Abstract: The irregular steel structures or steel-concrete composite structures of super high-rise buildings are not only subjected to very complex forces during the structural use stage, but also have particularly complex deformation and stress during the construction process. This project is a steel frame-core tube structure of special architectural form, with many oblique truss structures, whose top is strongly connected with the giant truss or core tube on the opposite side through horizontal members to be a "Mega-structure". There are significant differences in the stress forms of the main components of the steel truss before and after the overall structure synthesis. Therefore, it is considered that the vertical components and corresponding floors should be constructed layer by layer in the conventional sequence, while the diagonal steel truss should be assembled in place first, and the temporary support should be removed after the overall structure is formed, with the gravity load being applied at the same time. Besides, as the vertical stiffness of the core tube and truss varies greatly, the vertical deformation difference between them causes a large internal force on the member connected with the core tube. Because of this, in order to reduce the effect of vertical deformation difference, "release" is adopted in the design, which means the components next to the core tube adopt a method of subsequent fixation and installation to reduce the adverse impact of vertical deformation difference. In order to reduce the initial deformation and internal force of the structure in the process of construction, as well as achieve the above "release" requirements, two construction assembly plans, precise simulation and simplified simulation, were designed and formulated with considering the force requirement and the feasibility and economy of construction, and finite element program SAP2000 was used for calculation and comparison. The precise simulation plan refers to strictly following the construction sequence, fully considering the deformation and stress during the component assembly process, and accumulating them into the final internal force calculation and deformation control. Simplified simulation refers to forming most components in a computation model at once, with a focus on the impact of post installation and post consolidation of some components on the overall structure and related components. The main difference between the two schemes is that Scheme A considers that the newly assembled steel truss will be in a cantilever state for a period of time before the construction is completed, while Scheme B does not consider the impact of this part.
Taking a typical steel truss as an example, this article specifically analyzes and compares the calculation results of the internal forces of the members and node displacements of the two schemes. Due to particularity of the construction plan for this project, the calculation model and parameters are specially processed to achieve accurate simulation of some steps in the construction plan.
The results show that there is no significant difference in the internal force and deformation of the final state between the two simulation schemes, and the deformation modality and internal force distribution are similar. The variance of internal force in the final state of most components is less than 3%. According to the analysis results, the simplified simulation is selected to improve the analysis efficiency on the premise of ensuring the accuracy of calculation.