轨道交通连续刚构桥双薄壁墩受力优化方法分析

Optimization Analysis of Double Thin-wall Pier in Railway Continuous Rigid Frame Bridge

由于连续刚构桥双薄壁墩外侧墩柱处于较为不利的受力状态,为了研究该部位的受力优化方法,以某轨道交通50 m+74 m+50 m连续刚构桥为研究对象,建立三维梁单元有限元模型,分析了该桥双薄壁墩的受力特性。从对主梁和桥墩受力状态影响的角度,分别介绍体系转换前后在中跨合拢段施加顶力和在边跨合拢段施加压重两种方法对改善连续刚构桥双薄壁墩受力状况的作用。与施加顶力相比,施加压重对墩身轴力的改善效率更高,但是在改善轴压效果近似相同的前提下,该方法对改善墩身弯矩和剪力的效果要小于施加顶力。施加顶力和边跨压重均会对主梁内力产生不容忽视的影响。

The double thin-wall pier of a continuous rigid frame bridge is always under unfavorable stress condition. To study its optimization design method, a 3-D beam element FEA model was established for a railway continuous rigid frame bridge. Mechanical behaviors of the double thin-wall were analyzed. Two methods were introduced ： （ 1 ） imposing jacking pressure before mid span closing, and （2） applying saddle weight before side span closing. Main conclusions drawn include： The imposing saddle weight method is more efficient on improving the axial force of the pier compared with jacking pressure ; The jacking force and saddle weight imposing methods both produce small influences on the girder internal force.