Seismic Enhancement of Coupled Shear Walls Using Shape Memory Alloys

Abstract

This paper investigates the effectiveness of Shape Memory Alloys (SMAs) in enhancing the seismic behavior of coupled shear walls. First, SMA braces or strands are implemented in the shear wall openings for repairing and retrofitting purposes. A finite element program, SeismoStruct, is used to evaluate the seismic behavior of the controlled structure. For retrofitting purpose, a multi story concrete shear wall building with and without SMA elements is exposed to El-centro earthquake record for 15 seconds, followed with 25 seconds of damped free vibration. For repairing purpose, the structure in the first 40 seconds, is excited with El-centro earthquake and in the second stage, after adding the SMA braces, the same record is applied in second of 40 to simulate the aftershock. Results indicate that the proposed enhancement can successfully reduce the maximum displacements and permanent residual deflections of the existing shear wall structures. In the second part, as new designing technique, shear wall is reinforced with SMA reinforcement bars instead of conventional steel bars and/or with combination of SMA and steel reinforcement. ABAQUS finite element program is used to capture the seismic behavior of the concrete wall and the SMA material is implemented in the computer program by using FORTRAN as a subroutine material module. The structure is evaluated through nonlinear static as well as dynamic time history analyses. The results show that SMA reinforcement can significantly restore the residual displacement in the shear wall.