Seismic design of three damage-resistant reinforced concrete shear walls detailed with self-centering reinforcement

Abstract

Recent studies have shown that the innovative shear walls detailed with a type of self-centering reinforcement and fiber reinforced concrete are effective in reducing the permanent displacement and concrete damage compared to conventional concrete (RC) shear walls. However, more investigation is required into the seismic design parameters, such as the inelastic rotational capacity and plastic hinge length of innovative shear walls. This paper investigates the response of three innovative walls cast with fiber-reinforced composites and reinforced with steel rebars and a type of self-centering reinforcement consisting of shape memory alloy (SMA) bars, glass fiber reinforced polymer (GFRP) bars, or high-strength steel strands. The response of each innovative wall is compared to that of a conventional RC shear wall called the control wall. Then, the inelastic rotational capacity, plastic hinge length, and self-centering of the innovative walls are discussed within the framework of the seismic design codes of North America.It is shown that innovative walls can undergo significant inelastic rotational deformations due to the use of ductile reinforcements in their boundary elements – SMA bars in the boundaries of steel-SMA reinforced wall and steel rebars in the steel-GFRP and the partially post-tensioned walls. The reinforcement with lower tensile strain capacities, such as PT strands and GFRP bars, were placed away from the boundaries of the steel-GFRP and the partially post-tensioned walls. It is also shown that the crack opening at the base of each innovative wall was greater in comparison to that of the control wall. This was due to the use of fiber-reinforced composites and self-centering reinforcements with low bonding stresses in the walls, which increased the rocking in the response of the innovative walls. It is shown that the plastic hinge in the steel-GFRP reinforced and post-tensioned walls was shorter than in the control wall since plastic strains were more concentration in steel rebars adjacent to the bases of the walls. In the steel-SMA reinforced wall, the plastic hinge length was longer than in the control wall due to the low bonding properties of the SMA bars compared to the control wall. The self-centering capacity of the innovative walls at different seismic performance levels is also discussed, and three improved self-centering objectives for the design of innovative walls are introduced.