CODES

ADOPTS WITH AMENDMENTS:

International Building Code 2015 (IBC 2015)

Copyright

Preface

Acknowledgements

California Code of Regulations, Title 24

How to Distinguish Between Model Code Language and California Amendments

Effective Use of the International Building Code

Chapter 16 Structural Design

Chapter 16A Structural Design

Chapter 17 Special Inspections and Tests

Chapter 17A Special Inspections and Tests

Chapter 18 Soils and Foundations

Chapter 18A Soils and Foundations

Chapter 19 Concrete

Chapter 19A Concrete

Chapter 20 Aluminum

Chapter 21 Masonry

Chapter 21A Masonry

Chapter 22 Steel

Chapter 22A Steel

Chapter 23 Wood

Chapter 24 Glass and Glazing

Chapter 25 Gypsum Board, Gypsum Panel Products and Plaster

Chapter 26 Plastic

Chapter 27 Electrical

Chapter 28 Mechanical Systems

Chapter 29 Plumbing Systems

Chapter 30 Elevators and Conveying Systems

Chapter 31 Special Construction

Chapter 31A Systems for Window Cleaning or Exterior Building Maintenance

Chapter 31B [DPH] Public Pools

Chapter 31C [DPH] Radiation

Chapter 31D [DPH] Food Establishments

Chapter 31E Reserved

Chapter 31F [SLC] Marine Oil Terminals

Chapter 32 Encroachments Into the Public Right-Of-Way

Chapter 33 Safeguards During Construction

Chapter 34 Reserved

Chapter 34A Existing Structures

Chapter 35 Referenced Standards

Appendix A Employee Qualifications

Appendix B Board of Appeals

Appendix C Group U—agricultural Buildings

Appendix D Fire Districts

Appendix E Reserved

Appendix F Rodentproofing

Appendix G Flood-Resistant Construction

Appendix H Signs

History Note Appendix

Appendix I Patio Covers

Appendix J Grading

Appendix K Group R-3 and Group R-3.1 Occupancies Protected by the Facilities of the Central Valley Flood Protection Plan

Appendix L Earthquake Recording Instrumentation

Appendix M Tsunami-Generated Flood Hazard

The provisions of this chapter shall govern the structural design of buildings, structures and portions thereof regulated by this code.

The scope of application of Chapter 16A is as follows:

  1. Applications listed in Section 1.9.2.1, regulated by the Division of the State Architect-Structural Safety (DSASS). These applications include public elementary and secondary schools, community colleges and state-owned or state-leased essential services buildings.
  2. Applications listed in Sections 1.10.1 and 1.10.4, regulated by the Office of Statewide Health Planning and Development (OSHPD). These applications include hospitals, skilled nursing facilities, intermediate care facilities, and correctional treatment centers.

    Exception: [OSHPD 2] Single-story Type V skilled nursing or intermediate care facilities utilizing wood-frame or light-steel-frame construction as defined in Health and Safety Code Section 129725, which shall comply with Chapter 16 and any applicable amendments therein.

DSA-SS and OSHPD adopt this chapter and all amendments.

Exception: Amendments adopted by only one agency appear in this chapter preceded with the appropriate acronym of the adopting agency, as follows:

  1. Division of the State Architect-Structural Safety:

    [DSA-SS] – For applications listed in Section 1.9.2.1.

  2. Office of Statewide Health Planning and Development:

    [OSHPD 1] – For applications listed in Section 1.10.1.

    [OSHPD 4] – For applications listed in Section 1.10.4.

In addition to the requirements of the California Administrative Code and the California Building Code, any aspect of project design, construction, quality assurance or quality control programs for which this code requires approval by the Registered Design Professional (RDP), are also subject to approval by the enforcement agency.

The following terms are defined in Chapter 2 except those defined below, which shall, for the purposes of this section, have the meanings shown herein.

ALLOWABLE STRESS DESIGN.

DEAD LOADS.

DESIGN STRENGTH.

DIAPHRAGM.

  • Diaphragm, blocked.
  • Diaphragm boundary.
  • Diaphragm chord.

ESSENTIAL FACILITIES.

FABRIC PARTITION.

FACTORED LOAD.

HELIPAD.

ICE-SENSITIVE STRUCTURE.

IMPACT LOAD.

LIMIT STATE.

LIVE LOAD.

LIVE LOAD (ROOF).

LOAD AND RESISTANCE FACTOR DESIGN (LRFD).

LOAD EFFECTS.

LOAD FACTOR.

LOADS.

NOMINAL LOADS.

OTHER STRUCTURES.

PANEL (PART OF A STRUCTURE).

RESISTANCE FACTOR.

RISK CATEGORY.

STRENGTH, NOMINAL.

STRENGTH, REQUIRED.

STRENGTH DESIGN.

SUSCEPTIBLE BAY.

VEHICLE BARRIER.

NOTATIONS.

D=Dead load.
Di=Weight of ice in accordance with Chapter 10 of ASCE 7.
E=Combined effect of horizontal and vertical earthquake induced forces as defined in Section 12.4.2 of ASCE 7.
F=Load due to fluids with well-defined pressures and maximum heights.
Fa=Flood load in accordance with Chapter 5 of ASCE 7.
H=Load due to lateral earth pressures, ground water pressure or pressure of bulk materials.
L=Roof live load greater than 20 psf (0.96 kN/m2) and floor live load.
Lr=Roof live load of 20 psf (0.96 kN/m2) or less. R = Rain load.
S=Snow load.
T=Self-straining load.
Vasd=Nominal design wind speed (3-second gust), miles per hour (mph) (km/hr) where applicable.
Vult=Ultimate design wind speeds (3-second gust), miles per hour (mph) (km/hr) determined from Figure 1609.3(1), 1609.3(2), 1609.3(3) or ASCE 7.
W=Load due to wind pressure.
Wi=Wind-on-ice in accordance with Chapter 10 of ASCE 7.

Construction documents shall show the size, section and relative locations of structural members with floor levels, column centers and offsets dimensioned. The design loads and other information pertinent to the structural design required by Sections 1603A.1.1 through 1603A.1.9 shall be indicated on the construction documents.

Exception: Construction documents for buildings constructed in accordance with the conventional light-frame construction provisions of Section 2308 shall indicate the following structural design information:

  1. Floor and roof live loads.
  2. Ground snow load, Pg.
  3. Ultimate design wind speed, Vult, (3-second gust), miles per hour (mph) (km/hr) and nominal design wind speed, Vasd, as determined in accordance with Section 1609.3.1 and wind exposure.
  4. Seismic design category and site class.
  5. Flood design data, if located in flood hazard areas established in Section 1612A.3.
  6. Design load-bearing values of soils.

[DSA-SS] Additional requirements are included in Section 4-210 and 4-317 of the California Administrative Code (Part 1, Title 24, C.C.R).

[OSHPD 1] Additional requirements are included in Section 7-115 and 7-125 of the California Administrative Code.

The uniformly distributed, concentrated and impact floor live load used in the design shall be indicated for floor areas. Use of live load reduction in accordance with Section 1607A.10 shall be indicated for each type of live load used in the design.
The roof live load used in the design shall be indicated for roof areas (Section 1607A.12).

The ground snow load, Pg, shall be indicated. In areas where the ground snow load, Pg, exceeds 10 pounds per square foot (psf) (0.479 kN/m2), the following additional information shall also be provided, regardless of whether snow loads govern the design of the roof:

  1. Flat-roof snow load, Pf.
  2. Snow exposure factor, Ce.
  3. Snow load importance factor, Is.
  4. Thermal factor, Ct.
  5. Drift surcharge load(s), Pd, where the sum of Pd and Pf exceeds 20 psf (0.96 kN/m2).
  6. Width of snow drift(s), w.

The following information related to wind loads shall be shown, regardless of whether wind loads govern the design of the lateral force-resisting system of the structure:

  1. Ultimate design wind speed, Vult, (3-second gust), miles per hour (km/hr) and nominal design wind speed, Vasd, as determined in accordance with Section 1609A.3.1.
  2. Risk category.
  3. Wind exposure. Applicable wind direction if more than one wind exposure is utilized.
  4. Applicable internal pressure coefficient.
  5. Design wind pressures to be used for exterior component and cladding materials not specifically designed by the registered design professional responsible for the design of the structure, psf (kN/m2).

The following information related to seismic loads shall be shown, regardless of whether seismic loads govern the design of the lateral force-resisting system of the structure:

  1. Risk category.
  2. Seismic importance factor, Ie.
  3. Mapped spectral response acceleration parameters, SS and S1.
  4. Site class.
  5. Design spectral response acceleration parameters, SDS and SD1.
  6. Seismic design category.
  7. Basic seismic force-resisting system(s).
  8. Design base shear(s).
  9. Seismic response coefficient(s), CS.
  10. Response modification coefficient(s), R.
  11. Analysis procedure used.
  12. Applicable horizontal structural irregularities.
  13. Applicable vertical structural irregularities.
  14. Location of base as defined in Section 1613A.2.

Connections that resist design seismic forces shall be designed and detailed on the design drawings.

The design load-bearing values of soils shall be shown on the construction documents.

For buildings located in whole or in part in flood hazard areas as established in Section 1612A.3, the documentation pertaining to design, if required in Section 1612A.5, shall be included and the following information, referenced to the datum on the community’s Flood Insurance Rate Map (FIRM), shall be shown, regardless of whether flood loads govern the design of the building:

  1. Flood design class assigned according to ASCE 24.
  2. In flood hazard areas other than coastal high hazard areas or coastal A zones, the elevation of the proposed lowest floor, including the basement.
  3. In flood hazard areas other than coastal high hazard areas or coastal A zones, the elevation to which any nonresidential building will be dry floodproofed.
  4. In coastal high hazard areas and coastal A zones, the proposed elevation of the bottom of the lowest horizontal structural member of the lowest floor, including the basement.
Special loads that are applicable to the design of the building, structure or portions thereof shall be indicated along with the specified section of this code that addresses the special loading condition.
The dead load of rooftop-mounted photovoltaic panel systems, including rack support systems, shall be indicated on the construction documents.

Where unusual erection or construction procedures are considered essential by the Registered Design Professional (RDP) in order to accomplish the intent of the design or influence the construction, such procedure shall be indicated on the construction documents.

Geotechnical and geohazard reports for review by the enforcement agency shall be accompanied by a description of the project prepared by the registered design professional (RDP) in responsible charge, which shall include the following:

  1. Type of service such as general acute care facility, skilled nursing facility, intermediate care facility, acute psychiatric facility, central utility plants, K-12 school, community college, essential services, etc.
  2. Construction materials used for the project such as steel, concrete. masonry, wood, etc.
  3. Type of construction project such as new, addition, alteration, repair, etc.
  4. For existing buildings, extent of construction such as incidental, minor, major, and/or voluntary seismic improvements as defined in Section 318, Part 10, Title 24, C.C.R. [DSA-SS] Sections 202 and 3402A [OSHPD 1 & 4].
  5. Seismic force resisting system used for each structure in the project.
  6. Foundation system that will be used for each structure in the project such as spread footing, drilled piers, etc.
  7. Analysis procedure used and basis of design such as ASCE 7 Equivalent Lateral Force Procedure, ASCE 41 Nonlinear Dynamic Procedure, etc.
  8. Building characteristics such as number of stories above and below grade, foot print area at grade, grade slope on site, etc.
  9. Special features such as requirement for shoring, underpinning, retaining walls, etc.

The application for the approval of construction documents that involves structural elements or components shall be accompanied by complete and accurate structural design computations, which shall comply with requirements prescribed by the enforcement agency:

  1. The computations shall be preceded by a detailed index.
  2. The computations including each major subsection shall be prefaced by a statement clearly and concisely outlining the basis for the structural design and indicating the manner in which the structure will resist the vertical loads and lateral forces.
  3. The computations shall be sufficiently complete to the extent that calculations for the individual structural members and connections can be readily interpreted.
Building, structures and parts thereof shall be designed and constructed in accordance with strength design, load and resistance factor design, allowable stress design, empirical design or conventional construction methods, as permitted by the applicable material chapters.

Buildings and other structures, and parts thereof, shall be designed and constructed to support safely the factored loads in load combinations defined in this code without exceeding the appropriate strength limit states for the materials of construction. Alternatively, buildings and other structures, and parts thereof, shall be designed and constructed to support safely the nominal loads in load combinations defined in this code without exceeding the appropriate specified allowable stresses for the materials of construction.

Loads and forces for occupancies or uses not covered in this chapter shall be subject to the approval of the building official.

Structural systems and members thereof shall be designed to have adequate stiffness to limit deflections and lateral drift. See Section 12.12.1 of ASCE 7 for drift limits applicable to earthquake loading.

TABLE 1604A.3

DEFLECTION LIMITSa, b, c, h, i

CONSTRUCTIONL or LrE, S or WfD + (L or Lr) d, g
Roof members:e
Supporting plaster or stucco ceilingl/360l/360l/240
Supporting nonplaster ceilingl/240l/240l/180
Not supporting ceilingl/180l/180l/120
Floor membersl/360l/240
Exterior walls:
With plaster or stucco finishesl/360
With other brittle finishesl/240
With flexible finishesl/120
Veneered walls, anchored veneers and adhered veneers over 1 inch (25 mm) thick, including the mortar backingl/600
Interior partitions:b
With plaster or stucco finishesl/360
With other brittle finishesl/240
With flexible finishesl/120
Farm buildingsl/180
Greenhousesl/120

For SI: 1 foot = 304.8 mm.

  1. For structural roofing and siding made of formed metal sheets, the total load deflection shall not exceed 1/60. For secondary roof structural members supporting formed metal roofing, the live load deflection shall not exceed 1/150. For secondary wall members supporting formed metal siding, the design wind load deflection shall not exceed 1/90. For roofs, this exception only applies when the metal sheets have no roof covering.
  2. Flexible, folding and portable partitions are not governed by the provisions of this section. The deflection criterion for interior partitions is based on the horizontal load defined in Section 1607.14.
  3. See Section 2403 for glass supports.
  4. The deflection limit for the D+L load combination only applies to the deflection due to the creep component of long-term dead load deflection plus the short-term live load deflection. For wood structural members that are dry at time of installation and used under dry conditions in accordance with the AWC NDS, the creep component of the long-term deflection shall be permitted to be estimated as the immediate dead load deflection resulting from 0.5D. For wood structural members at all other moisture conditions, the creep component of the long-term deflection is permitted to be estimated as the immediate dead load deflection resulting from D. The value of 0.5D shall not be used in combination with AWC NDS provisions for long-term loading.
  5. The above deflections do not ensure against ponding. Roofs that do not have sufficient slope or camber to ensure adequate drainage shall be investigated for ponding. See Section 1611 for rain and ponding requirements and Section 1503.4 for roof drainage requirements.
  6. The wind load is permitted to be taken as 0.42 times the “component and cladding” loads for the purpose of determining deflection limits herein. Where members support glass in accordance with Section 2403 using the deflection limit therein, the wind load shall be no less than 0.6 times the “component and cladding” loads for the purpose of determining deflection.
  7. For steel structural members, the dead load shall be taken as zero.
  8. For aluminum structural members or aluminum panels used in skylights and sloped glazing framing, roofs or walls of sunroom additions or patio covers not supporting edge of glass or aluminum sandwich panels, the total load deflection shall not exceed 1/60. For continuous aluminum structural members supporting edge of glass, the total load deflection shall not exceed 1/175 for each glass lite or 1/60 for the entire length of the member, whichever is more stringent. For aluminum sandwich panels used in roofs or walls of sunroom additions or patio covers, the total load deflection shall not exceed 1/120.
  9. For cantilever members, 1 shall be taken as twice the length of the cantilever.
The deflections of structural members shall not exceed the more restrictive of the limitations of Sections 1604A.3.2 through 1604A.3.5 or that permitted by Table 1604A.3.
The deflection of reinforced concrete structural members shall not exceed that permitted by ACI 318.
The deflection of steel structural members shall not exceed that permitted by AISC 360, AISI S100, ASCE 8, SJI CJ, SJI JG, SJI K or SJI LH/DLH, as applicable.
The deflection of masonry structural members shall not exceed that permitted by TMS 402/ACI 530/ASCE 5.
The deflection of aluminum structural members shall not exceed that permitted by AA ADM1.
The deflection limits of Section 1604A.3.1 shall be used unless more restrictive deflection limits are required by a referenced standard for the element or finish material.

The maximum span-depth ratio for any roof or floor diaphragm consisting of steel and composite steel slab decking shall not exceed those given in Table 1604A.4, unless test data and design calculations acceptable to the enforcement agency are submitted and approved for the use of other span-depth ratios. Concrete diaphragms shall not exceed the span depth ratios for the equivalent composite steel-slab diaphragm in Table 1604A.4.

Deflection criteria for materials not specified shall be developed by the project architect or structural engineer in a manner consistent with the provisions of this section and approved by the enforcement agency.

Load effects on structural members and their connections shall be determined by methods of structural analysis that take into account equilibrium, general stability, geometric compatibility and both short- and long-term material properties.

Members that tend to accumulate residual deformations under repeated service loads shall have included in their analysis the added eccentricities expected to occur during their service life.

Any system or method of construction to be used shall be based on a rational analysis in accordance with well-established principles of mechanics. Such analysis shall result in a system that provides a complete load path capable of transferring loads from their point of origin to the load-resisting elements.

