Technical points of steel structure installation

The development of modern science and technology and the comprehensive construction of social economy drive the continuous development of urban high-rise buildings and even super high-rise buildings. Under the support of the current technical conditions, steel structure can be said to be one of the most favored structural modes for high-rise buildings. In the process of building construction, the use of steel space frame structure shows the most prominent advantages, including short construction period, high degree of industrialization, light weight, and high safety and reliability. The above advantages also make the steel space frame installation in all kinds of projects and buildings are used and widely promoted. In order to maximize the reliability and stability of the quality of construction steel structure space frame installation, it is necessary to take targeted installation techniques in combination with the actual situation. This paper is a detailed analysis of this issue.

1 high-altitude bulk installation technology analysis

High altitude bulk method mainly refers to, through the construction site crane equipment, the transportation to the scene of the bulk, as well as transport units for lifting, in the high altitude environment for the assembly of related parts, the formation of the overall structure to complete the installation of the steel structure space frame task. Combined with the practical experience of engineering construction, the installation technology of high-altitude bulk method is mainly applicable to the space frame structure with high-strength bolted nodes or bolted ball parts. Moreover, during the implementation of the whole steel structure space frame installation operation, there is always a part of the space frame to keep the overhanging state in the process of high-altitude assembling. After the relevant parts are spliced together and form a complete structural system, there is no need to set up the bracket parts, which can withstand its own gravity and the pressure exerted by the construction load force. At the same time, it should also be noted that, in order to prevent the whole assembly from being affected by its own gravity, or construction load force and deflection, it is necessary to set up a single pillar on the basis of a certain length of the splicing overhanging part of the overhanging part of the support, in order to ensure that the installation of the safety and reliability of the operation.

At the same time, in the process of setting up the stent, it not only needs to be used as a bearing device for overhead assembly of the space frame structure, but also needs to be used as an operation platform. Therefore, in the process of erection of the relevant bracket structure, its centerline position needs to ensure that it can maintain the corresponding relationship with the nodes of the lower chord of the space frame. After the completion of the overhead assembly operation of the space frame, the bracket needs to be dismantled. In the process of dismantling, it should be noted that: firstly, the order of dismantling needs to be from the center to the outside, dismantling circle by circle; secondly, in the process of dismantling each circle, it is necessary to ensure that the descending speed is balanced, so as to prevent dismantling difficulties arising from the individual bracket’s stress being too concentrated.

2 Aerial slip method installation technology analysis

High-altitude slip method mainly refers to: the space frame strip unit assembly in the building over the horizontal slip, slip process to realize the alignment of the total assembly and installation of the construction technology. Combined with the engineering construction experience, this installation technology program is mainly applicable to the cast-in-place reinforced concrete ring beams and steel space frame support structure for the perimeter load-bearing wall of the project. In the actual installation process, the realization can be based on the ground, or bracket environment, the assembly of the strip unit and the expansion of the operation, in the steel space frame strip unit lifted to a predetermined height on the basis of the application of the pre-installation of the skidding track, in the process of skidding action along the horizontal direction, to achieve the overall space frame for the purpose of the alignment and assembly operations.

Under the support of the technical conditions at the present stage, the rails applied in the process of installing steel structure space frame by overhead skidding method mainly include the following forms: (1) round steel form; (2) flat steel form; (3) angle steel form; (4) channel steel form; (5) steel rail form; (6) I-beam form. Among them, round steel, flat steel, angle steel, and channel steel is mainly applicable to the manufacture of small and medium-sized space frame sliding rail, while steel rail, I-beam, and channel steel can be applied to the production of large-scale space frame sliding rail. At the same time, the fixing of the rail itself and the beam structure can be realized by welding or bolting. Moreover, in order to ensure the safety and reliability of the whole steel structure space frame installation, it is necessary to set up guide wheels inside the rail as a safety packaging device.

3 stripes and blocks method of installation technology analysis

Slitting and block method installation technology is established on the basis of the formation of overhead bulk installation technology. Slitting and blocking method mainly refers to: on the basis of dividing the roof of the building into several units, complete the expansion treatment of the combined unit body strip or block at the ground construction site, and through the application of lifting machinery equipment, hoist it to the predetermined height position along the vertical direction, and complete the assembling operation of the steel structure space frame as a whole under the environment of the high altitude. The advantages of the strip and block method in the installation of steel structure space frame are: on the one hand, it can be adapted to the lifting capacity of the lifting equipment; on the other hand, it can control the workload of high-altitude assembling to a certain extent, so as to ensure the safety and reliability of the assembling operation.

Among them, the strip unit mainly refers to the zones divided along the long span direction of the steel structure grid. The division of each zone is realized as a grid unit. The width of each segment is within 1 to 3 grid cells. At the same time, the length of the strip cell can be the same as the short span of the structural steel grid, or the value is 1/2 of the short span of the structural steel grid, while for the block cell, it mainly refers to the zones divided along the longitudinal and transverse direction of the structural steel grid. Each block is also realized with the network as a division unit. The unit form is mostly rectangular, or regular positive direction. In the process of division, the capacity of the crane at the construction site needs to be fully considered.

In the process of applying the strip-block method for the installation of building steel structure space frame, the horizontal direction of the building roof can be divided and cut along the strip unit assembly. For the completion of the cut block unit, both sides of the majority of independent support devices, the other two sides of the construction site needs to be set up on the temporary top support device to ensure that the support of the steel structure space frame reliable and effective.

 4 Overall lifting method installation technology analysis

The overall lifting method mainly refers to: directly on the ground construction environment to complete the whole steel structure space frame overall assembly operations, assembly is completed after the application of cranes, the whole space frame structure lifting to the design height of the base above, and in the air environment for moving, moving to the development of the position, lowering the lifting arm, and fixed space frame structure. Combined with practical experience, the main advantage of the overall lifting method is: eliminating the need to set up the assembly frame of the operating steps, to a large extent, reduce the operating steps based on the high-altitude environment, and in the ground working environment, for the network structure of the joints related to the quality of welding can be guaranteed. However, because of this installation technology for the lifting capacity of the lifting equipment on site has higher requirements, so it is mostly used in the lifting of the welded ball node mesh structure, as well as three-way mesh structure lifting operations. One point that needs special attention is: considering that after lifting to high altitude, it is more difficult to pull the pole to change the amplitude. Therefore, in order to realize the displacement of the space frame structure in the high altitude, it is necessary to promote the space frame structure to realize the movement of the position through the reasonable application of the horizontal force of the lifting pulley group on both sides of the drawbar.

5 Summary

Under the support of technical conditions at the present stage, the construction process of building steel structure space frame installation is relatively complex, and the quality control of the project is difficult. In order to maximize the safety and reliability of the quality of building steel structure, it is necessary to follow the basic principle of “adapting to local conditions” and make specifications for various adaptive building steel structure space frame installation techniques. During the research and analysis of the installation technology of architectural steel structure space frame in this paper, the following mature installation technologies are mainly elaborated: (1) high-altitude bulk installation method; (2) high-altitude sliding method; (3) strip and block method; (4) overall lifting method. The above types of installation technology in the implementation of the process of operation points are different, need to be treated differently. It is believed that through the full cooperation of all parties, on the basis of the implementation of installation technology, it will be able to maximize the reliability and effectiveness of the installation of architectural steel structure space frame.