Construction technology of modern large span space steel structure

Architecture has emerged with the development of human civilization. From the initial shelter from the wind and rain to the later life and production places, the status of architecture in social development is increasing day by day, and it has become an important basic element of human daily activities. In recent years, thanks to the development of building construction technology and the update of material technology, many advanced design concepts have been realized, providing people with a wider indoor space and meeting the needs of human activities for space. Among them, the large span space structure is a building structure formed to meet people’s space needs, which can provide a relatively broad indoor space to meet the needs of stadiums, museums, large exhibition centers and other places.

1 Main types of large span space steel structures

In the field of building construction, the building structure with an indoor space span of more than 30m is called a large span space steel structure, which is a new type of space structure form emerging in recent years. Compared with the traditional building structure, this structural form cancels the support structure inside the building, realizes the overall expansion of space, and meets the needs of modern buildings for large space. According to the different forms of structural support, large span space steel structures can be divided into three forms: space frame structure, reticulated shell structure and suspension cable structure.

1.1 Space frame structure

The space frame structure is connected by many steel pipes and other components according to a specific spatial layout, forming a space frame structure, which can support the roof of the building well and form a huge lower hanging space. This kind of structure has the advantages of strong supporting force, good stability and beautiful form, and is a large span space structure commonly used in building construction. However, the space frame structure needs to be connected by means of articulation or welding. The number of nodes is large, which leads to a long construction period and a high requirement for the quality of the construction personnel. Therefore, the construction is difficult, the efficiency is low, and the cost is high. It becomes the main defect of the space frame structure and affects the practical application of the structure.

1.2 Reticulated shell structure

In simple terms, the reticulated shell structure is a reticulated structure, and the related components of the structure are distributed in a reticulated manner. By applying horizontal pressure and tension to the reticulated shell, the top structure of the building is given stable mechanical support. This kind of structure has the characteristics of both the rod system and the shell system, which can provide a relatively stable support force. It has the characteristics of low dead weight, convenient construction, stability and reliability, and is the most promising large span space steel structure.

1.3 Suspension cable structure

Suspension structures mainly rely on the tension of flexible ropes to achieve structural load-bearing, and their load-bearing performance is mainly affected by the material and performance of the ropes. With the development of material science, various flexible materials and composite materials have come out one after another, which has greatly improved the mechanical properties of ropes, making the suspension structure have higher bearing capacity, and has become one of the important structural forms in the construction industry. Generally speaking, this kind of structure is light in weight, large in span, simple in construction, and material-saving, which is in line with the future development trend of the construction industry, and is widely used in the current engineering fields such as bridges and water conservancy.

2 Basic characteristics of large span space steel structure construction

2.1 High strength and large thickness of material

With the increase of the span, the mechanical action of the structural material increases geometrically, which puts forward higher requirements on the mechanical properties of the material. The current large span space steel structure can no longer meet the minimum span requirement of 30m, and it is developing towards a larger span. In order to ensure the stability and reliability of the structure, it is necessary to carefully select materials, and select materials with higher strength as building components. main material. At the same time, it should be ensured that the material has a certain size and thickness, so as to achieve stable support for the building load.

2.2 The increasingly diverse space frame structure

At present, large span space structure has not satisfied the basic spatial modelling, in meet the demand of floor space at the same time, its structure is becoming more diversified and with the help of bionics, and other forms of inspiration to design a new type of space steel structure constantly emerging, greatly enrich the forms of space structure, realize the diversification of the space frame structure, For people to provide a large number of beautiful shape, reasonable structure of the large span building.

2.3 Design is difficult

Compared with ordinary building structures, large span space frame  structures need to be composed of a large number of rods, and there are an extremely large number of nodes. The entire structure is affected, and reliable mechanical transmission cannot be achieved, resulting in the instability of the entire steel structure, and the harm caused is extremely serious. Therefore, the design of such structures requires repeated calculations and verifications. In recent years, thanks to the development of computer technology, simulation software can be used to realize the simulation verification of structural stability, which greatly improves the efficiency and quality of the design, and plays a certain role in assisting and simplifying the design work.

