Keywords
Abstract
Composite shear walls are widely used to resist the lateral load in high rise-buildings nowadays; however, prior experimental tests have shown high damages and residual drifts at the plastic zone region. At present time, designing resilient buildings with low or no damage is one of main goal in performance-based seismic design of structures. In current research, a new design of an innovative low damage self-centering composite steel plate shear wall (SC-C-SPSW) equipped with unbonded posttension tendons (UPTs) is proposed to control the damage and the residual drift under seismic loading. To this end, five specimens including two composite steel plate shear walls (C-SPSW) and three SC-C-SPSWs were tested under gravity and reverse cyclic loading. The SC-C-SPSWs were detached using a pair of steel plates placed symmetrically under the wall boundary elements in order to form the bottom gaps with the foundation. The gap length, steel plate dimensions, and the initial prestressing on UPTs were considered as experimental parameters in this study. The construction details and the seismic performance including failure modes, damage progression, hysteretic response, and energy dissipation are presented in detail. The experimental results indicated that SC-C-SPSWs have excellent behavior in term of lateral strength and ductility and experienced low damage levels in comparison with C-SPSWs. The SC-C-SPSW walls experienced a large lateral displacement before initiation of the strength degradation, and the residual drifts were much smaller in comparison with C-SPSWs.
Introduction
Reinforced concrete shear walls are the most popular lateral load-resisting systems (LLRS) because they have a simple construction details and acceptable seismic behavior in squat and midrise buildings. However, RC-shear walls have relatively limited deformability and displayed extreme damage and a significant residual drift, especially in high seismicity zones (Su and Wong 2007; Zhao and Astaneh-Asl 2004). Composite shear walls were innovated for resisting the lateral loads of high rise buildings and covering the shortcoming of RC shear walls.
Many types of composite shear wall were developed using steel profiles, steel braces, and steel plates (Hossain et al. 2016: Wang et al. 2019; Wu et al. 2016). Many studies have been carried out to investigate the seismic response of different types of composite shear walls using experimental and numerical methods. Composite shear walls with vertical steel-encased profiles were experimentally tested by Dan et al. (2011a, b) and Liao et al. (2012) . It was concluded that the ductility and the flexural capacity of the wall were improved and the stiffness deterioration was much less in comparison with RC shear walls.
Composite plate shear wall-concrete encased (C-PSW/CE) prescribed in AISC 341-16 (AISC 2016) is a novel type of composite shear wall that consists of a steel plate with a reinforced concrete wall attached to one or two sides of the wall and steel or composite boundary elements. The experimental tests conducted by Zhao and Astaneh-Asl (2004) showed that the steel plate can effectively improve the seismic response and the concrete can protect the embedded steel plate from early bulking and corrosion.
Also, composite steel plate shear wall (C-SPSW), which consists of steel plate welded to steel chords and encased in the RC shear wall, was investigated by Wang et al. (2018) . It was pointed out that the steel plate can effectively carry the shear deformations, while the steel cords increase the flexural strength and wall ductility. A double-skin composite shear wall consists of two skins of faceplates with an infill of concrete connected together using shear stud connectors and tie rode anchors (Hossain and Wright 2004). Double-skin steel plate shear walls have many advantages in terms of strength, ductility, constructability, and seismic performance (Epackachi et al. 2015b; Qin et al. 2017; Rassouli et al. 2016). However, they suffer from early buckling of steel faceplates and the erosion of steel plates (Wang et al. 2018).
Compared with RC shear walls, composite shear walls have high efficiency in term of shear capacity, most likely larger shear stiffness, smaller thickness, high ductility and energy dissipation, and simple construction details. However, experimental observations indicated that by increasing the lateral drift, the composite shear walls experienced high damage and large residual displacement. In recent years, low-damage or damage-avoidance designs under earthquake loads have been raised to improve seismic performance of structures in terms of financial, functionality and resilience. To this end, resilient rocking or hybrid systems have been introduced to improve the seismic performance.
Reference & DOI
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