“Hollow steel sections were selected for this project to optimise the steelwork arrangement. The 72m-long span roof trusses are curved on elevation, so the hollow sections used for the chords were selected as the best solution to resist significant axial forces, in addition to the secondary forces and moments induced by the geometry and bending process,” says Arup Associate Mike Wood.
“Our truss design carefully considered the chord and diagonal element member sizes to ensure an efficient arrangement of welded connections without the need for stiffeners.”
The truss top chords were fabricated from 400mm x 400mm SHS members, the bottom chords from 300mm x 300mm SHS members and the diagonal internal members from 250mm x 150mm RHS’s.
Hollow sections were also used for the building’s bracing members, to deal with large compression forces, which proved to be the most efficient use of material. These were fabricated from CHS members, ranging in size from 193.7-diameter up to 273mm-diameter sections.
Besides the structural and aesthetic benefits, the advantage of using closed hollow sections in a swimming pool hall is that the fixings from the roof and cladding are isolated from the corrosive swimming pool environment, and that there is less potential for any moisture to sit.
Billington Structures says, due to their size, each truss was fabricated in four pieces, which allowed them to be transported to site. Once the truss sections were delivered to site, the erectors used two laydown and assembly areas on either side of the building, where the steelwork was bolted together to form two halves of the entire roof truss.
Each half was lifted into position with a tandem lift using two 250t-capacity crawler cranes that brought the two pairs together in mid-air and this is where the final connections were made. Once this final connection was completed, the project team manoeuvred the entire truss to its final position, and made the bolted connections to the perimeter columns, with the aid of a 90t-capacity mobile crane positioned with the footprint of the structure.
“Hollow steel sections were selected for a variety of reasons, structural, technical, and aesthetic, dependent on their location,” says Chris Kent of project architect Roberts Limbrick.
“As well as using SHS sections for the trusses, CHS columns were selected over universal column sections in the front of house areas, such as the café and foyer.”
The CHS columns were primarily 200mm-diameter and 250mm-diameter members, however, larger 323mm-diameter and 273mm-diameter CHS sections were used in and around the Centre’s entrance area.
Recognising the complexity of design and the associated challenges that were overcome, the Sandwell Aquatics Centre was the winner of the Tekla Awards’ Sports & Recreation category in 2021.