An Innovative Shape Memory Alloy Damper for Torsionally Coupled Seismically Excited Structures

Superelastic shape memory alloy (SMA) is a potential candidate for use in structural damping devices due to its unique mechanical properties. A class of novel re-centring damping device (RDD) is presented. Being configurated simply, the device comprises two functional groups of SMA strands, such as the pre-tensioned strands and the un-pre-centering strands, resulting in a perfect energy dissipation compatible with the negligible residual displacement. Based on the Lagoudas constitutive model and the mechanical analyses, the theoretical model of RDD is established, and comparisons of experiments and simulations validate its effectivity. Time history and energy analyses of an asymmetric damped single-floor building under bi-directional earthquakes are performed. Results show that with the ratio of cross-sectional area of un-pre-tensioned strands to pre-tensioned strands being 1 or 2, the RDD can provide appropriate damping and stiffness to attain the reduction of the coupled lateral-torsional response for the asymmetric structure and the lower cost simultaneously.