方钢管焊接T型节点轴向滞回性能分析

Axial hysteretic behavior of welded steel square tubular T-joints

焊接钢管节点在大跨结构中应用广泛,为评价该类节点的抗震性能,对方钢管焊接T型节点进行了轴向往复加载试验和有限元参数分析.试验表明,焊接节点试件均由于初始裂纹发展形成贯穿裂缝而破坏,受拉开裂会降低节点的延性.节点有限元模拟在破坏形态、滞回曲线和骨架曲线等方面与试验结果吻合较好,等效塑性应变可较准确预测初始开裂位置.参数分析表明,支管-主管宽度比、主管长宽比、主管轴力比等参数对节点滞回性能有明显影响,其中支管-主管宽度比β的影响最大.节点的承载和耗能机制也取决于β,当β较小时以主管上翼缘的弯曲变形控制为主,当β较大时则以主管上翼缘的剪切变形控制为主.尽管往复加载会引起开裂破坏,以规范现有的静力设计公式计算节点的抗震承载力是可行的.

The welded steel tubular joints are widely used in large span structures.To evaluate the seismic behavior of such kind of joints,steel tubular T-joints with square sections under axial cyclic loading were studied experimentally and numerically,respectively.The experimental tests indicate that the failure of the specimens is due to the development of cracks,resulting in the reduction of the joint ductility.The finite element simulation resluts of the specimens are consistent well with the test results in terms of failure modes,hysteretic and skeleton curves.The equivalent plastic strain contour can accurately predict the location of the initial crack.Further parametric studies demonstrate that parameters such as the brace to chord width ratio,the slenderness and the stress ratio of the chord obviously influence the hysteretic behavior of the joints,among which the brace to chord width ratioβplays key role in dominating the loadbearing and energy dissipation mechanisms of the joints.Bending of the chord flange dominates the behavior of joints with smallβ,whereas shear of the chord flange dominates those with largeβ.Other than the cracking phenomenon under hysteretic loading,the static strength calculation methods in current specifications are applicable for predicting the seismic strength of the joints.