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FIGURE 2.1
SOIL PROFILE TYPES AND SITE COEFFICIENTS
SOIL
PROFILE
TYPE
PROFILE WITH SITE
COEFFICIENT, S
S1 Rock of any characteristic, either shalelike or crystalline in nature. Such material may be characterized by a shear wave velocity greater than 2,500 feet per second or by other appropriate means of classification. 1.0
or
Stiff soil conditions where the soil depth is less than 200 feet and the soil types overlying rock are stable deposits of sands, gravels or stiff clays.
S2 Deep cohesionless or stiff clay conditions, including sites where the soil depth exceeds 200 feet and the soil types overlying rock are stable deposits of sands, gravels or stiff clays. 1.2
S3 Soft- to medium-stiff clays and sands characterized by 30 feet or more of soft- to medium-stiff clays with or without intervening layers of sand or other cohesionless soils. 1.5
S4 More than 70 feet of soft clays or silts characterized by a shear wave velocity less than 400 feet per second. 2.0
FIGURE 2.1a—
EFFECTIVE PEAK ACCELERATION COEFFICIENT (Aa) AND EFFECTIVE PEAK VELOCITY COEFFICIENT (Av) FOR CALIFORNIA
No.CountyEPA AaEPV Av
1Alameda0.400.40
2Alpine0.200.20
3Amador0.200.20
4Butte0.200.20
5Calaveras0.200.20
6Colusa0.200.30
7Contra Costa0.400.40
8Del Norte0.200.20
9El Dorado0.200.20
10Fresno0.400.40
11Glenn0.200.20
12Humboldt0.200.30
13Imperial0.400.40
14Inyo0.400.40
15Kern0.400.40
16Kings0.400.40
17Lake0.300.30
18Lassen0.200.20
19Los Angeles0.400.40
20Madera0.200.30
21Marin0.400.40
22Mariposa0.200.20
23Mendocino0.400.40
24Merced0.400.40
25Modoc0.200.20
26Mono0.400.40
27Monterey0.400.40
28Napa0.400.40
29Nevada0.200.20
30Orange0.400.40
31Placer0.200.20
32Plumas0.200.20
33Riverside0.400.40
34Sacramento0.200.30
35San Benito0.400.40
36San Bernardino0.400.40
37San Diego0.400.40
38San Francisco0.400.40
39San Joaquin0.300.30
40San Luis Obispo0.400.40
41San Mateo0.400.40
42Santa Barbara0.400.40
43Santa Clara0.400.40
44Santa Cruz0.400.40
45Shasta0.200.20
46Sierra0.200.20
47Siskiyou0.200.20
48Solano0.400.40
49Sonoma0.400.40
50Stanislaus0.400.40
51Sutter0.200.20
52Tehama0.200.20
53Trinity0.200.30
54Tulare0.400.40
55Tuolumne0.200.20
56Ventura0.400.40
57Yolo0.200.30
58Yuba0.200.20
2.1.1 Site Visit and Evaluation
  1. The evaluator shall visit the building to observe and record the type, nature and physical condition of the structure.
  2. The evaluator shall review an Engineering Geological Report on site geologic and seismic conditions. The report shall be prepared in accordance with Title 24, Section 1634A of 1995 California Building Code (CBC) or equivalent provision in later version of the CBC.
    Exceptions:
    1. Reports are not required for one-story, wood-frame and light steel-frame buildings of Type II or Type V construction and 4,000 square feet or less in floor area;
    2. A previous report for a specific site may be resubmitted, provided that a reevaluation is made and the report is found by the Office to be currently appropriate.
    3. Establish the following site and soil parameters:
      1. The value of the effective peak acceleration coefficient (Aa) from Figure 2.1 and 2.1a;
      2. The value of the effective peak velocity-related acceleration coefficient (Av) from Figure 2.1 and 2.1a;
      3. The soil profile type (S1, S2, S3 or S4) derived from the geotechnical report or from Table 2.1;
      4. The site coefficient, (S), from Table 2.1; and
      5. The ground motion parameters and near field effects in strong ground shaking required for the evaluation of welded steel moment frame structures in accordance with Sections 4.2.0.1, 4.2.0.2 and 4.2.10.
    4. Assemble building design data including:
      1. Construction drawings, specifications and calculations for the original building (Note: when reviewing and making use of existing analyses and structural member checks, the evaluator shall assess and report the basis of the earlier work);
      2. All drawings, specifications and calculations for remodeling work; and
      3. Material tests and inspection reports for nonconforming buildings. If the original drawings are available, but material test and inspection reports are not available, perform the testing program as specified in Section 2.1.2.2.
      If structural drawings are not available, the site visit and evaluation shall be performed as described in Section 2.1.1.5, and structural data shall be collected using the procedures in Sections 2.1.2.1 and 2.1.2.2.
    5. During the site visit, the evaluator shall:
      1. Verify existing data;
      2. Develop other needed data (e.g., measure and sketch building as outlined in Section 2.1.2);
      3. Verify the vertical and lateral systems;
      4. Check the condition of the building; and
      5. Identify special conditions, anomalies and oddities.
    6. Review other data available such as assessments of building performance following past earthquakes.
    7. Prepare a summary of the data using an OSHPD- approved format.
    8. Perform the evaluation using the procedures in Sections 2.2 through 2.5.
    9. Prepare a report of the findings of the evaluation using an OSHPD-approved format.
2.1.2 Data Collection
Building information pertinent to a structure's seismic performance, including condition, configuration, detailing, material strengths and foundation type, shall be obtained in accordance with this section, and documented on drawings and/or sketches that shall be included with the structural calculations.
Exception: Materials testing is not required for reclassification by the collapse probability assessment option as permitted by Section 1.4.5.1.2, where nonavailability of materials test is identified as a deficiency in accordance with Section 1.8.2.2(b).
