# Khan Shatyr in Astana

Khan Shatyr in Astana
Source: official site

This is my first post about Kazakhstan! I am very happy to be able to talk about this country which I’s like to know! Yesterday I was watching TV and I saw this fascinating mathematical structure in a report about Astana.  Which form has this beautiful roof? Searching information in the official web site:

Quote from MikeSefton, Buro Happold’s project leader of the Khan Shatyr. The center’s design came from the idea of creating one vast roof which would house many venues and which would have a real feeling of space. So often in similar schemes there is a sense of individual, boxed-in buildings but by having one large tent accommodate them all. A major challenge with the project was to keep the temperature inside the space even in a climate with extreme weather conditions. We need visitors to be able to move from venue to venue inside the structure without experiencing dramatic changes in temperature.
Another challenge was the asymmetry of the design. To work to a perfect circle creates a full radial symmetry but when you’re dealing with a cone shape that is also on a lean, you only have one line of symmetry – down the central line. This means every cable anchor and cable has a different geometry as they are all at different angles. Tensile structures are all about anticlastic surfaces – surfaces that have opposing curvatures. Flat tensile designs just don’t work, so if you are considering using a tensile structure, you have to accept that it must have curves.Mountain climbers as part of the construction team. The cable net comprises of 192 radial cables and 16 circumferential cables. The installation of the foil cushions onto the cable net structure which is clad in a three-layer ETFE envelope, will take between three and four months as this can only be done during summer and autumn.To ensure the efficiency as well as to complete the installation of the cables within record time of 1 month, 650 professional mountain climbers from 7 different nations formed part of the construction team at this critical stage. They worked under severe conditions up to a height of 100m from the bottom in order to accomplish the mounting.ETFE – for a comfortable microclimate throughout the year. ETFE (ethylene-tetra fluoroethylene),a material that allows daylight to wash the interiors while sheltering them from weather extremes. The perfect material to be used in unpleasant climates.While the buildings within the envelope are fully conditioned, the target temperatures in the landscaped areas are +15 degrees Celsius in winter and +30 degrees in summer. In winter, a key challenge is to prevent the formation office on the inside of the envelope. This is achieved by a combination of temperature control and directing warm air currents up the inner fabric surface, a strategy that also prevents downdraughts. In summer, fritting on the outermost foil layer provides solar shading. Inside, low-level jets direct cool air across the space, while opening vents at the apex induce stack-effect ventilation.Project’s cable net structure is coated with 19,000sqm of ETFE foil cushions, compromising three layers assembled together, with the middle layer inflated. By inflating the cushions with air the material can accommodate a high thermal range. Each cushion is about 3.5m wide and up to 30m long.The flexibility of the ETFE material also makes it well suited to deal with the cable net’s range of movement. As the structure deflects, the cables move closer together and the cushions change shape – from an eye shape to an almost cylindrical shape.
The ETFE cushion panels are connected to the cables using a system of aluminum clamping plates. These are able to tolerate the movements of the cables under wind and snow loads.

Source: CNN

The 16 circumferential cables hold a picturesqueness structure which must be photographed if a lucky person can travel to Astana. Khan Shatyr Shopping and Entertainment Center is the new symbol of the capital of Kazakhstan. It was designed by Norman Foster and it’s the biggest tent in the World which features shopping and entertainment under the mathematical roof.

Location: Khan Shatyr (map)