An Experimental Study on the Stirrup Effectiveness in Reinforced Concrete Beams

철근콘크리트보의 스터럽 효과에 관한 실험적 연구

The main objective of this study is to investigate the behavior of NSC and HSC beams with stirrups. Main variables were the concrete compressive strength and amount of vertical stirrups. A total of 24 beams was tested; 4 beams without web reinforcement and 20 beams with web reinforcement in the form of vertical stirrups. Main variables were 2 different compressive strengths of concrete of 26.9MPa and 63.5MPa, 5 different spacing of stirrups of 200, 150, 120, 100 and 90mm. Therefore, the results were compared with the strengths predicted by the equations of ACI code 318-99 and other researchers. The shear reinforcement ratio, where the test beams were failed simultaneously under flexure and shear, were $0.63{\rho}_{vmax}$ for NSC beams and $0.53{\rho}_{vmax}$ for HSC beams, respectively. The ACI code equation was found to be very conservative for shear design.

본 연구에서는 콘크리트 보의 전단거동에서 콘크리트 압축강도가 스터럽 유효성에 미치는 영향을 실험적으로 연구하였다. 전단파괴와 휨파괴가 동시에 일어나는 경계점은 대략 S=150mm부근으로 예상되며, 이때 전단철근비는 보통강도 콘크리트보에서는 $0.63{\rho}_{vmax}$ 이고, 고강도 콘크리트보에서는 $0.53{\rho}_{vmax}$로서 ACI 전단설계 산정식은 매우 안전측이라고 판단된다.