IABSE SYMPOSIUM MELBOURNE 2002 i

Three New World Class Sporting Facilities in Melbourne

Mark SHELDON Senior Associate Connell Mott MacDonald Melbourne, Australia

Peter CHANCELLOR Associate Connell Mott MacDonald Melbourne, Australia

Brian DEAN Principal Connell Mott MacDonald Melbourne, Australia

Mark Sheldon received his Bachelor of Engineering in 1982, and has been a key team member of significant sporting projects including the MCG, Colonial Stadium, Vodafone Arena, the Melbourne Sports and Aquatic Centre and Wembley Stadium.

Peter Chancellor has over 20 years experience in Structural Engineering and has been a key team member for design of a number of major projects including; Melbourne Central, Colonial Stadium, VRC Flemington Grandstand and Eureka Tower.

Brian Dean is a Principal of Connell Mott MacDonald and leads the Buildings Group. He received his 1st Class Honours degree from Edinburgh University in 1970 and has extensive experience in Australia, Nigeria and United Kingdom.

Summary Three new World Class sporting facilities have been designed by Connell Mott MacDonald and opened since the year 2000. These consist of the 52,000 seat Colonial Stadium, primarily for the main football codes; the Vodafone Arena, which is a true multipurpose venue for over 10,000 spectators; and the Victoria Racing Club’s new Members Grandstand at Flemington, home of the Melbourne Cup. Each of these facilities feature a number of unusual and innovative solutions ranging from a moving roof 168 metres x 54 metres which can close in 8 minutes, spectator seating that can be winched up to the ceiling to reveal an international standard velodrome, and frameless glass enclosing cantilevering seating tiers.

This paper summarises some of the interesting engineering solutions adopted for these projects.

Keywords: Colonial Stadium, VRC, Vodafone Arena, Grandstands, Retractable roof, Longspan, CFD modelling

Connell Mott MacDonald have provided all engineering services to three world class sporting facilities which have opened in Melbourne in the new millennium.

The Colonial Stadium is a 52,000 seating stadium suited to Australian Rules Football and cricket, with the facility for 12,500 seats in the lower tier to be driven forward for a more intimate concert, rugby or soccer event. Crowning the stadium is a fully closable roof consisting of two panels, each 168metres long and 52metres wide.

The Vodafone Arena is a true multipurpose venue. Based on an Olympic-standard velodrome track, the facility includes seating tiers that can be lowered down from the roof over the track to create a basketball/ tennis/ concert venue for 10,000 people. This facility also features a fully closable roof, and is used as Court 1 for the Australian Open Tennis Event.

The VRC Members Grandstand includes four sloping tiers of seating with a frameless glazed facade to the front of the building. This was constructed over the top of an existing building. Fire Engineering techniques were used to justify not protecting the majority of the steel beams and columns resulting in significant cost savings.

Colonial Stadium is a landmark structure unlike any other sports stadium in the world. Built at a cost of $A460 million this multi-purpose venue can accommodate 52,000 spectators in comfort at an AFL or cricket match. It features a versatile seating system, whereby 12,500 seats can be rolled forward on 115 metre long trussed frames. However, it is the moving roof, which crowns this magnificent engineering achievement. Covering the 160 metre by 100 metre opening are two panels, each weighting approximately 1200 tonnes, which can fully enclose the pitch in approximately 8 minutes. The design of these panels by Connell Mott MacDonald incorporated shiploader technology to develop the bogie mechanisms and control systems.

The design needed to pay particular attention to many issues that can simply be dismissed on “normal-scale” projects. The implications of thermal movements in the order of 100mm and deflections of over 0.5 metres had to be evaluated.

2.1 Client Brief

The major requirements of the Design Brief included: • 52,000 seat stadium • retractable roof offering ‘dripline’ coverage to 50,000 seats in the open position,

and fully closable in under 20 minutes (8 minutes achieved), retractable seating to bring lowest tier of seating as close as practical to soccer/rugby pitch on all sides

• 2500 carspaces on site, including under the suspended pitch • 6500 seats in dining facilities • 66 corporate boxes • Nightclubs, sports bars, television studio, media facilities etc

