焊接残余应力对钢桁斜拉桥整体稳定性的影响

Influence of welding residual stress on stability of steel truss cable-stayed bridge

以郑州黄河公路铁路两用桥为背景,建立了桥塔与主桁连接部位的三维有限元模型,考虑材料热物理性能依赖于温度的变化,对桥塔焊趾处典型焊接细节的焊接温度场和焊接残余应力进行数值模拟,分析了焊接残余应力对结构整体稳定性的影响。通过热力学分析模拟焊接过程温度场变化,将冷却温度场作为荷载,通过结构分析计算桥塔与主桁连接处焊接残余应力;经过一定的简化,将焊接残余应力作为初应力施加到结构典型焊接细节上,分析其对钢桁结构稳定承载力的影响。计算结果表明:初应力同时施加于下横梁和中桁架上弦杆时,稳定系数下降13%;故在焊接结构中初应力对稳定性的影响应引起足够重视。

Taking Yellow River bridge in Zhengzhou as an example,the 3D FE model of the pylons-main truss connection joint was built.Regarding the variation of physical properties of materials have relation with temperature,the welding temperature field and welding residual stress at the weld joint of the pylons-main truss connection were modeled with numerical method,the effects of welding residual stress on the stability of bridge were studied.The distribution of temperature during welding process was simulated by thermodynamics analysis,the welding residual stress at the weld joint of the pylons-main truss connection was calculated by regarding temperature field as load.By regarding welding residual stress as initial stress after simplification treatment,the effects of welding residual stress on the stability of bridge were presented.The calculation results show that the coefficient of stability decrease by 13% when initial stress is applied to both bottom cross girders and upper chords of middle truss.Therefore,the effects of initial stress on stability in welded truss bridge should be paid enough attention.