Anchor Pull Out
Pull out of the anchor will indicate that the applied force has exceeded the frictional or compressive force between the anchor and the base material. This mode
of failure is usual when the anchor is unable to transfer the load to develop the strength of the base material. The mode of failure is rarely influenced by
a change in the anchor bolt material.
Anchor Material Failure
Anchor bolt failure indicates that the frictional force of the anchor exceeds the tensile strength of the bolt. This mode of failure is dependent on both
the tensile strength of the bolt material and the strength of the base material.
Base Material Failure
When the applied load is greater than the strength of the base material the material fails. In concrete a shear cone will be pulled usually for anchors installed
at shallow embedment of 4-5 anchors diameters. The angle of the shear cone is assumed to be 45° but can vary up to 60° depending on the type anchor and depth
Space or Edge Failure
Edge failure or coning of the base material will indicate that the base material strength has been exceeded. This mode is usual for shallow embedment or anchors
set too close together. To attain the published pullout values it is recommended that anchors be spaced no closer than six anchor diameters to the edge and
12 anchor diameters from each other. The spacing and edge distance of installed anchors will affect the mode of failure and ultimate load capacity. Anchors
spaced close together or close to the edge of the concrete must have the loading be reduced to compensate.
Base Material Splitting
Concrete or masonry units must be of sufficient size to prevent cracking or splitting during anchor installation or loading. It is also important that the
correct anchor be chosen to prevent this from occurring.