Theoretical And Experimental Research On Static Stability Of Casing Components

According to the phenomenon that the compression member is prone to instability in the structure of the bar system,the corresponding constraint instability component is generated.The limited instability component is applied to a lot of engineering practice,and achieved good results.The sleeved column is a control stabilizing component,which consists of a gap between the inner core and the sleeve.The sleeved column has the characteristics of stable control and excellent hysteresis performance,etc.The inner core and the sleeve are responsible.The inner core is subjected to axial load,and the sleeve constrains the buckling deformation of the inner core,which significantly improves the bearing capacity of the inner core.In the case of accidental loading,the sleeved column can utilize the energy generated by the instantaneous load of the inner core buckling deformation,reduce the dynamic response of the structure,and reduce the damage degree of the whole structure.Through the previous theory and experimental study,it is found that local buckling is easy to occur under axial load,which greatly reduces the bearing capacity of casing components.Therefore,it is necessary to study the deformation and internal force of the inner core extension segment to the sleeved column,so as to reasonably design the sleeved column and strengthen the connection structure between inner core and the end of the sleeve.At first,this paper put forward considering the mechanical model of not contact?point contact and line contact between the inner core extending from the inner core and the sleeve.The deformation of the inner core under axial load is studied by using linear elastic deflection theory in the case that the inner core has no initial bending and initial bending and the sleeve is flexible and rigid.Thus,the calculation formulas for the physical quantities of the core and the sleeve load-axial displacement,deflection,bending moment and shear force are derived.Then,the mechanical models in the literature [70] and the literature [71] is used to verify the correctness of the mechanical model in this paper.And by comparing the different stiffness of the core and the sleeve,the difference between the two mechanical models indicates that the extension of the inner core has a significant influence on the deformation and stress of the sleeved column.The following results can be obtained: 1?When the axial pressure is certain,the sleeved column with the protruding segment of the inner core has a larger bending axial displacement,which significantly reduces the nonlinear axial stiffness of the sleeved column.2?The contact reaction between the inner core and the sleeve end is significantly increased with the extension of the inner core,and with the increase of axial pressure,the contact reaction force increases significantly.3?The extension of the inner core has significantly improved the shear and bending moment of the inner core,especially when the ratio of the core and sleeve's bending stiffness is relatively large,the increase of bending moment is more significant.At last,based on the previous theoretical analysis,it is concluded that the force between the inner core and the end of the sleeve is under the action of axial pressure.Three different types of end parts are proposed to strengthen the construction measures,and compared with the structural measures in the previous literature,the reasonable end construction measures of the sleeved columns are obtained.It is shown that the application of bushing to the connection between the inner core and the sleeve can improve the phenomenon of local buckling in the extension of the inner core,so that the bearing capacity of the sleeved column can be effectively exerted.