Test study on anchorage and lap splicing performance of rebars in UHPC
To study the bonding performance between ultra-high performance concrete(UHPC)and rebars,45 direct pull-out specimens and 39 lap-splicing specimens containing new and old UHPC interfaces were designed.The effects of rebar diameter,UHPC cover thickness,anchorage and lap splicing length,loading form,stirrup configuration and interface treatment on the bonding performance were studied through pull-out tests and lap-splicing tests.The results show that for anchorage specimens,the failure mode and bonding strength are mainly influenced by the cover thickness and anchorage length.When cover thickness is less than 3d(d represents the diameter of rebar),all specimens exhibit UHPC splitting failure,and the bonding strengths are relatively small.When cover thickness reaches 3d or above,specimens with the anchorage length of 5d show pull-out failure after rebar yielding,resulting in a higher bond strength.When the anchorage length reaches 10d or more,all specimens fail in the fracture of rebar,and the average decrease of bonding strength is more than 50％.For lap-splicing tests,specimens without stirrups all exhibit interface splitting failure.For specimens with volumetric stirrup ratio no less than 0.2％,bonding performance is mainly influenced by lap splicing length.When the lap splicing length is longer than 6d,the failure mode changes from pull-out failure to fracture of rebar,and the bond strength significantly decreases.Based on the test results,it is recommended that the UHPC cover thickness should be within the range of 3d-5d for pull-out specimens.Besides,design formula of the minimum anchorage/lap splicing length is proposed and recommended values of the critical bonding length coefficient are given.
ultra-high performance concreterebaranchorage and lap splicing lengthbonding performancebonding strength
国家科技期刊平台
NSTL
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