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3403.6.1.1.3 Reduced CBC level seismic forces. When seismic forces are permitted to meet <br />reduced building code levels, they shall be one of the following: <br />75 percent of the forces prescribed in the building code. The R factor used for analysis in <br />accordance with Chapter l 6 of the building code shall be the R factor as specified in <br />Section 3403.6.1.1.2. <br />2. In accordance with the applicable chapters in Appendix A of the International Existing <br />Building Code as specified in Items 2.1 through 2.5 below. Structures or portions of <br />structures that comply with the requirements of the applicable chapter in Appendix A <br />shall be deemed to comply with the requirements for reduced building code force levels. <br />2.1. The seismic evaluation and design of unreinforced masonry bearing wall buildings <br />in Occupancy Category I or II are permitted to be based on the procedures specified <br />in Appendix Chapter A 1. <br />2.2. Seismic evaluation and design of the wall anchorage system in reinforced concrete <br />and reinforced masonry wall buildings with flexible diaphragms in Occupancy <br />Category I or II are permitted to be based on the procedures specified in Appendix <br />Chapter A2. <br />2.3. Seismic evaluation and design of cripple walls and sill plate anchorage in residential <br />buildings of light-frame wood construction in Occupancy Category I or II are <br />permitted to be based on the procedures specified in Appendix Chapter A3. <br />2.4. Seismic evaluation and design of soft, weak, or open-front wall conditions in <br />multiunit residential buildings of wood construction in Occupancy Category I or II <br />are permitted to be based on the procedures specified in Appendix Chapter A4. <br />2.5. Seismic evaluation and design of concrete buildings and concrete with masonry infill <br />buildings in all Occupancy Categories are permitted to be based on the procedures <br />specified in Appendix Chapter A5. <br />3. In accordance with ASCE 31 based on the applicable performance level as shown in <br />Table 3403.6.1.1.2. <br />4. Those associated with the BSE-I Earthquake Hazard Level defined in ASCE 4I and the <br />performance level as shown in Table 3403.6.1.1.2. Where ASCE 41 is used, the design <br />spectral response acceleration parameters SXS and Sx~ shall not be taken less than 75 <br />percent of the respective design seismic coefficients 2.SCa and C,, as defined in Tables <br />16-Q and 16-R of the Uniform Building Code. <br />3403.6.1.2 Wind Design. Wind design of existing buildings shall be based on the procedures <br />specified in the building code. <br />3403.6.2 Repairs to damaged buildings. Repairs to damaged buildings shall comply with this <br />section. <br />3403.6.2.1 Unsafe conditions. Regardless of the extent of structural damage, unsafe_conditions <br />shall be eliminated. <br />3403.6.2.2 Substantial structural damage to vertical elements of the lateral-force-resisting <br />system. A building that has sustained substantial structural damage to the vertical elements of its <br />26 <br />