The total lateral force shall be distributed to the various vertical elements of the lateral force-resisting system in proportion to their rigidities, considering the rigidity of the horizontal bracing system or diaphragm. Rigid elements assumed not to be a part of the lateral force-resisting system are permitted to be incorporated into buildings provided their effect on the action of the system is considered and provided for in the design. Structural analysis shall explicitly include consideration of stiffness of diaphragms in accordance with ASCE 7 Section 12.3.1. Where required by ASCE 7, provisions shall be made for the increased forces induced on resisting elements of the structural system resulting from torsion due to eccentricity between the center of application of the lateral forces and the center of rigidity of the lateral force-resisting system.

Every structure shall be designed to resist the overturning effects caused by the lateral forces specified in this chapter.

See Section 1609A for wind loads, Section 1610A for lateral soil loads and Section 1613A for earthquake loads.

TABLE 1604A.4

MAXIMUM HORIZONTAL DIAPHRAGM SPAN AND SPAN-DEPTH RATIOS1, 3, 4

FLEXIBILITY FACTOR(F)2MAXIMUM DIAPHRAGM SPAN FOR MASONRY OR CONCRETE WALLS (feet)DIAPHRAGM SPAN-DEPTH LIMITATION
Rotation (torsion) Not Considered in DiaphragmRotation (torsion) Considered in Diaphragm
Masonry or Concrete WallsFlexible WallsMasonry or Concrete WallsFlexible Walls
More than 150Not to be usedNot to be used2:1Not to be used11/2:1
70-1502002:1 or as required for deflection3:1Not to be used2:1
10-7040021/2:1 or as required for deflection4:1As required for deflection21/2:1
1-10No limitation3:1 or as required for deflection5:1As required for deflection3:1
Less than 1No limitationAs required for deflectionNo limitationAs required for deflection31/2:1

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 plf = 14.594 N/m, 1 psi = 6894 Pa

  1. Diaphragms shall satisfy span-depth limitations based on flexibility.
  2. Flexibility factor (F) is the average deflection in micro inches (10-6) or μm of the diaphragm web per foot (m) of span stressed with a shear of 1 pound per foot (N/m).
  3. The total deflection Δ of the diaphragm may be computed from the equation: Δ = Δf + Δ w.

    Where:

    Δf = Flexural deflection of the diaphragm determined in the same manner as the deflection of beams. The flexural stiffness of the web of diaphragms consisting of bare steel decking shall be neglected.

    Δw = Web deflection of the diaphragm may be determined solving the following equation:

    Where:

    L = Distance in feet (m) between the vertical resisting element (such as a shear wall) and the point to which the deflection is to be determined.

    qave = Average shear in the diaphragm in pounds per foot (N/m) over length L.

  4. When applying these limitations to cantilevered diaphragms, the allowable span-depth ratio will be half of that shown.

Each building and structure shall be assigned a risk category in accordance with Table 1604.5. Where a referenced standard specifies an occupancy category, the risk category shall not be taken as lower than the occupancy category specified therein. Where a referenced standard specifies that the assignment of a risk category be in accordance with ASCE 7, Table 1.5-1, Table 1604.5 shall be used in lieu of ASCE 7, Table 1.5-1.

TABLE 1604A.5

RISK CATEGORY OF BUILDINGS AND OTHER STRUCTURES

RISK CATEGORYNATURE OF OCCUPANCY
IBuildings and other structures that represent a low hazard to human life in the event of failure, including but not limited to:
  • Agricultural facilities.
  • Certain temporary facilities.
  • Minor storage facilities.
IIBuildings and other structures except those listed in Risk Categories I, III and IV.
IIIBuildings and other structures that represent a substantial hazard to human life in the event of failure, including but not limited to:
  • Buildings and other structures whose primary occupancy is public assembly with an occupant load greater than 300.
  • Buildings and other structures containing Group E occupancies with an occupant load greater than 250.
  • Buildings and other structures containing educational occupancies for students above the 12th grade with an occupant load greater than 500.
  • Group I-3 occupancies.
  • Any other occupancy with an occupant load greater than 5,000.a
  • Power-generating stations, water treatment facilities for potable water, wastewater treatment facilities and other public utility facilities not included in Risk Category IV.
  • Buildings and other structures not included in Risk Category IV containing quantities of toxic or explosive materials that:

    • Exceed maximum allowable quantities per control area as given in Table 307.1(1) or 307.1(2) or per outdoor control area in accordance with the California Fire Code; and
    • Are sufficient to pose a threat to the public if released.b
IVBuildings and other structures designated as essential facilities, including but not limited to:
  • [OSHPD 1 & 4] Hospital Buildings as defined in the California Administrative Code, Section 7-111 and all structures required for their continuous operation or access/egress.
  • Fire, rescue, ambulance and police stations and emergency vehicle garages.
  • Designated earthquake, hurricane or other emergency shelters.
  • Designated emergency preparedness, communications and operations centers and other facilities required for emergency response [DSA-SS] as defined in the California Administrative Code (Title 24, Part 1, CCR) Section 4-207 and all structures required for their continuous operation or access/egress.
  • Power-generating stations and other public utility facilities required as emergency backup facilities for Risk Category IV structures.
  • Buildings and other structures containing quantities of highly toxic materials that:

    • Exceed maximum allowable quantities per control area as given in Table 307.1(2) or per outdoor control area in accordance with the California Fire Code; and
    • Are sufficient to pose a threat to the public if released.b
  • Aviation control towers, air traffic control centers and emergency aircraft hangars.
  • Buildings and other structures having critical national defense functions.
  • Water storage facilities and pump structures required to maintain water pressure for fire suppression.
  1. For purposes of occupant load calculation, occupancies required by Table 1004.1.2 to use gross floor area calculations shall be permitted to use net floor areas to determine the total occupant load.
  2. Where approved by the building official, the classification of buildings and other structures as Risk Category III or IV based on their quantities of toxic, highly toxic or explosive materials is permitted to be reduced to Risk Category II, provided it can be demonstrated by a hazard assessment in accordance with Section 1.5.3 of ASCE 7 that a release of the toxic, highly toxic or explosive materials is not sufficient to pose a threat to the public.
Where a building or structure is occupied by two or more occupancies not included in the same risk category, it shall be assigned the classification of the highest risk category corresponding to the various occupancies. Where buildings or structures have two or more portions that are structurally separated, each portion shall be separately classified. Where a separated portion of a building or structure provides required access to, required egress from or shares life safety components with another portion having a higher risk category, both portions shall be assigned to the higher risk category.
The building official is authorized to require an engineering analysis or a load test, or both, of any construction whenever there is reason to question the safety of the construction for the intended occupancy. Engineering analysis and load tests shall be conducted in accordance with Section 1709A.
Materials and methods of construction that are not capable of being designed by approved engineering analysis or that do not comply with the applicable referenced standards, or alternative test procedures in accordance with Section 1707A, shall be load tested in accordance with Section 1710A.
Buildings and other structures, and portions thereof, shall be provided with anchorage in accordance with Sections 1604A.8.1 through 1604A.8.3, as applicable.
Anchorage of the roof to walls and columns, and of walls and columns to foundations, shall be provided to resist the uplift and sliding forces that result from the application of the prescribed loads.
Walls that provide vertical load-bearing resistance or lateral shear resistance for a portion of the structure shall be anchored to the roof and to all floors and members that provide lateral support for the wall or that are supported by the wall. The connections shall be capable of resisting the horizontal forces specified in Section 1.4.5 of ASCE 7 for walls of structures assigned to Seismic Design Category A and to Section 12.11 of ASCE 7 for walls of structures assigned to all other seismic design categories. For anchorage of concrete or masonry walls to roof and floor diaphragms, the out-of-plane strength design force shall not be less than 280 lb/linear ft (4.09 kN/m) of wall. Required anchors in masonry walls of hollow units or cavity walls shall be embedded in a reinforced grouted structural element of the wall. See Sections 1609A for wind design requirements and 1613A for earthquake design requirements.

Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. Connections of decks with cantilevered framing members to exterior walls or other framing members shall be designed for both of the following:

  1. The reactions resulting from the dead load and live load specified in Table 1607A.1, or the snow load specified in Section 1608A, in accordance with Section 1605A, acting on all portions of the deck.
  2. The reactions resulting from the dead load and live load specified in Table 1607A.1, or the snow load specified in Section 1608A, in accordance with Section 1605A, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck.
Structural members, systems, components and cladding shall be designed to resist forces due to earthquakes and wind, with consideration of overturning, sliding and uplift. Continuous load paths shall be provided for transmitting these forces to the foundation. Where sliding is used to isolate the elements, the effects of friction between sliding elements shall be included as a force.
Lateral force-resisting systems shall meet seismic detailing requirements and limitations prescribed in this code and ASCE 7, excluding Chapter 14 and Appendix 11A, even when wind load effects are greater than seismic load effects.

Buildings and other structures and portions thereof shall be designed to resist:

  1. The load combinations specified in Section 1605A.2, 1605A.3.1 or 1605A.3.2;
  2. The load combinations specified in Chapters 18 through 23; and
  3. The seismic load effects including overstrength factor in accordance with Section 12.4.3 of ASCE 7 where required by Section 12.2.5.2, 12.3.3.3 or 12.10.2.1 of ASCE 7. With the simplified procedure of ASCE 7 Section 12.14, the seismic load effects including over-strength factor in accordance with Section 12.14.3.2 of ASCE 7 shall be used.

Applicable loads shall be considered, including both earthquake and wind, in accordance with the specified load combinations. Each load combination shall also be investigated with one or more of the variable loads set to zero.

Where the load combinations with overstrength factor in Section 12.4.3.2 of ASCE 7 apply, they shall be used as follows:

  1. The basic combinations for strength design with over-strength factor in lieu of Equations 16A-5 and 16A-7 in Section 1605A.2.
  2. The basic combinations for allowable stress design with overstrength factor in lieu of Equations 16A-12, 16A-14 and 16A-16 in Section 1605A.3.1.
  3. The basic combinations for allowable stress design with overstrength factor in lieu of Equations 16A-21 and 16A-22 in Section 1605A.3.2.
Regardless of which load combinations are used to design for strength, where overall structure stability (such as stability against overturning, sliding, or buoyancy) is being verified, use of the load combinations specified in Section 1605A.2 or 1605A.3 shall be permitted. Where the load combinations specified in Section 1605A.2 are used, strength reduction factors applicable to soil resistance shall be provided by a registered design professional. The stability of retaining walls shall be verified in accordance with Section 1807A.2.3. When using allowable stress design, factor of safety for soil bearing values shall not be less than the overstrength factor of the structures supported.

Where strength design or load and resistance factor design is used, buildings and other structures, and portions thereof, shall be designed to resist the most critical effects resulting from the following combinations of factored loads:

(Equation 16A-1)

(Equation 16A-2)

(Equation 16A-3)

(Equation 16A-4)

(Equation 16A-5)

(Equation 16A-6)

(Equation 16A-7)

where:

f1 = 1 for places of public assembly live loads in excess of 100 pounds per square foot (4.79 kN/m2), and parking garages; and 0.5 for other live loads.

f2 = 0.7 for roof configurations (such as saw tooth) that do not shed snow off the structure, and 0.2 for other roof configurations.

Exceptions:

  1. Where other factored load combinations are specifically required by other provisions of this code, such combinations shall take precedence.
  2. Where the effect of H resists the primary variable load effect, a load factor of 0.9 shall be included with H where H is permanent and H shall be set to zero for all other conditions.
Where flood loads, Fa, are to be considered in the design, the load combinations of Section 2.3.3 of ASCE 7 shall be used. Where self-straining loads, T, are considered in design, their structural effects in combination with other loads shall be determined in accordance with Section 2.3.5 of ASCE 7. Where an ice-sensitive structure is subjected to loads due to atmospheric icing, the load combinations of Section 2.3.4 of ASCE 7 shall be considered.

Where allowable stress design (working stress design), as permitted by this code, is used, structures and portions thereof shall resist the most critical effects resulting from the following combinations of loads:

(Equation 16A-8)

(Equation 16A-9)

(Equation 16A-10)

(Equation 16A-11)

(Equation 16A-12)

(Equation 16A-13)

(Equation 16A-14)

(Equation 16A-15)

(Equation 16A-16)

Exceptions:

  1. Crane hook loads need not be combined with roof live load or with more than three-fourths of the snow load or one-half of the wind load.
  2. Flat roof snow loads of 30 psf (1.44 kN/m2) or less and roof live loads of 30 psf (1.44 kN/m2) or less need not be combined with seismic loads. Where flat roof snow loads exceed 30 psf (1.44 kN/m2), 20 percent shall be combined with seismic loads.
  3. Where the effect of H resists the primary variable load effect, a load factor of 0.6 shall be included with H where H is permanent and H shall be set to zero for all other conditions.
  4. In Equation 16A-15, the wind load, W, is permitted to be reduced in accordance with Exception 2 of Section 2.4.1 of ASCE 7.
  5. In Equation 16A-16, 0.6 D is permitted to be increased to 0.9 D for the design of special reinforced masonry shear walls complying with Chapter 21.
Increases in allowable stresses specified in the appropriate material chapter or the referenced standards shall not be used with the load combinations of Section 1605A.3.1, except that increases shall be permitted in accordance with Chapter 23.
Where flood loads, Fa, are to be considered in design, the load combinations of Section 2.4.2 of ASCE 7 shall be used. Where self-straining loads, T, are considered in design, their structural effects in combination with other loads shall be determined in accordance with Section 2.4.4 of ASCE 7. Where an ice-sensitive structure is subjected to loads due to atmospheric icing, the load combinations of Section 2.4.3 of ASCE 7 shall be considered.

In lieu of the basic load combinations specified in Section 1605A.3.1, structures and portions thereof shall be permitted to be designed for the most critical effects resulting from the following combinations. When using these alternative basic load combinations that include wind or seismic loads, allowable stresses are permitted to be increased or load combinations reduced where permitted by the material chapter of this code or the referenced standards. For load combinations that include the counteracting effects of dead and wind loads, only two-thirds of the minimum dead load likely to be in place during a design wind event shall be used. When using allowable stresses that have been increased or load combinations that have been reduced as permitted by the material chapter of this code or the referenced standards, where wind loads are calculated in accordance with Chapters 26 through 31 of ASCE 7, the coefficient (ω) in the following equations shall be taken as 1.3. For other wind loads, (ω) shall be taken as 1. When allowable stresses have not been increased or load combinations have not been reduced as permitted by the material chapter of this code or the referenced standards, (ω) shall be taken as 1. When using these alternative load combinations to evaluate sliding, overturning and soil bearing at the soil-structure interface, the reduction of foundation overturning from Section 12.13.4 in ASCE 7 shall not be used. When using these alternative basic load combinations for proportioning foundations for loadings, which include seismic loads, the vertical seismic load effect, Ev, in Equation 12.4-4 of ASCE 7 is permitted to be taken equal to zero.

(Equation 16A-17)

(Equation 16A-18)

(Equation 16A-19)

(Equation 16A-20)

(Equation 16A-21)

(Equation 16A-22)

Exceptions:

  1. Crane hook loads need not be combined with roof live loads or with more than three-fourths of the snow load or one-half of the wind load.
  2. Flat roof snow loads of 30 psf (1.44 kN/m2) or less and roof live loads of 30 psf (1.44 kN/m2) or less need not be combined with seismic loads. Where flat roof snow loads exceed 30 psf (1.44 kN/m2), 20 percent shall be combined with seismic loads.
Where F, H or T are to be considered in the design, each applicable load shall be added to the combinations specified in Section 1605A.3.2. Where self-straining loads, T, are considered in design, their structural effects in combination with other loads shall be determined in accordance with Section 2.4.4 of ASCE 7.
The text of ICC 300 shall be modified as indicated in Section 1605A.4.1 through 1605A.4.3.
Modify Section 303.5.1 by adding Equation 3-1a and replacing Equation 3-2 as follows:

0.9D + 0.4L + 1.6Z (Equation 3-1a)
1.2D + 1.6L + 1.6Rr (Equation 3-2)
Modify Section 303.5.2 by adding Equation 3-3a, adding Equation 3-3b, and replacing Equation 3-4 as follows:
D + 0.4L + Z (Equation 3-3a)
0.6D + 0.3L + Z (Equation 3-3b)
D + L + Rr (Equation 3-4)
Modify Section 303.5.3 as follows:

The uniform live load L used in Equation 3-2 and 3-4 may be taken as zero when evaluating elements supporting the handrail/guard provided those elements do not also support L.
Dead loads are those loads defined in Chapter 2 of this code. Dead loads shall be considered permanent loads.
For purposes of design, the actual weights of materials of construction and fixed service equipment shall be used. In the absence of definite information, values used shall be subject to the approval of the building official.

The design dead load shall provide for the weight of at least one additional roof covering in addition to other applicable loadings if the new roof covering is permitted to be applied over the original roofing without its removal, in accordance with Section 1511.

Live loads are those loads defined in Chapter 2 and Section 1602A.1 of this code.

