ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
93 fourth-grade and 32 fifth-grade are decorative poles set up to enrich the shape of buildings. The section and joint form of 2.2 poles are tangent to one or two third-grade poles. All poles in the whole project are made of steel pipes with diameter of D 700 mm. The joint form is intersecting, tangential and occlusive, and the number of multi-pipe intersecting joints is the same. The largest number, about hundreds, is used for the first, second and third level of the cable, that is, the connection nodes between structural members, known as the four or five level decorative cable and the supervisor as the tangent node or pin-through node. Because of the special selection of architectural effect, few joints naturally form occlusion joints. The tangential and occlusive joints are called "secondary joints structure design considers not only dead weight, dead load, overhaul live load, wind and earthquake, but also snow, ice and ice load, as well as temperature, which should be determined by the building to arrange more dense, disorderly intersection of space. This kind of disorder and extreme disorder actually forms the "symmetry" of nature and the "relatively uniform arrangement of nature".
The infinite similarity can be considered that the chaotic limit tends to be uniform. Imagine a bird's nest, with dense poles and basically symmetrical structure, which belongs to a disorderly and slightly orderly braided reticulated shell. However, there is no stability problem of general reticulated shells, and the mechanical deformation performance is acceptable. Based on the conceptual analysis and many years of experience in engineering design, it is concluded that under the technical conditions of structural requirements, such as the composition of joints, the section of trusses and the form of joints, the mechanical properties of structural members under load should be relatively minor, and the safety and reliability can be easily satisfied. The main problem is the construction, and the core problem is the joint fabrication. In the design, we should try our best to improve the technical conditions of processing and installation as far as possible, so as to make it economical and reasonable. On the premise of meeting the basic structural requirements of processing and welding, the thickness of pipe wall should be as thin as possible so as to adopt D700 *10, d700X8 straight seam steel pipe and low-grade steel Q235B for economic calculation. The results of structural stress and deformation analysis [in another paper] validate the conceptual analysis and judgment of the structural designer at the initial stage. 2.4 Joints can be designed by welding joints or cast steel joints. As long as the construction chamfer meets the casting process requirements, the stress analysis of the joints is clear, and the stress of the project is relatively minor. Therefore, the design of cast steel joints is the simplest.
However, the cost of cast steel joints is high, especially for hundreds of joints in this project, there is no duplication. If cast steel is used, it is bound to open the mould one by one. I am afraid that the casting process of each joint must be adapted to the ever-changing bifurcation and chamfering of different parts, and the technical difficulty is not small. As a result, the cost of cast steel joints must be quite expensive and the construction period will be longer. Chapter one upholds the concept of "simplification of complex questions", and regards simple structure of complex buildings and simple processing and installation of complex knots as the highest state of structural design. By using the simplest traditional methods and techniques, all three joints, which are intersecting, tangential and occlusive in geometry, are designed as common welded joints. 2.5 The main joints are intersecting joints. There are hundreds of main joints in the whole project. The architects pursue the smooth intersecting effect of "equal diameter" bars. For example, direct intersecting welding, the chamfer of the intersecting edge of the pipe wall cut by intersecting wire is sharp, which can not guarantee the quality of the weld and the appearance of the weld. The design adopts the technology of equal diameter pipe diameter conversion intersection, skillfully choosing one of the nodes, especially the landing pipe, as the main pipe, keeping the diameter of D700 mm unchanged, and changing the diameter of other parts to D400 mm, and then welding with the main pipe intersection [fig. 4].
After the intersecting welding is completed, the diameter-changing part is wrapped with thin steel plate, and the diameter of the straight-through cable is equal to that of the straight-through cable.