1. Introduction

2. Colonial Stadium, Docklands

Fig 1: Colonial Stadium

2.2 Features and Solutions

2.2.1 The Roof

The feature that really strikes all first-time visitors to the stadium is the enormity of the roof. The concept for the fixed roof structure is simple, but elegant. Four major steel trusses form the main supports for the rectangular opening in the fixed roof, including bowstring trusses on the east and west sides which are 12 metres deep and span 150 metres. These trusses are underslung, to enable the moving roof panels to pass over in an east-west direction. Supporting the moving roof rails on the north and south ends are arched trusses rising 14 metres above the roof, and spanning 120 metres. Stability of the top chord member is a major consideration. Buckling is restrained by the fixed roof secondary trusses T1 which span back to bearings at the rear of the stand. The fixed roof secondary steel trusses are of conventional form spanning up to 40m, with a 15m cantilever. The retractable roof consists of two panels, each 168 metres long and 52 metres wide, which run on rails and park over the top of the fixed east and west roof structures. Each of these panels is supported by two three-dimensional steel trusses, which are approximately 12 metres high with a clear span of 165 metres. Each of these roof panels weigh approximately 1200 tonne, and during closing travels the 50 metres in approximately 8 minutes.

Fig 2: Typical Cross Section – Colonial Stadium

2.2.2 Cantilevered Seating Tiers

The Colonial Stadium features two upper tiers of seating, both cantilevering approximately 6.5 metres. These support precast pre-tensioned concrete seating plats of varying heights, set out in parabolic curves to ensure optimum viewing sightlines for the patrons.

Although it was demanded that the stadium would be a world-class facility, economy of design was also a major consideration. Whilst the criteria for the design for strength and deflection is well documented and codified, the dynamic (vibration) performance is not covered by any Australian Standard.

Realising that adoption of a conservative criterion could add considerably to the cost of the project, papers and references were scoured for an alternative credible basis for the design. A rational approach, based on measured results, was therefore devised by Connell Mott MacDonald and used as a basis of the design. This design featured relatively light but deep structural steel cantilever girders (up to 1900mm deep), to a profile developed in conjunction with the architect to create visual appeal and structural functionality.

2.2.3 Construction Issues

In order to reduce the effect of the erection of the retractable roof on the critical path, it was decided to assemble the retractable roof at ground level outside the stadium, jack it to height from temporary jacking towers, and then roll it onto the stadium structure using an extension to the permanent runway truss. This also allowed for the majority of the steel erection, plus following trades (cladding, flashing, ceiling linings, electrical works) to be done at ground level as distinct from 45m in the air. The fixed roof was erected from within the stadium using a combination of large cranes.

In order to satisfy the residual stress limitations and deflection criteria, a maximum span between temporary towers of 37.5m was determined, and each tower preset to height to allow for the truss pre-camber. As the pre-camber was significant, the de-propping was performed incrementally to a sequence agreed with Connell Mott MacDonald, over a period of approximately six hours.

Fig 3: Raising one of the moving roof portions – Colonial Stadium

The lack of space on the site for the panel assembly, and the practical limitations on size, precluded the assembly and jacking of a complete roof panel in one piece.

The concept adopted was to split each panel longitudinally into two half-plates, each still 168m long, but 26m wide and formed by one of the three-dimensional trusses and half the underslung roof structure.

Initial calculations showed that the abutting rafter ends between each half plate would be out of alignment by approximately 900mm vertically. This problem was overcome by omitting various areas of roof cladding and purlins on each half plate, so that the deflections of each half plate were similar.

2.2.4 Pitch Structure

The site is underlain by deep compressible silts which exhibit ongoing settlements of varying amounts.

Differential settlement up to 300 mm in 25 years is expected. This differential settlement would result in long term maintenance difficulties and a suspended pitch support structure was adopted. This structure comprised a post tensioned concrete floor supported on driven precast piles.

The area under the pitch is used for car parking and effectively reduced the car parking that would have otherwise been required elsewhere on the site.

2.2.5 Erection

To enable the cranes, (up to 600 tonne mobile cranes) etc, to exit the stadium after the roof elements had been lifted, a construction ‘opening’ through the lower levels in one bay on the west side has been provided. However, as the roof structure could not be erected until after the bowl steelwork and seating plats were in position, the upper levels still had to be constructed, necessitating transfer beams spanning up to 15 metres at level 2. These are post-tensioned beams up to 1400mm deep and 1800mm wide, which were stage stressed as more and more load was applied to the midspan column over.

After completion of the roof, the cranes exited the central pitch area, allowing columns to be installed at midspan under the temporary transfer in the final configuration, using jacking to pre-load these columns to attract their design loads.

2.3 CFD Modelling

Connell Mott MacDonald carried out a number of investigations into the natural ventilation of the Colonial Stadium bowl including a wide range of Computational Fluid Dynamics (CFD) studies. The purpose of the CFD studies was to optimise the design from a capital cost perspective and to address architectural concerns regarding possible drafts and wind driven rain as well as noise breakout issues.

Optimisation studies included the assessment of different roof vent configurations and spacings as well as several variations to the facade opening restrictions, with the final scheme being further tested against a range of ambient and occupancy conditions as part of a sensitivity study.

