Evaluation of Seismic Deflection Amplification Factor for Buildings Utilizing Cold-Formed Steel-Framed Shear Walls

The seismic deflection amplification factor for a series of archetype buildings utilizing cold-formed steel-framed shear walls was investigated. A total of 118 archetype buildings were considered, of which 83 employed cold-formed steel-framed shear walls with steel sheet sheathing, and 35 employed wood structural panel sheathing. Using nonlinear equivalent single-degree-of-freedom (SDOF) models, nonlinear time-history analyses for the 118 archetype buildings subjected to the 44 FEMA P-695 earthquakes were conducted. In these SDOF models, the actual response of shear walls obtained from experimental studies was used to define the nonlinear material parameters. The AISI S400 deflection expression was evaluated using experimental data, and numerically predicted deflection amplification factors were calculated and compared against that recommended in current practice. The results show that current practice may overestimate expected deflections. To address this issue, and to simplify design, a linearization of the AISI S400 deflection expression is recommended. With appropriate choice of the force level, the linearized AISI S400 deflection expression leads to acceptable drift predictions with the currently employed deflection amplification factor.