大跨度铁路钢桁梁斜拉桥带水平K撑桥面系传力特性

在列车制动力等纵向力及竖向荷载作用下的空间变形均会导致钢桁梁桥面系存在复杂的纵向受力和传力,针对大跨度铁路钢桁梁斜拉桥带水平K撑内密肋桥面系,基于解析公式推导、有限元仿真分析研究其受力特性和桥面构件的纵向传力比。在此基础上,基于应力等效准则制作1∶4的试验模型,进行最不利工况下加载试验,研究该桥面系的实际受力和传力特性。结果表明:纵向传力解析式显示,K撑与横梁的纵向传力比仅与结构参数相关,为0.69~2.76的定值,能传递40.83%~73.40%的总纵向力,K撑面积、横梁外伸长度是影响纵向传力比的主要参数;由全桥杆系有限元模型分析的内力结果计算的纵向传力占比介于61.09%~72.53%之间,由局部有限元模型分析的应力结果计算的纵向传力占比介于57.45%~86.60%之间,试验模型实测应力计算的纵向传力占比介于58.16%~87.95%之间,不同方法计算的纵向传力占比存在一定误差,其原因主要源于理论简化、计算模拟及测试误差,但均能反映纵向传力比的基本范围。可见,K撑构件能够有效传递纵向力,降低横梁面外弯矩,改善桥面系结构受力。

Force Transfer Characteristics of Floor System with Horizontal K-Struts in Long-Span Railway Cable-Stayed Bridge with Steel Truss

The spatial deformation under the action of the longitudinal force such as train braking force and the vertical load will lead to the complex longitudinal force and transmission of the floor system with steel truss girder.For the internal multi-ribbed floor system with horizontal K-struts of long-span railway cablestayed bridge with steel truss,the mechanical characteristics of the floor system and longitudinal force transfer ratios of bridge deck members were analyzed through analytical formula derivation and finite element simulation analysis.On this basis,a test model with a scale of 1∶4 was designed according to the criterion of stress equivalence,and the loading tests under the most unfavorable conditions were carried out to study the actual mechanical and force transfer characteristics of the floor system.The analytical expression of longitudinal force transfer shows that the longitudinal force transfer ratio of K-struts to crossbeams is only related to the structural parameters,which is a constant value of 0.69~2.76,and can transfer40.83%to 73.40% of the total longitudinal force.The main parameters affecting the longitudinal force transfer ratio are the area of K-struts and the extension length of beam.The longitudinal force transfer ratio calculated from the internal force results of the finite element model analysis of the whole bridge member system is between 61.09% and 72.53%,and that calculated from the stress results of the local finite element model is between 57.45%and 86.60%,and that calculated from the measured stress of the test model is between 58.16%and 87.95%.There are some errors in the longitudinal force transfer ratios calculated by different methods,which are mainly due to the theoretical simplification,calculation simulation and test errors,but all of them can reflect the basic scope of the longitudinal force transfer ratio.It can be seen that K-struts can effectively transfer the longitudinal force,reduce the out of plane bending moment of the crossbeam and improve the stress of the floor system structure.