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2023-07-175、Internal prestressing construction technology of long-span steel truss
High-altitude prestressing construction of the hangar gate truss: 55 Φ15.2 galvanized unbonded steel strands (tensile strength 1860MPa) are arranged in the middle length (137m) of the lower chord steel pipe of the gate truss as post-tensioned prestressing tendons. Because the gate truss and the roof space frame are lifted at the same time, and the internal force of the rods during the lifting process is different from that in the use stage, the prestressed tension construction of the gate truss must be carried out at high altitude after the gate truss and space frame roof are lifted. The steel truss at the gate head of this project has a large span and a heavy load. Prestressed steel cables are used in the steel truss body. Reduce costs by using custom anchors to speed up the construction of wire rope beams.A protective casing is set in the lower string tube to reduce the wear of the steel strand. Before construction, the large-scale general-purpose finite element analysis program ANSYS is used to model the entire project and all nodes in detail, and finite element analysis is performed on key nodes to ensure the safety of the nodes’ stress, and to optimize the structure and shape of the nodes. After the steel space frame is lifted in place, the steel strands will be threaded after the post-installed rods are installed; the 55 steel strands will be bundled with a special anchor head, and the wire rope will be pulled by a hoist for one threading; the pipeline robot will be used to Traction wire harness. Set up a temporary steel platform on the top of the column for threading, tensioning, and grouting to ensure construction safety; two 400t jacks are used for tensioning at both ends, and one structure is tensioned each time.
6、Large-span roof space frame overall lifting structure safety monitoring construction technology
The hangar roof space frame structure of this project is a large-scale welded ball space frame structure, which is assembled in-situ on the ground in bulk during construction, and the space frame structure needs to be arched according to the design requirements (maximum arching 300mm) during the assembly stage, resulting in all welded balls At the same time, after the overall lifting of the space frame is in place, there are still 212 rods that need to be installed afterward. At this time, the structure is still in a relatively unstable and flexible hanging state. The stress and strain monitoring technology is adopted in the overall lifting process of the network frame, the prestressed tension construction process, and the independent column construction process of the project. During the lifting process, the key monitoring content is the change of the height of the hanging point, the deformation of the space frame structure, the deformation of the original structural column, and the deformation of the temporary lifting tire frame. For the hanging point and the deformation of the space frame structure, the steel ruler hanging upside down method and the measuring instrument are used to monitor. Other deformations and the main members and key parts of the space frame are monitored by posting strain gauges. For the cable force, stress and deformation monitoring during the construction process, reliable monitoring methods are adopted to monitor the deformation of the steel structure and the force of the prestressed steel cable in real time to ensure the safety of the structure construction and ensure that the forming state of the structure is consistent with the original design .
7、Synchronous installation technology of super-large-diameter spiral air duct for overall lifting of steel structure space frame
Ventilation duct construction of spray-painted hangar: There are more than 1,000 m-long air ducts arranged on the upper and lower chords of the hangar hall space frame, and the air ducts with a diameter greater than Ф1.8m are about 400 m long. In the middle of the upper and lower strings of the space frame, it is almost impossible to install such a large-sized air duct after the space frame is assembled. According to the installation height of the air duct, channel steel is used to make a height-adjustable independent air duct bracket, which is welded on the corresponding welding ball, and a diagonal brace is installed between the two brackets to ensure the stability of the bracket. According to the diameter of the air duct, an arc bracket of a corresponding diameter is provided on the bracket. The steel structure space frame and the super-large-diameter spiral air duct are installed synchronously, and finally they are lifted as a whole.
8、Prefabricated construction technology of suspended dock and hangar door
There is a suspended mobile maintenance platform in the paint spraying warehouse of this project, which can carry out all-round maintenance on various areas of the aircraft tail, which greatly improves the maintenance efficiency of the aircraft. The suspended mobile maintenance platform is also called aircraft maintenance dock. Four aircraft maintenance docks are designed in the G3 hangar, which are two 18m long tail docks and two 37m long fuselage docks. The docks are hung on the lower string node of the space frame through guide rails. The weight of a single fuselage dock exceeds 45t and a height of nearly 20m. The components of the aircraft maintenance dock are all connected by bolts during the design of the processing drawings. Under the condition of long-distance transportation, there is no need for secondary welding in the assembly process; the processing accuracy is strictly controlled and the components are completed in the factory according to the drawings; before sending to the project site, a series of strict screening is required to conduct quality inspections on the main components of the dock , The main structure needs to be inspected and pre-assembled; in the on-site construction, the machine dock does not damage the anti-corrosion layer, and all components only need to be assembled according to the normal process. Each single machine dock is assembled on the ground and then hoisted on the pre-installed On the track, the assembly and construction efficiency is high, which greatly saves the on-site construction period. The hangar door is a steel structure track door, with a total of 8 doors, each with a size of 22m in height and 19m in width. It is also processed in the factory with a fabricated steel structure. The site only needs to be assembled into pieces according to the drawings and then hoisted one by one.
9、Ultra-high-altitude fire-fighting pipeline installation and construction technology as a whole with the space frame
The super-high-altitude fire-fighting pipeline is installed and installed with the overall lifting of the space frame. The construction technology is to install the fire-fighting pipeline before the steel structure space frame is lifted, which avoids the risk of super-high-altitude operations. The flow construction of “the assembly of the lower string of the space frame – the installation and connection of the fire pipes – the assembly of the upper string of the space frame” and the reduction of high-altitude operations can greatly reduce the input of manpower and material resources, reduce the waste of materials, and greatly reduce the rework rate. Social and environmental resources have a certain significance; at the same time, the use of this technology can speed up the construction progress and save construction costs.
Improve the manufacturing precision and installation accuracy of fire-fighting pipelines, and reduce the assembly stress generated during the installation of fire-fighting pipelines. The installation of fire-fighting pipelines is carried out together with the installation of the space frame, forming a flow construction of “first complete the assembly of the lower strings of the space frame, then install the fire-fighting pipelines, and then assemble the upper strings of the space frame”, which solves the problem of the difficulty of interspersed installation of fire-fighting pipes in the space frame, and In the flowing water construction, the fire-fighting pipeline is intersected with the air duct and hydropower construction, which is convenient for pipeline adjustment and maintenance. When the fire-fighting pipes are connected by clamps, the tightening torque of the bolts is adjusted to 85% of the design requirements to increase the deformable margin of the fire-fighting pipes when the space frame is lifted as a whole. After the lifting is completed, the fire-fighting pipeline shall be refitted and tightened to the design requirements. According to the layout height and quantity of fire-fighting pipelines, add corresponding anti-seismic supports for fire-fighting pipelines to ensure the stability and safety of fire-fighting pipelines during the overall lifting process. Setting stress monitoring points for fire-fighting pipelines not only monitors whether the stress of the fire-fighting pipelines is reasonable during the overall lifting process, but also determines the stress-concentrated parts of the fire-fighting pipelines during the lifting process, and carries out key maintenance after the lifting is completed. The computer-controlled hydraulic synchronous lifting technology is used to control the movement posture and stress distribution of components to ensure the stability and safety of the lifting process. After the overall lifting and in-place unloading of the space frame are completed, the fire-fighting pipelines shall be reinstalled, overhauled and pressure tested.
