ACI 318-14 analyzes reinforced concrete corbel by shear friction (SF) and/or strut-and-tie modeling (STM). This work presents the results of experimental tests conducted on three reinforced concrete corbels that had a height of 390 mm and a width of 115 mm. The corbels had different shear span to effective depth ratios (a/d), which were 0.5, 1 and 1.5, respectively. Each test specimen was analyzed using both SF and STM to make a comparison between the experimental results. The cracking load, failure load, deflection, crack pattern, steel reinforcement strains, concrete surface average strains and locations of failure were recorded and discussed for the tested corbels. The findings revealed that, in the case of corbels with a/d = 0.5, the shear friction ultimate capacity ($P_{\mathit{SF}})$ and the STM ultimate capacity ($P_{\mathit{STM}})$ were less than the experimental failure load ($P_f)$ by about 15% and 22%, respectively. In addition, $P_{\mathit{SF}}\mathrm{a}\mathrm{n}\mathrm{d}{P}_{\mathit{STM}}$ were less than $P_{\mathit{f}}$ by about 18% and 27%, respectively, when a/d = 1. In contrast, in the case of a/d = 1.5, $P_{\mathit{SF}}\mathrm{a}\mathrm{n}\mathrm{d}{P}_{\mathit{STM}}$ were less than $P_f$ by about 32% and 37%, respectively. In conclusion, in the case of a/d < 1, both STM and SF can be used, although STM is more conservative due to its safety factors. In the case of a/d = 1–2, STM is more accurate than SF. However, if a/d exceeds 2, the corbel should be treated as a conventional cantilever beam.

ACI 318-14通过剪切摩擦力（SF）和/或支撑-拉杆模型（STM）分析钢筋混凝土牛腿。这项工作展示了对三个高度为390 mm，宽度为115 mm的钢筋混凝土牛腿进行的实验测试的结果。牛腿的剪切跨度与有效深度之比（a / d）不同，分别为0.5、1和1.5。使用SF和STM分析每个试样，以比较实验结果。记录并讨论了所测试的牛腿的开裂荷载，破坏荷载，挠度，裂缝模式，钢筋加固应变，混凝土表面平均应变和破坏位置。研究结果表明，对于a / d = 0.5的牛腿，其剪切摩擦极限容量（$P_{\mathit{SF}}）$ 和STM的极限容量（$P_{\mathit{STM}}）$ 小于实验失败负荷（$P_F）$分别减少约15％和22％。此外，$P_{\mathit{SF}}\mathrm{一种}\mathrm{ñ}\mathrm{d}{P}_{\mathit{STM}}$ 小于 $P_{\mathit{F}}$ 当a / d = 1时，分别降低约18％和27％。相反，在a / d = 1.5的情况下， $P_{\mathit{SF}}\mathrm{一种}\mathrm{ñ}\mathrm{d}{P}_{\mathit{STM}}$ 小于 $P_F$分别减少约32％和37％。总之，在a / d <1的情况下，尽管STM由于其安全性因素更为保守，但STM和SF均可使用。在a / d = 1-2的情况下，STM比SF更准确。但是，如果a / d超过2，则应将牛腿梁视为常规的悬臂梁。