- 16th February 2018
- Posted by: Joanne Woodhouse
- Category: Projects
Jordan bridge is a 34m long double intersection Pratt truss steel bridge built during the early 20th century which provides access to Blackburn Meadows biomass and pumping station. Due to the deteriorated state of the bridge, we were tasked with assessing the structure and designing strengthening works.
The bridge is in constant use providing access to the biomass and pumping station making planning of the strengthening works challenging. In addition, the existing top plan bracing connection between the trusses had advanced corrosion and the transverse beams had a low bearing capacity, presenting a serious risk of collapse if the structure was overloaded.
To minimise the extent of works above the river and to avoid any impact on the biomass and pumping station traffic flow, a strengthening system was developed to increase the capacity of the transverse beams while providing restraint to the top cords making up for the damaged top plan bracing, designed to be built in sub-assemblies.
An extensive analysis of the top chords was performed by numerical and analytical methods. The analysis of the top chords helped to optimise the amount of strengthening frames required and reduced H&S risks associated with site works.
Strengthening works were designed to be prefabricated in subassemblies which were easy to transport and install from underneath the bridge, reducing construction costs and installation time while avoiding disruption to the activities carried out at the biomass and pumping station.