Numerical investigations on non-rectangular anchor groups under shear loads applied perpendicular or parallel to an edge

Abstract

Anchorages of non-rectangular configuration, though not covered by current design codes, are often used in practice due to functional or architectural needs. Frequently, such anchor groups are placed close to a concrete edge and are subjected to shear loads. The design of such anchorages requires engineering judgement and no clear rules are given in the codes and standards. In this work, numerical investigations using a nonlinear 3D FE analysis code are carried out on anchor groups with triangular and hexagonal anchor patterns to understand their behavior under shear loads. A microplane model with relaxed kinematic constraint is utilized as the constitutive law for concrete. Two different orientations are considered for both triangular and hexagonal anchor groups while no hole clearance is considered in the analysis. Two loading scenarios are investigated: (i) shear loading applied perpendicular and towards the edge; and (ii) shear loading applied parallel to the edge. The results of the analyses are evaluated in terms of the load-displacement behavior and failure modes. A comparison is made between the results of the numerical simulations and the analytical calculations according to the current approaches. It is found that, similar to the rectangular anchorages, and also for such non-rectangular anchorages without hole clearance, it may be reasonable to calculate the concrete edge breakout capacity by assuming a failure crack from the back anchor row. Furthermore, the failure load of the investigated groups loaded in shear parallel to the edge may be considered as twice the failure load of the corresponding groups loaded in shear perpendicular to the edge.