U形预应力钢板箍加固T形截面钢筋混凝土梁受剪性能试验研究

为改进T形截面钢筋混凝土(RC)梁的受剪加固工艺，提出了一种采用U形预应力钢板箍对T形截面RC梁进行受剪加固的技术。采用简支梁跨中集中力加载的方法，完成了1个足尺未加固RC梁和5个足尺加固RC梁的单调静载试验，研究U形钢板箍间距和预应力水平对加固RC梁受剪性能的影响。通过试验得到了试件的损伤发展过程、破坏形态、荷载-变形曲线以及钢板箍、钢筋和混凝土的应变曲线。研究表明：采用U形预应力钢板箍可有效提高既有T形截面RC梁的斜截面受剪承载力，试件受剪承载力随钢板箍间距的减小而提高，最大提高幅度可达46.1%。当钢板箍间距小于400mm时，加密钢板箍对试件受剪承载力的提高作用逐渐减弱。钢板箍预应力水平在0.35以上时，进一步提高预应力水平对试件受剪承载力无明显影响。提出了U形预应力钢板箍加固T形截面RC梁受剪承载力的计算式，计算结果与试验结果吻合良好，可为既有T形截面RC梁的加固设计提供参考。

Experimental study on shear performance of T-shaped RC beams strengthened with U-shaped prestressed steel jackets

To improve the shear strengthening technology of existing T-shaped reinforced concrete (RC) beams, a retrofitting technique using U-shaped prestressed steel jackets(PSJ) to enhance the shear performance of T-shaped RC beams was proposed. One full scale RC beam and five full scale strengthened RC beams were tested using simply supported beam method under monolithic loading. The influences of spacing(sJ) and prestressing level(α) of PSJs on the shear performance of the T-shaped RC beams were studied. The damage development, failure modes, load versus deflection curves of the specimens and strain development curves of PSJ, reinforcement and concrete were obtained from the test. It is indicated that the shear strength of T-shaped RC beams can be effectively enhanced after retrofitting by U-shaped PSJs. The shear strength of specimens increases with the decrease of the PSJ spacing and the maximum increment of shear strength of specimens is 46.1%. But when the PSJ spacing is less than 400mm, the enhancing effect due to the use of PSJ on the shear strength of specimens decreases gradually. The stressing level of PSJs has no obvious effect on the shear strength of specimens when it’s higher than 0.35. The calculation method of the shear strength of retrofitting T-shaped RC beams was proposed. The test results of the shear strength of specimens agreed well with the calculation ones and therefore can be referenced for the retrofit design of existing T-shaped RC beams.