An elastoplastic damage model for energy dissipation devices

As some of the more effective passive dissipation devices, metallic plate dampers increase the capacity of a structure during a significant earthquake by absorbing seismic energy through the yielding of a steel plate. These devices are retrofitted to structures and are regarded as critical elements in seismic protective systems or passive energy dissipation systems. Thus, in order to understand the inelastic behavior of metallic dampers and design them at a reliable level, an elastoplastic two surface damage model is proposed. This damage model is formulated with a cumulative continuum damage concept and a thermodynamic approach based on an existing two surface model that was formulated using isotropic and kinematic hardening rules. The isotropic hardening rule produces the expansion of the outer surface, while the kinematic hardening rule stands for the translation of the inner surface. This damage model is then implemented through a user subroutine in a commercial finite element analysis code, and numerical results are compared with experimental data for the validation of the model. The model parameters for this analysis were established on the basis of a series of optimization processes. Finally, the proposed two surface damage model predicts the cyclic response very well and provides good agreement with experimental data. Thus, finite element results can be used to develop a better understanding of metallic plate dampers under cyclic loading.