The client had already designed and constructed high wooden towers from conventional tube scaffolding, ply and period cladding. They wanted to retrofit 40' long period rope bridges to these towers, that could take action, move naturally and be safe 16' off the ground. The existing wooden towers weren’t designed to take any lateral load. They were fully constructed with a 18” square hatch for access.
OMEY were asked by Vikings to design and build an engineering solution. We started by calculating the loads the rope bridges would exert at the top of the tower using catenary equations. We predicted the static loads associated with the dead load of rope and timber dressing, and the dynamic loads associated with 8 people walking.
Armed with the prediction of loading we designed a conventional suspension bridge system with stanchion and stays. Using CAD we sized the steelwork required in the stanchion to take the compressive load. Simple vector maths were used to predict the stresses on the stays.
The most difficult challenge was to get the steelwork into the towers with minimal intervention. We designed a kit of parts that could be manhandled through the small hatch and reassembled around the scaffolding. Remember that the stanchions have to move with the rope bride to transmit the load to the base via the stays, without touching the tower.
The whole setup was designed built and constructed by OMEY within two weeks. OMEY completed detailed OHSA risk assessments with the client. OMEY continues to support the client, as the bridges are used regularly throughout the subsequent seasons.