Abstract：Static experiments were conducted to study the flexural performance of 6 cold-formed
steel single-limb C-shape beams and 18 cold-formed steel double-limb built-up I-shape beams. The
influence of span-height ratio, width-thickness ratio, height-width ratio, screw spacing and web
opening size on failure modes and ultimate flexural capacity of double-limbs built-up I-shape
beams are analyzed. It is verified that the flexural capacity of double-limb built-up I-shape
beams was two times that of single-limb C-shape beam. Finite element software ANSYS is adopted to
conduct numerical simulation and influence factors analysis. The results show that the failure
modes of specimens are interactive buckling forms of local buckling and distortional buckling for
flanges and webs. The width-thickness ratio and height-width ratio have a great impact on the
bearing capacity of cold-formed steel double-limb built-up I-shape beams, while the screw spacing
(between 300mm to 600mm) and span-height ratio have less impact. In the practical engineering
design, it is recommended that the web opening form is circular hole and the web hole area ratio
is between 35% and 50%. Additionally, the web hole spacing should be not less than 400mm. On the
basis of strength reduction method for flexural capacity of double-limb built-up I-shape beams,
the strength reduction correction method is proposed to calculate the flexural capacity of web
opening cold-formed steel double-limb built-up I-shape beams.
