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303.3.2 Revise item 2 as follow:1
303.3.2 Compliance with reduced seismic forces. Where seismic evaluation and design is permitted to use reduced seismic forces, the criteria used shall be in accordance with one of the following:
2. Except where these requirements are triggered by Section 503.11, structures or portions of structures that comply with the requirements of the applicable chapter in Appendix A as specified in Items 2.1 through 2.5 and subject to the limitations of the respective Appendix A chapters shall be deemed to comply with this section.
1. So in Ord. 265-19.
303.4 Add the following sections:
303.4 Minimum Lateral Force for Existing Buildings.
303.4.1 General. This section is applicable to existing buildings when invoked by SFEBC Section 503 . This section may be used as a standard for voluntary upgrades.
An existing building or structure which has been brought into compliance with the lateral force resistance requirements of the San Francisco Building Code in effect on or after the dates shown in Table 303.4.1 shall be deemed to comply with this section except when a vertical extension or other alterations are to be made which would increase the mass or reduce the seismic resistance capacity of the building or structure. Where multiple building types apply, the later applicable date shall be used. Where none of the building types apply, compliance shall be at the discretion of the Director. Building type definitions are given in ASCE 41, Table 3-1.
TABLE 303.4.1 – DATES REQUIRED TO DEMONSTRATE BUILDING COMPLIANCE
Date of Compliance
Model Code (for reference)
Wood Frame, wood shear panels (Types W1 & W2)
Wood Frame, wood shear panels (Type W1A)
Floor areas greater than 3,000 ft2 per level
Steel moment-resisting frame (Types S1 & S1a)
Steel concentrically braced frame (Types S2 & S2a)
Steel eccentrically braced frame (Types S2 & S2a)
Buckling-restrained braced frame (Types S2 & S2a)
Light metal frame (Type S3)
Steel frame w/ concrete shear walls (Type S4)
Steel plate shear wall (Type S6)
Reinforced concrete moment-resisting frame (Type C1)
Reinforced concrete shear walls (Types C2 & C2a)
Tilt-up concrete (Types PC1 & PC1a)
Precast concrete frame (Types PC2 & PC2a)
Reinforced masonry (Type RM1)
Reinforced masonry (Type RM2)
Seismic isolation or passive dissipation
303.4.2 Wind forces. Buildings and structures shall be capable of resisting wind forces as prescribed in San Francisco Building Code Section 1609.
303.4.3 Seismic forces. Buildings and structures shall comply with the reduced seismic forces, as defined in Section 303.3.2. The building separation limitations of Section ASCE 7-16 Section 12.12.3 need not be considered.
When upper floors are exempted from compliance by Section 503.11.1, the lateral forces generated by their masses shall be included in the analysis and design of the lateral force resisting systems for the strengthened floor. Such forces may be applied to the floor level immediately above the topmost strengthened floor and distributed in that floor in a manner consistent with the construction and layout of the exempted floor.