2.4 The installation accuracy of components is required to be high

Compared with conventional structural forms, large span space steel structures lack the mechanical support in the middle area, and need to use complex structures to achieve effective transmission of mechanics. In the process of mechanical transmission, each component of the structure needs to be reasonably positioned and connected accurately, otherwise the mechanical transmission will be blocked and the structure will be damaged or unbalanced. Therefore, this kind of structure has high requirements on the installation accuracy of the components. It should ensure that the spatial position of the components is accurate and the welding quality meets the standard, so that a reasonable steel structure can be formed as a whole and a stable bearing effect can be exerted.

3. Analysis of construction technology of large-span space steel structure

3.1 High-altitude in-situ unit installation technology

This installation technology belongs to the in-situ installation technology, that is, the components are directly transported to the pre-designed installation position for fixing, and then the components are connected by welding to complete the installation work. This installation method omits the time for lifting and assembling, but puts forward higher requirements for construction. Specifically, first, a stable aerial work platform should be built to meet the installation space requirements; secondly, the components should be reasonably fixed to avoid damage to the installation structure caused by improper fixing; finally, attention should be paid to the efficiency and speed of welding, as far as possible Adopt multi-point construction to improve construction efficiency and form stable structural support as soon as possible.

3.2 Segmented hoisting technology

The so-called segmented hoisting refers to assembling the components in small areas before hoisting to form a relatively independent stable unit, then hoisting the unit and splicing at the pre-designed position to finally form a unified spatial structure. This type of structure can reduce a certain amount of high-altitude installation tasks and reduce the risk of construction peaks. The demand for high-altitude hoisting equipment is relatively large, and it is a common technology for large span space steel structure construction.

3.3 Overall installation technology

The overall installation technology is the limit of the sectional lifting technology. All the components of the structure are assembled on the ground, and then lifted to the design position by high-altitude lifting equipment, fixed, and the entire installation work is completed. This installation technology can greatly reduce the workload of high-altitude installation, and give great safety and quality assurance to the construction. In addition, the entire assembly work is completed on the ground, and the need for temporary fixing points is less, which saves the corresponding fixing workload. According to the different lifting methods of the steel structure, the overall installation technology can be subdivided into three types: the overall lifting installation technology, the overall hoisting installation technology and the jacking installation technology.

(1)The overall improvement of installation technology. This technology is to lift the steel structure assembled on the ground to a suitable height for installation by crane or lifting equipment. It is the most common application in actual construction. The difficulty of construction is to control the height of the lift. In recent years, with the development of mechanical automation technology, the lifting process can achieve effective process control with the help of computer software.

(2)Overall hoisting and installation technology. Different from the lifting and installation technology, the lifting technology is to realize the lifting and lifting of the steel structure with the help of special mechanical equipment.

(3)Jacking installation technology. The main equipment of this installation technology is a jack and an auxiliary support. The steel structure is lifted to a certain height with the help of the jack, and then the temporary support is used for auxiliary support and fixation. After that, the jack is used to lift again, and the above process is repeated until it reaches the design position. In comparison, the application of this installation technology is less.

3.4 High-altitude slip technology

The high-altitude sliding technology is to assemble part of the steel structure in other areas. It is generally divided into assembly by strips or by blocks. After the assembly is completed, the blocks are moved in space with the help of specific slide rails, and they are assembled after reaching the design position. This installation method realizes the separation of the installation area and the splicing area, can avoid mutual interference, and has relatively small requirements on the construction site, so it has relatively many applications in construction. This technology is the development of high-altitude in-situ unit installation technology, which reduces the construction risk of the original technology and improves the safety and reliability of installation.

With the development of society and people’s demand for building space, large span space steel structure will become one of the important structural forms of buildings. The majority of design and construction personnel should actively explore the form and construction technology of large span space steel structures in combination with the actual development of the industry, improve the efficiency and quality of construction, reduce construction risks, and provide the society with high-quality and efficient large span space steel structure building.