Expansion bolt assembly

An expansion bolt assembly comprising an axially elongated anchor bolt having a first end and a second end, said anchor bolt includes an axially extending conically shaped expansion head formed on the first end of the anchor bolt with the axially extending conically shaped surface of said expansion head tapering inwardly from the first end toward the second end of said anchor bolt, a shank extending from the smallest diameter end of said expansion head toward the second end of said anchor bolt, and axially extending second end portion of said anchor bolt located between said shank and the second end of said anchor bolt, said second end portion having means thereon for attaching a load to said anchor bolt, an expansion sleeve laterally enclosing said shank and arranged to be expanded by said expansion head, wherein the improvement comprises that said second end portion comprises a plurality of angularly spaced axially extending projections protruding radially outwardly from said shank and being uniformly spaced apart around the axis of said anchor bolt, each said projection having a radially outer axially extending surface, said projections being spaced apart by axially extending indentations coextensive with said projections with said indentations located radially inwardly of said projections, said means for attaching a load to said anchor bolt comprises a thread extending circumferentially around said radially outer surfaces of said projections with said thread interrupted by said indentations, and a nut engageable with said thread for securing a load to said anchor bolt.