Numerical Simulation On Structural Performance Of Super Tall Building With Setbacks By Stage Construction Analysis Method

With the rapid development of China's economy and society,the construction of super high-rise buildings in China is increasing rapidly in recent years.The structural system of such tall buildings is becoming more and more complex.The common characteristic of such super-tall buildings includes long period in construction and complicated construction technology.Those factors,which include the loading,different construction methods and construction sequences,have great influence on the structural deformation and stress state for super tall buildings during the construction period.Therefore,it is very important to conduct the numerical simulation analysis of structural performance of super tall buildings.Such research studies could provide the guideline for the construction process and assure the safety of super tall building during the construction period.The dissertation presents a study in the numerical simulation of structural performance of Eastern Building of Huarun Center in Nanning City.Some key influence factors for the structural behavior of this super tall building during construction period are investigated.The main contents discussed in the thesis are as follows:The various finite element models for this tall building at different construction stages are first established by finite element software ETABS,and the influences of construction progress and time-dependent properties of concrete materials are considered in the construction simulation.The trend of structural deformation during construction and the first20 years in operation state are investigated.Results shows that vertical deformation of structure suggests a “fish-bellied”curve,in which vertical deformation of the middle floors are larger than those of the low and the top floors.The shrinkage and creep of concrete have significant effect on the deformation.The vertical deformation and horizontal displacement continue to increase as the construction time goes on.Due to the setbacks of the buildingand vertical deformation difference,the horizontal displacement appears and its maximum value occurs at the middle floors.The comparison in the numerical analyzed results in the horizontal displacement and vertical deformation was conducted with different shrinkage and creep models such as CEB-FIP90,ACI209-92 and B3 model.The compared results shows that the deformation trends obtained from the three models are in good agreement,but the values are not exactly the same.The numerical analysis of structural performance for the whole structure under the finalized loading was conducted.The stage construction analysis considering the effect of the shrinkage and creep in the concrete members or not are also investigated.The numerical analyzed results show that only the stage construction analysis method considering the effect of the shrinkage and creep can simulate the actual structural performance of the super tall building precisely.After comparing the simulation results with the measured data,it is found the trends of deformation development from both methods are in good agreement.The effect of construction speed and construction stories of the in-core tube ahead of the outer frame on the structural behavior of the constructed building are discussed.Numerical analyzed results show that the construction speed has little influence on the vertical deformation or horizontal displacement of the studied building.With the increase in the construction stories of the in-core tube ahead of the outer frame,vertical deformation of the in-core tube gradually increase.Meanwhile the vertical deformations of outer columns gradually decrease.The number of construction story for the in-core tube ahead of the outer frame has little influence on the horizontal displacement of outer columns,but it has significant influence on that of in-core tube walls.The influence of the suitable construction time when the installation of outrigger truss is necessary for the constructed tall building is also evaluated in this dissertation.The numerical results provide the guideline for the optimization of outrigger truss installation schedule.Finally the structural performance due to the temperature difference in the steel members between the day and night sides was also discussed.The numerical analyzed results show that temperature difference has significant influence on the internal force distributions and deformations of outer column members.