Reducing Conservatism in the Design of Structural Flooring Systems: An Advanced Methodology for Predicting Footfall-Induced Vibrations in Laboratories
Michael Wesolowsky, Ph.D., P.E., Rowan Williams Davies and Irwin, Inc. (RWDI)
The design of high performance laboratories requires that structural systems must achieve increasingly stringent vibration criteria for specialized equipment. Floor vibration prediction models commonly used in North America can result in overly conservative structural systems, which require excessive quantities of construction materials. Since these materials are typically manufactured from non-renewable resources and transported over long distances, a more accurate prediction of floor vibrations is likely to result in lower construction costs for the owner and a more environmentally responsible approach, as well as an improved design that will reduce the likelihood of requiring future retrofits.
Advanced footfall vibration analyses have been developed to predict a floor system's vibration frequencies and amplitudes. Today's commonly used simple single-bay models often lead to approximate results, which may not allow the full potential of the equipment to be reached. For most applications, a three-dimensional structural finite element model of the floor should be developed in order to characterize its complex response more accurately.
Once the model has been used to generate the dynamic properties of the structural system, floor motions from occupant traffic are predicted using methodologies published by the Steel Construction Institute and Concrete Centre. These methods consider critical walking speeds and a full range of possible walking paths, which are evaluated simultaneously, unlike conventional single-bay models. Predicted vibration amplitudes are mapped onto proposed flooring layouts and compared to the applicable vibration design criteria for the space.
Use of this method allows for greater accuracy on the prediction of vibration responses for the flooring system, graphical representation of the vibration responses, and optimization of the equipment or room layout to exploit areas identified as having lower vibration responses, resulting in a better functioning space.
Biography:
Michael Wesolowsky is a senior specialist in the acoustics, noise, and vibration group at RWDI. Before joining RWDI, Dr. Wesolowsky completed his doctoral and master's degrees in the field of structural dynamics, with emphasis on hysteretic modeling of seismic isolation and damping devices for buildings and cable-stayed bridges. Dr. Wesolowsky has published and presented several research papers in journals and international conferences. Dr. Wesolowsky's primary responsibilities include the technical work and reporting related to acoustics and vibration issues, while his specialization is structural vibration, with focuses on ground-borne vibration, and pedestrian- and vehicle-induced vibrations in research laboratories, healthcare facilities, and bridges. Dr. Wesolowsky is also involved in supplementary damping system design with RWDI's structural dynamics and motion control division (motioneering) and is a licensed professional engineer registered with the Association of Professional Engineers of Ontario.