Theoretical Analysis Of Hysteretic Behaviour Of Concrete Filled CFRP-Steel Tublar Beam-Columns

Concrete filled steel tubular(CFST)structures have been widely used in high-rises,super high-rises,underground structures,factories,bridges,and so on.The possibilities have been increasely used in engineering design and construction,changed building function,suffered from disasters(for example earthquake,fire disasters),and so on.The strengthening and restoration of Concrete filled steel tubular(CFST)structures were generated.The most commonly used material was Carbon fiber reinforced polymer.CFRP gets attention with its advantages such as lighteness,high strength,corrosion stability and facility in engineering.CFRP and concrete filled steel tube were combine,CFRP could provid constraining force with steel tube together to core concrete and the bearing capacity of concrete filled steel tubular structures were improved.Because of the fracture strain of CFRP was small,belongs to the typical brittle failure.The steel tube with good ductility could remedy the deficiency of CFRP constrain concrete and made the destruction of the structures have a certain ductility.The seismic behaviour of structures have been increased.Hot spot of research on concrete filled CFRP-steel tubular structures were formed at home and abroad.With theoretical foundation established the concrete filled CFRP-steel tubular structures were widely used,especially in ocean engineering and bridge engineering.Domestic and international researches for concrete filled CFRP-steel tubular structures focused on the static test and theory analysis.But the Hysteretic mechanics behaviour research is various.This thesis studied on hysteretic mechanics behaviour of concrete filled CFRP-steel tubular beam-columns was through ways of simulated method of finite element and theoretical analysis.To provide more reference for concrete filled CFRP-steel tubular structures design should learn more hysteretic mechanics behavior.The main aspects of research work in this thesis are listed as follows:1.At the beginning of this thesis introduced the characteristics of concrete filled steel tubular structures and concrete filled CFRP-steel tubular structures,the history development and the relevant researches of concrete filled CFRP-steel tubular structures.The research purpose,content and research methods were simple and clearly illustrated.2.The test was designed a total of 24 specimens,respectively for 12 Concrete tilled circular CFRP-steel tubular specimens and 12 Concrete filled circular CFRP-steel tubular specimens.This thesis briefly illustrated test device,loading system,stop standard and the measured content of the specimens.3.Hysteretic curves of concrete filled CFRP-steel tubular beam-columns were caluclated the finite element software-ABAQUS.The Bauschinger effect and strengthening effect of steel,the carrying capacity decline and stiffness degenerate of concrete under cyclic loading were considered accurately in this analytic model.Because of the particularity of CFRP materials,element was choose M3D4R.The predicted load versus deformation relationship curves are in good agreement with those of tests.The reliability of finite element model was verified.4.On the basis of the model reliability was verified,this thesis deeply analyzed the throughout loading history of concrete filled CFRP-steel tubular beam-columns,the interactional action,cooperative working mechanism and stress behaviour among CFRP,steel tube and core concrete.To systematically consider the various parameters influence on the P-? skeleton curves,the parameters of concrete filled CFRP-steel tubular beam-columns were changed,for example the number of piles of the longitudinal CFRP(m')and the transverse CFRP(m),steel yield strength(fy)and so on.