Business School by Karen Phelps
When Fletcher Construction project manager Richard Coupe first visited the University of Auckland Business School site on Auckland’s Grafton Street in 2004 he was impressed: “It was a huge hole.”
In fact the excavation completed by Vuksich and Borich was the second largest ever undertaken in Auckland, second only to the Sky City development (which Vuksich and Borich also completed).
When project engineer Matthew Vuksich first went to the site there were several existing houses, a car park and dense bush. Because a couple of the houses were over 100 years old they had to be dismantled with care to preserve original materials, which were destined to be reused in other projects. Vuksich and Borich removed approximately 135,000 cubic metres of soil in total from the site.
Part of Grafton Gully was also located on site, which Vuksich says posed access problems. The gully had to be in-filled with 8,000 cubic metres of clay in order for vehicles – three excavators and ten truck and trailer units - to be able to drive into the area.
“This access issue was the most critical part of the project and saved us a lot of double handling. From there we could really push the earthworks,” says Vuksich.
Because the site is situated on a sloping slip plane substantial ground retention work was required. One hundred 900-millimetre diametre piles were installed at two metre intervals around the perimetre of the site, some extending up to 25 metres into the ground.
“Two hundred and fifty anchors were used through the piles and were then tensioned to hold the wall back. Then 1300 metres of Atlantis strip drain were installed in the clay face to drain the wall. After this 1500 square metres of reinforced fibre shotcrete was sprayed over the clay face in between the piles to form the retention wall,” explains Vuksich. “Getting the duct locations for the anchors correct was tricky. We achieved this with a lot of lining up and surveying equipment.”
When the project was well under way five months into the contract things changed. The original brief was for a 90,000 cubic metre dig and this was extended to 135,000 cubic metres as plans for the Business School grew. The retention wall plan was extended including installing an additional 29 piles.
Inclined bored drains 50mm in diametre and receding into the clay face 20 metres were installed through the retention wall. Then 850 metres of subsoil drains 100 millimetre in diametre were interlinked from level four to level five of the car park, which included 36 manholes and 16 x 600 millimetre diametre chambers. These drains run around the perimetre of the building and through the centre. In total the earthwork took Vuksich and Borich a year to complete.
Construction work began in October 2004 and involved installing 130 concrete piles, each between 600-1200cm in diametre depending on the loading required. Because the structure is built on top of a substrate layer of sandstone Fletcher Construction project manager Richard Coupe says this made laying the concrete slab on grade (between 200-250 cm thick depending on the area) easier as it provided good stability. Then, says Coupe “we just went up” with the structural steel starting erection in March 05.
With a large 9000 square metre footprint, the Auckland Business School will be a significant landmark in Auckland City. The building contains nearly 3000 tonnes of primary steel and 4000 precast concrete double T’s and flat slabs. According to Coupe there are 74,000 square metres of concrete floor slab in the superstructure comprising of nearly 9000m3 of concrete. Over 3000 tonnes of reinforcing steel will be placed into the floor slabs and insitu walls.
With the original brief changing, the floor area increased by about a third as additional carparking plus 2 x 600 seat lecture theatres were added to the project, Fletchers commenced on site just as the first issue for construction deliverables were issued. The fast tracked nature of the project required Fletcher Construction to work very closely with the architects FJMT & Archimedia and Beca Structural and set priorities on the documentation requirements.
“There wasn’t much time between us being given the information to go out and procure and get subcontractors on board,” says Coupe.
Due to the time frame and increased scale of the project three separate tower cranes were used on the site. The addition of the two x 600 seat lecture theatres at one end of the site presented a challenge on the finding the appropriate crane-age solution for the site. After assessing different crane options, a hammerhead crane mounted on a travelling base coupled with two luffing cranes was settled on. Coupe says the ability of the travelling crane to move up and down the 30 meters of track gave the flexibility to pick loads out of the two access roads that ran along the boundaries of the project.
Aside from scale and timeframe the complexity of the project lies in the innovative and detailed design.
