角钢混凝土黏结滑移性能试验与数值模拟

为研究角钢混凝土界面黏结性能,以黏结长度、保护层厚度、混凝土强度为变化参数,设计了9个角钢混凝土试件。获取了加载端的荷载-滑移曲线,分析了各参数对极限黏结强度的影响; 提出了黏结界面极限黏结强度计算公式并与试验结果进行对比,两者吻合较好; 基于界面库仑摩擦准则和重启动分析技术建立了精细化有限元模型,实现了对黏结界面逐步剥离过程的准确模拟。基于研究参数提出了传递长度的计算公式,并与数值模拟进行了对比,证明了该公式的适用性。结果表明:角钢的肢尖具有强烈的致裂作用,推出过程中裂缝的发展将显著降低黏结强度; 极限黏结强度随混凝土强度提高和保护层厚度的增大而提高,但随黏结长度的增大近似呈线性降低趋势; 加载端荷载-滑移曲线包括化学胶结段、上升段、下降段和残余段4个阶段,各阶段界面黏结机理和黏结应力的组成均不相同; 黏结界面的破损从加载端向自由端逐步扩展,扩散过程中黏结应力的传递长度保持不变。

Experiment and Numerical Simulation on Bond-slip Behavior Between Angle Steel and Concrete

In order to study the interface bond behavior between angle steel and concrete, 9 angle steel concrete specimens were designed with the bond length, protective layer depth and concrete strength as parameters. The load-slip curves at the loaded end were obtained, and the influence of each parameter on the ultimate bond strength was analyzed. The calculation formula for the bond strength of interface was proposed, and compared with the test results, they agreed well with each other. Based on the interface Coulomb friction law and restart analysis technology, a refined finite element model was established to precisely simulate the gradual peeling process of the bond interface. Based on the research parameters, a calculation formula of transfer length was proposed, and compared with numerical simulations, which proved the applicability of the formula.The results show that the tip of the angle steel has a strong cracking effect, and the development of cracks during the pushing process will significantly reduce the bond strength. The ultimate bond strength increases with the increasing of concrete strength and protective layer depth, however decreases approximately linearly with the increasing of bond length. The load-slip curves of loaded end include chemical adhesion section, ascending section, descending section and residual section, and the interface bond mechanism and composition of bond stress are different at each stage. The damage of the bond interface gradually expands from loaded end to free end, and the transfer length of the bond stress remains constant during the propagation.