Thrill seekers in Abu Dhabi will soon have more than the Gulf state’s Formula One race to enjoy. Jessica Rowson reports on the construction of the world’s largest indoor theme park at Yas Island.
Abu Dhabi’s Yas Island packs in an awful lot of excitement. It is already home to the Gulf state’s Formula One circuit and later this year Ferrari World, the world’s largest indoor theme park, is due to open. And while the thrill seekers will delight at the huge number of exciting rides, it is the soaring red roof of the park that will get engineers’ pulses racing.
The form of the Ferrari GT 250 inspires the shiny red, double curvature roof. There are four independent roof structures, a central circular section that dips into a central funnel and three legs or “tri-form arms”, which stretch out equilaterally from the central core, providing shade for the rollercoasters and rides that wind their way out from the main play area.
“Essentially the structure falls into four sections − a central form around 350m in diameter and three tri-form arms,” says Ramboll director Alasdair MacKerron.
“The building is big − it’s around 750m from one of the three outermost points to the next.”
Everything radiates from the central glazed funnel or well, which was introduced to allow daylight into the centre of the building.
A central ring of columns around this funnel supports the main roof and these extend up and outwards as beams to the edge of the central section to form the main radial lines of support.
“The building is big − it’s around 750m from one of the three outermost points to the next”
They are supported at the outer edges of the central section on V-shaped columns and also halfway between the V columns and central columns by another line of columns that keep structural spans to around 75m.
Structural isolation joints separate the four different roof structures, which allow the roof sections to move independently under seismic and temperature loads.
The original design incorporated steel girder beams, but as the design developed, it evolved into a space frame structure − a truss-like, lightweight rigid shape constructed from interlocking struts.
The space frame is slightly deeper in the areas where the girders were originally intended to be, maintaining the feeling that everything is radiating from the centre.
“The roof is a space frame,” says MacKerron. “The initial scheme design had steel girders with the roof lifted into place to get clear spans and minimal temporary works.”
The overall roof structure covers some 700m in diameter and represents a threedimensional arc area of more
201,000m2. The three tri-form extensions create shade for the primary facades and provide protection to the rollercoaster areas.
“With the tri-forms, they’re not having to span so far [as the central section] and are quite narrow,” says MacKerron.
“They’re supported on one side as they come down to the ground.” Inside the park, there are three levels of reinforced concrete slabs.
The ground floor is earmarked for back-of-house activities but the first and second floors are where all the action really happens − water flumes and rollercoasters.
“We’ve designed the structure to take the load for all of these and the ride simulators,” says MacKerron.
Below the main roof are 19 separate buildings housing the individual rides and attractions, constructed from in-situ reinforced concrete, with composite steel and concrete floors and roofs.
There are two roller coasters in the Ferrari World. One is a Formula One coaster that accelerates its cars to over 200kmh in just over 4 seconds. The other is a twin-track duelling GT coaster, which allows riders to “race” against adjacent cars.
“It’s a balancing act − if you make the piles too stiff, you put stresses into the steel frame”
Ramboll had to design foundations for the rollercoaster rides. This was difficult in the sandy ground conditions as the ground in this area is made up of sands of increasing strengths with some thin mudstone layers.
The rollercoaster foundations are subject to cyclical loadings each time the coasters run. With each loading, the piles move a small amount and thus move or compress the adjacent soil.
“The foundations for the rollercoasters were really challenging. The piles sit in the sand, but you can’t rely on the passive pressure, because it’s a dynamic load and so the movement could dislodge the sand. Therefore you need to design the piles to be quite stiff, but it’s a balancing act − if you make the piles too stiff, you put stresses into the steel frame.
“If it’s too flexible, it adds movement and could make the rollercoaster too lively.”
Conventional piled foundations of 750mm diameter were used for the main building with 900mm and 1,200mm diameter piles used for the roller coasters.
As Ferrari World is on a greenfield site, extensive pile testing was carried out to confirm geotechnical properties.
Heat was also an important design issue. The main reason the theme park is indoors is because of the Middle East’s uncomfortably hot climate, something that could certainly deflate the fun factor.
“The façade team were involved in developing the materials,” says MacKerron. “The roof is insulated to keep the heat out.”
The tri-forms also provide shade for a lot of the perimeter façade.
The first pile was driven in August 2007. At that time the Yas masterplan was a blank canvas waiting to be turned into the grand vision for the island.
The primary shell and core works were completed at the end of last year and the installation for the rides and attractions is ongoing. The grand opening of the park is planned for the second half of this year.
D&B Contractor Mero
Main contractor Sixco
Rides & attractions JRA