pinched hysteresis shape, cyclic stiffness degradation and strength deterioration on the maximum displacement response. For periods greater than 0.7s, C2 = 1.0. For all other periods:
Δd = larger of target displacement or displacement corresponding to the maximum pushover force,
Δy = displacement at effective yield strength
αe = effective negative post-yield slope ratio which shall be computed from:
αP-Δ, and the maximum negative post-elastic stiffness ratio, α2, are estimated from the idealized force-deformation curve, and λ is a near-field effect factor equal to 0.8 for sites with 1 second spectral value, S1 greater than or equal to 0.6g and equal to 0.2 for sites with 1 second spectral value, S1 less than 0.6g.
The Substitute Structure Method is based on the procedure presented in Priestley et al. [4.5] and ASCE/COPRI 61 [4.2]. This method is summarized below.
- Idealize the pushover curve from nonlinear pushover analysis, as described in Section 3104F.188.8.131.52, and estimate the effective yield strength, Fy, and yield displacement, Δy.
- Compute the effective elastic lateral stiffness, ke, as the effective yield strength, Fy, divided by the yield displacement, Δy.
- Compute the structural period in the direction under consideration from:
- Determine target displacement, Δd , of the effective linear elastic system from:(4-11)SA = the 5 percent damped spectral displacement corresponding to the linear elastic structural period, TeSelect the initial estimate of the displacement demand as Δd, i = Δd.
- The ductility level, µΔ,i , is found from Δd,i /Δy. Use the appropriate relationship between ductility and damping, for the component undergoing inelastic deformation, to estimate the effective structural damping, ξeff,i. In lieu of more detailed analysis, Equation (4-12) may be used for concrete and steel piles connected to the deck through dowels embedded in the concrete. Note that the idealized pushover curves in Figure 31F-4-4 shall be utilized in Figure 31F-4-5, which illustrates the iterative procedure.Equation (4-12) for effective damping was developed by Kowalsky et al. [4.6] for the Takeda hysteresis model of system's force-displacement relationship.
- Compute the force, Fd,i, on the force-deformation relationship associated with the estimated displacement, Δd,i (see Figure 31F-4-5).
- Compute the effective stiffness, keff,i, as the secant stiffness from:(4-13)
- Compute the effective period, Teff,i, from:
- For the effective structural period, Teff,i, and the effective structural damping, ξeff,i, compute the spectral acceleration SA(Teff,i, ξeff,i) from an appropriately damped design acceleration response spectrum.
- Compute the new estimate of the displacement, Δd, j, from:(4-15)
- Repeat steps 5 to 10 with Δd, i = Δd, j until displacement, Δd, j, computed in step 10 is sufficiently close to the starting displacement, Δd, i, in step 5 (Figure 31F-4-5).
For irregular concrete/steel structures with moderate or high spill classifications, a linear modal analysis is required to predict the global displacement demands. A 3-D linear elastic response analysis shall be used, with effective moment of inertia applied to components to establish lateral displacement demands, to compute displacement components of an element along each axis of the system.
Sufficient modes shall be included in the analysis such that 90 percent of the participating mass is captured in each of the principal horizontal directions for the structure. For modal combinations, the Complete Quadratic Combination rule shall be used. Multidirectional excitation shall be accounted for in accordance with Section 3104F.4.2.
The lateral stiffness of the linear elastic response model shall be based on the initial stiffness of the non-linear pushover curve as shown in Figure 31F-4-6 (also see Section 3106F.9). The p-y springs shall be adjusted based on the secant method approach. Most of the p-y springs will typically be based on their initial stiffness; no iteration is required.
If the fundamental period is T < T0, where T0 is the period corresponding to the peak of the acceleration response spectrum, the displacement demand from the linear modal analysis shall be amplified to account for nonlinear system behavior by an amplification factor. The amplification factor shall be equal to either C1 × C2 per Section 3104F.184.108.40.206, or the ratio of the final target displacement and the initial elastic displacement of Equation (4-11) per Section 3104F.220.127.116.11.
Nonlinear dynamic time history analysis is optional, and if performed, a peer review is required (see Section 3101F.8.2). Multiple acceleration records shall be used, as explained in Section 3103F.4.2.10. The following assumptions may be made:
- Equivalent "super piles" can represent groups of piles.
- If the deck has sufficient rigidity (both in-plane and out-of-plane) to justify its approximation as a rigid element, a 2-D plan simulation may be adequate.
A time-history analysis should always be compared with a simplified approach to ensure that results are reasonable. Displacements calculated from the nonlinear time history analyses may be used directly in design, but shall not be less than 80 percent of the values obtained from Section 3104F.2.3.2.
The analysis and design requirements described in Section 3104F.2 shall also apply to new MOTs. However, new MOTs shall comply with the seismic performance criteria for high spill classification, as defined in Table 31F-4-1. Additional requirements are as follows:
The P-Δ effect (i.e., the additional moment induced by the total vertical load multiplied by the lateral deck deflection) shall be considered unless the following relationship is satisfied (see Figure 31F-4-8):
For wharf structures where the lateral displacement is limited by almost fully embedded piles, P-Δ effects may be ignored; however, the individual stability of the piles shall be checked in accordance with Section 3107F.2.5.2.
If the landside batter piles are allowed to fail in a Level 2 evaluation, the remaining portion of the wharf shall be checked for P-Δ effects.
The effect of expansion joints shall be considered in the seismic analysis.
Shear force across shear keys connecting adjacent wharf segments, Vsk, (approximate upper bound to the shear key force [4.7]) shall be calculated as follows:
VΔT = total segment lateral force found from a pushover analysis
Ll = segment length
e = eccentricity between the center of rigidity and the center of mass
For an existing wharf, the deteriorated conditions at the junction between the pile top and pile cap shall be considered in evaluating the moment capacity. Connection detail between the vertical pile and pile cap shall be evaluated to determine whether full or partial moment capacity can be developed under seismic action.
For new MOTs, the connection details shall develop the full moment capacities.
Batter piles primarily respond to earthquakes by developing large axial compression or tension forces. Bending moments are generally of secondary importance. Failure in compression may be dictated by the deck-pile connection (most common type), material compression, buckling or by excessive local shear in deck members adjacent to the batter pile. Failure in tension may be dictated by connection strength or by pile pull out (p. 3-83 of Ferritto et al. [4.7]).
