Vibration: Environmental: Building Damage

Firstly it is true to say that people do not normally experience vibration in their homes; therefore, when there is a new source of vibration, occupants are disturbed and assume that damage is being caused. Occupants tend to examine the property for signs of damage and will probably find cracking which they had not noticed previously; it seems natural to attribute the "new" cracking to the new vibration source; however, given that occupants don’t normally look for cracks, it may simply be that the cracks preceded the new vibration source.

Buildings are fairly resilient to ground-borne vibration; therefore real damage to buildings is rare, although possible; cosmetic damage such as cracking is much more likely than damage to load bearing elements.

BS 7385: Part 2: 1993 "Evaluation and measurement for vibration in buildings" gives guidance on the levels of vibration above which building structures could be damaged. The standard states that there is a major difference between the sensitivity of people in feeling vibration and the onset of levels of vibration which damage the structure. Furthermore it states that cracking commonly occurs in buildings whether they are exposed to vibration or not.

For residential buildings, the standard states that for cosmetic damage (cracking in plaster work etc.) to occur, for a vibration frequency of 4Hz, a peak particle velocity of some 15 mm/s is necessary. This rises to 20 mm/sec at 15hz, and thereafter the limit rises to 50 mm/s at 40 Hz and above. This limit applies to the resultant of the vibration levels in the three mutually perpendicular axes. Limits for structural damage are naturally higher than for cosmetic damage, but are not stated in the Standard.

<<< Back to Environmental Introduction

On to Disturbance >>>