ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
(1) Super-high structure, large volume of the whole project steel structure weight of 120,000 tons, structural height 450 m, as the saying goes, "one point higher, three points more dangerous", super-high structure to the construction of steel structure brings tremendous risk factors (2) high installation accuracy, influence factors of multi-super-high-rise structure installation accuracy requirements, in addition to measurement, welding and other factors in the construction process affect safety. In addition, with the increase of the height of the structure, it is more difficult to control the deformation of the structure under the action of seasonal temperature difference, diurnal temperature difference and structural temperature difference caused by sunshine. Because of the small vertical deformation difference between the outer steel frame and the concrete core tube caused by different materials, it has a great influence on the force of the outrigger truss. In the construction process, it can not be ignored that (3) the coordination of the project organization is complex, the skirt house is opened in advance to meet the overall construction schedule, the overall stiffness of the internal and external structure, and the permanent knot of the large tower crane. The stress requirement of the structure is that the concrete core tube, the steel frame and the floor concrete should be constructed synchronously with the lifting sequence of the steel structure and keep the proper step distance.
In the process of steel structure construction, civil engineering, equipment installation, curtain wall and other construction units are interpenetrated, and the overall coordination and management of the project is complex. The owner requests the skirt house to open ahead of time. Although the skirt house construction itself is not a construction difficulty, it involves how to make overall plans while the main building is being constructed. It is also a major feature of the project that the skirt house is completed ahead of schedule. 2. The difficulty of the project is (1) the schedule of the steel structure construction is only 18 in order to ensure the smooth realization of the total construction period. In January, the total weight of the steel structure was about 12,000 tons and up to 450 m, involving more than 70 floors. The structure was large in number and heavy in weight, including three truss floors. (2) The site site is narrow and the environmental protection requirements are high, because the project is located in the downtown center, the site is narrow, the maximum distance between the underground diaphragm wall and the subway tunnel is 10 m, the minimum is only 8 m, and the site is mostly office, which puts forward higher importance to the matching management of steel structure construction and the site environmental protection (3) the structure is heavy and the construction is precise. The steel components of high degree engineering are heavy and various in form. How to divide the lifting units reasonably, make full use of the performance of lifting equipment, minimize high bulk and high altitude welding, and improve the installation efficiency?
The three-way truss structure has a large volume, the longest truss is 53m, the heaviest truss is 240t, and the joint form of the extensor truss is fully high-strength bolt connection, which puts forward higher requirements for the installation of steel structure. (4) Due to the superelevation of the structure of the project, how to design reasonable safety operation facilities, including vertical ascent, horizontal passage, operation platform and anti-falling isolation measures, is the premise and basic guarantee of safety construction. Especially in the installation stage of antenna mast, a set of safe, feasible and convenient operation facilities must be designed. While ensuring safety and reliability, safety operation facilities should also take into account the convenience of turnaround and the shelf of correcting welding equipment. Safety operation facilities in ultra-high altitude operation need to improve the psychological state of workers, visual barriers, wind and rain protection and so on. (5) Welding technology requirements are high because this project belongs to super-high-rise steel structure, there are large columns docking with columns. Column-beam butt joint. Steel plate thickness up to 100 mm, material A572, thick plate and other strong butt welding, welding requirements are high, welding work diaphragm is large, welding operation conditions are poor.
It is very important to choose reasonable welding means, process parameters and organization of welding engineering in the welding process, which is related to the construction quality and progress of the structure. The control of structural deformation by reasonable welding sequence should not be neglected.