预应力张拉对箱梁底板混凝土的剥离效应研究

A Study on Surface Stripping Effect of Concrete Box Girder Floor Plate Due to Prestressed Tension

针对目前预应力混凝土箱梁设计和施工中的底板混凝土崩裂现象,考虑预应力孔道的应力集中和孔道对底板截面削弱的影响,采用空间有限元程序,研究了空间混凝土结构的计算理论和空间预应力的施加方法,分析了预应力张拉对箱梁底板混凝土的剥离效应。分析结果表明,预应力管道的曲线变化形式对径向力的影响较大;曲线突变处径向力和主拉应力大;长束的径向效应大于其余短束;腹板与底板交合部位的管道应力值大于其余管道周围的应力;靠近截面中心的管道变形大于腹板附近的管道变形。

During the course of construction and design,concrete located in floor plates sometimes occurs the phenomenon of surface stripping,the influence for stress concentration of prestressed pipe and section weakening is considered,the space finite element procedure is applied to study the calculation theory of space concrete structure and enforcement methods of spatial prestressed force,and to analyze the surface stripping effect of concrete located in floor plates due to prestressed tension.The results indicate;the curve variation form of prestressed pipe has effect on radial stress;the radial stress of the accident location for prestressed pipe is large,the radial effect of long wires is larger than it of short wires ; stress around pipe in intercourse part of web plate and floor plate is bigger than it of other parts ; deformation of pipe near side of section center is bigger than it of other parts.