The standard DIN 4150-3 may be applied for structures which do not need specific design requirements with reference to dynamic load. The standard defines the values which must be met to avoid damage and impact on structures.
Vibrations are divided into short-term vibrations, which do not occur frequently enough to cause fatigue and do not cause resonance in the assessed structures. Long-term vibrations, on the other hand, are all vibration types which cannot be classified as short-term vibrations.
Vibration velocity values used in the impact assessment of short-term vibrations on structures are divided into three categories, depending on the type of the assessed structure [DIN 4150-3]. Each category features a curve illustrating the permissible vibration velocity limit. The analysis of the measured velocity and the prevailing frequency allows one to obtain a clear picture of the impact of vibrations on the tested structure. The first category and the corresponding Line 1 refers to buildings used for commercial purposes, industrial buildings etc. Dwellings and buildings of similar design and/or occupancy fall into the second category. The third category includes structures that, because of their particular sensitivity to vibration, cannot be classified under lines 1 and 2.
In order to meet American standards (IEST) that uses 1/3 octave bands curves (VC Vibration Criterion curves) expressed in RMS vibration velocity, building vibration meters use 1/3 octaves. The 1/3 octave band method compares RMS results in each band to the limit curve. So in fact the whole spectrum is used for comparison unlike in FFT method where the point (PPV, DF) is positioned versus the curve.