(1) Overview of On-Site Installation Plan
The steel structure of this project is in the form of a frame. Based on the component type, weight, installation position, actual site conditions, and the lifting capacity parameters of the tower crane provided on site, a comprehensive installation method is adopted for the steel structure of this project.
1. On-Site Installation Method for Steel Structure:
The frame columns, beams, and other components are relatively light in weight. The NK250 25t truck crane will be primarily used for hoisting and positioning.
2. On-Site Installation Sequence for Steel Structure:
The hoisting of the steel structure follows the principle of "starting from the middle, then to the outer sides; columns before beams; lower components before upper components." A stable frame system is first established in the central part of the factory building. Then, the remaining steel columns and beams are installed symmetrically, advancing toward both ends. The sequence is shown in the figure below.
Single Factory Building Erection Sequence (Center-to-Ends Method)
(2) Analysis of Main Installation Components
The main components of this project include steel columns, steel beams, purlins, diagonal braces, etc. The steel material is Q345B.
1. Selection of Cranes
According to the site layout plan, a total of five steel structure factory buildings require installation. Based on the analysis of their lifting performance and working conditions, four NK250 25t truck cranes will be provided on site.
(4) Steel Structure Installation Process
1. Overall Installation Process (taking the freezer warehouse as an example):
Anchor bolt re-inspection → Unloading of steel components → Component incoming inspection → Direct hoisting and positioning by truck crane → Temporary tightening of anchor bolts → Temporary bracing and stabilization with guy cables → Adjustment of steel column axis position and verticality → Tightening and welding of steel column bolts and base plate clamps → Installation of the next steel column → Installation of braces between steel columns → Formation of the first stable lattice system → Ground assembly of the steel roof truss into a complete unit and dual-crane lifting into position to form the first steel roof truss → Symmetrical installation of columns and roof truss systems on both sides → ... and so on → Installation completed, structural acceptance.
2. Division of Steel Structure Installation Zones
This project consists of five sections: meat freezer, meat market, vegetable storage, vegetable market, and open sales area. According to the construction flow division, they are divided into five zones. The specific zoning is shown in the figure below.
3. Overall Steel Structure Installation Sequence
According to the overall project plan, two construction teams will work simultaneously. The overall installation sequence for the five zones is: Zone 1, Zone 2, ... Zone 5. For the same factory building, the steel component installation sequence adopts the method of "error reduction, from the middle to both ends."
4. Steel Structure Installation Sequence (taking the freezer warehouse as an example):
(1) Install the first row of steel columns.
(2) Install the second row of steel columns.
(3) Install the connecting beams (or tie bars) between the steel columns.
(4) Install the first steel roof truss using dual-crane lifting.
(5) Install the second steel roof truss using dual-crane lifting.
(6) Install the purlins between the two roof trusses to form a stable frame system.
(7) Continue installing the steel columns, connecting beams, roof trusses, and purlins of the next rigid frame.
(8) Continue installing the roof trusses sequentially according to the above procedure, while the bracing between columns is also installed in an interspersed manner.
(9) Continue with the installation.
(10) Completion of roof truss installation.
