Online explicit model updating of nonlinear viscous dampers for real time hybrid simulation

Real-time hybrid simulation (RTHS) is a testing method by which a structural system is divided into analytical and experimental substructures. This paper proposes a methodology to conduct RTHS for structures that use passive nonlinear viscous dampers (NLVDs), some of which are physically tested in the experimental substructure and others that are in the analytical substructure via online model updating (OMU). The proposed methodology uses the response of a physically modelled NLVD to improve the response prediction of the numerically modelled NLVDs. An explicit solution of the constitutive relations of the Nonlinear Maxwell Model (NLMM) is proposed to perform a non-iterative real-time state determination of a damper modelled using the NLMM. The model updating is performed using the Unscented Kalman Filter (UKF). RTHS of a two-story reinforced concrete structure subjected to strong earthquake ground motions (including both near-field and far-field recorded earthquake records) are performed to validate the model updating procedure.