Feasibility study of self-centring beam-to-column joints with posttensioned SMA strands

Abstract

The hysteretic behaviour of self-centring beam-to-column joints with posttensioned shaped memory alloy (SMA) strands under cyclic loading was studied in this paper. The material test of the dog bone-shaped SMA coupon was carried out and used to verify the applicability of the SMA constitutive in finite element (FE) models. The FE models of self-centring joints were established by ABAQUS, and the accuracy of the FE models was verified by the relevant test results available from the existing literature. With the verified FE modelling technique, the FE model of a novel self-centring joint was generated, and the numerical results were compared with the hysteretic performance of regular joints. Afterwards, the influences of the steel angle thickness, initial posttensioning force, vertical distance of two SMA strands on one side of the beam, and SMA strand number on the hysteretic performance of the novel joint were discussed in detail. The novel joint exhibited excellent seismic performance. The initial posttensioning force, numbers and vertical distance of SMA strands have significant effects on the stiffness, bearing capacity and self-centring performance of the proposed joints, but have little effects on the energy dissipation. The bearing capacity, stiffness, energy dissipation as well as the residual deformation of the proposed joints improve with increasing steel angle thickness.