大跨度斜拉桥索梁锚固区三维有限元仿真分析

采用不同建模方法,对大跨度斜拉桥索梁锚固结构—钢锚箱进行三维非线性有限元仿真分析,并将计算结果与钢锚箱静载模型试验结果相比较。结果表明,实体单元加接触单元法计算模型,即用实体单元模拟钢锚箱底部的锚垫板、用空间高阶壳单元模拟锚箱中其他钢构件及主梁、用非线性接触单元模拟锚垫板与承压板间不焊接但紧密压贴的关系,能够较真实、合理地反映钢锚箱的实际受力情况。钢锚箱虽然板件较多,但整体性能好,索力传递流畅,锚箱锚固顶、底板上2条焊缝传递索力,承压板与主梁焊缝主要传递抗弯作用力,因此要保证各板件接触、焊接良好,不能产生大的残余应力和残余变形。随着荷载的增长,钢锚箱高应力区应力增长速度减缓,部分低应力区应力增长加快,这对受载有利。仿真计算时,要注意壳单元角点局部位置可能出现应力计算失真。

3D Finite Element Analysis of Cable-Girder Anchorage Zone for Long-Span Cable-Stayed Bridge

3D nonlinear finite element analyses of steel anchor box used mostly in cable-girder anchorage zone for long-span cablestayed bridge were established by different methods.The calculation results were compared with those obtained from the static test of steel anchor box model.Results show that the method of solid element with nonlinear contact element can represent reasonably the actual working states of steel anchor box.This method can be described that the anchorage frame of steel anchor box is simulated by solid element,else steel slabs and main-girder are simulated by high-order shell element and the state that the anchorage frame and the setting plate are not welded together but only pressed closely to each other is simulated by non-linear contact element.Though there are a lot of slabs,the global behavior of steel anchor box is well and the cable force transfers fluently.The two welding lines on the top and bottom anchor slabs transfers cable force and the welding line between the setting plate and main-girder transfers bending resistance mainly.It should be required strictly that the quality of welding between every slabs is eligible and there are not greater residual stresses and residual deformation. Furthermore,with the increase of cable force,the increase-speed of stress in high-stress area is slower but that in low-stress area is quicker,which is advantageous to resistant cable force.It should be pointed out that the local calculation results of some shell element corners are distortional.