Wicklow County Council recently commissioned Roughan & O'Donovan to conduct a structural assessment of Whitebridge, a 33m long three-span prestressed concrete bridge on the Avoca River in Co. Wicklow.
This follows a special investigation, undertaken by Roughan & O'Donovan, into the cause of corrosion discovered in the bridge's prestressed beams in 2015.
The structural assessment required a physical structural investigation to determine the capacity of the bridge’s beams, and this was carried by specialist contractor Henderson Thomas Associates, under Roughan & O'Donovan’s supervision.
The investigation involved drilling cores into the deck and breaking out sections of concrete at the ends of the beams. Great care was needed so as not to remove any part of the deck supported by the bridge bearings.
Roughan & O'Donovan was able to determine the strand arrangement from the steel protruding from the beams, and the distinction between concrete that had been precast and concrete that was poured after the beams were installed from the different concrete colours and textures.
The capacity of the beams was calculated once the investigation was complete and all necessary data had been gathered.
The load effects on the bridge were assessed using MIDAS finite element software.
The assessment confirmed that the bridge was capable of carrying the required traffic loading, based on the heaviest design vehicle being 150 tonnes.
