Bridges

The use of bonded anchors has increased significantly since the last major update of DoT Standard Specification Section 680 (Bonded Anchors) in 2016, with the commencement of Victoriaís Big Build programme over the past few years. The Big Build is delivering 165 major road and rail projects, including major road upgrades, construction of tunnels, removal of a significant number of level crossings, delivery of the Suburban Rail Loop and Melbourne Airport Rail and regional passenger line upgrades. The Big Build delivery agencies (MTIA, SRLA) work closely with the Department of Transport (DoT) in planning, delivery, and construction of these major transport projects. Given the accelerated nature of construction of all these Big Build projects, designs are optimised to facilitate fast-track construction, and this includes the proposed use of bonded anchors instead of the more difficult, more time consuming and, in most cases, more expensive cast-in, positive structural connections of various concrete members. As such, bonded anchors are used to make structural connections to concrete surfaces of tunnels, bridges, and structural roadway components by facilitating the transfer of high applied loads.

To meet the challenges presented by these significant construction projects, including the required design life of 100 years, DoT Specification Section 680 was updated in early 2021 and 2022 to allow for a design life of 100 years for bonded anchors, enhance the training and competency requirements of installers, further improve the installation and workmanship requirements, streamline load testing, introduce trial installations, address fire resistance and elevated temperature effects, sealing of cracks, fatigue loading and protection of bonded anchors against moisture ingress and further improvements in other general requirements. The paper further highlights key activities which must be better controlled to minimise any adverse impacts on the adhesive bond strength and long-term structural and safety performance of bonded anchors.