Is Structural Health Monitoring a Hot Research Field in Civil Engineering Today?

Yes, structural health monitoring (SHM) is indeed a hot research field in civil engineering as of 2023. The increasing complexity of infrastructure systems and the need for maintenance safety and longevity have driven significant advancements in SHM technologies.

Key Factors Contributing to Its Relevance

Aging Infrastructure: Many countries face challenges related to aging infrastructure, requiring effective monitoring solutions to assess structural integrity and safety. Technological Advances: Innovations in sensor technology, data analytics, and machine learning have enhanced the capabilities of SHM systems, allowing for real-time monitoring and predictive maintenance. Sustainability: SHM contributes to sustainable engineering practices by extending the lifespan of structures and optimizing maintenance schedules, which can reduce costs and resource consumption. Disaster Resilience: With increasing concerns about natural disasters like earthquakes and hurricanes, SHM plays a crucial role in assessing and improving the resilience of structures. Regulatory Requirements: There is a growing emphasis on compliance with safety regulations and standards, which often necessitates the implementation of SHM systems. Interdisciplinary Research: SHM intersects with various fields, including materials science, data science, and robotics, fostering a rich environment for interdisciplinary research.

Overall, SHM remains a vibrant area of study with implications for safety, efficiency, and sustainability in civil engineering. Its importance is highlighted by its increasing mainstream adoption, as evidenced by the successful deployment of SHM systems in various infrastructure projects.

Mainstream Adoption of SHM Systems

It is certainly becoming more mainstream to rely on the data from SHM systems. My company recently installed a fiber-optic strain gauge system on a large steel deck truss bridge in our state, using it as a relatively low-cost way to determine repair priorities.

Case Study: Evaluating Rocker Bearings with Fiber Optic Strain Gages

During the recent inspection of the rocker bearings supporting the steel deck truss, the bearings appeared to have very little if any movement when compared to prior measurements taken at different temperature extremes. When working properly, there can be a significant amount of movement in these bearings, especially on long spans. Below is a picture of a rocker bearing supporting one side of a span.

Thus, it was suspected that the expansion bearings were either seized due to corrosion, also referred to as freezing. To determine if the bearings were actually frozen, we installed 65 fiber-optic strain gages and linked them to a small PC in an environmentally protected container at the bridge, which would provide remote access via a cell phone modem. Although strain gages have automatic temperature compensation capability, two strain gages called dummy gages were installed on unrestrained plates. One plate was exposed to the sun, and the other was kept in the shade. Below is an example of a strain gauge.

Below is a graph of our results showing that as the temperature changed, stress in the members increased. In this case, real-world stresses were very close to our calculated estimate. If the bearings were working as designed, i.e., expanding and contracting with temperature changes, we would not have seen much of an increase in stress when temperatures fluctuated.

Our analysis revealed that we did indeed have some frozen bearings, and the spans being supported by those bearings were being overstressed. With these structural monitoring results, the state could more clearly see the urgency of the situation and promptly replaced the bearings.

Conclusion

The success of our SHM project underscores the importance of integrating these technologies into infrastructure management. By leveraging SHM, civil engineers can ensure the safety and longevity of structures, ultimately leading to more resilient and sustainable infrastructure solutions.