The Methodology Of Seismic Assessment Of The Resilient Structure

The earthquake resilient structures which need not repair or slight restoration after earthquake can recover their functionality of occupancy.The self-centering structure is one of resilient structures,which can recover its functionality after large earthquake by dissipating earthquake energy,even can repair the structure to initial zero residual drift itself after subjecting large inelastic deformation cycles.Those structures can reduce or eliminate the post-earthquake residual drift,facilitate the instant use of various facilities and decrease economy losses.Many researches which aim at seismic performances of those structures are carried out by domestic scholars,while they often place more emphasis on the capacity of energy dissipation,residual drift,maximum inter-story drift ratio of structures,and the researches of economy losses and casualities of buildings are short.Therefore,the paper address seismic assessment of resilient structures based on the exploration of performance-based earthquake engineering in order to improve methodology of seismic assessment of this type of structures.The contents of this paper are as follows:(1)The FEMA P-58,namely the methodology of seismic assessment of buildings,are introduced detailedly,which provides performance assessment calculation tool(PACT)that can be used to assess the performance of buildings.The five methods which are used for component fragility analysis are introduced at the same time.Moreover,the definition and quantification method of resilience of system are introduced,including the research methods of functionality losses,recovery process and the definition of recovery time of structure during assessment of resilience.(2)The six-story self-centering energy dissipated brace(SCEDB)steel frame model is developed based on the Open Sees finite element software,and the six-story self-centering buckling-restrained brace(SC-BRB)steel frame is also developed according to brace equivalent strength principle.The nonlinear dynamic time history analysis are carried out for two steel frames under frequent,design and rare earthquakes,the engineering demand parameter(EDP)of the structural systems are achieved through those analysises and then put into the performance assessment calculation tool(PACT),the performance measures of buildings under three level earthquakes such as repair cost,repair time and casualties are calculated at last.(3)The downtime,direct economy losses,indirect economy losses and casualties of six-story energy dissipated brace steel frame and six-story buckling-restrained brace are assessed based on the theory of single building losses assessment of pacific earthquake engineering research center(PEER).The engineering demand parameter(EDP)of two resilient structures are obtained under the each ground motion level,finally the recovery time,direct economy losses and indirect economy losses of buildings are achieved based on the theory of performance-based assessment.(4)According to the definition of community resilience and the initial losses and recovery time of two resilient structures which can be obtained from former study of this paper,the post-earthquake resilience of self-centering buckling-restrained brace steel frame and self-centering energy dissipated brace steel frame are calculated based on different recovery functions,the seismic performance and post-event resilience of two resilient structures are analyzed and compared at last.