Some Factors Which Influence the Strength of Bolt Anchors in Concrete


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Title: Some Factors Which Influence the Strength of Bolt Anchors in Concrete

Author(s): Robert F. Adams

Publication: Journal Proceedings

Volume: 52

Issue: 10

Appears on pages(s): 131-138

Keywords: no keywords

Date: 10/1/1955

Many types of anchoring devices are used to anchor conduit, machinery, fixtures, etc., to concrete. This paper describes pull-out tests made with the type known as multiple expansion unit bolt anchors. Best results are attained when the bolt anchors are set in a well-cleaned hole of the proper size and depth. The hole should be drilled with a drill which leaves a rough surface. The depth of the holes should be at least four times their diameter, and they could be placed at least two or three times their depth away from an edge or corner of the concrete if possible. Two anchor units are sufficient for bolt anchors using bolts less than 3/4 in. in size, and three units should bc used for those 3/4 in. or larger. If the anchorage is to take shearing loads, the annular space around the bolt above the anchor units should be filled with a rigid material to support the bolt when a shearing load is applied.