When the controlling failure scenario is reached and the batter pile fails, the computer model shall be adjusted to consist of only the vertical pile acting either as a full or partial moment frame based on the connection details between the pile top and pile cap. The remaining displacement capacity, involving vertical piles, before the secondary failure stage develops, shall then be established (see Section 3107F.2.8).
Axial p-z curves shall be modeled. In compression, displacement capacity should consider the effect of the reduction in pile modulus of elasticity at high loads and the increase in effective length for friction piles. This procedure allows the pile to deform axially before reaching ultimate loads, thereby increasing the displacement ductility [4.7].
Horizontal nonlinear p-y springs are only applied to batter piles with significant embedment, such as for landside batter piles in a wharf structure. Moment fixity can be assumed for batter piles that extend well above the ground such as waterside batter piles in a wharf structure or batter piles in a pier type structure.
Nonstructural components, nonbuilding structures and building structures at MOTs shall be assessed for Level 2 seismic performance (see Section 3104F.2.1). Consideration shall be given to the adequacy and condition of supports and attachments (or anchorage), strength, flexibility, relative displacement, P-delta effects, and seismically-induced interaction with other components and structures.
Nonstructural components are mechanical, electrical and architectural components (such as piping/pipelines, loading arms, lifting equipment (winches and cranes), spill prevention equipment, pumps, instrumentation and storage cabinets, and lighting fixtures) that may be required to resist the effects of earthquake.
Nonbuilding structures (such as gangways, hose towers and racks) are self-supporting structures that carry gravity loads and may be required to resist the effects of earthquake, but are not building structures (such as control rooms). For building structures, see Section 3104F.5.6.
Critical systems are nonstructural components, nonbuilding structures or building structures that shall remain operational or those whose failure could impair emergency operations following an earthquake, to prevent major oil spills and to protect public health, safety and the environment. A seismic assessment of the survivability and continued operation (related to personnel safety, oil spill prevention or response) during a Level 2 earthquake (see Table 31F-4-1) shall be performed for critical systems, including but not limited to, fire protection, emergency shutdown and electrical power systems.
For existing (E) nonstructural components, nonbuilding structures and building structures and their supports and attachments, seismic assessment shall be performed in accordance with CalARP [4.8] or ASCE Guidelines [4.9], except for piping/pipelines which shall be evaluated per Section 3109F. If seismic evaluation and/or strengthening are required, it shall be performed in accordance with Section 3104F.5.2.1.
For evaluation, strengthening and design of nonstructural components, nonbuilding structures and building structures, seismic forces (demands) shall be obtained from Section 3104F.5. The seismic adequacy of nonstructural components shall be demonstrated as specified in ASCE/SEI 7 [4.1]. Structures shall be analyzed in accordance with Section 3107F.5. Supports and attachments shall be assessed in accordance with Sections 3107F.7.
Nonstructural components, nonbuilding structures and building structures permanently attached to MOT structures, including, but not limited to, pipelines, loading arms, hose towers/racks, raised platforms, control rooms and vapor control equipment, may affect the global structural response. In such cases, the seismic characteristics (mass and/or stiffness) of the nonstructural components, nonbuilding structures and building structures shall be considered in computing global seismic response of the MOT structures. If the seismic response of nonstructural components is determined to be out of phase (e.g. pipelines) with the global structural response, then the mass contribution can be neglected in the seismic structural analysis.
3104F.5.4 Nonstructural Components and Nonbuilding Structures Permanently Attached to MOT Structures
This section covers nonstructural components and nonbuilding structures having a significant mass and/or importance to the operability and safety of the MOT, and that are permanently attached to MOT structures (e.g., wharves, trestles, dolphins). The weight of nonstructural components and nonbuilding structures shall be included in the dead load of the structure per Section 3103F.2.
Computation of seismic effects shall consider:
- Amplification of acceleration from ground to location of attachment of the nonstructural component or nonbuilding structure to the deck due to flexibility of the MOT structure, and
- Amplification of acceleration due to flexibility of the nonstructural component or nonbuilding structure.
The following are not covered in this section and shall be assessed using rational approach that includes consideration of strength, stiffness, ductility and seismic interaction with all other connected components and with the supporting structures or systems, subject to Division approval:
- Nonstructural component supported by other nonstructural system permanently attached to MOT structure;
- Nonstructural component or nonbuilding structure supported by other structure permanently attached to MOT structure;
- Nonstructural component or nonbuilding structure attached to multiple MOT structures;
- Nonstructural component or nonbuilding structure attached to structure and ground.
This section specifies the procedure to compute seismic loads on nonstructural components and nonbuilding structures permanently attached to a MOT structure.
The following nonstructural components are exempt from the requirements of this section:
- Temporary or movable equipment unless part of a critical system (Section 3104F.5.1);
- Mechanical and electrical components that are attached to the MOT structure and have flexible connections to associated piping and conduit; and either:
- The component weighs 400 lb or less, the center of mass is located 4 ft or less above the MOT deck, and the component Importance Factor, I p is equal to 1.0; or
- The component weighs 20 lb or less, or in the case of a distributed system, 5 lb/ft or less.
The Simplified Procedure may be used to estimate seismic loads on nonstructural components and nonbuilding structures permanently attached to a MOT structure. The Simplified Procedure shall not be used if any of the following apply:
- Mass of the nonstructural component or nonbuilding structure exceeds 25 percent of the combined mass of the MOT structure plus nonstructural component or nonbuilding structure;
- Multiple nonstructural components or nonbuilding structures of similar type (or natural period) when their combined mass exceeds 25 percent of the total mass of the MOT structure plus nonstructural components or nonbuilding structures;
- Concrete/Steel MOT structure with irregular configuration (Section 3104F.1.3 and Table 31F-4-2) and high or medium spill exposure classification.
The horizontal seismic force, Fp , shall be computed as follows [4.10]:
ap = amplification factor for nonstructural component or nonbuilding structure (Table 31F-4-3)
Ip = importance factor for nonstructural component or nonbuilding structure (Table 31F-4-4)
Wp = weight of the nonstructural component or nonbuilding structure
Rp = response modification factor for nonstructural component or nonbuilding structure (Table 31F-4-5)
Alternatively, when dynamic properties of the MOT structure are available, the horizontal seismic force, Fp, may be computed from [4.10]:
Δm = maximum displacement at one end of the MOT structure transverse to an axis
Δavg = average of the displacements at the extreme points of the MOT structure (see Figure 31F-4-1)
The horizontal seismic force, Fp, in the direction under consideration shall be applied at the center of gravity and distributed relative to the mass distribution of the nonstructural component or nonbuilding structure.
