Dynamic Characterization and Vibration Serviceability Evaluation of All-Steel Modular Floor Systems

Abstract Lightweight steel floor systems are increasingly being adopted in modern buildings, where vibration serviceability under human-induced loading often governs structural design. This study presents an experimental–numerical investigation to clarify the dynamic mechanisms and serviceability performance of a nontraditional all-steel modular floor system. Two floor modules with identical geometry but different beam and plate sizes were tested to quantify the influence of mass and stiffness on dynamic response. Each module was evaluated in both bare-steel and raised access floor (RAF) configurations, resulting in four experimental cases. Experimental modal analysis was performed using an electrodynamic shaker and a high-resolution measurement grid to identify natural frequencies, damping ratios, and governing mode shapes. Results demonstrate that the low-frequency response of the all-steel modules is dominated by plate-controlled and coupled plate–beam vibration modes and that the primary beam-bending mode does not necessarily occur as the fundamental frequency, in contrast to common assumptions for conventional composite floor systems. Measured damping ratios were low for bare modules, indicating heightened sensitivity to vibration serviceability, while installation of the RAF consistently increased damping and produced mode-dependent shifts in natural frequencies. Calibrated finite-element models were developed to reproduce the experimental modal characteristics and provide a validated framework for evaluating walking-induced vibration response. In addition, the modeling approach explicitly captures plate–beam interaction mechanisms that govern the response of lightweight all-steel floor systems. The primary contribution of this work is the combined experimental characterization and validated modeling of an all-steel modular floor concept, together with the identification of the governing vibration mechanisms and the influence of architectural floor layers on damping behavior. These findings provide new insights into the dynamic behavior and serviceability performance of all-steel floor systems and offer a foundation for evaluating and designing nontraditional modular floor systems where traditional composite floor assumptions may not be applicable.