TABLE 1607A.1

MINIMUM UNIFORMLY DISTRIBUTED LIVE LOADS, Lo, AND MINIMUM CONCENTRATED LIVE LOADSg

OCCUPANCY OR USEUNIFORM (psf)CONCENTRATED (lbs.)
1. Apartments (see residential)
2. Access floor systems
Office use502,000
Computer use1002,000
3. Armories and drill rooms150m
4. Assembly areas o, q
Fixed seats (fastened to floor)60 m
Follow spot, projections and control rooms50
Lobbies100 m
Movable seats100 m
Stage floors150 m
Platforms (assembly)100 m
Other assembly areas100 m
5. Balconies and decksh[DSA-SS] 1.5 times the live load for the area served. Not required to exceed 100 psf
6. Catwalks40300
7. Cornices60
8. Corridors
First floor100
Other floorsSame as occupancy served except as indicated
9. Dining rooms and restaurants100m
10. Dwellings (see residential)
11. Elevator machine room and control room grating (on area of 2 inches by 2 inches)300
12. Finish light floor plate construction (on area of 1 inch by 1 inch)200
13. Fire escapes100
On single-family dwellings only40
14. Garages (passenger vehicles only)40mNote a
Trucks and busesSee Section 1607.7
15. Handrails, guards and grab barsSee Section 1607.8
16. HelipadsSee Section 1607.6
17. Hospitals [OSHPD 1 & 4]
Corridors above first floor801,000
Operating rooms, laboratories601,000
Patient rooms401,000
Mechanical and electrical equipment areas including open areas around equipment50
Storage
Light125
Heavy250
Dining Area (not used for assembly)1001,000
Kitchen and serving areas501,000
18. Hotels (see residential)
19. Librariesn
Corridors above first floor801,000
Reading rooms60m1,000
Stack rooms150b, m1,000
20. Manufacturing
Heavy250m3,000
Light125m2,000
21. Marquees, except one- and two-family dwellings75
22. Office buildings n
Corridors above first floor802,000
File and computer rooms shall be designed for heavier loads based on anticipated occupancy
Lobbies and first-floor corridors1002,000
Offices502,000
23. Penal institutions
Cell blocks40
Corridors100
24. Recreational uses:
Bowling alleys, poolrooms and similar uses75m
Dance halls and ballrooms100m
Gymnasiums100m
Ice skating rink250m
Reviewing stands, grandstands and bleachersq100c, m
Roller skating rink100m
Stadiums and arenas with fixed seats (fastened to floor)60c, m
25. Residential
One- and two-family dwellings
Uninhabitable attics without storagei10
Uninhabitable attics with storagei, j, k20
Habitable attics and sleeping areask30
Canopies, including marquees20
All other areas40
Hotels and multifamily dwellings
Private rooms and corridors serving them40
Public roomsm and corridors serving them100
26. Roofs
All roof surfaces subject to maintenance workers300
Awnings and canopies:
Fabric construction supported by a skeleton structure5 Nonreducible
All other construction, except one- and two-family dwellings20
Ordinary flat, pitched, and curved roofs (that are not occupiable)20
Primary roof members exposed to a work floor
Single panel point of lower chord of roof trusses or any point along primary structural members supporting roofs over manufacturing, storage warehouses, and repair garages2,000
All other primary roof members300
Occupiable roofs:
Roof gardens100
Assembly areas 100m
All other similar areasNote 1Note 1
27. Schools n
Classrooms40 p1,000
Corridors above first floor801,000
First-floor corridors1001,000
28. Scuttles, skylight ribs and accessible ceilings200
29. Sidewalks, vehicular drive ways and yards, subject to trucking250d, m8,000e
30. Stairs and exits
One- and two-family dwellings40300 f
All other100300 f
31. Storage warehouses (shall be designed for heavier loads if required for anticipated storage)
Heavy250m
Light125m
32. Stores
Retail
First floor1001,000
Upper floors751,000
Wholesale, all floors125m1,000
33. Vehicle barriersSee Section 1607.8.3
34. Walkways and elevated platforms (other than exitways)60
35. Yards and terraces, pedestriansr100m
36. Storage racks and wall-hung cabinetsTotal loadsn

For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2,

1 square foot = 0.0929 m2,

1 pound per square foot = 0.0479 kN/m2, 1 pound = 0.004448 kN,

1 pound per cubic foot = 16 kg/m3.

  1. Floors in garages or portions of buildings used for the storage of motor vehicles shall be designed for the uniformly distributed live loads of this Table or the following concentrated loads: (1) for garages restricted to passenger vehicles accommodating not more than nine passengers, 3,000 pounds acting on an area of 41/2 inches by 41/2 inches; (2) for mechanical parking structures without slab or deck that are used for storing passenger vehicles only, 2,250 pounds per wheel.
  2. The loading applies to stack room floors that support nonmobile, double-faced library book stacks, subject to the following limitations:

    1. The nominal book stack unit height shall not exceed 90 inches;
    2. The nominal shelf depth shall not exceed 12 inches for each face; and
    3. Parallel rows of double-faced book stacks shall be separated by aisles not less than 36 inches wide.
  3. Design in accordance with ICC 300 [DSA-SS] as modified by Section 1605A.4 load combinations.
  4. Other uniform loads in accordance with an approved method containing provisions for truck loadings shall be considered where appropriate.
  5. The concentrated wheel load shall be applied on an area of 4.5 inches by 4.5 inches.
  6. The minimum concentrated load on stair treads shall be applied on an area of 2 inches by 2 inches. This load need not be assumed to act concurrently with the uniform load.
  7. Where snow loads occur that are in excess of the design conditions, the structure shall be designed to support the loads due to the increased loads caused by drift buildup or a greater snow design determined by the building official (see Section 1608).
  8. See Section 1604.8.3 for decks attached to exterior walls.
  9. Uninhabitable attics without storage are those where the maximum clear height between the joists and rafters is less than 42 inches, or where there are not two or more adjacent trusses with web configurations capable of accommodating an assumed rectangle 42 inches in height by 24 inches in width, or greater, within the plane of the trusses. This live load need not be assumed to act concurrently with any other live load requirements.
  10. Uninhabitable attics with storage are those where the maximum clear height between the joists and rafters is 42 inches or greater, or where there are two or more adjacent trusses with web configurations capable of accommodating an assumed rectangle 42 inches in height by 24 inches in width, or greater, within the plane of the trusses.

    The live load need only be applied to those portions of the joists or truss bottom chords where both of the following conditions are met:

    1. The attic area is accessible from an opening not less than 20 inches in width by 30 inches in length that is located where the clear height in the attic is a minimum of 30 inches; and
    2. The slopes of the joists or truss bottom chords are no greater than two units vertical in 12 units horizontal.

      The remaining portions of the joists or truss bottom chords shall be designed for a uniformly distributed concurrent live load of not less than 10 pounds per square foot.

  11. Attic spaces served by stairways other than the pull-down type shall be designed to support the minimum live load specified for habitable attics and sleeping rooms.
  12. Areas of occupiable roofs, other than roof gardens and assembly areas, shall be designed for appropriate loads as approved by the building official. Unoccupied landscaped areas of roofs shall be designed in accordance with Section 1607.12.3.
  13. Live load reduction is not permitted unless specific exceptions of Section 1607.10 apply.
  14. The minimum vertical design live load shall be as follows:

    Paper media:
    12-inch-deep shelf33 pounds per lineal foot
    15-inch-deep shelf41 pounds per lineal foot, or
    33 pounds per cubic foot per total volume of the rack or cabinet, whichever is less.
    Film media:
    18-inch-deep shelf100 pounds per lineal foot, or
    50 pounds per cubic foot per total volume of the rack or cabinet, whichever is less.
    Other media:
    20 pounds per cubic foot or 20 pounds per square foot, whichever is less, but not less than actual loads.
  15. [DSA-SS] The following minimum loads for stage accessories apply:

    1. Gridirons and fly galleries: 75 pounds per square foot uniform live load.
    2. Loft block wells: 250 pounds per lineal foot vertical load and lateral load.
    3. Head block wells and sheave beams: 250 pounds per lineal foot vertical load and lateral load. Head block wells and sheave beams shall be designed for all tributary loft block well loads. Sheave blocks shall be designed with a safety factor of five.
    4. Scenery beams where there is no gridiron: 300 pounds per lineal foot vertical load and lateral load.
    5. Ceiling framing over stages shall be designed for a uniform live load of 20 pounds per square foot. For members supporting a tributary area of 200 square feet or more, this additional load may be reduced to 15 pounds per square foot.
  16. [DSA-SS] The minimum uniform live load for classroom occupancies is 50 psf. Live load reduction is not permitted for classrooms classified as Group A occupancies unless specific exception of Section 1607A.10 apply.
  17. [DSA-SS] The minimum uniform live load for a press box floor or accessible roof with railing is 100 psf.
  18. [DSA-SS] Item 35 applies to pedestrian bridges and walkways that are not subjected to uncontrolled vehicle access.
For occupancies or uses not designated in Table 1607A.1, the live load shall be determined in accordance with a method approved by the building official.
The live loads used in the design of buildings and other structures shall be the maximum loads expected by the intended use or occupancy but shall in no case be less than the minimum uniformly distributed live loads given in Table 1607A.1.
Floors and other similar surfaces shall be designed to support the uniformly distributed live loads prescribed in Section 1607A.3 or the concentrated live loads, given in Table 1607A.1, whichever produces the greater load effects. Unless otherwise specified, the indicated concentration shall be assumed to be uniformly distributed over an area of 21/2 feet by 21/2 feet (762 mm by 762 mm) and shall be located so as to produce the maximum load effects in the structural members.
In office buildings and in other buildings where partition locations are subject to change, provisions for partition weight shall be made, whether or not partitions are shown on the construction documents, unless the specified live load is 80 psf (3.83 kN/m2) or greater. The partition load shall be not less than a uniformly distributed live load of 15 psf (0.72 kN/m2).

Helipads shall be designed for the following live loads:

  1. A uniform live load, L, as specified below. This load shall not be reduced.

    1. 1.1. 40 psf (1.92 kN/m2) where the design basis helicopter has a maximum take-off weight of 3,000 pounds (13.35 kN) or less.
    2. 1.2. 60 psf (2.87 kN/m2) where the design basis helicopter has a maximum take-off weight greater than 3,000 pounds (13.35 kN).
  2. A single concentrated live load, L, of 3,000 pounds (13.35 kN) applied over an area of 4.5 inches by 4.5 inches (114 mm by 114 mm) and located so as to produce the maximum load effects on the structural elements under consideration. The concentrated load is not required to act concurrently with other uniform or concentrated live loads.
  3. Two single concentrated live loads, L, 8 feet (2438 mm) apart applied on the landing pad (representing the helicopter’s two main landing gear, whether skid type or wheeled type), each having a magnitude of 0.75 times the maximum take-off weight of the helicopter, and located so as to produce the maximum load effects on the structural elements under consideration. The concentrated loads shall be applied over an area of 8 inches by 8 inches (203 mm by 203 mm) and are not required to act concurrently with other uniform or concentrated live loads.

Landing areas designed for a design basis helicopter with maximum take-off weight of 3,000-pounds (13.35 kN) shall be identified with a 3,000 pound (13.34 kN) weight limitation. The landing area weight limitation shall be indicated by the numeral “3” (kips) located in the bottom right corner of the landing area as viewed from the primary approach path. The indication for the landing area weight limitation shall be a minimum 5 feet (1524 mm) in height.

Floors and other surfaces that are intended to support vehicle loads greater than a 10,000-pound (4536 kg) gross vehicle weight rating shall comply with Sections 1607A.7.1 through 1607A.7.5.
Where any structure does not restrict access for vehicles that exceed a 10,000-pound (4536 kg) gross vehicle weight rating, those portions of the structure subject to such loads shall be designed using the vehicular live loads, including consideration of impact and fatigue, in accordance with the codes and specifications required by the jurisdiction having authority for the design and construction of the roadways and bridges in the same location of the structure.

Where a structure or portions of a structure are accessed and loaded by fire department access vehicles and other similar emergency vehicles, the structure shall be designed for the greater of the following loads:

  1. The actual operational loads, including outrigger reactions and contact areas of the vehicles as stipulated and approved by the building official; or
  2. The live loading specified in Section 1607A.7.1.

Garages designed to accommodate vehicles that exceed a 10,000-pound (4536 kg) gross vehicle weight rating, shall be designed using the live loading specified by Section 1607A.7.1. For garages the design for impact and fatigue is not required.

Exception: The vehicular live loads and load placement are allowed to be determined using the actual vehicle weights for the vehicles allowed onto the garage floors, provided such loads and placement are based on rational engineering principles and are approved by the building official, but shall not be less than 50 psf (2.9 kN/m2). This live load shall not be reduced.

Where a structure is intended to have forklifts or other movable equipment present, the structure shall be designed for the total vehicle or equipment load and the individual wheel loads for the anticipated vehicles as specified by the owner of the facility. These loads shall be posted in accordance with Section 1607A.7.5.
Impact loads and fatigue loading shall be considered in the design of the supporting structure. For the purposes of design, the vehicle and wheel loads shall be increased by 30 percent to account for impact.
The maximum weight of vehicles allowed into or on a garage or other structure shall be posted by the owner or the owner’s authorized agent in accordance with Section 106.1.
Handrails, guards, grab bars, accessible seats, accessible benches and vehicle barriers shall be designed and constructed for the structural loading conditions set forth in this section.

Handrails and guards shall be designed to resist a linear load of 50 pounds per linear foot (plf) (0.73 kN/m) in accordance with Section 4.5.1 of ASCE 7. Glass handrail assemblies and guards shall also comply with Section 2407.

Exceptions:

  1. For one- and two-family dwellings, only the single concentrated load required by Section 1607A.8.1.1 shall be applied.
  2. In Group I-3, F, H and S occupancies, for areas that are not accessible to the general public and that have an occupant load less than 50, the minimum load shall be 20 pounds per foot (0.29 kN/m).
Handrails and guards shall be designed to resist a concentrated load of 200 pounds (0.89 kN) in accordance with Section 4.5.1 of ASCE 7.
Intermediate rails (all those except the handrail), balusters and panel fillers shall be designed to resist a concentrated load of 50 pounds (0.22 kN) in accordance with Section 4.5.1 of ASCE 7.
Grab bars, shower seats and dressing room bench seats shall be designed to resist a single concentrated load of 250 pounds (1.11 kN) applied in any direction at any point on the grab bar or seat so as to produce the maximum load effects. [DSA-AC] See Chapter 11A, Section 1127A.4, and Chapter 11B, Sections 11B-609.8, 11B-610.4 and 11B-903.6 for grab bars, shower seats and dressing room bench seats, as applicable.
Vehicle barriers for passenger vehicles shall be designed to resist a concentrated load of 6,000 pounds (26.70 kN) in accordance with Section 4.5.3 of ASCE 7. Garages accommodating trucks and buses shall be designed in accordance with an approved method that contains provisions for traffic railings.
The live loads specified in Sections 1607A.3 through 1607A.8 shall be assumed to include adequate allowance for ordinary impact conditions. Provisions shall be made in the structural design for uses and loads that involve unusual vibration and impact forces.
Members, elements and components subject to dynamic loads from elevators shall be designed for impact loads and deflection limits prescribed by ASME A17.1.
For the purpose of design, the weight of machinery and moving loads shall be increased as follows to allow for impact: (1) light machinery, shaft-or motor-driven, 20 percent; and (2) reciprocating machinery or power-driven units, 50 percent. Percentages shall be increased where specified by the manufacturer.
In addition to any other applicable live loads, structural elements that support hoists for façade access equipment shall be designed for a live load consisting of the larger of the rated load of the hoist times 2.5 and the stall load of the hoist.

In addition to any other applicable live loads, lifeline anchorages and structural elements that support lifeline anchorages shall be designed for a live load of at least 3,100 pounds (13.8 kN) for each attached lifeline, in every direction that a fall arrest load may be applied.

Except for uniform live loads at roofs, all other minimum uniformly distributed live loads, Lo, in Table 1607A.1 are permitted to be reduced in accordance with Section 1607A.10.1 or 1607A.10.2. Uniform live loads at roofs are permitted to be reduced in accordance with Section 1607A.12.2.

Subject to the limitations of Sections 1607A.10.1.1 through 1607A.10.1.3 and Table 1607A.1, members for which a value of KLLAT is 400 square feet (37.16 m2) or more are permitted to be designed for a reduced uniformly distributed live load, L, in accordance with the following equation:

(Equation 16A-23)

For SI:

where:

L=Reduced design live load per square foot (m2) of area supported by the member.
Lo=Unreduced design live load per square foot (m2) of area supported by the member (see Table 1607A.1).
KLL=Live load element factor (see Table 1607A.10.1).
AT=Tributary area, in square feet (m2).

L shall be not less than 0.50Lo for members supporting one floor and L shall be not less than 0.40Lo for members supporting two or more floors.

TABLE 1607A.10.1

LIVE LOAD ELEMENT FACTOR, KLL

ELEMENTKLL
Interior columns4
Exterior columns without cantilever slabs4
Edge columns with cantilever slabs3
Corner columns with cantilever slabs2
Edge beams without cantilever slabs2
Interior beams2
All other members not identified above including:
Edge beams with cantilever slabs
Cantilever beams
One-way slabs1
Two-way slabs
Members without provisions for continuous shear transfer normal to their span
The tributary area, AT, for use in Equation 16A-23 for one-way slabs shall not exceed an area defined by the slab span times a width normal to the span of 1.5 times the slab span.

Live loads that exceed 100 psf (4.79 kN/m2) shall not be reduced.

Exceptions:

  1. The live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent, but the live load shall be not less than L as calculated in Section 1607A.10.1.
  2. For uses other than storage, where approved, additional live load reductions shall be permitted where shown by the registered design professional that a rational approach has been used and that such reductions are warranted.

The live loads shall not be reduced in passenger vehicle garages.

Exception: The live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent, but the live load shall not be less than L as calculated in Section 1607A.10.1.

As an alternative to Section 1607A.10.1 and subject to the limitations of Table 1607A.1, uniformly distributed live loads are permitted to be reduced in accordance with the following provisions. Such reductions shall apply to slab systems, beams, girders, columns, piers, walls and foundations.

  1. A reduction shall not be permitted where the live load exceeds 100 psf (4.79 kN/m2) except that the design live load for members supporting two or more floors is permitted to be reduced by a maximum of 20 percent.

