Anchor Failure Modes |
(1) Concrete Cone - Concrete cone is characterized by a cone shaped "spall" that forms from the base of the anchor to the surface of the concrete. This failure occurs when the applied forces on the concrete exceeds the tensile capacity of the concrete. The concrete will then crack along the principal tensile zones. These zones typically occur at angles of about 45 degrees of the applied load. This failure can occur with any anchoring system but can be controlled to some extent by proper anchor spacing and edge distance.
(2) Side Blowout - A side blowout is characterized by a concrete spall forming towards the nearest free edge of the concrete. The culprit is generally inappropriate edge distance given to the anchor.
(3) Reverse Concrete Cone - The reverse concrete cone is characterized by the appearance of a cone shaped spall. It is similar to a regular concrete cone except that it occurs on the bottom surface of the base material. If during drilling you approach the opposite side of the surface a cone forms that is approximately two diameters deep. If an attempt is made to install the anchor so that the expansion clip is below this cone, a substantial reduction in anchor capacity will occur.
(4) Steel Failure - A steel or material failure is characterized by little to no slippage, followed by a sudden fracturing of the anchor. This failure usually occurs in the threaded portion of the anchor when the applied loads exceed the material strength. This can occur in either tension or shear.
(5) Pull Through - A pull through failure is characterized by withdrawal of the anchor with little or no damage to the concrete. This failure mode applies only to mechanical expansion anchors and occurs when the clip remains in the hole. this failure occurs when applied forces exceed the frictional expansion force of the anchoring system.
(6) Pullout - A pullout failure is characterized by withdrawal of the anchor with little or no damage to the concrete. The anchor pulls or slips intact from the hole. For a mechanical anchor the expansion clip is pulled out with the anchor body. This failure occurs when the applied force exceeds the frictional expansion force or bond force of the anchoring system.