Abstract：Eight deep beams with lightweight aggregate concrete and two deep beams with normal weight concrete were tested under symmetrical concentrated load to investigate their shear behavior. The effect laws of web reinforcement ratio and beam depth on failure process and modes, load-deflection curve, characteristic load, diagonal crack propagation and strain in reinforcement were examined. The action mechanism of web reinforcement on the shear capacity and size effect of the deep beam was emphasized. To quantify the contribution of web reinforcement in the shear mechanism, a modified strut-and-tie model(STM)was established, in which the web reinforcements were considered as vertical ties. Moreover, based on evaluation and analysis on typical strut efficiency factor models, the accuracy of modified STM was verified. The test results indicate that all ten beams failed in the shear-compression mode, which was independent on size. The existence of web reinforcement can limit the spalling of concrete. The normalized diagonal cracking and ultimate shear load will increase with the web reinforcement ratio and a significant reduction in maximum diagonal cracking width can be observed. The web reinforcement can resist the internal tensile stress of the inclined section and form effective lateral restraint on the concrete strut, thus mitigating the effect of size effect. Compared with the original STM, the improved STM can reflect the contribution of vertical web reinforcement to the shear strength better. Generally, the predicted shear capacity by the improved STM with the ACI 318-19 strut efficiency factors is in good agreement with the experimental values.
吴涛 杨雪 刘喜 魏慧. 腹筋对轻骨料混凝土深受弯构件受剪性能及尺寸效应影响的试验研究[J]. 土木工程学报, 2022, 55(4): 1-11, 22.
Wu Tao Yang Xue Liu Xi Wei Hui. Experimental analysis on effect of web reinforcement on shear behavior and size effect of lightweight aggregate concrete deep beams. 土木工程学报, 2022, 55(4): 1-11, 22.
