Fatigue is often a top concern for bridge and other structural owners and engineers. It has been estimated that 90% of the structure failure is due to fatigue.

Resensys Wireless Strain Gauge SenSpot™ sensor installed on bridges for fatigue analysis with the rainflow counting methodology

Resensys proposes breakthrough wireless tools for precise long-term strain monitoring and fatigue analysis with a wide variety of cost-effective benefits:
    · Wireless Strain Gauges: No wiring, minimal lane closure for installation.
   · Sensors with 10+ Years of Battery Life: No need for battery replacement, maintenance or calibration in the field.
    · Easy Installation: Self-adhesive(e.g. on steel) or flange-mount(e.g. on concrete).
    · Quick Testing: Can be installed for short-term testing (e.g., for load rating), easy to remove and reuse on other structures.
    · Long-term monitoring: Designed to be used for long-term monitoring (e.g., several years).
    · Small Size and Light weight
    · Being Suitable for Different Kinds of Materials: Can be used on steel, concrete, timber and composites.
   · Rugged and Weatherproof Devices:  Can operate in rain snow, ice, high humidity and extreme weather (-40°C to +65°C or -40°F to +150°F).

This system reduces the cost and time for installation, and makes Resensys solutions a cost-effective way for owners / authorities to get the quality data they need for fatigue analysis. A unique capability of Resensys wireless strain gauge SenSpot™ sensor is to measure at high sampling rate (typically 20-100 samples per second), while still providing 10 years of battery life. The high sampling rate enables the system to detect all loading instances, count loading cycles and perform fatigue analysis such as rainflow counting.

Strain-Triggered-Burst (high-strain events) measurements of an installed Wireless Strain Gauge SenSpot™ on a bridge

Rainflow counting analysis with Resensys SenScope™ software

A typical strain monitoring system includes the following components:
    • Wireless Strain Gauge SenSpot™ sensors are attached to the fatigue prone members of a structure. The number of gauges required per structure is usually dependent on the design, existing issues on members and fatigue analysis needs.
    • SeniMax™ gateway is a wireless data logger that is connected to the internet through cellular or satellite networks; it wirelessly collects data from SenSpot™ sensors at the site and sends them to a cloud server (one SeniMax can cover as many as 100 SenSpot™ sensors within its wireless communication range).
   • SenScope™ software for data analysis and visualization, data export, automated alert management, thermal analysis, and fatigue analysis. For fatigue analysis, Resensys SenScope has a built in computational module for rainflow counting.

The figure below shows a picture of a practical Resensys Structural Health Monitoring (SHM) system, which can be used for the fatigue analysis of a bridge or other structures based on rainflow methodology.