大跨径梁桥墩顶块空间应力数值分析及优化设计

Numerical analysis and optimal design for block on pier top of long span beam bridge

为了优化大跨径连续梁桥和连续刚构桥墩顶块的分析方法,对墩顶块几何尺寸的确定方法、预应力的模拟方法、荷载的施加方法、边界条件的选取进行了分析,并且通过参数分析提出了有效的解决方法。在此基础上,提出了考虑普通钢筋配筋率影响的允许应力增大系数法,明确了墩顶块三维有限元计算结果的判断方法;提出了墩顶块倒角优化设计方法和一种新型的墩顶块形式。研究结果表明:墩顶块顶板、底板和腹板应力增大系数参考值为1.05,横隔板为1.10,倒角为1.55;只要墩顶块有限元模型尺寸足够大,加载方式对墩顶块关心位置计算结果的影响可以忽略;对连续梁墩顶块而言,倾斜隔板墩顶块各部分应力峰值较竖直隔板墩顶块有了很大的改善。

In order to optimize the analyzing method of block on the pier top of long span continuous beam bridge and continuous rigid frame bridge,the analysis method for size of geometric model,pre-stressing simulation method,loading method,boundary conditions simulation were presented.On the basis of numerical results,the effective practical analysis methods of block on pier top were obtained.Allowable stress intensification factor considering the effect of ratio of ordinary steel area to concrete was presented to further clarify the calculation results.Chamfering optimization design methods and a new form of block on pier top were proposed.The results show that：for the pier top block,the reference value of magnification factor of roof,floor and web stress is 1.05 and diaphragm is 1.10,chamfer is 1.55;as long as the finite element model of the pier top block size is large enough,the impact of calculation on the pier top block under different loading positions can be ignored;for continuous beam of the pier top block,the peak stresses of proposed bulkhead pier tilted top block of the partition part are greatly improved than the ones of vertical pier top block.11 tabs,4 figs,9 refs.