Pullout performance of chemical anchor bolts in fibre concrete

Very little independent research is available on whether adding fibres to the concrete will increase the ultimate stress of the anchor bolt pullout value. Previous investigations have focussed on the anchor and considered the anchor, in terms of dimensions and adhesive agents, but not specifically on the addition of synthetic or steel fibres to concrete. This paper addresses the practical aspect of anchor fixings and means of improving pull out performance, that will reduce the risk of failure for the designer and contractor or allow greater design loads.

This work has examined the pull out force required to cause cone shear failure to unreinforced structural concrete when resin anchor bolts were subject to an axial load. Anchor bolts were fixed in unreinforced plain and fibre concrete of different fibre dosage and type for comparisons to be made. The findings show that when compared to plain concrete increased loads can be transferred to the concrete with the use of fibre technology, when used to reinforce the concrete matrix. When the quantity of steel fibres was increased there was a corresponding increase in the pullout values of the bolts.

Bond, shear and anchorage length are well understood with rebar in concrete, however chemical anchor bolts rely heavily on manufacturers data and this study provides an independent assessment of pull out values in various fibre concrete types based upon concrete shear failure of the concrete.