The horizontal seismic force, Fp, shall be applied independently in at least two orthogonal horizontal directions in combination with service or operating loads associated with the nonstructural component or nonbuilding structure, as appropriate. For vertically cantilevered systems, however, Fp shall be assumed to act in any horizontal direction.
The concurrent vertical seismic force, Fv, shall be applied at the center of gravity and distributed relative to the mass distribution of the nonstructural component or nonbuilding structure, as follows:
The linear modal demand procedure (Section 3104F.2.3.3) may always be used and shall be used to estimate seismic forces when the Simplified Procedure (Section 3104F.18.104.22.168) is not permitted. The MOT structure and nonstructural components and/or nonbuilding structures shall be modeled explicitly. The seismic forces obtained from the linear modal demand procedure shall be adjusted for appropriate importance factors and response modification factors as specified in Table 31F-4-4 and Table 31F-4-5.
The seismic load shall be computed using the procedures in ASCE/SEI 7 [4.1], except that Level 2 design earthquake motion parameters defined in Section 3103F.4 shall be used in lieu of those specified in ASCE/SEI 7 [4.1].
For buildings permanently attached to MOT structure, Section 3104F.5.4.1 shall be used to compute seismic loads. Computation of seismic effects shall consider:
- Amplification of acceleration from ground to location of attachment of the building to the deck due to flexibility of the MOT structure, and
- Amplification of acceleration due to flexibility of the building.
|a||=||Site class factor|
|ap||=||Amplification factor for nonstructural component or nonbuilding structure|
|Ax||=||Torsional amplification factor|
|C1||=||Modification factor to relate expected maximum inelastic displacement to displacement calculated for linear elastic response|
|C2||=||Modification factor to represent the effects of pinched hysteresis shape, cyclic stiffness degradation and strength deterioration on the maximum displacement response|
|e||=||Eccentricity between center of mass and center of rigidity|
|Fd, i||=||Force at step i of iteration|
|Fd, j||=||Force at step j of iteration|
|Fp||=||Horizontal seismic force on nonstructural component, nonbuilding structure or building structure supported on MOT|
|Fv||=||Vertical seismic force on nonstructural component, nonbuilding structure or building structure supported on MOT|
|Fy||=||Effective yield strength|
|H||=||Distance from maximum in-ground moment to center of gravity of the deck|
|Ip||=||Importance factor for nonstructural component or nonbuilding structure|
|ke||=||Effective elastic lateral stiffness|
|keff, i||=||Effective secant lateral stiffness at step i of iteration|
|keff, j||=||Effective secant lateral stiffness at step j of iteration|
|Ll||=||Longitudinal length between wharf expansion joints|
|Rp||=||Response modification factor for nonstructural component or nonbuilding structure|
|SA||=||Spectral response acceleration at T|
|Sxs||=||Spectral acceleration in Section 3103F.4.2.4 or Section 3103F.4.2.5|
|S1||=||1-second spectral response acceleration|
|T||=||Fundamental period of the elastic structure|
|Te||=||Effective elastic structural period|
|Teff, i||=||Effective structural period at step i of iteration|
|Tp||=||Period of flexible nonstructural component or nonbuilding structure|
|T0||=||Period at peak of the acceleration response spectrum|
|V||=||Base shear strength of the structure obtained from a plastic analysis|
|Vsk||=||Shear force across shear keys|
|VΔT||=||Total segment lateral force|
|W||=||Dead load of the frame|
|Wp||=||Weight of the nonstructural component or nonbuilding structure|
|Δd||=||Target displacement demand|
|Δd, i||=||Target displacement demand at step i of iteration|
|Δd, j||=||Target displacement demand at step j of iteration|
|α1||=||Positive post-yield slope ratio equal to positive post-yield stiffness divided by the effective stiffness|
|α2||=||Negative post-yield slope ratio equal to negative post-yield stiffness divided by the effective stiffness|
|αe||=||Effective negative post-yield slope ratio equal to effective post-yield negative stiffness divided by the effective stiffness|
|αP-Δ||=||Negative slope ratio caused by P-Δ effects|
|Δavg||=||Average of displacements, Δ1 and Δ2, at ends of the MOT transverse to an axis|
|Δm||=||Maximum of displacements, Δ1 and Δ2, at ends of the MOT transverse to an axis|
|Δy||=||Displacement at yield strength|
|Δ1, Δ2||=||Displacement at ends of the MOT transverse to an axis|
|δd||=||Design displacement demand at an element|
|δx||=||Displacement of an element in X direction|
|δy||=||Displacement of an element in Y direction|
|δxx||=||X displacement under X direction excitation|
|δxy||=||X displacement under Y direction excitation|
|δyx||=||Y displacement under X direction excitation|
|δyy||=||Y displacement under Y direction excitation|
|λ||=||Near-field effect factor|
|µmax||=||Maximum strength ratio|
|µstrength||=||Ratio of elastic strength demand to yield strength|
|µΔ,ι||=||Initial ductility level|
|ξeff,i||=||Effective structural damping at step i of iteration|
[4.1] American Society of Civil Engineers (ASCE), 2016, ASCE/SEI 7-16 (ASCE/SEI 7), "Minimum Design Loads and Associates Criteria for Buildings and Other Structures," Reston, VA.
[4.2] American Society of Civil Engineers (ASCE), 2014, ASCE/COPRI 61-14 (ASCE/COPRI 61), "Seismic Design of Piers and Wharves," Reston, VA.
[4.3] American Society of Civil Engineers (ASCE), 2017, ASCE/SEI 41-17 (ASCE/SEI 41), "Seismic Evaluation and Retrofit of Existing Buildings," Reston, VA.
[4.4] Federal Emergency Management Agency (FEMA), June 2005, FEMA 440, "Improvement of Nonlinear Static Seismic Analysis Procedures," Redwood City, CA.
[4.5] Priestley, M.J.N., Seible, F., Calvi, G.M., 1996, "Seismic Design and Retrofit of Bridges," John Wiley & Sons, Inc., New York.
[4.6] Kowalsky, M.J., Priestley, M.J.N, MacRae, G.A., 1994, "Displacement-Based Design — A Methodology for Seismic Design Applied to Single Degree of Freedom Reinforced Concrete Structures," Report No. SSRP — 94/16, University of California, San Diego.
