反复荷载下钢管单插板T型节点承载力特性试验及模拟

Experiment and Numerical Analysis on Bearing Capacity Behavior of T-joint with Tube-gusset Plate Connections Under Cyclic Load

结构简单、安装便捷及传力明确的钢管单插板T型节点已广泛应用于特高压及大跨越输电塔等钢管结构,节点设计基本仅限于单调受力强度,而未考虑反复荷载下承载力特性。开展2个不同主管规格单插板T型节点反复加载试验,考察反复荷载作用下单插板节点的承载力–变形滞回特性、破坏模式及影响因素。加载初期T型单插板节点承载力–位移呈线性关系,滞回环所围面积很小,耗能不明显;当达到屈服承载力后节点受压承载力增长缓慢,受拉承载力增长较快,T型单插板节点滞回环所围面积明显增大并较为饱满,呈现出良好的耗能特性;由于节点板与钢管焊接处钢管反复内凹外凸,塑性变形较大,加载结束时主管沿节点板焊缝边发生局部屈曲破坏。开展反复加载承载力特性的数值分析,承载力–变形特性与试验结果接近,非线性模拟分析揭示了反复荷载下单插板节点荷载–变形滞回特性。通过对节点拉压承载力的理论分析,提出合理的设计建议。

T-joint with tube-gusset plate connection,which is a simple,clear-force and easy-install structure,and widely used in UHV transmission towers. But the design of T-joint is basically limited to monotonous load nowadays,without considering the bearing capacity under cyclic loads. Two tests of T-joints with different tube dimensions under cyclic load are performed to study the load-displacement hysteretic behavior,failure modes and effect factors. The test results show that the load-displacement curve of T-joint is linear in the initial of cyclic loading. The area of the hysteresis ring is small and energy consumption is not obvious. The compression load of the T-joint increases slowly,and the tension increases rapidly after the load is up to the yield capacity. It means that the energy dissipation of T-joint is good. The phenomenon of concave inside and convex outside on the steel tubes repeatedly occurs under cyclic load,and the steel tubes are plastically deformed and local buckled after loading.The FEA( finite element analysis) and experimental results are similar so that the nonlinear FEA can be used to analyze the hysteretic behavior of T-joint with tube-gusset plate connection under cyclic load. Based on the analysis of the tension and compression bearing capacity theory of T-joints,some reasonable design suggestions are put forward.