Guangzhou TV Tower

Architectenweb Magazine as Media

On the 6th of May the construction of the Guangzhou TV and sightseeing tower reached its highest point. The total construction took 4 years and is set to be completed in a few months. The tower was designed by Dutch architects Mark Hemel and Barbara Kuit from Information Based Architecture. Their collaboration with the engineers from Arup resulted in a joint entry which won the design competition in 2004.

The principle of the form is simple: One ellipse at ground level and a smaller ellipse, which forms the roof, are connected by columns. The ellipses are twisted in opposite directions and a lattice structure is added. The tightening caused by the rotation of the tower forms a characteristic waistline which gives the tower a feminine and elegant shape. Spatially, the tower appears as a series of mini-buildings hung within the superstructure. As a result, the 610m high tower has 37 functional floors. The mini-buildings contain a restaurant, a 4D cinema and several viewing platforms. The highest viewing point is at 459.2m.

SKYWALK The lower floors contain the functional workings of the tower. The infrastructural connections, ingraining the tower in the city’s structure, include a subway and bus station, footpaths and a parking area. The lower floors also house commercial spaces. The first mini-building is located at a height of 75m and contains two cinemas, play halls and a tea room. On the roof of this mini-building, at 117m above ground level, is a sky-garden. On the roof of the next mini-building, at 168m, the Skywalk starts: this open staircase allows visitors to climb the tower up to a height of 350m.

On the Skywalk, the visitor is surrounded by both the view and the spatial structure: a set of stairs, a concrete core and a surrounding grid of columns, rings and diagonals. The core and the ‘façade’ are connected and together they form the supporting frame of the tower. As for the buildings, they are connected by the floors. Horizontal concrete joints were added to the skywalk to increase stability. The surrounding grid consists of 24 columns, 46 rings and 24 diagonals. Inside the tower, the rings dominate the views. These rings, with an 800mm diameter, are attached to the columns by a joint. They come away from the columns and appear to float.

NODE Technically speaking, the point where columns, rings and diagonals connect - the node – is the most essential element of the tower. Also, this node made the construction financially viable. In the original design, the grid was entirely random with hundreds of different nodes as a result. In the final design, all 1,100 nodes are based on the same basic connection. As a result of the rotation, a number of parameters differ, such as the diameter and the thickness of the various bars and the angles which they create. During the design stage it appeared that the costs for the nodes, and thereby the costs for the entire tower, could be greatly reduced by keeping the angle between the bars at a minimum of 25 degrees.

PARAMETRIC DESIGN The detailed design for the tower was created with parametric associative software. Boundary conditions were set for three criteria: strength, rigidity and maximum vibration permissible. By varying geometric parameters, models can be calculated of their effects on the tower. The parameters for which the effects of distortion were modeled were: the rotation of the roof in comparison to the ground level, the number of rings and the openness of the structures.

The models were created in order to calculate the minimum amount of materials needed to meet the criteria set for the tower. The tower needed to be able to meet these criteria, even under extremely demanding circumstances such as typhoons and earthquakes. The more open the structure, the less the load generated by wind. As a result, the scattered placement of the mini-buildings had a positive influence on the load distribution. Dampers needed to be installed in two places in order to meet the requirements set for vibrations. These requirements were set to increase safety as well as the sense of security for the visitor. The calculations were confirmed by wind tunnel tests and earthquake simulators.

STRAIGHT AS A N ARROW Although the rings are characteristic for the interior, the 24 columns form the eye catcher on the outside. They appear elegant and curved, but in fact they are dead straight. The columns consist of 3.7m prefab slabs. On the lower floors, the columns are 2m in diameter. The manufacturer ‘rounded’ and welded the 5cm thick steel plates. Towards the top of the tower the wall is 3cm thick and the diameter decreases to 1.1m. Although the original design features a gradual benched decrease , the final design shows the columns gradually narrowing, thereby reinforcing the elegant appearance of the tower. The column sections were stacked and joined on site, as were the columns, rings, diagonals and nodes.

After the various bars were leveled precisely, the seams were welded open and the bolted joints removed. Next, concrete was poured into the smooth columns for extra stability and fire resistance The concrete core, which houses the lifts and staircases, was entirely poured in table formwork. The tower is adorned with a antenna, which levels with the highest building in country.

world’s tallest TV tower opens its doors

Information Based Architecture as Architects

Canton Tower After 6 years of design and building works, on October 1st 2010 the Canton Tower has opened its doors to the public. Mark Hemel + Barbara Kuit and their Amsterdam firm, Information Based Architecture, designers of the tower, are pleased to announce that world’s tallest TV and Sightseeing tower is now a fact. The Canton Tower is Guangzhou’s most important new building and will represent the 10 million inhabitants counting metropolis as a cool, progressive and exciting city. Guangzhou is now ready to host the Asian Games that will take place in November 2010. The world’s tallest TV tower - reaching 600m in height, is bypassing Toronto’s CN tower, and is hoped to attract 10 000 visitors daily.

Supermodel Mark Hemel, IBA architect and director, comments, “ Where most skyscrapers bear ‘male’ features; being introvert, strong, straight, rectangular, and based on repetition, we wanted to create a ‘female’ tower, being complex, transparent, curvy, gracious and sexy. Our aim was to design a free-form tower with a rich and human-like identity that would represent Guangzhou as a dynamic and exciting city.” The result is a tower, very slender and tall, that bears similarities with the figure of a female, the very reason that earned the nickname: ‘super-model‘.”

Twisting The idea of the tower is simple. The form, volume and structure is generated by two ellipses, one at foundation level and the other at a horizontal plane at 450 metres. These two ellipses are rotated relative to another. The tightening caused by the rotation between the two ellipses forms a ‘waist’ and a densification of material.

Organic Concept The structure consist of a open lattice-structure, built up from 1100 nodes and the same amount of connecting ring- and bracing pieces. Basically the tower can be seen as a giant 3 dimensional puzzle of which all 3300 pieces are totally unique. Architect Mark Hemel comments: “Recent State of the Art fabrication and computerized analysis techniques allow designers to create much more complex structures then ever before.

The Competition The international competition was held in 2004 for the design of the tower, a 17.9ha park at its base and the master-plan for the surrounding 56.6ha which includes an elevated Plaza, pagoda-park, retail facilities, offices, television centre and hotel.

Programme The Canton Tower consists of 37 floors of programme including exhibition spaces, a conference centre, a cinema, 2 revolving restaurants and one VIP-restaurant, various cafés and observation levels. A deck at the base of the tower hides the giant building’s infrastructural workings. Public transport connections including a metro and bus station are met underground. These levels support other facilities as well, including exhibition spaces, a food court, extensive commercial space, a 600-vehicle parking and tourist coaches. Panoramic double-decker lifts serve both entrance levels.

Sky-walk Between level +170 meter and level +350 meter there is a “skywalk”; an open-air staircase will lead the public all the way up through the narrow waist of the building.

Outdoor Observation square From the upper observation levels it is possible to ascend even higher, via a further set of the stairs, to a terraced observation square at +460m, rising well above the tower’s top ring, one can have a panoramic view over the booming city of Guangzhou. A set of capsules circumvent the perimeter of the top ring, offering visitors breathtaking views over the very edge of the building.

Progress Since the initial winning of the scheme, the design has been developed over several years. Many tests were done to check the safety and strength of the structure among which wind tunnel-, fire- and load tests. The groundbreaking ceremony took place in November 2005 after which the foundation and piling were constructed. The steel structure of the main building was completed in November 2008. The building was finally topped out in May 2009. The Canton tower now opens its doors, in order to be fully operational for the 2010 Asian Games.

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