Concrete cone failure

The failure is governed by crack growth in concrete, which forms a typical cone shape having the anchor's axis as revolution axis.

Under tension loading, the concrete cone failure surface has 45° inclination.

A constant distribution of tensile stresses is then assumed.

- Cone's projected area Under tension loading, the concrete capacity of a single anchor is calculated assuming an inclination between the failure surface and surface of the concrete member of about 35°.

- Concrete compressive strength measured on cubes [MPa]

- Embedment depth of the anchor [mm] The model is based on fracture mechanics theory and takes into account the size effect, particularly for the factor

[3] Current codes take into account a reduction of the theoretical concrete cone capacity

considering: (i) the presence of edges; (ii) the overlapping cones due to group effect; (iii) the presence of an eccentricity of the tension load.

[4] The tension failure loads predicted by the CCD method fits experimental results over a wide range of embedment depth (e.g. 100 – 600 mm).

[2] Anchor load bearing capacity provided by ACI 349 does not consider size effect , thus an underestimated value for the load-carrying capacity is obtained for large embedment depths.

An increase of the anchor's load-carrying capacity is observed .

[5][6] Anchors, experimentally show a lower load-bearing capacity when installed in a cracked concrete member.

The reduction is up to 40% with respect to the un-cracked condition, depending on the crack width.

[7] The reduction is due to the impossibility to transfer both normal and tangential stresses at the crack plane.