Wedge anchors, also known as expansion bolts and expansion anchors, secure themselves using a mechanical wedging effect at the end of the fastener. As shown in the figure, tightening the bolt results in a wedge being driven up against a sleeve. This jams the end of the bolt, and provides the strength. Many different manufacturers provide a variation on this theme, usually depending on the condition of the concrete, and the type of load. If a mechanical anchor fails, it is usually in the form of pulling out a wedge of concrete, and for this reason, proper design looks at the depth of embedment, and assures that the bolts are not spaced too closely. In many parts of the world seismic anchors are another specialized subject. A specialized form of the anchor bolt is the rock bolt, used in rock excavations.
There are three basic styles of wedge anchors, fully threaded, partial threaded and the full-bodied wedge anchor.
Read more about this topic: Anchor Bolt
Famous quotes containing the words wedge and/or anchors:
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—Ernest Becker (1924–1974)
“The primary function of myth is to validate an existing social order. Myth enshrines conservative social values, raising tradition on a pedestal. It expresses and confirms, rather than explains or questions, the sources of cultural attitudes and values.... Because myth anchors the present in the past it is a sociological charter for a future society which is an exact replica of the present one.”
—Ann Oakley (b. 1944)