Tensegrity cable dome


Although real tensegrity structure has not been applied in large-scale construction, but the application of tensegrity thought a tensegrity structure - cable dome over the past decade has made great development.

In the decades of 1968 and 1986, D.H.Geiger of the United States completed the design of many membrane structures. On the basis of these projects, geiger used the permanent membrane material of polytetrafluoroethylene to be used for permanent inflatable building, which brought the membrane structure to a new level. In the design of the pneumatic membrane structure construction and use process, geiger other people to notice: although the pneumatic membrane structure with the use of building materials - free air and compressed air has no buckling problems of many advantages, but also has some disadvantages, such as constant blast will cause energy consumption and blower reduced life spans, etc. After reviewed the history of structural technology, geiger's thought of undeveloped but tensegrity structure concept, with huge potential for a flexible structure can do become a certain load under the load of statically determinate structure and can be redistribute through geometric changes in load, so the geiger total in fuller thoughts developed on the basis of tensegrity cable domes, as shown in figure 1-16 and figure 1-17.

Cover, on the analysis of the eight units as shown in figure 1-18 after the cable dome structure, first of all, the new type of cable dome structure is used in the 1988 Olympic Games in Seoul, South Korea gym and fencing hall, the plane of the two buildings are all round. FIG. 1-19 shows the exterior view of the Korean fencing hall.

The domed structure of the cable is mainly composed of the structure element and outer ring beam of the following parts: radial chordate, radial valley cable, oblique line, ring rope and pressure bar, etc. The positions of each component are shown in FIG. 1-16 and FIG. 1-17. For the nodal load of the roof, the transmission method is: the pressure rod - the slanting line + ring to the cable - radial cable (chordate or grain) + pressure bar... Until the compression ring beam. Because not only use the concept of tensegrity cable dome, the vast majority of structural force components of the tension unit, but also processing with proper boundary constraints, thus realize the efficient structure. Tensegrity cable dome is efficient to be able to reflect on the structure design is one of the most obvious characteristics, with the increase of span, the structure of the weight increase is not obvious. The most typical example is the 1996 Atlanta Olympic Games main stadium of the Georgia dome, spanning more than 200 m, with steel quantity is less than 30 kg/m2. The panoramic view of the Georgia dome and interior, respectively, as shown in figure 1-20 and 1-21.

When designing oval of the Georgia dome, American engineers Levi (M.L evy), to cover the cable dome is made of two aspects of change, one is to divide warp/weft frame instead of the triangle, the second is for elliptic plane, in the center of the dome structure set up a tensegrity truss to connect the two end semicircle. Triangular segmentation of cable dome, in geometry, not only closer to fuller original tensegrity model. And it is easier to construct the plane of the ellipse: in the structure force, not only the structure is more redundant, but also the structural stability is better. Cover company's Campbell (Can Bell) and others of warp/weft and triangulation is divided into two kinds of cable dome is found: after triangulation and freedom roof drainage processing advantages of easy and high concentrated load carrying capacity; But the count of dividing rib ring than simple triangular division, construction difficulty and total cost price, and the count of dividing rib ring type cable dome is not sensitive to manufacturing error, show in the design and construction aspects than triangulation has great flexibility.

Cable dome is after the successful application in the Seoul Olympic Games, and successively in the following some international well-known large construction application: red bird (Redbird) at the university of Illinois stadium, elliptic plane 91.4 m x 76.8 m, as shown in figure 1-22 for the construction of the red bird stadium, built after the snow when a panoramic as shown in figure 1-23; The Thunder Dome in st. Petersburg, Florida, with a diameter of 210m in diameter, has a panoramic, nocturnal and interior scene as shown in figures 1-24, figure 1-25 and figure 1-26. The roof of the exhibition field of taoyuan county in Taiwan province (FIG. 1-27, FIG. 1-28) and Japan's tiancheng dome (FIG. 1-29, FIG. 1-30).

Since the study of zhang la's overall structure in the 1990s, the cable dome has been one of the focuses of research and has completed several model tests so far. Figure 1-34 ~ as shown in figure 1 to 37 cable dome experiment carried out in tianjin university of a set of pictures, which is shown in figure 1-31 for cable dome is made of model: 1-1-32, 33 for the test plan of the cable dome structure and section: figure 1-34 adjust the prestressed for test before: figure 1-35 for symmetrical loading process: figure 1-36 for measurement data read: figure 1 to 37 for asymmetric loading process.

Although cable dome structure is not the actual application in large engineering in our country, but the domestic scholars have done a lot of theory research and model test for this type of tensegrity cable dome structure of new type system in the application of the large span building especially Olympic venues laid a good foundation.