    Exception: For uses other than storage, where approved, additional live load reductions shall be permitted where shown by the registered design professional that a rational approach has been used and that such reductions are warranted.

  2. A reduction shall not be permitted in passenger vehicle parking garages except that the live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent.
  3. For live loads not exceeding 100 psf (4.79 kN/m2), the design live load for any structural member supporting 150 square feet (13.94 m2) or more is permitted to be reduced in accordance with Equation 16A-24.
  4. For one-way slabs, the area, A, for use in Equation 16A-24 shall not exceed the product of the slab span and a width normal to the span of 0.5 times the slab span.

(Equation 16A–24)

For SI: R = 0.861(A – 13.94)

Such reduction shall not exceed the smallest of:

  1. 40 percent for members supporting one floor.
  2. 60 percent for members supporting two or more floors.
  3. R as determined by the following equation:

(Equation 16A-25)

where:

A = Area of floor supported by the member, square feet (m2).

D = Dead load per square foot (m2) of area supported.

Lo = Unreduced live load per square foot (m2) of area supported.

R = Reduction in percent.

Where uniform floor live loads are involved in the design of structural members arranged so as to create continuity, the minimum applied loads shall be the full dead loads on all spans in combination with the floor live loads on spans selected to produce the greatest load effect at each location under consideration. Floor live loads are permitted to be reduced in accordance with Section 1607A.10.
The structural supports of roofs and marquees shall be designed to resist wind and, where applicable, snow and earthquake loads, in addition to the dead load of construction and the appropriate live loads as prescribed in this section, or as set forth in Table 1607A.1. The live loads acting on a sloping surface shall be assumed to act vertically on the horizontal projection of that surface.
Where uniform roof live loads are reduced to less than 20 psf (0.96 kN/m2) in accordance with Section 1607A.12.2.1 and are applied to the design of structural members arranged so as to create continuity, the reduced roof live load shall be applied to adjacent spans or to alternate spans, whichever produces the most unfavorable load effect. See Section 1607A.12.2 for reductions in minimum roof live loads and Section 7.5 of ASCE 7 for partial snow loading.
The minimum uniformly distributed live loads of roofs and marquees, Lo, in Table 1607.1 are permitted to be reduced in accordance with Section 1607A.12.2.1.

Ordinary flat, pitched and curved roofs, and awnings and canopies other than of fabric construction supported by a skeleton structure, are permitted to be designed for a reduced uniformly distributed roof live load, Lr, as specified in the following equations or other controlling combinations of loads as specified in Section 1605A, whichever produces the greater load effect.

In structures such as greenhouses, where special scaffolding is used as a work surface for workers and materials during maintenance and repair operations, a lower roof load than specified in the following equations shall not be used unless approved by the building official. Such structures shall be designed for a minimum roof live load of 12 psf (0.58 kN/m2).

(Equation 16A-26)

where: 12 ≤ Lr ≤ 20

For SI: Lr = Lo R1 R2

where: 0.58 ≤ Lr ≤ 0.96

Lo = Unreduced roof live load per square foot (m2) of horizontal projection supported by the member (see Table 1607A.1).

Lr = Reduced roof live load per square foot (m2) of horizontal projection supported by the member.

The reduction factors R1 and R2 shall be determined as follows:

(Equation 16A-27)

(Equation 16A-28)

For SI: 1.2 – 0.011At for 18.58 square meters < At < 55.74 square meters

(Equation 16A-29)

where:

At = Tributary area (span length multiplied by effective width) in square feet (m2) supported by the member, and

(Equation 16A-30)

(Equation 16A-31)

(Equation 16A-32)

where:

F = For a sloped roof, the number of inches of rise per foot (for SI: F = 0.12 × slope, with slope expressed as a percentage), or for an arch or dome, the rise-to-span ratio multiplied by 32.

Areas of roofs that are occupiable, such as vegetative roofs, roof gardens or for assembly or other similar purposes, and marquees are permitted to have their uniformly distributed live loads reduced in accordance with Section 1607A.10.
The weight of all landscaping materials shall be considered as dead load and shall be computed on the basis of saturation of the soil as determined in accordance with ASTM E2397. The uniform design live load in unoccupied landscaped areas on roofs shall be 20 psf (0.958 kN/m2). The uniform design live load for occupied landscaped areas on roofs shall be determined in accordance with Table 1607A.1.
Awnings and canopies shall be designed for uniform live loads as required in Table 1607A.1 as well as for snow loads and wind loads as specified in Sections 1608A and 1609A.
Roof structures that provide support for photovoltaic panel systems shall be designed in accordance with Sections 1607A.12.5.1 through 1607A.12.5.4, as applicable.
Roof surfaces to be covered by solar photovoltaic panels or modules shall be designed for the roof live load, Lr, assuming that the photovoltaic panels or modules are not present. The roof photovoltaic live load in areas covered by solar photo-voltaic panels or modules shall be in addition to the panel loading unless the area covered by each solar photovoltaic panel or module is inaccessible. Areas where the clear space between the panels and the rooftop is not more than 24 inches (610 mm) shall be considered inac cessible. Roof surfaces not covered by photovoltaic panels shall be designed for the roof live load.
The structure of a roof that supports solar photovoltaic panels or modules shall be designed to accommodate the full solar photovoltaic panels or modules and ballast dead load, including concentrated loads from support frames in combination with the loads from Section 1607A.12.5.1 and other applicable loads. Where applicable, snow drift loads created by the photovoltaic panels or modules shall be included.

Solar photovoltaic panels or modules that are independent structures and do not have accessible/occupied space underneath are not required to accommodate a roof photovoltaic live load, provided the area under the structure is restricted to keep the public away. All other loads and combinations in accordance with Section 1605A shall be accommodated.

Solar photovoltaic panels or modules that are designed to be the roof, span to structural supports and have accessible/occupied space underneath shall have the panels or modules and all supporting structures designed to support a roof photovoltaic live load, as defined in Section 1607A.12.5.1 in combination with other applicable loads. Solar photovoltaic panels or modules in this application are not permitted to be classified as “not accessible” in accordance with Section 1607A.12.5.1.

Roof structures that provide support for ballasted photovoltaic panel systems shall be designed, or analyzed, in accordance with Section 1604A.4; checked in accordance with Section 1604A.3.6 for deflections; and checked in accordance with Section 1611A for ponding.

Uncovered open-frame roof structures shall be designed for a vertical live load of not less than 10 pounds per square foot (0.48 kN/m2) of the total area encompassed by the framework.

The crane live load shall be the rated capacity of the crane. Design loads for the runway beams, including connections and support brackets, of moving bridge cranes and monorail cranes shall include the maximum wheel loads of the crane and the vertical impact, lateral and longitudinal forces induced by the moving crane.
The maximum wheel loads shall be the wheel loads produced by the weight of the bridge, as applicable, plus the sum of the rated capacity and the weight of the trolley with the trolley positioned on its runway at the location where the resulting load effect is maximum.

The maximum wheel loads of the crane shall be increased by the percentages shown below to determine the induced vertical impact or vibration force:

Monorail cranes (powered)25 percent
Cab-operated or remotely operated bridge cranes (powered)25 percent
Pendant-operated bridge cranes (powered)10 percent
Bridge cranes or monorail cranes with hand-geared bridge, trolley and hoist0 percent
The lateral force on crane runway beams with electrically powered trolleys shall be calculated as 20 percent of the sum of the rated capacity of the crane and the weight of the hoist and trolley. The lateral force shall be assumed to act horizontally at the traction surface of a runway beam, in either direction perpendicular to the beam, and shall be distributed with due regard to the lateral stiffness of the runway beam and supporting structure.
The longitudinal force on crane runway beams, except for bridge cranes with hand-geared bridges, shall be calculated as 10 percent of the maximum wheel loads of the crane. The longitudinal force shall be assumed to act horizontally at the traction surface of a runway beam, in either direction parallel to the beam.
Interior walls and partitions that exceed 6 feet (1829 mm) in height, including their finish materials, shall have adequate strength and stiffness to resist the loads to which they are subjected but not less than a horizontal load of 5 psf (0.240 kN/m2). The 5 psf (0.24 kN/m2) service load need not be applied simultaneously with wind or seismic loads. The deflection of such walls under a load of 5 psf (0.24 kN/m2)shall not exceed the limits in Table 1604A.3.

Fabric partitions that exceed 6 feet (1829 mm) in height, including their finish materials, shall have adequate strength and stiffness to resist the following load conditions:

  1. The horizontal distributed load need only be applied to the partition framing. The total area used to determine the distributed load shall be the area of the fabric face between the framing members to which the fabric is attached. The total distributed load shall be uniformly applied to such framing members in proportion to the length of each member.
  2. A concentrated load of 40 pounds (0.176 kN) applied to an 8-inch-diameter (203 mm) area [50.3 square inches (32 452 mm2)] of the fabric face at a height of 54 inches (1372 mm) above the floor.
Design snow loads shall be determined in accordance with Chapter 7 of ASCE 7, but t he design roof load shall not be less than that determined by Section 1607A.

The ground snow loads to be used in determining the design snow loads for roofs shall be determined in accordance with ASCE 7 or Figure 1608A.2 for the contiguous United States. Site-specific case studies shall be made in areas designated “CS” in Figure 1608A.2. Ground snow loads for sites at elevations above the limits indicated in Figure 1608A.2 and for all sites within the CS areas shall be approved. Ground snow load determination for such sites shall be based on an extreme value statistical analysis of data available in the vicinity of the site using a value with a 2-percent annual probability of being exceeded (50-year mean recurrence interval).

FIGURE 1608A.2

GROUND SNOW LOADS, pg, FOR THE UNITED STATES (psf)

FIGURE 1608A.2

GROUND SNOW LOADS, pg, FOR THE UNITED STATES (psf)

Susceptible bays of roofs shall be evaluated for ponding instability in accordance with Section 7.11 of ASCE 7.

[DSA-SS] The ground snow load or the design snow load for roofs shall conform with the adopted ordinance of the city, county, or city and county in which the project site is located, and shall be approved by DSA.

Buildings, structures and parts thereof shall be designed to withstand the minimum wind loads prescribed herein. Decreases in wind loads shall not be made for the effect of shielding by other structures.

Wind loads on every building or structure shall be determined in accordance with Chapters 26 to 30 of ASCE 7 or provisions of the alternate all-heights method in Section 1609A.6. The type of opening protection required, the ultimate design wind speed, Vult, and the exposure category for a site is permitted to be determined in accordance with Section 1609A or ASCE 7. Wind shall be assumed to come from any horizontal direction and wind pressures shall be assumed to act normal to the surface considered.

Exceptions:

  1. Subject to the limitations of Section 1609A.1.1.1, the provisions of ICC 600 shall be permitted for applicable Group R-2 and R-3 buildings.
  2. Subject to the limitations of Section 1609A.1.1.1, residential structures using the provisions of AWC WFCM.
  3. Subject to the limitations of Section 1609A.1.1.1, residential structures using the provisions of AISI S230.
  4. Designs using NAAMM FP 1001.
  5. Designs using TIA-222 for antenna-supporting structures and antennas, provided the horizontal extent of Topographic Category 2 escarpments in Section 2.6.6.2 of TIA-222 shall be 16 times the height of the escarpment.
  6. Wind tunnel tests in accordance with ASCE 49 and Sections 31.4 and 31.5 of ASCE 7.

The wind speeds in Figures 1609A.3(1), 1609A.3(2) and 1609A.3(3) are ultimate design wind speeds, Vult, and shall be converted in accordance with Section 1609A.3.1 to nominal design wind speeds, Vasd, when the provisions of the standards referenced in Exceptions 4 and 5 are used.

The provisions of ICC 600 are applicable only to buildings located within Exposure B or C as defined in Section 1609A.4. The provisions of ICC 600, AWC WFCM and AISI S230 shall not apply to buildings sited on the upper half of an isolated hill, ridge or escarpment meeting the following conditions:

  1. The hill, ridge or escarpment is 60 feet (18 288 mm) or higher if located in Exposure B or 30 feet (9144 mm) or higher if located in Exposure C;
  2. The maximum average slope of the hill exceeds 10 percent; and
  3. The hill, ridge or escarpment is unobstructed upwind by other such topographic features for a distance from the high point of 50 times the height of the hill or 1 mile (1.61 km), whichever is greater.

In wind-borne debris regions, glazing in buildings shall be impact resistant or protected with an impact-resistant covering meeting the requirements of an approved impact-resistant standard or ASTM E1996 and ASTM E1886 referenced herein as follows:

  1. Glazed openings located within 30 feet (9144 mm) of grade shall meet the requirements of the large missile test of ASTM E1996.
  2. Glazed openings located more than 30 feet (9144 mm) above grade shall meet the provisions of the small missile test of ASTM E1996.

Exceptions:

  1. Wood structural panels with a minimum thickness of 7/16 inch (11.1 mm) and maximum panel span of 8 feet (2438 mm) shall be permitted for opening protection in buildings with a mean roof height of 33 feet (10 058 mm) or less that are classified as a Group R-3 or R-4 occupancy. Panels shall be precut so that they shall be attached to the framing surrounding the opening containing the product with the glazed opening. Panels shall be predrilled as required for the anchorage method and shall be secured with the attachment hardware provided. Attachments shall be designed to resist the components and cladding loads determined in accordance with the provisions of ASCE 7, with corrosion-resistant attachment hardware provided and anchors permanently installed on the building. Attachment in accordance with Table 1609A.1.2 with corrosion-resistant attachment hardware provided and anchors permanently installed on the building is permitted for buildings with a mean roof height of 45 feet (13 716 mm) or less where Vasd determined in accordance with Section 1609A.3.1 does not exceed 140 mph (63 m/s).
  2. Glazing in Risk Category I buildings, including greenhouses that are occupied for growing plants on a production or research basis, without public access shall be permitted to be unprotected.
  3. Glazing in Risk Category II, III or IV buildings located over 60 feet (18 288 mm) above the ground and over 30 feet (9144 mm) above aggregate surface roofs located within 1,500 feet (458 m) of the building shall be permitted to be unprotected.

TABLE 1609A.1.2

WIND-BORNE DEBRIS PROTECTION FASTENING SCHEDULE FOR WOOD STRUCTURAL PANELSa, b, c, d

FASTENER TYPEFASTENER SPACING (inches)
Panel
Span
≤ 4 feet
4 feet < Panel
Span ≤ 6 feet
6 feet < Panel
Span ≤ 8 feet
No. 8 wood-screw-based
anchor with 2-inch
embedment length
16108
No. 10 wood-screw-based
anchor with 2-inch
embedment length
16129
1/4-inch diameter lag-
screw-based anchor with
2-inch embedment length
161616

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 4.448 N,

1 mile per hour = 0.447 m/s.

  1. This table is based on 140 mph wind speeds and a 45-foot mean roof height.
  2. Fasteners shall be installed at opposing ends of the wood structural panel. Fasteners shall be located a minimum of 1 inch from the edge of the panel.
  3. Anchors shall penetrate through the exterior wall covering with an embedment length of 2 inches minimum into the building frame. Fasteners shall be located a minimum of 21/2 inches from the edge of concrete block or concrete.
  4. Where panels are attached to masonry or masonry/stucco, they shall be attached using vibration-resistant anchors having a minimum ultimate withdrawal capacity of 1,500 pounds.
Louvers protecting intake and exhaust ventilation ducts not assumed to be open that are located within 30 feet (9144 mm) of grade shall meet the requirements of AMCA 54.

The text of Section 6.2.2 of ASTM E1996 shall be substituted as follows:

6.2.2 Unless otherwise specified, select the wind zone based on the strength design wind speed, Vult, as follows:

6.2.2.1 Wind Zone 1130 mph ≤ ultimate design wind speed, Vult < 140 mph.

6.2.2.2 Wind Zone 2140 mph ≤ ultimate design wind speed, Vult < 150 mph at greater than one mile (1.6 km) from the coastline. The coastline shall be measured from the mean high water mark.

6.2.2.3 Wind Zone 3—150 mph (58 m/s) ≤ ultimate design wind speed, Vult ≤ 160 mph (63 m/s), or 140 mph (54 m/s) ≤ ultimate design wind speed, Vult ≤ 160 mph (63 m/s) and within one mile (1.6 km) of the coastline. The coastline shall be measured from the mean high water mark.

6.2.2.4 Wind Zone 4— ultimate design wind speed, Vult >160 mph (63 m/s).

Garage door glazed opening protection for wind-borne debris shall meet the requirements of an approved impact-resisting standard or ANSI/DASMA 115.

The calculated story drift due to wind pressures with ultimate design wind speed, Vult , shall not exceed 0.008 times the story height for buildings less than 65 feet (19 812 mm) in height or 0.007 times the story height for buildings 65 feet (19 812 mm) or greater in height.

Exception: [DSA-SS] This story drift limit need not be applied for single-story open buildings in Risk Category I and II.

Exception: [OSHPD 1 & 4] This story drift limit need not be applied for single-story open structures.

For the purposes of Section 1609 and as used elsewhere in this code, the following terms are defined in Chapter 2.

HURRICANE-PRONE REGIONS.

WIND-BORNE DEBRIS REGION.

WIND SPEED, Vult .

WIND SPEED, Vasd .

