UpCodes logo
Go To Full Code Chapter
Where required, seismic evaluation or design shall be based on the procedures and criteria in this section, regardless of which compliance method is used.
[BS] 304.3.1 Compliance With Full 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 International Building Code. Where the existing seismic force-resisting system is a type that can be designated as "Ordinary," values of R, Ω0 and Cd used for analysis in accordance with Chapter 16 of the International Building Code shall be those specified for structural systems classified as "Ordinary" in accordance with Table 12.2-1 of ASCE 7, unless it can be 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 304.3.1 for the applicable risk category.
PERFORMANCE OBJECTIVES FOR USE IN ASCE 41 FOR COMPLIANCE WITH FULL SEISMIC FORCES
RISK CATEGORY (Based on IBC 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 (S-5)
II Life Safety (S-3) Collapse Prevention (S-5)
III Damage Control (S-2) Limited Safety (S-4)
IV Immediate Occupancy (S-1) Life Safety (S-3)
[BS] 304.3.2 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:
  1. The International Building Code using 75 percent of the prescribed forces. Values of R, Ω0 and Cd used for analysis shall be as specified in Section 304.3.1 of this code.
  2. Structures or portions of structures that comply with the requirements of the applicable chapter in Appendix A as specified in Items 2.1 through 2.4 and subject to the limitations of the respective Appendix A chapters 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 Appendix Chapter A1.
    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 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 Chapter A3.
    2.4.  Seismic evaluation and design of soft, weak or open-front wall conditions in multiple-unit residential buildings of wood construction in Risk Category I or II are permitted to be based on the procedures specified in Chapter A4.
  3. ASCE 41, using the performance objective in Table 304.3.2 for the applicable risk category.
PERFORMANCE OBJECTIVES FOR USE IN ASCE 41 FOR COMPLIANCE WITH REDUCED SEISMIC FORCES
RISK CATEGORY (Based on IBC 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
  1. 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.
  2. 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.
  3. 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.

Related Code Sections

405.2.3.1 Repairs, Evaluation
The building shall be evaluated by a registered design professional, and the evaluation findings shall be submitted to the code official. The ...