Static Behavior Of L-shaped And T-shaped Concrete-filled Steel Tubular Columns Under Different Loading Angles

L-shaped and T-shaped concrete-filled steel tubular columns have the advantages of avoiding edges and corners in building structures and improving indoor area,etc.They can be used for corner columns and side columns in structures,and are favored by many researchers and designers.Such specimens are often subjected to bidirectional loads as side columns or corner columns in service,so it is necessary to investigate the effects of different loading angles.In this paper,the static properties of L-shaped and T-shaped concrete-filled steel tubular are studied.The main work contents are as follows:(1)Finite element models of unstiffened,stiffened,multi-cell L-shaped and T-shaped concrete-filled steel tubular short columns under axial compression were established.103 experimental examples were collected for calculation,and the finite element calculation results were in good agreement with the experimental results.(2)804 examples of axial compression parameters with a wide range of parameters were analyzed,and the results of EN1994,Wang and other design formulas were compared with the finite element results,and there was a large deviation between the results.Based on the regression analysis,the design formulas for the ultimate bearing capacity and axial stiffness of the stiffened,stiffened,multi-cell L-shaped and T-shaped CFST short columns with high accuracy and covering a large parameter range are proposed.(3)In this paper,the pure bending test of 11 L-shaped CFST specimens(including 5stiffened,5 multi-cell and 1 unstiffened)and 11 T-shaped CFST specimens(including 5stiffened,5 multi-cell and 1 unstiffened)were carried out to investigate the effects of loading angles and different section forms.The failure mode,bending moment-deflection curve,deflection,strain,flexural stiffness and flexural bearing capacity are obtained.(4)The finite element analysis model of pure bending was established by using the finite element software ABAQUS.The residual stress and cold-bending strengthening effect were considered,and the calculated results were in good agreement with the experimental results.A simplified calculation method for the flexural capacity of L-shaped and T-shaped concrete-filled steel tubular under different loading angles was obtained by considering the influence of loading Angle on the zero degree flexural capacity.(5)For 16 L-shaped concrete-filled steel tube(including five stiffened,more than five rooms and a no rib)specimens and 14 T concrete filled steel tube(including 5 stiffened,5multi-cell and 1 unstiffened)bias of the test specimens study,this paper studies the loading Angle,slenderness ratio and eccentricity parameters affect the performance of L-shaped and T-shaped concrete-filled steel tube bending,the load deflection curve,the deflection curve,the curve of load and strain and strain distribution curve.(6)A three-dimensional nonlinear finite element model considering residual stress and cold-bending strengthening effect is established to simulate L-shaped and T-shaped concrete filled steel tubular specimens with bias pressure.The finite element simulation results are in good agreement with the experimental results.