The super high-rise, shaped steel structure or steel-mixed structure is not only very complicated in the use of the structure, but also the deformation and force of the structure during the construction process. The project is a space frame-core structure with special shape, and there are many diagonal truss structures, the top of which is strongly connected with the giant truss or core on the opposite side through horizontal members, forming a “giant structure”. Before and after the joining of the whole structure, there is a big difference in the stress pattern of the main members of the steel truss. Therefore, it is considered that the vertical members and the corresponding floor cover are constructed layer by layer according to the conventional sequence, while the diagonal steel trusses need to be assembled and put into position first, and then the temporary supports are removed and gravity loads are applied after the overall structure is formed. In addition, due to the large difference in vertical stiffness between core and truss, the difference in vertical deformation between the two resulted in the existence of large internal forces in the members connected with the core. For this reason, after referring to the treatment method of super-high-rise extension truss, the design adopts the means of “putting”, i.e., the members adjacent to the core cylinder adopt the practice of post-fixing and post-installation in order to minimize the unfavorable influence of the difference in vertical deformation. In order to reduce the initial structural deformation and internal force generated during the construction process, and at the same time to realize the above “put” requirements, according to the force needs, combined with the feasibility of construction and economy, the design of the proposed accurate simulation and simplified simulation of the two construction assembly program, and the use of finite element program SAP 2000 for calculation and comparison. Accurate simulation scheme means that the deformation and stress in the assembly process are fully considered in strict accordance with the construction sequence, and accumulated in the final internal force calculation and deformation control; Simplified simulation means that most of the components are shaped in the calculation model at one time, and the focus of the analysis is on the influence of the post-installation and post-fixing of some components on the overall structure and related components. The difference between the two scenarios is mainly that Scenario A considers the newly assembled steel joist in cantilevered condition for a period of time before construction is completed, while Scenario B does not consider the effect of this part.
Taking a typical steel joist as an example, the calculation results of the internal force of bars and nodal displacement of the two schemes are specifically analyzed and compared. Due to the special characteristics of the construction scheme of this project, the calculation model and parameters are specially processed during the design to realize the accurate simulation of some steps in the construction scheme.
The results show that there is no significant difference between the internal forces and deformations in the final state of the two simulation schemes, the deformation patterns are similar to the distribution of the internal forces, and the variation of the internal forces in the final state of most of the members is less than 3%. According to the analysis results, the simplified simulation scheme is selected to improve the analysis efficiency under the premise of ensuring the calculation accuracy.