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Structural engineer's account

Watson Steel and Deakin Callard & Partners respectively

The new Reebok Stadium was opened at the start of the 1997 football season, coinciding with Bolton Wanderers' promotion to the premier league. It is a particularly unusual structure with a unique form of roof construction, dictated by the complex roof geometry and the requirement for unobstructed views from the stands and the corners. The terrace support structure, while more conventional in comparison with the roof, has large spans to accommodate the high-specification facilities required.

Watson Steel was taken on board at an early stage to carry out the detailed design of the roof and terrace steelwork. A contract was subsequently awarded to Watson for the supply and erection of the steelwork. Deakin Callard & Partners was appointed to design the groundworks, foundations and concrete floors within the building. Throughout the design period, a close liaison was maintained with the football club and lobb Sports Architecture.

The geometry of the stadium is based on an elliptical footprint. This in turn leads to a curved roof profile, reducing to the corners as the height of the terracing reduces.

The structural solution for the roof works with the geometry by using inclined plane trusses, springing from supports outside the corners. The orientation of the truss, when transposed on to the curved roof surface, ensures it is positioned towards the front edge for most of its length, thus optimising the roof loading between the truss and the rear columns.

The stability of the truss relies on pre-tensioned tie bars at main rafter positions. These perform a dual function in that they also support the front rafter cantilevers.

The trusses span between corner pylons which transfer the large axial trusts down to the ground. Foundations to each of these corner pylons comprise three groups of axially and laterally loaded piles socketed into Coal Measures Strata. The largest of these groups incorporates 42 piles, with a pile cap constructed from 400m3 of concrete and 17 tonnes of reinforcing steel. Each support is required to sustain lateral thrusts of up to 1100 tonnes and downward and uplift forces of 850 tonnes and 550 tonnes respectively in certain loading conditions.

The terrace structure is required to span large distances, dictating the need for tapered-plate girder rakers. On the East Stand, the requirement to span 30m while still supporting the roof and terracing led to an innovative truss solution, using the rakers and floor beams with a sloping external tubular member. Terrace foundations are similar in type to those supporting the corner pylons.

The ground-floor slab is non-suspended to the south of the stadium and is supported on piles to the north, reflecting the change in ground conditions across the footprint of the building.

Cost comment

ERIC O'NEIL

O'Neil and Partners

The football club directors wanted the Reebok Stadium to be an architectural statement conceptually different from all other stadia, the best of its size in Europe, capable of being used seven days a week for non-football activities, of housing a minimum of 25,000 spectators, not to exceed £25 million in cost and to be ready for the start of the 1997/98 season.

The contract basis was jct81 design and build with a guaranteed maximum price, with the whole of the design team except the quantity surveyor being novated.

Tenderers were sought from a restricted list of contractors on a two- stage basis: they were initially requested to supply percentage figures for preliminaries, overheads and profit prior to submission and presentation of their bid which had to demonstrate an understanding of the project, state methodology of construction, indicate programme measures and finally set out the cost.

It was at this stage that the contractor was selected and the final stadium configuration and cost were negotiated. The basis of procurement was set up for competitive subcontractor packages, with all members of the team contributing to the development of construction. The whole process was hugely helped by the club directors giving the go-ahead to procure and fabricate the steelwork before contracts had been exchanged.

The costs of the stadium do not include the pitch, which was laid approximately two years before use, and the car parking and infrastructure, which were included in the costs of the overall development of the retail site.

There is little benefit to be gained in expressing costs elementally, as these would be distorted by the large number of components that are particular to football stadia. The accepted method is by cost/seat, and the Reebok Stadium cost £915.00 per seat, which may be adjudged high if you fail to view the project as taking the design onward to the next generation.

Cost elements £

Foundations 714,564

Piling 333,643

Methane venting system 32,928

Structural steelwork and 7,265,528intumescent painting

In-situ concrete slabs 960,031

Metal floor decking 279,087

Precast concrete terracing 945,577

and vomitories

Brickwork and blockwork 1,479.854

Wall and roof cladding 1,273.724

Curtain walling 268,198

Secondary steelwork 378,444

Staircases and balustrades 633,725

Barriers, handrails and fencing 119,912

Turnstiles 127,936

Woodwork 529,438

Hospitality box glazing 295,056

Exit doors and gates 66,180

Kiosk shutters 67,798

Floor, wall and ceiling finishings 614,547

including decoration

Stadium seating 366,130

Dugouts 7,559

Sanitaryware 189,521

Mechanical installations 1,815,592

Electrical installations 2,350,000

Lift installation 108,879

Television gantry 25,005

Signage 39,192

Builder's work for services 62,580

installations

Drainage 290,385

Sewer diversion 169,416

External works 349,999

Contract bond 76,348

Building regulation fees 82,000

Preliminaries 3,130,432

Total £25,449,208

CREDITS

CLIENT Bolton Wanderers Football Club

ARCHITECT lobb Sports Architecture: Rod Sheard, Derek Wilson, Dale Jennins, Angus Denvir, Ashley Monday, Madeline Larkin, Bill Augustyn

QUANTITY SURVEYOR

O'Neil & Partners

STRUCTURAL ENGINEERS

Watson Steel; Deakin Callard & Partners

SERVICES ENGINEER

W E Hannans

FIRE CONSULTANT

Warrington Fire

MAIN CONTRACTOR

Birse Construction

CONTRACT TYPE

Design and Build

START DATE

June 1996

COMPLETION DATE

1 September 1997

TOTAL COST

£25 million

SUBCONTRACTORS AND SUPPLIERS

electrical Piggot & Whitfield, mechanical Ellsmere Engineering, additional structural steel Shawton Engineering, architectural steelwork pi Engineering, secondary steel Copper Rigg, cladding/roofing Hathaway, curtain walling Norking Aluminium, additional glazing S G Aluminium, louvres White Partridge, internal design Sucha Design, office heating A1 Plumbing, industrial doors Ascot, finishings Ashton Ceramics, precast stairs Barcon, precast terracing Bison, scaffolding Bolton Scaffolding, turnstiles Broughton Controls, mastic pointing Bulman Sealants, stair-edge protection Cape Scaffolding, piling Cementation Piling, compound fencing Contract Services, suspended ceilings Cowill, cubicles Delta Laminates, temporary electrics C W Dowd, sealants Fastglobe Mastics, underslab drainage M A Flynn, syphonic flat roof Fullflow, concrete foundations and slabs Gormley Construction, sewer diversion D Gallagher, joinery Garriff Joinery, earthworks A K Hale, doors and gates Henderson Bostwick, plastering T Mansell, sanitaryware D S Matthews, brick/blockwork Marshall Errock, seating Metalliform, intumescent painting Modern Fireproofing, metal decking msw, stud partitions Newcap, lifts Otis, syphonic main roof psg, scissors stairs Shawton Engineering, brickwork support T W Fabrications

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