Online Model Updating for Hybrid Simulations of a Steel Panel Damper Substructure

Online Model Updating for Hybrid Simulations of a Steel Panel Damper Substructure

Hybrid simulations allow for the integration of numerical and physical substructures, such that the interaction between them can be taken into account in a seismic performance assessment. As a result, hybrid simulation can offer a cost-effective alternative to the shaking table test. However, conventional hybrid simulations are always restricted by the limited number of facilities and specimens. Some or many structural elements that are similar to or the same as the physical substructures (PS), must be modeled in hybrid simulations. Thus, the advantages and applicability of hybrid simulations diminish as a result of inaccurate modeling of the numerical substructures (NS). To address this problem, the gradient-based parameter identification (PI) method for Online Model Updating (OMU) was proposed by the researchers of Taiwan's National Center for Research on Earthquake Engineering (NCREE). A novelty of the proposed PI method is to identify certain parts of parameters during identification stages for different stress states, leading to a reduction in the number of design variables to be determined. The time consumed in computing the gradients can be reduced accordingly to improve the identification efficiency. In this study, the proposed PI method is applied to OMU schemes for hybrid simulations of a steel panel damper (SPD) substructure conducted using a multi-axial testing system at the NCREE in 2017. The structure under investigation is a three-dimensional, six-story moment-resisting frame with four SPDs installed on each story. In the hybrid simulations, only one SPD is represented with the PS, and the rest of the structure is represented with the NS. Through OMU, the proper parameter values of the constitutive model that are utilized to represent the observed force vs. deformation relationships of the PS, namely the SPD specimen, can be identified effectively. With the identified parameter values, the material models of relevant SPD elements in the NS can be rectified online during the hybrid simulations. The accuracy of the hybrid simulations can be improved accordingly. The actual hybrid simulations of the SPD substructure demonstrate the effectiveness and benefits of OMU with the proposed PI method for advanced hybrid simulations.