Numerical Investigations on Non-Rectangular Anchor Groups under Shear Loads Applied Perpendicular or Parallel to an Edge

Akanshu Sharma,Boglárka Bokor

doi:10.3390/civileng2030038

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.

Highlights

The current standards and guidelines for the design of anchorages in concrete construction such as EN1992-4 [1], ACI 318 [2], or fib Bulletin 58 [3] provide direct design guidance only for anchor groups with rectangular anchor pattern and maximum three anchors in a row
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
The shear load vs. displacement curve obtained from numerical analysis fo curve shows a typical concrete edge breakout dominated load-displacement r characterized by an ascending branch, a relatively sharp peak followed699 by a grad scending branch

Summary

Introduction

The current standards and guidelines for the design of anchorages in concrete construction such as EN1992-4 [1], ACI 318 [2], or fib Bulletin 58 [3] provide direct design guidance only for anchor groups with rectangular anchor pattern and maximum three anchors in a row. This is primarily due to the fact that the current provisions for the design of anchorages are based largely on semi-empirical formulations and must be limited to the scope of the tests they are calibrated and validated for [4]. For the anchorages where the shear load is applied parallel to the edge or inclined to the edge, a modification factor is used to calculate the resistance [1,6]

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