[4.7] Ferritto, J., Dickenson, S., Priestley N., Werner, S., Taylor, C., Burke, D., Seelig, W., and Kelly, S., 1999, "Seismic Criteria for California Marine Oil Terminals," Vol. 1 and Vol. 2, Technical Report TR-2103-SHR, Naval Facilities Engineering Service Center, Port Hueneme, CA.
[4.8] CalARP Program Seismic Guidance Committee, December 2013, "Guidance for California Accidental Release Prevention (CalARP) Program Seismic Assessments," Sacramento, CA.
[4.9] American Society of Civil Engineers, 2011, "Guidelines for Seismic Evaluation and Design of Petrochemical Facilities," 2nd ed., New York.
[4.10] Goel, R. K., 2017, "Estimating Seismic Forces in Ancillary Components and Nonbuilding Structures Supported on Piers, Wharves, and Marine Oil Terminals," Earthquake Spectra, https://doi.org/10.1193/041017EQS068M.
Authority: Sections 8750 through 8760, Public Resources Code.
Reference: Sections 8750, 8751, 8755 and 8757, Public Resources Code.
|VESSEL SIZE (DWT)||CONTACT LENGTH|
|1,000 to 2,500||35 ft|
|5,000 to 26,000||40 ft|
|35,000 to 50,000||50 ft|
|100,000 to 125,000||70 ft|
COEFFICIENT OF FRICTION
|CONTACT MATERIALS||FRICTION COEFFICIENT|
|Timber to Steel||0.4 to 0.6|
|Urethane to Steel||0.4 to 0.6|
|Steel to Steel||0.25|
|Rubber to Steel||0.6 to 0.7|
|UHMW* to Steel||0.1 to 0.2|
*Ultra-high molecular weight plastic rubbing strips.
SAFETY FACTORS FOR ROPES [5.4]
|Steel Wire Rope||1.82|
|Polyamide Tail for Wire Mooring Lines||2.50|
|Other Synthetic Tail for Wire Mooring Lines||2.28|
|Polyamide Tail for Synthetic Mooring Lines||2.75|
|Other Synthetic Tail for Synthetic Mooring Lines||2.50|
ALLOWABLE WORKING LOADS
|TYPE OF FITTINGS||NO. OF BOLTS||BOLT SIZE
|30 inch Cleat||4||11/8||20|
|42 inch Cleat||6||11/8||40|
|Low Bitt||10||15/8||60 per column|
|High Bitt||10||13/4||75 per column|
|441/2 inch Fit. Bollard||4||13/4||70|
|441/2 inch Fit. Bollard||8||21/4||200|
|48 inch Fit. Bollard||12||23/4||450|
This section establishes minimum standards for safe mooring and berthing of vessels at MOTs.
This section applies to onshore MOTs; Figure 31F-5-1 shows typical pier and wharf configurations.
Multiple berth MOTs shall use the same environmental input conditions for each berth unless it can be demonstrated that there are significant differences.
MOTs shall have the following equipment in operation:
- An anemometer (N/E).
- A current meter in high velocity current (>1.5 knots) areas (N/E).
- Remote reading tension load devices in high velocity current (>1.5 knots) areas and/or with passing vessel effects for new MOTs.
- Mooring hardware in accordance with Section 3105F.8 (N/E).
Berthing systems shall be in accordance with Section 3105F.4 (N/E).
Quick release hooks are required at all new MOTs, except for spring line fittings. Quick release hooks shall be sized in accordance with Section 3105F.8 To avoid accidental release, the freeing mechanism shall be activated by a two-step process. Quick release hooks shall be insulated electrically from the mooring structure, and shall be supported so as not to contact the deck.
Section 3105F.5 and the OCIMF guidelines [5.4] shall be used in designing the mooring layout.
The existing condition of the MOT shall be used in the mooring analysis (see Section 3102F). Structural characteristics of the MOT, including type and configuration of mooring fittings such as bollards, bitts, hooks and capstans and material properties and condition, shall be determined in accordance with Sections 3107F.7 and 3105F.8.
A mooring analysis shall be performed for each berthing system, to justify the safe mooring of the various vessels at the MOT. Review of vessels calling at the MOT shall be performed to identify representative vessel size ranges and mooring configurations. Vessels analyzed shall be representative of the upper bound of each vessel size range defined by DWT capacity (see Section 3101F.6). The Terminal Operating Limits (TOLs) shall be generated based on the mooring analyses (see Section 3102F.3.6.1 and Figure 31F-2-1).
The forces acting on a moored vessel shall be determined in accordance with Section 3103F.5. Mooring line and breasting load combinations shall be in accordance with Section 3103F.8.
Two procedures, manual and numerical, are available for performing mooring analyses. These procedures shall conform to either the OCIMF (MEG 3) [5.4] or UFC 4-159-03 [5.5]. The manual procedure (Section 3105F.2.1) may be used for barges. In order to simplify the analysis for barges (or other small vessels), they may be considered to be solid free-standing walls (Chapter 29 of ASCE/SEI 7 [5.6]). This will eliminate the need to perform a computer assisted mooring analysis.
A new mooring assessment shall be performed when conditions change, such as any modification in the mooring configuration, vessel size or new information indicating greater wind, current or other environmental loads.
The most severe combination of the environmental loads and limiting conditions shall be justified based on site-specific evaluation, and considered in the mooring analyses. At a minimum, the following shall be considered and documented:
- Two current directions (maximum ebb and flood; See Section 3103F.5.3)
- Two tide levels (highest high and lowest low)
- Two vessel loading conditions (ballast and maximum draft at the terminal)
- Eight wind directions (45 degree increments)
- Vessel motion limits (as applicable)
- Fender properties
- Mooring hardware capacities
- Minimum mooring line properties (such as MBL of the weakest line permitted for vessel size range)
- Passing vessel forces
In general, vessels shall remain in contact with the breasting or fendering system. Vessel motion (sway) of up to 2 feet off the breasting structure may be allowed under the most severe environmental loads, unless greater movement can be justified by an appropriate mooring analysis that accounts for potential dynamic effects. The allowable movement shall be consistent with mooring analysis results, indicating that forces in the mooring lines and their supports are within the allowable safety factors. Also, a check shall be made as to whether the movement is within the limitations of the cargo transfer equipment.
The mooring analyses outputs define the wind load and other limitations.
