ABSTRACT
Floor joists of cold-formed steel (CFS) structures utilize large web openings to keep the floor height to a minimum. Cost-effective solution to restore capacity is to affix reinforcements around the openings. Twenty-three laterally braced simply supported CFS joists were subjected to uniformly distributed loads until failure. Program considered solid sections, circular and square web openings (65% of web depth) and sections with reinforced web openings. The reduction in the flexural capacity is < 15%. Twenty-seven joist sections were subjected to shear tests to establish the shear capacities of sections having a large opening and reinforced opening. The reduction in the shear capacity was as high as 60%. Vierendeel type reinforcement system restores the original shear capacity. Recommended prescriptive solutions are, provide flexural reinforcements for opening in the mid 40% region of a joist and provide shear reinforcements for openings in regions outside the mid 40% region (defined as “Shear Zone”).
