| Recently, High-rise buildings are developing very quickly to satisfy the development of production and peoples’ living needs. Due to the knowledge of seismic activities in china, all buildings especially tall buildings are considering all seismic loads and standards in its design; therefore I exploit this point to study considered seismic load tall building with and without setbacks to provide more understanding about the performance and response of tall building resisting earthquake. In this time frame-shear wall with setback structure system are widely used in high-rise buildings because it has flexible layout features to design more free space which provide more convenience to the costumers. This study firstly introduced the high-rise building dynamic forces and the building structure setback irregularity; in addition resisting seismic design principles are listed according to Chinese code. In this study finite element method is used and carried to overall tall building structure dynamic analysis by using SAP2000 V16.1 commercial software with nonlinear time history analysis and windows 7 Excel software to complete the seismic analysis, this study is presenting two main analysis parts as shown below:First, this part is mainly focusing to analyze the seismic performance for 34 storeys with total height of 106.4m frame-shear wall Reinforced Concrete(RC) tall building structure with setback on its horizontal plan and vertical section to study how the setbacks are impacting on tall building. The analysis includes the modal vibrations period ratio analysis; model weight, mass and mass centre calculation, model displacement analysis(roof total displacement analysis; storey drift and drift angle analysis and displacement ratio analysis) and the model internal forces analysis(earthquake action horizontal force P of the model; model X and Y directions shear forces; model X and Y directions bending moment forces; model X and Y directions torsion forces and Frame-shear wall tall building model lateral stiffness ratio2?). All these results are carried out by using three earthquake accelerations(El Centro; Altadena and ARRY06 accelerations) carried on nonlinear time history analysis in SAP2000 V16.1 software.This part analysis result shows the internal forces have sudden changes in the setback level with the three accelerations, this lead 7th storey to be weak storey during earthquake actions, the tall building damage and deformations characteristics under earthquake action usually start on the weak storey, and 7th storey weakness is influencing the tall building resisting seismic performance may be lead to serious deformation during earthquake action.Second, the present study also focus to analyze the relative earthquake performance for the tower portion of a 34 storey Reinforced Concrete(RC) with 106.4m total height frame-shear wall buildings with and without setbacks subjected to an earthquake excitation scaled down to be of peak ground acceleration appropriate for China, and analyze the setback influence on this high-rise building to identify weakness positions in the high-rise building structure. The comparison is used SAP2000 software V16.1 for the elastic calculations aid to assess nonlinear time history analysis for their applicability to tower models(first model with setbacks, second model without setback) of height-rise frame-shear wall building under same conditions of the site category, earthquake El Centro acceleration type and same standards of the structural design. This part of the study is carried out to judge how the vertical(elevation) setback impact in tall building resisting seismic actions. This part of the study proves the setback directly impact on the tall building, where the tall building displacement is reduced, while the tall building internal forces are increased by applying setback to the tall building design. |
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