Client:

Central Scaffolding & Queensland Rail

Project Overview:

FortisEM recently completed detailed engineering of an access scaffold system for the Merivale Bridge located in Brisbane. The project is quite unique and showcases the structural capacity of Layher for high load situations. The scaffold itself is over 21m high at it’s highest point, has a 14m clear span along it’s center and during an Ultimate Limit State wind event (i.e. cyclone) it is supported on just two points for each bay, one each side of the bridge, due to the way the structure deflects under lateral loads.

The design wind speed was crucial to the design of the scaffold given it’s shear height and limited support. A climatic wind study was undertaken which allowed the engineering team to use an optimized design wind speed that took into account real word climatic data for the site. The numerical modelling for this wind climate study was based on 62 years of weather records for the Brisbane region. Based on the climatic wind study the design speed for the site was calculated as 49m/s (176.4km/hr).

Due to the complex cable stayed arch structure of the bridge, the bridge was 3d Laser Scanned prior to commencement of the project. This allowed the 48.3 Scaffolding Consultants team to accurately model and locate all elements of the existing structure and the scaffold structure. This was crucial to ensure the ladder beams spanning over the train tracks and HV cables could be installed during the small shut down window that was available and to ensure no clashes.

The design also show cased the structural capacity of Layher. At the Ultimate Limit State design the base standards and bracing system are at 99% utilization. With axial forces well above 60kN, getting the design right whilst optimizing the amount of scaffold was crucial. Whilst there are many product on the market, the detail design information available from Layher made engineering of the scaffold system much easier than it might have been.