System identification of a bridge with lead–rubber bearings

This study develops an identification algorithm to investigate the dynamic properties of a base-isolated highway bridge equipped with lead–rubber bearings. A linear model is used for the substructure while a bilinear hysteretic model is chosen for the bearing system. The nonlinear hysteresis in the latter is characterized through a backbone curve. Application of Masing criterion enables the multivalue restoring force to be transformed into a single-value function. Consequently, the identification scheme which is effective for a linear system can be applied. A numerical example illustrates the proposed identification procedure and its applicability.