Seismic damage assessment method for reinforced concrete frame structures through nonlinear model updating using an optimization strategy

This study aims to propose a seismic damage assessment method for reinforced concrete (RC) structures using a nonlinear model updating technique for the RC frame. The nonlinear hysteretic behavior of structural members in the RC frame under seismic loads is simulated using a modified Ibarra-Krawinkler (MIK) model in the proposed nonlinear model updating technique. The main parameters in the MIK model are set as decision variables in the model updating process and determined using an optimization technique. A displacement response to earthquakes is set as the objective function. In the formulation, constraint functions considering the physical rationality of the rotation angle in the MIK model that simulates the nonlinear behavior of a local structural member and the consistency of the natural period between the model and target structure are presented. The updated model is used in the seismic damage assessment of RC structures through hinge propagation and is applied to the two-dimensional (2D) and three-dimensional (3D) RC frame structures. The structure’s optimal nonlinear model is examined via model updating, while the applicability of the proposed method is verified by investigating the seismic response and damage detection performance of the model. The adequacy and validity of the two constraint functions set in the formation are also examined.