Optimization Analysis of Lifting Scheme for Multilayer Connected Structure with Discontinuous Bottom Floor

With the development of steel structures in buildings, high-rise building clusters have sprung up like mushrooms after a rain, and setting up steel connections between two high-rise buildings is a common structural form. At present, for the installation of conventional high-altitude connected structures, the installation method mostly uses ground assembly and overall lifting to the design position. However, for multi-layer connected structures with discontinuous bottom layers, on the one hand, the ground assembly jig frame is high, which leads to high-altitude operations, which is not economical and not safe; on the other hand, the bottom structure needs to be reinforced during assembly, which is cumbersome to construct. Therefore, how to develop a more economical, safe, and fast construction method is a consideration for construction plan developers. The article takes the Hangzhou Yunmen project as an example and provides two construction plans: cumulative lifting and layered lifting. The two are compared in terms of structural deformation, construction economy, safety, and timeliness. In terms of stress, using the above two schemes for construction, for the tower, the difference in the maximum stress value of the member is small, but the additional stress of the construction component using layered lifting is smaller, making the stress more reasonable; for connected bodies, the maximum stress values of the members are basically the same, but the overall stress of the members using layered lifting is relatively small; for the lifting reinforcement rod, the maximum axial force of the reinforcement rod using the layered lifting scheme is 10 905. 27 kN, while the maximum axial force of the reinforcement rod using the cumulative lifting scheme is 12 615. 81 kN, which is reduced by about 13. 6% compared to the latter. Therefore, using the layered lifting scheme can reduce the demand for its cross-section and facilitate removal after the lifting is completed. In terms of deformation, using the above two schemes for construction, the maximum vertical deformation of the structure is located in the middle of the connected span, and the difference in deformation values is not significant; while the maximum horizontal deformation of the structure is located at the top layer of the tower, there are some differences in deformation values. The deformation value of layered lifting is relatively small, which is due to the use of layered lifting. Before the secondary lifting, the upper structure of the connecting body and the tower have already been integrated, with a certain level of horizontal stiffness. In terms of construction, when the cumulative lifting scheme is adopted, the lower structure is installed at low altitude, the upper connected structure has a longer suspension time and poor timeliness, and the connected structure does not form an effective connection with the tower, resulting in poor construction safety; while by adopting a layered lifting scheme, the upper connected structure is directly reinforced after being lifted in place, forming an effective connection between the connected structure and the tower. At that time, the assembly work of the lower triangular area structure can be carried out simultaneously, with better timeliness and safety. In terms of economy, there is a small difference between the two, and hierarchical upgrading has a high demand for increasing the number of equipment. The results indicate that for the construction of multi-layer connected structures with discontinuous bottom layers, the layered lifting method performs better in terms of structural stress and deformation, construction economy, safety, and timeliness.