What is the pre-assembly of steel structure before delivery

The pre assembly of steel structure is the process of temporary removal of large-span columns, beams, derivatives, supports and other steel components and multi-layer steel frame structures, especially the heavy-duty steel structure connected by high-strength bolts, the steel shell structure installed in blocks and supplied in stages.Preassembly is an invalid measure to master the quality and ensure the success of component construction on site.The pre assembly of components shall be based on the type of pre assembled components, with a wide and flat site, large lifting facilities, a working space of more than 12 meters and a workbench.The pre assembled workbench shall be provided with a foundation, the name of the workbench shall be flat and kept on the same level, and the height of the workbench shall be easy to operate.

The worktable beam is a heavy-duty I-beam, and its installation distance shall meet the transverse rigidity requirements of the assembled components.The components shall be assembled freely, and the connecting bolts shall be able to penetrate into the holes smoothly.Preassembly methods include overall preassembly, sectional preassembly and layered preassembly.If the length or size of steel components such as columns, long-span plate beams, analysis frames, roof truss supports, etc. of all pre installed single components exceeds the transportation limit of Railway (or highway), cross-section interface shall be set in the design of installation drawings and connected by riveting or high-strength bolts; or positioning shall be carried out by positioning holes for making analysis frame components, and then transported to the site for operation.Assembly welding.This kind of component is fabricated in sections or single pieces in the factory, and it needs to be preassembled in the factory.

The components are pre assembled in sections and the steel frame is fabricated in sections.The connection of supporting platform beams between columns and between columns needs to be preassembled in sections.That is to say, from the foundation column, every two columns are preassembled units, and preassembly is carried out in order.The shell structure composed of blocks can be preassembled in the assembly site through the sequential operation of 2-4 assembly units.In the process of preassembly, drilling or reaming process requirements are required, which is a redundant measure to ensure the design dimension and tolerance requirements of components, but it will cause the interchangeability loss of connecting holes of Guiyang steel structure components.Therefore, the pre assembly or the whole machine number should be located and the drawing area should be arranged so that the components can be located on site during construction.The working platform for layered prefabrication of multi-layer frame components, including the connection of beams and beams, beams and supports, beams and columns, needs to be prefabricated in the factory.If the size of each section is long and the disassembly space is not ideal, the pre assembly can be operated by imitating the short column method.

After straightening the assembly connection of components, it is necessary to check whether the geometric dimensions of components and connections meet the requirements of installation standards and tolerances.The qualified rate of bolt connection must be 100%.If there is general hole dislocation, the hole should be enlarged.The out of roundness of holes shall not exceed the tolerance requirements.Otherwise, it shall be blocked and re drilled, and the blocking device shall not exceed 20%.