节点刚度对外伸端板连接钢框架结构抗连续倒塌性能的影响研究

Study on the influences of joint stiffness on the progressive collapse resistance of structures with extended end plate joints

为研究节点刚度对外伸端板连接钢框架结构抗连续倒塌性能的影响,本文利用ANSYS14.0建立两个6层平面钢框架的有限元模型,梁柱节点分别为刚性节点和半刚性节点,半刚性节点利用非线性弹簧单元Combin 39单元进行模拟。考虑材料非线性及几何非线性,采用备用荷载路径法对其进行非线性静力分析(采用Pushdown analysis)及非线性动力分析。结果表明:柱破坏时,与刚性节点平面钢框架相比,半刚性节点平面钢框架的塑性铰出现较晚,失效点竖向位移增大,结构的竖向承载能力降低,更易发生倒塌破坏,因此,进行外伸端板连接钢框架结构的抗连续倒塌分析时应考虑节点刚度的影响,否则会高估其抗倒塌能力,带来偏不安全的结果。

In order to study the influence of joint stiffness on the performance of anti progressive collapse of steel frames with extended end plate connection,two finite element models of six-story planar steel frames are established by ANSYS14. 0,and the corresponding beam-column joints are rigid and semi-rigid respectively. The nonlinear spring element Combin 39 is used to simulate the semi-rigid connections. Alternative load path method is employed to perform nonlinear static analysis（ using Pushdown analysis） and nonlinear dynamic analysis on the two finite element modes. Compared with planar steel frames with rigid joints, the plastic hinge appears late, the displacement of the failure point increases,and the vertical bearing capacity decreases for the planar steel frame with semi-rigid joints,which is more easy to induce progressive collapse. Therefore,the influence of joint stiffness on the performance of anti progressive collapse of steel frames with extended end plate connection should be considered,otherwise,the unsafe results would be induced.