Laterally restrained steel plate with stiffeners for seismic retrofitting of concrete coupling beams

Abstract

Existing deep reinforced concrete (RC) coupling beams with low shear span ratios and conventionally reinforced shear stirrups tend to fail in a brittle manner with limited ductility and deformability under reversed cyclic loading. Previous studies have developed a new retrofitting method with an unstiffened laterally restrained steel plate (LRSP) for existing deep RC coupling beams. By utilizing the post-buckling loading capacity of steel plate, the deformability and energy dissipation of the retrofitted coupling beams were enhanced while maintaining flexural stiffness during an earthquake. However, the occurrence of early plate buckling usually results in reduced strength, stiffness and energy dissipation capacity accompanied by significant pinching. In this study, half-scale deep RC coupling beams rehabilitated by LRSP with stiffeners were tested. The results demonstrate that the type of bolt connection greatly influences the performance of retrofitted coupling beams. The additional stiffeners can prevent plate buckling and ensure that the steel plate has a wider yield area and hence higher energy dissipation.