Tensile Behavior and Design of Screw Anchors in Thin Concrete Members

This paper presents an experimental program investigating the behavior of single screw anchors embedded in thin concrete membersunder tension loading. Variables included: concrete thickness, concrete compressive strength, anchor diameter, and anchor manufacturer. Anchors were embedded in the full thickness of the concrete member and the effects of back-face "blowout" due to drilling were considered. The results show that concrete strength, anchor diameter, and anchor brand have a statistically significant influence on the capacity of anchors embedded in 4 in. (102 mm) thick concrete. However, these factors make no significant difference to the capacity of screw anchors in 2 in. (51 mm) thick concretemembers. Based on the experimental results, a behavioral and design models are proposed. These models use a reduced embedment depth to address the back-face concrete blowout due to drilling. The proposed model results in levels of accuracy and variability that are consistent with other types of anchorage and the associated models. Keywords: drilling in concrete; post-installed anchors; sandwich wall panels; screw anchors; thin concrete members.