San Francisco County Municipal Code Ch. 16 Referenced Standards

No San Francisco Existing Building Code Amendments. Add the following appendices: CALIFORNIA EXISTING BUILDING CODE (CEBC) APPENDICES (CEBC) APPENDIX A CHAPTER A1 SEISMIC STRENGTHENING PROVISIONS FOR UNREINFORCED MASONRY BEARING WALL BUILDINGS No San Francisco Existing Building Code Amendments (CEBC) APPENDIX A CHAPTER A2

EARTHQUAKE HAZARD REDUCTION IN EXISTING REINFORCED CONCRETE AND REINFORCED MASONRY WALL BUILDINGS WITH FLEXIBLE DIAPHRAMS1 No San Francisco Existing Building Code Amendments (CEBC) APPENDIX A CHAPTER A3 PRESCRIPTIVE PROVISIONS FOR SEISMIC STRENGTHENING OF CRIPPLE WALLS AND SILL PLATE ANCHORAGE OF LIGHT, WOOD- FRAME RESIDENTIAL BUILDINGS No San Francisco Existing Building Code Amendments (CEBC) APPENDIX A CHAPTER A4 EARTHQUAKE RISK REDUCTION IN WOOD- FRAME RESIDENTIAL BUILDINGS WITH SOFT, WEAK OR OPEN FRONT WALLS No San Francisco Existing Building Code Amendments (CEBC) APPENDIX A CHAPTER A5 REFERENCED STANDARDS No San Francisco Existing Building Code Amendments

[APPENDIX A CHAPTER A6 SEISMIC RETROFIT PROVISIONS FOR CONCRETE BUILDINGS]1 CODIFICATION NOTE

1. Ord. 70-25 did not mark the Chapter A6 heading for addition. The heading has been included here for reference, with square brackets indicating that it is unofficial. A6.1 Intent. This Chapter A6 establishes seismic retrofit provisions intended to reduce the collapse risk of the most vulnerable Concrete Buildings (CB), as defined in Chapter 5G. A6.2 Definitions In addition to the definitions in San Francisco Building Code Chapter 2 and San Francisco Existing Building Code Chapter 2, the following shall apply for purposes of this Chapter A6: Wall pier. A vertical wall segment within a structural wall, bounded horizontally by two openings or by an opening and an edge, with ratio of horizontal length to wall thickness less than or equal to 6.0, and ratio of clear height to horizontal length greater than 2.0. A6.3 Design Professionals. All evaluations and design intended to comply with this Chapter shall be performed by or under the supervision of appropriately licensed individuals, and all documents submitted for compliance shall be sealed by a California licensed civil or structural engineer. A6.4 Structural engineering criteria A6.4.1 Engineering criteria. For a Concrete Building to comply with this Chapter, the building shall satisfy one of the Engineering Criteria Options per Table A6.4-1, by seismic evaluation or seismic retrofit. Table A6.4-1: Engineering Criteria Options

Option (a) Comply with all of the following:

1. ASCE 41 with a performance objective of Structural Collapse Prevention (S-5) with the BSE-1E earthquake hazard level.
2. For each seismic deficiency in Table A6.4-2, demonstrate that the deficiency is not present, or address it by retrofitting. In a bulletin, the Department shall specify requirements for identifying, evaluating, and retrofitting the seismic deficiencies listed in Table A6.4-2.
3. For all unreinforced masonry elements, ASCE 41 with a performance objective of Nonstructural Life Safety (N C) with the BSE-1E earthquake hazard level. Option (b) Comply with all of the following:
4. ASCE 41 with a performance objective of Structural Collapse Prevention (S-5) with the BSE-2E earthquake hazard level. The BSE-1E earthquake hazard level need not be evaluated, regardless of the Tier of evaluation.
5. For all unreinforced masonry elements, ASCE 41 with a performance objective of Nonstructural Life Safety (N C) with the BSE-1E earthquake hazard level.

Table A6.4-2: Seismic deficiencies to be addressed by Engineering Criteria Option (a)

Weak story: The structure includes one or more stories having lateral strength less than the story above. Lateral-force-resisting-element irregularity: The lateral force-resisting system includes one or more concrete walls or frames that are not continuous to the foundation. Non-ductile moment frame: The main lateral-force-resisting-system includes concrete moment frames that do not satisfy strong-column- weak-beam requirements or that have shear-governed columns or beams. Shear-governed concrete column or wall pier: The structure includes one or more concrete columns or wall piers that are shear-governed and susceptible to failure resulting in loss of gravity load support. Punching shear in concrete slab: One or more concrete floor or roof slabs are supported by one or more columns without beams framing into the column and is susceptible to loss of gravity load support following punching shear failure. Weak connection of concrete wall to flexible diaphragm: The structure includes one or more concrete walls connected to one or more flexible diaphragms, where the wall is not adequately anchored to the diaphragm. Inadequate length of bearing connection: One or more concrete beams or slabs are supported by a bearing connection with short bearing length.

A6.4.2 Building separation. The building separation limitations of Section 7.2.13 of ASCE 41 need not be considered.

A6.4.3 Liquefaction or landslide risk. If the building is located in a zone of high or very high risk of soil liquefaction or landslide, as indicated by the current State of California Seismic Hazard Zones Map for San Francisco, the Owner’s Engineer shall so notify the Owner in writing. Aside from such notification, soil liquefaction, lateral spreading, and landslide are not required to be addressed in the seismic evaluation or retrofit design. This Chapter does not exempt the building from the requirements of the Slope and Seismic Hazard Zone Protection Act (San Francisco Building Code 106A.4.1.4) where applicable. A6.4.4 Other retrofit triggers. If the project involves a Substantial Structural Alteration as defined in Section 503.11 or Non-structural Alteration as defined in Section 503.11.1, the building shall meet the more restrictive of the provisions of this Chapter or those of Section 304.4 (Minimum lateral force for existing buildings). A6.4.5 Masonry Infill. For Concrete Buildings with masonry infill, the seismic evaluation and retrofitting shall account for the effect of the infill considering ASCE 41 requirements, and for Tier 2 and Tier 3 evaluations shall take into account: • The peak strength that the infill can achieve. • The potential for strength degradation of the infill. • The potential for a weak story or story concentration of deformation, because of the locations of infill in the building, or because of potential concentrations of damage to infill. • Plan torsion effects because of the location of infill in the building, or because of potential concentrations of damage to infill.