Self-centering eccentrically braced frames using shape memory alloy bolts and post-tensioned tendons

Abstract

Conventional eccentrically braced frames dissipate seismic energy through plastic deformation of link beams. However, large residual deformation after strong earthquakes often makes the damaged structure necessary for costly repair. This paper proposes a self-centering eccentrically braced frame system which incorporates shape memory alloy bolts and post-tensioned high strength steel tendons to provide a self-centering response behavior with moderate energy dissipation. An analytical model which has taken into account the super-elastic constitutive of shape memory alloys and the changing contact condition at the link-beam interface is formulated to predict the cyclic load behavior of the system. The feasibility of the proposed concept is demonstrated by cyclic load analysis of a prototype self-centering eccentrically braced frame. Finite element simulations are carried out to verify the analytical model and to further investigate the effects of the configuration details of the link-to-beam connection to the cyclic performance of the self-centering EBF system.