The ultimate design wind speed, Vult, in mph, for the determination of the wind loads shall be determined by Figures 1609A.3(1), 1609A.3(2) and 1609A.3(3). The ultimate design wind speed, Vult, for use in the design of Risk Category II buildings and structures shall be obtained from Figure 1609A.3(1). The ultimate design wind speed, Vult, for use in the design of Risk Category III and IV buildings and structures shall be obtained from Figure 1609A.3(2). The ultimate design wind speed, Vult, for use in the design of Risk Category I buildings and structures shall be obtained from Figure 1609A.3(3). The ultimate design wind speed, Vult, for the special wind regions indicated near mountainous terrain and near gorges shall be in accordance with local jurisdiction requirements. The ultimate design wind speeds, Vult, determined by the local jurisdiction shall be in accordance with Section 26.5.1 of ASCE 7.

In nonhurricane-prone regions, when the ultimate design wind speed, Vult, is estimated from regional climatic data, the ultimate design wind speed, Vult, shall be determined in accordance with Section 26.5.3 of ASCE 7.

Notes:

  1. Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
  2. Linear interpolation between contours is permitted.
  3. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
  4. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
  5. Wind speeds correspond to approximately a 7% probability of exceedance in 50 years (Annual Exceedance Probability = 0.00143, MRI = 700 Years).

FIGURE 1609A.3(1)

ULTIMATE DESIGN WIND SPEEDS, VULT, FOR RISK CATEGORY II BUILDINGS AND OTHER STRUCTURES

Notes:

  1. Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
  2. Linear interpolation between contours is permitted.
  3. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
  4. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
  5. Wind speeds correspond to approximately a 3% probability of exceedance in 50 years (Annual Exceedance Probability = 0.000588, MRI = 1700 Years).

FIGURE 1609A.3(2)

ULTIMATE DESIGN WIND SPEEDS, VULT, FOR RISK CATEGORY III AND IV BUILDINGS AND OTHER STRUCTURES

Notes:

  1. Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
  2. Linear interpolation between contours is permitted.
  3. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
  4. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
  5. Wind speeds correspond to approximately a 15% probability of exceedance in 50 years (Annual Exceedance Probability = 0.00333, MRI = 300 Years).

FIGURE 1609A.3(3)

ULTIMATE DESIGN WIND SPEEDS, VULT, FOR RISK CATEGORY I BUILDINGS AND OTHER STRUCTURES

When required, the ultimate design wind speeds of Figures 1609A.3(1), 1609A.3(2) and 1609A.3(3) shall be converted to nominal design wind speeds, Vasd, using Table 1609A.3.1 or Equation 16A-33.

(Equation 16A-33)

where:

Vasd = nominal design wind speed applicable to methods specified in Exceptions 1 through 5 of Section 1609A.1.1.

Vult = ultimate design wind speeds determined from Figure 1609A, 1609B or 1609C.

TABLE 1609A.3.1

WIND SPEED CONVERSIONSa, b, c

Vult100110120130140150160170180190200
Vasd788593101108116124132139147155

For SI: 1 mile per hour = 0.44 m/s.

  1. Linear interpolation is permitted.
  2. Vasd = nominal design wind speed applicable to methods specified in Exceptions 1 through 5 of Section 1609A.1.1.
  3. Vult = ultimate design wind speeds determined from Figure 1609A.3(1), 1609A.3(2) or 1609A.3(3).
For each wind direction considered, an exposure category that adequately reflects the characteristics of ground surface irregularities shall be determined for the site at which the building or structure is to be constructed. Account shall be taken of variations in ground surface roughness that arise from natural topography and vegetation as well as from constructed features.
For each selected wind direction at which the wind loads are to be evaluated, the exposure of the building or structure shall be determined for the two upwind sectors extending 45 degrees (0.79 rad) either side of the selected wind direction. The exposures in these two sectors shall be determined in accordance with Sections 1609A.4.2 and 1609A.4.3 and the exposure resulting in the highest wind loads shall be used to represent winds from that direction.

A ground surface roughness within each 45-degree (0.79 rad) sector shall be determined for a distance upwind of the site as defined in Section 1609A.4.3 from the categories defined below, for the purpose of assigning an exposure category as defined in Section 1609A.4.3.

Surface Roughness B. Urban and suburban areas, wooded areas or other terrain with numerous closely spaced obstructions having the size of single-family dwellings or larger.

Surface Roughness C. Open terrain with scattered obstructions having heights generally less than 30 feet (9144 mm). This category includes flat open country, and grasslands.

Surface Roughness D. Flat, unobstructed areas and water surfaces. This category includes smooth mud flats, salt flats and unbroken ice.

An exposure category shall be determined in accordance with the following:

Exposure B. For buildings with a mean roof height of less than or equal to 30 feet (9144 mm), Exposure B shall apply where the ground surface roughness, as defined by Surface Roughness B, prevails in the upwind direction for a distance of at least 1,500 feet (457 m). For buildings with a mean roof height greater than 30 feet (9144 mm), Exposure B shall apply where Surface Roughness B prevails in the upwind direction for a distance of at least 2,600 feet (792 m) or 20 times the height of the building, whichever is greater.

Exposure C. Exposure C shall apply for all cases where Exposure B or D does not apply.

Exposure D. Exposure D shall apply where the ground surface roughness, as defined by Surface Roughness D, prevails in the upwind direction for a distance of at least 5,000 feet (1524 m) or 20 times the height of the building, whichever is greater. Exposure D shall also apply where the ground surface roughness immediately upwind of the site is B or C, and the site is within a distance of 600 feet (183 m) or 20 times the building height, whichever is greater, from an Exposure D condition as defined in the previous sentence.

Roof systems shall be designed and constructed in accordance with Sections 1609A.5.1 through 1609A.5.3, as applicable.
The roof deck shall be designed to withstand the wind pressures determined in accordance with ASCE 7.

Roof coverings shall comply with Section 1609A.5.1.

Exception: Rigid tile roof coverings that are air permeable and installed over a roof deck complying with Section 1609A.5.1 are permitted to be designed in accordance with Section 1609A.5.3.

Asphalt shingles installed over a roof deck complying with Section 1609A.5.1 shall comply with the wind-resistance requirements of Section 1504.1.1.

Wind loads on rigid tile roof coverings shall be determined in accordance with the following equation:

(Equation 16A-34)

For SI:

where:

b=Exposed width, feet (mm) of the roof tile.
CL=Lift coefficient. The lift coefficient for concrete and clay tile shall be 0.2 or shall be determined by test in accordance with Section 1504.2.1.
GCp=Roof pressure coefficient for each applicable roof zone determined from Chapter 30 of ASCE 7. Roof coefficients shall not be adjusted for internal pressure.
L=Length, feet (mm) of the roof tile.
La=Moment arm, feet (mm) from the axis of rotation to the point of uplift on the roof tile. The point of uplift shall be taken at 0.76L from the head of the tile and the middle of the exposed width. For roof tiles with nails or screws (with or without a tail clip), the axis of rotation shall be taken as the head of the tile for direct deck application or as the top edge of the batten for battened applications. For roof tiles fastened only by a nail or screw along the side of the tile, the axis of rotation shall be determined by testing. For roof tiles installed with battens and fastened only by a clip near the tail of the tile, the moment arm shall be determined about the top edge of the batten with consideration given for the point of rotation of the tiles based on straight bond or broken bond and the tile profile.
Ma=Aerodynamic uplift moment, feet-pounds (N-mm) acting to raise the tail of the tile.
qh=Wind velocity pressure, psf (kN/m2) determined from Section 27.3.2 of ASCE 7.

Concrete and clay roof tiles complying with the following limitations shall be designed to withstand the aerodynamic uplift moment as determined by this section.

  1. The roof tiles shall be either loose laid on battens, mechanically fastened, mortar set or adhesive set.
  2. The roof tiles shall be installed on solid sheathing that has been designed as components and cladding.
  3. An underlayment shall be installed in accordance with Chapter 15.
  4. The tile shall be single lapped interlocking with a minimum head lap of not less than 2 inches (51 mm).
  5. The length of the tile shall be between 1.0 and 1.75 feet (305 mm and 533 mm).
  6. The exposed width of the tile shall be between 0.67 and 1.25 feet (204 mm and 381 mm).
  7. The maximum thickness of the tail of the tile shall not exceed 1.3 inches (33 mm).
  8. Roof tiles using mortar set or adhesive set systems shall have at least two-thirds of the tile’s area free of mortar or adhesive contact.
The alternate wind design provisions in this section are simplifications of the ASCE 7 Directional Procedure.

As an alternative to ASCE 7 Chapters 27 and 30, the following provisions are permitted to be used to determine the wind effects on regularly shaped buildings, or other structures that are regularly shaped, that meet all of the following conditions:

  1. The building or other structure is less than or equal to 75 feet (22 860 mm) in height with a height-to-least-width ratio of 4 or less, or the building or other structure has a fundamental frequency greater than or equal to 1 hertz.
  2. The building or other structure is not sensitive to dynamic effects.
  3. The building or other structure is not located on a site for which channeling effects or buffeting in the wake of upwind obstructions warrant special consideration.
  4. The building shall meet the requirements of a simple diaphragm building as defined in ASCE 7 Section 26.2, where wind loads are only transmitted to the main windforce-resisting system (MWFRS) at the diaphragms.
  5. For open buildings, multispan gable roofs, stepped roofs, sawtooth roofs, domed roofs, roofs with slopes greater than 45 degrees (0.79 rad), solid free-standing walls and solid signs, and rooftop equipment, apply ASCE 7 provisions.
The following modifications shall be made to certain subsections in ASCE 7: in Section 1609A.6.2, symbols and notations that are specific to this section are used in conjunction with the symbols and notations in ASCE 7 Section 26.3.

Coefficients and variables used in the alternative all-heights method equations are as follows:

Cnet= Net-pressure coefficient based on Kd [(G) (Cp) - (GCpi)], in accordance with Table 1609A.6.2.

G = Gust effect factor for rigid structures in accordance with ASCE 7 Section 26.9.1.

Kd = Wind directionality factor in accordance with ASCE 7 Table 26-6.

Pnet= Design wind pressure to be used in determination of wind loads on buildings or other structures or their components and cladding, in psf (kN/m2).

TABLE 1609A.6.2

NET PRESSURE COEFFICIENTS, Cneta,b

STRUCTURE OR PART THEREOFDESCRIPTIONCnet FACTOR
1. Main windforce
-resisting frames and systems
Walls:EnclosedPartially enclosed
+ Internal pressure- Internal pressure+ Internal pressure- Internal pressure
Windward wall0.430.730.111.05
Leeward wall-0.51-0.21-0.830.11
Sidewall-0.66-0.35-0.97-0.04
Parapet wallWindward1.281.28
Leeward-0.85-0.85
Roofs:EnclosedPartially enclosed
Wind perpendicular to ridge+ Internal pressure- Internal pressure+ Internal pressure- Internal pressure
Leeward roof or flat roof-0.66-0.35-0.97-0.04
Windward roof slopes:
Slope < 2:12 (10°)Condition 1-1.09-0.79-1.41-0.47
Condition 2-0.280.02-0.600.34
Slope = 4:12 (18°)Condition 1-0.73-0.42-1.04-0.11
Condition 2-0.050.25-0.370.57
Slope = 5:12 (23°)Condition 1-0.58-0.28-0.900.04
Condition 20.030.34-0.290.65
Slope = 6:12 (27°)Condition 1-0.47-0.16-0.780.15
Condition 20.060.37-0.250.68
Slope = 7:12 (30°)Condition 1-0.37-0.06-0.680.25
Condition 20.070.37-0.250.69
Slope = 9:12 (37°)Condition 1-0.270.04-0.580.35
Condition 20.140.44-0.180.76
Slope = 12:12 (45°)0.140.44-0.180.76
Wind parallel to ridge and flat roofs-1.09-0.79-1.41-0.47
Nonbuilding Structures: Chimneys, Tanks and Similar Structures:
h/D
1725
Square (Wind normal to face)0.991.071.53
Square (Wind on diagonal)0.770.841.15
Hexagonal or Octagonal0.810.971.13
Round0.650.810.97
Open signs and lattice frameworksRatio of solid to gross area
< 0.10.1 to 0.290.3 to 0.7
Flat1.451.301.16
Round0.870.941.08
STRUCTURE OR PART THEREOFDESCRIPTIONCnet FACTOR
2. Components and cladding not in areas of discontinuity— roofs and overhangsRoof elements and slopesEnclosedPartially enclosed
Gable of hipped configurations (Zone 1)
Flat < Slope < 6:12 (27°) See ASCE 7 Figure 30.4-2B Zone 1
Positive10 square feet or less0.580.89
100 square feet or more0.410.72
Negative10 square feet or less-1.00-1.32
100 square feet or more-0.92-1.23
Overhang: Flat < Slope < 6:12 (27°) See ASCE 7 Figure 30.4-2A Zone 1
Negative10 square feet or less-1.45
100 square feet or more-1.36
500 square feet or more-0.94
6:12 (27°) < Slope < 12:12 (45°) See ASCE 7 Figure 30.4-2C Zone 1
Positive10 square feet or less0.921.23
100 square feet or more0.831.15
Negative10 square feet or less-1.00-1.32
100 square feet or more-0.83-1.15
Monosloped configurations (Zone 1)EnclosedPartially enclosed
Flat < Slope < 7:12 (30°) See ASCE 7 Figure 30.4-5B Zone 1
Positive10 square feet or less0.490.81
100 square feet or more0.410.72
Negative10 square feet or less-1.26-1.57
100 square feet or more-1.09-1.40
Tall flat-topped roofs h > 60 feetEnclosedPartially enclosed
Flat < Slope < 2:12 (10°) (Zone 1) See ASCE 7 Figure 30.8-1 Zone 1
Negative10 square feet or less-1.34-1.66
500 square feet or more-0.92-1.23
3. Components and cladding in areas of discontinuities— roofs and overhangs (continued)Gable or hipped configurations at ridges, eaves and rakes (Zone 2)
Flat < Slope < 6:12 (27°) See ASCE 7 Figure 30.4-2B Zone 2
Positive10 square feet or less0.580.89
100 square feet or more0.410.72
Negative10 square feet or less-1.68-2.00
100 square feet or more-1.17-1.49
Overhang for Slope Flat < Slope < 6:12 (27°) See ASCE 7 Figure 30.4-2B Zone 2
Negative10 square feet or less-1.87
100 square feet or more-1.87
6:12 (27°) < Slope < 12:12 (45°) Figure 30.4-2CEnclosedPartially enclosed
Positive10 square feet or less0.921.23
100 square feet or more0.831.15
Negative10 square feet or less-1.17-1.49
100 square feet or more-1.00-1.32
Overhang for 6:12 (27°) < Slope < 12:12 (45°) See ASCE 7 Figure 30.4-2C Zone 2
Negative10 square feet or less-1.70
500 square feet or more-1.53
Roof elements and slopesEnclosedPartially enclosed
Monosloped configurations at ridges, eaves and rakes (Zone 2)
Flat < Slope < 7:12 (30°) See ASCE 7 Figure 30.4-5B Zone 2
Positive10 square feet or less0.490.81
100 square feet or more0.410.72
Negative10 square feet or less-1.51-1.83
100 square feet or more-1.43-1.74
Tall flat topped roofs h > 60 feetEnclosedPartially enclosed
Flat < Slope < 2:12 (10°) (Zone 2) See ASCE 7 Figure 30.8-1 Zone 2
Negative10 square feet or less-2.11-2.42
500 square feet or more-1.51-1.83
Gable or hipped configurations at corners (Zone 3) See ASCE 7 Figure 30.4-2B Zone 3
Flat < Slope < 6:12 (27°)EnclosedPartially enclosed
Positive10 square feet or less0.580.89
100 square feet or more0.410.72
Negative10 square feet or less-2.53-2.85
100 square feet or more-1.85-2.17
Overhang for Slope Flat < Slope < 6:12 (27°) See ASCE 7 Figure 30.4-2B Zone 3
Negative10 square feet or less-3.15
100 square feet or more-2.13
6:12 (27°) < 12:12 (45°) See ASCE 7 Figure 30.4-2C Zone 3
Positive10 square feet or less0.921.23
100 square feet or more0.831.15
Negative10 square feet or less-1.17-1.49
100 square feet or more-1.00-1.32
Overhang for 6:12 (27°) < Slope < 12:12 (45°)EnclosedPartially enclosed
Negative10 square feet or less-1.70
100 square feet or more-1.53
Monosloped Configurations at corners (Zone 3) See ASCE 7 Figure 30.4-5B Zone 3
Flat < Slope < 7:12 (30°)
Positive10 square feet or less0.490.81
100 square feet or more0.410.72
10 square feet or less-2.62-2.93
Negative100 square feet or more-1.85-2.17
Tall flat topped roofs h > 60 feetEnclosedPartially enclosed
Flat < Slope < 2:12 (10°) (Zone 3) See ASCE 7 Figure 30.8-1 Zone 3
Negative10 square feet or less-2.87-3.19
500 square feet or more-2.11-2.42
4. Components and cladding not in areas of discontinuity—walls and parapets (continued)Wall Elements: h < 60 feet (Zone 4) Figure 30.4-1EnclosedPartially enclosed
Positive10 square feet or less1.001.32
500 square feet or more0.751.06
Negative10 square feet or less-1.09-1.40
500 square feet or more-0.83-1.15
Wall Elements: h > 60 feet (Zone 4) See ASCE 7 Figure 30.8-1 Zone 4
Positive20 square feet or less0.921.23
500 square feet or more0.660.98
Negative20 square feet or less-0.92-1.23
500 square feet or more-0.75-1.06
Parapet Walls
Positive2.873.19
Negative-1.68-2.00
5. Components and cladding in areas of discontinuity—walls and parapetsWall elements: h < 60 feet (Zone 5) Figure 30.4-1EnclosedPartially enclosed
Positive10 square feet or less1.001.32
500 square feet or more0.751.06
Negative10 square feet or less-1.34-1.66
500 square feet or more-0.83-1.15
Wall elements: h > 60 feet (Zone 5) See ASCE 7 Figure 30.8-1 Zone 4
Positive20 square feet or less0.921.23
500 square feet or more0.660.98
Negative20 square feet or less-1.68-2.00
500 square feet or more-1.00-1.32
Parapet walls
Positive3.643.95
Negative-2.45-2.76

For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, 1 degree = 0.0175 rad.

