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

(1)混凝土节点抗剪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抗剪粘结性能影响的试验方法。本文采用斜缝矩形试件的单轴压缩试验，在接缝处产生正应力和剪应力。关节的角度改为45至60度。结合最大载荷、载荷-位移曲线和断裂能（载荷-位移曲线下的面积）可以有效地评价接头表面处理对剪切粘结性能的影响。关节面角度以60 °为最佳。(2)混凝土龄期、浇筑方向及水环境下接缝粘结破坏的影响本文研究了水对混凝土接缝在静载和反复荷载作用下粘结性能的影响， 关于我们 调查过了对粘结性能与龄期和新浇混凝土浇筑方向的关系进行了讨论，发现在竖向接缝的情况下，接缝处的粘结强度和新浇混凝土的抗拉强度在上部均小于下部。接缝处粘结强度的降低程度大于新拌混凝土的抗拉强度。(3)采用预制混凝土模板对钢筋混凝土梁进行了弯曲试验研究。研究了PCF与基体混凝土界面粘结性能对梁弯曲破坏行为的影响。结果表明，界面处的拉伸粘结强度和断裂能共同影响沿着界面的裂纹形态，而PCF的刚度则影响裂纹区的大小。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