Measuring with light has many advantages:
  • Unequalled accuracy and reliability 
  • Measurements not influenced by electromagnetic induction 
  • No moving parts. The passive fiber itself acts as the measuring element 
  • Insensitive to corrosion, humidity, water and vibrations 
  • No drift, not even over periods of decades so no need to (re-)calibrate 
  • Measurements fully compensated for variations in temperature 
  • Very small dimensions so can be installed almost anywhere 
  • Possibility of putting a relatively large number of sensors in series, so minimum cabling
  • Withstanding the harshest possible environments suchas subsea offshore and aggressive ground water. 
  • Intrinsically safe, so suitable for installation in hazardous areas without additional measures
  • Extremely durable: the silica material of the fiber does not age.
These properties render fiber optic sensors ideally suited for Structural Health Monitoring.

SHM enables the asset owner to monitor the structural integrity of his object throughout its life span. The sensors are permanently embedded in or mounted on the structure. The great advantage of our fiber optic sensors is that they measure over a much larger reach (0,30 to 2,00 m per sensor) than traditional sensors. This provides a much more accurate and realistic basis for judging the behaviour of the structure as a whole, in particular in case of less homogenous construction materials as reinforced concrete. The system measures continuously in real-time and raises an alarm when pre-set values are reached.

Examples of SHM projects that we have executed:
  • HSL: Permanent monitoring system consisting of 378 sensors mounted at 126 locations along the Amsterdam-Paris high speed railway line. These sensors serve to monitor the vertical and lateral movement with an accuracy of 0,05 mm. The system is designed for a maintenance-free life time of 25 years.
  • Various deep water quay walls: real-time monitoring systems comprising deformation of the quay structure, erosion detection, grout anchor forces, groundwater levels and load applied on top of the quay and the area behind it.
Generally speaking the cost of a structural monitoring system does not amount to more than 1 to 2 percent of the overall capital investment. We supply fully operational SHM systems including system engineering, installation, commissioning, start-up and follow-up. If we are asked to provide data management the client can log-in on our web server.

Whenever pre-set values are reached the client automatically receives a warning or an alarm.

The system consists of a number of sensor nodes that are mounted on the object to be monitored and that communicate wirelessly with a gateway node. One single gateway node is capable of serving up to 1000 sensor nodes. The gateway node, also wirelessly, transmits the measurement data to a server. By logging into our web platform  Livesense  the owner is in a position to follow the structural behaviour of his asset at any time. Whenever a preset measurement value for any of the sensors is, the system automatically raises an alarm. The parameters that can be measured are vibration, strain, inclination, displacement, temperature and humidity.

This technology is ideally suited for static or dynamic structural monitoring of existing assets.

 Wireless structural health monitoring
    Also for the temporary monitoring of structural behaviour fiber optic sensors are the best choice because of their particular properties. A wide range of different sensors is available for measuring strain, stress, displacement, temperature, level, pressure and even groundwater pressure, also for dynamic measurements.

    If so desired we can offer to take care of the measurements and the reporting. Whenever real-time measurement is required we deliver and install the system complete with wireless data acquisition via WIFI or UMTS.

    We offer an extensive range of software packages that can be customised in accordance with the client's requirements.
    A Structural Health Monitoring System consisting of fiber optic sensors guards the structural integrity of a building 24 hours/day. It immediately raises a warning or an alarm as soon as the deformation and stresses in a critical structural element reach a predetermined level. This enables the asset operator to take the necessary measures to prevent damage and/or loss of lives.Even recent history has shown that such a monitoring system is no luxury at all. Therefor the absence of a structural monitoring system in buildings that are frequented by the public has become socially irresponsible, certainly if one considers that the cost of such a system amounts to only 1 to 2 per cent of the capital investment in the construction of the building as such.

    The SHM system is each time conceived in close consultation and agreement with the architect, structural engineer and asset owner.
    Disclaimer   Copyright 2016 by Inventec B.V.