First of all, in order to effectively arrange the construction technology of the entire steel space frame, the space frame structures involved in this article are assembled on the ground as a whole, and then the rod-pulling equipment is installed. After the structure is properly upgraded and in place, the relevant civil engineering technicians can carry out a series of basic construction, such as debugging equipment and construction of the surrounding floor environment. In this way, it is possible to ensure that the various components of the plant construction can achieve effective cross-construction, thereby shortening the construction period. Secondly, in order to effectively prevent the impact of external environmental factors and time processes on the quality of the steel space frame structure, it is necessary to carry out certain welding, painting, etc. after assembling, but often in the process of construction of some large-scale workshops Due to the large-scale and large-scale structure of the frame structure, this process will also have a certain impact on the construction period. Therefore, the assembly and painting of the steel mesh frame must be carried out on the ground to ensure its construction quality and safety. In addition, in order to effectively stabilize the steel space frame structure, a large number of auxiliary components need to be optimized. In order to ensure the overall construction quality, all the auxiliary components are assembled on the ground, which can minimize the workload of high-altitude hoisting. Finally, it is necessary to effectively reduce the hoisting construction during the overall construction of the steel space frame. On the one hand, hoisting construction is more dangerous than ground construction, and on the other hand, construction efficiency will also be significantly reduced.
2.1 Composition of steel space frame construction system
On the basis of the relevant empirical research, this paper proposes the overall construction system of the steel space frame in this research, and its main components include lifting and pulling rods, electric hoists, integrated control boxes, and integrated displays. At the same time, in order to further ensure the safety of personnel during the construction process, the selected electric hoists are equipped with self-shrinking devices to prevent sliding chains, and integrated control lines and control boxes are connected to these electric hoists to ensure their electric hoists. excellent braking and high efficiency during lifting. The working process of the electric hoist is to hang one end of the electric hoist on the lattice lifting frame, and the other end is tied to the ball node of the space frame to be lifted through high-quality wire ropes. object lift
2.2 Design of lifting and pulling rods
In the preparation stage of the overall construction of the steel space frame structure, after a series of studies on the construction environment and plant usage, a series of construction plans are formulated, including the design of the hanging point diagram. Therefore, in the process of design and construction of the lifting rods, the construction should be carried out in strict accordance with the specified position and quantity in the lifting point diagram. There are 4 lifting and inverted chains, and the lifting capacity of each electric inverted chain can reach as much as 10t. The electric inverted chain and the space frame structure are connected and fixed by a wire rope with a diameter of about 25mm. One end of the wire rope is connected to the string ball on the space frame. The nodes are effectively bundled and locked with a snap ring, while the other end is fixed on the hook of the inverted chain.
2.3 The dislocation assembly of the supports
In order to effectively reduce the time for specific operations in the air, the dislocation assembly process method is adopted in the process of assembling the space frame on the ground, so as to ensure that the steel space frame is raised to the design standard height as soon as possible. To achieve in-place fixation. Specific operation: When assembling on the ground, shift the position of the support to the right by 700mm, wait until the space frame is raised to the standard height and then shift it to the left by 700mm, and finally let it fall on the relevant position of the column top design.
3.1 Construction technology
After a strict analysis and demonstration of the specific requirements and construction environment of the steel space frame workshop in this study, the specific construction technology of this paper is summarized. The specific process: material preparation – quality inspection – space frame assembly – welding, painting – lifting frame design – the first overall lifting 300mm – the second overall lifting 1200mm – the third overall lifting to 10m from the ground – the fourth overall lifting Lifting to 15m from the ground – overall translation of the space frame structure – installation of the space frame in place – deflection detection – acceptance stage.
3.2 Specific operation points
(1) The first lift. To put it simply, the first upgrade of the space frame structure is mainly to detect whether all auxiliary structures of the overall construction have been installed in place, whether the installation meets the design requirements, and to observe whether some steps occur during the actual construction process. Change. For example, it is necessary to test the foundation of the pulling rod. The quality and safety of the pulling rod will directly affect the effectiveness of the overall construction; in the process of the initial lifting, whether the force of the reverse chain used for lifting is uniform, and its electric reverse chain And whether the wire rope used for tying can be suitable for the current construction work.
(2) Second boost. Through the previous test lifting link, after ensuring that the system is free of errors, the lifting process can be carried out at a higher height, but the height of the lifting is still not too high, but within a controllable range, so as to ensure that the Effective maintenance is carried out after a system failure is detected. Because the reverse chain has been lengthened, the top displacement monitoring team of the lifting frame records the initial position of the displacement indicator bar at the top of the frame, and the difference cannot be greater than 25mm in each subsequent lifting process.
(3) The third and fourth promotions. The third lift always keeps the horizontal projection position of the space frame unchanged, and the hoist on the top of the lifting frame evenly lifts the space frame to a position 10m above the ground (the most unsafe position). During this lifting process, the tension of each hoist cable is kept at about 60kN. In order to keep the horizontal projection position of the space frame unchanged, it is necessary to apply increasing horizontal force to the space frame. After that, continue to slowly apply and adjust the horizontal pulling force to the right, keep the horizontal projection position of the space frame unchanged, and continue to lift the space frame to the top of the column 15m above the ground.
(4) The space frame is in place. After the space frame is lifted to the design elevation of 15m, the space frame support node is moved to the installation position on the top of the steel column by tightening the horizontal chain hoist until the space frame support node is directly above the steel column, and then falls to the top of the column synchronously. at the installation location.