Structural expression of terminal buildings at multiple scales(Part2)

Hongqiao T2 Terminal

Hongqiao T2 is a huge project in itself, but its ticketing hall is a small to medium scale space with only 36 meters column network and 12 meters clear height, and the form is also square and plain, the structure adopts a simple system based on common beams and columns to match it. From the perspective of structural expression, it is a large scale, and the structural system is also displayed in a complete way; in view of the accessibility of structural members in the near-human scale space, the design of members and nodes is put in a particularly important position.

The vertical structure adopts the method of transferring horizontal and vertical bearing capacity separately, and the visible range of steel column section is controlled at 450 diameter and 30 aspect ratio, so that the feeling of fine height can be maintained in the space; the horizontal stiffness of columns on the façade side is provided by the slender tension cable support between the columns; the beams are ideally articulated on the end, and the end section is closed down, so as to make it visually lighter; the nodes of the beams and columns, the inter-column supports and the roof supports and their nodes are Specialized design, the delicacy of the structure is perfectly presented through the nodes.

The ceiling is located between the beams and at the end, and closed to the skylight in advance, exposing the lower flange of the main beam and the beam-column node area completely and truly.

Hongqiao T1 Remodeling

The ticketing hall of Hongqiao T1 is a slightly smaller scale building, and the architects wanted the structure to be presented in a delicate way in the architectural space, in harmony with the style of Hongqiao T2. “Delicacy” means that the scale of the components should be small and detailed; a good ‘presentation’ requires that the logic of the structure is clearly visible.

From the stress point of view, this structural system has a wide range of choices. Based on the above requirements and the special constraints as a retrofit structure, the structure adopts three selection strategies: firstly, adopting the integral structural form of roof, façade and canopy, so as to make the bending moments of the large overhanging canopy and the large-span roof cover internally and externally self-balancing, and reduce the bending moments on the original concrete structure; secondly, reducing the bending moments on the original concrete structure through unitization of the main supporting members; and secondly, reducing the bending moments of the rods by unitizing the main supporting members, so as to reduce the bending moments. Secondly, by unitizing the main supporting members to reduce the cross-section demand of the rods, and by designing the rod ends according to articulation to create node performance opportunities; Thirdly, the outer surface adopts continuous box section rods, which is convenient for connection with roof, curtain wall, louver and other skin systems.

Yangzhou-Taizhou Airport

This is the terminal building with no suspended ceiling at all and the main and secondary structures are completely exposed. The main structure of the roof adopts continuous curved beams radially arranged in combination with the characteristics of the fan-shaped plan, with a maximum span of about 45 m. The curved beams are in the form of shaped sections with grooves, so as to visually reduce the height of the beams, which is 1,200 mm at the maximum point; the curved beams are supported by the V-shaped columns, humanoid columns, and swing columns, and provide in-plane lateral stiffness, and the roof’s lateral stiffness in the outward direction of the curved beams is provided by the steel tie rods located in the plane of the curtain wall; the columns and columns are supported by the steel rods located in the plane of the curtain wall. The articulation point of columns and curved beams adopts the form of support, and the articulation between columns and the ground is realized by cast steel nodes; the secondary structure is a single-story hyperbolic quadrilateral diagonal intersecting lattice girder, which is fully compatible with the arrangement of the rhombus-shaped lattice skylight. The main and secondary structures are arranged on top of the common surface, which compresses the occupancy height of the structure and simplifies the structure level of the roofing system, and the whole roof looks compact and simple.

