Study On Behavior Of H Steel Partially Encased Composite Short Columns Subjected To Biaxial Compression

H steel partially encased concrete composite (PEC) column is a configuration consisting of welded H-shaped steel section with concrete cast between the flanges. Concrete cast between the flanges can effectively improve the resistance to local buckling. Transverse links between the flanges at the regular intervals tend to provide some confinement to the concrete, thereby to improve the ductility of these columns. In the paper, H steel partially encased concrete composite columns are denominated for PEC columns.In this paper, a theoretical analysis for the local buckling of the partially encased concrete composite columns is presented. As for the composite columns,concrete could be regarded as a rigid material. For flange of H steel,the convex occurs when a thin plate is filled with rigid materials,and the steel may only buckle locally away from the rigid materials. Based on small deflection theory, local buckling stress of flange plates with rigid bracing under uniform compression is calculated by Rayleigh-Ritz method, and the local buckling coefficient is obtained.An experimental result of H steel partially encased concrete composite short columns subjected to biaxial compression is presented. The experimental program includes 12 composite columns that are designed taking width-to-thickness ratio of the flange,eccentric angle,eccentricity as the factors. Failure models,failure behavior and bearing capacity of the PEC short columns are explored, the buckling model of the flange is verified. The results showed that: width-to-thickness ratio of the flange and eccentricity are the main factors that affect bearing capacity of the PEC short columns. The bearing capacity increases as width-to-thickness ratio of the flange decreases; The bearing capacity decreases as eccentricity increases.Through the test and theoretical analysis, a formula calculating the ultimate bearing capacity of PEC short columns subjected to biaxial compression is proposed. The results calculated by formula correlate well with experimental results.