Bridges

Bonded anchors are also known as bonded fasteners or chemical anchors are often used to connect structural elements and non-structural elements to structural components. The embedded metal part may be a threaded rod, deformed reinforcing bar, internally threaded sleeve or other shape made of carbon steel, stainless steel, galvanised steel or malleable cast iron. This type of anchor is increasingly being used to connect road-structure components in Victoriaís Big Build projects. The use of this bonded anchors in road- structures and the associated risks are required to understand well by designers, contractors and asset owners. Failure of this bonded anchors have the potential risk human lives and have considerable economic impacts Factors commonly contributing to the failure of anchors include poor workmanship, poor specification of products, not well understanding of performance limitations of anchors and suitability of bonded anchors for particular connections.

In Australia, Europe and the U.S., the design methodology for bonded anchors is based on the concrete capacity method which requires consideration of each possible failure mode of the base material and steel component. Correct design, specification and workmanship are essential to a successful and durable outcome. This paper discusses the testing results from pull-out test on bonded non-galvanised (black) and hot dipped galvanised (HDG) reinforcing bars and use in Victoriaís Big Build Projects. An experimental program was conducted by the Department of Transport Victoria, Major Road Projects Victoria and Swinburne University of Technology. Twenty tests were conducted with two epoxy adhesives and two types of reinforcing bars: (i) non-galvanised steel reinforcing bars and (ii) HDG reinforcing bars. The bond strengths for both reinforcing bar types were found to be higher than that published data in pre-qualification reports (ETA). The bond strengths of HDG reinforcing bars have far exceeded the threshold to meet the values in published prequalification reports for non-galvanised steel reinforcing bar. According to EAD 330087, the threshold value of bond strength is 11.6MPa to use the design strength of 2.7MPa for the concrete used in the experiment. Bond strengths from the experiment for both epoxy adhesives were more than 2-3 times the threshold value. This indicates that there is no evidence to justify any modification in the design bond data published for reinforcing bars based on European prequalification criteria.