Hohhot New Airport

For the Hohhot New Airport, the architects wanted to interpret the intention of yurt and khata in a modern way in the terminal building. The trusses of the main structure are arranged in a rhombic space frame, which fits the intention of the cross-grid fence of the traditional yurt, and the unfavorable effect of the diagonal main structure span being enlarged is solved by the installation of additional columns, and the lower chords of the trusses are selectively exposed according to the need of displaying the density of the space frame.“Tau Nau” is shown through a higher level of the roof. “The concept of diagonal structure is used in the design of the skylight, the downward umbrella-like diagonal cables penetrating the roof columns suspend the roof structure, the downward diagonal cables themselves have the intention of the Mongolian yurt “Uni”, the diagonal cables are covered with large ETFE air cushions, which reduce the need for the secondary keel of the skylight. The large ETFE air cushion on the diagonal cable reduces the need for the secondary keel of the skylight and realizes the maximum degree of transparency. The importance of the architectural expression of the support columns is emphasized by the focusing of the light from the skylight, so they are made into swing columns articulated up and down to show their delicacy in an extreme way.

The width of the roof overhanging outward is too big compared to the interior span of the trusses, so the Hadar form of the façade is used to provide some support for the overhanging end, and the two ends of the Hadar, which were originally not on the ground, are made to have the function of an arch by installing additional V-shaped flooring columns, so as to share the burden of the overhanging trusses and to reduce the need for their sectional heights.

Mesoscale Expression

Medium scale expression is a selective local exposure of the structure, sometimes combined with expressive architectural form, people can feel the existence of the structure in the space, but generally can not have an intuitive judgment of the whole structural force transmission system. The part of the structure displayed is closely related to the demand of architectural effect, and the light skylight and structural columns are the most chosen parts for expression.

Lukou Airport T2 Terminal

In T2 of Nanjing Lukou Airport, the overall structure of the ticket hall roof adopts a unidirectional multi-tube truss structure with wave-shaped skin on the inner and outer surfaces, and the strip skylight is set in the position of the wave valley, which is a concern in the interior effect. In order to realize the simple and transparent structure of the skylight part and reduce the influence on the effect of skylight, the trusses with main force are arranged along the radial direction to the top of the columns, which reduces the demand of the force of the skylight part structure under the vertical load, and thus it is possible to make it into a single-layer lattice structure. In order to solve the lateral overturning problem of the main trusses supported by single row columns, the transition between single-layer mesh and double-layer trusses is made into a rigid connection, and the positional relationship of the bars in the transition position is carefully planned to ensure the natural and smooth transition of the finalized surface between the skylight and the ceiling; the problem of the in-plane stiffness of the roof structure under the action of the horizontal load is solved by arranging the structural components of the single-layer structure according to the triangular mesh. All the skylight components are fully exposed, and the part of the light single-story structure that seems to be inadvertently exposed will also lead travelers to appreciate the exquisite quality of the entire roof structure, including the one hidden behind the skin.

Wenzhou Airport T2 Terminal

Wenzhou Airport T2 Terminal Building, the roof of the main building adopts the overall positively placed quadrangular cone grid structure, in order to realize the architectural demand of setting up a large area of light skylight in the central axis area, the grid in this area is replaced by the string support structure as a whole, and it is connected with the façade curtain wall structure of the two sides of the air and land as a whole. The chord support structure is supported at the overhanging end of the two-side net frame structure. In order to effectively connect the two sides of trusses into one and improve the integrity of the roof, the chord support structure adopts the space tensile structure made of a number of “cross-shaped tensile beams” continuously composite along the direction of depth, and the upper chord beams are interwoven into the cross-grid structure, which has good in-plane stiffness and provides complete support boundaries for the skylight at the same time. It also provides a complete supporting boundary for the skylight, and the whole skylight shows a sense of order.

Conclusion

Structural expression is a part of the overall expression of the building, which needs to be taken based on the overall design concept, and is not indispensable.At the same time, good structural expression plays an important role in conveying architectural concepts, and even enriching architectural concepts. Therefore, as an architect, we should pay full attention to the possibility of implementing structural expression in every suitable project, especially in large-span projects. As a structural engineer, we should take the initiative to explore various possible ways of structural expression to provide more options for the building, and at the same time, be prepared to put more work into the realization of a good structural expression than in general projects.