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Article 6. Repairs to Existing Buildings and Structures
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Add a new Subsection 405.2.7 to Chapter 4 Section 405 of the California Existing Building Code.

405.2.7 Seismic Evaluation and Design Procedures for Repairs. The seismic evaluation and design shall be based on the procedures specified in the California Building Code or ASCE 41 Seismic Evaluation and Retrofit of Existing Buildings. The procedures contained in Appendix A Chapters A1, A3 and A4 of the California Existing Building Code and Appendix A Chapter A2 of the International Existing Building Code shall be permitted to be used as specified in Section 405.2.7.2.

405.2.7.1 Compliance with CBC level seismic forces. Where compliance requires the use of full seismic forces, the criteria shall be in accordance with one of the following:

1.    One-hundred percent of the values in the California Building Code. Where the existing seismic force-resisting system is a type that can be designated as "Ordinary," the values of R, Ωo, and Cd used for analysis in accordance with Chapter 16 of the California Building Code shall be those specified for structural systems classified as "Ordinary" in accordance with Table 12.2-1 of ASCE 7, unless it is demonstrated that the structural system will provide performance equivalent to that of a "Detailed," "Intermediate" or "Special" system.

2.    ASCE 41, using a Tier 3 procedure and the two-level performance objective in Table 405.2.7.1.

Table 405.2.7.1. PERFORMANCE OBJECTIVES FOR USE IN ASCE 41 FOR COMPLIANCE WITH FULL SEISMIC FORCES

RISK CATEGORY (Based on CBC Table 1604.5)

STRUCTURAL PERFORMANCE LEVEL FOR USE WITH BSE-1N EARTHQUAKE HAZARD LEVEL

STRUCTURAL PERFORMANCE LEVEL FOR USE WITH BSE-2N EARTHQUAKE HAZARD LEVEL

I

Life Safety (S-3)

Collapse Prevention (CP)

II

Life Safety (S-3)

Collapse Prevention (CP)

III

Damage Control (S-2)

Limited Safety (S-4)

IV

Immediate Occupancy (S-1)

Life Safety (S-3)

405.2.7.2 Compliance with reduced CBC level seismic forces. Where seismic evaluation and design is permitted to meet reduced seismic forces, the criteria used shall be in accordance with one of the following:

1.    The California Building Code using 75 percent of the prescribed forces. Values of R, Ωo, and Cd used for analysis shall be as specified in Section 405.2.7.1 Item 1.

2.    Structures or portions of structures that comply with the requirements of the applicable chapter in Appendix A of the California Existing Building Code (CEBC) or Appendix A of the International Existing Building Code (IEBC) as specified in Items 2.1 through 2.4 below shall be deemed to comply with this section.

2.1. The seismic evaluation and design of unreinforced masonry bearing wall buildings in Risk Category I or II are permitted to be based on the procedures specified in CEBC Appendix A Chapter A1, provided the design is no less stringent than required in Berkeley Municipal Code Section 19.38.130.

2.2. Seismic evaluation and design of the wall anchorage system in reinforced concrete and reinforced masonry wall buildings with flexible diaphragms in Risk Category I or II are permitted to be based on the procedures specified in IEBC Appendix A Chapter A2.

2.3. Seismic evaluation and design of cripple walls and sill plate anchorage in residential buildings of light-frame wood construction in Risk Category I or II are permitted to be based on the procedures specified in CEBC Appendix A Chapter A3.

2.4. Seismic evaluation and design of soft, weak, or open-front wall conditions in multiunit residential buildings of wood construction in Risk Category I or II are permitted to be based on the procedures specified in CEBC Appendix A Chapter A4.

3.    ASCE 41, using the performance objective in Table 405.2.7.2 for the applicable risk category. The design spectral response acceleration parameters Sxs and Sx1 specified in ASCE 41 shall not be taken less than 75 percent of the respective design spectral response acceleration parameters SDS and SD1 defined by the California Building Code and its reference standards.

Table 405.2.7.2. PERFORMANCE OBJECTIVES FOR USE IN ASCE 41 FOR COMPLIANCE WITH REDUCED SEISMIC FORCES

RISK CATEGORY (Based on CBC Table 1604.5)

STRUCTURAL PERFORMANCE LEVEL FOR USE WITH BSE-1E EARTHQUAKE HAZARD LEVEL

STRUCTURAL PERFORMANCE LEVEL FOR USE WITH BSE-2E EARTHQUAKE HAZARD LEVEL

I

Life Safety (S-3). See Note a

Collapse Prevention (S-5)

II

Life Safety (S-3). See Note a

Collapse Prevention (S-5)

III

Damage Control (S-2). See Note a

Limited Safety (S-4). See Note b

IV

Immediate Occupancy (S-1)

Life Safety (S-3). See Note c

a.    For Risk Categories I, II, and III, the Tier 1 and Tier 2 procedures need not be considered for the BSE-1E earthquake hazard level.

b.    For Risk Category III, the Tier 1 screening checklists shall be based on the Collapse Prevention, except that checklist statements using the Quick Check provisions shall be based on MS-factors that are the average of the values for Collapse Prevention and Life Safety.

c.    For Risk Category IV, the Tier 1 screening checklists shall be based on Collapse Prevention, except that checklist statements using the Quick Check provisions shall be based on MS-factors for Life Safety.

Table 405.2.7.3. REFERENCED STANDARDS

Standard Reference Number

Title

Referenced in Code Section Number

ASCE 41-17

Seismic Evaluation and Retrofit of Existing Buildings

405.2.7
Table 405.2.7.1
405.2.7.2
Table 405.2.7.2

(Ord. 7839-NS § 1, 2022)