Development of duration-dependent damage-based inelastic response spectra

A simple relationship is proposed in this paper to construct damage-based inelastic response spectra including the effect of ground motion duration that it can be used for damage control in seismic design of structures. This relation is established for three groups of ground motions with short-duration, moderate-duration, and long-duration ranges. To develop the model, the duration effect is included in the cyclic ductility of structures by an energy-based method, and then strength reduction factors are computed based on this modified ductility (named RDs). The strength reduction factors were calculated for 44 stiffness-degrading oscillators having vibration periods between 0.05 and 4.0s, four ultimate ductility capacities, and five damage levels subjected to 296 earthquake records. The results showed that ductility capacity, damage level, and ground motion duration are effective parameters in the energy dissipation of structures, which affect the RDs spectra. The RDs values of short-period oscillators (e.g., low-rise structures) under short-duration records are generally greater than those under moderate-duration and long-duration records. Residual analysis has been made in terms of magnitude and distance to examine the validity of the proposed simple expression. Finally, the introduced RDs spectra were compared with three previously published proposals. Copyright (c) 2016 John Wiley & Sons, Ltd.