  1. Linear interpolation between values in the table is permitted.
  2. Some Cnet values have been grouped together. Less conservative results may be obtained by applying ASCE 7 provisions.

When using the alternative all-heights method, the MWFRS, and components and cladding of every structure shall be designed to resist the effects of wind pressures on the building envelope in accordance with Equation 16A-35.

(Equation 16A-35)

Design wind forces for the MWFRS shall be not less than 16 psf (0.77 kN/m2) multiplied by the area of the structure projected on a plane normal to the assumed wind direction (see ASCE 7 Section 27.4.7 for criteria). Design net wind pressure for components and cladding shall be not less than 16 psf (0.77 kN/m2) acting in either direction normal to the surface.

The MWFRS and the components and cladding of every building or other structure shall be designed for the pressures calculated using Equation 16A-35.
The MWFRS shall be investigated for the torsional effects identified in ASCE 7 Figure 27.4-8.

Velocity pressure exposure coefficient, Kz, shall be determined in accordance with ASCE 7 Section 27.3.1 and the topographic factor, Kzt, shall be determined in accordance with ASCE 7 Section 26.8.

  1. For the windward side of a structure, Kzt and Kz shall be based on height z.
  2. For leeward and sidewalls, and for windward and leeward roofs, Kzt and Kz shall be based on mean roof height h.

For the design of the MWFRS and for components and cladding, the sum of the internal and external net pressure shall be based on the net pressure coefficient, Cnet.

  1. The pressure coefficient, Cnet, for walls and roofs shall be determined from Table 1609A.6.2.
  2. Where Cnet has more than one value, the more severe wind load condition shall be used for design.
When using the alternative all-heights method, wind pressures shall be applied simultaneously on, and in a direction normal to, all building envelope wall and roof surfaces.

Wind pressure for each component or cladding element is applied as follows using Cnet values based on the effective wind area, A, contained within the zones in areas of discontinuity of width and/or length “a,” “2a” or “4a” at: corners of roofs and walls; edge strips for ridges, rakes and eaves; or field areas on walls or roofs as indicated in figures in tables in ASCE 7 as referenced in Table 1609A.6.2 in accordance with the following:

  1. Calculated pressures at local discontinuities acting over specific edge strips or corner boundary areas.
  2. Include “field” (Zone 1, 2 or 4, as applicable) pressures applied to areas beyond the boundaries of the areas of discontinuity.
  3. Where applicable, the calculated pressures at discontinuities (Zone 2 or 3) shall be combined with design pressures that apply specifically on rakes or eave overhangs.

Foundation walls and retaining walls shall be designed to resist lateral soil loads. Soil loads specified in Table 1610.1 shall be used as the minimum design lateral soil loads unless determined otherwise by a geotechnical investigation in accordance with Section 1803A. Foundation walls and other walls in which horizontal movement is restricted at the top shall be designed for at-rest pressure. Retaining walls free to move and rotate at the top shall be permitted to be designed for active pressure. Design lateral pressure from surcharge loads shall be added to the lateral earth pressure load. Design lateral pressure shall be increased if soils at the site are expansive. Foundation walls shall be designed to support the weight of the full hydrostatic pressure of undrained backfill unless a drainage system is installed in accordance with Sections 1805A.4.2 and 1805A.4.3.

Exception: Foundation walls extending not more than 8 feet (2438 mm) below grade and laterally supported at the top by flexible diaphragms shall be permitted to be designed for active pressure.

TABLE 1610A.1

LATERAL SOIL LOAD

DESCRIPTION OF BACKFILL MATERIALcUNIFIED SOIL CLASSIFICATIONDESIGN LATERAL SOIL LOADa (pound per square foot per foot of depth)
Active pressureAt-rest pressure
Well-graded, clean gravels; gravel-sand mixesGW3060
Poorly graded clean gravels; gravel-sand mixesGP3060
Silty gravels, poorly graded gravel-sand mixesGM4060
Clayey gravels, poorly graded gravel-and-clay mixesGC4560
Well-graded, clean sands; gravelly sand mixesSW3060
Poorly graded clean sands; sand-gravel mixesSP3060
Silty sands, poorly graded sand-silt mixesSM4560
Sand-silt clay mix with plastic finesSM-SC45100
Clayey sands, poorly graded sand-clay mixesSC60100
Inorganic silts and clayey siltsML45100
Mixture of inorganic silt and clayML-CL60100
Inorganic clays of low to medium plasticityCL60100
Organic silts and silt clays, low plasticityOLNote bNote b
Inorganic clayey silts, elastic siltsMHNote bNote b
Inorganic clays of high plasticityCHNote bNote b
Organic clays and silty claysOHNote bNote b

For SI: 1 pound per square foot per foot of depth = 0.157 kPa/m, 1 foot = 304.8 mm.

  1. Design lateral soil loads are given for moist conditions for the specified soils at their optimum densities. Actual field conditions shall govern. Submerged or saturated soil pressures shall include the weight of the buoyant soil plus the hydrostatic loads.
  2. Unsuitable as backfill material.
  3. The definition and classification of soil materials shall be in accordance with ASTM D2487.

Each portion of a roof shall be designed to sustain the load of rainwater that will accumulate on it if the primary drainage system for that portion is blocked plus the uniform load caused by water that rises above the inlet of the secondary drainage system at its design flow. The design rainfall shall be based on the 100-year hourly rainfall rate indicated in Figure 1611A.1 or on other rainfall rates determined from approved local weather data.

(Equation 16A-36)

For SI: R = 0.0098(ds + dh)

where:

dh = Additional depth of water on the undeflected roof above the inlet of secondary drainage system at its design flow (i.e., the hydraulic head), in inches (mm).

ds = Depth of water on the undeflected roof up to the inlet of secondary drainage system when the primary drainage system is blocked (i.e., the static head), in inches (mm).

R = Rain load on the undeflected roof, in psf (kN/m2). When the phrase “undeflected roof” is used, deflections from loads (including dead loads) shall not be considered when determining the amount of rain on the roof.

[P] FIGURE 1611A.1

100-YEAR, 1-HOUR RAINFALL (INCHES) WESTERN UNITED STATES

For SI: 1 inch = 25.4 mm.

Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.

[P] FIGURE 1611A.1

100-YEAR, 1-HOUR RAINFALL (INCHES) CENTRAL UNITED STATES

For SI: 1 inch = 25.4 mm.

Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.

[P] FIGURE 1611A.1

100-YEAR, 1-HOUR RAINFALL (INCHES) EASTERN UNITED STATES

For SI: 1 inch = 25.4 mm.

Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.

[P] FIGURE 1611A.1

100-YEAR, 1-HOUR RAINFALL (INCHES) ALASKA

For SI: 1 inch = 25.4 mm.

Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.

[P] FIGURE 1611A.1

100-YEAR, 1-HOUR RAINFALL (INCHES) HAWAII

For SI: 1 inch = 25.4 mm.

Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.

Susceptible bays of roofs shall be evaluated for ponding instability in accordance with Section 8.4 of ASCE 7.
Roofs equipped with hardware to control the rate of drainage shall be equipped with a secondary drainage system at a higher elevation that limits accumulation of water on the roof above that elevation. Such roofs shall be designed to sustain the load of rainwater that will accumulate on them to the elevation of the secondary drainage system plus the uniform load caused by water that rises above the inlet of the secondary drainage system at its design flow determined from Section 1611A.1. Such roofs shall also be checked for ponding instability in accordance with Section 1611A.2.
Within flood hazard areas as established in Section 1612A.3, all new construction of buildings, structures and portions of buildings and structures, including substantial improvement and restoration of substantial damage to buildings and structures, shall be designed and constructed to resist the effects of flood hazards and flood loads. For buildings that are located in more than one flood hazard area, the provisions associated with the most restrictive flood hazard area shall apply.

The following words and terms are defined in Chapter 2.

BASE FLOOD.

BASE FLOOD ELEVATION.

BASEMENT.

COASTAL A ZONE.

COASTAL HIGH HAZARD AREA.

DESIGN FLOOD.

DESIGN FLOOD ELEVATION.

DRY FLOODPROOFING.

EXISTING CONSTRUCTION.

EXISTING STRUCTURE.

FLOOD or FLOODING.

FLOOD DAMAGE-RESISTANT MATERIALS.

FLOOD HAZARD AREA.

FLOOD INSURANCE RATE MAP (FIRM).

FLOOD INSURANCE STUDY.

FLOODWAY.

LOWEST FLOOR.

SPECIAL FLOOD HAZARD AREA.

START OF CONSTRUCTION.

SUBSTANTIAL DAMAGE.

SUBSTANTIAL IMPROVEMENT.

To establish flood hazard areas, the applicable governing authority shall adopt a flood hazard map and supporting data. The flood hazard map shall include, at a minimum, areas of special flood hazard as identified by the Federal Emergency Management

Agency’s Flood Insurance Study (FIS) adopted by the local authority having jurisdiction where the project is located, as amended or revised with the accompanying Flood Insurance Rate Map (FIRM) and Flood Boundary and Floodway Map (FBFM) and related supporting data along with any revisions thereto. The adopted flood hazard map and supporting data are hereby adopted by reference and declared to be part of this section.

Where design flood elevations are not included in the flood hazard areas established in Section 1612A.3, or where floodways are not designated, the building official is authorized to require the applicant to:

  1. Obtain and reasonably utilize any design flood elevation and floodway data available from a federal, state or other source; or
  2. Determine the design flood elevation and/or flood-way in accordance with accepted hydrologic and hydraulic engineering practices used to define special flood hazard areas. Determinations shall be undertaken by a registered design professional who shall document that the technical methods used reflect currently accepted engineering practice.
In riverine flood hazard areas where design flood elevations are specified but floodways have not been designated, the applicant shall provide a floodway analysis that demonstrates that the proposed work will not increase the design flood elevation more than 1 foot (305 mm) at any point within the jurisdiction of the applicable governing authority.
The design and construction of buildings and structures located in flood hazard areas, including coastal high hazard areas and coastal A zones, shall be in accordance with Chapter 5 of ASCE 7 and ASCE 24.

The following documentation shall be prepared and sealed by a registered design professional and submitted to the building official:

  1. For construction in flood hazard areas other than coastal high hazard areas or coastal A zones:

    1. 1.1. The elevation of the lowest floor, including the basement, as required by the lowest floor elevation inspection in Section 110.3.3 and for the final inspection in Section 110.3.10.1.
    2. 1.2. For fully enclosed areas below the design flood elevation where provisions to allow for the automatic entry and exit of floodwaters do not meet the minimum requirements in Section 2.6.2.1 of ASCE 24, construction documents shall include a statement that the design will provide for equalization of hydrostatic flood forces in accordance with Section 2.6.2.2 of ASCE 24.
    3. 1.3. For dry floodproofed nonresidential buildings, construction documents shall include a statement that the dry floodproofing is designed in accordance with ASCE 24.
  2. For construction in coastal high hazard areas and coastal A zones:

    1. 2.1. The elevation of the bottom of the lowest horizontal structural member as required by the lowest floor elevation inspection in Section 110.3.3and for the final inspection in Section 110.3.10.1.
    2. 2.2. Construction documents shall include a statement that the building is designed in accordance with ASCE 24, including that the pile or column foundation and building or structure to be attached thereto is designed to be anchored to resist flotation, collapse and lateral movement due to the effects of wind and flood loads acting simultaneously on all building components, and other load requirements of Chapter 16.
    3. 2.3. For breakaway walls designed to have a resistance of more than 20 psf (0.96 kN/m2) determined using allowable stress design, construction documents shall include a statement that the breakaway wall is designed in accordance with ASCE 24.

Every structure, and portion thereof, including nonstructural components that are permanently attached to structures and their supports and attachments, shall be designed and constructed to resist the effects of earthquake motions in accordance with ASCE 7 with all the modifications incorporated herein, excluding Chapter 14 and Appendix 11A. The seismic design category for a structure shall be determined in accordance with Section 1613A.

Exception: Structures that require special consideration of their response characteristics and environment that are not addressed by this code or ASCE 7 and for which other regulations provide seismic criteria, such as vehicular bridges, electrical transmission towers, hydraulic structures, buried utility lines and their appurtenances and nuclear reactors.

The following terms are defined in Chapter 2, except those defined below which shall, for the purposes of this section, have the meanings shown herein. Definition provided in ASCE 7 Section 11.2 and [OSHPD 1 & 4] Section 3402A.1 shall apply when appropriate in addition to terms defined in this section.

ACTIVE EARTHQUAKE FAULT. A fault that has been the source of earthquakes or is recognized as a potential source of earthquakes, including those that have exhibited surface displacement within Holocene time (about 11,000 years) as determined by California Geological Survey (CGS) under the Alquist-Priolo Earthquake Fault Zoning Act, those included as type A or type B faults for the U.S. Geological Survey (USGS) National Seismic Hazard Maps, and faults considered to have been active in Holocene time by any authoritative source, federal, state or local governmental agency.

BASE. See ASCE 7.

DESIGN EARTHQUAKE GROUND MOTION.

DISTANCE FROM AN ACTIVE EARTHQUAKE FAULT. Distance measured from the nearest point of the building to the closest edge of an Alquist-Priolo Earthquake Fault Zone for an active fault, if such a map exists, or to the closest mapped splay of the fault.

GENERAL ACUTE CARE HOSPITAL. See Section 1224.3.

IRREGULAR STRUCTURE. A structure designed as having one or more plan or vertical irregularities per ASCE 7 Section 12.3.

MECHANICAL SYSTEMS.

ORTHOGONAL.

RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATION.

SEISMIC DESIGN CATEGORY.

SEISMIC FORCE-RESISTING SYSTEM.

SITE CLASS.

SITE COEFFICIENTS.

Seismic ground motion values shall be determined in accordance with this section.
The parameters SS and S1 shall be determined from the 0.2 and 1-second spectral response accelerations shown on Figures 1613.3.1(1) through 1613.3.1(6).

Based on the site soil properties, the site shall be classified as Site Class A, B, C, D, E or F in accordance with Chapter 20 of ASCE 7.

Where the soil properties are not known in sufficient detail to determine the site class, Site Class D shall be used unless the building official or geotechnical data determines Site Class E or F soils are present at the site.

The maximum considered earthquake spectral response acceleration for short periods, SMS, and at 1-second period, SM1, adjusted for site class effects shall be determined by Equations 16A-37 and 16A-38, respectively:

(Equation 16A-37)

(Equation 16A-38)

where:

Fa = Site coefficient defined in Table 1613A.3.3(1).

Fv = Site coefficient defined in Table 1613A.3.3(2).

SS = The mapped spectral accelerations for short periods as determined in Section 1613A.3.1.

S1 = The mapped spectral accelerations for a 1-second period as determined in Section 1613A.3.1.

TABLE 1613A.3.3(1)

VALUES OF SITE COEFFICIENT Faa

SITE CLASSMAPPED SPECTRAL RESPONSE ACCELERATION AT SHORT PERIOD
Ss ≤ 0.25Ss = 0.50Ss = 0.75Ss = 1.00Ss ≥ 1.25
A0.80.80.80.80.8
B1.01.01.01.01.0
C1.21.21.11.01.0
D1.61.41.21.11.0
E2.51.71.20.90.9
FNote bNote bNote bNote bNote b
  1. Use straight-line interpolation for intermediate values of mapped spectral response acceleration at short period, SS.
  2. Values shall be determined in accordance with Section 11.4.7 of ASCE 7.

TABLE 1613A.3.3(2)

VALUES OF SITE COEFFICIENT FVa

SITE CLASSMAPPED SPECTRAL RESPONSE ACCELERATION AT 1-SECOND PERIOD
S1 ≤ 0.1S1 = 0.2S1 = 0.3S1 = 0.4S1 ≥ 0.5
A0.80.80.80.80.8
B1.01.01.01.01.0
C1.71.61.51.41.3
D2.42.01.81.61.5
E3.53.22.82.42.4
FNote bNote bNote bNote bNote b
  1. Use straight-line interpolation for intermediate values of mapped spectral response acceleration at 1-second period, S1.
  2. Values shall be determined in accordance with Section 11.4.7 of ASCE 7.

Five-percent damped design spectral response acceleration at short periods, SDS , and at 1-second period, SD1 , shall be determined from Equations 16A-39 and 16A-40, respectively:

(Equation 16A-39)

(Equation 16A-40)

where:

SMS = The maximum considered earthquake spectral response accelerations for short period as determined in Section 1613A.3.3.

SM1 = The maximum considered earthquake spectral response accelerations for 1-second period as determined in Section 1613A.3.3.

Structures classified as Risk Category I, II or III that are located where the mapped spectral response acceleration parameter at 1-second period, S1, is greater than or equal to 0.75 shall be assigned to Seismic Design Category E. Structures classified as Risk Category IV that are located where the mapped spectral response acceleration parameter at 1-second period, S1, is greater than or equal to 0.75 shall be assigned to Seismic Design Category F. All other structures shall be assigned to Seismic Design Category D.
Not permitted by DSA-SS and OSHPD.
Not permitted by DSA-SS and OSHPD.
The provisions of Section 1613A.4 shall be permitted as alternatives to the relevant provisions of ASCE 7.

