Key Techniques for the Complex Connected Structure of the City University of Hong Kong （Dongguan） Library

The main building form of the City University of Hong Kong （Dongguan） Library is only a transportation hub located at both ends， and the main functional floors are hollowed out in the lower part， forming a creative posture of "flying". To achieve the unity of architecture and structure， an innovative floor structure system has been adopted， which includes double core tube support， external cross-story truss connection， and roof secondary truss suspension. Due to the L-shaped floor plan of the connected building and the separation of the two ends of the core tube， the eccentricity between the vertical center of mass and the rigid center of the building is significant， making anti overturning design a key issue； the external cross-story truss forms a folded surface truss to adapt to the facade effect， which generates horizontal forces under vertical forces， increasing the difficulty of cross-story truss design； the internal force design and joint structure of the suspension system for multi-story floors are closely related to the construction and installation plan. Reasonable consideration of the influence of construction sequence can ensure the economic rationality of the system. By analyzing multiple unfavorable overturning load combinations， enveloping the anti overturning capacity， and strengthening the corresponding structures， the overall anti overturning capacity of the building can be improved. The analysis of the force mode of the cross-story truss showed that the cross-story truss connecting the two cylinder bodies was closer to a simply-supported truss rather than a cantilever truss due to its indirect connection with the cylinder body and insufficient connection stiffness. Therefore， the force on the top floor at the plane corner position was complex， and the arrangements of members and joint construction needed to be appropriately strengthened； due to the influence of horizontal forces， the bending area of the cross-story truss facade generated significant bending moments， and the out-of-plane bending resistance of the components and the connection joints with the floor needed to be adaptively adjusted. For the suspended multi-layer floor system，the construction process should be analyzed， and length cutting should be carried out based on the internal force under the gravity load combination of steel tie rods. At the same time， the finite element analysis and joint experiments were carried out on the special connection joints between steel tie rods and floors. The analysis and experimental results showed that the stress performance of this special connection joint could meet the design requirements. The analysis and response methods for structural systems as well as the key and difficult points can provide reference for similar projects.