Dapeng Town Industrial Park, Tongshan District, Xuzhou City, Jiangsu Province, China
The super high-rise, special-shaped steel structure or steel-mixed composite structure is not only very complex in the structural use stage, but also the deformation and stress of the structure in the construction process are particularly complex. The project is a steel frame-core tube structure with special shape, and there are many oblique truss structures, whose top is strongly connected with the giant trusses or core tubes on the opposite side through horizontal members to form a “giant structure”. Before and after the closure of the whole structure, the stress patterns of the main members of the steel truss are very different. Therefore, the vertical members and the corresponding floor are considered to be constructed layer by layer in the conventional order, while the oblique steel truss needs to be assembled in place first, and the temporary support is removed after the overall structure is formed, and the gravity load is applied. In addition, due to the large difference in vertical stiffness between the core tube and the truss, the vertical deformation difference between the two causes large internal forces in the components connected to the core tube. To this end, after referring to the treatment method of the cantilever truss in the super high-rise, the design adopts the “put” method, that is, the members adjacent to the core tube adopt the practice of post-fixation and post-installation, in order to reduce the adverse impact of the vertical deformation difference. In order to reduce the initial deformation and internal forces of the structure generated in the construction process, and realize the requirements of the above “put”, according to the force needs, combined with the feasibility and economy of the construction, two construction assembly schemes of accurate simulation and simplified simulation are designed and developed, and the finite element program SAP 2000 is used to calculate and compare. Accurate simulation scheme means that deformation and stress in the process of component assembly are fully considered in strict accordance with the construction sequence, and are accumulated into the final internal force calculation and deformation control. Simplified simulation means that most of the components are formed in the computational model at one time, and the analysis focus is focused on the influence of the post-installation and post-fixation of some components on the overall structure and related components. The difference between the two schemes mainly lies in that scheme A considers that the newly assembled steel truss is in the cantilever state for a period of time before the construction is completed, while scheme B does not consider the influence of this part.
Taking a typical steel truss as an example, the calculation results of internal forces and joint displacements of the two schemes are analyzed and compared in detail. Due to the particularity of the construction scheme, the calculation model and parameters are specially treated in 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 two simulation schemes in the final state of internal force and deformation, and the deformation morphology and internal force distribution are similar. The variation range of internal force in the final state of most components 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.
