方钢管混凝土柱—钢梁外隔板式节点非线性有限元分析

Nonlinear analysis on connection with outer diaphragms between square concrete filled steel tube columns and steel beams

选择合适的材料本构模型,利用三维实体单元,对方钢管混凝土柱—钢梁外隔板式节点建立了同时考虑几何非线性和材料非线性的有限元分析模型,模拟分析了单调加载下节点的受力性能,较为精确地分析了节点区应力分布。结果表明,由有限元模型所得的位移曲线与试验所得的低周反复荷载作用下的骨架曲线极为相似,由有限元模型所得的应变分布和发展规律与试验结果一致。外隔板式节点的梁端弯矩一部分通过柱腹板两侧隔板传递到柱钢管腹板和核心混凝土,另一部分则主要通过柱角两内侧各0.25倍柱宽范围内的隔板直接传递给柱钢管翼缘和核心混凝土,柱角附近的隔板出现严重的应力集中,节点因受压翼缘屈曲、梁翼缘变截面最窄处形成塑性铰而破坏。节点核心区混凝土符合斜压杆受力机制。

Selecting suitable material model, by 3D solid element, the nonlinear FEM models of outer diaphragm connection between concrete-filled square tubular columns and steel beams involving geometric large deformation and material nonlinear is presented. Joint behaviors and stress distribution are analyzed under on monotonic load. The results indicate that the monotonic load-displacement curves, stress distribution and developing from the FEM agree well with framework curves of the cyclic behavior from the low-cycle reversed loading tests. Some of the end moments of benms are transformed to the column tuber web and the core concrete at the panel zone by the outer diaphragm connected to the column web. Others are directly transformed to the column tuber flange and the core concrete by the diaphragm near the column comer. Serious stress concentrate is occurred in diaphragm near the column comer. The specimen is failure because compressed flanges are buckled and the plastic hinges are formed at narrowest section. Diagonal compression strut mechanism is formed in concrete at panel zone.