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为了研究X形方圆交汇钢管节点(主管为方形截面钢管、支管为圆形截面钢管)的焊缝轴拉承载力,对5个非刚性连接和3个刚性连接试件进行静力加载试验。采用硅橡胶印模技术对焊缝几何特性进行精细化测量,考察焊缝全周的应变分布、破坏模式和承载力。试验结果表明:刚性连接试件在轴拉荷载作用下的焊缝全周应变分布均匀,而非刚性连接试件的焊缝全周应变分布则呈现明显的不均匀性;非刚性连接的焊缝承载力相对于刚性连接的焊缝承载力有较大程度的降低,主要原因是焊缝应力的不均匀分布以及热影响区材料的脆性破坏无法与非刚性连接主管管壁的塑性变形协调,从而先于熔敷金属发生断裂。采用有限元分析方法对焊缝的受力性能进行分析,得到不同节点参数下的焊缝有效长度,通过试验和有限元参数分析,提出了基于焊缝有效长度,且满足规范可靠度要求的非刚性连接焊缝轴拉承载力计算式。
In order to study the bearing capacity of the welded joints of X-shaped square intersections of steel pipe joints (whose main pipe is square section steel pipe and branch pipe is circular section steel pipe), five non-rigid connections and three rigid connections were subjected to static loading test. Silicone rubber stamping technology was adopted to measure the geometric characteristics of the weld and to investigate the strain distribution, failure modes and bearing capacity of the whole weld. The experimental results show that the strain distribution of the welded joint under the axial load is uniform, while the strain distribution of the welded joint of the non-rigid specimen shows obvious inhomogeneity. The non-rigid welded joint The main reason for the decrease of the bearing capacity of the welded joints with respect to the rigid connection is the non-uniform distribution of the stress in the weld and the brittle failure of the material in the HAZ, which can not be coordinated with the plastic deformation of the pipe wall of the non-rigid connection Rupture before deposited metal. The finite element analysis method is used to analyze the mechanical properties of the weld. The effective length of the weld under different joint parameters is obtained. Based on the analysis of the experimental results and the finite element analysis, the effective length of the weld is proposed based on the effective length of the weld. Calculation formula of bearing capacity of rigid connection seam.