聚乙烯醇纤维改性高延性混凝土双面剪切试验及剪切韧性评价方法

为研究高延性混凝土（HDC）的剪切性能并评价其剪切韧性，设计了5组HDC试件、1组HDC基体试件（不含纤维）和1组普通混凝土对比试件，通过双面剪切试验，以纤维体积分数和HDC抗压强度为参数，分析其破坏形态、抗剪强度及峰值变形，根据试验结果提出了HDC的剪切韧性评价方法。结果表明:HDC纤维桥联作用及纤维拔出过程中吸收了大量能量，试件发生具有延性特征的剪切破坏；与基体试件和普通混凝土试件相比，HDC试件的抗剪强度和峰值变形均显著提高，其提高幅度随纤维体积分数的增加而增大；随HDC抗压强度的增大，试件抗剪强度增大，峰值变形降低；采用初始能量密度和残余剪切韧度比评价HDC的剪切韧性，其剪切韧性显著高于基体和普通混凝土。 

Double shear experiment of highly ductile concrete modified by polyvingl alcohol and shear toughness evaluation method

In order to study the shear property and shear toughness evaluation method of highly ductile concrete(HDC), 5 sets of HDC specimens, 1 set of matrix specimens(without fiber) and 1 set of concrete specimens were designed for comparison. Through double shear experiment, fiber volume fraction and HDC compressive strength were set into parameters to analysis the modes of shear failure, shear strength of HDC specimens and deformation at peak load. Based on the results of experiment, shear toughness evaluation method of HDC double shear experiment was built. The research shows that: with the bridging action of fiber in HDC and during fiber pull-out, it has absorbed considerable energy. The shear failure mode of HDC specimens is ductile failure;Compared with concrete and matrix specimens, the shear strength and the deformation at peak load of HDC specimens are substantially improved, and its range of improvement increases with the increasing number of fiber volume fraction;With the increasing of HDC compressive strength, the shear strength of the HDC specimens increases gradually, and the shear deformation at peak load decreases gradually;Using initial energy density and residual shear toughness ratio to evaluate the shear toughness of HDC materials, the shear toughness of HDC specimen has a significantly higher level than concrete and matrix specimens.