钢管混凝土桁架弦杆界面传力特性分析

文章采用有限元建模方法分析钢管与混凝土的界面传力特性, 以揭示钢管混凝土桁架弦杆工作机理; 将钢管与混凝土界面状态分为绑定(即界面抗剪刚度无穷大)、光滑(即界面抗剪刚度无穷小)和黏性接触(即界面抗剪刚度有限), 分析钢管混凝土桁架节间内受压上弦杆、受拉下弦杆钢管与混凝土的轴向应力、界面剪切应力及剪力传递长度。结果表明: 不同界面状态下钢管轴向应力、界面剪切应力差异较大; 黏性接触最接近钢管与混凝土界面真实工作状态, 弹性工作状态下, 剪力传递长度保持为常数, 与轴力无关; 剪力传递长度范围内钢管和混凝土轴向应力、界面剪切应力沿桁架节间长度方向呈指数函数分布, 剪力传递长度范围外钢管、混凝土轴向应力保持不变。研究结果可为钢管混凝土桁架桥强度、刚度计算及节点构造设计提供依据。

The finite element analysis was used to analyze the interfacial force transfer characteristics of concrete and steel tube to reveal the working mechanism of concrete-filled steel tubular truss chord. The interface states between steel tube and concrete were simulated as tie behavior which means that the interfacial shear stiffness is infinite, smooth behavior which means that the interfacial shear stiffness is infinitesimal, and cohesive behavior which is related to the bond and slip. The axial stress, interfacial shear stress and shear transfer length of concrete and steel tube in compression chord and tension chord were analyzed. The results show that the axial stress and interfacial shear stress of steel tube are different under different interface states. The cohesive behavior is closest to the real working state of the interface between steel tube and concrete. In the elastic working state, the shear transfer length remains constant and is independent of the axial force. The axial stress and interfacial shear stress are exponentially distributed along the length direction of the chord within the range of shear transfer length, while the axial stress of steel tube and concrete remains unchanged outside the range of shear transfer length. The results of the study can provide a basis for strength and stiffness calculation. tions and node configuration design of concrete-filled steel tubular truss bridges.