Main Hall Lyon-Satolas Airport

Lyon, France
Santiago Calatrava, architect

Location

History

The new portion of the Lyon-Satolas airport, designed by Santiago Calatrava from 1989 to 1994, responds to the existing airport built by Guillame Gillet in the late 60's. The response was to continue the notion of a central concourse flanked by two symme trical wings. Calatrava's design is composed of a main hall, two wings for accepting train, car and bus traffic, and also a gallery leading into the main airport building. The hall is triangular in form with two balconies that cantilever into the centra l space. The concourse wings extend 500 meters to both the northeast and southwest, while the gallery reaches out to the southeast over a distance of 180 meters.

The idea of this design refers to the metaphor of a bird, expressing flight and a sense of lightness. The use of steel for framing seems to be an appropriate choice of material for carrying our the feeling of flight. There is also an expression of plast icity exercised in the structure of the main hall; this idea was explored early on in the design process through sculptural media.

Physical Description

The main hall is the most dynamic of the three elements designed by Santiago, although it maintains a simple geometry. The hall is axiated by a central spine which is generated by two cones that intersect at the transversial axis of the station. Two mor e cone shapes extend from the central backbone to create the 'wings' of the 'bird'. The central spine is formed by three arches braced together by diagonal beams. The spine is supported by a concrete mass on the east and two suports (integrated with lif t towers) on the west. The uppermost arch of the spine is a steel box of tringular section while the two lower arches are composed of steel tubes. The cross bracing members vary in size and are assembled four by four along the central tubes. This confi guration forms a series of triangles along the surface of the spine, forming the backbone of the 'bird'. The planar triangles are glazed and the deformed triangles are enclosed in a self-supportive cladding system which includes a thermal break, acoustic insulation and weathering details.

The 'wings' of the bird are composed of 'wing-tips' of varying height creating a fan-like growth springing upward from the ground. Each 'wing-tip' is supported at three points: the lower part is supported by the tubular arches of the spine, the central p art rests on vertical columns (which also carry the lateral glazing), and the hightest part is supported by a 'leg' which is attached to a triangular lattice beam and descends to the feet of the columns. These columns are linked together at their tops to form the curved triangular lattice beam which spans the width of the main hall. The inclined lattice arch consists of a double I-section at the upper point and a tube at the lower point. Essentially, the structure of the 'wings' can be broken down into a series of bays, eahc composed of a 'wing-tip', a facade column, and an articulated 'leg'.

Building Process

The overall structural system was generated on AutoCad which provided the basis for structural calculations. Wind tunnel tests were also performed before making final decisions. As a result of these, the extremities of the wing tips were left void in be tween to limit wind turbulence forces. The entire design was executed with complex steelwork by steel contractors Eiffel. Each bay was erected in two stages: first, the lower wing tip, lower leg and column portions and secong, the upper wing tip and upp er leg.

Structural Descripton/Aspects

The main loads which the main hall will be required to carry and resist are the dead load of the weight of its own structural and non-structural members, and live loads such as large crowds of people at peak traffic times, rain and possibly snow, and late ral live loads such as wind and possibly earthquake forces.

Lateral Loading
A large portion of the lateral loads will be imposed onto the north and south glazed facades underneath each 'wing'. The lateral glazing itself is supported by each facade column, however it doesn't seem likely that these columns are supporting all of th e lateral live loads. When this structure experiences wind loads from the north and south, the lateral forces are sent through to the triangular lattice arches as well as to the central 'spine' form. Each facade column is connected at its highest point and linked to its neighboring column by the steel members which make up this lattice beam structure. The triangulated shaping of the spinal cross-bracing beams help to develop lateral stability of the structure as a whole.

The form of the main hall itself also helps to resist lateral loads because it is triangular and doesn't allow for lateral loads coming from one direction to dominate any part of the structural system. The triangular form helps spread lateral loads evenl y to three main points which meet the ground, rather than allowing these forces to become concentrated which might begin to cause upturning or shear. The repetition of each structural bay and the repetition of the triangular form help to create a whole s ystem which is able to accept loads from any direction. The fact that this hall is surroundsd on three sides by extending concourse wings is also to be taken into consideration when viewing its lateral stability.

The design of the concrete mass embedded in the ground at the east shows consideration of upturning forces. This piece has been toothed with a jagged edge base. Such notching can help resist porticular forces such as upturning or extreme tension stress.

Vertical Loading
Vertical loads within the main hall are accepted and supported in various places. The roof facade columns that help to create the fan-like 'wings' send loads from the 'wing-tips' and roof structure down to a concrete arch which supports all of the column s at their base. The columns are evenly spaced along this concrete arch, supposedly creating an evenly distributed load. However, each column is carrying a different load as each sectional bay varies in size and form slightly. this concrete arch then t ransfers the loads outward in either direction into the ground. The facade columns also support the facade glazing, which is attached directly to these primary columns without any secondary structural pieces.

The central 'spine' of the main hall is formed by three arches braced togther with diagonal beams and terminates at the eastern end into a large concrete mass and at the western end at two supports. These supports are integrated with lift towers which le ad to parking underground and help compose foundation footings. the concrete mass and supportive lift towers are accepting the vertical loads coming down through the three arch forms and transfer these forces into the ground. The three 'spine'-forming a rches are supporting the form of the central portion of roof structure as well as live loads which will be incurred.

If we were to look at one bay of the 'wing' facade of the main hall we would be viewing three main structural members which compose each section to form the overall 'wing'. Each bay consists of a 'wing-tip', a facade column, and an articulated 'leg'. Th e 'wing-tip' is the member which extends freely into space, therfore, supporting no vertical loading on its own. This 'wing-tip' is supported in three places: by the tubular spinal arches, the vertical facade columns and the 'leg' which is attached to th e triangulated beam. Each of these three connections transfer forces coming from the 'wing-tips' and send them downward into the earth. The arches which meet each 'wing-tip' at its lowest point take the vertical forces and spread them to the terminating points at either end of the entire structure. The connection between 'wing-tip' and facade column occurs at the mid-point of each 'wing-tip'. Each facade column then takes the load coming from the 'wing-tip' and sends it directly to the ground; this oc curs at every individual bay. Finally, at the highest point of each 'wing-tip' there is a connection to another extended steel member described as a 'leg'. Each 'leg' supports the outreaching portion of each 'wing-tip' and brings the weight of this memb er downward to meet with the triangular lattice beam. From here, vertical loads are sent down through the foot of each facade column.

The main points where vertical loads are transferred into the ground are at the concrete mass, at the supports which connect to the grounded lift towers, and through the concrete arches which support the facade columns. This forms an even amount of verti cal load-bearing members along the complete area of the main hall. The concrete mass is embedded in the ground at the east, the lift towers conncet at the west, and the concrete arches reach the ground at both the northeast and southwest.

Conclusions

Bibliography

Associated Buildings

Justin Chester and Shane Smith
ARCH 461/561 Spring 1995

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