Upon completion of the mooring analyses, the following shall be checked, as applicable:
- The fender system compression/deflection performance.
- Anchorage capacity of each mooring hardware component.
- Capacity of supporting structure(s) exceed each mooring line demand.
- Maximum allowable capacities for mooring lines.
- Vessel motion does not exceed the maximum allowable extension limits of the loading arms and/or hoses.
Simplified calculations may be used to determine the mooring forces for barges with Favorable Site Conditions (see Table 31F-3-8) and no passing vessel effects (see Section 3105F.3.2), except if any of the following conditions exist (Figures 31F-5-2 and 31F-5-3).
- Mooring layout is significantly asymmetrical
- Horizontal mooring line angles (α) on bow and stern exceed 45 degrees
- Horizontal breast mooring line angles exceed 15 normal to the hull
- Horizontal spring mooring line angles exceed 10 degrees from a line parallel to the hull
- Vertical mooring line angles (θ) exceed 25 degrees
- Mooring lines for lateral loads not grouped at bow and stern
When the forces have been determined and the distance between the bow and stern mooring points is known, the yaw moment can be resolved into lateral loads at the bow and stern. The total environmental loads on a moored vessel are comprised of the lateral load at the vessel bow, the lateral load at the vessel stern and the longitudinal load. Line pretension loads must be added.
Four load cases shall be considered:
- Entire load is taken by mooring lines
- Entire load is taken by breasting structures
- Load is taken by combination of mooring lines and breasting structures
- Longitudinal load is taken only by spring lines
A numerical procedure is required to obtain mooring forces for MOTs that cannot use manual procedure. Computer program(s) shall be based on mooring analysis procedures that consider the characteristics of the mooring system, calculate the environmental loads and provide resulting mooring line forces and vessel motions (surge and sway).
MOTs are generally located in sheltered waters such that typical wind waves can be assumed not to affect the moored vessel if the significant wave period, Ts, is less than 4 seconds. However, if the period is equal to or greater than 4 seconds, then a simplified dynamic analysis (See Section 3103F.5.4) is required. The wave period shall be established based on a 1-year significant wave height, Hs. For MOTs within a harbor basin, the wave period shall be based on the locally generated waves with relatively short fetch.
These forces generated by passing vessels are due to pressure gradients associated with the flow pattern. These pressure gradients cause the moored vessel to sway, surge and yaw, thus imposing forces on the mooring lines.
Passing vessel analysis shall be conducted when all of the following conditions exist (See Figure 31F-5-4):
- Passing vessel size is greater than 25,000 DWT.
- Distance L is 500 feet or less
- Vessel speed V is greater than Vcrit
Exception: If L ≤ 2B, passing vessel loads shall be considered.
L and B are shown in Figure 31F-5-4, in units of feet. V is defined as the speed of vessel over land minus the current velocity, when traveling with the current, or the speed of vessel over land plus the current velocity, when traveling against the current.
When such conditions (1, 2 and 3 above) exist, the surge and sway forces and the yaw moment acting on the moored vessel shall, as a minimum, be established in accordance with Section 3103F.5.5 or by dynamic analysis.
For MOTs located in ports, the passing distance, L, may be established based on channel width and vessel traffic patterns. The guidelines established in Figure 5-17 of UFC 4-150-06 [5.7] for interior channels may be used. The "vertical bank" in Figure 5-17 of UFC 4-150-06 [5.7] shall be replaced by the side of the moored vessel when establishing the distance, "L."
For MOTs, not located within a port, the distance, "L," must be determined from observed traffic patterns.
The following passing vessel positions shall be investigated:
- Passing vessel is centered on the moored ship. This position produces maximum sway force.
- The midship of the passing vessel is fore or aft of the centerline of the moored ship by a distance of 0.40 times the length of the moored ship. This position is assumed to produce maximum surge force and yaw moment at the same time.
A seiche analysis is required for existing MOTs located within a harbor basin and which have historically experienced seiche. A seiche analysis is required for new MOTs inside a harbor basin prone to penetration of ocean waves.
The standing wave system or seiche is characterized by a series of "nodes" and "antinodes." Seiche typically has wave periods ranging from 20 seconds up to several hours, with wave heights in the range of 0.1 to 0.4 ft [5.7].
The following procedure may be used, as a minimum, in evaluating the effects of seiche within a harbor basin. In more complex cases where the assumptions below are not applicable, dynamic methods are required.
- Calculate the natural period of oscillation of the basin. The basin may be idealized as rectangular, closed or open at the seaward end. Use Chapter 2 of UFC 4-150-06 [5.7] to calculate the wave period and length for different modes. The first three modes shall be considered in the analysis.
- Determine the location of the moored ship with respect to the antinode and node of the first three modes to determine the possibility of resonance.
- Determine the natural period of the vessel and mooring system. The calculation shall be based on the total mass of the system and the stiffness of the mooring lines in surge. The surge motion of the moored vessel is estimated by analyzing the vessel motion as a harmonically forced linear single degree of freedom spring mass system. Methods out-lined in a paper by F.A. Kilner [5.8] can be used to calculate the vessel motion.
- Vessels are generally berthed parallel to the channel; therefore, only longitudinal (surge) motions shall be considered, with the associated mooring loads in the spring lines. The loads on the mooring lines (spring lines) are then determined from the computed vessel motion and the stiffness of those mooring lines.
The kinetic berthing energy demand shall be determined in accordance with Section 3103F.6.
For existing MOTs, the berthing energy capacity shall be calculated as the area under the force-deflection curve for the combined structure and fender system as indicated in Figure 31F-5-5. Fender piles may be included in the lateral analysis to establish the total force-deflection curve for the berthing system. Load-deflection curves for other fender types shall be obtained from manufacturer's data. The condition of fenders shall be taken into account when performing the analysis.
When batter piles are present, the fender system typically absorbs most of the berthing energy. This can be established by comparing the force-deflection curves for the fender system and batter piles. In this case only the fender system energy absorption shall be considered.
A continuous fender system consists of fender piles, chocks, wales, and rubber or spring fender units.
The contact length of a ship during berthing depends on the spacing of the fender piles and fender units, and the connection details of the chocks and wales to the fender piles.
The contact length, Lc, can be calculated using rational analysis considering curvature of the bow and berthing angle.
For discrete fender systems (i.e., not continuous), one fender unit or breasting dolphin shall be able to absorb the entire berthing energy.
