Khan shatyr entertainment center

KHAN SHATYRshopping and

entertainment centre,Astana, kazakhstan.

PREPARED BY : RUCHITA DHAMI

CONTENT1. Introduction2. Concept3. Structural design and behaviour

1. ETEF cushion2. Cable net structure3. Tripod

4. Construction1. Eraction of tripod2. Cable installation3. ETEF cushion installation

5. Detail6. Drawings

• Architect - Foster + Partners• Engineer - Buro Happold• Astana, the new capital of

Kazakhstan, is being constructed in an austere eastern landscape with an extreme climate.

• Its remote steppe location to the north of the country experiences temperature below freezing for half the year with extremes ranging from - 40ºC to +40ºC.

1. INTRODUCTION

• Entertainment Center represents a major new civic, cultural and social venue for the people of Astana, bringing together a wide range of activities within a sheltered climatic envelope that provides a comfortable environment all year round.

• The Kahn Shatyr (Big Tent) provides 100,000m2 of floor space where the people of Astana can meet, shop and relax year round in comfort despite the extreme environment.

INDOOR BEACH

SHOPES &

CAFES

`

INTERNAL PARK

ENTERTAINMENT EMINITIES

• Creating a giant, free-spanning enclosure with the minimum of support.

• Single-masted cable net in a conical form was their natural choice due to its simplicity and efficiency of material.

• With a single compression mast to lift the net and create a large volume underneath, the roof skin is in tension and can use cables rather than beams to carry all loads.

• It also creates a very strong “iconic” form on the skyline – a critical consideration for such an important building in the capital city.

2. INITIAL CONCEPT

• The 19,000m2 transparent roof of the Entertainment Centre comprises ETFE (Ethylene tetra fluoroethylene) cushions supported on a cable net structure.

3. STRUCTURAL DESIGN

3.1 ETEF cushions

• The skin of ETFE cushions is very lightweight and insulates while still providing natural daylight.

• The cushions are flexible to accept the large deflections of the cable net, however their frames are much more rigid, and so they decided a staggered arrangement of cushions.

• This allows the hoop frame of one panel to squeeze in on the mid point of the adjacent panel and benifit from the inherent flexibility of the cushion.

3.1 ETEF cushions

• Each tripod leg is formed from a three chord truss with 1000mm diameter circular hollow main sections, the back leg resists 140MN while each front leg resists 50MN.

• The legs meet at a hub which supports 12 pin ended struts reaching to the cable net top ring.

• The hub is located so that its centre line corresponds with the resultant axial force from the cable net under prestress loads.

3.2 Tripod Structure

• The roof cables are collected 90m above ground on a ring at the top of the steel tripod and span to the sloped concrete perimeter which forms the base of the building.

• The shape of the cable net is based on a classic cone which has been pulled over to one side.

• This gives the Entertainment Centre its distinctive sloping architectural form.

3.3 Cable Structure

Conceptual sketch by norman foster

• Radial cables span from the top ring of the steel compression mast to the outer concrete perimeter and are prestressed against hoop cables to form an anticlastic surface.

• 192 pairs of 38mm diameter radial cables vary in length from 125m at the front of the tent to 70m at the back.

• The hoop cables are arranged perpendicular to the ridge line of the radials.

• A relatively high prestress of about 80% of the peak cable forces is utilised in the tent to control deflections to around 800mm over the longest cable span.

3.3 Cable Structure

• The tripod provides the single point of support to the centre of the cable net and is an important element for the architecture of the building.

• Traditionally the central support of a conic tent is a single mast, pinned at both the top and the bottom and stabilised by the tent that it supports.

• This only ever places axial force in the mast which moves with the tent under asymmetric loads and reduces the peak tensions within the cable net.

3.3 Cable Structure

• However, it was felt impractical to temporarily support a fully articulated 150m high single mast during construction so this principle was adapted for the Entertainment Centre.

• The tripod structure which is used provides a robust constructible base while the articulated top ring that it supports provides some movement to relieve the forces in the cable net.

• The movable part of the mast is then a much smaller element that was easier to temporarily brace during construction.

bracing

• The greatest challenge to overcome in the construction process was the erection of the tripod.

• The general arrangement of the tripod was configured to allow a dramatic single lift process where the whole 1,700 ton tripod was pivoted around pins at the bases of the two front legs.

4. CONSTRUCTION4.1 Erection Of Tripod

• Strand jacks, attached to the top of a temporary tower in front of the tripod, pulled on lifting cables attached to a frame

on the tripod hub.• As the front legs pivoted up, the top

of the back leg lifted on a temporary pin connection under the hub whilst its base slid in on a bogey running on a rail track.

• Temporary bracing to the cable ring remained in place until the cables had been installed and correctly prestressed.

• Although the tripod provided the most dramatic sequence in the construction of the Khan Shatyr, the installation of the cable net was also challenging.

• The radial cables were lifted individually into a slack condition with cable clamps attached ready to accept the hoop cables which were placed over the top of the radials.

4.2 Cable Installation

• Once all the cables were in place tension was pulled into them using a jacking detail at the base of the radial cables to bring the net into shape and allow the installation of the cushions to proceed.

• The ETFE cushions were slid into their extrusions from the base and pulled through to the top.

• The length of the cushions were maximised to reduce their number and make the installation as fast as possible, but during the winter months the cold temperatures made the ETFE much harder to work and tension.

4.3 ETEF Installation

5. JOINARY DETAIL

SITE PLAN

FLOOR PLAN LEVEL 1

FLOOR PLAN LEVEL 2

FLOOR PLAN LEVEL 3

FLOOR PLAN LEVEL4

FLOOR PLAN LEVEL 5

SECTION