Behavior of Rectangular Concrete-encased CFDST Long Columns under Axial Compression
In order to analyze behavior of rectangular concrete-encased CFDST long columns under axial compression,and a practical calculation method for axial compression stability loading capacity is proposed.A finite element model of rectangular CFDST long column is established on ABAQUS,and its working mechanism was analyzed under different parameters.Finally,by adopting the principle of superposition and combining with the relevant existing codes,the formulae for calculating the axial compression stability load capacity applicable to rectangular concrete-encased CFDST long columns are proposed.Results showed that the damage pattern of the rectangular concrete-encased CFDST long column is characterized by deflection in the middle of the column and eventual damage due to loss of stability.The length to slenderness ratio(λ)and the strength of the outer concrete(fcu,out)are key parameters affecting the top axial compression load of long stacked columns.As λ increases from 29 to 42 and 55,the top load capacity decreases by 7.3%and 15.3%respectively;as fcu,out increases from 40 MPa to 60 MPa and 80 MPa,the top load increases by 21.4%and 44.8%respectively.The mean and the coefficient of variation of the ratio between the simplification formula for the axial bearing capacity and the results derived from the FEM simulations are 0.927 and 0.017 respectively.The conclusions show that rectangular concrete-encased CFDST long columns have excellent compressive properties and initial stiffness,and the simplified calculation formulae can provide basis for calculation in practical engineering.
rectangular concrete-encased CFDST long columnsaxial compression behaviorstable bearing capacityfinite element analysis
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