The longitudinal and vertical components of the horizontal berthing force shall be calculated using appropriate coefficients of friction between the vessel and the fender. In lieu of as-built data, the values in Table 31F-5-2 may be used for typical fender/vessel materials:
Longitudinal and vertical forces shall be determined by:
For guidelines on new fender designs, refer to UFC 4-152-01 [5.9] and PIANC [5.10]. Velocity and temperature factors, contact angle effects and manufacturing tolerances shall be considered (see Appendices A and B of PIANC [5.10]). Also, see Section 3103F.6.
Guidelines for layout of new MOTs are provided in OCIMF MEG3 [5.4]. The final layout of the mooring and breasting dolphins shall be determined based on the results of the mooring analysis that provides optimal mooring line and breasting forces for the range of vessels to be accommodated.
Offshore MOT moorings shall be designed and analyzed considering the site water depth, metocean environment and class of vessels calling per OCIMF MEG3 [5.4] or UFC 4-159-03 [5.5].
Analysis procedures shall conform to the OCIMF MEG3 [5.4] or UFC 4-159-03 [5.5], and the following:
- A mooring analysis shall be performed for the range of tanker classes and barges calling at each offshore berth.
- Forces acting on moored vessels shall be determined according to Section 3103F.5 and analysis shall consider all possible vessel movements, contribution of buoys, sinkers, catenaries affecting mooring line stiffness and anchorages.
- Correlation of winds, waves and currents shall be considered. The correlation may be estimated by probabilistic analysis of metocean data.
- The actual expected displacement of the vessels shall be used in the analysis.
- Underwater inspections and bathymetry shall be considered.
- Both fully laden and ballast conditions shall be considered.
- Dynamic analysis shall be used to evaluate moorings performance.
Design of mooring components shall be based on loading combinations and safety factors defined in Sections 3103F.8, 3105F.7 and 3105F.8 and follow the guidelines provided in either the OCIMF MEG3 [5.4] or UFC 4-159-03 [5.5].
Safety factors for different material types of mooring lines are given in Table 31F-5-3. The safety factors should be applied to the minimum number of lines specified by the mooring analysis, using the highest loads calculated for the environmental conditions. The minimum breaking load (MBL) of new ropes is obtained from the certificate issued by the manufacturer. If polyamide tails are used in combination with wire mooring lines, the safety factor shall be based on the weaker of the two ropes.
Mooring hardware shall include, but not be limited to, bollards, quick release hooks, other mooring fittings and base bolts. All mooring hardware shall be clearly marked with their safe working loads (or allowable working loads) [5.4]. The certificate issued by the manufacturer normally defines the safe working loads of this hardware.
For new MOTs or berthing systems, a minimum of three quick release hooks are required for each breasting line location for tankers greater than or equal to 50,000 DWT. At least two hooks at each location shall be provided for breasting lines for tankers less than 50,000 DWT. Remote release may be considered for emergency situations.
All hooks and supporting structures shall withstand the minimum breaking load (MBL) of the strongest line with a safety factor of 1.2 or greater. Only one mooring line shall be placed on each quick release hook (N/E).
For multiple quick release hooks, the minimum horizontal load for the design of the tie-down shall be:
Fd = Minimum factored demand for assembly tiedown.
n = Number of hooks on the assembly.
The capacity of the supporting structures must be larger than Fd (See Section 3107F.6).
Other fittings include cleats, bitts and bollards.
If the allowable working loads for existing fittings are not available, the values listed in Table 31F-5-4 may be used for typical sizes, bolt patterns and layout. The allowable working loads are defined for mooring line angles up to 60 degrees from the horizontal. The combination of vertical and horizontal loads shall be considered.
Base bolts are subjected to both shear and uplift. Forces on bolts shall be determined using the following factors:
- Height of load application on bitts or bollards.
- Actual vertical angles of mooring lines for the highest and lowest tide and vessel draft conditions, for all sizes of vessels at each particular berth.
- Actual horizontal angles from the mooring line configurations, for all vessel sizes and positions at each particular berth.
- Simultaneous loads from more than one vessel.
For existing MOTs, the deteriorated condition of the base bolts and supporting members shall be considered in determining the capacity of the fitting.
|α||=||Horizontal mooring line angles|
|θ||=||Vertical mooring line angles|
|B||=||Beam of vessel|
|DWT||=||Dead Weight Tonnage|
|F||=||Longitudinal or vertical component of horizontal normal berthing force|
|Fd||=||Minimum factored demand for assembly tie-down|
|L||=||Distance between passing and moored vessels|
|MBL||=||Minimum breaking load|
|n||=||Number of hooks on the assembly|
|N||=||Maximum horizontal berthing force|
|µ||=||Coefficient of friction of contact materials|
|V||=||Ground speed (knots)|
|Vc||=||Maximum current (knots).|
|Vcrit||=||Ground speed (knots) above which passing loads must be considered|
[5.1] American Concrete Institute (ACI), 2014, ACI 318-14 (ACI 318), "Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14)," Farmington Hills, MI.
[5.2] American Institute of Steel Construction, Inc. (AISC), 2017, AISC 325-17 (AISC 325), "Steel Construction Manual," 15th ed., Chicago, IL.
[5.3] American Wood Council (AWC), 2017, ANSI/AWC NDS-2018 (ANSI/AWC NDS), "National Design Specification (NDS) for Wood Construction," Washington, D.C.
[5.4] Oil Companies International Marine Forum (OCIMF), 2008, "Mooring Equipment Guidelines (MEG3)," 3rd Ed., London, England.
[5.5] Department of Defense, 3 October 2005 (Change 2, 23 June 2016), Unified Facilities Criteria (UFC) 4-159-03, "Design: Moorings," Washington D.C.
[5.6] American Society of Civil Engineers (ASCE), 2016, ASCE/SEI 7-16 (ASCE/SEI 7), "Minimum Design Loads and Associated Criteria for Buildings and Other Structures," Reston, VA.
[5.7] Department of Defense, 12 December 2001 (Change 1, 19 October 2010), Unified Facilities Criteria (UFC) 4-150-06, "Military Harbors and Coastal Facilities," Washington D.C
[5.8] Kilner F.A., 1961, "Model Tests on the Motion of Moored Ships Placed on Long Waves." Proceedings of 7th Conference on Coastal Engineering, August 1960, The Hague, Netherlands, published by the Council on Wave Research - The Engineering Foundation.
