大跨度钢-混凝土组合桁架铁路桥端节点模型试验研究

钢-混凝土组合桁架梁上弦端节点受力复杂,有必要通过模型试验对其钢-混上弦节点的应力应变状态及工作性能进行研究,探索组合桁架上弦节点合理构造和承载力。介绍节点模型的设计、加载过程和测点布置等;重点通过对试验结果分析和有限元计算的比较,得出弦杆应变和节点板应力的分布规律,通过绘制弦杆荷载-水平位移曲线,对节点的非线性受力行为进行研究,得出节点整体的受力性能。研究表明:钢-混凝土组合桁架节点受力合理,节点承载力安全储备较高,满足铁路桥梁设计要求,PBL连接件抗剪能力良好;节点板是受力的关键部位,加设节点板加劲肋可以有效提高节点屈服后强度,但对极限荷载的提高作用不大。

Model test for the end joint of long-span steel-concrete composite truss railway bridges

Performance of the joints in top chord of a steel-concrete composite truss is unclear and complicated.It is necessary to experimentally study the total joint mechanical properties.The model design,loading process and the arrangement of the measuring points are introduced in this paper.The focuses are the chord strain and joint plate stress distribution,and nonlinear mechanical behavior of the joints,through analysis of load-displacement curves of chord.The results show that the steel-concrete composite joint possesses rational load transfer capability,good ductility,and the PBL connector has a good ability of shearing resistance,the joint plate is the key to the joint.Strengthening the plate with stiffeners can improve the yield load,but is less effective on the ultimate load.