Embedded Plate Anchorage Strength in Precast Hollowcore Slabs

Abstract

In current practice, hollowcore slabs are connected to supporting elements bycasting a headed stud embedment plate in the hollowcore. This provides an area that can be welded to the supporting elements. When the supporting elements consist of foundation retaining walls or exterior walls, load is applied to the supporting element and is transferred to the hollowcore in the form of shear force. The capacity of anchors cast-in concrete can be calculated using design codes for structural concrete; however, these design procedures were developed using experimental data on solid concrete slabs. Due to the longitudinal voids in hollowcore slabs, it is uncertain if the design procedures developed for solid concrete apply to hollowcore. This research aimed to determine the applicability of the current design procedures to hollowcore and provide insight into the anchorage strength of the embedded plate in hollowcore slabs. Experimental testing was performed on hollowcore slabs to establish the anchorage strength in three directions. The results indicated that for the out-of-plane suction direction the headed stud nearest the slab edge may not be effective and the anchorage capacity should be designed using only the headed stud further from the slab edge. Additionally, the breakout strength in this direction should be calculated using a projected failure area that accounts for the longitudinal voids. The predicted failure mode matched the experimental failure mode for most tests, but the experimental capacity varied in comparison to the predicted capacity for the tests.