A Performance-Based Hybrid Force-Displacement Seismic Design Method for Reinforced Concrete Structures

Abstract

A performance-based hybrid force-displacement (HFD) seismic design method is proposed for three types of reinforced concrete structures, i.e., moment resisting frames, frame with infills and wall-frame dual systems. HFD is a force-based method which controls with high accuracy both structural and non-structural deformation limits, since, both limits are input variables for the initiation of the design. This is accomplished by constructing explicit empirical expressions for a behavior (strength reduction) factor, which incorporates target non-structural and structural deformation metrics such as inter-storey drift ratio and member plastic rotation. Use of this factor in conjunction with an elastic acceleration spectrum can produce designs in one-step, by just conducting a strength checking, since the deformation restrictions are automatically satisfied. Those expressions for the behavior factor in terms of target deformation metrics, number of storeys, column to beam strength ratios, beam to column and column-to-wall stiffness ratios, respectively, are derived through extensive parametrical studies involving non-linear dynamic analysis of the above appropriately modeled structures under 100 ground motions scaled for different deformation targets. The proposed HFD method is demonstrated and validated with realistic design examples, which show its advantages over the force-based design method of the European seismic design code, Eurocode 8.