Constant-ductility-based energy factor demands of oscillators with modified Clough hysteretic model

This study focuses on the energy factor demand of oscillators with the modified Clough hysteretic model subjected to pulse-like near-fault ground motions. First, the definition of the energy factor demand of modified-Clough oscillators was clarified. Then, oscillators covering a reasonable range of nonlinear parameters and dynamic properties were analysed with a constant-ductility-based method, and a ground motion database characterising pulse-like near-fault ground earthquake motions was used as seismic excitations. The influence of the hysteretic quantities on the energy factor demand of the modified-Clough oscillators was discussed based on the statistical results. Comparison between the energy factor demand from the analysis database and the counterparts computed based on the widely used Newmark-Hall model was made. Recognising the limitations of the current design model, an alternative design equation for estimating the mean energy factor demand of oscillators with the modified Clough hysteretic model was proposed using nonlinear regression analyses. The improved accuracy of the developed model was demonstrated. The research findings of this work provide a basis for energy-balance-based seismic design of structures whose hysteretic force-displacement response can be idealised with the modified-Clough model.