The vibrations which are caused by the source of the shock may spread throughout the building structure: they are perceived as noticeable vibrations, they can spread as secondary airborne sound, and when the worst comes to the worst, they can damage the building structure. What is more, the function of machines and measuring equipment in the building may be impaired.
The objectives of the vibration isolation of buildings are:
- health protection
- the protection of the building fabric
- the protection of the technical equipment inside the building
Shock is the common term for mechanical vibrations of solid bodies with a potentially damaging or disturbing effect.
Structure-borne sound refers to vibrations which, contrary to airborne sound, continue through a solid medium. Vibrations in liquids are called liquid sound.
The transmission path of vibrations or of shock may include a change of media.
The protection of buildings against vibrations can be achieved through different measures:
- Vibration-reducing measures at the place of the emission, e.g. a mass-spring system in a railway track.
- Interruption of the transmission of the vibration in the transmission area, e.g. through a below-ground slotted wall or by shielding the basement walls.
- Shock and structure-borne sound decoupling at the place of immission, underneath the building foundations and at the exterior side of the basement walls at the earliest. This is the measure most commonly used.
Most decoupling measures are taken at the building foundations and are called resilient bedding of buildings. Railway tracks are one of the most frequent causes of emission. Therefore the majority of the measures apply to resilient bedding of buildings for interfering frequencies between 25 and 100 Hz. Vibrations in this frequency range are critical, as they can lead to building component resonances and thus to secondary sound effects.
Consequently, the resilient bedding of buildings is intended to reduce the transmission of vibrations in the structure of the building with the help of the isolating material and by taking complex impact factors into account. Lowering the level to between 10 to 25 dB, depending on the frequency, is no problem at all with Regupol® and Regufoam®.