Investigation of pull-through and pullout failure modes of torque-controlled expansion anchors

Torque-controlled expansion (TCE) anchors are common concrete anchors that commonly fail in pull-through (PT) and pullout (PO) modes when installed in deep effective embedment depths. While concrete breakout failure has been adequately researched, no design equation is available to predict the ultimate tensile strength in these failures (N_p). To investigate the PT and PO failure modes, 128 tension tests on TCE anchors from three manufacturers in three diameters were tested in two effective embedment depths per diameter. Also, these tests were simulated by finite element models (FEMs) using ABAQUS. The FEMs accurately identified different failure modes, and the predicted strength agreed well with the N_p test results. Additional FEM results were obtained by a parametric study, which showed that anchor diameter, effective embedment depth, concrete strength, and cone geometry are significant to N_p results. An empirical prediction model for N_p was developed. The model was validated by the test results.