Retrofit of deep concrete coupling beams by a laterally restrained side plate

Abstract

The existing designs for deep reinforced-concrete (RC) coupling beams with low shear-span ratios and conventionally reinforced shear stirrups tend to fail in a brittle way with limited ductility and deformability under reversed cyclic loading. This paper aims to develop a new retrofitting method for existing deep RC coupling beams that can enhance the deformability and energy dissipation while maintaining flexural stiffness, improving the beams' performance during an earthquake. Experiments were conducted to test four half-scale deep RC coupling beams with the same geometry and reinforcement layout but with different retrofitting schemes. One beam was tested without retrofitting to act as a control, whereas the others were retrofitted by a bolted steel plate with or without adding a buckling restraining device. This study reveals that the deformation and energy dissipation of the deep RC coupling beams retrofitted with restrained steel plates improved while the flexural stiffness did not increase. Moreover, by using laterally restrained steel plates, the specimens had better postpeak behavior, a more ductile failure mode, and better rotation deformability. © 2011 American Society of Civil Engineers.