[5.9] Department of Defense, 24 January 2017, Unified Facilities Criteria (UFC) 4-152-01, "Design: Piers and Wharves," Washington D.C.
[5.10] Permanent International Association of Navigation Congresses (PIANC), 2002, "Guidelines for the Design of Fender Systems: 2002," Brussels.
Authority: Sections 8750 through 8760, Public Resources Code.
Reference: Sections 8750, 8751, 8755 and 8757, Public Resources Code.
|SITE CLASS||SOIL PROFILE||AVERAGE VALUES FOR TOP 100 FEET OF SOIL PROFILE3|
|Shear Wave Velocity,
|Standard Penetration Test,
|Undrained Shear Strength,
|A||Hard Rock||> 5,000|
|B||Rock||2,500 to 5,000|
|C||Very Stiff/Very Dense Soil and Soft Rock||1,200 to 2,500||> 50||> 2,000|
|D||Soft/Dense Soil Profile||600 to 1,200||15 to 50||1,000 to 2,000|
|E1, 2||Soft/Loose Soil Profile||< 600||< 15||< 1,000|
|F||Defined in Section 3106F.2.1|
- Site Class E also includes any soil profile with more than 10 feet of soft clay (defined as a soil with a plasticity index, PI > 20, water content > 40 percent and Su < 500 psf).
- The plasticity index, P1, and the moisture content shall be determined in accordance with ASTM D4318 [6.1] and ASTM D2216 [6.2], respectively.
- Conversion of CPT data to estimate equivalent Vs, SPT blow count, or Su is allowed.
This section provides minimum standards for analyses and evaluation of geotechnical hazards and foundations under static and seismic conditions.
The requirements provided herein apply to all new and existing MOTs.
Each MOT shall be assigned at least one site class. Site Classes A, B, C, D and E are defined in Table 31F-6-1, and Site Class F is defined by any of the following:
- Soils vulnerable to significant potential loss of stiffness, strength and/or volume under seismic loading due to liquefiable soils, quick and highly sensitive clays and/or collapsible weakly cemented soils.
- Peats and/or highly organic clays, where the thickness of peat or highly organic clay exceeds 10 feet.
- Very high plasticity clays with a plasticity index (PI) greater than 75, where the thickness of clay exceeds 25 feet.
- Very thick soft/medium stiff clays with undrained shear strength less than 1,000 psf, where the thickness of clay exceeds 120 feet.
- Site-specific investigations shall include adequate borings and/or cone penetration tests (CPTs) and other appropriate field methods, to enable the determination of geotechnical parameters.
- Adequate coverage of subsurface data, both horizontally and vertically, shall be obtained to develop geotechnical parameters.
- Exploration shall be deep enough to characterize subsurface materials that are affected by embankment behavior and shall extend to depth of at least 20 feet below the deepest foundation depth.
- During field exploration, particular attention shall be given to the presence of continuous low-strength layers or thin soil layers that could liquefy or weaken during the design earthquake shaking.
- CPTs provide continuous subsurface profile and shall be used to complement exploratory borings. When CPTs are performed, at least one boring shall be performed next to one of the CPT soundings to check that the CPT-soil behavior type interpretations are reasonable for the site. Any difference between CPT interpretation and subsurface condition obtained from borings shall be reconciled.
- Quantitative site soil stratigraphy is required to a depth of 100 feet for assigning a site class (see Table 31F-6-1).
- Laboratory tests may be necessary to supplement the borings and insitu field tests.
Section 3103F.4 defines the earthquake loads to be used for structural and geotechnical evaluations in terms of design Peak Ground Accelerations (PGA), spectral accelerations and design earthquake magnitude. Values used for analyses are based on Probabilistic Seismic Hazard Analyses (PSHA) using two levels of seismic performance criteria (Section 3104F.2.1 and Table 31F-4-1).
The liquefaction potential of the soils in the immediate vicinity of or beneath each MOT, and associated slopes, embankments or rock dikes shall be evaluated for the PGAs associated with seismic performance Levels 1 and 2. Liquefaction potential evaluation should follow the procedures outlined in NCEER report [6.3], SCEC [6.4] and CGS Special Publication 117A [6.5].
If liquefaction is shown to be initiated in the above evaluations, the particular liquefiable strata and their thicknesses shall be clearly shown on site profiles. Resulting hazards associated with liquefaction shall be addressed including translational or rotational deformations of slopes or embankment systems and post liquefaction settlement of slopes or embankment systems and underlying foundation soils, as noted below. If such analyses indicate the potential for partial or gross (flow) failure of a slope or embankment, adequate evaluations shall be performed to confirm such a condition exists, together with analyses to evaluate potential slope displacements (lateral spreads). In these situations and for projects where more detailed numerical analyses are performed, a peer review (see Section 3101F.8.2) may be required.
Static stability analysis using conventional limit equilibrium methods shall be performed for site related slope or embankment systems. Live load surcharge shall be considered in analyses based on project-specific information. The long-term static factor of safety of the slope or embankment shall not be less than 1.5.
Pseudo-static seismic slope or embankment stability analyses shall be performed to estimate the horizontal yield acceleration for the slope for the Level 1 and Level 2 earthquakes. During the seismic event, appropriate live load surcharge shall be considered.
If liquefaction and/or strength loss of the site soils is likely, the following shall be used in the analyses, as appropriate:
- Residual strength of liquefied soils
- Strengths compatible with the pore-pressure generation of potentially liquefiable soils
- Potential strength reduction of clays
The residual strength of liquefied soils shall be estimated using guidelines outlined in SCEC [6.4] or other appropriate documents as noted in CGS Special Publication 117A [6.5].
Pseudo-static analysis shall be performed without considering the presence of the foundation system. Using a horizontal seismic coefficient of one-half of the PGA, if the estimated factor of safety is greater than or equal to 1.1, then no further evaluation of lateral spreading or kinematic loading from lateral spreading is required.
The static factor of safety immediately following a design earthquake event shall not be less than 1.1 when any of the following are used in static stability analysis:
The earthquake—induced lateral deformations of the slope or embankment and associated foundations soils shall be determined for the Level 1 and Level 2 earthquakes using the associated PGA at the ground surface (not modified for liquefaction). If liquefaction and/or strength loss of the site soils is likely, the following shall be used in the analyses, as appropriate:
- Residual strength of liquefied soils
- Strengths compatible with the pore-pressure generation of potentially liquefiable soils
- Potential strength reduction of clays
The presence of the foundation system shall not be included in the "free field" evaluations.
