Online Model Updating for Advanced Hybrid Simulations

Online Model Updating for Advanced Hybrid Simulations

Hybrid simulations allow for the integration of numerical and physical substructures, such that the interactions between them can be considered in a seismic performance assessment. As a result, hybrid simulations can provide a cost-effective alternative to the shaking table test. However, conventional hybrid simulations are often restricted by the limited number of available facilities and specimens. Some structural elements that are similar to or the same as the physical substructures (PS) to be examined must be modeled in hybrid simulations. Therefore, the advantages and applicability of hybrid simulations diminish as a result of inaccurate modeling of the numerical substructures (NSs). To address the aforementioned issue, the researchers at Taiwan’s National Center for Research on Earthquake Engineering (NCREE) have developed the techniques of online model updating (OMU) to overcome such issues in hybrid simulations. The NCREE researchers proposed the gradient-based parameter identification (PI) method for OMU. The novelty of the proposed gradient-based PI method is to identify certain components of parameters during the 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 of the system. In this study, the proposed PI method is applied to the OMU schemes of the hybrid simulations of a steel panel damper (SPD) substructure conducted using a multi-axial testing system at the NCREE in 2017. In the hybrid simulations, the structure under investigation is a three-dimensional, sixstory moment-resisting frame (MRF) with four SPDs installed on each story. In these advanced hybrid simulations with OMU, only one SPD is represented as the PS, namely the SPD specimen. The remainder of the SPDs and MRF are represented as the NS. It was found that through the proposed PI method for OMU, the proper parameter values of the constitutive model representing the experimentally measured force versus the deformation relationships of the PS can be identified effectively. Using the identified parameter values, the constitutive 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 OMU technologies noted above have been upgraded and utilized in the recent hybrid simulations of an SPD substructure. These tests were successfully conducted using actuators mounted on a reaction wall and strong floor at the NCREE in 2019. The hybrid simulations of the SPD substructures demonstrate the effectiveness and benefits of OMU for advancing hybrid simulations and empowering testing facilities.