UHPC键齿胶接缝直剪性能试验研究

Experimental research on direct shear performance of UHPC keyed epoxy joints

针对目前UHPC键齿胶接缝抗剪性能试验研究仍较为匮乏的现状,文章开展17个UHPC单键齿及多键齿胶接缝试件的直剪试验,主要试验参数包括钢纤维掺量(1%~3%)、键齿深度(40~60mm)及侧向预应力(4~13MPa)等,并研究分析以上参数对UHPC键齿胶接缝直剪性能的影响。直剪试验结果发现,UHPC单键齿胶接缝均表现为阳键齿根部剪断的剪切破坏且侧向压应力对剪切主裂缝角度存在一定影响,而多键齿胶接缝的剪切破坏则主要存在同步和分步剪切破坏两种模式;在侧向应力为4~10MPa时,UHPC单键齿胶接缝的抗剪强度为19.05~33.04MPa,而多键齿接缝的抗剪强度为17.14~22.42MPa;键齿胶接缝的抗剪强度均随UHPC钢纤维掺量的增加而增大,且钢纤维掺量从1%到2%时抗剪承载力提升效果更为明显。此外,基于试验数据提出UHPC多键齿胶接缝的抗剪折减系数及抗剪承载力计算公式;结果表明,UHPC多键齿胶接缝的抗剪折减系数试验平均值为0.85。

Due to the lacking of the experimental work on the shear behavior of UHPC keyed epoxy joint,the direct shear tests of 17 UHPC single-keyed and multi-keyed epoxy joint specimens were carried out to promote the development of experimental research.The experimental parameters included the steel fiber content(1%~3%),the depth of shear key(40 mm~60 mm)and the confining stress(4 MPa~13 MPa).The influence of these parameters on the direct shear behavior of UHPC keyed epoxy joints was analyzed on the basis of the test results.The results indicate that all the UHPC single-keyed epoxy joints exhibit as the shear failure with the male key root shearing off,and the confining stress influences the angle of the main shear crack to some extent.In addition,the direct shear failure of multi-keyed epoxy joints show two modes:the synchronous and the step-by-step shear failure.When the confining stresses in the joints are between 4 MPa and10 MPa,shear strength of the UHPC single-keyed and that of the UHPC multi-keyed epoxy joints are 19.05 MPa~33.04 MPa and 17.14 MPa~22.42 MPa,respectively.The shear strength of keyed epoxy joints increases with the UHPC steel fiber content,especially when the steel fiber content increases from 1%to 2%.Moreover,the shear reduction coefficient and the theoretical formula on the shear bearing capacity of UHPC multi-keyed epoxy joints are proposed based on the test data.And it is concluded that the average shear reduction coefficient of UHPC multi-keyed epoxy joints is 0.85.