Behaviour and modelling of hybrid SMA-steel reinforced concrete slender shear wall

Abstract

Superelastic Shape Memory Alloys (SMAs) possess unique mechanical characteristics that make them appealing as alternative reinforcement for seismic applications; specifically, the capacity to recover large strains upon unloading, levels that would result in permanent deformations in steel reinforcement. An experimental study was conducted to assess the performance of a ductile, hybrid SMA-deformed steel reinforced concrete shear wall. A companion wall with deformed steel reinforcement only was also investigated. The walls were subjected to reverse cyclic displacements to failure. The results of the experimental program demonstrate that the hybrid SMA wall was significantly more effective at restoring resulting in marginal residual displacements after being subjected to drifts exceeding 4%. The hybrid SMA wall experienced similar lateral strength and displacement capacities to the steel reinforced wall. The hybrid SMA wall provided substantial, albeit less, energy dissipation and lower stiffness at yielding; the influence of these performance parameters on seismic behaviour is noted in the paper. A hysteretic constitutive model based on a trilinear envelope response, and linear unloading and reloading rules provided satisfactory simulations of behaviour of the SMA wall. Discrepancies in response are attributed to bond modelling of the smooth SMA bars. Furthermore, finite element analysis is also used to illustrate the effect of axial load on the re-centering capacity of the shear walls.