LATERAL-TORSIONAL BUCKLING STRENGTH OF WELDED I-GIRDERS UNDER MOMENT GRADIENT.

The authors report the results of eight tests carried out to investigate the effect of a moment gradient on the ultimate strength of welded I-girders with intermediate transverse stiffeners. The first four tests were under one end moment, and these tests correspond to a half-segment of a girder which failed by lateral-torsional buckling after being subjected to a central point load. The second four tests were under a uniform moment, and these tests correspond to buckling tests of the central segment of a laterally continuous girder. The points of load application and the two end supports were clamped laterally and rotationally. The second four specimens were subjected to two point equal loads. The cross-sectional dimensions of the girders were proportioned to prevent local torsional buckling of the compression flange, and the web width-thickness ratio was kept constant and equal to 118 for all eight specimens with sigma //y equals 320 N/mm**2.