Models for analysis shall be three-dimensional and shall conform to the requirements of the applicable building code. Members shall be designated and modeled as either force-controlled or deformation-controlled in accordance with the applicable building code.
Modeling of member nonlinear behavior, including effective stiffness, expected strength, expected deformation capacity, and hysteresis under force or deformation reversals, shall be substantiated by physical test data, detailed analyses, or other supporting evidence. The provisions given in this appendix shall be deemed to satisfy this requirement.
For deformation-controlled members that are modeled inelastically, degradation in member strength or stiffness shall be included in the numerical models unless it can be demonstrated that the demand is not sufficiently large to produce these effects.
Member initial geometric imperfections shall be included in the numerical model in members where imperfections are required to capture the forces resisted by the member under nonlinear response.
Component modeling shall be based on expected material properties. Expected material strengths shall be as specified in Section A3.2.
Seismic force-resisting systems shall be analyzed as required in Chapters E, F, G, and H. Component-specific and system-specific modeling and analysis shall conform to the requirements in Sections 1.5 through 1.7. The gravity framing system shall be modeled in the nonlinear analysis unless it can be demonstrated to not significantly contribute to the seismic force and deformation demands in the structure. If gravity columns are not explicitly modeled, the leaning column effect of the gravity system shall be modeled.