| Over the past years,a large number of super-tall buildings have been constructed in earthquake zones in China,which makes their seismic performance become a research hotspot in engineering and academic communities.Outrigger truss+core tube is a kind of structural form widely used in super-tall buildings.Existing super-tall buildings generally have high seismic reserves,and although they will not collapse under the effect of a rare earthquake,there it remains a risk of serious damage to the elements,resulting in serious economic losses.In order to improve the ductility and energy dissipation capacity of the structure and to establish post-earthquake easily recoverable functional structure,the multiple energy dissipation mechanism of the structural system are established.In this thesis,a frame-steel plate wall core tube structure with Buckling-Restrained Brace outrigger truss was taken as the basic research object,and a series of studies were carried out on its seismic performance,including deformation characteristics,internal force distribution,energy dissipation distribution,structural damage,yielding mechanism of the structure,etc.The main work and research conclusion include:（1）A design method for BRB outrigger truss based on seismic performance objective was proposed.The method is based on the results of basic earthquake elastic calculation for common outrigger truss,and its reliability was verified by ABAQUS elastoplastic analysis.（2）Taking a 56-storey frame-steel plate wall core tube super-tall structure with outrigger truss as the basic research object,the comparative study of the seismic performance of the structure with outrigger truss inclined bracing using normal bracing and BRB was carried out respectively.The analysis results show that even with the use of steel plate shear walls with good ductility,the BRB outrigger trusses still exerted a good energy dissipation effect,optimized the plastic energy dissipation distribution of the structure,reduced the damage of other critical members and protected the critical members.（3）Keeping the BRB outrigger truss-steel plate wall core tube unchanged,the frame was redesigned as a mega frame,and its seismic performance was systematically studied by using YJK and ABAQUS software.The results show that the mega frame increases the abrupt stiffness effect of the structure.Compared with ordinary frame structure,the stiffness,seismic action and deformation of the mega-frame structure are larger.Under some rare earthquakes,the giant column will yield earlier,resulting in the structural stiffness and load carrying capacity declining rapidly,which should be paid attention to in the design.In addition,the results of the energy dissipation analysis show that the energy dissipation effect of using BRB for middle truss diagonal web members is small.（4）A 50-storey frame-double core tube structure with BRB outrigger truss was designed by performance-based design method against the background of a super-tall building in8-degree zone.The model of vibration,deformation characteristics,internal force distribution and structural response under different levels of seismic action were obtained by means of modal decomposition response spectrum analysis,dynamic time history analysis and static elastic-plastic analysis.The analysis results show that the main energy dissipation members of the structure under rare earthquakes are,in order,embedded steel plate,connecting beam,frame beam and energy dissipating support,and the structure has multiple energy dissipation mechanisms,which can effectively reduce the earthquake damage of the key vertical members.The structural damage analysis indicates that the connecting beam between two core tubes is the weak part of the structure.In general,the structure has a high level of performance,with a high seismic reserve,a reasonable yield mechanism and structural components that meet the expected performance objectives,and accords with the conceptual design of multi-channel seismic defense line. |
PDF Full Text Request