Seismic Performance Assessment of Wood Light-Frame Shearwalls Using the Performance-Based Unified Procedure

This study examines the seismic force modification factors related to overstrength and ductility of wood light-frame shearwalls. Several archetypes were developed to meet different design criteria. Nonlinear static procedure, nonlinear time-history analysis, and nonlinear incremental dynamic analysis were performed. The numerical analyses were based on 2D representations of the designed archetypes. The nonlinear static analysis results revealed an overstrength factor of 2.2, which is greater than the current value of 1.7 for wood light-frame shearwalls. The findings also indicated that existing design requirements for hold-downs and the overcapacity requirement for the first and second stories may not always ensure satisfactory performance. The archetype detailed screening step proved valuable as a preliminary assessment prior to the incremental dynamic analysis in identifying critical archetypes. The results of the performance margin ratios indicated that the archetypes marginally met the life safety performance level. Overall, this study suggests a need for potential adjustments in design standards and considerations for a more comprehensive evaluation of the seismic performance of wood light-frame shearwalls. This study also found that adhering to design requirements related to certain irregularities decreased the probability of collapse in those archetypes.