Italianità, German backstage engineering, Chinese pragmatism – can that work?
During the realization of Terminal 3, the planning cultures of three different types of mentality collided: the artistic talent of the Italian architects, the technical expertise of the engineers from Stuttgart, who were part of the team from the very beginning of the competition, and the Chinese Design Institute. In 2008 it had realized Terminal 3 of Beijing Capital International Airport in collaboration with Foster and Partners (see DETAIL 7/8 2008, p. 791–797), more than twice the size of Terminal 3 in Bao’An.
With the exception of the airport specialists Foster and Partners, gmp and Kisho Kurokawa, architect teams that hadn’t built airports yet were also invited in 2007 to participate in the competition: FOA, Reiser Umemoto, and Studio Fuksas. The principle organizational structure and the building footprint, including the placement of the terminal and the cross-like arrangement and distribution of functions across multiple levels, had already been determined by the client and a Dutch specialist. The planning teams’ task was to transform this structure into a spatial event and an unmistakeable landmark. In a subliminal way, the clients expected an emotional building, able to outshine the rational appearance of Hong Kong International Airport, 25 miles away. Within the Pearl River Delta, the world’s most productive urban agglomeration, the former British crown colony with its rich traditions is the strongest rival of Shenzhen, founded only in 1979 and by now the fourth largest metropolis in China.
Spatial event via high tech?
A coherent concept for building structure and facade, climate control and daylight optimization technology, as well as interior design with all inbuilt elements and shops etc. developed ready for construction is an integral part of the architects’ work. After numerous rounds of decision making via workshops, four applicants remained. Five months later Studio Fuksas in team with Knippers Helbig Advanced Engineering prevailed against Reiser Umemoto’s perforated reinforced concrete steel tube. In China, interpersonal trust and persuasiveness are more important than comprehensive lists of references on a sheet of paper. Their design fills the technical construction task with life; it creates differentiation within the strict geometry of the longitudinal concourse via indentations and large skylights within the roof construction. The project becomes a scenography of the passengers’ movements - from the subway right into the airplane. The idea is to evoke different and varying light situations reminiscent of forest clearings. In a preceding oval shape of 245 m length and 160 m width serving as traffic centre, passengers emerge from the below-grade regional and long distance bus and rail connections. By crossing a bridge on Level 1, they reach the lower, two-story area of the terminal hall (ill. 3). The conveyor systems of the grand, two-story baggage claim area are located behind the safety barrier. The true vastness of the building becomes apparent on Level 3. Here, the four-lane ramp directly connects to the departure hall and its columns, conically increasing in diameter and lifting the space to a height of up to 25 m (ill. 11). This part of the building is 306 m long and 642 m wide. Its volume and double skin continually decrease in plan and section along the central axis – the longitudinal concourse – similar to a bottleneck. Level 1 of this three-story building section houses international arrivals. Here, the double skin of the building envelope can be experienced solely along the longitudinal elevations (ill. 24). However, the steel construction shows off its full impression via simultaneous views to the runway and the sky through the two skins of the facade. It bulges outward, spanning a width of 45 m at the supports and increasing to 61 m, while maintaining a clear height of 23.5 m from the supports to the underside of the construction. In order to structure the seemingly endless spatial expanse of this 760 m long tube and turn it into a diversified spatial experience with defined places, the structure curves inwards in five areas. The interior skin reduces the volume, while the glazing of the exterior skin increases brightness via generous skylights. Halfway through the building, the crossing of longitudinal concourse and lateral concourse provides another point of orientation: The architects interpret this hub for arrival and departure of domestic flights as an urban piazza. Info-point and bar are supposed to offer urban flair. Escalators are arranged along recesses that provide visual connections across all three levels. While the cross section of the longitudinal concourse delineates the point of intersection continuously, similar to the fuselage of an airplane, the sections of the flanking lateral concourses taper inward towards the intersection point, reminiscent of wings.
Curved megastructure versus honeycomb
Two creative principles determine the design: the building form and the sculptural “tree trunks” of the ventilation shafts feature organic curves, while the exterior and interior skin of the steel construction are subdivided into geometrical honeycombs. Designed according to principles of fractal geometry, the inbuilt elements for internet point, check-in counter, security and passport check and gate counters, also designed by Massimiliano and Doriana Fuksas, are shaped as honeycombs at different scales. Their polished stainless steel surfaces magnify the prismatic play of light in a kaleidoscope-like way.
From free-form clay model to mathematically describable geometry
Similar to design studies in automobile construction, the architects created clay models of different versions at 1:1000 scale for internal discussion and clarification of the building volumes. The be-all and end-all is the final clay model and the corresponding 3D surface model, created with the program Rhino. For the design work to follow, the inclusion of numerous professional consultants, submitting the project to the client and finally the transformation into individual construction components by various firms, these free-formed surfaces need to be translated into a mathematically describable geometry. Knippers Helbig converted the architects’ NURBS-based surface model into a geometrically discrete basis comprised of evenly distributed control points (ill. 18). The control points also form the origin of the parametrically developed geometry of the honeycomb-shaped, three-dimensional sheet metal glazing and elements of the load-bearing spatial grid, dimensioned according to parameters of daylight intake and visual connections (ill. 20).When planning began in 2008 the development of programs such as Grasshopper was still in its early stages. So Knippers Helbig had to develop several parametric software solutions themselfes. Bao’an Airport Terminal 3 is the world’s first building at this scale that employed this technology. The geometric data are also made available to the corresponding specialists to create daylight simulations or calculations of solar energy intake.
