Shear resistance of UHPC connection for prefabricated reinforced concrete slabs with shear grooves and dowel rebars

The shear resistance of post-cast ultra-high-performance concrete (UHPC) connections for assembled prefabricated normal strength concrete (NSC) slabs having shear grooves and dowel rebars was investigated. The effects of different factors on the failure mode and shear capacity were investigated by direct shear tests of 28 Zshaped specimens. The influencing factors included the groove configuration, lap and anchorage length of dowel rebar (the height of UHPC connection), strength of NSC prefabricated slab, and rebar location. The failure modes, UHPC connection shear-slip behavior, dowel rebar strains, and failure mechanism were analyzed. The results indicated that two major failure modes might occur in UHPC connection, including tensile fracture within UHPC connection and shear fracture of UHPC grooves at UHPC-NSC interface. Generally, a larger UHPC connection and smaller groove key width could lead to failure in UHPC-NSC interface, otherwise in UHPC connection. Failure in UHPC connection could exhibit a relatively larger peak bearing capacity than failure in UHPC-NSC interface, but also larger post-peak degradation. In addition, increasing UHPC groove width, UHPC connection height, and prefabricated slab NSC strength could increase the shear capacity. Calculation methods of the peak and post-peak residual shear load-bearing capacity of UHPC connection under different failure modes were also proposed, exhibiting good agreement with the test results.