Failure Research Of The Super-high Building Structures Aseismic Design

Nowadays,the number of high-rise building beyond code limits in China is the largest in the world,and around 80%of the super high buildings are located in 7 degree and 8 degree high-intensity earthquake regions.Besides,to make things worse,China is one of the earthquake-prone nations.Due to the fact that the height or complexity of the structural system of these super high buildings is beyond the code limits,research on the risk of the seismic design for them is of great value to improve the seismic performance of these super high buildings.In this thesis,high-rise building beyond code limits are taken as the research object and on the basis of the analysis results of the existing research home and abroad,a risk analysis model for structural seismic design is established,in which several computation methods are employed to analyse the risk of the basic events,basic events for seismic design are identified,logical relationships between the risk factors are defined,computation equations for calculation of the risk probability of basic events are established,and calculation method for the risk probability of the least favourable event is derived.Calculation results of the risk probability of seismic design are obtained,which could serve as the quantitative basis for effectively evaluating the risk probability of seismic design.In addition,based on the quantitative evaluation of the seismic design,the corresponding risk control solutions are proposed.(1)Definition of the basic elements of risk analysis model for seismic design.Based on three levels of seismic fortification,top event,intermediate event and basic event are defined.Drawing rules for fault tree are established and logical relationships between these events are defined.Identification method and evaluation criterion for risk source events of seismic design are established,by which the calculation model for risk probability of basic event and top event of risk sources of seismic design is proposed.Based on the risk analysis results,quantitative evaluation and risk control measures are defined.(2)Identification of seismic design defects.The limit state requirements and specific meaning of all risk sources are defined and the corresponding design indicators are identified through four methods,viz.elastic structural analysis,elastic time history analysis,member checking,and dynamic elasto-plastic analysis.Based on identification results,whether a risk source event is a basic event for seismic design will be determined.(3)Fault tree analysis.According to the limit state requirements of structural seismic design,a specific function of seismic energy corresponding to design defects for high-rise building beyond code limits is proposed to calculate the probability of independent failure of seismic design resulted for each design defect.At last,based on the logical relationships between risk factors that are defined by the fault tree diagram,calculation equations for risk probability of seismic design are derived at each fortification level.(4)Risk evaluation and control.Based on the results of fault tree analysis of seismic design,risk levels of seismic design are evaluated in quantitative form,by which the conclusions for the high-rise building beyond code limits are arrived at.According to defects in structural seismic design,adjust measures for seismic design are established in order to effectively control the risk of seismic design,by which the control effects of seismic design risk are checked.