Analysis of influence of dynamic characteristics of structures on strength reduction factors

The strength reduction factors are not only the key factors in determining seismic action for force-based seismic design, but also the key parameters to derivate the inelastic response spectra for performance-based seismic design. A statistical study is performed of strength reduction factors computed for SDOF systems with various dynamic characteristics when subjected to a large number of earthquake accelerations. The influence of period of structures, displacement ductility, damping and hysteretic model et al. on strength reduction factors are investigated. It is concluded that the strength reduction factors are primarily influenced by displacement ductility and the period of structures. The damping effect increases with the increasing of displacement ductility and the decreasing of period. And the damping effect should cause more attention for strength reduction factors while displacement ductility over 3 during the short-period range. As to effects of the hysteretic model it is almost the same throughout the whole periods range except those in extreme short period range. The hysteretic model effect cannot be neglected in the whole period range in case the displacement ductility around 3 and larger.