Structural monitoring and durability

Structural sensors are used to monitor structural movements, deformations, stresses and strains in buildings, engineered structures, civil engineering structures and historic monuments.

The wide range of sensors available means that structural monitoring solutions can be tailored to specific challenges and budgets.

One of their main applications involves the installation of structural sensors where work is carried out on, or near the structure, to ensure that its integrity is not compromised.

They are also used for long-term structural monitoring to track the health of the structure over time, and tailor appropriate maintenance solutions.

They support the process of structure life cycle management within a wider sustainability policy.

Installing structural sensors allows you to:

Achieve short- or long-term monitoring of structural movement and deformation
Limit interruptions to the operation of a structure following a climate event or accident
Analyse and understand the behaviour of a structure
Extend the service life of structures and optimise their maintenance costs
Manage sustainability and resilience of assets

Some typical applications for structural sensors:

Nearby construction work
Renovation, upgrading, extension, underpinning project
The appearance of structural issues, such as cracks
Load increases (greater bridge traffic volumes, a change of machine type in a production plant, a change in the type of warehouse use, creation of additional floors in a building, etc.)

In the context of long-term monitoring, the measurements produced by these sensors enable:

Health monitoring of the structure as the basis for changes to maintenance specifications
An extended lifespan for the structure concerned
Verification of structural safety and usability following an earthquake, climate event, fire or accident
Verification of structural behaviour following an extreme climate event for which the structure was not initially designed
Optimisation of designs for similar new structures (thereby reducing their ecological footprint)

Cyclops

Automated 3D topographic monitoring of structures and surfaces

Cyclops™ is a proven geodetic solution for continuous automated 3D monitoring of structures and surfaces:

It provides remote 3D movement measurement with sub-millimetric accuracy
It also enables theodolites to be grouped within a globally unstable environment to deliver guaranteed nominal accuracy

Find out more about our Cyclops solution

4DShape

3D continuous linear inclinometer

4DShape is an all-in-one solution that uses a flexible chain of 3D inclinometers to monitor the relative movement of vertical, horizontal or converging profiles in soils and on structures.

Find out more about our 4DShape solution

4DBloc

GNSS-based deformation sensor

4DBloc is a GNSS-based sensor that provides real-time monitoring of ground surfaces and built structures.

4DBloc was developed and tested in cooperation with the French National Institute of Geographic and Forest Information (IGN) with the shared aim of creating a GNSS-based position measurement system that is robust, simple, cost-effective and accurate.

Find out more about our 4DBloc sensor

4DVib

Remote inspection of structures

4DVib uses interferometric radar technology to provide high-frequency remote measurement of structural displacement to generate:

High-frequency structural displacement measurements
Vibration measurements
Natural frequency data

Find out more about our 4DVib solution

Inclination measurements

Tiltmeters or inclinometers

Tiltmeters or inclination sensors, also sometimes called electronivelles or inclinometers, measure variations in the inclination of their support with very high accuracy: typically of the order of 0.1 mm/m or 0.005 degrees.

These sensors can be used to monitor the tilting of a wall or post, as well as settlement. In the latter case, they are usually installed in a horizontal position. Assuming the support is rigid, vertical or horizontal deformations can be calculated by integrating the variation in inclination over distance.

Themis are an improved version of these sensors.

Thémis

Inclinometer sensors

A well-known limitation of tiltmeters is their potential sensitivity to temperature. Often the MEMS (Micro Electro Mechanical Sensor) chip, which reads the angular variation, is impacted by temperature variations and can give incorrect angular indications.

The construction of the sensor can also lead to such sensitivity. Sixense offers Themis sensors, which are individually temperature-calibrated in a climatic chamber. The effect of temperature variations on the sensor is thus corrected at source, for more reliable, accurate and useful measurements.

Displacement measurements

Displacement sensors or crackmeters

Displacement sensors (crackmeters) enable precise control (0.1 mm to 0.01 mm) of relative displacement between 2 parts of a structure. They can be used to monitor the evolution of crack or joint opening, for example.

Fissurologgers combine a fissurometer and a data acquisition system.

We can also offer long-base displacement sensors, with wire or rod, to measure movements between distant parts: unstable blocks in a cliff, or between 2 walls of a church, for example.

Strain measurements

Strain gauges

Measuring the evolution of stresses in a structure is a common engineering need. We offer a wide range of solutions:

Gauges welded or screwed or bonded to the surface of metal, concrete or glass, or embedded in concrete, or clamped or welded to a cable
Sensor dimensions from a few millimeters to 1 meter
Electrical measurement technology (Wheatstone bridge), vibrating string or fiber optics (most often Bragg, FBG)
Static measurements (typically one measurement per hour, for example) or dynamic measurements (hundreds of measurements per second, to measure temporary material states)

The name “strain gage” is a bit of a misnomer, since we’re measuring micro-strain, which can then be transformed into stress, provided we know the material’s Young’s modulus.

