Lockyer Creek Bridge - Steel Girder Strengthening and Re-painting Works

Abstract

Lockyer Bridge was constructed in 1966 and is a 7-span steel girder bridge,112m long, located on (314) Gatton-Helidon Road Ch 9.59 to 9.703km. Superstructure consists of 5 steel girders per span with a reinforced concrete deck and the substructure consists of a reinforced concrete headstock support on two reinforced columns, pile cap and driven concrete piles. The bridge was identified as a priority bridge based on the assessment undertaken as part of the Road Train and B-double Network Bridge Structural Assessment Project. Investigations by TMR E&T unit into the capacity of the bridge had indicated that the structure was operating at slightly less margins than the margins established by AS 5100. As such, the structure was operating under an interim structure management plan until strengthening occurred. As per the interim structure management plan, the structure was not allowed to increase its permissible as of right vehicle load (30m PBS Level 2B vehicle at HML) load or dead load (such as new wearing surface). The strengthening design (in accordance with AS 5100) had been completed by TMR E&T unit in 2016-2017 to address those issues related to strength limit state. Strengthening design included strengthening of concrete headstocks on all piers as well as the steel girders for the continuous spans at spans 5, 6 and 7. In addition, a paint assessment found the existing paint was not protecting the underlying steel on the girders. Recommended treatment was to apply zinc-rich prime, intermediate coat, and a polysiloxane topcoat. High-level scope of the project was; • Undertake bridge strengthening works • Re-paint girders • Other bridge rehabilitation works as per Structure Management Plan RoadTek (DSW) was tasked to carry out this rehabilitation work in collaboration with PD&O (Darling Downs), TMR E&T and RoadTek Structures unit in 2020.