支座底板直连接型焊接空心半球节点受力性能试验研究及分析

Experimental study and analysis on mechanical behavior of support bottom plate directly connected welded hollow hemisphere joints

为研究支座底板直连接型焊接空心半球节点在受拉压状态下的力学性能,设计制作了8个试件。通过试验和有限元分析方法,获得了节点的破坏模式、荷载-位移曲线和荷载-应变曲线。结果表明,受压工况下试件的破坏模式为半球先屈服支管后屈服、支管屈服和半球表面屈服,受拉工况下为半球先屈服后支管与半球相交处半球表面产生裂纹。节点承载力随半球直径、半球壁厚、支管直径及受力工况的不同而改变,受支管壁厚影响较小。在受力过程中,支管分别承受拉压力的节点试件在支管与半球相交区域的测点最先进入屈服状态,其余加载工况下试件最不利位置均为半球顶部。基于对218个有限元模型在受压和受拉工况下的参数化分析,非线性拟合提出了节点极限承载力计算公式,并考虑了加劲肋对节点承载力的影响,给出承载力提高系数。

To investigate the mechanical properties of support bottom plate directly connected welded hollow hemisphere joints under tension and compression,eight specimens were designed and manufactured.The failure modes,load-displacement curves and load-strain curves of the joints were obtained by test and finite element analysis method.The results show that the failure modes of the specimens under compression condition are hemisphere first yields and the branch pipe then yields,the branch pipe yields and hemisphere yields,while under tension condition,the hemisphere first yields and then cracks appear on the surface of the hemisphere at the intersection of the branch and hemisphere.The joint bearing capacity varies with the hemispherical diameter,hemispherical thickness,branch pipe diameter and stress conditions,and has nothing to do with branch pipe wall thickness.In the process of loading,specimen with branch pipes subjected to tension and pressure respectively first enter the yield state at the measuring point where the branch tube intersects with the hemisphere,and the most unfavorable position of the specimens under other loading conditions is the top of the hemisphere.Based on the parametric analysis of 218 finite element models under compression and tension conditions,the calculation formula for the bearing capacity of the joints was fitted and proposed by nonlinear analysis,and the influence of stiffeners on the ultimate bearing capacity of the joints was considered,the improvement coefficient was given finally.