Local Press Of Concrete Filled Steel Tubular Short Column Performance Study Based On Multi-section Model

Assembled steel-concrete structural system requires a huge number of nodes,horizontal and vertical joints,whose design directly impact the reasonable stress and overall seismic performance of the system.Assembled concrete-filled steel tube composite shear wall proposed by the research group of professor Su Youpo is a new type of structural system,in which the reliable connection of steel tube concrete joint is a difficult problem to be solved.In this thesis,based on the finite element calculation platform,a multi-section model was established to implement the theoretical analysis and numerical study of axial compression and local bearing capacity performance on the new type of steel tube concrete column joint connecting device.The key parameters of the model are checked and verified based on the previous test results.Main contents include:1)8 domestic and foreign design specifications on the concrete filled steel tube under axial compression bearing capacity are summarized and compared,and the differences among formulas are analyzed separately from the scope of application,confinement effect and formula theory basis.The results show that the ultimate bearing capacity of the steel tube using the foreign design specifications tends to be conservative,while the calculation result using our country' s code is closer to the experimental results than that of using the other 4 foreign countries' codes.2)Based on Open SEES,the full section compression model of CFST short columns and circular hollow sandwich steel tubular short columns is established.The calculation results are generally consistent with the experimental results.The key parameters are analyzed as well using the model.The results indicate that ultimate bearing capacity of the circular steel tube concrete specimens can be enhanced with the increase of core concrete strength,hoop coefficient and yield strength of steel,while with the decrease of radial thickness ratio.Moreover,the increase of the hollow ratio and tube diameter to thickness ratio,as well as the decrease of slenderness ratio,can improve the ultimate bearing capacity of the concrete hollow sandwich steel tube specimen.3)Based on ABAQUS,a multi-section model of circular tube confined high strength grouting material under local pressure is established,to investigate the effects of various parameters on the sensitivity of node connection.The results show that when imposed with local pressure,the ultimate bearing capacity of circular steel tube confined high strength grouting material could increase with increase of the ratio of the height to diameter,steel tube wall thickness and high strength grouting material strength;however,it could be improved with the increase of cutting angle,tube height,thickness and strength of high strength grouting material under local press.