Influence of Early-Arriving Pulse-Like Ground Motions on Ductility Demands of Single-Degree-of-Freedom Systems

Rupture directivity effects cause a large pulse to arrive at the beginning of the motion. However, not all early-arriving pulses are caused by the forward-directivity. The main focus of this study is on whether forward-directivity records affect structures in the same manner as other early-arriving pulses. An extensive parametric study investigating the inelastic response of degrading and non-degrading SDOF systems is conducted. Results show that in the short period region (T<0.7 sec), the non-directivity early-arriving pulse-like motions impose larger ductility demands. For intermediate period (0.7 < T < 3.5) systems, directivity motions induce larger displacement demands.