配置竖向预应力筋混凝土箱梁抗剪性能试验

通过对2组配置竖向预应力筋的钢筋混凝土箱梁进行受剪试验,研究了竖向预应力筋张拉与不张拉,预应力孔道灌浆与不灌浆对混凝土箱梁抗剪性能的影响,对比分析了不同参数下试验梁的破坏形态、裂缝行为、荷载-挠度关系、开裂荷载、抗剪承载能力、腹板应变以及竖向预应力筋应变等的发展规律.结果表明:对于本文试验梁,竖向预应力可将开裂荷载提高16%,竖向预应力筋张拉端的抗剪承载力比不张拉端增加2.3%,不灌浆端的抗剪承载力比灌浆端减小9.3%.由此说明,适当地施加竖向预应力可以较好地提高腹板开裂荷载,并对抗剪承载力有积极贡献,但如果灌浆不饱满则会对抗剪承载力产生很大折减.

Experimental Study on the Shear Behavior of Reinforced Thin-wall Box Girders with Vertical Prestressed Tendon

This study investigated the shear behavior of two reinforced thin-wall box girders with vertical prestressed tendon. Whether the vertical tendons were prestressed or not and the ducts were grouted or not were comparatively studied. The experimental study addressed diagonal cracking behaviors, crack patterns and width, load-deflection relationship, the web strain and stirrup strain, as well as ultimate shear capacity. The test results have shown that, the cracking load of box girder with prestressing force is about 16% higher than those without, and the effect of prestressing force only increases by about 2.3% for ultimate shear capacity. Meanwhile, the shear resistance of girder without grouting is about 9.3% lower than those with ducts well grouted. Through the comparison of test girders, it has been found that the vertical prestressing force can improve the diagonal cracking load and shear capacity. The grouting quality for vertical prestressed ducts is of great importance to the shear behavior of the box girder.