Tall Building Structure's Additional Layers Retrofitting And Elasto-plastic Analysis

In recent years, with the development of society and improvement of people's living standard, people on the function requirements of building structure is higher and higher, such as the building area, storey height, building facade, using functional partitioning, etc. This makes the renovation project of building additional layers develop rapidly. In the renovation project of building additional layers, adding layers with steel structure put up prominent advantages, which is used in common. But with the steel structure adding layers, quality and stiffness of structural integrity occur mutations, make the response of whole structure (under horizontal seismic action and horizontal wind load) change greatly and outstanding in high-rise, ultra-high buildings. However, this kind of structure's seismic performance study is less in China at present, and no corresponding standard and technical procedures to specify. So the paper takes engineering background, and study in this problem. This paper focused on the following job:1. Aim at one high-rise framework-core-tube structure model, which is a nonlinear three-dimensional finite element model. Exerted gravitational loading, static analysis, through the structure strain change along vertical deformation and stress distribution characteristics, we found that the equivalent stress and deformation change gradually along the structure height. This suggests that the adding layers project, the layer design and the technology of the engineering are reasonable and effective.2. ANSYS FEM software is used to set up the structure model, proceeding modal analysis on natural vibration period and vibration model. The results were compared with PKPM to show the model's reasonable. It shows steel structure main influence structure additional layers high vibration modes, and has a little affect on low vibration.Similarly, the results also show that the produced "Bian Shao effect", which result from steel structure's quality and stiffness mutations, is by structure's high vibration modes.3. ANSYS FEM software is used to import El Centro and Taft acceleration time-travel curves, which are used in 7 degree film, proceeding elasto-plastic analysis, and compared with the result of PKPM software earthquake static effect, the layer displacement calculation results contrast between two software shows it is consistent, but contrary results occurs in ISDA. So for the similar project design auxiliary FEM analysis is needed.4. Seven degree rarely met earthquake acceleration time-travel curves are imported respectively, taking the structure model for dynamic elastic-plastic time history analysis in two waves, it is concluded that the incentive, the structure of the deformation and displacement angle between the layers of seismic code all meet current demand, but under different wave, seismic response put up obvious difference, and El Centro wave emerge further intensity than Taft wave.5. Larger seismic peak acceleration time-travel curves than seven degree of severe earthquake imported, to look for structure's first plastic films during the earthquake, and it shows that the foremost plastic film appeared in the root segment of the structure.Yet the plastic is so smaller than leading to capacity loss. And combined with the rarely met intensity analysis, the plastic region develops only upward along the shear wall, which suggests this regional should be strengthened appropriately in design.6. On the premise of other factors fixed, double the frame column size, and then import earthquake waves to analysis. The results show that simply increase the steel structure's anti-lateral stiffness cannot make structure stiffness and quality reached uniformity along structure height. In order to be beneficial to anti-seismic, some measures should be taken to facilitate continuity change in the design.7. Under different seismic wave incentive, the trend of layers displacement change is bottom-up increase gradually, to the top floor the maximum displacement occurred. And the maximum displacement angle occurred in 19 layers. Above all, tall building structures in horizontal earthquake effect, its overall displacement curve increased with the buildings, and the trend of displacements angle variation along the height direction revealed a bottom-up reach a certain degree increased rapidly, after the trend began to decrease, the turning point occurred in structure, accord with central high-rise structures deformation regularity.