WORKING with DeltaBeams has been a revelation for Byrne Brothers, the frame contractor on Drake Circus.
As an in-situ concrete specialist, Byrne Brothers had no previous experience with this system. Construction director Steve Lilley is now an enthusiastic advocate of DeltaBeam.
'It's a brilliant concept. It's quick, efficient and removes a lot of the labour requirement, ' he says.
Mr Lilley is particularly impressed by the clear wide spans achievable, and the absence of any downstand beams.
'Normally you'd have to cast holes in the downstand beams for the services and this often creates problems. The holes are in the wrong place, or they're the wrong size, or they're not properly aligned? This does away with all that, ' says Mr Lilley.
Byrne's project manager on site, Jim St John, is impressed with the speed of construction. 'When everything goes well, it's incredibly quick. You can do one big bay in a day, ' he says. Mr St John has two men fixing the DeltaBeams and another team of about six dropping the hollow-core planks into place. An area of floor incorporating 25 DeltaBeams can be completed in two or three days by this team.
But there is a caveat. 'It's all got to fit perfectly, ' says Mr St John. Whereas on an in-situ frame slight errors can be accommodated by judicious bending of the rebar and repositioning of formwork, the bolted connections between the DeltaBeams and the steel corbels cast into the in-situ stair cores and perimeter walls leave little room for error.
'A small error can cause massive delays, ' says Mr St John. He and his team have followed a steep learning curve, engineering solutions as they go. It is a constant challenge since all of the DeltaBeams on Drake Circus are bespoke.
Assembling the frame has more in common with structural steel than in-situ concrete, but Mr St John doubts a steelwork contractor would find it any easier than he has.
'The columns are designed by one company and the DeltaBeams by another. It's not surprising there have been some interface issues. A steelwork contractor's used to designing it all himself. Plus there's the concreting after the planks are installed. So no, I don't think they would find it any easier than us.'