Reducing Structural Materials Through Space Planning and Optimized Placement of Vibration-Sensitive Equipment

Julia Graham, M.A.Sc., RWDI, Inc.

Recent advances in construction materials and techniques have led to increasingly lightweight and flexible floors. Lightweight floors are desirable from an economic and sustainability perspective, as they require smaller quantities of construction materials. At the same time, high-performance laboratories are requiring structural systems that provide platforms for equipment with increasingly stringent vibration criteria. As a result, floor vibration considerations can often govern the structural design of floors in sensitive laboratory spaces. To reduce the quantity of construction material required for sensitive laboratories, as well as costly redesigns, the effect of the architectural layout on vibration produced through pedestrian footfalls should be considered at the early stages of design. When laboratories are located on elevated floors, mechanical and pedestrian-induced footfall impacts are typically the predominant sources of vibration. The focus of this discussion will be footfall-induced vibration.

Recent advances in footfall vibration prediction methodologies have highlighted the importance of the architectural layout when assessing the vibration performance. Designers should consider the placement of sensitive equipment with respect to vibration sources to prevent the need for costly and environmentally objectionable mitigation. Long, open corridors can be a significant source of vibration especially when placed along the center of bays. Locating sensitive equipment at slab-on-grade locations, far from corridors or close to shear walls and columns can significantly reduce the need for mitigation.

In this presentation, case studies are used to illustrate the importance of strategic architectural planning for the purpose of vibration control. The case study buildings are new and retrofitted research facilities and other structures housing sensitive spaces. For each floor studied, three structural designs are compared: 1) the design provided by the structural engineer in absence of vibration considerations, 2) the design required to satisfy the specific vibration criteria based on the original architectural layout, and 3) the design required to satisfy the specific vibration criteria based on a layout that has been altered to provide better vibration performance. The quantities of construction material required for each structural design are presented. Using these results, the savings realized by employing efficient layouts are quantified in terms of the tonnages and dollar values of the additional steel and concrete required to satisfy the vibration criteria.

Biography:

Julia Graham is a Project Scientist in the Acoustics, Noise and Vibration Group at RWDI Inc. Before joining RWDI, Julia achieved her Masters degree in the field of Structural Dynamics. As a member of the ANV team, Julia's primary responsibilities include performing technical analyses and reporting related to acoustics and vibration issues. She has worked on projects in Canada, the United States, China, the Caribbean and the Middle East. She has developed numerous finite element models to predict vibration levels in structures and regularly travels to research facilities and other vibration-sensitive buildings to take vibration measurements. Julia is also involved in developing and delivering educational seminars on vibration-related topics for architects and engineers.

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