钢桥面板疲劳热点应力计算模型精度分析

Analysis on precision of hot spot stress calculation model of steel bridge deck weld fatigue

通过建立钢桥面板顶板与U肋焊缝分析模型,考虑不同的单元类型和单元划分精度,计算钢桥面板顶板表面及沿厚度方向的应力分布,分析了不同计算模型精度对应力分布规律的影响,并对比不同热点应力取值方法的计算结果。分析表明:应力集中在焊缝边缘位置表面处最明显,当分析模型单元尺寸足够小时,计算结果收敛。对于顶板焊缝数值计算模型,建议采用8节点实体单元计算热点应力时,板厚方向设置不少于8层单元,采用20节点实体单元计算热点应力时,沿板厚方向设置不少于4层单元。对比几种热点应力取值方法计算结果,不同方法热点应力值相差在10%以内,表面外推法计算结果最大,1 mm方法计算结果最小。

The steel deck roof and U-type rib weld analysis model was established to calculate the stress distributions on deck roof surface and in the thickness direction. The element type and the element mesh an different accuracies were considered. The influence of the accuracy of different calculation models to stress distribution was analyzed and hot spot stress results by different calculated methods were compared. It showed that the stress concentration at the edge of the weld surface location was the most obvious.The stress calculation convergence was gained when the model was divided into enough small units. For the details of deck weld, in the thickness direction, more than 8 layer units were adopted when using 8 node solid element in the model, while more than 4 layer units were adopted when using 20 node solid element in the model.From the comparison results ,the hot spot stress value by different methods was within 10%. The calculation result from surface extrapolation method was maximum while the calculation result from 1 mm method was the lowest one.