Analysis on the installation technology of steel structure space frame ——Taking a city steel structure construction project as an example

Especially in the construction of steel structures in large-span construction projects, it is necessary to adopt scientific construction methods to ensure the construction of steel structures. went well. The steel space frame installation technology is a widely used construction technology in the current large-span building steel structure construction. Strengthening the research on the steel space frame installation technology for steel structures has also become an inevitable way to promote the development of my country’s construction engineering construction industry.

1 Common forms, characteristics, and construction methods of steel structure space frame installation in domestic and abroad

As the main method of steel structure construction in the current large-span construction projects, the installation and construction of steel space frames occupy an important position in the development of the construction engineering industry in the new era. In recent years, large-span construction engineering structures have gradually become the most rapidly developing type of construction project, and the installation and construction of steel space frames for steel structures have become an important link in the construction of building steel structures. Due to its advantages of being lightweight, material saving, high installation and construction efficiency, and construction safety, steel space frame frames have been highly concerned and recognized by people in the industry. Based on this, the research on steel space frames at home and abroad has also become more and more in-depth, and the forms of steel space frames have been studied and summarized: From the perspective of the composition of layers of steel space frames, the forms of steel space frames can be divided into Double-layer and three-layer space frames; from the perspective of support, plate-like space frames with different supports can be divided into single-span and multi-span; from a structural point of view,  plate-like space frames are further divided into cross truss systems and space truss systems. Therefore, the current forms of steel space frames are mainly divided into three categories: plane truss space frames, quadrangular pyramid space frames, and triangular pyramid space frames.

In the spatial structure construction of large-span construction projects, the characteristics of the steel space frame structure are mainly manifested in the following five aspects: First, compared with other spatial structure systems, the steel space frame structure is more convenient in the construction of the spatial structure. It is suitable for the construction of large-span, large-column mesh roofs and other structural forms. Second, the overall weight of the steel space frame structure is lighter and the economy is higher. In the actual construction process, compared with the flat steel roof truss structure, when the building span is less than 30m, the steel consumption of the steel space frame structure can be reduced by 5% to 10%, and when the span exceeds 30m, the steel consumption can be reduced by 10% to 20%. Third, the steel space frame structure has a small self-weight and superior seismic performance, which can comprehensively improve the safety of span construction projects. Fourth, the installation and construction are simple, the types of rods and nodes are fewer, the overall structure size is small, and the transportation, storage, loading, and unloading are more convenient. Fifth, the plane layout is flat, which is beneficial to the installation and construction of the ceiling and pipelines of the subsequent buildings.

In the installation and construction of large-span steel structure steel space frame, the common construction methods mainly include a high-altitude bulk method, high-altitude sliding method, integral pre-lifting method, and mobile support installation method. The construction process of the high-altitude bulk method includes three steps: erecting the supporting frame, installing the space frame structure, and removing the supporting frame. Large-scale machinery and equipment are not required during the installation and construction process. It is a traditional steel space frame installation and construction technology. In the actual installation process of the high-altitude sliding method, the pre-set sliding rails are used to slide and assemble the support bars of the steel space frame. The difficulty of this method lies in the design and laying of the sliding track, and the stiffness, bearing capacity, and stability of the sliding track are difficult to control. The overall pre-lifting method is to assemble the steel space frame unit on the ground, and then use a hoisting machine to hoist the assembled steel space frame to a predetermined position for adjustment and fixing by horizontal or vertical hoisting. At present, in the installation and construction of steel space frames in large-span construction projects in China, the overall pre-lifting method is a widely used installation method, which has the advantages of high construction efficiency, high assembly quality, no need for turnover materials, and construction cost savings. However, due to the limitation of the specifications of the hoisting machinery and equipment, in the application of the overall pre-lifting method of the steel mesh frame, the construction site needs to be carefully selected, and the overall weight of the steel mesh frame should be within a controllable range. The mobile bracket installation method is to install the steel space frame structure on the movable support frame, and then remove the temporary support after the steel space frame is completed. Compared with the first three methods, the steel space frame mobile bracket installation method has less use of supporting scaffolds in practical applications, lower labor cost investment, and higher construction efficiency. However, in the actual installation process, it is necessary to ensure the smoothness of the sliding track to avoid affecting the stability of the overall construction. In the actual installation and construction of steel structure steel space frames in large-span construction projects, it is necessary to scientifically determine the specific method of installation and construction of steel space frames according to the overall situation of the project space structure and actual construction conditions. It is possible to improve the construction efficiency and reduce the construction cost investment, which is of great significance for the installation and construction of the space support structure of the large-span construction project.

