Multi-ribs repair of thin steel plate shear walls damaged by earthquake: Comparison of orthogonal and oblique multi-ribs

• Two-stage tests study multi-ribs repair effectiveness on seismic-damaged steel walls. • FE model is established and multi-ribs repair simulated via birth-death element method. • Numerical simulation reveals repair stress mechanism and proposes multi-ribs improvement scheme. To study the repair methods of thin steel plate shear wall (SPSWs) after seismic damage, this paper conducts two-stage quasi-static tests on three SPSWs specimens with a scale ratio of 1/3, and compares and analyzes the hysteretic performance of unrepaired specimen, orthogonal multi-ribs repair specimen, and oblique multi-ribs repair specimen under the action of two earthquake. The results show that the orthogonal multi-ribs repair increases the bearing capacity of the seismic-damaged SPSWs by 11.46 %, the initial stiffness by 67.08 %, the energy dissipation capacity by 105.12 %, and the ductility by 11.14 %. The oblique multi-ribs repair increases the bearing capacity of the seismic-damaged SPSWs by 22.83 %, the initial stiffness by 88.01 %, the energy dissipation capacity by 126.26 %, but the ductility decreases by 3.34 %. Therefore, the oblique multi-ribs repair method is more effective in improving bearing capacity, stiffness and energy consumption. Orthogonal multi-ribs repair method can be adopted to improve ductility. In addition, multi-ribs repair can provide effective out-of-plane support for the wall plate and reduce the wall plate buckling deformation, among which the oblique multi-ribs repair method is more effective. The use of the birth and death element method in numerical simulation can effectively realize the repair process of multi-ribs. Compared with orthogonal multi-ribs, the stress development of oblique multi-ribs repair is more prominent, and the degree of participation is higher. Adding an orthogonal frame around the oblique multi-ribs can further improve the hysteretic performance of SPSWs and suppress the out-of-plane deformation of the wall plate.