Evaluation of seismic collapse resistance of reinforced concrete frames designed with nonlinear viscous dampers

Abstract

In earthquake engineering, damping devices are commonly used to enhance the energy dissipation capacity of structures and help control the structural dynamic response under seismic excitation. In the design of building structures with integration of seismic dampers, the section sizes of structural components and the amount of reinforcement may be reduced so that the seismic performance of the structure remains comparable to a conventional design without dampers under design seismic actions. Understandably such changes in the design scheme can lead to some different structural behavior under different levels of seismic actions; however there is little information in the literature on this subject, particularly with regard to the capacities of the structures in resisting collapse in the event of worst case scenario earthquakes. This paper presents an evaluation of the collapse resistance capacities of structures designed with integration of seismic dampers. A numerical model for the collapse resistance analysis of reinforced concrete (RC) frame structures is firstly explored. To ensure that the model is capable of capturing the collapse resistance capacity, a material state based elemental failure criterion is adopted and the adequacy of this is verified against relevant experimental data. The numerical model is then employed to evaluate the collapse resistance performances of RC frames designed for different earthquake intensities with and without nonlinear viscous dampers via collapse fragility analysis. The results show that when designed for low to moderate seismic intensities, the frame structures designed with integrated dampers (DDF structures) exhibit slightly higher collapse resistance capacity as compared with the conventional design without damper (CDF structures). However, when designed for high seismic hazard levels, the DDF structures tend to have a markedly lower collapse resistance capacity than their conventional counterparts. A remedial scheme is proposed to improve the collapse resistance performances of frames designed with consideration of dampers in high seismic hazard applications, and the effectiveness of such a scheme is further evaluated through the fragility analysis.