预应力作用下箱梁桥的剪力滞效应研究

Shear Lag Effect Analysis of Box Girder Bridge Under Prestressing Effect

为了计算箱梁在预应力作用下的剪力滞效应,基于能量变分原理,结合预应力等效荷载法,建立了箱梁在直线、折线和曲线预应力布束方式下的剪力滞效应解析解。针对算例简支箱梁,研究了3种布束方式综合作用下箱梁的剪力滞效应,并和有限元板壳数值解进行了对比分析。以连续箱梁为例,研究了任意布束下梁体剪力滞效应的分布规律。结果表明:所提出的理论解析方法可以有效计算简支梁在预应力作用下的剪力滞效应;连续箱梁在预应力筋偏心锚固的梁端、折线布束的折角处和中支点等部位均会产生较大的剪力滞效应,由剪力滞效应产生的附加弯矩进一步增大了梁体的偏心距。

To calculate shear lag effect of box girders under prestressing effect, analytic method of shear lag effect with box girders under straight, harped and draped prestressing tendons was established based on energy variational principle and equivalent load method of prestressing. For an example of simple supported box girder, shear lag effects under three tendons were calculated and compared with numerical solution by shell finite element method. With continuous box girder as an example, the distribution of shear lag effects under arbitrary prestressing tendons was analyzed. The results show that the proposed analytic method can effectively calculate the shear lag effect of simply supported girders under prestressing effect. For continuous box girders, the larger shear lag effect presents in the regions of eccentric anchorage of prestressing tendon, angle of harped tendon and in-span supported point. The eccentric distance of girder is increased due to additional moment of shear lag effect.