Vibration in buildings
ISVR Consulting is often asked to measure and assess vibration in houses, offices and other premises. The vibration may be caused by nearby construction, by railway traffic, by road traffic passing over speed bumps, or by blasting. Residents may be annoyed or distressed by the vibration, and some may be concerned that the vibration could cause cosmetic or even structural damage to their properties.
Residents will feel vibration in a building, and comment on it, at far lower levels than those needed to cause structural damage. Consequently if the buildings are constructed in a way, or at a location, which does not provoke adverse comment then there is no risk to the fabric of the building, and structural damage will not occur.
People's reaction to vibration in buildings
In the UK, British Standard BS 6472:2008 covers human exposure to vibration. This standard describes how to determine the vibration dose value, VDV, from frequency-weighted vibration measurements over the frequency range 0.5 Hz to 80 Hz. The vibration dose value is used to estimate the probability of adverse comment which might be expected from people experiencing vibration in buildings. Their reaction will depend on the time of day and on the use made of the occupied space, whether residential, office or workshop.
ISVR Consulting can offer vibration measurements to BS 6472-1:2008, enabling a prediction of the likelihood of adverse comments from future occupants of the buildings. Our measurements are made in complete compliance with the standard, calculating the true VDV of vibration events. The true VDV gives considerably better predictions of people's reactions than the eVDV which is so often used.
Cosmetic damage from vibration to the fabric of a building
The severity of vibration impact on the structure of a building may be assessed using BS ISO 4866:2010 and BS 7385-2:1993. The two standards give guidance on the measurement, evaluation and assessment of vibration in buildings in the frequency range from 4 Hz to 250 Hz. The risk of vibration-induced damage is dependent on the magnitude, the frequency characteristics and the overall duration of the vibration input, as well as the type of construction of the building.
Some examples of recent projects
Vibration from construction plant
A recent project was initiated by the construction of a dual carriageway road close to a number of residential properties. There were concerns that the use of a vibrating roller for compacting the ground could cause structural damage to a nearby property.
ISVR Consulting measured the maximum values of all three orthogonal component particle velocities at the complainant’s house to assess whether they exceeded the guideline values in BS 7385-2. All three components were measured simultaneously on the concrete floor of the house as shown in the photograph.
Measurements were also carried out at the foundation of the building or at a point low on the main load-bearing external wall of the ground floor.
The assessment, using BS 7385-2, showed that there was very little risk of damage, even if the roller were operating continuously at its maximum vibration setting.
Vibration from railways
Another recent project showed that structural damage to a new build has been caused directly by the vibration from heavy goods trains. This has highlighted the need for vibration measurements to be made before planning permission is granted on other similar sites.
In other work, ground-borne noise predictions due to the construction and operation of metro-rail systems have been made in collaboration with the ISVR Dynamics Group.
BS 6472-1:2008. Guide to evaluation of human exposure to vibration in buildings - Part 1: Vibration sources other than blasting. BSI London.
BS ISO 4866:2010. Mechanical vibration and shock. Vibration of fixed structures. Guidelines for the measurement of vibrations and evaluation of their effects on structures. BSI London. (Supersedes BS 7385-1;1990 and ISO 4866:1990)
BS 7385-2:1993. Evaluation and measurement for vibration in buildings. Part 2 - Guide to damage levels from groundborne vibration. BSI London.