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Training in Reducing Uncertainty in Structural Safety

Periodic Reporting for period 2 - TRUSS (Training in Reducing Uncertainty in Structural Safety)

Reporting period: 2017-01-01 to 2018-12-31

TRUSS is a Marie-Sklodowska Innovative Training Network sponsored by the European Commission, that aims to protect Europe’s infrastructure. European infrastructure is ageing. Decades of use, population growth, and changing environmental conditions are taking their toll. Managing this deterioration is tricky because it’s not always clear how to best identify and repair structural flaws early – before they cause safety issues or require a major financial investment to fix. This innovative new training program aims to help solve this issue.

The broad goal of the program is to ensure that Europe’s buildings, roads, railways, ships, and energy plants continue to serve the population safely for decades to come. The program fosters a unique pairing of academic training and industrial application, with a bit of public outreach thrown in. The participants include fourteen early-stage researchers, also called ESRs, who are recruited from all over the world. Each participant is expected to complete structured training, perform novel research, and publicly disseminate their work. For their efforts, the ESRs will receive doctoral degrees following a successful VIVA defence of their research – not to mention an excellent head start on a productive career in infrastructure preservation.

The highly collaborative, multidisciplinary training network consisted of six universities, eleven industry participants, and one research institute from five European countries. Each ESR was assigned a main supervisor from one institution and sector (academic or industrial) and a co-supervisor from another. Aside from hands-on experience at the main hosting institution, training consisted of secondments at other institutions within the TRUSS network. The ESRs also participated in network-wide meetings every 6 months that included intensive, highly-focused modules on different topics related to the assessment of structural safety as well as on business and entrepreneurial skills. At these meetings, the ESRs also gave seminars on the state of their research projects. This setup gave ESRs exposure to different sectors, access to a wide range of subject-matter experts, and a chance to work on communication skills.
The focus of the research projects was varied. One topic of interest was understanding the structural soundness of concrete. For example, ESR1 looked at the reliability of concrete structures made with braided Fibre-Reinforced Polymer (FRP) rebar to avoid corrosion, and ESR2 developed a Post-installed Screw Pull-out (PSP) test, that overcomes limitations of existing Non-Destructive Tests (NDTs).

Energy infrastructure was another focal point. ESR3 identified processes to reduce uncertainty in the design of free-standing nuclear-spent fuel racks, while ESR4 studied practices for optimizing the design of offshore wind turbine towers, both aiming to reduce design time considerably, and identifying relevant sources of over-design.

In the realm of Europe’s nautical interests, ESR5 examined a framework for managing fatigue cracks in ship structures based on time-variant reliability analysis, life cycle risk assessment, value of information theory and Bayesian decision analysis, and ESR6 investigated ways of assessing the residual life of ship unloaders using site-specific data and dynamic modelling of the trolley and payload.

Over half the ESRs focused on rail and road infrastructure. Many sought to improve how we monitor bridge health. ESR7 looked at ways of assessing bridge condition using rotation measurements due to vehicle loads while ESR10 used raw vibration data without the need to derive modal information. ESR9 investigated condition monitoring and fault diagnosis methods to pinpoint how and where railway infrastructure is likely to break down, and ESR8 compared different damage indicators that can be incorporated into bridge safety models.

A few ESRs worked on developing/exploiting new technology to assess structural safety. ESR11 moved forward the application of Distributed Fibre Optic Sensing (DOFS) to monitor concrete structures justifying how and which bonding agents should be used with DOFS, while ESR12 designed an instrumented vehicle, based on the capabilities of the Traffic Speed Deflectometer (TSD), that can detect when a bridge has been damaged from drive-by measurements.

Technology was also a popular method for tracking road conditions. ESR13 used trucks outfitted with sensors to assess how pavement is holding up and affecting fuel consumption at a truck fleet and road network level, and ESR14 looked at ways of automatically monitoring road infrastructure using Unmanned Aerial Vehicles (UAVs).

But it wasn’t all training and research. Those who initiated TRUSS were keenly aware of the importance of disseminating results – both to fellow professionals and to the public at large. All ESRs helped host events geared towards teaching students at all levels the fundamentals of structural failure. Each ESR also shared their work in lay terms through blogs and social media.
As an example of the potential impact of FRP, the current expenditure in repairing steel corrosion in bridges by the US administration is over $20 billion per year. The PSP test will serve as a safe and fast alternative to existing NDT methods for assessing the structural strength of concrete.

Nuclear-spent fuel storage capacity will be optimized, with subsequent reduction of risk in transportation or alternative storing. Design procedures for wind turbines will be improved reducing design time, thus enabling optimization procedures.

A holistic risk-based method for jointly optimizing design and maintenance plans for ships subjected to fatigue will minimize costs. A site-specific investigation and modelling of the load will avoid unnecessary replacements of ship unloaders.

Rotation measurements, damage indicators, condition and diagnostics methods, and vibration parameters other than modal, will have a medium-term impact on bridges in terms of quicker, cheaper and more accurate inspections.

DOFS will have an impact on how professionals proceed when deploying the sensors and analyse measurements, and UAVs will facilitate the foundation for a transition towards rapid, affordable, safe surveying and automated data processing. Drive-by monitoring may not be commercially exploitable for bridge damage detection purposes until the next generation of high accuracy measurement devices is installed, when it will become a powerful means of quickly screening the entire bridge stock. Finally, road authorities can use relationships between fuel consumption and road condition to optimise road maintenance reducing fuel resource use, costs and pollutant emissions.

Overall, TRUSS has shown the power of bringing together high-quality intersectoral and multidisciplinary training in structural safety to the next generation of researchers. The unique design of the initiative allowed individual training programs at university and in industry to leverage their full potential by engaging with each other at an international level. The hope is that the expertise gained through this endeavour will reveal cost-effective, environmentally-friendly ways of preserving Europe’s infrastructure for the next generation.
4-TRUSS Research - Traffic Speed Deflectometer - ESR12 project
6-TRUSS Workshop 1
7-TRUSS Workshop 2
5-TRUSS Training
2-TRUSS Outreach at School
3-TRUSS Research - Accelerometers in Field Test - ESR7 project