Experimental investigation of self-centering steel reinforced concrete coupled wall panels with replaceable energy dissipaters

Highlights

• A novel self-centering steel reinforced concrete coupled wall panels with replaceable energy dissipaters was put forward.

• Subassembly tests of the coupled walls with frame beams were conducted.

• Failure of the tested subassembly is mainly concentrated on energy dissipaters.

• The wall panels show a dual capacity of resiliency and energy dissipation.

Abstract

Resilience of structures is already the new issue and challenge in the field of earthquake engineering. In order to enhance the restorability of concrete wall panels and further use them in steel moment frames, a novel self-centering steel reinforced concrete coupled wall panels with replaceable energy dissipaters is presented in this paper. For this purpose, subassembly tests of the coupled walls with frame beams as boundary were carried out. Four full-scale specimens were tested under cyclic lateral loads. The initial prestress of post-tensioned (PT) steel bars and configuration of energy dissipaters were varied to investigate their impacts on lateral responses of the walls. The failure process, load-displacement relation, energy absorption capacity, residual deformation and force of PT steel bars were also investigated. Test results show that the three-stage nonlinear response is characterized by the sequential failure process of wall rocking, yielding of energy dissipater and yielding of PT steel bars. The initial prestress of PT steel bars greatly affects the initial stiffness, rocking load and residual deformation of the walls. Failure of the walls is mainly concentrated on the energy dissipaters. With the increase of energy dissipaters in quantitative terms or in type terms, the capacity of energy absorption is accordingly improved, but self-centering capacity is accordingly weakened.

Introduction

In past decades, the researches on seismic engineering were mainly focused on earthquake resistance, seismic isolation and energy dissipation. Nowadays, the earthquake resilience has gained popularity due to its capacity of quick restoration. In the field of structural engineering, the earthquake resilient structures are required to have a small residual deformation and concentrated damage. In this way, the loss of life and property under relentless earthquakes can be minimized. Self-centering structures are typical resilient structures. Generally, the utilization of post-tensioned technology or SMA (shape memory alloy) material can provide the restoring force for structures. The setting of replaceable energy elements can concentrate the damage and then protect the primary structures from severe failure. Owing to the advantages of self-centering structures, many research programs have been carried out, such as self-centering beam-to-column connections and/or moment frames [1], self-centering bracing members and/or braced frames [2], [3], self-centering dampers [4], self-centering steel columns [5], [6] or bridge piers [7], [8] and self-centering shear walls.

In the field of researches on the self-centering shear walls, prior researchers [9], [10] put forward the concept of a self-centering shear wall by using unbonded post-tensioned (PT) tendons with or without viscous damping. Then Perez [11] introduced a design-oriented analytical model to estimate the nonlinear lateral behavior of the post-tensioned precast concrete walls, which were previously tested by Kurama [9]. Restrepo [12] also tested three half-scale precast concrete jointed walls in a quasi-static manner. The walls can maintain their self-centering ability at the 3% drift level. Erkmen [13] investigated the self-centering behavior of post-tensioned precast concrete shear walls, and the configuration of end-anchorages for PT tendons was proved to be effective for self-centering capacity. By using the O-connectors as energy dissipaters, Henry [14] and Twigden [15] proposed an innovative precast wall system with end columns. Lu [16] carried out an experimental study of self-centering shear walls with horizontal bottom slits. The experimental results indicated that the proposed self-centering walls showed excellent self-centering capacity. Xu [17] developed the self-centering RC walls with disc spring devices at wall toes, the deformation ability and self-centering capacity of them were obviously better compared with conventional RC walls. In order to improve the energy dissipation ability, a self-centering hybrid shear wall with partially unbonded mild steel was suggested by Gu [18], and then the parameter analysis was performed by the multi-truss element model in OpenSEES.

For the coupled shear walls with self-centering function, a hybrid coupled wall system with RC wall limbs and posttensioning steel beams was put forward by Shen [19] and Kurama [20], and the related design procedures for estimating nonlinear lateral behavior were then developed. Guo [21] proposed and tested a jointed self-centering coupled wall system, the distributed friction devices were assembled between the precast concrete wall panels. Furthermore, Guo [22] upgraded the concrete frame buildings by using aforesaid self-centering concrete walls. Besides, in the category of timber structures, the self-centering coupled shear walls were also developed by some researchers. The hybrid self-centering steel-timber rocking walls were proposed by Hashemi [23], the slip friction connections were used between the rocking timber walls and the gravity steel columns. Ganey [24] conducted an experimental program of self-centering cross-laminated timber (CLT) walls. The capability of both self-restoration and energy dissipation for the walls was supported by the application of posttensioning steel bars together with mild steel U-shaped flexural plates. Additionally, seismic performance assessment for post-tensioned CLT shear walls was performed by Sun [25]. Hashemi [26] analyzed the seismic behavior of rocking CLT coupled walls with the innovative resilient slip friction joints.

In addition, the structures of self-centering moment frames with steel plate shear walls were widely studied. For these structures, it is clear that the self-centering beam-column connections provide the re-centering function and the steel plate shear walls are used to dissipate energy. Clayton [27], [28] conducted the experimental and numerical studies on the subassembly of self-centering steel plate shear walls. Sreekumar [29] performed the FEM analysis of self-centering moment resistant frames with or without steel plate shear walls. Xu [30], [31] applied both the self-centering energy dissipation braces and the steel plate shear walls to frame structures, the related cyclic tests and design considerations were then conducted. Jalali [32] carried out the nonlinear dynamic analysis and seismic assessment of self-centering steel plate shear wall structures. Besides, Liu [33] proposed an innovative resilient rocking column with replaceable steel slit dampers, then the column tests were carried out. Jiang [34], [35] put forward the earthquake-resilient prefabricated beam-column joints with replaceable dampers, and the related tests for cross-joints and T-joints were performed in succession.

In previous studies, a novel steel frame structure (SF) with self-centering steel reinforced concrete wall panel (SCW) has been put forward by Chao and Wu [36], as shown in Fig. 1. The precast wall panels are assembled between the adjacent floor beams through the post-tensioned (PT) steel bars, and the energy dissipaters at wall toes provide the energy-dissipating capacity. The wall toes are also protected by the rubber mats from crushing when the walls rock. In the paper, the coupled wall panels are considered in SF-SCW systems. Identically, the wall panels are connected to frame beams by PT steel bars. However, the replaceable energy dissipaters are assembled between the two wall panels, as illustrated in Fig. 2.

In this paper, attention is focused on cyclic behavior of the coupled wall panels in SF-SCW systems. Subassembly tests of the coupled walls with frame beams as boundary were carried out. The failure modes, load–displacement responses, self-centering ability and energy dissipation capacity of the walls were then checked by full-scale tests. The results allowed the impact of PT steel bars and energy dissipaters on wall responses to be assessed.