竖向预应力筋对连续刚构桥受力影响分析

竖向预应力筋在连续刚构桥中主要起控制腹板主拉应力的作用,根据现行规范分析了不同长度竖向预应力筋的损失比例,提出了减小竖向预应力损失的几种措施;针对目前设计中采用的滞后张拉竖向预应力筋的方法,开展了3种滞后张拉竖向预应力筋方式对连续刚构桥受力的影响分析,在此基础上提出了竖向预应力合理张拉时间的建议;建立了箱梁腹板的细部有限元模型,详细地分析了腹板在单根竖向预应力筋作用下的应力分布情况和腹板上缘出现拉应力的原因,据此提出避免上缘拉应力出现的构造措施。

Mechanic Analysis on Vertical Prestressing Bar to Continuous Rigid Framed Bridge

Vertical prestressing bars play a great role in controlling the principal tensile stress of webs.According to existing norms,the ratio of the vertical prestress loss to different length of the vertical prestressing bars is analyzed.In view of the current design of the delay tensioning vertical prestressing bar,the impacts to the continuous rigid-framed bridge by each of the three different delay tensioning methods is analysed,and the reasonable prestressing time is given based on the analysis.The reasons for the webs in a single vertical prestressing bars under the stress distribution and on the edges of web tensile stress are analyzed in detail,by establishing the detailed FEM simulation model of webs,and then the advice how to avoid stress on the edge of tectonic is given.