Experimental Testing and Reliability Analysis of Repaired SMA and Steel Reinforced Shear Walls

Title: Experimental Testing and Reliability Analysis of Repaired SMA and Steel Reinforced Shear Walls
Authors: Zaidi, Mohammed
Date: 2016
Abstract: Superelastic Shape Memory Alloys (SMAs) are being explored as alternative reinforcing materials to traditional deformed steel reinforcement for seismic applications. The main advantage is the ability of the SMA to recover large nonlinear strains, which promotes the self-centering phenomenon. The primary objective of this research is to present the performance, before and after repair, of slender reinforced concrete shear walls, one reinforced internally with SMAs in the boundary zones within the plastic hinge region and other control wall reinforced with conventional steel only. The repair procedure included removal of damaged concrete within the plastic hinge region, replacing fractured and buckled reinforcement, followed by shortening of the SMA reinforcement in the boundary zones of SMA wall. The removed concrete was replaced with self-consolidating concrete, while the concrete above the plastic hinge region remained intact. The SMA reinforced concrete shear wall (before and after repair) exhibited stable hysteretic response with significant strength, and displacement and energy dissipation capacities. In addition, the walls exhibited pinching in the hysteretic response as a result of minimizing the residual displacements due to the restoring capacity of the SMA reinforcement. The results demonstrate that SMA reinforced components are self-centering, permitting repairing of damaged areas. Furthermore, the SMA reinforcement is re-usable given its capacity to reset to its original state. The length of the SMA bars in the original and repaired wall, in addition to the presence of starter bars in the original wall, were significant factors in the location of failure of the walls. The conventional steel wall prior to repair was unstable due to large residual displacements experienced during the original test. After repair the wall exhibited ratcheting in hysteretic response but with significant strength. The conventional wall, before and after repair, dissipated more energy than the SMA wall. This was the result of the wider hysteretic loops with reduced punching, but at the cost of large residual displacements. The starter bars in the conventional wall before repair controlled the location of failure, while the presence of couplers in the plastic hinge region was the main factor in determining the failure location in the repaired conventional wall.
URL: http://hdl.handle.net/10393/35357
CollectionThèses, 2011 - // Theses, 2011 -