|Client||JP van Eesteren|
The Market Hall is an architectonic residential project and market hall in Rotterdam, designed by the world-renowned architectural office MVRDV. The concept and typology of the building are readable from the iconic shape. The combination of an apartment building covering a fresh food market with food shops, restaurants, a supermarket and an underground parking is found nowhere else in the world. For the Netherlands the realisation of this new hybrid public building also means the first covered market. The building needed to be as open as possible to attract the public and at the same time it had to be closed off due to weather conditions. This resulted in a spectacular design covering the front and backside with a flexible suspended glass facade, allowing for maximum transparency and a minimal structure. These transparent cablenet facades have a width of 42 meters and a height of 34 meters, the largest of its kind in Europe. Octatube has been responsible for the engineering, production and installation of these large glass facades in collaboration with: Provast (Client), JP van Eesteren (Main Contractor), RoyalHaskoningDHV (Structural Designer), MVRDV (Architect) and Inbo (Interior Architect).
The glass facade is divided in 26 vertical and 22 horizontal cables. Together they form a suspended net, similar to a tennis racket that functions as a single layered load bearing structure. The cables are pre-stressed between strong (60 mm thick) steel boxes embedded and cast in the concrete walls. The boxes have been designed in such a way that rough concrete tolerances could be transferred into tight tolerances needed to construct a glass facade. The galvanized steel cables run through spherical joints to allow for deformations and prevent material fatigue. All cables have a diameter of 31.3 mm, and their breaking strength is 884 kilonewtons. One of the technical challenges for the structural facades of the Market Hall, is to deal with the high pre-stress forces that have to be transferred to the concrete arch. The cables are prestressed to a maximum of 300 kilonewtons each, of which 50 kilonewtons is in fact surplus capacity to deal with the consequences of creep in the concrete.
A cast steel node is placed where the cables cross each other, allowing the vertical and horizontal cables to intersect while fastening the corners of the glass panels in one single detail. The distance from the horizontal cables to the glass is 150 millimetres and the distance from the vertical cables to the glass is 100 millimetres. Laminated single glass units, with a typical dimension of 1485 by 1485 millimetres, are fixed to the cables by means of circular clamping plates. In the middle, the facade can be exposed to deflections up to 70 centimetres during extreme wind loads. A horizontal deflection of a facade with such tolerances is one of the characteristics of cablenet facades.
The deformation causes the cables to elongate and the glass panels to rotate up to 5.4 degrees. In the corners of the facade where 2 sides of the glass panels are more or less fixed, one corner can move inwards and outwards up to 50 millimetres. The detail of the door portals is also interesting: the portal frames are moving with the facade disconnected from the revolving doors.
The main structure of the cablenet facades consists of galvanized steel cables, cast clamping nodes and steel plates for the embedded boxes. All cables in the facade are of the same type, but the theoretically required pretension force is different for each cable. For practical reason the cables’ pretension forces have been distributed and grouped per five adjacent cables. In addition, a very specific pretension protocol has been written to gradually and uniformly load the concrete arch. The cables are - without pretension - too short to fix them directly at both sides. Therefore, the cables have been fixed at one side, while a temporary tension bridge has been used at the opposite side. After installation, the cables have symmetrically been pre-stressed for 50% by means of hydraulic pretensioning, after which a second round of pre-stressing has brought the pre-tension in all cables to 100%. During this operation the cables have all been stretched between 94 and 147 millimetres each. The maximum applied tensile force of 300kN can be compared to 20-25 middle class cars. The typical glass panel is 1485 by 1485 millimetres, composed of clear heat-strengthened float glass. The single glass units are laminated with two panes of six millimeters. It has been a deliberate choice from the architect not to apply any coating on the glass. The main consideration for this has always been to maximize the sense of openness and transparency. The two facades both have a total glazed area of 1258 square meters.
The Market Hall was opened on the first of October by Queen Maxima. Ever since the opening the building has attracted ongoing publicity. There are hundreds of favourable reviews from both the international architecture platforms and international media such as The Guardian and The New York Times. The realization of the building has also played an essential role in strengthening the reputation of the city and the brand of Rotterdam, now named as one of best cities in the world for travellers to visit. In the first few weeks the Market Hall had already attracted one million visitors. The exterior facade is clad in grey natural stone; the same is used for the market floor and the surrounding public space, in this way the emphasis lays on the colourful interior. The large mural has been rendered in the Pixar Studios and covers the vaulted interior. Especially at night the 11.000 square meter interior painting, called ‘Cornucopia’ or ‘The Horn of Plenty’, comes alive. This sensation is enabled by the transparency of the cable facades with only nine kilograms of structural steel per square meter. The success of the Market Hall may lay in the synthesis of a new urban mixed-use building typology, bold architecture and a spectacular interior artwork. The cable facades facilitate these aspects.
Not only has the building already won several prices, but also the cable facades are awarded with the Dutch Construction Awards 2015 in the category for building materials and –systems. The jury praised the synergy between structure and architecture as well as the guts and intelligence of the engineers. Cable facades are an emerging trend in architecture. They are the perfect tool to create very transparent facades of which the Market Hall's cable facades are a prime example.