基于有限元方法的复合钢混凝土桥梁热点应力分析研究

通过建立复合钢混凝土疲劳危险部位焊接构件的三维有限元模型,围绕桥梁交通荷载作用下局部热点应力和疲劳损伤累积进行分析,获得合适的在役钢-混凝土桥梁关键焊接构件的疲劳损伤评价方法。研究结果表明:采用大桥有限元模型进行动力特性分析,模型计算固有频率和实测值最大误差在10%以内,计算的动力特性和设计测试阶段特性相符;钢混凝土桥梁纵向加劲桁架细节热点应力区域出现在上下弦杆与对角撑、盖板连接处,与焊缝构件最大疲劳损伤位置一致,主梁框架热应力出现在靠近公路外侧梁腹板连接处;通过线性米勒准则获得的疲劳损伤累积呈线性变化,在高周疲劳损伤初期损伤率增长较慢,后期较快,适用于在役结构疲劳寿命评价。

Research on Hot Spot Stress Analysis of Composite Steel Concrete Bridge Based on Finite Element Method

In this paper,the three-dimensional finite element model of welded members in fatigue dangerous parts of composite steel concrete is established,and the local hot spot stress and fatigue damage accumulation under traffic load of bridges are analyzed,and a suitable fatigue damage evaluation method for key welded components of steel-concrete bridges in service is obtained in this paper.The results show that the maximum error between the natural frequency and the measured value of the model is less than 10%,and the calculated dynamic characteristics are consistent with the characteristics of the design and test stage.The hot spot stress area of the longitudinal stiffening truss of steel concrete bridge appears at the connection between the upper and lower chords and diagonal braces and cover plates,and the results show that the maximum error between the calculated natural frequency and the measured values is less than 10%,and the calculated dynamic characteristics are consistent with those of the design test stage.The maximum value of fatigue damage of weld members is consistent,and the thermal stress area of main beam frame is close to the web connection of side beam outside the highway;The fatigue damage obtained by the linear Miller criterion is linear,and the calculated results are safe and suitable for structural fatigue design.The cumulative initial damage rate of high-cycle fatigue damage increases slowly and quickly in later stage,which is applicable to fatigue life evaluation of in-service structures.