About Us
2022-12-30
1. Overview of Terminal Engineering
The reconstruction and expansion project of a civil airport mainly includes the new terminal building and the air traffic control building project. A new domestic terminal will be built on the west side of the existing terminal. The new terminal building is 171m long and 48.7m wide, and the terminal building area is about 13860 m². The construction foundation of the terminal building adopts bored cast-in-place piles, the building form is a two-story frame structure above the ground, the roof adopts the form of steel structure with low self-weight, and adopts glass curtain wall. The main building is located in the central area of the central hall, and the boarding bridge connects to the central area of the terminal building. The boarding hall is composed of inner steel pipe columns, outer curtain wall columns and steel pipe space frames. The roof space frame is supported on the top of the column through steel structure nodes, which is a space frame structure system that intersects horizontally and vertically.
2. Construction conditions
The on-site construction environment is very complex, and there are a lot of unfavorable interference factors. The major and difficult points of construction are summarized as follows: First, the construction process is complex, and the steel structure construction can only be carried out after the main structure of the civil construction is perfected. Second, engineering modeling is difficult, there are many integral structural surfaces, and there is no similar construction experience for reference before. The third is high-quality requirements. Fourth, the safety requirements are strict, the site operation height is high, and the wind force is large, which puts forward strict requirements for construction safety management. Fifth, the construction time is tight, and the construction of the steel structure needs to be completed in advance, and the difficulty factor is high. Sixth, the process is complicated. After the main structure is erected, it is necessary to intersperse the steel purlin conversion layer operation, which is difficult in many aspects such as the type of work and the workspace.
3 . Construction difficulties and key points
3.1 It is difficult to guarantee the welding quality of large-area steel structures
Welding efficiency has a direct impact on the progress and quality of the project. Countermeasures: According to the differences in welding methods, according to the characteristics of local temperature, humidity, etc., select the corresponding welding method; adopt the large-area steel structure to be divided into zero to ensure the welding quality.
3.2 It is difficult to control the measurement and release of large-area steel structure assembly
The steel structure, as a curved surface, is erected in situ to ensure the precise connection of the roof.
3.3 Construction progress control is difficult
Countermeasures: formulate corresponding construction procedures. Welding treatment is carried out on the second and third floors, and lifting treatment is carried out by pulling rods. Determine the construction procedures of each sub-district, and carry out construction in a procedural manner.
3.4 It is difficult to tilt the arch truss into place
The section length of the space triangular arch truss is 6.2m, and the maximum segmental mass reaches 57.5t, which puts forward very strict requirements on the performance of the tower crane to a certain extent, because the load bearing pressure is large, and the slings need to be protected.
3.5 It is difficult to close the truss
The span of the main arch in this construction operation reached 179m, which is likely to cause a large deformation of the main arch, making it more difficult to effectively close it in place.
4 Optimal selection of construction plan
4.1 Scheme optimization
Through the optimization of the construction plan, the pulling rods are used for the operation. The corresponding process is: to assemble and position the segmented steel frame. After the docking is completed, the single-angle pulling rod group is used to lift the steel structure as a whole. The use of integral hoisting equipment can effectively reduce the difficulty of vertical transportation, and the work is carried out on the ground and floor as a whole, which can better control the construction safety and progress of the project.
4.2 Selection of hoisting equipment
The terminal roof steel structure constructed in this project adopts a traveling tower crane, and a truck crane is used for auxiliary hoisting. During the hoisting process, the interference caused by the quality of the components should be considered, and the corresponding crane should be determined in combination with factors such as site status, construction price, and construction difficulty. When using a truck crane, it is necessary to measure the ground reaction force. If the truck crane is located on the floor, it is also necessary to measure the bending and shear coefficients of the floor. For those slabs that fail to pass the inspection, reinforcement treatment can be carried out. During the construction of this project, a 250t crane needs to be used to lift the floor slab to install the corresponding steel frame structure. When installing the corresponding steel frame structure on the floor, it is necessary to set corresponding supporting parts on the lower concrete unit to ensure that the reaction force is transmitted to the foundation position. In addition, during the installation process, it is necessary to comprehensively consider the adverse interference caused by the construction such as truck cranes and close-range operations of people and vehicles.
