Energy-Based Seismic Design Method Of Chevron Concentrically Braced Steel Frame Under Far-Field Earthquake

The current seismic design method based on strength is used in Code for Seismic Design of Buildings,which ignores the accumulative damage of structure by cyclic effect of ground motion,also cannot guarantee the expected failure mode of structure under rare earthquake.However,the energy-based seismic design method,considering the effects of force,displacement,duration etc.,which can reflect the cyclic plastic deformation and the accumulative hysteretic energy of structure,is promising in the development of performance-based seismic design method.Structure damage is closely related to the cyclic effect of far-field ground motion.An energy-based seismic design method of chevron concentrically braced steel frame based on normalized hysteretic energy spectrum and accumulative ductility spectrum under far-field earthquake was proposed.The specific design procedures of this method were introduced,the calculating formulas of accumulative hysteretic energy and the design methods for the sections of structural members were also proposed.Ten-story and fifteen-story chevron concentrically braced steel frames with three spans were designed by using this method.A total of 15 far-field ground motion records were selected,and the seismic behavior of the two structures was evaluated by pushover and nonlinear time history analysis.The analytical results show that the two structures exhibit the ideal yield mechanism,the interstory drifts of the two structures can meet the requirements of Code for Seismic Design of Buildings under frequent earthquake,moderate earthquake and rare earthquake level,and the distribution of deformation and accumulative hysteretic energy over the height of the two structures is uniform.The reliability of this energy-based seismic design method is verified.