Another French name for the same sensor is “extensomètre à corde vibrante”.

It is also possible to calculate the fatigue of certain materials from the number of high-frequency stress cycles.

Finally, it’s important to remember that sensors only measure stress variations relative to the day of installation. Other techniques exist for measuring historical stresses, such as the Slotstress cylinder, the central hole method, etc.

Load measurements

Load cells

Load cells directly measure forces in kN (kiloNewton).

They are typically installed between two structural elements, for example between two tunnel hangers, at the end of a strut, under a jack to measure the forces applied to a foundation during a loading test, or at the head of a nail or tie-rod.

It should be noted that the measurement accuracy of these transducers is strongly influenced by the inevitable alignment errors on site. To reduce these errors, we recommend the use of rigid plates on either side of the cells. Also, as with all transducers, care should be taken when selecting the full scale of the transducer: low scale transducers are not very accurate.

Vibration monitoring

A complete range of services for vibration monitoring of construction sites and sensitive structures

As part of our vibration monitoring missions related to construction sites, Sixense offers the installation of instruments adapted to the calculation and monitoring of indicators prescribed by current standards (e.g., ISO 14837-31 or DIN 45669-1).

Sixense also offers customized temporary or permanent instrumentation systems to monitor and analyze vibrations on sensitive structures (modal analysis, recording of rare events such as earthquakes, or shock detection).

Temperature measurements

Weather stations

Meteorological measurements include conventional or ultrasonic measurements, wind speed and direction, temperature, atmospheric pressure, humidity, etc.

Temperature is a major source of stress influence in structures. It is possible to measure surface temperatures with sensors bonded to structures, but also in-depth temperatures, particularly in concrete, with sensors inserted at different depths in the structure. The sensors are fairly simple and are also widely used in industry, with PT100, PT1000, thermistor, thermistor technologies, etc.
We also use one of the properties of optical fibers to measure temperature along a fiber, with Raman technology.

Syracuse

Monitoring and anticipating corrosion risks

Syracuse is a system for the continuous measurement and prediction of corrosion risks in reinforced concrete structures. Developed by the corrosion department of Nantes University and Sixense Monitoring, Syracuse evaluates and monitors the actual state of reinforced concrete infrastructures in service (harbour quays, bridges, offshore wind farm structures), and helps anticipate the work to be scheduled.

Syracuse is the only system on the market that enables continuous monitoring of corrosion risk, by monitoring the progression of chloride ions within the concrete and incorporating a major notion of long-term prediction of this evolution. In this way, the client can manage the corrosion issue with peace of mind, with the certainty of not missing out on serious cases with potentially significant consequences, and without incurring unnecessary costs on healthy structures.

Intelligent segments

Patented device for monitoring the stress state of a concrete element

Intelligent segments incorporate an autonomous stress monitoring system. The system is installed from the manufacturing stage of the element and is immediately operational, allowing monitoring of stress variations from concrete hardening to segment installation and throughout the entire life cycle of the segment.

Find out more about our intelligent segments solution.

Anti-lightning protection

Lightning represents a major risk to electronic structures and equipment. Its direct impacts, as well as induced overvoltages, can cause significant damage: destruction of components, service interruptions, even property damage.

To meet these challenges, Sixense offers a lightning risk monitoring solution based on two complementary sensors: one capable of detecting thunderstorm activity within a 30 km radius, the other designed to count impacts on lightning conductors. This approach makes it possible to monitor a site’s exposure to thunderstorms in real time, and to trigger appropriate preventive or maintenance actions. Where relevant, structural measures can also be implemented, such as monitoring stresses in the collector lines.

In addition, Sixense has developed a wide range of lightning protection products designed to protect its sensors and measurement systems against the destructive effects of electrical discharges, guaranteeing measurement continuity and data reliability, even in highly exposed environments.

The advantages of our instrumentation solutions

Cutting-edge expertise

developed out of more than 20 years of experience and in-house development

The availability of dedicated local teams

as a result of our extensive network

A turnkey service

from installation to provision of pre-processed data in an accessible webspace

The geotechnical and structural expertise

needed to interpret measurements in ways that meet your requirements more accurately

Data quality control and monitoring

driven by proactive maintenance to ensure that measurements are accurate and practically useful