1 Project Overview
In the aircraft industry (the new factory building is covered with a three-story square-cone welded ball joint space frame, the plane size of the space frame is 274.0mX140.30m, the span is 140.3m, the central elevation of the main lower chord is 27.50m, and the basic space frame size is 6.0mX6.Om, the thickness of the middle space frame is 7.6~11.4m, the thickness of the space frame at both ends of the door is 9.6~13.6m, the lower chords on both sides of the factory building are supported by double-limb H-shaped steel lattice columns, the column spacing is 12.0m, and the supports are The ball is compared with the support. See Figure 1
Figure 1 the front view of the factory building and the side view of the space frame
2 Roof space structure lifting construction method
The maximum installation elevation of the roof space frame is +39.100m. If it is divided into high-altitude bulk, not only high-altitude assembly, welding workload, on-site mechanical equipment is difficult to meet the lifting requirements, but also the required high-altitude assembly tire frame is difficult to erect, there are many problems. Great safety and quality risks. The construction is difficult, which is not conducive to the safety, quality and construction period control of the on-site installation of the steel structure. If the structure is assembled on the ground directly below the installation position, and the “super-large component hydraulic synchronous lifting technology” is used to lift the whole structure into place, the difficulty of installation and construction will be greatly reduced, and the quality, safety, construction period and construction cost control will be greatly reduced. are beneficial.
2.1 Construction ideas
The steel structure lifting unit is assembled as a whole on the ground directly below its projection surface, and at the same time at the roof structure layer (elevation +27.500m/+25.500m), a lifting platform is set up by using steel columns, lower chord straight web rods of supports and support frames (hanging point), a temporary pipe (lowering point) is installed at the corresponding position of the steel structure hoisting unit and the lifting point, and the upper and lower lifting points are connected by special bottom anchors and special steel strands. Use the hydraulic synchronous lifting system to lift the steel structure lifting unit as a whole by 2m, then suspend the lifting, and install the space frame structure at the door head at both ends of the workshop. The rods, the lifting points of the hydraulic lifting system are unloaded in sequence, and the remaining post-installed rods are installed to complete the installation.
The “integral lifting” of the space frame frame is specifically expressed as follows:
(1) The steel structure lifting unit is assembled into an overall lifting unit on the ground +0.000m directly below the projection surface of its installation position;
(2) Steel columns are used on the roof layer of the main structure, A lifting platform (hanging point) is set up on the bottom chord straight web rod of the support and the support frame, and a total of 28 sets of lifting platforms are set up;
(3) The hydraulic synchronous lifting system equipment is installed, including the hydraulic pump source system, lifter, sensor, etc.; in the lifting unit Install temporary pipes for lifting and lowering points at the positions corresponding to the lifting points; install special bottom anchors and special steel strands between the lifting and lowering points;
(4) Debug the hydraulic synchronous lifting system;
(5) The hydraulic lifting synchronization system adopts the method of grading loading for preloading, that is, according to 20%, 40%, 60%, 70%, 80%, 90%, 95%, and 100% of the design load Load sequentially and step by step until the lifting unit is separated from the assembly platform; measure and adjust the sub-measuring deflection of the space frame at mid-span to meet the requirements;
(6) Fine-tune the elevation of each lifting point of the lifting unit to make it level, and let it stand for 4~12h . Check again whether the steel structure lifting unit and the temporary measures for hydraulic synchronous lifting are abnormal; after confirming that there is no abnormality, start the official lifting;
(7) After lifting the steel structure lifting unit as a whole by 2m, suspend the lifting, and install the doors at both ends of the workshop. space frame structure; lift the steel structure lifting unit as a whole to the installation elevation and suspend the lifting;
(8) Measure the actual size of each point of the lifting unit, check and deal with the design value, reduce the lifting speed, continue to lift the steel structure close to the design position, and lift each point. Through the “fine adjustment and jog” function of the computer system, the lifting points can reach the design position and meet the docking requirements. , The lifting points of the hydraulic lifting system are unloaded in sequence so that the dead weight of the steel structure is transferred to the main structure;
(9) The hydraulic lifting equipment is removed, and the lifting of the steel structure is completed; the remaining post-installed rods are installed to reach the design stage.
2.2 The lifting range of the space frame
The construction scope of the first lifting is 2~24 axes intersecting the A~B axis, and the second lifting construction scope is 1~25 axis intersecting A~B axis. Due to the requirements of structural arrangement and lifting process, except for some pre-installed rods, All rods that interfere with the support between the steel columns need to be installed after the space frame lifting unit is in place. The scope of this upgrade is shown in Figure 2.
FIG.2 space frame lifting
2.3 Space frame lifting process steps
Step 1: Assemble the space frame lifting unit on the ground, use the steel column, the lower chord straight web rod of the support and the support frame to set up the lifting platform, install the temporary pipe for lifting the lower lifting point at the position corresponding to the lifting unit and the lifting point, and install the hydraulic lifting system.
Step 2: Debug the hydraulic lifting system. After confirming that there is no abnormality, carry out a trial lifting. After the trial lifting is no problem, start the official lifting. After lifting the lifting unit as a whole by 2m, the lifting is suspended. Each lifting point needs to be kept within ±20mm during the lifting process. synchronicity.
Step 3: Reinstall the space frame structure at the door head position, and install the temporary pipe for the lifting and lowering point at the position corresponding to the lifting unit and the lifting point.
Step 4: After the structure is formed as a whole, lift the space frame as a whole to the design installation position, and install some post-installed rods.
2.4 Advantages of space frame lifting
(1) The main assembly, welding and painting work of the steel structure is carried out on the ground, and the parts can be hoisted by a truck crane. The construction efficiency is high, and the construction quality is easy to guarantee;
(2) The construction work of the steel structure is concentrated on the ground, which has little impact on the construction of other majors, and can be constructed in parallel with multiple working surfaces, which is conducive to the control of the total construction period of the project;
(3) The auxiliary substructures of the steel structure can be installed on the ground, which can minimize the workload of high-altitude hoisting and shorten the installation and construction period;
(4) The “super-large component hydraulic synchronous lifting construction technology” is used to hoist the aerial steel structure, the technology is mature, there are a lot of successful experience in similar projects for reference, and the safety of the hoisting process is guaranteed;
(5) Through the overall lifting of the steel structure unit, the amount of aerial work is minimized, and the absolute time of the hydraulic lifting operation is short, which can effectively ensure the overall construction period of the aerial steel structure installation;
(6) The hydraulic lifting equipment is small in volume and weight, has strong maneuverability, is convenient for reverse transportation and installation, and is suitable for the use of this project;
(7) The main temporary structures such as lifting and lowering points can be set up by their own structures, and the dynamic load of hydraulic synchronous lifting can be minimized, which can minimize the amount of temporary lifting facilities, which is conducive to the control of construction costs;
(8) Expansion through lifting equipment Combination, the lifting weight, span and area are not limited; the flexible rigging is used to bear the load, as long as there is a reasonable load-bearing lifting point, the lifting height and lifting range are not limited;
(9) The hydraulic lifter anchor has reverse movement self-locking, which makes the lifting process very safe, and the components can be reliably locked for a long time at any position during the lifting process;
(10) The hydraulic lifting system has a millimeter-level fine-tuning function, which can achieve accurate vertical positioning in the air; the equipment is small in size, light in weight, and large in carrying capacity, especially suitable for lifting large-tonnage components in narrow spaces or indoors.