Vibration performance of cold-formed steel and plywood composite floors – Experimental studies

Cold-formed steel and timber composite floors are lightweight structures with relatively high stiffness, allowing for longer spans. Consequently, they demonstrate inherent characteristics of reduced fundamental natural frequency and damping compared to conventional counterparts, rendering them prone to vibrations induced by human activities such as walking and dancing. This study delves into the dynamic performance of such lightweight floors, comprising cold-formed steel joists and plywood panels. Employing modal testing alongside deflection assessments, twelve full-scale composite floors were subjected to analysis to elucidate their dynamic attributes, including natural frequencies, mode shapes, and flexural stiffness. The findings unveiled that composite floors constructed with cold-formed steel and plywood, featuring a span length of 4.50 m, manifested fundamental natural frequencies exceeding 8 Hz. Furthermore, assessments of flexural stiffness derived from vibration and deflection tests suggested a robust composite action, with minimal slip observed at the interface between plywood panels and cold-formed steel joists.