不同构造的钢-混凝土组合桁架节点受力性能试验研究

Experimental study on mechanical performance of steel-concrete composite truss joint with different kinds of fabrication

为研究钢-混凝土组合桁架节点受力性能,选取外接式和耳板式两种节点构造形式,设计缩尺比为1∶3的节点试件,对其进行单调加载试验研究,从承载力、变形能力、破坏模式及刚度等方面对比其受力性能。试验结果表明:两种节点形式均具有良好的承载和变形能力,但耳板式节点承载力更高。外接式节点以节点板外露部分的受压屈曲变形和受拉撕裂为主要破坏模式,耳板式节点则以受压腹杆的受压屈曲为主要破坏方式;破坏时,两种节点混凝土弦杆均产生不同程度的开裂。在弹性阶段,两种节点刚度基本相同;屈曲后,外接式节点还能保持一定刚度,耳板式节点刚度下降较快,荷载-位移曲线基本水平。总体上,耳板式节点受力性能优于外接式节点。

In order to study the mechanical performance of steel-concrete composite truss joint,monotonic loading tests on the models of two kinds of joint forms-external and ear plate,with a scale of 1∶ 3 were conducted to compare their mechanical performance in bearing capacity,deformation,failure mode,stiffness and so on. The results show that both of joint forms have good load carrying and deformation capacity. The bearing capacity of ear plate is higher. The external joint fails in compression buckling of the exposed portion of joint plate and tensile tearing; the failure mode of the ear plate joint is that webs buckle under pressure. Chords in these two forms have concrete cracks to different extent. In the elastic stage,the stiffness of two joints is substantially the same; after buckling,external joint can also maintain a certain rigidity while the stiffness of ear plate joint decreases rapidly and its load versus displacement curve is nearly horizontal. It can be concluded that the mechanical performance of the ear plate joint is superior to the external joint.