Vibration Serviceability Assessment of a Steel Modular Floor System

A new modular steel floor system, named FastFloor, is proposed for commercial buildings. The system is conceptualized to be prefabricated at the shop and ready to be installed on a previously erected skeleton frame structure consisting of girders and columns or connected to core shear walls. The system configuration aims to increase the speed of design, fabrication, and erection of a steel project by eliminating concrete pouring and curing times. Other advantages include reducing the weight of the building and its carbon footprint. Several module configurations were considered and evaluated based on a series of interviews with experts in steel fabrication and erection engineering. The selection relied not only on addressing the issues related to fabrication, transportation, and erection but also on satisfying floor vibrations, as it was determined to be the governing limit state of the plate thickness, section sizes, and beam spacing due to the presence of an unstiffened bare plate acting as a slab. Observations were performed regarding fabrication sequence and transportation on the chosen configuration. The dynamic properties of the module are particularly important because DG11 was developed for composite concrete-steel floor systems, and its applicability to all steel-floor systems needs to be evaluated. In parallel, a vibration testing program was conducted to determine the dynamic properties of the module, including natural frequencies and mode shapes. Lastly, the acceptability of the modular system for floor vibrations was evaluated by both a calculation method and a modeling approach. The analysis results suggest that the module will not satisfy floor vibrations criteria, but a modified module with added stiffeners is shown to be acceptable. Upcoming tests, by others, on specimens with a raised access floor will be necessary to refine the predictions and determine if the stiffeners are actually required.