Research On Seismic Resilience Of Mega-frame Structure

At the era of increasingly developmental population and economy density,the structure should guarantee the safety of life,take into account of economic loss,as well as ensure the construction a good performance of resilience when earthquake happened.As a new type of structural system,mega-frame structure has a prosperous development of highrise buildings.Related researches have been carried out by foreigner and domestic scholars,which show its importance in the following study.Based on the major projects of the national natural science foundation : “Research on Seismic Energy and Collapse Analysis of Super High-rise Mega-frame Structures with Vibration-Absorption”,“Study on the Seismic Behavior and Earthquake Resilience of the Mega-frame Structures with Vibration-Absorption Substructure”,and “Study on performance-based seismic design of the Mega-frame Structures with VibrationAbsorption Substructure”,this paper takes the mega-frame structure with and without vibration absorption substructure as the research object,the resilience performance of the mega-frame structure as guiding ideology.In order to study the damping effect of megaframe structures with vibration-absorption substructure,the ABAQUS is used to establish the refined finite element model of the two kinds of mega-frame.In order to study the contribution of the mega-frame with the vibration absorption substructure to the resilience,the performance models of the two kinds of mega-frame are established by PACT.The main research results are as follows:(1)With a small amount of reduction of mass ration,the model can achieve greater range of adjustment of frequency ratio.Considering the excellent anti-collapse performance from the reasonable design of the super high-rise structure,and acceleration sensitive non-structural components of the damage,as an important indicator of resilience,the absolute acceleration of the floor is selected as the evaluation index.Our study chooses11 ground motion records as basis,and adjusts the acceleration peak to the magnitude of the seven-magnitude under middle seism,whereafter,utilizes the time-history analysis to verify the mega-frame with single vibration absorption substructure under different frequency ratios.The results show that,on the whole,the vibration absorption structure at different frequency ratios has a certain control effect on the absolute acceleration of the floor.When the frequency ratio is 5,the effect is at its optimal,and the reduction effect of the absolute acceleration of the floor in the middle of the structure can be exceeded 10%.(2)The collapse of the buildings is the main cause of casualties.If structure collapses,its resilience is not existed.Based on the incremental dynamic analysis,the collapse vulnerability of two kinds of structures is analyzed by using peak ground acceleration as the intensity measure and the maximum inter story displacement angle as damage measure.The result shows that both of two kinds of structures have high anti-collapse ability,even in the maximal considered earthquake.Meanwhile,it illustrates the rationality of floor absolute acceleration selection when optimizing damping effect.Mega-frame structures with vibration absorption substructure has higher collapse resistance.(3)Compared with the inter story displacement angle,the maximum acceleration of the floor and other indicators,economic losses and casualties after the earthquake is a more direct way to reflect the resilience of the structure,which is easier to accept.Performance model of mega-frame structures with and without vibration absorption substructure model,combined with the structural response data,examines the resilience of the important indicators which involves in economic losses and casualties,as well as make a comparative analysis utilized Performance Assessment Calculation Tool on the basis of FEMA P-58.The results show that,under the impact on service level earthquakes,the mega-frame with and without vibration absorption substructure will generate a certain degree of damage,which needs to be repaired.From the median value of repair costs,mega-frame structures with vibration absorption substructure has a certain function to improve the resilience.The main repair cost of the structure is spent on non-structural component,as well as most of these components are acceleration-sensitive,which further illustrates the rationality of the floor absolute acceleration selection,as an optimizing index,on the second chapter of this paper.Under the influence of service level earthquakes,the mega-frame with and without vibration absorption substructure generate a low probability of casualties,which can be negligible.