方钢管混凝土柱-钢梁竖向加劲肋式节点非线性有限元分析

Nonlinear finite element analysis on connection with vertical stiffener between concrete filled square steel tube columns and steel beams

对方钢管混凝土柱-钢梁竖向加劲肋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相符,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;竖向加劲肋式节点的梁端弯矩一部分通过竖向加劲肋传递给柱钢管腹板和核心混凝土,另一部分梁端弯矩由梁端翼缘直接传递给柱钢管翼缘和核心混凝土;节点的破坏模式为梁翼缘变截面最窄处形成塑性铰,最终梁受压翼缘出现严重的局部屈曲,而柱钢管和竖向加劲肋均在弹性范围内工作,很好地实现了强柱弱梁、强节点弱构件的抗震原则;节点核心区混凝土性能符合斜压杆受力机制.

The nonlinear finite element analysis （FEA） models of vertical stiffener connection between concretefilled square tube columns and steel beams, considering large nonliear geometric deformation and material nonlinear property were presented. Joint behaviors and stress distribution under the monotonic load were analyzed. The results indicate that the monotonic load-displacement curves, stress distribution and its development obtained from the FEA agree well with framework curves of the behavior from low-cycle repeatedly loading tests. Some of the beam end moment was partially transformed to the column tube web and the core concrete by vertical stiffener. Other part of moment was directly transformed to the column tube flange and the core concrete. The specimens were failure because compressed flange was seriously buckled and the plastic hinges were formed at the weakest section. But the steel tube and vertical stiffener all still worked in elastic state. At that moment, the anti-scismic stracture design crete ＂strong colum and weak beam＂ and＂ strong joint and weak structure element＂ is well achieved. The conavior in joint core under loading can follow the diagonal compression strut working mechanism.