Bridges

The 313 m precast segmental box girder Victoria Bridge is a key Brisbane River crossing opened in 1969 and remains a central link for public transport, pedestrians and cyclists within the city. As part of the Brisbane Metro Project, the bridge was reconfigured to suit the new electric Metro fleet while also providing a dedicated cycle corridor to supplement pedestrian walkways.

Due to the change of use, a detailed assessment of the structure was undertaken and identified theoretical overutilisations in several areas. Investigations showed that strengthening of the bridge to achieve full compliance to current Australian Standards Bridge Design suite (AS5100) was not practical, with various areas of the bridge including halving joints limiting its capacity. Additionally, as any strengthening works would require significant invasive drilling and coring into the heavily prestressed structure, overly conservative strengthening schemes were not seen as viable options.

To address this, a bridge-specific design criteria was developed with close collaboration between the engineer, Client (and asset delegate) and Client’s Technical Advisor to agree a rational set of parameters on which to base the strengthening works. This process involved the development of numerous ‘Special Studies’ to determine suitable parameters outside the typical scope of the code as well as the agreement of various parameters with the 'Relevant Authority' (BCC) in accordance with AS5100 provisions. Where parameters were deemed to be departures from the code, robust processes were implemented to ensure technical reviews and subsequent acceptance by the Client were carried out in a transparent manner.

This paper presents the processes and workflows developed to facilitate the documentation and agreement of the departures, discusses key departures and their significance on the final strengthening design and comments on the applicability of such an approach to future projects and the sustainable asset management field.