方钢管混凝土节点核心区剪切试验及其数值模拟

Shear tests and finite element simulation for panel zone behavior of square concrete-filled tubes

为研究方钢管混凝土节点核心区的受力性能,在分析梁柱节点核心区受力特征的基础上,设计了方钢管混凝土节点核心区的直接剪切试验。试验装置简单,能够确保核心区发生剪切破坏,有效反映其受力特征。通过改变钢材及混凝土的强度、节点几何形状及加载方向等参数,完成了13个方钢管混凝土节点核心区试件的单调和往复剪切加载试验,得到了节点剪切破坏特征、荷载-位移曲线等结果,分析了相关参数的影响。在试验结果的基础上,利用理想弹塑性模型模拟钢材,并利用修正了剪力传递系数的固定角弥散裂缝模型模拟混凝土,提出了适用于一般节点核心区分析的高效精细有限元数值模拟方法。模拟结果与试验结果吻合良好,可为复杂组合结构的非线性分析提供参考。

In order to analyze panel zone behavior of square concrete-filled tubes, direct shear tests for panel zone were designed based on analysis results of actual beam-column connections. This simple test method would lead to clear panel zone failure and reflect its main mechanical features. By changing parameters of loading paths, material properties, panel zone shapes and loading directions, 13 specimens were fabricated and tested with failure modes and load-displacement curves acquired. The influences of different parameters were investigated. A fine finite element model with expansibility was proposed based on the test results. Ideal elasto-plastic model was adopted to simulate steel behavior. The fixed angle smeared crack model with modified shear retention factor was adopted to simulate in- filling concrete behavior. Calculation showed a good consistency with test results and could be applied in non-linear analysis of joints in complex composite structures.