Comparative experimental study on the serviceability and flexural strength of cold-formed steel I-joists with and without stiffened web holes

Cold-Formed Steel (CFS) has emerged as a preferred material for low-rise building construction, as well as for roof and floor systems, due to its favorable performance, cost efficiency, safety, and sustainability attributes. However, the structural and economic advantages of CFS floor systems can be undermined by vibration serviceability challenges if not appropriately addressed in the design phase. Furthermore, utility holes, such as slotted or circular openings in the web of CFS joists, are commonly introduced to accommodate piping, plumbing, or electrical wiring. These holes, while functional, may also affect the serviceability of the floor system by altering its dynamic response and structural integrity. Existing design methodologies for calculating the dynamic properties of floor systems have been primarily developed for light-frame CFS, structural steel, and concrete floor systems. The applicability of these methods to I-shaped CFS joists, particularly those with utility holes, remains unexplored. Furthermore, the North American Standard for Cold-Formed Steel Structural Members (CSA-S136–16) provides design specifications for C-shaped joists at ultimate limit states but lacks provisions for I-shaped joists or edge-stiffened (lipped) holes. As such, an experimental study on CFS I-shape joists is needed to obtain experimental data to evaluate the available ultimate strength equations and serviceability design procedure when applied to such joist type with utility holes. This paper presents the experimental investigation of CFS I-shape members with web holes with edge stiffening to study the effect of stiffened holes on the serviceability and flexural strength of the member when subjected to flexural loading. Additionally, the study assessed the accuracy and applicability of existing design methods in predicting key dynamic and static performance metrics, including fundamental frequency, static deflection, and acceleration responses to walking-induced excitation. The findings contribute to the advancement of design practices for CFS floor systems, particularly those employing I-shaped members with utility holes.