热弯钢管CFST-外包RC复合节点受力性能

Mechanical performance of hot-bent steel pipe CFST-wrapped RC composite joint

摘要:

为研究某体育馆新型复合节点的受力性能,以该体育馆大跨桁架结构弦杆钢管弯曲后竖直插入地下钢筋混凝土框架柱的拱脚为原型,设计了3个采用热弯圆钢管的CFST-外包RC组合节点,进行了节点在弦杆受压、腹杆受拉的复杂受力下加载试验与有限元数值模拟,研究了热弯钢管残余应力、不同弯曲角度以及弦杆根部钢管内是否填充混凝土等对节点破坏形态、承载能力等受力性能的影响。结果表明: 热弯钢管CFST-外包RC组合节点的破坏形态主要为弦杆根部钢管的屈曲破坏,节点承载力取决于弦杆根部受压承载力；钢管热弯产生的残余应力降低了节点刚度且钢管弯曲角度越大节点刚度降低越大,但对承载力基本没有影响；钢管内填混凝土可以显著提高节点刚度和承载力,节点刚度和承载力随钢管直径增大而增大。

Abstract:

To study the mechanical performance of a new type of composite joint in a gymnasium, we designed three concrete-filled steel tube (CFST)-wrapped reinforced concrete (RC) composite joints using hot-bent steel tubes by taking the arch foot from the gymnasium project as the prototype, in which the long-span truss structural chord steel tube was bent and inserted vertically into the RC frame column. Load test and finite element simulation of the joints were carried out under complex loading with chord compression and web tension. The effects of residual stress, different bending angles, and whether the steel tube at the root of the chord is filled with concrete on the failure forms and bearing capacity of the hot-bent steel tube of composite joints were studied. Results show that the failure form of the hot-bent steel tube CFST-wrapped RC composite joints was mainly the buckling failure of the steel tube at the root of the chord. The bearing capacity of the joint depended on the compressive bearing capacity of the chord root. The residual stress generated by hot bending of the steel tube reduced the stiffness of the joint, and the greater the bending angle of the steel tube was, the less the stiffness of the joints was, but it basically had no effect on the bearing capacity. The stiffness and bearing capacity of the joints were significantly improved by filling concrete in steel tube, and were increased with the increase in the diameter of the steel tube.