上承式铁路桁架桥桥面系纵梁疲劳强度的研究

本文对单线铁路上承式栓焊桁梁桥面系纵、横梁的疲劳行为进行了综合分析和研究．通过模型试验和理论分析，探索桥面系结构及其连接的受力状况和应力分析。明确桥面系在不同荷载作用下，鱼形板的受力状况，进一步研究影响其结构疲劳的主要因素，观察疲劳裂纹产生的部位，分析造成结构疲劳和断裂的成因；指出纵梁可按弹性支承连续梁计算；纵、横梁连接处纵梁腹板间隙处将产生面外变形，此面外变形与焊接残余应力、局部焊接缺陷共同作用，容易造成焊趾处开裂；由于构造细节的不同时结构耐劳强度会产生较大影响．试验表明，影响疲劳强度的主要因素是作用应力的脉动量、受力次数和细节式样。提出改进桥面系连接构造的建议，供设计时参考。

Fatigue Strength Research of Longitudinal Girder in Deck truss Bridge

To investigate the fatigue behavior of deck constrction of deck truss,threereduced scale specimens are tested;stress range and type of detail were the two test parameters.The major factors governing fatigue strength are the applied stress range,the numberof cycles,and type of detail.It is found that fatigue cracks commence at some initial discontinuity in the weldment or at the weld periphery,and grow perpendicular to the appliedstresses.It is also found that fatigue strength is very lower without tighfly withstood at cantileverbracket and filler plate.Stringer is calculated according to elastic support continuous beamtheory.