Add the following exception to the end of Section 17.5.4.2 of ASCE 7:

Exception: For isolated structures designed in accordance with this standard, the Structural System Limitations and the Building Height Limitations in Table 12.2-1 for ordinary steel concentrically braced frames (OCBFs) as defined in Chapter 11 and intermediate moment frames (IMFs) as defined in Chapter 11 are permitted to be taken as 160 feet (48 768 mm) for structures assigned to Seismic Design Category D, E or F, provided that the following conditions are satisfied:

  1. The value of RI as defined in Chapter 17 is taken as 1.
  2. For OCBFs, design is in accordance with AISC 341.
  3. For IMFs, design is in accordance with AISC 341. In addition, requirements of Section E3.6e of AISC 341 shall be satisfied.
The provisions of Section 1613.5 shall be permitted as an amendment to the relevant provisions of ASCE 7.

Modify ASCE 7 Section 12.11.2.2.1 as follows:

12.11.2.2.1 Transfer of anchorage forces into diaphragm. Diaphragms shall be provided with continuous ties or struts between diaphragm chords to distribute these anchorage forces into the diaphragms. Diaphragm connections shall be positive, mechanical or welded. Added chords are permitted to be used to form subdiaphragms to transmit the anchorage forces to the main continuous cross-ties. The maximum length-to-width ratio of a wood, wood structural panel or untopped steel deck sheathed structural subdiaphragm that serves as part of the continuous tie system shall be 2.5 to 1. Connections and anchorages capable of resisting the prescribed forces shall be provided between the diaphragm and the attached components. Connections shall extend into the diaphragm a sufficient distance to develop the force transferred into the diaphragm.

Ballasted, roof-mounted photovoltaic panel systems need not be rigidly attached to the roof or supporting structure. Ballasted non-penetrating systems shall be designed and installed only on roofs with slopes not more than one unit vertical in 12 units horizontal. Ballasted nonpenetrating systems shall be designed to resist sliding and uplift resulting from lateral and vertical forces as required by Section 1605, using a coefficient of friction determined by acceptable engineering principles. In structures assigned to Seismic Design Category D, E or F, ballasted nonpenetrating systems shall be designed to accommodate seismic displacement determined by nonlinear response-history analysis or shake-table testing, using input motions consistent with ASCE 7 lateral and vertical seismic forces for nonstructural components on roofs.

[OSHPD 1 & 4] Ballasted photovoltaic panel systems shall be considered as an alternative system.

Ice-sensitive structures shall be designed for atmospheric ice loads in accordance with Chapter 10 of ASCE 7.
High-rise buildings that are assigned to Risk Category III or IV shall comply with the requirements of this section. Frame structures shall comply with the requirements of Section 1615A.3. Bearing wall structures shall comply with the requirements of Section 1615A.4.

The following words and terms are defined in Chapter 2, except those defined below which shall, for the purposes of this section, have the meanings shown herein.

BEARING WALL STRUCTURE.

FRAME STRUCTURE.

HIGH-RISE BUILDING. A building with an occupied floor located more than 75 feet (22 860 mm) above the base.

Frame structures shall comply with the requirements of this section.

Frame structures constructed primarily of reinforced or prestressed concrete, either cast-in-place or precast, or a combination of these, shall conform to the requirements of Section 4.10 of ACI 318. Where ACI 318 requires that nonprestressed reinforcing or prestressing steel pass through the region bounded by the longitudinal column reinforcement, that reinforcing or prestressing steel shall have a minimum nominal tensile strength equal to two-thirds of the required one-way vertical strength of the connection of the floor or roof system to the column in each direction of beam or slab reinforcement passing through the column.

Exception: Where concrete slabs with continuous reinforcement having an area not less than 0.0015 times the concrete area in each of two orthogonal directions are present and are either monolithic with or equivalently bonded to beams, girders or columns, the longitudinal reinforcing or prestressing steel passing through the column reinforcement shall have a nominal tensile strength of one-third of the required one-way vertical strength of the connection of the floor or roof system to the column in each direction of beam or slab reinforcement passing through the column.

Frame structures constructed with a structural steel frame or a frame composed of open web steel joists, joist girders with or without other structural steel elements or a frame composed of composite steel or composite steel joists and reinforced concrete elements shall conform to the requirements of this section.
Each column splice shall have the minimum design strength in tension to transfer the design dead and live load tributary to the column between the splice and the splice or base immediately below.

End connections of all beams and girders shall have a minimum nominal axial tensile strength equal to the required vertical shear strength for allowable stress design (ASD) or two-thirds of the required shear strength for load and resistance factor design (LRFD) but not less than 10 kips (45 kN). For the purpose of this section, the shear force and the axial tensile force need not be considered to act simultaneously.

Exception: Where beams, girders, open web joist and joist girders support a concrete slab or concrete slab on metal deck that is attached to the beam or girder with not less than 3/8-inch-diameter (9.5 mm) headed shear studs, at a spacing of not more than 12 inches (305 mm) on center, averaged over the length of the member, or other attachment having equivalent shear strength, and the slab contains continuous distributed reinforcement in each of two orthogonal directions with an area not less than 0.0015 times the concrete area, the nominal axial tension strength of the end connection shall be permitted to be taken as half the required vertical shear strength for ASD or one-third of the required shear strength for LRFD, but not less than 10 kips (45 kN).

Bearing wall structures shall have vertical ties in all load-bearing walls and longitudinal ties, transverse ties and perimeter ties at each floor level in accordance with this section and as shown in Figure 1615A.4.

FIGURE 1615A.4

LONGITUDINAL, PERIMETER, TRANSVERSE AND VERTICAL TIES

Precast bearing wall structures constructed solely of reinforced or prestressed concrete, or combinations of these shall conform to the requirements of Sections 16.2.4 and 16.2.5 of ACI 318.
Ties in bearing wall structures other than those covered in Section 1615A.4.1 shall conform to this section.

Longitudinal ties shall consist of continuous reinforcement in slabs; continuous or spliced decks or sheathing; continuous or spliced members framing to, within or across walls; or connections of continuous framing members to walls. Longitudinal ties shall extend across interior load-bearing walls and shall connect to exterior load-bearing walls and shall be spaced at not greater than 10 feet (3038 mm) on center. Ties shall have a minimum nominal tensile strength, TT, given by Equation 16A-41. For ASD the minimum nominal tensile strength shall be permitted to be taken as 1.5 times the allowable tensile stress times the area of the tie.

(Equation 16A-41)

where:

L = The span of the horizontal element in the direction of the tie, between bearing walls, feet (m).

w = The weight per unit area of the floor or roof in the span being tied to or across the wall, psf (N/m2).

S = The spacing between ties, feet (m).

αT = A coefficient with a value of 1,500 pounds per foot (2.25 kN/m) for masonry bearing wall structures and a value of 375 pounds per foot (0.6 kN/m) for structures with bearing walls of cold-formed steel light-frame construction.

Transverse ties shall consist of continuous reinforcement in slabs; continuous or spliced decks or sheathing; continuous or spliced members framing to, within or across walls; or connections of continuous framing members to walls. Transverse ties shall be placed no farther apart than the spacing of load-bearing walls. Transverse ties shall have minimum nominal tensile strength TT, given by Equation 16A-41. For ASD the minimum nominal tensile strength shall be permitted to be taken as 1.5 times the allowable tensile stress times the area of the tie.

Perimeter ties shall consist of continuous reinforcement in slabs; continuous or spliced decks or sheathing; continuous or spliced members framing to, within or across walls; or connections of continuous framing members to walls. Ties around the perimeter of each floor and roof shall be located within 4 feet (1219 mm) of the edge and shall provide a nominal strength in tension not less than Tp, given by Equation 16A-42. For ASD the minimum nominal tensile strength shall be permitted to be taken as 1.5 times the allowable tensile stress times the area of the tie.

(Equation 16A-42)

For SI: Tp = 90.7w ≤ βT

where:

w = As defined in Section 1614A.4.2.1.

βT = A coefficient with a value of 16,000 pounds (7200 kN) for structures with masonry bearing walls and a value of 4,000 pounds (1300 kN) for structures with bearing walls of cold-formed steel light-frame construction.

Vertical ties shall consist of continuous or spliced reinforcing, continuous or spliced members, wall sheathing or other engineered systems. Vertical tension ties shall be provided in bearing walls and shall be continuous over the height of the building. The minimum nominal tensile strength for vertical ties within a bearing wall shall be equal to the weight of the wall within that story plus the weight of the diaphragm tributary to the wall in the story below. No fewer than two ties shall be provided for each wall. The strength of each tie need not exceed 3,000 pounds per foot (450 kN/m) of wall tributary to the tie for walls of masonry construction or 750 pounds per foot (140 kN/m) of wall tributary to the tie for walls of cold-formed steel light-frame construction.

The text of ASCE 7 shall be modified as indicated in Sections 1616A.1.1 through 1616A.1.40.

Modify ASCE 7 Section 1.3 by the adding Section 1.3.6 as follows:

1.3.6 Structural design criteria. Where design is based on ASCE 7, Chapters 16, 17 or 18, the ground motion, analysis, and design methods, material assumptions, testing requirements, and acceptance criteria proposed by the engineer shall be submitted to the enforcement agency in the form of structural design criteria for approval. [DSA-SS] Structural design criteria including wind tunnel design recommendations are required where design is based on ASCE 7 Chapter 31.

[DSA-SS] Peer review requirements in Section 322 of the California Existing Building Code shall apply to design reviews required by ASCE 7 Chapters 17 and 18.

[OSHPD 1 & 4] Peer review requirements in Section 3414A of this code shall apply to design reviews required by ASCE 7 Chapters 17 and 18.

Replace last paragraph of ASCE 7, Section 11.1.3, by the following:

Buildings shall be designed and detailed in accordance with Chapter 12.

Modify ASCE 7 Section 11.4.7 by adding the following:

For buildings assigned to Seismic Design Category E or F, or when required by the building official, a ground motion hazard analysis shall be performed in accordance with ASCE 7 Chapter 21 as modified by Section 1803A.6 of this code.

Modify ASCE 7 Table 12.2-1 as follows:

  1. BEARING WALL SYSTEMS

    • Intermediate Precast Shear Walls—Not permitted by OSHPD.
    • Light-framed walls with shear panels of all other materials—Not permitted by OSHPD and DSA-SS.
  2. BUILDING FRAME SYSTEMS

    • Ordinary steel concentrically braced frames— Not permitted by OSHPD.
    • Intermediate Precast Shear Walls—Not permitted by OSHPD.
    • Light-framed walls with shear panels of all other materials—Not permitted by OSHPD and DSA-SS.
    • Special steel plate shear wall—Not permitted by OSHPD.
  3. MOMENT-RESISTING FRAME SYSTEMS

    • Special steel truss moment frames—Not permitted by OSHPD.
    • Intermediate steel moment frames—Not permitted by OSHPD.
    • Ordinary steel moment frames—Not permitted by OSHPD.
    • Cold-formed steel–special bolted moment frame - Not permitted by DSA-SS and OSHPD.

Exceptions:

  1. Systems listed in this section can be used as an alternative system when preapproved by the enforcement agency.
  2. Rooftop or other supported structures not exceeding two stories in height and 10 percent of the total structure weight can use the systems in this section when designed as components per ASCE 7 Chapter 13.
  3. Systems listed in this section can be used for seismically isolated buildings when permitted by Section 1613A.4.1.

Replace ASCE 7, Section 12.2.3.1, Items 1 and 2, by the following:

The value of the response modification coefficient, R, used for design at any story shall not exceed the lowest value of R that is used in the same direction at any story above that story. Likewise, the deflection amplification factor, Cd, and the system over strength factor, Ω0, used for the design at any story shall not be less than the largest value of these factors that are used in the same direction at any story above that story.

Modify ASCE 7, Section 12.2.3.2, by adding the following additional requirements:

f. Where design of elements of the upper portion is governed by special seismic load combinations, the special loads shall be considered in the design of the lower portion.

[DSA-SS] The exception after the first paragraph is not permitted by DSA-SS.

[DSA-SS] The exception after the first paragraph is not permitted by DSA-SS.

[DSA-SS] The exception after the first paragraph is not permitted by DSA-SS.

Modify first sentence of ASCE 7, Section 12.3.3.1, as follows:

12.3.3.1 Prohibited horizontal and vertical irregularities for Seismic Design Categories D through F. Structures assigned to Seismic Design Category D, E or F having horizontal structural irregularity Type 1b of Table 12.3-1 or vertical structural irregularities Type 1b, 5a or 5b of Table 12.3-2 shall not be permitted.

Modify ASCE 7, Section 12.7.2, by adding Item 6 to read as follows:

6. Where buildings provide lateral support for walls retaining earth, and the exterior grades on opposite sides of the building differ by more than 6 feet (1829 mm), the load combination of the seismic increment of earth pressure due to earthquake acting on the higher side, as determined by a geotechnical engineer qualified in soils engineering plus the difference in earth pressures shall be added to the lateral forces provided in this section.

Replace ASCE 7, Section 12.8.1.3, by the following:

12.8.1.3 Maximum SDS value in determination of Cs and Ev. The value of Cs and Ev are permitted to be calculated using a value of SDS equal to 1.0, but not less than 70% of SDS as defined in Section 11.4.4, provided that all of the following criteria are met:

  1. The structure does not have irregularities, as defined in Section 12.3.2;
  2. The structure does not exceed five stories above the base as defined in Section 11.2;
  3. The structure has a fundamental period, T, that does not exceed 0.5 seconds, as determined using Section 12.8.2;
  4. The structure meets the requirements necessary for the redundancy factor, ρ, to be permitted to be taken as 1.0, in accordance with Section 12.3.4.2;
  5. The site soil properties are not classified as Site Class E or F, as defined in Section 11.4.2; and
  6. The structure is classified as Risk Category I or II, as defined in Section 1.5.1.
  7. [OSHPD 1 & 4] The structure is a nonconforming building not supporting SPC-3 or higher buildings.

Replace ASCE 7 Section 12.9.4 as follows:

12.9.4 Scaling design values of combined response. Modal base shears used to determine forces and drifts shall not be less than the base shear calculated using the equivalent lateral force procedure of Section 12.8.

Replace ASCE 7, Exception 1 of Section 12.10.2.1, by adding the following:

Exception:

  1. The forces calculated above need not exceed those calculated using the load combinations of Section 12.4.3.2 with seismic forces determined by Equation 12.10-3 and transfer forces, where applicable.

[OSHPD 1 & 4] Replace ASCE 7 Equation 12.12-1 by the following:

(Equation 12.12-1)

Modify ASCE 7 Section 12.13.1 by adding Section 12.13.1.1 as follows:

12.13.1.1 Foundations and superstructure-to-foundation connections. The foundation shall be capable of transmitting the design base shear and the overturning forces from the structure into the supporting soil. Stability against overturning and sliding shall be in accordance with Section 1605A.1.1.

In addition, the foundation and the connection of the superstructure elements to the foundation shall have the strength to resist, in addition to gravity loads, the lesser of the following seismic loads:

  1. The strength of the superstructure elements.
  2. The maximum forces that can be delivered to the foundation in a fully yielded structural system.
  3. Forces from the load combinations with over-strength factor in accordance with ASCE 7, Section 12.4.3.2.

Exceptions:

  1. Where referenced standards specify the use of higher design loads.
  2. When it can be demonstrated that inelastic deformation of the foundation and superstructure-to-foundation connection will not result in a weak story or cause collapse of the structure.
  3. Where seismic force-resisting system consists of light framed walls with shear panels, unless the reference standard specifies the use of higher design loads.

Where the computation of the seismic overturning moment is by the equivalent lateral-force method or the modal analysis method, reduction in overturning moment permitted by section 12.13.4 of ASCE 7 may be used.

Where moment resistance is assumed at the base of the superstructure elements, the rotation and flexural deformation of the foundation as well as deformation of the superstructure-to-foundation connection shall be considered in the drift and deformation compatibility analyses.

[OSHPD 1 & 4] Modify ASCE 7 Section 13.1.3 by the following:

All nonstructural components shall have a component importance factor, Ip, equal to 1.5.

Exception: Freestanding skilled nursing or acute psychiatric buildings, not providing services/systems, utilities, or access/egress to general acute care buildings designated as SPC 3 or higher in accordance with Chapter 6 of the California Administrative Code, shall be permitted to use component importance factor, Ip, as shown in Table 1616A.1.17.

TABLE 1616A.1.17

COMPONENT IMPORTANCE FACTOR (Ip)1 FOR FREESTANDING SKILLED NURSING AND ACUTE PSYCHIATRIC BUILDINGS

DESCRIPTIONIMPORTANCE FACTOR (Ip)1
Architectural components1.0
Mechanical and electrical components1.5
Medical devices1.5
Piping, including in-line components1.5
HVAC ducts, including in-line components1.0
Electrical raceways1.0
  1. Components required for life-safety purposes after an earthquake, including emergency and standby power systems, mechanical smoke removal systems, fire protection sprinkler systems, fire alarm control panels, and egress stairways shall have a component importance factor (Ip) of 1.5.

