The loss of vertical prestress on webs of a concrete box girder bridge causes web cracking. The vertical prestress loss is related to the construction technology, machinery tools, control precision and other factors. Through the calculation and analysis of five items of prestress loss, the contribution value of each item to the vertical prestress loss of the webs was discussed. The influence mechanism of vertical prestress loss on each part of the box girder was studied by numerical analysis using the finite element model. The results are as follows: ① The most significant effect of vertical prestress loss is the loss of anchor deformation and reinforcement shrinkage, while the vertical prestress loss caused by the friction between prestressed tendons and pipes, elastic compression of concrete, reinforcement relaxation, shrinkage and creep of concrete is small;②In the vertical box girder with equal section, the smaller the beam height, the greater the effect of vertical prestress loss on the web stress; In the box girder with variable section, the effect of vertical prestress loss on the cantilever end web is greater than that on the cantilever root. ③ The emphasis of vertical prestressing control is to optimize tensioning anchorage machinery tools and improve the construction technology.
关键词
桥梁腹板/竖向预应力/混凝土裂缝/预应力损失
Key words
bridge webs/vertical prestress/concrete cracks/prestress loss
维普
万方数据