Experimental study on mechanical performance of FRP-steel laminate shear wall

In order to further improve the mechanical properties of steel plate shear wall, fiber reinforced polymer (FRP) is used in the steel plate shear wall structure system to construct an FRP⁃steel laminate shear wall (FSLSW). Improved tension field of FRP⁃steel laminate increases the design difficulty of connection between wallboard and joint frame, and the wallboard under the shear is prone to local failure at the connection. To resolve this problem, reasonable design method for bolted connection of strengthened FRP⁃steel laminates is proposed. 9 FRP⁃steel laminates with different ply angles and stacking sequences were tested in the bolted connections to study the shear resistance and failure mode, so the effectiveness of design method was verified. To evaluate the seismic behavior of FSLSW with strengthened bolted connections, two 1 / 3⁃scaled single⁃storey single⁃span shear wall specimens were tested under quasi⁃static loading. In the shear wall specimens, FRP⁃steel laminate and pure steel plate were chosen as the infill panels. To fully exploit tensile capacity of FRP, single⁃layer unidirectional CFRP sheeting was pasted on both sides of the steel plate and arranged in the opposite diagonal directions. Infill panel in FSLSW used additional fiber layers to reinforce the joint area. Seismic performance index, failure sequence, failure mode of FSLSW were evaluated. The results show that strengthening FRP⁃ steel laminate at the joint region can increase the shear bearing capacity of the joint, and adding CFRP 90° plies can compensate to some extent the sudden drop of bearing capacity observed from the specimen with only 45° plies, improving ductility of the joint. Behavior of FSLSW exhibits significant three⁃stage characteristics. In the elastic phase with the threshold drift of 0. 4%, the early bearing capacity is determined by the elastic modulus, and then the bearing capacity is gradually controlled by the buckling strength, causing the degradation of the improving effect from FRP; In the plastic phase with the threshold drift of 1. 5%, FRP leads to significant increase in bearing capacity and stiffness of steel plate, results in the increase of energy consumption, and imposes great restraint on the out⁃of⁃plane displacement of the wallboard. The maximum improving ratios of bearing capacity and stiffness are 30% and 31%, respectively. In the damage phase with the threshold drift of 3%, the contributions of FRP to the bearing capacity and stiffness of steel plate decrease gradually, and due to the fracture of FRP, the FSLSW degenerates to a pure steel plate shear wall. © 2023 Editorial Office of China Civil Engineering Journal. All rights reserved.