The Ashgrove Avenue Bridge is a reinforced concrete structure built around 1925. Its five-span beam-and-slab superstructure was continuous over the internal concrete wall piers and simply supported on phosphor-bronze plate bearings at each abutment. During the most recent Level 2 inspection, the bearings were found to be severely corroded. As a result, Brisbane City Council (BCC) engaged HDR to carry out a Level 3 inspection to confirm these findings and assess the bridge’s residual life, with the goal of identifying and optimising future repair strategies.

HDR’s Level 3 inspection revealed that the top and bottom cast iron bearing restraint plates were heavily corroded, creating a risk that the restrained phosphor-bronze bearing plates could dislodge and cause significant structural damage. The residual life of the bearing components on the western abutment was estimated at only three to five years.

HDR’s scope was subsequently expanded to include the design of a bearing replacement solution to extend the service life of this critical asset. The original bridge design did not accommodate jacking, and the situation was further complicated by abutments founded on slender driven timber piles, which prevented eccentric jacking from the front face of the abutment. The only practical and safe method identified was to use hydraulic flat jacks positioned along the centroid of the deck end diaphragm beam and abutment. However, the concrete end diaphragms were sparsely reinforced and contained large, irregular penetrations, necessitating the use of finite element analysis (FEA) to develop and verify the complex jacking and bearing replacement design.

This project showcased HDR’s ability to deliver comprehensive inspection, analysis, and innovative design solutions for a complex heritage structure. By overcoming significant jacking and structural challenges, HDR successfully developed a safe and practical bearing replacement strategy, delivering the long-term serviceability of this critical asset for Brisbane City Council.