钢筋锈蚀对混凝土梁抗扭承载力的影响

Effects of steel corrosion on concrete beam torsional bearing capacity

为了研究钢筋锈蚀对纯扭构件承载力的影响,基于对12根模型梁的快速锈蚀,对不同锈蚀率的混凝土梁进行纯扭加载试验。构件初始裂缝大部分出现在1/3梁跨处附近,很少出现与初始斜裂缝相一致的极限主裂缝。锈蚀梁力位移曲线没有明显的屈服阶段,构件破坏呈脆性。梁的抗扭极限承载力随锈蚀率的升高而降低,在相同锈蚀率下箍筋锈蚀构件的承载力下降较多,延性降低趋势显著。研究表明,钢筋锈蚀削弱了构件开裂前的抗扭刚度,降低了钢筋自身的抗扭能力,导致混凝土梁的抗扭承载力下降。考虑了钢筋锈蚀的变角空间桁架法计算结果与试验结果符合较好。

In order to study effects of steel corrosion on the torsional bearing capacity of concrete beams, considered different corrosion rate ,pure torsional loading test were carried out for 12 fast-rust model beams. Most of the initial cracks appeared near the 1/3 beam- span in the component,but the limit main crack was rarely consistent with the inclined initial crack. There is no obvious yield stage in force-displacement curve of corroded beam, and the damage type is brittle failure. The beam torsional bearing capacity increases with the corrosion rate decreasing. In the same corrosion rate ,bearing capacity of the beams which stirrup corroded becomes much less, and the ductility tends to decrease significant. Considered the steel corrosion, the variable-angle spatial truss model has better precision in calculation. Studies show that the steel corrosion results in decreasing the torsional bearing capacity throug weakening torsional stiffness before cracking, and reducing the steel torsional capacity.