THE BEHAVIOR OF ECCENTRICALLY RESTRAINED I-SECTIONS SUBJECTED TO AXIAL LOADS

The axial load capacity of a strut is commonly defined in terms of a s lenderness parameter, which is a function of the distance between rest raints. Theoretical and experimental investigations into strut behavio ur have concentrated on cases where the restraints are placed in such a manner as to prevent displacement of the centroid of the section. In some practical applications, restraints are placed in such a manner a s to restrain only part of the cross-section and displacement of the c entroid is still possible. Common practical examples of such struts ma y be found in industrial-type portal frames, where some difference of opinion exists as to the restraining action of the sheering rails whic h are attached to one flange only. Existing knowledge of strut behavio ur is not directly applicable to such cases Experimental studies were conducted with a view to developing a theoretical model reflecting the behaviour of I-columns where intermediate restraints ale attached to one flange only. Cases considered include one, two and three intermedi ate restraints and two different section sizes were used. Section para meters influencing the behaviour over a range of slenderness ratios ar e discussed in this paper and comparisons with a theoretical model are made. Some design curves are presented and general observations regar ding the behaviour of such struts are indicated.