The paper examines the methodologies and evaluation criteria advocated by the U.S. Federal Transit Administration (FTA) and Federal Rail Administration (FRA) used to determine whether or not a proposed alignment for a transportation project adversely impacts affected land uses, such as research & development and high-technology manufacturing. The criteria in question are applied as limits on vibration and noise at sensitive receiver locations. Both short-term construction and long-term transportation operations are typically considered, with the latter being the focus of this paper. A case study is presented of a proposed transit system that passes through four different soil zones, the operational characteristics that are required to generate a vibration level equal to the FTA/FRA advocated level of 65 VdB re: 1 micro-inch/sec, and the range of variability of the acceptability of the vibration conditions when considered in terms of third-octave bands compared to vibration criterion (VC) curves that are used as the design performance targets of vibration-sensitive facilities.
Several settings arise in the design of vibration control for sophisticated spaces in which it would be desirable to significantly increase the material damping of concrete, primarily to reduce resonant response. The paper presents an overview of a recent study addressing the various means by which concrete damping can be increased. A variety of methodologies are discussed, and the most efficacious approaches are examined in some detail. The easiest approach involves the introduction of polymer admixtures into the concrete when it is mixed. However, the resulting dynamic properties become dependent upon both temperature and frequency, and these must be considered when selecting the appropriate polymers to use. Experimental results are summarized, and some of the appropriate applications (as well as the limitations) of polymer usage are presented.
Stringent vibration requirements must be met for laboratories housing sensitive equipment for nanotechnology research. This paper provides guidance to the designer in the selection of structural systems to limit vibrations to acceptable levels. Comments are also made on site selection, building planning issues, and cost-effective solutions. The concepts proposed are illustrated with examples of the structural systems developed for nanotechnology buildings at the University of Alberta.
The paper presents a review of generic vibration criteria used for vibration-sensitive technical facilities. The paper reviews the logic behind and evolution of the Vibration Criterion (VC) curves, originally known as the "BBN" criteria, and discusses the background of a generic criterion in common usage for nanotechnology, currently denoted NIST-A. The criteria are compared with representative types of research equipment and activities.
There are several instances in the literature in which particular positions are taken regarding the nature of the floor supporting sensitive equipment such as advanced electron microscopes. Assertions are made that one methodology is better than another at reducing vibrations. However, very little experimental evidence has been provided to support those positions. This paper presents the results of an experimental in situ study of several slab configurations at a single location-the site of a nanotechnology facility that was about to be constructed at the University of Alberta. Three configurations were constructed: (a) a large solid slab of moderate thickness; (b) a smaller slab "island" of greater thickness (900 mm) surrounded by a thinner slab, both resting directly on soil and separated by a gap; and (c) another island of the same dimensions, but resting on four concrete piles. The three locations were instrumented and measurements taken allowing comparison of the performance of these configurations at attenuating ambient vibrations and vibrations due to a nearby heel-drop impulse. The ranking of the three must be based upon excitation type and frequency range of concern.
The recently built Advanced Measurement Laboratory at the National Institute of Standards and Technology (NIST) provides a great step forward for that organization with regard to its research environments. Vibration and temperature control were among the most critical concerns expressed by the researchers, and considerable attention was given to meeting their objectives. Critical laboratory environments called for vibration to be controlled to amplitudes no greater than 25nm rms displacement and 3.1 μm/s, and as much less than that as feasible. Some of the spaces required thermal stability controlled to within +/- 0.01° C. The design phase involved research projects examining ways in which those goals might best be achieved. The critical rooms met or exceeded the temperature and vibration control requirements. Some spaces were found to have displacement amplitude on the order of 10 nm, velocity amplitude of 1 μm/s, and acceleration of 19 μg, all well below the design goals, making this one of the world's finest research spaces.
Vibration analyses of advanced technology facilities typically must consider frequency as well as amplitude of vibration. A soil propagation model is proposed which will allow the use of site-specific, measurable, frequency dependent attenuation characteristics. A method is given which allows in-situ determination of those frequency- dependent properties. This approach is applied to the estimation of setback distances for various items of construction equipment at a particular site.
The paper discusses two primary areas of interest in a structural evaluation. First, in situ measurements are used to confirm the predicted structural stiffness and resonance frequencies. Second, the evaluation characterizes the manner in which vibrations are propagated through the structure. Methodologies are presented for carrying out these measurements, and typical data are given.
For many areas of acoustics, standards organizations or regulatory bodies have mandated vibration or noise criteria and defined the appropriate processing methods. No such standards exist for vibration-sensitive facilities at this time except as defined by equipment manufacturers, facility owners, and/or vibration consultants. The existing criteria from these groups differ widely in form. This paper reviews the various candidate methods offered by current technology for processing measured vibration data.
Many aspects must be considered in the design of low-vibration buildings. One major aspect is the floor supporting the vibration-sensitive equipment. This paper addresses the design of several types of floors for low-vibration environments, drawing from some of the authors'' design projects.