This study proposes a theoretical evaluation equation for the capacities of beam action in reinforced concrete (RC) beams. The equation reflects the dowel action of the main reinforcements for the development of rational evaluation methods for the shear capacity. To verify its accuracy, a static loading experiment and finite element (FE) analyses were conducted for the beams with 2.1 to 9.4% of the main reinforcement ratio. The fundamental equation that reflects the dowel action of the main reinforcement was developed using the equilibrium condition of the free body in beam action. The decrease in crack width by the main reinforcement, which was required to calculate dowel force, was derived by the assumption of perfect bonding between concrete and rebars. The governing equations were formulated to derive the experimental values of the contributing forces of arch action and beam action in RC beams with cross sections of multilayered rebars. The calculated values indicated that changes in load-carrying mechanisms could be explained from the equation. The accuracies of the proposed equation and evaluation equations of shear strengths based on design codes were compared against the capacities of beam action based on the analytical results. As a result, for the values based on the proposed equation, the coefficient of variation was 7.7% and the highest accuracy was observed in all the cases examined. It was confirmed that the proposed equation accurately reflected the dowel action of the main reinforcements and guaranteed rationality owing to its theoretical background.

本研究提出了钢筋混凝土 (RC) 梁中梁作用能力的理论评估方程。该方程反映了主要钢筋的销钉作用，以制定合理的抗剪承载力评估方法。为了验证其准确性，对主配筋率为 2.1% 至 9.4% 的梁进行了静载试验和有限元 (FE) 分析。反映主钢筋销钉作用的基本方程是利用梁作用中自由体的平衡条件开发的。计算销钉力所需的主筋造成的裂缝宽度的减少是通过假设混凝土和钢筋之间完美结合而得出的。制定控制方程以推导出具有多层钢筋横截面的 RC 梁中拱作用和梁作用的贡献力的实验值。计算值表明承载机制的变化可以从方程解释。将基于设计规范的抗剪强度方程和评价方程的精度与基于分析结果的梁作用能力进行了比较。结果，对于基于建议方程的值，变异系数为 7.7%，并且在所有检查的情况下都观察到了最高的准确度。证实了所提出的方程由于其理论背景而准确反映了主筋的销钉作用并保证了合理性。