Determination of equivalent rigidities of cold-formed steel floor systems for vibration analysis, Part II: evaluation of the fundamental frequency

Structural properties of cold-formed steel (CFS) floor systems are essential for evaluating vibration performance of the floor systems. Comprehensive analytical and experimental studies on equivalent rigidities of CFS floor systems for vibration analysis based on orthotropic plate model are presented in this and the companion paper. In Part I of the companion papers, the equivalent rigidities were determined by using Rayleigh's method with considerations of the rotational restraints of joist ends and various configurations of transverse elements. Rotational fixity factors and restraint coefficients were introduced to characterize the effect of the rotational restraints. A joist contribution factor was defined to suitably consider the stiffness contribution of joists for a vibration mode. The Part II of the companion papers presents herein the development of design equations to predict the fundamental frequency of CFS floor systems for vibration serviceability evaluation. Simplified equations were proposed for evaluating the restraint coefficients. More importantly, rotational fixity factors for different CFS framings were investigated based on experimental data. Finally, the predicted results from the proposed method were compared with test results and other methods, and the applicability of the developed equivalent rigidities was assessed.