ECC双轴压力学性能及破坏准则试验研究

利用真三轴液压伺服试验机,对3种强度的高延性纤维增强水泥基复合材料(Engineered CementitiousComposites,ECC)进行了双轴压试验研究,得到了ECC在双轴压应力状态下的破坏形态、极限强度和应力-应变曲线,并与普通混凝土的试验结果进行对比,分析了不同应力比下ECC的破坏机理和主压强度的变化规律。试验结果表明,双轴压应力状态下,ECC强度包络线与普通混凝土有一定差别,强度较低时两者结果相近,但强度较高时相同应力比下ECC主压强度增幅明显小于混凝土。最后,基于Kupfer等建立的普通混凝土的强度准则和试验结果,提出了ECC的双轴压强度破坏准则。

EXPERIMENTAL STUDY ON MECHANICAL BEHAVIORS AND FAILURE CRITERION OF ENGINEERED CEMENTITIOUS COMPOSITES UNDER BIAXIAL COMPRESSION

An experimental investigation was conducted to characterize the mechanical behaviors and failure criterion of engineered cementitious composites (ECC's) subjected to biaxial compression by using a triaxial electro-hydraulic servo test system. ECC cubic specimens with three different strength grades were tested in the experiments. The failure modes, ultimate strength and stress-strain curves of ECC's under biaxial compression were obtained and compared with those of conventional concrete. Then, the failure mechanism and variation law of principal compressive strength were analyzed. The test results demonstrated that the strength envelope curves of ECC's were different from the curves of conventional concrete under biaxial compression. The strength envelope curves of the two kinds of materials are close when the strength is low. But with increasing strength, the increase of principal compressive strength of ECC's was apparently less than that of ordinary concrete. Finally, based on the Kupfer's strength criterion for conventional concrete and test results, a novel failure criterion was proposed for ECC materials under biaxial compression.