Section 317 Earthquake Evaluation and Design for Retrofit of Existing Buildings
[BSC] The provisions of Sections 317 through 322 establish minimum standards for earthquake evaluation and design for retrofit of existing state-owned structures, including buildings owned by the University of California and the California State University.
[DSA-SS] The provisions of Sections 317 through 323 establish minimum standards for earthquake evaluation and design for the rehabilitation of existing buildings for use as public school buildings under the jurisdiction of the Division of the State Architect—Structural Safety [DSA-SS], refer to Section 184.108.40.206.
The provisions of Section 317 through 323 also establish minimum standards for earthquake evaluation and design for rehabilitation of existing public buildings currently under the jurisdiction of DSA-SS.
[DSA-SS/CC] The provisions of Sections 317 through 323 establish minimum standards for earthquake evaluation and design for the rehabilitation of existing buildings for use as community college buildings under the jurisdiction of the Division of the State Architect—Structural Safety/Community Colleges [DSA-SS/CC], refer to Section 220.127.116.11.
The provisions of Section 317 through 323 also establish minimum standards for earthquake evaluation and design for rehabilitation of existing community college buildings currently under the jurisdiction of DSASS/CC.
All modifications, structurally connected additions and/or repairs to existing structures or portions thereof shall, at a minimum, be designed and constructed to resist the effects of seismic ground motions as provided in this section. The structural system shall be evaluated by a registered design professional and, if not meeting or exceeding the minimum seismic design performance requirements of this section, shall be retrofitted in compliance with these requirements.
Exception: Those structures for which Section 317.3 determines that assessment is not required, or for which Section 317.4 determines that retrofit is not needed, then only the requirements of Section 317.11 apply.
[BSC] For existing state-owned structures including all buildings owned by the University of California and the California State University, the requirements of Section 317 apply whenever the structure is to be retrofitted, repaired or modified and any of the following apply:
- Total construction cost, not including cost of furnishings, fixtures and equipment, or normal maintenance, for the building exceeds 25 percent of the construction cost for the replacement of the existing building. The changes are cumulative for past modifications to the building that occurred after adoption of the 1995 California Building Code and did not require seismic retrofit.
- There are changes in risk category.
- The modification to the structural components increases the seismic forces in or strength requirements of any structural component of the existing structure by more than 10 percent cumulative since the original construction, unless the component has the capacity to resist the increased forces determined in accordance with Section 319. If the building's seismic base shear capacity has been increased since the original construction, the percent change in base shear may be calculated relative to the increased value.
- Structural elements need repair where the damage has reduced the lateral-load-resisting capacity of the structural system by more than 10 percent.
- Changes in live or dead load increase story shear by more than 10 percent.
Following the notations of ASCE 41, the seismic requirements for design and assessment are based upon a prescribed Earthquake Hazard Level (BSE-1N, BSE-2N, BSE-1E, BSE-R or BSE-C), a specified structural performance level (S-1 through S-5) and a nonstructural performance level (N-A through NE). The minimum seismic performance criteria are given in Table 317.5 according to the Building Regulatory Authority and the Risk Category as determined in Chapter 16 of the California Building Code or by the regulatory authority. The building shall be evaluated in accordance with a Tier 3 Systematic Evaluation and Retrofit per ASCE 41 Chapter 6 for both the Level 1 and Level 2 performance levels, and the more restrictive requirements shall apply.
Exception: If the floor area of an addition is greater than the larger of 50 percent of the floor area of the original building or 1,000 square feet (93 m2), then the Table 317.5 entries for BSE-R (or BSE-1E) and BSE-C are replaced by BSE-1N and BSE-2N, respectively.
SEISMIC PERFORMANCE REQUIREMENTS BY BUILDING REGULATORY AUTHORITY AND RISK CATEGORY.
|Building Regulatory Authority||Risk Category||PERFORMANCE CRITERIA|
|Level 1||Level 2|
|State-Owned [BSC]||I, II, III||BSE-R, S-3, N-C||BSE-C, S-5, N-D|
|State-Owned [BSC]||IV||BSE-R, S-2, N-B||BSE-C, S-4, N-D|
|Division of the State Architect - [DSA-SS]||I||BSE-1N, S-3, N-B||BSE-2N, S-5, N-D|
|Division of the State Architect - [DSA-SS]||II, III||BSE-1N, S-2, N-B||BSE-2N, S-4, N-D|
|Division of the State Architect - [DSA-SS]||IV||BSE-1N, S-2, N-A||BSE-2N, S-4, N-D|
|Division of the State Architect - [DSA-SS/CC]||I, II||BSE-1E, S-3, N-C||BSE-2N, S-5, N-D|
|Division of the State Architect - [DSA-SS/CC]||III||BSE-1E, S-3, N-B||BSE-2N, S-5, N-D|
|Division of the State Architect - [DSA-SS/CC]||IV||BSE-1E, S-2, N-B||BSE-2N, S-4, N-D|
- ASCE 41 provides acceptance criteria (e.g., m, rotation) for Immediate Occupancy (S1), Life Safety (S3), and Collapse Prevention (S5), and specifies in Sections 18.104.22.168.1 and 22.214.171.124.1 the method to interpolate values for S-2 and S-4, respectively. For nonstructural components, N-A corresponds to the Operational level, N-B to the Position Retention, N-C to the Life Safety level, N-D to the Hazards Reduced, and N-E to the Not Considered. When evaluating for the Hazards Reduced Nonstructural Performance Level, the requirements need not be greater than what would be required by ASCE 7 nonstructural provisions for new construction.
- Buildings evaluated and retrofitted to meet the requirements for a new building, Chapter 16 of the California Building Code, in accordance with the exception in Section 319.1, are deemed to meet the seismic performance requirements of this section.