Analysis on the tensile strength of post-installed large-diameter anchors in concrete

Abstract

Post-installed large-diameter anchors (PLAs, diameter range: 40mm-150mm) have been widely used in the anchoring of equipment due to their flexible layout. Previous studies on the tensile capacity of PSAs have mainly focused on PLAs with a diameter ranging from 6mm to 36mm, while their formulas for calculating tensile strength have produced great errors as can be seen in their experimental results for large-diameter anchors. To investigate the tensile strength of PLAs, the failure characteristics, ultimate failure loads, loading displacement, and bond stress distribution of PLAs were measured in this study by using 32 full-scale specimens in 8 groups with different anchoring depths and anchor diameters. The full-scale model was applied in an ABAQUS numerical analysis, and the results were compared with the test results. A novel method for calculating the tensile capacity of PLAs was then built while considering both corrected mean bond shearing stress and concrete capacity design (CCD). The results demonstrate that compound bonding failure is the major failure mode of a large-diameter anchor system. Meanwhile, the axial stress of the anchor bolt shows a concave distribution pattern along the anchoring depth. The bond stress of the glue layer conforms to the hyperbolic functional distribution under small loads according to elastic theory but shows an approximately uniform distribution while approaching the ultimate load. Moreover, the bond stress of the glue layer decreases along with an increasing anchor diameter. The results of the finite element simulation conform well to the test results, thereby highlighting the reliability of the proposed calculation method. The conclusions also provide theoretical references for calculating the tensile strength of PLAs.