Test Methods for Shear Failure Behavior and for Bond Performance in Water of Concrete Joints and Numerical Analysis

(1)混凝土节点剪切作用下的断裂行为及粘结性能试验方法研究了节点表面处理程度对混凝土节点剪切粘结性能影响的试验方法。我们对具有斜节理的矩形试件进行单轴压缩试验，在节理面上产生法向应力和剪应力。关节的角度改为45到60度。关节表面处理的程度是不同的。结合最大载荷、载荷-位移曲线和断裂能（载荷-位移曲线下面积）可有效评价节理表面处理对剪切粘结性能的影响。结合面的最佳角度为60°。(2)混凝土龄期、浇筑方向与水中接头粘结断裂的影响。本文研究了静荷载和重复荷载作用下，水对混凝土接头粘结性能的影响。讨论了新混凝土粘结性能与龄期和浇筑方向的关系。竖缝试件接缝处的粘结强度和上部新混凝土抗拉强度均小于下部。接缝处粘结强度的降低程度大于新混凝土抗拉强度的降低程度。(3)预制混凝土形式钢筋混凝土梁的弯曲破坏特性进行了预制混凝土形式钢筋混凝土梁的弯曲试验。研究了PCF与基板混凝土界面粘结性能对梁弯曲破坏行为的影响。通过刚体-弹簧网络（RBSN）对试验结果进行了模拟。数值结果表明，沿界面的裂纹形态受界面处的拉伸结合强度和断裂能的影响，裂纹区大小受PCF刚度的影响。少

(1) Fracture Behavior of Concrete Joints under Shear and Test Methods for Bond PropertiesThe test method for evaluating of the effect of degree of joint surface treatment on the shear bond properties of concrete joints was investigated. We adopted the uniaxial compression test on rectangular specimens having slant joint, where the normal and shear stresses were generated at the joint surface. The angles of the joints were changed to be 45 to 60 degrees. The levels of joint surface treatment were varied.The combined use of the maximum load, the load-displacement curves and the fracture energies (area under the load-displacement curves) was efficient to evaluate the effects of joint surface treatments on the shear bond properties. The best angel of the joint surface for the evaluation was 60 degrees.(2) Effects of Age and Casting Direction of Concrete and Bond Fracture of Joints in WaterThe effects of water on the bond properties of concrete joints under static and repeated loads were in … More vestigated. The relations between the bond properties and the age and the casting direction of new concrete were also discussed.In the case of specimens with a vertical joint, both the bond strength at joint and the tensile strength of new concrete at upper parts were smaller than those at bottom parts. The degree of the reduction in the bond strength at joint was heavier than that in the tensile strength of new concrete.(3) Bending Failure Behavior of RC Beams with Precast Concrete FormThe bending tests on reinforced concrete beams with a precast concrete form (PCF) were carried out. The effects of bond properties at the interface between the PCF and substrate concrete on the bending failure behavior of the beams were investigated. The test results were simulated through Rigid-Body-Spring Network (RBSN)It was seen from the numerical results that the crack patterns along interface were affected by both the tensile bond strength and the fracture energy at the interface and that the size of cracked zone was affected by the stiffness of the PCF. Less