Bryson Crane has utilised a Terex all-terrain crane, equipped with two Modulift spreader beams below-the-hook, in order to lift a 40.8-tonne prefabricated building at a communications tower in Edgewater, Florida.
In total, 17 buildings will be moved into position. The Modulift MOD 50 spreaders, which have a capacity of up to 50 tonnes at an 8 m outreach, were used with slings, shackles, and rolling blocks; the 130-tonne capacity Terex Explorer 5500 employed its 60 m-long main boom to lift and move the unit a distance of 9.14 m.
Scott Woodward, facilities manager at Modulift distributor I&I Sling, said that Bryson's biggest challenge was presented by an offset centre of gravity, caused by backup batteries that are housed at the end of each building.
Ray Rutt, operations manager at Bryson, added: "By adding length to the rigging, we were able to ensure that each bottom sling that was connected to each pair of lifting points was equally tensioned by the wire rope moving over the roller. This particular rig configuration will commonly warrant the use of rolling blocks."
Bryson opted to use a compact rig to reduce the height and keep the spreader bars close to the load. "This rig is more commonly used when there are four bottom lifting points [not eight as in this case] and the rig height is crucial. As there were a greater number of lifting points, the rolling blocks were a requirement."
Rutt added that Bryson selected the spreader beam configuration versus a lifting frame because it already owned one MOD 50 and it made sense to acquire an additional unit. The 17 lifts are scheduled to take place over the coming weeks.