A Plate Type Edge-Lift Anchor: Shear Reinforcement Influence on Failure Loads

Abstract

The published standard [1] and Industry code of precast practice [2] do not provide a recommendation for calculating the shear capacity of edge-lifting anchors (which are normally placed in the edge of thin wall elements) and are commonly used in the precast industry throughout Australia. These anchors experience loads under tension or combined tension and shear during the lifting process. A load applied perpendicular to an anchor is commonly referred to as a shear load. When a shear load is applied, the anchor reinforcement, typically a shear bar, will provide the majority of the concrete breakout strength. This paper is an evaluation of anchor shear reinforcement test data for edge lift plate anchors in thin walled elements. References and comparisons are made with the formula in ACI 318M-08 [3], which was developed for cast-in anchors, and comparisons of the predicted capacity and the tested shear concrete breakout capacity of the edge lift anchors, with shear reinforcement, is made. Data is presented on 137 tests; the variables tested include concrete compressive strength at time of testing, anchor width, panel thickness, shear reinforcement embedment depth and shear reinforcement diameter. What this paper shows is that the mechanical interactions of a typical shear bar design does behave in a way that can be suitably predicted by the model presented in ACI318M-08 D5.2. This paper examines the failure mechanisms of a typical shear bar and highlights potential installation issues.