Cyclic Behavior of Short Reinforced Concrete Coupling Beams Confined by Steel Plates
H.-Y. Zeng, J. Gitomarsono, A. J. Kawatu, W.-T. Chan, S.-C. Chiu, and M.-Y. Cheng
Appears on pages(s):
confinement; coupling beam; deformation; strength
A new composite coupling beam having steel plates that provide active confining pressure of approximately 0.05Asafc′ on each side of the reinforced concrete (RC) beam with an orthogonal reinforcement layout is proposed in this research. A weak (unconfined) portion was intentionally left by cutting off the steel plates at 1 in. (25 mm) distance away from the beam ends to absorb the majority of the inelastic deformation. Three coupling beam specimens with ln/h of either 1.5 or 2.5 were tested under lateral displacement reversals to evaluate the cyclic behaviors of the proposed coupling beams. Test results indicated that the use of steel plate confinement significantly enhanced the strength and deformation capacity of RC coupling beam specimens with orthogonal reinforcement layouts. The peak strength of the proposed coupling beams, Vpeak, can be adequately estimated by VMn, the shear corresponding to the development of the nominal flexural strength. The drift capacity of the proposed coupling beams exceeded 8.0%, which was 50% larger than that of specimens using diagonal reinforcement in compliance with ACI 318-19.