Erhöhung des Durchstanzwiderstands von Flachdecken durch Verbundeinbauteile aus UHPC

Enhancement of punching shear capacity of flat slabs by built-in UHPC composite elements

A total of nine punching shear tests on interior column-slab connections was performed to investigate the potential enhancement of the shear punching capacity in flat slabs. All test specimens included double-headed studs as punching shear reinforcement. Eight slabs were additionally reinforced in the vicinity of the column by an UHPC unit. These elements were built in around the columns in the slab compression zone, replacing there the normal strength concrete (NSC). UHPC units with two different diameters were applied. Several of these elements were provided with joints and channels for the double-headed studs. The slabs including an UHPC element reached significantly higher failure loads than the test specimens without such an element. In the slabs including the smaller UHPC units, a clear punching shear failure outside the elements was observed. In the case of the larger UHPC units, significant cracks occurred inside the elements, indicating the initiation of a failure of the UHPC.