直接焊接KT型搭接方管节点破坏类型的有限元分析

利用ANSYS程序对KT型搭接方管节点的破坏类型进行了有限元分析，主要分析了支杆与弦杆边长比、弦杆宽厚比、支杆与弦杆厚度比对节点破坏类型的影响。分析得出节点主要发生4种类型的破坏：受拉支杆一侧弦杆上表面局部屈曲破坏；弦杆上表面塑性破坏；受拉支杆强度破坏；弦杆弯曲破坏。弦杆无轴压作用时，弦杆宽厚比、支杆与弦杆厚度比越小节点越易于发生第3类破坏，支杆与弦杆边长比为大值或小值时发生第3类破坏的节点均多于支杆与弦杆边长比为中间值的情况。弦杆有轴压作用时，随弦杆宽厚比、支杆与弦杆厚度比增大，节点由较多发生第3类破坏过渡到第2类破坏，最后到第1类破坏。随着支杆与弦杆边长比增大，发生第1类破坏的增多，支杆与弦杆边长比为0．8的部分节点发生了第4类破坏。

Finite Element Analysis of Failure Modes of Directly Welded KT-type Overlapped SHS Joints

Finite element analysis on the failure modes of the overlapped KT-type square hollow section （SHS） joints was carried out by using ANSYS program. Influences of parameters including side lengh ratio of brace and chord, width-thickness ratio of chord, thickness ratio of brace and chord on the failure modes of joints were mainly analyzed. The analytical educed that the joints were found to fail in four modes. The 1st failure mode was local buckling failure of the upper chord surface behind the tensile brace. The 2nd mode was plastic failure of the upper chord surface. The 3rd mode was strength failure of the tensile brace. The 4th mode was chord bending failure. For joints without chord axis pressure, it is concluded that the joint is prone to fail in the 3rd mode when width-thickness ratio of chord, or thickness ratio of brace and chord is small and more joints with intermediate side lengh ratio of brace and chord fail in the 3rd mode than joints with big or small side lengh ratio of brace and chord. For joints with chord axis pressure, it is concluded that the main failure mode is changing from the 3rd mode to the 2nd mode then the 1st mode when width-thickness ratio of chord, thickness ratio of brace and chord increase and that the 1st failure mode happens more frequently when side lengh ratio of brace and chord increases and that a few joints with side lengh ratio of brace and chord equaled to 0.8 fail in the 4th mode.