Construction Technology of Integral Lifting of Extra Large Heavy Steel Structure Roof

1. The overall lifting construction of large steel structures mainly controls the following three aspects:

(1) Technical control of the large-area assembly of steel roof: the assembly area of the steel structure roof is 20,000 square meters and the tonnage is about 4,500 tons; the assembled trusses include roof structure, support system, roof column purlin structure, maintenance walkway, and other structural forms; Most of the trusses of the roof are super large steel trusses. How to assemble such a large-scale super-large steel truss in place with high precision creates conditions for ensuring overall quality improvement and smooth placement.

(2) Design and calculation control of steel roof overall lifting technology: For the overall lifting of such a large roof system, it is necessary to ensure the project’s safety through reasonable design and calculation.

(3) Computer-controlled hydraulic synchronous lifting technology control: According to the principle of hydraulic synchronous lifting, using lifting equipment, combined with modern construction technology, after assembling thousands of tons of components on the ground, the whole is lifted to the predetermined position and installed in place.

2. Overall lifting design and calculation control of steel roof

For the overall improvement of such a large-span roof system, it is necessary to ensure the safety of the project through reasonable design and verification, so as to provide a theoretical basis for the overall improvement. The force transmission path of the hoisting system is checked and calculated for each part in the force transmission path. The calculation content mainly includes the lifting force calculation, the design of the lifting bracket and the platform beam, the check calculation of the column stability, the design of the lifting anchor, and the check calculation of the working conditions during the lifting process.

(1) Lifting force calculation: establish a finite element calculation model for the entire roof, apply the load that needs to be considered in the lifting state to it, and calculate the support reaction force at the lifting point. The result is the number and specifications of the set jacks basis.

(2) Design of lifting brackets and platform beams: The columns used in this project are steel and concrete composite columns, the lower part is a concrete column, and the upper part is a steel structure column. In view of this structure, in order to enhance the needs, on the basis of the original column height, 3.5m was added as a lifting bracket. According to the lifting process requirements, the lifting platform beam is arranged at the top of the bracket. The platform girder is designed in the form of a box girder.

(3) Steel column stability check: The column used in this project is a steel and concrete composite column, the lower part is a concrete column, and the upper part is a steel structure column. In order to improve the needs, the original column height was increased by 3.5m. Aiming at this kind of relatively special column, combined with the existing steel structure specification, the stability check calculation of the steel column is carried out. The eigenvalue buckling analysis is carried out on the whole column including the steel column and concrete column by using finite element analysis software, and the eigenvalue buckling load is obtained, and the stability of the concrete column and the steel column can be analyzed from the eigenvalue buckling mode.

(4) Design of lifting anchor: The lifting anchor bracket needs to be firmly connected with the lifted roof as support for placing the lifting system anchor. The lifting anchor bracket is welded with steel plates, and high-strength bolts connect the bracket and the lifting lug. The analysis was done using the large finite element program ANSYS.

(5) Check the calculation of working conditions during the lifting process: There is a displacement difference between the lifting points during the overall lifting process. The occurrence of the displacement difference of each lifting point will change the stress state of the structure. The calculation is based on the possible displacement difference. The stress condition of the structure, there are dozens of lifting points, and there are many kinds of load combinations. It is necessary to select the more dangerous situations, carry out the combination of lifting displacement difference conditions, and check the internal force changes of the roof system during the lifting process. Ensure the safety and reliability of the lifting process.

3. Computer-controlled hydraulic synchronous lifting technology control

The overall lifting of large-scale steel structures with large spans is difficult in both position control and load control. The computer-controlled hydraulic synchronous lifting technology provides a guarantee for the safe construction of the roof steel structure. The overall lifting technology mainly controls the following aspects.

(1) Overall promotion process

(2) System composition: The computer-controlled hydraulic synchronous hoisting system consists of steel strands and hoisting cylinder clusters, hydraulic pump stations, sensor detection, and computer control (control components).

(3) Arrangement of lifting cylinders and other lifting equipment: After the lifting points are determined, the lifting force of each lifting point is determined, and this is the basis for determining the type and quantity of lifting cylinders. At the same time, other lifting equipment is arranged according to the lifting plan.

(4) Synchronous control of the position of the hoisting point: the height difference between the hoisting point and the main hoisting point is measured by the control system at any time, and the information is fed back to the control system of the hoisting point in time. By adjusting the hoisting system, It can reduce the height difference between the master and slave lifting points and realize the overall lifting synchronization.

(5) Overall lifting safety control: In the overall lifting construction, safety measures are particularly important, and four major safety measures should be controlled: safety measures for the lifting structure system; mechanical safety for lifting cylinder; safety for the hydraulic system; safety for the computer control system.