“Basically nothing is the same size,” says Coupe. “As you work across the structure from left to right and floor to floor every piece is different. It’s not a standard grid pattern and is very complicated structurally. For example we probably have 300-400 different types of precast units.”
The main building rises seven stories and includes a tower, which forms one of the most eye-catching parts of the design. The façade for the tower comprises of three key elements. Firstly a double layer system of external sunscreen glass has been mounted off a curtain wall system. This external sunscreen glass extends up to 5 meters beyond the building to form cantilevered blades on the end of the tower wings. The curtain wall, which encloses the tower, contains 4000m2 of stainless steel spandrel panel.
The main entry is a mix of glass sheets and external aluminium louvres. The roof angles upward into the arc formed by two wings of the tower (which Coupe says was a three dimensional challenge).
The structural glazing system of the atrium is comprised of 600m2 of glass supported by stainless steel tensioned trusses, which are inturn supported off two 18 tonne ‘V’ trusses. The trusses also support walkways that are suspended from the top of the trusses.
Coupe says the façade system for the tower is simply unique and has taken the best part of a year to confirm glazing type, material selection and flesh out the design so that shop drawings could be completed. Nearly 900 shop drawings have been developed so far requiring frequent and intense discussions with the consultants.
The carpark levels also presented construction challenges and contain literally kilometres of in situ concrete walls that had to be built in sequence. Some 4000 m3 of concrete have been poured in the walls alone.
The team working on the site is used to large-scale projects. Coupe says the team came directly from Fletcher Challenge’s last major project, the Auckland Hospital Acute Services Block completed 2003. Between 200-250 guys are working on the Business School site at any one time and Coupe says they thrive on the big jobs.
According to Coupe accuracy was tantamount. Every single precast element, every part of the steel structure and every beam were shop drawn. The construction was broken down into areas and the parts were tracked within each area to avoid confusion.
“Each steel column is surveyed before and after double T’s are placed and each splice is surveyed before the next column section is dropped into place,” explains Coupe.
The resulting building will be both fluid and open providing a strong contemporary look to more traditional style of the beginnings of the University. The aim of the design was to reinterpret the topography of the sloping site and Auckland’s volcanic harbour landforms. Reflecting this, 6 tonnes of black aggregate precast panels (3-4 metres x 1.5 metres) have been used on the podium walls.
“This has the effect of making the tower building stand out like a shining beacon,” says Coupe.
The Business School will be handed over in four parts. Fletcher Construction is just completing part one – the car park level - which will be handed over shortly. This will no doubt present additional challenges as Fletcher Construction constructs the remainder of the building with 1200 cars potentially entering and exiting the underground car park each day. This will be followed by part two (lecture theatres), which will be handed over early next year, part three (teaching rooms) mid 2007 and finally part four (tower) shortly thereafter, says Coupe.
Then in 2008 when it opens for business around 6000 students per day will be flowing in and out of the Business School.
“I think this will be an iconic building because these types of design features haven’t been done before,” says Coupe. “A lot of people are surprised at how big and complex this project is when they see it. We are just about to start on the tower and it’s very exciting. It’s been a long and complex project and I really think by the end of the year people will see it take shape and start to understand what we have been doing for the past 18 months.”
The building is comprised of the following levels:
· Levels P5 to P1: A car park for 1200 cars. Major services plant rooms for chillers, HV, fire and air conditioning plant rooms. A data centre is located on level P1, which serves all of the University campus.
· Level 0: This is the main teaching floor comprising of 2 x 600 seat lecture theatres, 2x 300 seat lecture theatres 1x 150 lecture theatre, 4 x 75 seat case rooms, computer suites and lecture rooms. Several thousand students will be able to be taught at any one time.
· Level 1: This is the main entry level and contains significant outdoor podium space.
· Level 2 to 7: This is the iconic tower that comes out of the Podium at level 1 at the Grafton road end of the site. There are 5 levels of office space, home to several hundred staff and post-graduate students plus a roof top plant room. The tower comprises 3 wings that radiate and curve away from a central core. The curves are accentuated by a series of blades that cantilever up to 5 meters beyond the building line.