Mechanical behavior of engineered cementitious composites (ECC) under direct shear is investigated by the double-shear tests. The main test variables are the volume ratio (0%, 1%, 1.5%, 2%) of polyvinyl alcohol fiber and strength grade of ECC. The failure mode, load-slip response and shear mechanism of ECC under direct shear are analyzed and discussed, respectively. The test results indicate that the failure mode, direct shear strength, shear slip and ductility (toughness) are influenced and been improved significantly by the incorporation of fibers. With the compressive strength of ECC increases, the direct shear strength increases but the post-peak ductility decreases considerably. The shear mechanisms of ECC is analyzed according to the failure mode. Based on the typical load-slip curve of ECC under direct shear, a set of size independent toughness indices including the equivalent shear strength and two toughness indices are recommended for evaluating the shear toughness of ECC.

中文翻译：

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工程水泥基复合材料的剪切试验：力学行为和韧性评估

通过双剪切试验研究了工程水泥基复合材料 (ECC) 在直接剪切下的力学行为。主要测试变量为聚乙烯醇纤维的体积比（0%、1%、1.5%、2%）和ECC的强度等级。分别分析讨论了ECC在直接剪切作用下的破坏模式、载荷滑移响应和剪切机理。试验结果表明，纤维的掺入对破坏模式、直接剪切强度、剪切滑移和延展性（韧性）的影响和显着改善。随着ECC抗压强度的增加，直接剪切强度增加，但峰后延展性显着降低。根据失效模式分析ECC的剪切机理。基于ECC在直剪下的典型载荷-滑移曲线，