Compressive Behavior Of FRP-rubber Concrete-steel Composite Columns

The thesis presents an experimental and finite element analytical study on the compressive behavior of FRP-confined rubber concrete-encased H-shaped steel columns（FRu CSC）and FRP-rubber concrete-steel double skin tubular columns（DSTC）.The eternal FRP tube provides the confinement to the encased rubber concrete.The H-shaped steel and steel tube placed in the central part of sections mainly afford the axial loading capacity and the rubber concrete is encased between steel and FRP.The above two types composite columns represent excellent performance in ductility and loading capacity by the interactions among three components.Chapter 2 introduces the experimental study on the compressive behavior of FRu CSC.All the test results show that the confinement provided by FRP limit the cracks’ evaluation in the rubber concrete.The confinement offered by rubber concrete prevents H-shaped steel occurring local buckling and overall buckling.The loading capacity of FRu CSC specimens decrease with the rise of replacement ratio for rubber,while the ductility increases with it.All the FRu CSC specimens possess bilinear and monotonically increasing load-strain carves.FRu CSC represents excellent performance in ductility and loading capacity by the interactions among three components.Chapter 3 presents the experimental study on the compressive behavior of DSTC.All the test results show the confinement offered by FRP and steel tube limit the cracks’ evaluation in the rubber concrete as well as FRu CSC.The local and overall buckling of steel tube are restrained,either.The relations between replacement ratio with loading capacity and ductility possess the same tendency with FRu CSC.The substantially loss in loading capacity doesn’t occur in high replacement ratio,which can be attributed to the better confinement of DSTC sections.All the DSTC specimens possess bilinear and monotonically increasing load-strain carves.In chapter 4,the finite element analysis software ABAQUS is used to analyse the compressive behavior of FRu CSC and DSTC.The material property of confined-rubber concrete adapts the constitutive model for FRP-confined concrete.The load-axial strain carves and axial-hoop strain carves obtained from finite element analysis possess same tendency with test results,though the load is higher than test results.To precisely modeling the behavior of FRP-rubber concrete-steel composite columns,it’s necessary to make further improvement in the constitutive model for FRP-confined rubber concrete.In chapter 5,the replacement ratio-related parameter introduced in Chan’s stress-strain model for FRP-confined rubber concrete is refined.Then the refined model is adapted to predict the loading capacity and axial-hoop strain relation for composite columns.The stress-strain models introduced by Chan and Teng are used to compare with the refined model.The results show the refined model is available for loading capacity and axial-hoop strain relation analysis of FRu CSC and DSTC.