Advanced Numerical Modeling of Fiber-Reinforced Elastomeric Isolators (FREIs)

Abstract

Fiber-reinforced elastomeric isolators (FREIs) are relatively new type of elastomeric bearing that utilize fiber-reinforced polymer (FRP) material for the reinforcing material. FREIs have lower weight and potentially easier manufacturing process compared with conventional seismic isolators. The viability of FREIs has been investigated through a number of experimental tests studies. However, numerical modeling of FREIs is required to better understand their vertical and lateral response characteristics, and to investigate the response of isolated structures using FREIs. In this research, 3D finite element analysis (FEA) is carried out to investigate the vertical response of FREIs with various numbers of elastomer layers and reinforcing materials. In addition, the lateral response of FREIs is studied using 3D FEA. Experimental test results from three previously tested isolators were used to evaluate FEA models and subsequently, a series of FEA were carried out to investigate the sensitivity of the lateral response of FREIs to the direction of loading. A new computational model is proposed to enhance the time history analysis of structures seismically isolated with FREIs. The proposed Pivot-Elastic model is capable of predicting the complex lateral response of FREIs. In order to evaluate the predictions of the proposed model, nonlinear time history analyses of a two-storey steel moment frame structure seismically isolated with FREIs were carried out, and the predicted response of the structure was compared against the results from a previous shake table study. The lateral response of rectangular FREIs, a shape suitable for shear wall structures is investigated through experimental testing and 3D FEA. A series of time history analyses, using ten earthquake ground motions are carried out on a two-storey reinforced concrete shear wall structure seismically isolated using rectangular shape FREIs. The efficiency of the isolation system composed of rectangular FREIs was evaluated by investigating the seismic response of the structure with and without the seismic isolation system.