2020 Volume 76 Issue 4 Pages 386-402
This paper proposes an evaluating equation to estimate capacities of beam action in shear resistance mechanisms of reinforced concrete (RC) beams for construction of simplified theoretical evaluating equations of the shear capacity. The fundamental equation was derived by the assumption that plane sections remain plane and by equilibrium conditions of the free body in the beam action which was separated by formulized inclined crack paths based on elastic solutions inside the vertical stress non-predominant region. The crack opening model, shear transfer model and tension softening model along the inclined crack paths were proposed based on direct shear experiments by using plain concrete specimens whose heights were 65 mm to 800 mm. The evaluating equation for capacities of beam action was constructed by applying these models based on the direct shear experiments. The static loading experiments and finite element (FE) analyses for RC beams whose shear span ratios were 1.0 to 3.0, and whose effective depths were 200 mm to 1600 mm were conducted to verify accuracies of the evaluating equations. As a result of the experiments and FE analyses, it was indicated that when the load carrying mechanism transition region was relativity small, the ratios of capacity of beam action for shear capacity were approximately same values independently of magnitude of its capacities, and that the ratios were governed by the shear span ratios. It was made clear that the evaluating equation could be evaluate for the ratios of estimated value for observed value with following accuracies: the averaged value was 1.0, the standard deviation was 0.10, and the coefficient of variation was 10.0 %.
