Structural Efficiency of Cold-Formed Steel Beams with Stiffeners in the Web

This paper reports a series of flexural tests at ambient and fire conditions on simply supported cold- formed steel (CFS) beams using two different configurations – with and without web stiffeners. The main objective of these tests at ambient temperatures was to assess the ultimate strength of the beams and to provide a reference for the fire tests. On the other hand, the major purposes of these tests under fire conditions were to assess their critical temperature and critical time as well as to observe the effect of the stiffeners on the beams under different restraining conditions, including no restraints, partial axial restraint to the thermal elongation of the beam and partial rotational restraint at the beam supports. In addition, a comparison of both experimental results at ambient and fire conditions with predictions from currently available design rules is shown. Finally, it is worth mentioning that the use of CFS beams with web stiffeners might not be always a good solution, depending on their slenderness and boundary conditions.