Furthermore, an extensive range of engineering analysis and supplementary CFD modelling was performed to confirm that conditions in the bowl in the event of a major pitch fire during a concert or similar, with the stadium roof closed would satisfy mandatory life safety criteria.

Fig 4: CFD Modelling of a Fire Event – Colonial Stadium

The Vodafone Arena is a world class facility which includes innovative engineering and bold structural concepts. This multi-purpose arena was built at a cost of $A60 million. The flexible arena can accommodate up to 10,000 spectators in tennis or basketball mode and up to 10,800 in entertainment mode. The seating system can be manoeuvred to reveal a hidden 250 metre world class velodrome track which can be viewed by up to 4,500 spectators.

The concept for this multi-purpose venue was developed by Peddle Thorp Architects in close consultation with Connell Mott MacDonald.

The key challenge to achieve a sophisticated multi purpose venue was to combine the elements of a tennis centre, velodrome track, raiseable seating, retractable roof various lighting configurations, and a public address system under one roof has been achieved with great success. This multi-purpose arena is a land mark for stadiums throughout the world.

The key to the stadium’s flexibility is its seating systems of which there are three forms, raiseable, removable and retractable.

3. Vodafone Arena

The 70 tonne north and south “raiseable seating” panel structures are hinged and may be hoisted upwards by detachable steel cables fixed to a roof mounted winching system. The seating panels are then raised and locked-off to the underside of the fixed roof trusses. The raising of these seats takes only 12 minutes to expose the full field of the arena and the steep ends of the velodrome track.

The “removable seating” panels span over the east and west sections of the velodrome track and provide excellent site lines and close viewing for all events held in the centre of the arena. These are winched up to the underside of the roof for storage when the velodrome or an end-stage format is in use.

The “retractable seating” systems are within the north, south, east and west sections of the centre arena and provide flexibility, maximum seating capacities and the closest viewing for a centre-stage format.

The stadium features a moveable roof, which separates into two sections and operates on a north south track. Each roof section is 32m x 70m and takes a maximum of ten minutes to fully open or close.

120 tonnes of rigged sound, lighting and stage prop equipment may be hung from the underside of the two moveable roof panels and the underside of the raiseable seating structure.

Fig 5: Vodafone Arena

3.1 Client Brief • To provide a 10,000 seat stadium for the Australian Tennis Open • To provide a 10,000 seat purpose built basketball venue. • To provide a 4,500 seat internationally accredited velodrome. • To provide a flexible entertainment venue to house up to 10,000 • To provide corporate facilities to include superboxes, lounges, club areas,

restaurants and media facilities to promote events and generate income.

Fig 6: Cross Section Through Vodafone Arena

3.2 Features and Solutions

3.2.1 Retractable Roof

Two retractable roof panels 32 m x 70 m , each are driven by multiple synchronised electric motors with Variable Voltage Variable Frequency drives located on four bogies with the fifth a lateral restraint bogie. The panels travel at variable speed of 0.1 m/s in the north south direction, opening and closing within 8 minutes subject to wind conditions or in small increments to expose the skylight only for natural lighting or adjust to suit playing surface sun conditions.

These large roof panels were constructed on the ground alongside the stadium, then “walked” and lifted into position using a 600 tonne crawler crane.

Fig 7: Erecting One Roof Panel, Vodafone Arena

3.2.2 Fixed Roof

The fixed roof is supported by two main 7 metre depth 81metre span rectangular shaped trusses and two 5.5 metre depth secondary trusses. These trusses form the roof opening and were dimensioned to fit between sight lines at their underside and allowable shadow lines cast from the top edge to the tennis arena below. The trusses also act as a support and carriage for the building services and service access around the arena.

The top chords of the main trusses have been utilised to form the runway beams for the moveable roof bogies.

3.2.3 Field Access Through the Velodrome Track

The velodrome track is a timber structure which can float on its supports to allow track movements due to changes in temperature and moisture within the timber.

The centre arena can be accessed by pantechnicons and other large vehicles through a door in the 42 degree sloped ends of velodrome track. This innovative feature is believed to be a world first for an internationally accredited track.

The Victoria Racing Club's new Grandstand has been designed to offer a range of facilities unmatched at any Racecourse in the world. The facilities at this new seven level grandstand include a high tech betting Forum with a state of art audio visual installation, and two viewing levels. Supporting the public spaces are fully equipped kitchens, serveries and bars. The 7000 spectator seats are situated over five levels and offer unimpeded view of the track from behind glass.

