Elasto-plastic Analysis Of Concrete-filled Steel Tube Frame-wall Structure

During the strong earthquake, the strueture will be Elasto-Plastie, the stiffess is ehanged,and at the same time Plastic stress will be redistributed.the elastic analyses ignore some important properties of struetures,such as dynamic and nonrigid characters.so it is suitable for the short natural period buildings.The great deviation will be obtained for muti-storey and high-rise and flexible structural system.The response spectrum method can take into account the relationship between the dynamic properties and the earthquake action,while it can not give the whole procedure of the structural seismic responses.The interal force and deformation state of structural elements can not be gotten.To study and calculate the elasto-plastic deformation for tall buildings,nonlinear analysis is necessary.For the moment,the major nonlinear analyses analyses are the nonlinear dymamic analysis and nonlinear static push-over analysis.The static push-over procedure is viewed as simplified analysis method,except for taking into account of the force-redistribution following yielding,in many conditions it can predict more adequate information than dynamic nonlinear time history analysys procedure,these information can detailed describe comprehensive performance of the structure subjected to earthquake. Push-over analysis procedure plays essential role in performance based seismic design.While there are some theoretical drawbacks of push-over analysis procedure,which make it apply to the structure that oscillates predominantly in the fundamental mode,when push-over analysis procedure is used to estimate high-rise structure that the higher modes effect could not be ignored,this method would result in some deviations,even draw some wrong conclusions.By the nonlinear dynamic analysis,the time-varying displacements,velocity and accelerations may be calculated by direct substitution.And so the interal varied stress and the damaged process of structural elements during the elastic and nonelasticstage can be found out.this method is an accurate and realistic prediction of the seismic behaviour of reinforced concrete structures.In fact,due to the need for implementing complex behavioural models,such analysis requires a significant computational effort,especially for large multistory building;furthermore,besides the dependence on the structure modeling,the results depend on the assumed input ground motion.for these reasons,it is not be widespread used.Thoughout the advantages and disadvantages of nonlinear static pushover analysis and nonlinear dynamic analysis,in this paper three typical earthquake records and five typical load patterns on two RC buildings according to the code for seismic design of building (GB50011-2-010were chosen to analyse16-story r/c symmetrical plane frames.