Replace ASCE 7, Section 13.1.4, with the following:

13.1.4 Exemptions. The following nonstructural components are exempt from the requirements of this section:

  1. Furniture (except storage cabinets as noted in Table 13.5-1).
  2. Temporary or moveable (mobile) equipment.

    Exceptions:

    1. Equipment shall be anchored if it is permanently attached to the building utility services such as electricity, gas or water. For the purposes of this requirement, “permanently attached” shall include all electrical connections except plugs for duplex receptacles.
    2. The enforcement agency shall be permitted to require temporary attachments for movable equipment which is usually stationed in one place and heavier than 400 pounds or has a center of mass located 4 feet (1.22 m) or more above the adjacent floor or roof level that directly support the component, when they are not in use for a period longer than 8 hours at a time.
  3. Architectural, mechanical and electrical components in Seismic Design Categories D, E or F where all of the following apply:

    1. The component is positively attached to the structure;
    2. Flexible connections are provided at seismic separation joints and between the component and associated ductwork, piping and conduit; and either:

      1. The component weighs 400 pounds (1780 N) or less and has a center of mass located 4 feet (1.22 m) or less above the adjacent floor or roof level that directly support the component;

        Exception: Special Seismic Certification requirements of this code in accordance with Section 1705A.13.3 shall be applicable.

        or

      2. The component weighs 20 pounds (89 N) or less or, in the case of a distributed system, 5 lb/ft (73 N/m) or less.

Exception: The enforcement agency shall be permitted to require attachments for equipment with hazardous contents to be shown on construction documents irrespective of weight.

Replace ASCE 7, Sections 13.4.2.3, with the following:

13.4.2.3 Prequalified post-installed anchors and specialty inserts in concrete and masonry.

Post-installed anchors and specialty inserts in concrete that are pre-qualified for seismic applications in accordance with ACI 355.2, ACI 355.4, ICC-ES AC193, ICC-ES AC232, ICC-ES AC308 or ICC-ES AC446 shall be permitted. Post-installed anchors in masonry shall be pre-qualified for seismic applications in accordance with ICC-ES AC01, AC58 or AC106.

Use of screw anchors shall be limited to dry interior conditions and shall not be used in building enclosures. Re-use of screw anchors or screw anchor holes shall not be permitted.

Exception: [DSA-SS] Screw anchors are not prohibited for use in building enclosures.

Modify ASCE 7 Section 13.4.5 by adding Section 13.4.5.1 as follows:

13.4.5.1 Power actuated fasteners. Power actuated fasteners qualified in accordance with ICC-ES AC 70 shall be deemed to satisfy the requirements of Section 13.4.5.

Power actuated fasteners shall be permitted in seismic shear for components exempt from permit requirements by Section 1616A.1.18 of this code and for interior non-bearing non-shear wall partitions only. Power actuated fastener shall not be used to anchor seismic bracing, exterior cladding or curtain wall systems.

Exception: Power actuated fasteners in steel to steel connections prequalified for seismic application by cyclic tests in accordance with ICC-ES AC 70 shall be permitted for seismic design.

Replace ASCE 7, Section 13.5.6 with the following:

13.5.6 Suspended ceilings. Suspended ceilings shall be in accordance with this section.

13.5.6.1 Seismic forces. The weight of the ceiling, Wp, shall include the ceiling grid; ceiling tiles or panels; light fixtures if attached to, clipped to, or laterally supported by the ceiling grid; and other components that are laterally supported by the ceiling. Wp shall be taken as not less than 4 psf (19 N/m2).

The seismic force, Fp, shall be transmitted through the ceiling attachments to the building structural elements or the ceiling-structure boundary.

13.5.6.2 Seismic design requirements. Suspended acoustical tile or lay-in panel ceilings shall be designed in accordance with ASTM E580, Section 5.2.8, and the requirements of Sections 13.5.6.2.1 and 13.5.6.2.2, or be designed in accordance with Section 13.2.1.(1), or be seismically qualified in accordance with Sections 13.2.5 or 13.2.6.

13.5.6.2.1 Industry standard construction for acoustical tile or lay-in panel ceilings. Acoustical tile or lay-in panel ceilings in Seismic Design Categories D, E, and F shall be designed and installed in accordance with ASTM C635, ASTM C636, and ASTM E580, Section 5 - Seismic Design Categories D, E, and F as modified by Section 13.5.6.2.2.

Exception to Section 13.5.8.1 shall not be used in accordance with ASTM E580 Section 5.5.

13.5.6.2.2 Modification to ASTM E580. Modify ASTM E580 by the following:

  1. Exitways. Lay-in ceiling assemblies in exit-ways of hospitals and essential services buildings shall be installed with a main runner or cross runner surrounding all sides of each piece of tile, board or panel and each light fixture or grille. A cross runner that supports another cross runner shall be considered as a main runner for the purpose of structural classification. Splices or intersections of such runners shall be attached with through connectors such as pop rivets, screws, pins, plates with end tabs or other approved connectors. Lateral force diagonal bracing may be omitted in the short or transverse direction of exitways, not exceeding 8 feet wide, when perimeter support in accordance with ASTM E580 Sections 5.2.2 and 5.2.3 is provided and the perimeter wall laterally supporting the ceiling in the short or transverse direction is designed to carry the ceiling lateral forces. The connections between the ceiling grid, wall angle and the wall shall be designed to resist the ceiling lateral forces.
  2. Corridors and lobbies. Expansion joints shall be provided in the ceiling at intersections of corridors and at junctions of corridors and lobbies or other similar areas.
  3. Lay-in panels. Metal panels and panels weighing more than 1/2 pounds per square foot (24 N/m2) other than acoustical tiles shall be positively attached to the ceiling suspension runners.
  4. Lateral force bracing. Lateral force bracing is required for all ceiling areas except that they shall be permitted to be omitted in rooms with floor areas up to 144 square feet when perimeter support in accordance with ASTM E580, Sections 5.2.2 and 5.2.3, are provided and perimeter walls are designed to carry the ceiling lateral forces. The connections between the ceiling grid, wall angle and the wall shall be designed to resist the ceiling lateral forces. Horizontal restraint point spacing shall be justified by analysis or test and shall not exceed a spacing of 12 feet by 12 feet. Bracing wires shall be secured with four tight twists in 11/2 inches, or an approved alternate connection.
  5. Ceiling support and bracing wires shall be spaced a minimum of 6” from all pipes, ducts, conduits and equipment that are not braced for horizontal forces, unless approved otherwise by the building official.

[OSHPD 1 & 4] Modify ASCE 7, Section 13.5.7, by the following:

All access floors shall be special access floors in accordance with Section 13.5.7.2.

Modify ASCE 7, Tables 13.5-1 & 13.6-1 by the following:

  1. For components with Rp greater than 1.5, over-strength factor (Ω0) for design of anchorage to concrete and vibration isolators along with associated snubbers/connections shall be 2.0.
  2. For Exterior Nonstructural Wall Elements and Connections, overstrength factor (Ω0) shall be 1.0.

Modify ASCE 7, Section 13.6.5.6, Exceptions 1 and 2, as follows:

Exceptions:

  1. Design for the seismic forces of Section 13.3 shall not be required for raceways where either:

    1. Trapeze assemblies are used to support raceways and the total weight of the race-way supported by trapeze assemblies is less than 10 lb/ft (146 N/m), or
    2. The raceway is supported by hangers and each hanger in the raceway run is 12 in. (305 mm) or less in length from the race-way support point to the supporting structure. Where rod hangers are used with a diameter greater than 3/8 inch, they shall be equipped with swivels to prevent inelastic bending in the rod.
  2. Design for the seismic forces of Section 13.3 shall not be required for conduit, regardless of the value of Ip , where the conduit is up to 2.5 in. (64 mm) trade size.

Replace ASCE 7, Section 13.6.7, Exceptions 1 and 2, with the following:

Exceptions:

The following exceptions pertain to ductwork not designed to carry toxic, highly toxic, or flammable gases or used for smoke control:

  1. Design for the seismic forces of Section 13.3 shall not be required for ductwork where either:

    1. Trapeze assemblies are used to support ductwork and the total weight of the ductwork supported by trapeze assemblies is less than 10 lb/ft (146 N/m); or
    2. The ductwork is supported by hangers and each hanger in the duct run is 12 in. (305 mm) or less in length from the duct support point to the supporting structure. Where rod hangers are used with a diameter greater than 3/8 inch, they shall be equipped with swivels to prevent inelastic bending in the rod.
  2. Design for the seismic forces of Section 13.3 shall not be required where provisions are made to avoid impact with larger ducts or mechanical components or to protect the ducts in the event of such impact; and HVAC ducts have a cross-sectional area of 6 ft2 (0.557 m2) or less, or weigh 10 lb/ft (146 N/m) or less.

Replace ASCE 7, Section 13.6.8.3 with the following:

13.6.8.3 Exceptions. Design of piping systems and attachments for the seismic forces of Section 13.3 shall not be required where one of the following conditions apply:

  1. Trapeze assemblies are used to support piping whereby no single pipe exceeds the limits set forth in 3a. or b. below and the total weight of the piping supported by the trapeze assemblies is less than 10 lb/ft (146 N/m).
  2. The piping is supported by hangers and each hanger in the piping run is 12 in. (305 mm) or less in length from the top of the pipe to the supporting structure. Where pipes are supported on a trapeze, the trapeze shall be supported by hangers having a length of 12 in. (305 mm) or less. Where rod hangers are used with a diameter greater than 3/8 inch, they shall be equipped with swivels, eye nuts or other devices to prevent bending in the rod.
  3. Piping having an Rp in Table 13.6-1 of 4.5 or greater is used and provisions are made to avoid impact with other structural or nonstructural components or to protect the piping in the event of such impact and where the following size requirements are satisfied:

    1. For Seismic Design Categories D, E or F and values of Ip greater than one, the nominal pipe size shall be 1 inch (25 mm) or less.
    2. For Seismic Design Categories D, E or F, where Ip = 1.0 the nominal pipe size shall be 3 inches (80 mm) or less.

The exceptions above shall not apply to elevator piping.

Modify ASCE 7, Section 13.6.10.1, by adding Section 13.6.10.1.1 as follows:

13.6.10.1.1 Elevators guide rail support. The design of guide rail support-bracket fastenings and the supporting structural framing shall use the weight of the counterweight or maximum weight of the car plus not less than 40 percent of its rated load. The seismic forces shall be assumed to be distributed one third to the top guiding members and two thirds to the bottom guiding members of cars and counterweights, unless other substantiating data are provided. In addition to the requirements of ASCE 7, Section 13.6.10.1, the minimum seismic forces shall be 0.5g acting in any horizontal direction.

Replace ASCE 7, Section 13.6.10.4, as follows:

13.6.10.4 Retainer plates. Retainer plates are required at the top and bottom of the car and counterweight, except where safety devices acceptable to the enforcement agency are provided which meet all requirements of the retainer plates, including full engagement of the machined portion of the rail. The design of the car, cab stabilizers, counterweight guide rails and counter-weight frames for seismic forces shall be based on the following requirements:

  1. The seismic force shall be computed per the requirements of ASCE 7 Section 13.6.10.1. The minimum horizontal acceleration shall be 0.5g for all buildings.
  2. Wp shall equal the weight of the counterweight or the maximum weight of the car plus not less than 40 percent of its rated load.
  3. With the car or counterweight located in the most adverse position, the stress in the rail shall not exceed the limitations specified in these regulations, nor shall the deflection of the rail relative to its supports exceed the deflection listed below:

    RAIL SIZE (weight per foot of length, pounds)WIDTH OF MACHINED SURFACE (inches)ALLOWABLE RAIL DEFLECTION (inches)
    811/40.20
    1111/20.30
    1213/40.40
    15131/320.50
    181/2131/320.50
    221/220.50
    3021/40.50

    For SI: 1 inch = 25 mm, 1 foot = 305 mm, 1 pound = 0.454 kg.

    Note: Deflection limitations are given to maintain a consistent factor of safety against disengagement of retainer plates from the guide rails during an earthquake.

  4. Where guide rails are continuous over supports and rail joints are within 2 feet (610 mm) of their supporting brackets, a simple span may be assumed.
  5. The use of spreader brackets is allowed.
  6. Cab stabilizers and counterweight frames shall be designed to withstand computed lateral load with a minimum horizontal acceleration of 0.5g.

Remove ASCE 7, Sections 16.1.4.1 and 16.1.4.2, and modify Section 16.1.4, by the following:

Maximum scaled base shears used to determine forces and drifts shall not be less than the base shear calculated using the equivalent lateral force procedure of Section 12.8.

Modify ASCE 7, Section 16.2.2, by adding the following:

Requirements of this section shall be deemed to be satisfied for new buildings, using acceptance criteria, in Section 16.2.4.2, by the nonlinear modeling parameters in ASCE 41.

Modify ASCE 7, Section 16.2.3, by adding the following:

Requirements of this section shall be deemed to be satisfied by using load combinations in Sections 12.4.2.3 and 12.4.3.2 with 25 percent of the required live loads.

Modify ASCE 7, Section 16.2.4, by the following:

  1. Where site is located within 3.1 miles (5 km) of an active fault at least seven ground motions shall be analyzed and response parameters shall be based on larger of the average of the maximum response with ground motions applied as follows:

    1. Each of the ground motions shall have their maximum component at the fundamental period aligned in one direction.
    2. Each of the ground motion’s maximum component shall be rotated orthogonal to the previous analysis direction.
  2. Where site is located more than 3.1 miles (5 km) from an active fault at least 10 ground motions shall be analyzed. The ground motions shall be applied such that one-half shall have their maximum component aligned in one direction and the other half aligned in the orthogonal direction. The average of the maximum response of all the analyses shall be used for design.

Replace ASCE 7 exception to Section 16.2.3 by the following:

Where this standard requires the consideration of the load combinations with overstrength factor of Section 12.4.3.2, average demand from MCE analysis obtained from suite of analysis in accordance with Section 16.2.4 shall be used with Immediate Occupancy (IO) acceptance criteria in Section 16.2.4.2.

Modify ASCE 7, Section 16.2.4.2, by the following:

Acceptance criteria for elements subjected to deformation beyond their linear range of response shall be based on ASCE 41 for Immediate Occupancy (IO) at Design Earthquake (DE) and Life Safety (LS) at Maximum Considered Earthquake (MCER).

Modify ASCE 7, Section 17.2.4.7, by adding the following:

The effects of uplift shall be explicitly accounted for in the testing of the isolator units.

Modify ASCE 7, Section 17.4.2, by adding the following:

17.4.2.3 Linear procedures. Linear procedures shall not be used in Seismic Design Category E & F structures.

Modify ASCE 7, Section 17.6, by the following:

17.6.1.1 Minimum seismic force. For the response spectrum and linear response history procedures, Vb and Vs shall not be taken less than those calculated in accordance with Equations 17.5-7 and 17.5-8.

Modify ASCE 7, Section 18.3.1, by replacing the third paragraph with the following:

If the calculated force in an element of the seismic force resisting system does not exceed 1.5 times its nominal strength for the Risk-Targeted Maximum Considered Earthquake (MCER) nor its nominal strength for the design earthquake (DE), the element is permitted to be modeled as linear. For this section, the MCER and DE response shall be based on largest response due to a single ground motion and not the average response of suite of ground motions.

[OSHPD 1 & 4] Modify ASCE 7 by the following:

Scope: For buildings with welded steel moment frames constructed under a permit issued prior to October 25, 1994 post-earthquake verification shall be in accordance with this section.

Verification: After every seismic event that generates ground motions specified in the California Administrative Code, Chapter 6, Section 4.2.0.1 or the damage indicators specified in the California Administrative Code, Chapter 6, Section 4.2.0.2 at a welded steel moment frame building constructed under a permit issued prior to October 25, 1994, the owner shall retain a structural engineer to perform detailed joint evaluations required to meet the following requirements:

  1. A detailed joint evaluation program shall be submitted to the enforcement agency for approval prepared in accordance with the requirements of the California Administrative Code, Chapter 6, Section 4.2.0.3.
  2. Upon approval of the joint evaluation program required by Item 1 above for the joint inspections, a project to perform the joint inspections, detailed in the program, shall be submitted and a building permit shall be obtained by the owner no later than 6 months from the date of occurrence of the seismic event.

    Exception: Where the ground motions at the building site are less than 0.4g, the permit shall be obtained no later than 12 months from the date of occurrence of the seismic event.

  3. A detailed joint evaluation report shall be submitted to the enforcement agency no later than 6 months of obtaining the building permit. The report shall document the findings from the inspections of the joints and include conclusions on the adequacy of the structural system. Where unsafe conditions are discovered, the provisions of Section 116 shall apply.

Where the detailed joint evaluation report is not submitted within the timeframes specified above, the building shall not be issued a building permit for any projects except for those for seismic compliance, maintenance and repair until the detailed joint evaluation work is complete.

[OSHPD 1 & 4] New general acute care hospitals and new building(s) required for general acute care services shall satisfy Operational Nonstructural Performance Level (NPC-5) requirements.

Exception: A new building which is required for general acute care services that is added to an existing general acute care hospital and which has a building area of 4,000 square feet (371 m2) or less, need not satisfy the NPC-5 requirements until the deadline specified in California Administrative Code (Part 1, Title 24 CCR), Chapter 6.

Hospitals and buildings designed and constructed to the provisions of this code for new construction shall be deemed to satisfy Operational Nonstructural Performance Level (NPC-5) requirements when:

  1. The facility has on-site supplies of water and holding tanks for sewage and liquid waste, sufficient to support 72 hours of emergency operations for the hospital or building, which are integrated into the building plumbing systems in accordance with the California Plumbing Code.
  2. An on-site emergency system as defined in the California Electrical Code is incorporated into the building electrical system for critical care areas. Additionally, the system shall provide for radiological service and an onsite fuel supply for 72 hours of acute care operation.

Emergency and standby generators shall not be located below the higher of the Design Flood Elevation (DFE) or Base Flood Elevation (BFE) plus two feet (BFE + 2 ft.) or 500 year flood elevation, whichever is higher, and shall be located at an elevation close to grade for easy accessibility from outside for maintenance.

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