The aim is to limit the vibration levels in machines, buildings and the living environment, based on measurements and simulations.
Possible aspects of any study include measuring the vibration nuisance caused by road and railway traffic (ISO2631, DIN4150 part II and III, SBR guidelines), workers exposed to vibration nuisance (Royal Decree of 07.07.05), machine vibrations (ISO10816), dynamic stiffness of piled foundations, railway track decay, resonance of structures, dynamic properties during product developments etc.
People may be exposed to vibration nuisance from external sources, such as road traffic or heavy industrial activities going on in the immediate vicinity. This nuisance can also express itself in structural noise pollution in the low-frequency noise range. Vibration monitoring using a fully independent measuring system can carry out a vibration evaluation in situ over a period of 24 hours or longer.
The dynamic design of buildings focuses on limiting the vibration level in a building to a comfortable level, ensuring that every possible internal vibration source is adequately insulated. Structural components and dimensions are also selected so as to prevent any dynamic oscillation. The transmission of vibrations from external sources should be sufficiently disabled. Examples of this are station buildings and buildings in direct proximity to railways.
Machines comprise rotating and moving components. The cost of a machine is always compared to its production capacity. A higher productivity generates greater dynamic forces. In the dynamic design of machines, the effects of this are limited to ensure efficient, reliable operation.
The study of railway dynamics looks at the environmental nuisance caused by train traffic and designs the measures need to be taken by making adjustments to the railway tracks. Rail traffic includes trains, trams and metro systems, both over ground and underground.
Structures exposed to long-term variable dynamic stress are subject to fatigue and should have appropriate dimensions defined during the design phase. Examples of this include windmills with a highly variable wind load and a 20-year service life certificate. Water structures such as locks, weirs, flood gates etc. may be stimulated dynamically by flows of liquid.
Some architectural structures need to be checked for their resistance to earthquakes and seismic activity. The calculation is based on an excitation spectrum at foundation level and is assessed according to the modal superposition of the various relevant structural natural modes of vibration. The nuclear industry provides an example of this, where seismic requirements are defined which should be verified during the design phase.
In some sectors machines are used which are extremely sensitive to vibration impact. The vibration level in the areas where these machines are located needs to be so low that it is almost non-existent, in other words, as if the components and areas were vibration-free. To achieve this, radical structural measures need to be implemented, aimed at the structure, foundations and location of nuisance sources in the immediate vicinity. One example of an application of this is in the field of micro-electronics where lithographic machines are commonly used in submicron (cleanroom) technology. To guarantee this resolution, the vibration level at the base of the machine needs to be more or less zero. Additional attention is also required in this area in hotels, hospitals and concert halls, though with less stringent requirements.
Large-scale architectural structures or engineering works, specifically high buildings (including chimneys) and bridges with large spans, often delicate structures, demonstrate obvious dynamic behaviour, especially in combination with wind load. This should be analysed in detail.
The term “special calculations” is used to describe all the applications which use numerical simulations, based mainly on the finite element method. The applications are mainly geared towards simulating the dynamic behaviour of a structure, using this to simulate solutions. The type of calculations may include modal, harmonic, spectrum, transient and shock, linear and non-linear, plastic, fatigue etc.