2 Project overview and specific construction

2.1 Project Overview

The main body of the project is the domestic waste incineration power generation sludge co-processing project, which belongs to the second phase of the project. The main construction location of the steel structure project in project is inside the main workshop, above the loading ramp, and the fly ash temporary storage room. The overall consumption of steel in the installation and construction of the steel frame mesh of the project’s steel structure is 3,000 t, and the total area of the project’s roof steel structure is as high as 22,400 m2. In the project, the installation positions of steel frame nets are mainly distributed in functional workshop areas such as flue gas, incineration, garbage bins, unloading platforms, and sludge drying treatment, with a total construction area of more than 17 500 m2.

2.2 Specific construction

(1) Selection of construction methods. According to the main construction methods of the steel structure steel space frame mentioned in the above article, although the high-pass bulk method can effectively reduce the construction cost in this project, it cannot guarantee the construction period, and the overall engineering volume is large, and the installation and construction of high-altitude operations Quality cannot be guaranteed. Although the slip method has high construction efficiency and can guarantee construction quality, there are too many construction links and it is easy to increase the overall construction cost of the project. Therefore, after analysis and research, the steel structure steel space frame installation and construction of this project adopt the joint installation construction method, and the high-altitude bulk method and the high-altitude sliding method can not only reduce the construction cost, improve the construction efficiency, but also ensure the installation and construction of the steel space frame. The overall mass quality and construction safety meet the specific requirements of the project construction.

(2) The construction sequence is determined. In the installation and construction of steel structure steel space frame of large-span construction engineering, the determination of construction sequence is of great significance. It is necessary to comprehensively consider the actual situation of the project and the actual needs of the builder, so as to comprehensively improve the overall efficiency of installation and construction and reduce construction costs. In this project, the project department finally determined the construction sequence as follows according to the actual situation of the installation and construction of the steel space frame of the engineering steel structure and the environmental conditions of the construction site, as well as the actual requirements of the construction party for the construction period: steel space frame of garbage warehouse → incineration room Steel space frame → steel space frame in discharge hall → steel space frame in sludge drying room → steel space frame in flue gas room 1 → steel space frame in flue gas room 2.

(3) Analysis of hoisting ideas. In the actual process of installation and construction of the steel structure steel space frame of this project, according to the actual situation of the project site: the length of the steel space frame at the location of the garbage bin exceeds 90 m, the span exceeds 38 m, and the overall construction area exceeds 3 500 m2. The construction is affected by site restrictions, and ground assembly cannot be carried out. The installation and construction of the steel space frame at the unloading hall have a span of 28.2 m, a length of 98 m, and an installation construction area of 2763 m2. The functional structure in this area has a low foot, and the elevation of the steel space frame is only 20 m. The installation length of the steel space frame at the location of the sludge drying treatment workshop is 60.5 m and the span is as long as 17 m. The total construction area is 1028 m2, the span is small and the elevation is low. Therefore, the installation of the steel space frame in the three functional areas of the garbage bin, the unloading hall, and the sludge drying treatment workshop in this project needs to be installed by hoisting.

(4) Selection of hoisting equipment. In the selection of hoisting equipment for this project, there are certain differences according to different construction positions, construction conditions, installation methods, and selection of hoisting machinery and equipment. The details are as follows:

①In the installation and construction of the steel space frame in the position of the flue gas room, the installation method is as follows: Setting up the starting frame → accumulating slip → high-altitude bulk loading, the selected hoisting machinery, and equipment including 50t and 70t truck cranes.

②In the installation and construction of the steel space frame in the incineration room, the installation method is to set up the starting frame → cumulative slip, and the selected hoisting mechanical equipment includes a 200t truck crane and TC7015 tower crane. 

③In the installation and construction of the steel space frame at the location of the garbage bin, the installation method is to set up the starting frame → cumulative slip, and the selected hoisting machinery and equipment include a 200t truck crane and TC7015 tower crane.

④ During the installation and construction of the steel space frame at the location of the unloading hall, the installation method is to set up the starting frame → high-altitude bulk. The selected hoisting machinery and equipment include 25t truck cranes and TC7015 tower cranes.

⑤In the installation and construction of the steel space frame at the location of the sludge drying treatment workshop, the installation method is high-altitude segmented bulk, and the selected hoisting mechanical equipment is a TC7015 tower crane.