ABSTRACT
Kuenzlen & Eligehausen (2002) also noted that the tensile strength of anchors varies proportional to hef1.5. Therefore, by using the effective depth calculated using Equation 1, they adopted Concrete Capacity Method (Eligehausen et al., 2006) to estimate the tensile strength of screw anchors and proposed Equation 2. Concrete Capacity Method was earlier developed to describe the tensile strength of anchor studs, expansion and undercut anchors based on concrete cone failure mode (Fuchs et al., 1995). Equation 2 is valid for screws with a threaded length greater than 0.8hef,
1 INTRODUCTION
Using chemical and mechanical anchors is one of the popular methods of connecting structural components and building services to concrete. Amongst several types of anchors, screw anchors have gained their popularity mainly due to their quick and easy installation and their removal when not required. Even though some of the design standards include design provisions for screw anchors (ACI 318 2008, TS 101 2015), there is little research available on how to estimate the strength of screw anchors (Olsen et al., 2012). The first and most substantial research on screw anchors was carried out by Kuenzlen & Eligehausen (2002) followed by some more recent studies. Kuenzlen & Eligehausen (2002) conducted 500 tests to examine the tensile strength of screw anchors of 8-18 mm diameter and embedment depth of 30-110 mm in concrete of cylinder compressive strength of 25.5 MPa (using a factor of 0.85 to convert the cube strength to cylinder). They found no meaningful correlation between the diameter of anchor and the tensile strength, and the type of thread was found to have only some minor influence on the tensile strength. Furthermore, they observed two failure modes depending on the embedment
and effective depth between 10d0 (where d0 is the screw diameter) and 150 mm.
