Tests to investigate the web slenderness limits for cold-formed RHS in bending

Steel beam cross sections are normally classified according to the effect of local buckling on the moment capacity of the section. This is achieved by defining slenderness limits for the flange and the web. This paper describes a series of bending tests on cold-formed RHS to examine these limits. The resulting experimental relationship between web slenderness and plastic rotation capacity is given. It is found that the web slenderness limits in steel design specifications for compact sections are not conservative for RHS when used in plastic design. There is clear interaction between the flange and web slenderness which should be accounted for in the limits. A tentative proposal for a new compact web slenderness limit for RHS is suggested.