Small Autonomous Devices in civil Engineering. Uses and requirements. By Peter H. Møller Rambøll

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Christina Frederiksen
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1 Small Autonomous Devices in civil Engineering Uses and requirements By Peter H. Møller Rambøll

2 BACKGROUND My Background 20+ years within evaluation of condition and renovation of concrete structures Last 6 years: focus on concrete infrastructures (bridges, tunnels) Monitering, hvad har vi gjort, og hvad fik vi ud 2

3 FOCUS AREA OF THE PRESENTATION The use of sensors for systematic maintenance of infrastructure constructions Direct costs in Denmark: >20 mill / year + Traffic restrictions (indirect cost) Monitering, hvad har vi gjort, og hvad fik vi ud 3

4 Monitoring not covered in this presentation Monitoring of overall structural behavior (stiffness) Monitoring of critical failure Monitering, hvad har vi gjort, og hvad fik vi ud

5 SYSTEMATIC MAINTENANCE STRATEGY Condition Renovation cost Cost Time Systematic maintenance based on: Condition of the structure Cost for renovation/prevention Net Present Value calculation First detailed evaluation of condition after years Monitering, hvad har vi gjort, og hvad fik vi ud 5

6 WHY ARE THE USE OF SENSORS SO LIMITED? Very effective surface based methods for evaluation of condition Sensors for evaluation of condition more than 20 years old New structures designed for hands on inspection 6Dansk betonforening

7 Areas suited for use of sensors Areas with difficult access Outside of tunnels Condition of protective membranes Monitering, hvad har vi gjort, og hvad fik vi ud 7

8 WHY ARE THE USE OF SENSORS SO LIMITED? The areas can be inspected at high costs but costs for sensors are even higher 8Dansk betonforening

9 WHY ARE MONITORING BY SENSORS EXPENSIVE? Cables Sensor Delay of concrete casting Early investment (NPV-method: 30 years before needed: x 3 50 years before needed: x 9 Expert for field measurements Often more than 10 m cables 9Dansk betonforening

10 REDUCTION OF COSTS FROM WIRELESS SENSORS Results from SensoByg: Placing of sensors by non-experts No delay of concrete casting Sensor cost 10Dansk betonforening

11 Data collecting using wireless sensors SensoByg: Very effective transfer of results direct Brodag to dialogmøde the end user Monitering, hvad har vi gjort, og hvad fik vi ud

12 MORE PRECISE EVALUATION OF DETERIORATION DEVELOPMENT Destructive test Deterioration level Results from sensors Initiation Deterioration phase Propagation 12Dansk betonforening

13 MEASURING METHODS SensoByg: dry SensoByg: wet To use the full potential from sensors: Much more refined measuring methods are needed. 13Dansk betonforening

14 THE FULL POTENTIAL: DURABILITY DESIGN Current practice: Passive durability through use of high quality materials and constructive principles. High use of valuable resources High construction costs Fixed service life Possible future (sustainable) practice: Passive durability within the known service life Monitoring system Plan for active degradation protection. Tunnel wall Water /soil Reduced use of valuable resources Low construction costs Flexible service life 14Dansk betonforening

15 CONDITIONS AT MOST RELEVANT AREAS Area Distance to sensor Temperature interval Stress interval Membrane cm High High/small No Reinforcement Tunnels 1 m Very small Small Yes (no) Other m High High/small Yes / no Tunnels Membrane Other 15Dansk betonforening

16 BONUS: CONSTRUCTION PHASE V/C=0,5 V/C=0,4 Epoxypriming Bituminous membrane Asphalt Monitering, hvad har vi gjort, og hvad fik vi ud 16

17 CONCLUSIONS Large potential for using sensors at infrastructure constructions: Reduced use of resources Reduced construction costs Reduced inspection and maintenance costs To make use of the opportunities sensors must have: Wireless construction Robust construction Documented durability (minimum years) Suitable measuring methods Low production and installation costs 17Dansk betonforening

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