预应力混凝土箱梁桥顶板上的开裂问题

介绍了我国几座预应力混凝土箱梁桥顶板开裂的情况,结合沙洋汉江公路大桥的加固工程,分析了箱梁顶板的横向内力。通过实桥计算,发现日照温差在箱梁顶板上产生较大的横向温度应力,在工程设计中忽略该项应力的计算是不合理的。对在车轮荷载作用下的箱粱顶板横向弯曲问题,应用高阶有限条法进行数值分析,并与平面框架法的计算值作了比较,其结果有出入。本文就上述问题对预应力混凝土箱梁顶板开裂的原因进行探讨,对今后设计,提出了几点建议。

The Problem of Cracking in the Top Slab in Prestressed Concrete Box Girder Bridges

The paper introduced the case of cracking in the top slab in some pre-stressed concrete box girder bridges in our country. Transverse internal forces on the deck of the box girder are analyzed according to the consolidated engineering of Shayang Hanjiang Bridge. Calculating the built-up bridges, we've found that transverse temperature stresses on the top slab caused by sunshine temperature difference are relatively great, they are not to be neglected in the designs. Besides, in analyzing the problems of transverse bending in decks of the box girder under vehicle loads, the numerical soiutions obtained by using high order finite strip method are compared to those obtained by using the plane frame method, the results are found to be not in good agreement. Therefore, the paper analyzes some causes of cracking in the top siab in prestressed concrete box girder and some important suggestions are proposed concerning the above problems.