Summary and conclusions
A steel-timber hybrid building made of steel moment-resisting frames and prefabricated infill wood shear walls to resist later loads for multi-story buildings has been proposed. This paper presents a seismic performance assessment for these hybrid structures. The performance-based seismic design objectives under the IO, LS, and CP performance levels were discussed and defined. Nine prototype structures with three building height levels (i.e., 3-story, 6-story, and 9- story) and various infill wall configurations were designed. The infill configurations were designed based on the lateral infill-to-frame stiffness ratio, λ. FE models were developed for the steel-timber hybrid structures, and comprehensive nonlinear time-history analyses were conducted to investigate the seismic behavior of the prototype structures. The lateral stiffness ratio, λ, crucially influenced the fundamental period of the structure. Since the structure with large λ adopted stiffer and stronger infill wood shear walls, the period of the prototype structure decreased by 21.6%, on average, when λ increased from 1.0 to 2.0, and the period of the prototype structure decreased further by 15.0% when λ increased from 2.0 to 3.0. The probability of failure, with respect to a specified hazard level, was evaluated on the CDF given the performance criterion. As expected, as λ increased, the shear wall peak displacement decreased. The results demonstrated that the drift targets for the LS performance level did not control the design of the LLRS of the steel-timber hybrid structure. Thus, the performance-based design of the proposed steel-timber hybrid structural system should be focused on sizing the steel and timber members to have sufficient elastic stiffness under the IO performance level and maintaining a reasonable amount of postyielding strength and stiffness under the CP performance level.
