The Atmosphere is cool and clear high above Kolkata. Here in this vibrant Indian city a dramatic ‘sculpture in the sky’ is beginning to dominate the local skyline.
Some four years after the vision was first unveiled the dramatic cloud concept is slowly taking shape some 100 metres above ground level.
Deya – which means cloud in Bengali – connects the two towers that make up Atmosphere – a luxury £90 million high-rise apartment project that is the tallest in the growing city and a ground-breaking first for India.
Sitting 100 metres high, Deya also extends 100 metres. With four levels, the highest being the party deck, it will serve as a community space for a very special neighbourhood in the sky.
The structure commands a 360-degree view and will feature swimming pools, a gym, spas, a squash court, a basketball court and a putting green.
There will also be simulation golf, games rooms, a jogging track, a mini cinema, a banqueting hall, state-of-the-art boardroom facilities, an open-air party deck, an amphitheatre - and multiple lounges and spaces for smaller gatherings.
All these facilities will be for the exclusive use of the 80 families that will make Atmosphere’s luxury villas in the sky their home. It is scheduled to open in March 2017.
A team of global experts, including design architects Arc Studio, project architect Edifice Consultants, lifting contractor Eversendai and the world’s leading earthquake engineering specialists Web Structures, has been involved in getting Deya off the ground.
Web Structures has been involved in the complex four year project since day one, devising ways to move it from the drawing board and into the sky.
It brought its knowledge of working on tall buildings all over the world and its collaboration expertise with major architects, including Foster and Partners, RSHP and Kengo Kuma, to the plans for the unique skybridge - which will be lit up by LED lamps at night and will have a 'silver lining' with 15,000 kinetic discs shimmering on its surface.
The structural engineering specialist has worked with the project team to ensure it can stand up to the area’s major seismic and wind challenges.
Dr Hossein Rezai, Web Structures’ group director, explains: “The Deya is not directly connected to the towers. It is a completely separate structure and is allowed to move independently by resting upon four isolator bearings.”
These specially designed earthquake bearings are the biggest of their kind ever designed and manufactured. Dr Rezai adds: “There are two on each tower and each weighs 14.5 tonnes. These bearing sit on concrete plinths that in turn rest on a 200m thick reinforced concrete slab over 2.5 metre deep structural steel girders.
“The bearings themselves are specially designed and tested with energy dissipation to ensure that after an extreme earthquake or high winds that the Deya returns to its original position and the tower structures are not being damaged.”
Dr Rezai says: “Deya ranks among the most challenging projects we have ever undertaken anywhere in the world. The fact is, the skybridge isn’t just a simple viewing platform; it is a complex 2,500 tonne structure with four working levels to it. It’s a sophisticated building in its own right.
“As well as the area’s high seismic and wind challenges we also had to come up with engineering solutions to make sure that any movement of the structure doesn’t cause discomfort to the users and occupants.”
The skybridge construction was carried out in four stages with specialist methods used to haul and hoist it up to its high-rise home. Dr Rezai says: “We chose to construct the two end segments located on top of each tower by installing steel sections piece by piece, this is known as stick building method.
“The mid segment was constructed on the ground using the same method and then it was lifted into place, using strand jacks and high strength steel cables.
“Once lifted there was a gap of a metre between the mid-section and the two ends which had to be welded and bolted together with additional structural steel sections.
“During this 20 day exercise the strand jacks remained in place. Only once all the connections were completed and tested were these released and removed. Then the concrete pouring took place and the remainder of the structure was completed.”
Atmosphere is being created by visionary West Bengal developer Forum Projects. Its emerging development sits on a three-acre plot on the city’s EM Bypass.
DEYA – NUMBERS IN THE CLOUD
Total length: 97.5 metres
Total weight – including concrete slabs, landscaping and swimming pool: 7,800 tonnes
Height at the centre of midsection from ground level: 110.5 metres
Total Midsection Lifting time: 12 hours
Lifting speed = 2mm to 3 mm/second
Amount of steel used: 2,340 tonnes (approx)
Total number of welded joints: 1,090
Total number of bolts used: 30,000