256HC Mast Section What are the inspection requirements and causes of deformation of tower crane steel structure?
The deformation of tower crane steel structure includes local bending deformation, distortion and eccentricity. According to the deformation inspection requirements of tower crane steel structure, if it exceeds the following range, it is regarded as deformation:
256HC Mast Section：
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1. The straightness tolerance of the member along the longitudinal axis of the whole length is 1 / 750.
2. The deformation of the main chord in use shall not be more than 3 ‰ - 5 ‰.
3. The deformation of web member shall not be more than 2-4mm.
4. The hole distance error of connecting bolt of rod shall not exceed 1 / 2 of assembly clearance, and the roundness error of screw hole shall not exceed 1 / 2 of assembly clearance.
The causes of tower crane steel structure deformation are as follows:
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(1) local bending deformation of steel structure due to collision, knocking and other reasons;
(2) because the connecting bolt is loose, the screw hole is worn into an ellipse, resulting in additional bending moment caused by the eccentricity between the arms and members;
(3) accidental collision and deformation of steel structure caused by misoperation. If the boom is out of control and tilted backward due to the failure of operating mechanism, collision with the tower body will cause serious deformation;
④ the steel structure will be subject to yield deformation (permanent deformation) due to long-term overload.
If the balance of the upper structure is not adjusted during jacking, the center of gravity of the jacking part is not placed on the jacking oil cylinder, so that the top structure is out of balance or even the center of gravity deviates greatly. The guide wheel of the climbing frame has too much pressure on the main chord of the standard section, which causes bending deformation of the main chord of the tower body and instability of the tower crane steel structure, resulting in accidents.
256HC Mast Section：
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