2.1.2.1 Building Characteristics
Characteristics of the building relevant to its seismic performance shall be obtained for use in the building evaluation. This shall include current information on the building's condition, configuration, material strengths, detailing and foundation type. This data shall be obtained from:
  1. Review of construction documents;
  2. Destructive and nondestructive testing and examination of selected building components; and
  3. Field observation of exposed conditions to verify that field conditions substantially match the construction documents in accordance with data collection requirements in the California Existing Building Code Section 303A.3.5.3, or equivalent provisions in later editions of the CEBC.
The characteristics of the building shall be established, including identification of the gravity- and lateral-load-carrying systems. The effective lateral-load carrying system may include structural and nonstructural elements that will participate in providing lateral resistance, although these elements may not have intended to provide lateral resistance. The load path shall be identified, taking into account the effects of any modifications, alterations or additions.
The owner or the owner's authorized agent shall submit the following to the office for review and approval:
  1. Complete set of construction documents.
  2. Field test report(s) in accordance with Section 2.1.2.2.
  3. Field observation report, which shall verify that field conditions substantially match the construction documents.
2.1.2.1.1 Nonconforming Buildings Without Construction Documents
Where the available construction documents do not provide sufficient detail to characterize the structure, the evaluation may be based on field surveys, summarized in as-built drawings. These drawings must depict building dimensions, component sizes, reinforcing information (for concrete and masonry elements), connection details, footing information, and the proximity of neighboring structures. All parts of the building that may contribute to the seismic resistance or that may be affected by the seismic response of the structure must be identified. The field survey shall establish the physical existence of the structural members, and identify critical load bearing members, transfer mechanisms, and connections. The survey shall include information on the structural elements and connector materials and details. Performing the field survey will entail removal of fireproofing or concrete encasement at critical locations to permit direct visual inspection and measurement of elements and connections. Nondestructive techniques such as radiographic, electromagnetic and other methods may be used to supplement destructive techniques.
  1. Steel elements. Steel elements shall be classified by structural member type (e.g., rolled or build-up, material grade, and general properties). The survey shall note the presence of degradation or indications of plastic deformation, integrity of surface coatings, and signs of any past movement. For degraded elements, the lost material thickness and reduction of cross-sectional area and moment of inertia shall be determined. Visual inspection of welds shall be per American Welding Society D1.1, "Structural Welding Code-Steel." Structural bolts shall be verified to be in proper configuration and tightened as required in the AISC Steel Construction Manual. Rivets shall also be verified to be in proper configuration and in full contact, with "hammer sounding" conducted on random rivets to ensure they are functional. Nondestructive testing methods, such as dye penetrant and magnetic particle testing, acoustic emission, radiography and ultrasound shall be used when visual inspection identifies degradation or when a particular element or connection is critical to seismic resistance and requires further verification. For buildings in which archaic cast and wrought irons are employed, additional investigations to confirm ductility and impact resistance shall be conducted.
  2. Concrete elements. The configuration and dimensions of primary and secondary structural elements shall be established. The configuration and condition of reinforcing steel shall be assessed, through removal of concrete cover and direct visual inspection, and through nondestructive inspection using electromagnetic, radio-graphic and other methods. Critical parameters of the reinforcing system, such as lap splice length, presence of hooks, development within concrete, degree of corrosion and integrity of the construction shall be established in sufficient detail to perform the structural evaluation.
  3. Masonry elements. The configuration and dimensions of masonry elements shall be established. The configuration and condition of reinforcing-steel shall be assessed, through removal of masonry cover and direct visual inspection, and through nondestructive inspection using electromagnetic, radiographic and other methods. Critical parameters of the reinforcing system, such as lap splice length, presence of hooks, development within concrete, degree of corrosion and integrity of the construction shall be established in sufficient detail to perform the structural evaluation.
  4. Wood elements. The configuration and dimensions of wood elements; the connections between wood elements; and the connections between wood and other structural components or elements such as concrete or masonry walls shall be established. The configuration and condition of wood members, including size, type, grade, condition and quality shall be assessed, through removal of finish materials, and examination of unfinished areas such as attics, crawl spaces and basements. Critical connections and elements shall be visually inspected, using invasive procedures or removal of finishes where necessary. For shear walls, select locations shall be exposed to allow evaluation of sheathing material, nail size, spacing and installation (e.g., overdriven or nails that miss or split the framing members). The base connections of shear resisting elements shall be inspected and evaluated for their adequacy to connect the base of the structure to the foundation or structure below.
  5. Foundation elements. In the absence of dependable construction drawings, determination of the size and detailing of the foundation system requires invasive procedures. The evaluator shall select representative footings for exposure to establish footing size and depth. Conservative assumptions regarding the reinforcement may be made considering code requirements and local practice at the time of the design. In the absence of evidence to the contrary, it may be assumed that the foundation elements were adequately designed to resist actual gravity loads to which the building has been subjected.
2.1.2.2 Material Properties
The building evaluation shall be based on the strength and deformation properties of the existing materials and components. The strength of existing components shall be calculated using data on their configuration, obtained from the original construction documents, supplemented by field observations and the test values of material properties. Where such effects may have a deleterious effect on component or structural behavior, allowances shall be made for the likely effects of strain hardening or degradation. Test values may be obtained from samples extracted from the structure, or from original materials and compliance certificates. The Office will determine the adequacy of the test results based upon the approved material testing program.
The materials testing program shall require approval by the Office prior to testing. Prior to performing destructive materials test and nondestructive tests requiring modification to existing conditions, the owner or the owner's authorized agent shall obtain a building permit.
The materials testing shall be in accordance with the California Existing Building Code Section 303A.3.5.3, or equivalent provisions in later editions of the CEBC.
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