LOCAL BUCKLING BEHAVIOR OF HIGH STRENGTH STEEL PLATE WITH UNILATERAL RESTRAINT AND TRILATERAL SUPPORT

Partially encased composite (PEC) column flanges can be classified as a flat plate fixed on three sides, free on the other side, and restrained by concrete on one side outside the plane. The local buckling of this kind of plates can be avoided by limiting the width-to-thickness ratio. To obtain the width-to-thickness ratio limit of such high-strength steel plate, the elastic-plastic buckling stress of plate under uniform compressive stress is derived by using Bleich approximate calculation method, and the approximate solution of width-to-thickness ratio limits are obtained, based on the elastic-plastic local buckling theory of a thin plate, combined with Ramberg-Osgood constitutive model of high-strength steel. Furthermore, the numerical tests of axial compression of PEC columns with high-strength steel are carried out by the finite element method. The accuracy of the approximate solution of the width-to-thickness ratio limits proposed is verified by the finite element results and by the existing experimental results. The comparison with the relevant codes shows that: the unilateral restraint action of concrete can increase the width-to-thickness ratio limits of the high-strength steel plate supported on three sides by 39%; the width-to-thickness ratio limits of high-strength steel plate with unilateral restraint fixed on three sides free on one side calculated by the approximate formula proposed is 19% smaller than that of the Australian code AS/NZS2327: 2017 and only 5% less than that of the European code EN 1994-1-1. It is suggested that the width-to-thickness ratio limits of a high-strength steel plate with unilateral restraint fixed on three sides free on one side can be safely taken as the smaller value of the calculation results of the approximate formula proposed and the calculation result of EN 1994-1-1.