2009 ORD O-01-09 - Laserfiche WebLink

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 3403.5.1.1.1 Evaluation and design procedures. The seismic evaluation and design shall be based on the procedures specified in the building code, ASCE 31 Seismic Evaluation of Existing Buildings (for evaluation only) or ASCE 41 Seismic Rehabilitation of Existing Buildings. The procedures contained in Appendix A of the International Existing Building Code shall be permitted to be used as specified in Section 3403.5.1.1.3. 3403.5.1.1.2 CBC level seismic forces. When seismic forces are required to meet the building code level, they shall be one of the following: 1. 100 percent of the values in the building code. The R factor used for analysis in accordance with Chapter 16 of the building code shall be the R factor specified for structural systems classified as "Ordinary' unless it can be demonstrated that the structural system satisfies the proportioning and detailing requirements for systems classified as "Intermediate" or "Special". 2. Forces corresponding to BSE -1 and BSE -2 Earthquake Hazard Levels defined in ASCE 41. Where ASCE 41 is used, the corresponding performance levels shall be those shown in Table 3403.5.1.1.2. TABLE 3403.5.1.1.2 ASCE 41 and ASCE 31 PERFORMANCE LEVELS OCCUPANCY CATEGORY PERFORMANCE LEVEL PERFORMANCE LEVEL FOR (BASED ON IBC FOR USE WITH ASCE 31 USE WITH ASCE 41 BSE -2 TABLE 1604.5) AND WITH ASCE 41 EARTHQUAKE HAZARD BSE -1 EARTHQUAKE LEVEL HAZARD LEVEL I Life Safety (LS) Collapse Prevention (CP) II Life Safety (LS) Collapse Prevention (CP) III Note (a) Note (a) IV Immediate Occupancy 10 Life Safe LS a. Performance Levels for Occupancy Category III shall be taken as halfway between the performance levels specified for Occupancy Category II and Occupancy Category IV. 3403.5.1.1.3 Reduced CBC level seismic forces. When seismic forces are permitted to meet reduced building code levels, they shall be one of the following: 1.75 percent of the forces prescribed in the building code. The R factor used for analysis in accordance with Chapter 16 of the building code shall be the R factor as specified in Section 3403.5.1.1.2. 2. In accordance with the applicable chapters in Appendix A of the International Existing Building Code as specified in Items 2.1 through 2.5 below. Structures or portions of structures that complywith the requirements of the applicable chapter in Appendix A shall be deemed to comply with the requirements for reduced building code force levels. 2.1. The seismic evaluation and design of unreinforced masonry bearing wall buildings in Occupancy Category I or II are permitted to be based on the procedures specified in Appendix Chapter Al. 2.2. Seismic evaluation and design of the wall anchorage system in reinforced concrete and reinforced masonry wall buildings with flexible diaphragms in Occupancy Category I or II are permitted to be based on the procedures specified in Appendix Chapter A2. 2.3. Seismic evaluation and design of cripple walls and sill plate anchorage in residential buildings of light -frame wood construction in Occupancy Category I or II are permitted to be based on the procedures specified in Appendix Chapter A3. 2.4. Seismic evaluation and design of soft, weak, or open -front wall conditions in multiunit residential buildings of wood construction in Occupancy Category I or II are permitted to be based on the procedures specified in Appendix Chapter A4. 2.5. Seismic evaluation and design of concrete buildings and concrete with masonry infill buildings in all Occupancy Categories are permitted to be based on the procedures specified