Detecting Stress Corrosion Cracking in Bridges
Through laser-based deflection monitoring
Why Stress Corrosion Cracking is so Dangerous for Bridge Structures
Stress Corrosion Cracking (SCC) is a slow but highly dangerous form of damage that can occur particularly in prestressed bridge structures. It arises from the combination of mechanical tensile stress and corrosive agents such as chlorides or moisture – often hidden within the structure of the building.
Particularly affected are the prestressing steels in prestressed concrete bridges, which are susceptible to microscopic crack formation due to the high prestressing and environmental exposure. Over months or years, these cracks grow unnoticed until the sudden breakage of individual tendons or cables occurs. The fatal aspect is that SCC is not visible – neither from the outside nor during a superficial inspection.
When one or more prestressing steels fail due to stress corrosion cracking, the load distribution within the bridge structure changes. Especially in simple-span beams or partially prestressed structures, this results in a measurable increase in deflection – often in the range of just a few millimeters, but clearly detectable by modern sensors.
This change in deflection is a measurable indicator of structural weakening – even without direct access to the prestressing steels.
Solution Approach by Infrasolute: Laser-based Deflection Monitoring in Real Time
Infrasolute offers an innovative, laser-based monitoring system for continuous bridge deflection monitoring. The solution is based on precise laser measurement technology that detects changes in the bridge geometry in real time, providing indications of internal damage such as prestressing steel fractures.
Operating Principle:
- Laser sensors capture the vertical deflection of bridge beams or deck slabs with high resolution.
- When a prestressing steel fracture occurs, the load-bearing capacity changes → increased deflection at critical points.
- The sensors measure continuously – even the smallest changes are detected (in the submillimeter range).
- An integrated gateway transmits the measurement data live to the Infrasolute data portal, where changes are automatically assessed.
Typical Application Areas on Bridge Structures:
- Midfield areas of simple-span or multi-span beams
- Areas with above-average prestressing
- Connection points between prestressed concrete beams and deck slabs
- Structures with known environmental influences (salt, chloride, moisture)
✅ Advantages of Laser-based Deflection Monitoring:
- Early detection of prestressing steel fractures through the geometric response of the structure
- Non-destructive and contactless – no interventions required in the structure
- Autonomous operation through solar power supply and wireless communication
- Submillimeter-precise measurement of vertical deflection
- Real-time alerting in case of threshold exceedance
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Conclusion:
With laser-based deflection monitoring, Infrasolute offers a solution for early warning of structural failure – measurable, low-maintenance, and highly precise. Whether as part of a condition monitoring system or as a targeted measure for known SCC risks, the system provides reliable data for assessing the structural integrity of bridge structures – before damage becomes visible or critical.
Let us advise you!
Benedikt Seuss is your personal contact and advisor in the field of intelligent concrete structures.