Clear definition of responsibilities
These control points are precisely defined as x-, y-, and z-coordinates and are submitted to the client in the form of Excel tables instead of conventional plans (ill. 17). In addition to a sheet metal list for the building envelope these data are sufficient to describe the facade. Three-dimensional visualizations serve only for internal control (ill. 13). In Western Europe and North America planners avoid to submit these sensitive data due to liability reasons. In China, however, after an in-depth design phase and a handover procedure supported by multiple workshops, liability is entirely conferred to the Local Design Institute (LDI), in this case BIAD. Design architect and engineer completely surrender their responsibility, but can still be included in consulting or supervisory roles hereafter. The previously established data model serves as reference until realization – this saves costs and time within the programming undertaken by successive planners and firms and reduces potential errors along interfaces. After the design phase the project is completely in Chinese hands. This is decisive for maintaining the tight schedule. The local design institute, perfectly accustomed to comparable tasks, adapts the detail planning to local construction practices, economically inconsistent framework conditions and the capacity of contracted construction firms. In the case of shortages it can draw from up to 6000 staff members.
Structure follows facade
With the honeycomb structure of the facade as basis, the geometry of the spatial grid follows the diagonal lines of the building envelope in order to avoid obstructing visual connections through the double skin facade that can be caused by horizontal and vertical structural members. A rhomboid spatial frame, however, can’t provide adequate lateral bending resistance. The engineers dissolved the required solid stiffening arches at 18 m intervals into two parallel, filigree lattice layers of “twin bearings” in order to ensure transparency to the highest possible degree (ill. 26 –30). The connecting support is cast – at this scale, an innovation in China (ill. 28). The steel structure is placed on the solid reinforced concrete pedestal. The supports have to tolerate the thermal expansion characteristics of both materials and absorb shock-like stress from horizontal movements caused by earthquakes as well. Plate springs, gradually elastic from centre to rim, synchronise these impacts along all supports and provide earthquake proofing.
When it comes to node design, two cultures clash: the German engineers, following their “Stuttgart philosophy” of design, generate flexible joints via targeted changes in cross-sectional dimensions in order to avoid unnecessary stress. Their Chinese colleagues at BIAD, on the other hand, follow the reverse principle: strong node – weak member. This means that the overall structure remains stable even if a single bar fails. The German principle, based on adhering to elastic-plastic deformation and utilising the potential of rearrangement of stress within the structural system, is more efficient, yet more complex in terms of calculation. The Chinese principle of plastic connections for fixed support of connecting construction components along a very stiff node isn’t as elegant. However, it has proven itself as a superordinate safety philosophy within the rough and tough of everyday Chinese construction practice – of Terminal 3 as well as the National Aquatic Centre or “Watercube” in Beijing (see DETAIL 7,8/2008).
The design of the facade changed during the course of development, in addition to the entire concept for climate control and sound proofing against aircraft noise. Following initial proposals for a comparably simple facade adapted to circumstances of production in China, a solution based on Western standards and comprised of sandwich panels and an insulated interior skin with glazed daylight apertures was to be analysed as well (ill. 10 a). The climax of the international financial crisis was also experienced as a shock in China in September 2008. While the project never reached a stand-still, minimising the project was discussed, yet dismissed. Finally the decision was made for a technically simplified and implementable solution based on locally available manufacturing methods that had proven effective in the case of the construction of the Beijing Opera Theatre (ill. 10 b). Even in China it is impossible to find a single firm that can enclose the 250,000 m² of surface in the required time both on the interior as well as the exterior. For reasons of capacity three firms are contracted to realize the key details in two different versions for the terminal and the concourses.
Outlook
In China, planning processes are handled professionally and in the shortest possible time, due to the large number of mega-projects. Decision-making can take place within a closely knit web of actors, mostly devoid of the control mechanisms typical for democracies – with all the related advantages and disadvantages. At this point, standards and codes still have to be developed. Questions that arise within mega-projects subsequently become research projects at universities, their results integrated within these standards. What does this mean for Western planners and constructions firms interested in working in China? The German engineers were required to submit binding design loads for the entire roof construction only shortly after the competition, due to time constraints and since construction of foundations was scheduled to take place in follow and without much delay. Meetings in which questions are discussed in plenum are replaced by tightly set submission deadlines. The submission of the huge amount of data becomes a difficult task for one German representative, sitting across the table from 25 Chinese clients. Instead of interpreters, the parties involved communicate via email in order to minimise misunderstanding or translation mistakes via written communication. The construction site becomes the interim settlement space for thousands of migrant workers – numbers of up to 30,000 have been reported – who work, eat and sleep right at the construction site. Until 2025 the capacity of Terminal 3 is supposed to be increased to 36 million passengers per year by adding two further cross-like structures with longitudinal and lateral concourses as satellite buildings. This increase is projected to rise to 45 million passengers per year in 2035.
However, the architects and engineers of the German-Italian planning team will not be involved any further in these mega-construction sites. All the more they can now relax and enjoy the image of “their” Terminal 3 as airline passengers approaching this “manta ray that transforms into a bird and ascends into the skies.
