Self-centering modularized link beams with post-tensioned shape memory alloy rods

Abstract

Link beams in seismic resistant structures are usually designed to undergo severe plastic deformation to provide required ductility and energy dissipation on the occurrence of strong seismic events. The plastic deformation of link beams results in permanently deformed structures that are costly to repair after the earthquake. To reduce permanent deformation of link beams, a new concept of self-centering link beam using post-tensioned shape memory alloy rods to simultaneously provide re-centering force and energy dissipation capacity is proposed. It has two basic configurations and is modularized for the ease of fabrication and erection. An analytical model that is able to predict the cyclic loading behavior of the self-centering modularized link beam is presented. Based on the analytical model, parametric studies are carried out to investigate the effects of design parameters on the performance of the self-centering modularized link beam and also to show the performance range of the self-centering modularized link beams under given ranges of design parameter values. Typical examples are presented to demonstrate that the proposed self-centering link beam can be designed to exhibit performance comparable to that of conventional link beams in addition to re-centering capability.