As a result, structural engineers must use their experience and judgment in developing appropriate vibration performance criteria and damping measures. There are no code-specified criteria for the design of floor framing to control vibrations. While this vibration is typically not perceptible on a physical level, the ramifications to sensitive laboratory equipment can be significant. If the forcing-function frequency caused by walking is close to the natural frequency of the floor framing, nuisance vibration will likely occur. Typical floor systems fall in the frequency range of 3 to 8 hertz (Hz). Each step creates a forcing function, and the walking pace applies the force at a particular rhythm or frequency.Įach floor structure has a natural frequency that is a function of its span, stiffness, and mass. Although these sources can certainly cause problems, the primary source of nuisance vibrations in sensitive laboratory equipment is generally as close as the opposite side of the work partition-colleagues simply walking down the corridor to and from their offices, going about their daily routine. Many administrators and technicians assume that roadway traffic and mechanical systems are the primary sources of floor vibrations. This article presents a straightforward overview of laboratory floor vibrations and suggests some strategies to improve the behavior of most laboratory building structures. With thoughtful design, the engineer can create a floor system that properly damps vibrations for sensitive equipment in an affordable and functionally flexible structure. If the structural engineer is proactive and invited to assist in the early stages of design, before the module is established, he or she can exert a powerful influence on the floor system’s vibration characteristics. The good news is that proper architectural planning and structural design can provide floor framing that is capable of mitigating vibration.įloor vibration criteria for equipment used in the production of integrated circuits.
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Improperly designed, these modules can exacerbate vibration problems. To provide adequate functional flexibility, laboratory facilities are usually designed in modules. Many medical laboratory facilities are designed as shell spaces to house future research programs that obtain grant funding well downstream of the building design process.
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Even very slight movements, imperceptible to a person sitting still, can disrupt sensitive laboratory equipment. The culprit, of course, is a structural system that ineffectively deals with the vibrations caused in virtually every building. The optical precision balance waves slightly rather than giving a steady and accurate measurement. Too often, a laboratory technician views a distorted specimen through a 400 × microscope. Not from earthquakes or tsunamis but from a source much more common and insidious: people going about their daily routines. There is a “whole lotta shakin’ goin’ on” in laboratories across America.