Research on the Synchronization and Closing Control of the New Nanjing Art Museum

The four floors above ground of the new Nanjing Art Museum are a composite tube inclined column steel truss hybrid structure system, with a total steel structure of approximately 15 000 tons. The upper structure is a complex multi-layer irregular circular steel truss structure, consisting of a large-span truss, a cantilever truss, and two circular trusses inside and outside the perimeter. It is divided into two levels: upper and lower, and locally three levels. The truss height is 14. 2 m, and the top elevation is 33. 7 m; the overall size of the outer wheel is 147. 5 m× 103. 3 m, and inner opening size is 102. 8 m × 38. 0 m. The steel truss is supported by 4 cylinders and 10 circular steel tube concrete inclined columns. The construction concept of " in-situ assembly on the ground and overall lifting" is adopted, and the core cylinder and temporary support tower are used as lifting supports to lift the steel truss. In response to the difficult problem of selecting lifting points, the principles of arranging lifting points that are as close as possible to the design state, short force transmission path, uniform structural stress, and small deformation have been determined. Through dynamic simulation analysis of the entire construction process, 29 mixed lifting points have been selected and determined; in response to the difficulty in setting up the lifting support system, a multi-point hybrid support system for the lifting of large and complex irregular trusses has been developed, including lifting reaction frames on the top of the core cylinder column and pre installed trusses, tower supports arranged at the support positions of eight diagonal columns in the south and north zones, and lifting bracket reinforcement and lifting tower reinforcement support systems, meeting the requirements of safety and installation accuracy; in response to the difficulty of hydraulic lifting synchronization for large and complex spatial structures with uneven stiffness, three methods for improving synchronization control were proposed: the minimum sum of squares of displacement deviation at all lifting points, the minimum difference between the minimum and maximum coordinates of lifting points, and the minimum absolute value of maximum deviation. Detailed calculation formulas were derived and successfully applied in the new museum project of Nanjing Art Museum, which achieves precise synchronization improvement under complex conditions; in terms of synchronous control, an automatic measurement system is adopted to enhance synchronous control data. By collecting data through an intelligent measurement robot, the asynchronous situation between each lifting point can be intuitively reflected. At the same time, static level measurement and manual measurement are also used for mutual verification. In response to the challenges of irregular structural plane and elevation, large number of matching points, irregular distribution of point positions, and different spatial angle positioning of matching points, the Bursa model was used to study the general rotation translation matching model with 3 coordinate system rotation parameters and 3 translation parameters as independent parameters. The solution method and analytical solution of the conventional 3D rotation translation matching model were provided. By combining the above methods and corresponding installation control measures, the adjusted alignment points have significantly improved in terms of mean, mean square deviation, and probability distribution, achieving precise alignment.