4.3 Construction zoning and installation sequence
The space frame can be divided into five parts in total. Among them, the structure from District 1 to District 5 is basically the same. Among them, except for the third area, which adopts the in-situ splicing on the third floor, the other areas have adopted the overall lifting process of the pulling rod group.
4.4 Layout of pull rods in each zone
According to the construction status of the project, some pull rods are installed in the original outdoor, some pull rods are located on the top of the original steel pipe column, and some pull rods are located on the floor at an elevation of 6.5m.
4.5 Key technologies of steel space frame construction
4.5.1 Overall assembly method and process divisional construction
The process from the inside to the outside is adopted, and the overall improvement is carried out by using the pull rod in a sub-regional manner. In the first to fifth areas, the method of in-situ assembly on the floor is adopted, the middle group of the tire membrane of the surrounding site is welded, and the steel mesh frame adopts the construction process of splicing from the middle to the surrounding area.
4.5.2 Standard area space frame construction
The space frame assembling sequence is: truss A-truss B-truss C-truss D-truss E. After the steel frame structure is assembled, use a truck crane to lift the A truss out of the tire mold and place it on the corresponding concrete floor. Put the two A trusses in their respective design projection positions, and add temporary reinforcement for reinforcement, and lift the trusses in the order of B, C, D, and E from the fetal membrane to complete the entire assembly. When assembling the second floor of the truss, it is necessary to place the measurement stakeout in advance and install the corresponding support points on the second floor slab as support. After the overall assembly is completed, the pull rod is used for the overall lifting process. In the process of lifting the pulling rod, attention should be paid to the scattered splicing treatment with other components.
4.5.3 Space frame construction in three zones
The three-zone space frame construction is mainly composed of three parts: the main single-piece steel pipe and the secondary single-piece steel pipe. On the whole, the three areas are divided into two areas, and the overall lifting treatment is carried out by pulling rods. After completing the construction of the main structure of the steel frame in the tire mold, the corresponding assembly and pairing are carried out on the floor. For the steel frame structure of zone 3-1, the assembly and pairing are carried out on the second-floor slab, and for the member of zone 3-2, the third-floor floor area is processed. After completing the truss splicing in area 3-1, hoist the space frame, and then use the pull rod to perform the corresponding direct processing again, as shown in Figure 1 and Figure 2 below. After completing the splicing of the trusses in Zone 1 and Zone 3-2, the lifting hoist is lifted as a whole, as shown in Figure 3 and Figure 4. When it is lifted to the corresponding position, the surrounding rods of the main structure column are then patched and embedded.
4.5.4 High-altitude connection of steel space frame
After the adjacent areas of the trusses are raised to a certain height, high-altitude docking is required. The docking components are mainly single-piece steel pipe trusses. The installation sequence is still from the inside to the outside, and the two sides are constructed simultaneously. The welded ball joints under the truss are hung with safety baskets.
4.5.5 Steel space frame pairing and splicing measurement control
For the irregular curved surface structure of the roof steel structure, the traditional in-situ assembly method is adopted in the assembly process. When assembling the steel frame in each area, the key control nodes of the primary and secondary components should be placed on the connection points. In the process of assembling it, the projection line should be used as a control standard.
4.5.6 Quality control of space frame splicing and closing
In the process of research and closure, it is necessary to measure the local weather conditions, analyze the “thermobox” effect caused by sunlight, the temperature difference of the structured light surface, and the temperature effect caused by the uneven temperature field distribution caused by the temperature difference of the roof components. Theoretical simulation is preferred. The combined interference temperature is (15 ±7.5) 1 . The coordinates of the spliced structure are tested before the work is closed, and the structure coordinates are processed according to the actual situation of the construction work. Deformation may occur in the process of processing, which should be corrected in time at the construction site. In the process of processing the interface parts, the rod and the ball are in contact with each other, and the lining pipe method is used for construction. For the parts connected with each other with a length of more than 5m, a movable liner is installed to facilitate later disassembly.
4.5.7 Uninstall after splicing is complete
Follow the principle of “deformation coordination, unloading balance, accurate calculation, and strict monitoring” to carry out the unloading processing of the truss, and realize the information management of the unloading process. After the operation and construction is completed, after the construction is carried out by using the winch, the method of cyclic precise control is adopted to unload each part of the steel frame structure in steps to ensure synchronization between the unloading steps.
