钢管混凝土K型相贯节点试验研究与数值模拟

从钢管混凝土格构式风电塔架原型中取出节点模型,对5个K型焊接相贯节点进行了试验研究和理论分析,研究了不同几何参数条件下节点的破坏过程和特征、荷载-变形关系和承载能力等。建立了有限元模型,分析了各研究参数对节点破坏形态和极限承载力的影响规律,得到了节点失效机制的判别参数与准则。试验结果表明:圆钢管混凝土K型相贯节点在丧失承载力前弦杆的宏观变形特征不明显,腹杆失效是主要破坏形态;与空心圆钢管相贯节点相比,刚度大大增加,相贯线周围应力集中程度也降低。有限元分析结果表明:圆钢管混凝土K型相贯节点的控制破坏形态包括腹杆失效和弦杆冲剪破坏,控制破坏类型的关键指标是腹杆与弦杆的壁厚比τ和夹角θ。为避免钢管混凝土格构式风电塔架出现节点失效,须限制参数τ、θ的取值。本文建议τ≤1,θ≤45°。

Experimental study and numerical simulation for the concrete-filled steel tubular K-joint

Five tubular welded K-joints in lattice concrete-filled steel tubular(CFST) wind turbine generator tower were tested and theoretically investigated, the failure process and characteristics, load-deformation relationship and bearing capacity of the joints under different geometric parameters are studied. A FEA model is built, the influences of all the research parameters on the failure mode and ultimate bearing capacity of this kind of joint are analyzed using the finite element method, the discriminant parameters and criteria of the failure mechanism for this joint are obtained. Experimental results show that for the concrete-filled circular steel tubular(CFCST) K-joint, the macroscopic deformation characteristics of the chord member are not obvious until the joint reaches the ultimate bearing capacity, and the failures mainly occur on the web members, the stiffness of the CFCST joint greatly increases and no significant stress concentration is observed around the intersecting lines compared with the hollow circular steel tubular(HCST) joint. It is found by the finite element analyses that the main failure modes for the CFCST K-joint include the failure of web members and the punching shear failure of chord member, and key factors to control failure modes mainly depend on the thickness ratio τ and the angle θ between web members and chord member;the existing bearing capacity calculation method corresponding to the punching shear failure for the HCST joint is not suitable for the CFCST joint. In order to avoid the occurrence of joint failure in lattice wind turbine generator tower, the τ and θ should be limited. This paper suggests that τ≤1 and θ≤45°.