Site Survey

MagneticSpectrum

Science buildings often are high-risk projects because:

  • The end customer does not often order a new science building.
  • The building contractor team usually only gets to build a specific kind of science building once.
  • The consultant usually has limited knowledge about what is required for scientific machines to work well and may not have participated in this type of project before.

As the usefulness of the science building stands or falls with its performance, our advice is to use a risk based project management philosophy when constructing science buildings.

Scientific machines usually have so-called machine criteria that specify the environment required for maximum performance. If you do not yet know what type of machinery your building requires, there are generic vibration criteria that can be used.

If there are multiple possible locations for the scientific building, a site survey should be made. To make sure that you truly capture the site character, many measurements should be made at a proposed building site over time.

For a site survey of sensitive scientific machinery, you should examine:

  • Noise (pressure)  – strength and spectrum.
    If your machine uses air springs, noise (pressure) can be rather important, as the air spring lift force depends on relative pressure.
  • Vibration – depending on the type of machine, it can be affected by either acceleration or by displacement (or both).
  • Magnetic field variation in the case that your machine is affected by electromagnetic fields.

 

In brief, things to consider in a scientific building project are:

  • Primary noise (pressure) sources are:
    • A ventilation system in a clean room.
    • People’s voices – particularly when they are forced to shout in environments with high background noise.
    • Doors, sluices, and machines with vacuum chambers that open, pneumatic equipment, etc.
    • Air frame noise from airplanes, helicopters etc.
    • Primary vibration sources are:
      • People – in particular when walking on building slabs.
        • Walking down a stairway is usually a more severe than walking up a stairway.
        • Slab stiffness matters, as does the specific location of sensitive equipment. Positions near sturdy walls and columns are often better than any place on the slab.
  • Heavy traffic, e.g. trains, trucks, trams and similar.
  • Magnetic field variation:
    • Large moving iron objects, e.g. elevators, trucks (if there is a load bay nearby).
    • Ground loops.
    • Electric cables with high current/voltage.
    • Soil properties may matter.
      • Rayleigh waves can be handled, but if Love waves are important, you may face a challenge (see the FTF nanolab paper).
      • Make sure that you measure triaxial vibration during the site survey, unless there is documented knowledge this is not required.
      • People – in particular when walking on building slabs.

 

More information on Low Vibration Building can be found here: Link, Link

 

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