Title: Seismic Performance of Moderately Short Concrete Coupling Beams with Various Reinforcements
Author(s): Wan-Shin Park, Thomas H.-K. Kang, Sanghee Kim, and Hyun-Do Yun
Publication: Structural Journal
Appears on pages(s): 141-154
Keywords: coupling beam; ductility; energy dissipation; moderately short beam; steel fibers; structural performance
The purpose of this study is to investigate the effect of various reinforcement configurations on the seismic performance of diagonally reinforced coupling beams in part of coupled reinforced concrete wall systems. A total of four approximately half-scale concrete coupling beams were fabricated between concrete blocks and tested under cyclic shear distortions in a double curvature condition. All four specimens had the same clear span-depth ratio (ln/h) of 2 and the same reinforcement except for the transverse reinforcing details and presence of steel fibers. The control reinforced concrete (RC) coupling beam was designed with full section confinement according to the seismic provisions of the ACI 318-19 code, except for the steel volume, whereas the other specimens were provided with reduced transverse reinforcement and/or steel fibers for the purpose of improving the constructability. The top and bottom horizontal bars were sufficiently embedded into the wall as opposed to the ACI 318-19 recommendation. Test results indicate that the transverse reinforcement configuration and horizontal reinforcement embedment had a significant impact on the behavior both at the linear and nonlinear deformation ranges. For the coupling beams confined only by closed outer stirrups but without inner crossties, the addition of hooked steel fibers at a volume fraction of 0.75% provided similar structural performance compared with the RC coupling beam featuring full section confinement.