Study On Response And Response Control Of Super High-rise Structure Under Far-field Long-period Ground Motion Input

Long-period ground motion is a special type of ground motion,which will bring more serious earthquake damage to structures with long self-vibration period.A large amount of examples have been found of serious earthquake damage cause by long-period ground motion at domestic and foreign.The domestic research on the seismic damage of long-period ground motions started late.The main research directions about long-period ground motions are the difinition principle,input method and structural response.At present,the research on the response control of super high-rise structures under longperiod ground motion is scarce at domestic,and it is necessary to research on as more and more super high-rise structures have been built.The main work of the study is as follows.(1)A super high-rise structure model is designed.The story model method,one of the simplified methods of super high-rise structure,and its improved method are studied.A program is wrote in Matlab based on story model method to accomplish time-history analysis of structure,and the differences of structural dynamic characteristics and dynamic responces is compared.The results show that in the elastic time-history analysis,analysis results of the story model are in good agreement with the finite element model's results.(2)Simplify the super high-rise structure with the story model method,then compare three aspects with inputting far-field long-period and ordinary ground motion: the structural maximum responses and the non-structural maximum responses during earthquake,the response characteristics at the time-domain.The result show that the amplitude of structural responses and the non-structural responses are positively correlated with the value of acceleration response spectrum near the first several period of the structure,meanwhile inputting far-field long-period ground motions can cause serious time delay of the structural maximum responses,and the shaking of structure may last a long time.(3)The damping ratio or the stiffness of the story model is changed to compare the differences between two type of ground motion inputting in the structural and nonstructural maximum responses and the time-domain response characteristics.The results show that structural responses are reduce by increasing the damping ratio.But it's unpredictable by changing the stiffness of structure,as the inherent attribute of structure has been changed,too.(4)The energy-based response control indicator is selected,because of the characteristics of the time delay of the structural maximum responses in the time domain with long-period ground motion inputting.The layout position optimization study is carried out for dampers associated to relative velocity(for example,viscous damper)and dampers associated to relative displacement(for example,buckling restrained braces).It proof that the current damper scheme is also working for far-field long period ground motion.Then the capacity of two types of damper of dissipating seismic energy is compared,the buckling restrained braces exhibit greater energy dissipation capacity than viscous damper braces.