This paper presents an experimental study on the flexural behavior of encased flat cold-formed steel sections FCFS and perforated
cold-formed steel sections PCFS. A full-scale eleven specimens were prepared and tested till failure. One specimen
without a steel cold-formed section was tested as a control beam. Six specimens with flat steel cold-formed sections were tested to
figure out the enhancement effect of section area and position. Finally, four specimens with a new shape of perforated steel
cold-formed sections were tested with different positions. Cold-formed steel section height, flange width, and position are
the main parameters studied and investigated. The ultimate load and vertical deflections were recorded and investigated.
Also, modes of failure of the control and composite concrete beams were studied. From the experimental investigations, it
has been observed that there is a significant increase in the ultimate load of composite beams with a perforated steel cold-formed
section. A significant increase in the ultimate load was observed for specimens with perforated steel cold-formed section