The synchronous lifting scheme of steel strands has significant advantages in the hoisting of super-large components and its feasibility has been verified in numerous practices. The main link of the synchronous lifting of steel strands is to arrange multiple strand jacks at multiple lifting points above the component, and control the synchronous and uniform lifting of each point through the synchronous lifting hydraulic system.
The characteristics of steel box girder hoisting:
1.Steel box girders, as super-large components, have a huge hoisting area and high structural flexibility.
2.The steel box girder is a variable cross-section box girder and the forces at each lifting point are uneven.
3.The overall hoisting of steel box girders requires high precision with an adjacent error of ±10mm.
In view of the above characteristics of the steel box girder, it is necessary to weigh the entire steel box girder before construction. Not only should the total weight be obtained, but also the center of gravity position and the weight of each hoisting point should be found. Only after obtaining the exact parameters can we be confident and reliable in the subsequent construction.
The following is an analysis of the sectional hoisting process of steel box girders:
Longitudinal positioning: The lifting device is pulled into the predetermined position by the transverse strand jack.
Overall lifting: One end of the steel strand is fixed to the lifting node of the steel box girder below. At 4 or 8 o 'clock above, the steel strand lifting hydraulic jack starts the pre-lifting. After the entire steel box girder is under force, it remains stationary for 12 hours to ensure the normal state of the system and then the uniform and synchronous lifting is carried out.
The transverse movement of the steel box girder: After the steel box girder is lifted to the predetermined height, under the transverse traction of four units strand jacks, the trolley for hoisting the girder slowly moves to slide into the air.
Steel box girder positioning: Under the control of the synchronous lifting hydraulic system, the steel box girder is continuously and synchronously lowered to the slide way of the girder body. Through the synchronous lifting hydraulic system, the hydraulic cylinders are controlled to lift the entire steel box girder and place it on the support.
Decomposition of configuration functional components:
First, for the weighing part of the steel box girder, the KIET synchronous weighing hydraulic system is used to obtain the key parameters. The synchronous hoisting hydraulic system controls the synchronous hoisting of the steel box girder. The synchronous lifting hydraulic system controls the overall synchronous lifting and lowering actions of the steel box girder.
The technology of using a synchronous hoisting hydraulic system with steel strands for the overall hoisting of steel box girders is particularly suitable for large-span and large-area hoisting operations. It will play an irreplaceable role in the construction of suspension bridges in the future.
