The overall installation method or altitude slip method to install steel truss installed altitude assembled, assembled bracket position in the design and erection of the crane to the grid component sub-parts (or block) hanged to the design of the air position bracket assembly. This method is sometimes no large lifting equipment, but the large amount of assembled bracket, aerial work. Strength bolts connecting the steel truss or bolted spherical joints made of steel pipe truss with China steel structure is more appropriate, there are still some of the construction of steel grid method has been applied
Overall installation method is assembled into the ground on the first grid as a whole, and then use the lifting equipment to enhance the overall design position be fixed. This construction method does not need tall assembled bracket, aerial work less easy to ensure the quality of the welding, lifting large lifting equipment, technology is more complex. Therefore, the steel ball node grid (especially the three more rods to the grid and other grid) is more appropriate. Depending on the equipment used, the overall installation method is divided into multi-machine method lift crane, pull the lever to enhance law jack enhance jacking up method.
This method is used for height and weight are not large, the small grid structure. Prior to installation in the ground grid the the dislocation assembly jobs (ie, the assembled position with the mounting axis shifted by a certain distance, to avoid pillars position). Crane (mostly crawler cranes, mobile cranes) assembled good grid as a whole up to the top of the column above, in the shift of the air to fall into place fixed. In order to prevent the grid to enhance the overall collide with pillars the stagger distance depends on the grid to enhance the clear distance between the grid with columns or pillars corbel process, shall not be less than 10 ~ l5cm grid assembly to consider convenience and the air is displaced to facilitate the work of the crane. Required consultation and design unit, part of the edge of the space truss rod pieces left to grid upgrade after welding, or change some of the impact grid to enhance the pillars
After the processing of the metal structure factory, steel truss, single plane truss or three-dimensional truss makes up a small unit transported to the site, site assembly that is in the assembled position of the small unit the truss makes up the entire grid. The grid assembled the key, is to control the size of the axis of the bearing of a good grid framework (pre-amp welding shrinkage amount) and bagging requirements.
Grid welding sphere with steel pipe welding. General strength butt welding, for safety reasons, the increase in the butt at 6 ~ 8mm fillet weld welding. Wall thickness greater than 4mm weldment groove interface should be made. For the uniform and steel pipe butt weld length slightly adjustable, plus casing. The first assembly mounted on the bottom chord afterloading diagonal web members, to be between two truss steel pipe all placed and correction, and then gradually root welded steel pipes such small grid multi-purpose four-crawler up vertical machine ( or car tire crane) lift crane, also with two crawler cranes, or a lever lifting.
If the smaller grid weight, or four cranes lifting capacity to meet the demand should be four cranes arranged in both side of the grid, so as long as four crane slewing the requirements to complete the grid air shift, multi-machine The key is to lift crane a crane China steel structure or some cranes will overload the grid torsion weld cracking. For this reason, before lifting to be measured most crane lifting speed, in order to grasp when lifting. When the grid lift crane to about 30cm higher than the top of the column elevation air shift, move the grid above the top of the column. Grid settled down for the grid produced midline accurately capitals midline agreement prior the grid four corners of each tied to a wire rope, using inverted chain in place on the line
The arrangement of the cable wind rope should enable multi uprooted rod integrally connected with each other, in order to increase the overall stability. The Each uprooted rod at least 6 wind cable rope, the wind cable rope according to the wind load, hoists, pull lever skew, wind cable rope initial stress load, calculated according to the most adverse circumstances combined select. Ground anchors also need to be calculated and determined.
steel pergolas process jingta
http://steelprofileexport.blogspot.com/2012/12/steel-pergolas-process-jingta.html
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