Road or rail traffic, demolition, compaction, drilling, industrial machinery or natural phenomena: buildings and structures are regularly subjected to vibrations.
These stresses do not systematically cause damage. Their impact depends on their intensity, frequency, duration and repetition, but also on the condition of the structure, its foundations and the surrounding soil. An acceptable level for a recent building can thus become problematic for an old structure, weakened or housing sensitive equipment.
What is vibrational measurement?
Vibrational measurement involves recording the movements transmitted to the ground, to a building or to a structure following an external disturbance. This action can be punctual, repeated or continuous.
Generally carried out along three orthogonal axes, it allows for the measurement of:
• the acceleration, in mm/s² or mg;
• the particle velocity and its maximum value, called PPV, expressed in mm/s;
• the dominant frequency, expressed in hertz;
• the duration and the repetitiveness of events.
Intensity alone is not enough to assess the impact of a vibration. Its frequency is also crucial: when it approaches the natural frequency of a structure, low frequencies, the movements can be amplified and cause damage.
Why monitor vibrations?
On a construction site, vibration measurement helps protect neighbouring buildings and ensures that the work remains compatible with the thresholds defined for the project. In case of exceedance, the power, frequency or method of execution can be quickly adjusted.
Timestamped measurements also allow each event to be linked to the site log, to identify the equipment or operation concerned, and to have objective data in case of a claim.
On a structure in operation, changes in frequencies, amplitudes or vibration speed can reveal a modification in dynamic behaviour, a loss of stiffness or an unusual response under comparable loading.
Vibration measurement does not replace structural expertise. It complements it with objective data and allows for monitoring the evolution of the structure between two inspections.
In what cases should monitoring be implemented?
Vibration monitoring is particularly suitable for:
• demolition, compaction, piling, drilling or earthworks;
• neighbouring buildings of a construction site;
• historical monuments and old masonry;
• bridges, walkways and structures;
• tunnels and railway infrastructure;
• to industrial sites and sensitive equipment.
Reliable monitoring begins with a precise definition of the objective and, when possible, by establishing a baseline before the work begins. Sensors should then be securely fixed to representative points, such as foundations, a load-bearing wall, an exposed façade, or a critical structural element.
What standards to apply?
There is no universal threshold applicable to all structures. The values depend on the country, the type of building, its condition, the measured frequency, and the nature of the work. In France, the circular of 23 July 1986 is also used as a technical reference in certain contexts, particularly for mechanical vibrations emitted into the environment by classified installations.
Several references can be used such as:
• the Circular 86, in France, for the assessment of mechanical vibrations emitted into the environment;
• the IN 1226, mainly for work near railway infrastructure;
• the BS 7385, in the United Kingdom, to assess the risk of damage to buildings;
• the SN 640 312a, in Switzerland, depending on the sensitivity of the construction and the type of source.
• The DIN4150-3, widely used German technical standard in Europe for assessing the effects of vibrations on buildings.
Thresholds must always be defined according to the project context and the requirements of the responsible professionals.
The DELTA V for connected monitoring
With the DELTA V, FEELBAT completes its range of connected sensors dedicated to structural and geotechnical monitoring.
The references Circular 86, IN 1226, BS 7385, SN 640 312a and DIN4150-3 are directly integrated into the FEELBAT mobile application. The user can thus select the appropriate standard, facilitate the reading of results, and more easily set their alert thresholds.
Measurements can be accessed remotely, archived, and associated with custom alerts. Vibration monitoring can also be cross-referenced with the monitoring of cracks, inclinations, deformations, piezometric levels, and environmental conditions.
This multiparameter approach allows each event to be placed in its context and provides a more complete view of the structure's behaviour.
In Brief
Vibration measurement is not just about checking if a threshold has been exceeded. It helps to understand how a load is generated, how it propagates, and how the structure responds.
On a construction site, it helps to adapt execution methods and protect nearby buildings. On an operational structure, it complements inspections and contributes to monitoring the evolution of its dynamic behaviour. In an industrial environment, it also protects equipment and business continuity.
Associated with continuous monitoring, alerts, and context-appropriate analysis, vibration measurement becomes a true tool for prevention, traceability, and decision support.