配置高强抗剪钢筋的混凝土整浇界面直剪性能试验研究

Experimental study on direct shear behavior of monolithically cast concrete interfaces with high-strength shear reinforcements

为研究抗剪钢筋的屈服强度f y和混凝土保护层厚度h对混凝土整浇界面直剪性能的影响,开展了12个Z形试件推出式试验。基于试验现象和界面实测的荷载滑移曲线,提出界面剪力传递机理。根据试件的承载力测试值,对规范ACI、PCI以及AASHTO的界面直剪承载力计算公式进行评估分析。结果表明:当f y由400 MPa提高至600 MPa或h由20 mm增加至40 mm时,界面的直剪强度和刚度均无显著变化,但h的变化会引起界面破坏模式的改变;混凝土的粘结力和内聚力对界面直剪承载力的贡献较大;3个规范的计算公式都能较好地应用于工程设计,但ACI和PCI计算公式过于保守,AASHTO计算公式的计算精度较高。

In order to study the influence of the yield strength f y of the shear reinforcement and the concrete cover thickness h on the direct shear performance of the monolithically cast concrete interface,a push-out test of 12 Z-shaped specimens was carried out.Based on the experimental phenomenon and the measured load-slip curve of the interface,the interface shear force transfer mechanism was revealed.According to the test value of the bearing capacity of the specimens,the calculation formulas of the interface direct shear bearing capacity of the standard ACI,PCI and AASHTO were evaluated and analyzed.The results show that when f y increases from 400 MPa to 600 MPa or h increases from 20 mm to 40 mm,the direct shear strength and stiffness of the interface do not change significantly,while the change of h will cause the different interface failure modes;The cohesive force of concrete has a great contribution to the direct shear bearing capacity of the interface;The three standard calculation formulas can be applied to engineering design,while the ACI and PCI calculation formulas are too conservative,and the AASHTO calculation formula is of great accuracy.