Computer modelling enabled eaves to be employed to provide shade to the north and south glazing, thereby reducing heat load. Connell Mott MacDonald also employed fire-engineering principles to allow considerate use of unprotected steel and resulting cost savings.

This successful project was constructed to a tight budget and within tight time constraints whilst maintaining full operation of the facility during the process. Staging operation and solutions were developed to achieve this and were accounted for in the design solutions.

Connell Mott MacDonald provided full engineering services for this project. This was a major benefit as services required close coordination with structure to develop the optimal solution for the building as a whole. This was effectively carried out with designs of different disciplines working together.

4.1 Client Brief

The brief was to provide a new grandstand facility that is diverse, flexible and adaptable, that visually unifies and integrates the suite of built facilities at Flemington, and provides members with a range of elegant and stylish facilities.

4.2 Features and Solutions

The structural design of the New Members Grandstand at the Victoria Racing Club, Flemington required innovative engineering and development of appropriate design solutions to enable construction of this complex project, including:

4. Members Grandstand - Victoria Racing Club, Flemington

4.2.1 Strengthening of Existing Building

An existing 2 and 3 level concrete structure build in the 1970 originally occupied the site. This existing building was extended to a 7 level facility to create the New Grandstand.

To carry the additional loading substantial strengthening works were required. This included:- • enlargement and strengthening of existing foundation. • strengthening of existing columns. • Upgrading of the existing stability elements (cores) for additional lateral loads

exerted by the new structure. This was achieved economically with exposed steel strapping reinforcement located within the stair shafts.

• Refined engineering analysis was carried out on aspects of the lateral stability analysis to minimise additional strengthening.

Fig 8: Section Through VRC Members Grandstand

4.2.2 Selection of New Structure

A steel framed structure was adopted after evaluation of criteria including:- • It is a lightweight structure which minimised strengthening to the existing

structure under. • Good for long span column free areas as required architecturally for large public

areas. (Grid spacings up to 18m and 9m were used. • Good for transfer structures, 1800mm deep transfer beams were required. • Allowed for rapid construction and clear access below. • Large cantilevers were required to support the trackside tiered seating. Inclined

columns were used to minimise the cantilever lengths.

In one area a new foundation was required above an existing sewer main and amongst major sections of existing structure. Tunnelling techniques were used to install an in ground bridging beam to distribute loads away from the sewer.

Dynamics A refined 3 dimensional dynamics analysis of the structural system was undertaken. For the long span primary beams and trackside cantilever the dynamic aspects governed the design.

The dynamic analysis was also benchmarked against actual measured performance and other designs by Connell Mot MacDonald.

4.2.3 Glazing

To add to the amenity of the grandstand, the trackside seating is fully enclosed behind a unique glazed facade. The vertical glass had to span up to 4m as well as vertically support the sloping glass roof, requiring 25mm thick glass (32mm in places beside openings) which was laminated and toughened. This solution had to take into account the movements of the cantilevers along with thermal and wind deflections.

The glazing system was also required to accommodate movements at up to 50mm from the supporting structure.

Fig 9: VRC Members Grandstand in use

5.1 Colonial Stadium, Docklands

Role of Firm: Engineering services including; Structural, Civil, Mechanical, Electrical, Hydraulics, Fire Protection, Bogie Traction System, Vertical Transportation, Communications and associated building services engineering. Client: (a) during construction - Baulderstone Hornibrook

(b) present - Melbourne Stadiums Limited

5. Project Details

Consultant Team: Architect - Daryl Jackson Bligh Lobb

Sports Architecture JV Civil & Building Services Engineer - Connell Mott MacDonald Structural Engineer - Connell Mott MacDonald,

with Modus (UK) as subconsultant

Quantity Surveyor - WT Partnership

5.2 Vodafone Arena

Role of firm: Engineering services including; Structural, Civil, Electrical, Hydraulics, Communications, Vertical Transportation, Fire Engineering, Mechanical Engineering, bogie traction systems and winch systems.

Client: Melbourne Olympic Park Trust Consultants Team: Architect - Peddle Thorp Melbourne Structural, Civil and Building Services Engineer - Connell Mott MacDonald Quantity Surveyor - WT Partnership Project Manager - John Wertheimer and Associates Velodrome Track Designer - Ron Webb

5.3 Members Grandstand - Victoria Racing Club, Flemington

Role of Firm: Engineering services including; Structural, Civil, Electrical, Mechanical, Hydraulics, Communications, Vertical Transportation, and Fire Engineering

Client: Victoria Racing Club Consultant Team: Principal Architects - The Buchan Group and K H

Edelstein Pty Ltd in Association Cost Consultant - WT Partnership Building Surveyor - The Gardner Group Builder - Probuild Constructions Pty Ltd