Development of an innovative cold-formed steel-plywood composite floor system using epoxy-resin adhesive for residential buildings

This study aimed to develop innovative lightweight composite flooring system consisting of cold-formed steel (CFS) and plywood with epoxy-resin adhesive connections. During the investigation, four composite floor panels were fabricated by bonding C75.100 CFS beams with 12 mm thick Meranti plywood on bottom flange and 18 mm thick MerantiSengon plywood on top flange using epoxy-resin adhesive. These panels have dimensions of 900 mm by 2800 mm, with a thickness of 105 mm, and were subjected to vibration, bending, and creep tests. In addition, evaluation of the floor system was conducted to determine its compliance with the required ultimate and serviceability limit states, based on typical residential building design loads. Numerical analysis were developed to validate the vibration and bending test results. The experimental results for the floor system showed natural frequency of 25.65 Hz, moment capacity of 18.60 kNm, flexural stiffness of 369.96 kNm2, and 90th-day creep factor of 0.15. Numerical analysis differences compared to experimental results were in acceptable ranges, including 0.4–10.6% for moment capacity, 3.3–5.5% for flexural stiffness, and 6.2–7.4% for natural frequency. Following this discussion, safety factor of 6.2 was obtained from ultimate limit state evaluation. Total deflection, including 0.24 creep factor for 50-year service life, was 4.88 mm, less than 1/240 of floor span limit. The natural frequency of 25.65 Hz exceeded the minimum comfort requirement of 8-9 Hz. The results of the investigation showed that this CFS-plywood composite floor system was lightweight, safe, and suitable for residential buildings.