Rate‐of‐Loading Effects on Pseudodynamic Tests

A quasi‐static loading procedure is utilized in the pseudodynamic test method to simulate the seismic response of a structure. Hence, a major concern with the results of such tests is the rate‐of‐loading effects. This problem is addressed in the paper by studying the response of an elastic/viscoplastic system that has the rate‐dependent characteristics of a steel structure and is calibrated with the dynamic yield strength of mild steel obtained from prior experimental studies. While a wide scatter of experimental data can be observed, results of this study indicate that the dynamic yield strength of mild steel attained in the seismic response of a structure can be 30% higher than that developed in a pseudodynamic test, depending on the plastic strain rate induced. As a result, the inelastic response developed in a pseudodynamic test tends to be higher than that induced by an actual earthquake excitation. Nevertheless, the discrepancies are small for structures that have relatively low fundamental frequencies, provided the inelastic deformation is within a reasonable limit.