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Energy based evaluation of RC frame structures

Azizi, Mahyar
Nowadays, earthquake and structural engineers perceive that conventional seismic design method, which is based on force and strength, is not an adequate way of designing structures under ground motions. The reason is that the conventional seismic design method does not pay enough attention to inelastic displacements, plastic behavior of structures and duration of seismic motion. At the present time, there are new and popular alternatives to the force-based approach like displacement-based method, in which the aforementioned issues are mostly handled. The energy-based method is another convenient tool to study the performance of structures under seismic action and probably the best way to include the duration of ground motion within the analysis. In the energy-based approach, the energy input to the structure should be dissipated through inelastic action and damping. The inelastic energy dissipation mechanism is called as hysteretic energy. It is an important challenge to obtain the story-wise and component-wise distribution of the total hysteretic energy within the building in order to develop the energy-based design and analysis tools. Such studies have been conducted for steel frames in previous studies; however the distribution of hysteretic energy among the reinforced concrete (RC) beams and columns has not been studied extensively. Accordingly, this study is focused on the story-wise and component-wise distribution of hysteretic energy in RC moment-resisting frames. For this purpose, RC frames with a different number of stories and bays are designed according to the 2018 Turkish Seismic Design Code. Then the designed frames are modeled with lumped plasticity model that introduces the inelasticity at the ends of the beam and column members. The developed models are subjected to a set of strong ground motion records and the distributions of hysteretic energy for each frame and analysis are obtained. The results indicate that it is possible to set up some rules for the hysteretic energy distribution in RC frames that can be used in energy-based design and analysis procedures.