Initial lateral spread estimates shall be made using the Newmark displacement approach documented in NCHRP Report 611 [6.6] or other appropriate but similar procedures.
Seismically induced settlement shall be evaluated. Based on guidelines outlined in SCEC [6.4] or other appropriate documents such as CGS Special Publication 117A [6.5]. If seismically induced settlement is anticipated, the resulting design impacts shall be considered, including the potential development of downdrag loads on piles.
Both static and seismic earth pressures acting on MOT structures shall be evaluated.
The effect of static active earth pressures on structures resulting from static loading of backfill soils shall be considered where appropriate. Backfill sloping configuration, if applicable, and backland loading conditions shall be considered in the evaluations. The loading considerations shall be based on project-specific information. The earth pressures under static loading should be based on guidelines outlined in NAVFAC DM7-02 [6.7] or other appropriate documents.
The effect of earth pressures on structures resulting from seismic loading of backfill soils, including the effect of porewater pressure build-up in the backfill, shall be considered. The seismic coefficients used for this analysis shall be based on the Level 1 and Level 2 earthquake PGA values.
Evaluation of earth pressures under seismic loading, should be based on NCHRP Report 611 [6.6] or other appropriate methods.
Axial geotechnical capacity of piles under static loading shall be evaluated using guidelines for estimating axial pile capacities provided in POLB WDC [6.8] or other appropriate documents. A minimum factor of safety of 2.0 shall be achieved on the ultimate capacity of the pile using appropriate MOT loading.
If liquefaction or seismically-induced settlement is anticipated, the ultimate axial geotechnical capacity of piles under seismic conditions shall be evaluated for the effects of liquefaction and/or downdrag forces on the pile. The ultimate geotechnical capacity of the pile during liquefaction shall be determined on the basis of the residual strength of the soil for those layers where the factor of safety for liquefaction is determined to be less than 1.0.
When seismically-induced settlements are predicted to occur during design earthquakes, the downdrag loads shall be computed, and the combination of downdrag load and static load determined. Only the tip resistance of the pile and the side friction resistance below the lowest layer contributing to the downdrag shall be used in the capacity evaluation. The ultimate axial geotechnical capacity of the pile shall not be less than the combination of the seismically induced downdrag force and the maximum static load.
The geotechnical analyst (see Section 3102F.3.4.8) shall coordinate with the structural analyst (see Section 3102F.3.4.4) and develop axial springs (T-z) for piles. The T-z springs may be developed either at the top or at the tip of the pile (see Figure 31F-6-1). If the springs are developed at the pile tip, the tip shall include both the friction resistance along the pile (i.e., side springs [t-z]) and tip resistance at the pile tip (i.e. tip springs [q-w]), as illustrated in Figure 31F-6-1. If T-z springs are developed at the pile top, the appropriate elastic shortening of the pile shall be included in the springs. Linear or nonlinear springs may be developed if requested by the structural analyst.
Due to the uncertainties associated with the development of axial springs, such as the axial soil capacities, load distributions along the piles and simplified spring stiffnesses, both upper-bound and lower-bound limits shall be estimated and utilized in the analyses.
For design of piles under loading associated with the inertial response of the superstructure, level-ground inelastic lateral springs (p-y) shall be developed. The lateral springs within the shallow portion of the piles (generally within 10 pile diameters below the ground surface) tend to dominate the inertial behavior. Geotechnical parameters for developing lateral soil springs shall follow guidelines provided in API RP 2A-WSD [6.9] or other appropriate documents.
Due to uncertainties associated with the development of p-y curves for dike structures, upper-bound and lower-bound p-y springs shall be developed for use in superstructure inertial response analyses.
Two separate loading conditions for the piles shall be considered:
- Inertial loading under seismic conditions
- Kinematic loading from lateral ground spreading
Inertial loading is associated with earthquake-induced lateral loading on a structure, while kinematic loading refers to loading on foundation piles from earthquake induced lateral deformations of the slope/embankment/dike system. Simultaneous application of these loading conditions shall be evaluated with due consideration of the phasing and locations of these loads on foundation elements. The foundation shall be designed such that the structural performance is acceptable when subjected to both inertial and kinematic loadings.
The lateral soil springs shall be used in inertial loading response analyses. The evaluation of inertial loading can be performed by ignoring potential slope/embankment/dike system deformations (i.e., one end of the lateral soil spring at a given depth is attached to the corresponding pile node and the other end is assumed fixed).
Kinematic pile loading from permanent lateral spread ground deformation in deep seated levels of slope/embankment/dike foundation soils shall be evaluated. The lateral deformations shall be restricted such that the structural performance of foundation piles is not compromised.
The lateral deformation of the embankment or dike and associated piles and foundation soils shall be determined using analytical methods as follows:
- Initial estimates of free field lateral spread deformations (in the absence of piles) may be determined using the simplified Newmark sliding block method as described in Section 3106F.5.4. The geotechnical analyst shall provide the structural analyst with level-ground p-y curves for the weak soil layer controlling the lateral spread and soil layers above and below the weak layer. Appropriate overburden pressures shall be used in simplified pushover analyses, to estimate the pile displacement capacities and corresponding pile shear within the weak soil zone.
- For the pushover analysis, the estimated displacements may be uniformly distributed within the thickness of the weak soil layer (i.e., zero at and below the bottom of the layer to the maximum value at and above the top of the weak layer). The thickness of the weak soil layer used in the analysis (failure zone) shall not be more than five times the pile diameter or 10 feet, whichever is smaller.
- For a simplified analysis (see Figure 31F-6-2), the pile shall be fixed against rotation and translation relative to the soil displacement at some distance above and below the weak soil layer. Between these two points, lateral soil springs are provided, which allow deformation of the pile relative to the deformed soil profile.
Shallow foundations shall be assumed to move with the ground. Springs and dashpots may be evaluated as per Gazetas [6.10].
Buried flexible structures or buried portions of flexible structures including piles and pipelines shall be assumed to deform with estimated ground movement at depth.
As the soil settles, it shall be assumed to apply shear forces to buried structures or buried portions of structures including deep foundations.
Geotechnical evaluations of underwater pipelines shall include static stability of the seafloor ground supporting the pipeline and settlement and lateral deformation of the ground under earthquakes. If the pipeline is buried, the potential for uplift of the pipeline under earthquakes shall also be evaluated.