Utilizing realistic loading histories for the calibration of nonlinear components in seismic analysis

Abstract

Hysteretic models that simulate the hysteretic response of key structural components are generally employed in the nonlinear seismic analysis of structures. The calibration of hysteretic model parameters is crucial for achieving accurate analysis results in structural seismic assessment. The calibration process is commonly conducted by tuning hysteretic model parameters to align with the experimental results of a single component tested under standardized reverse-cyclic loading protocols. The underlying assumption of such a calibration method is that a structural model at the system level, using a well-tuned hysteretic model capable of accurately replicating the test results of a single component under a standardized incremental cyclic loading protocol, can predict the dynamic response of the structural system subjected to ground motion excitations with an acceptable level of accuracy. However, due to the simplified and often unrealistic loading protocols used for model calibrations, this assumption has been challenged recently by both numerical and experimental studies. In this paper, calibration methods utilizing more realistic loading histories are evaluated and compared to more conventional incremental cyclic loading-based protocols. The evaluation of calibration methods is carried out by quantifying the calibration relevance, utilizing a framework of virtual experiments that incorporates uncertainties in hysteretic model parameters. Analyses are conducted based on a case study of BRB components and BRBFs. Additionally, four calibration error quantification methods, considering characteristics in the transitional and plastic ranges of hysteresis curves of BRB, are proposed and compared. The results demonstrate that it is in fact advantageous to use realistic loading histories in component calibration of BRBs. An improved formulation of the calibration error is also proposed for the optimization of hysteretic parameters.