Where Are They Now? - ESAI Postgraduate Researcher 2015 Luke Prendergast

Welcome to the second part of the ESAI Postgraduate of the year Where Are They Now series where we will be revisiting our postgraduate of the year winners throughout the years. Next up is Dr Luke J. Prendergast who was our winner in 2015 for his research titled “Monitoring of scour around structures using changes in natural frequency of vibration”. Many thanks to Luke for his sharing with us his thoughts and experiences and we wish him the very best of luck in the future.

1.    So Luke, to start off, could you please give us a brief introduction to your PhD research?

I did my PhD in the School of Civil Engineering at University College Dublin and graduated in 2015. My research topic focussed on identifying if it is possible to use vibrations from structures to detect erosion of soil from around their foundations. The types of structures this applies to include bridges and offshore wind turbines, as both can be affected by this erosion, called scour. Scour erosion is mainly detected by divers who inspect the foundations of these structures over time, or by using sensors installed into the soil that can detect when the soil is eroded away. The main issue with these approaches is that they cannot tell you how the structure itself ‘feels’ the scour, which is one of the main reasons for sudden bridge failure worldwide. My research aimed to improve this by analysing how the vibrations of a structure change when scour affects the foundations, and used both experimental testing and numerical modelling. The vibrations of the structure give us an idea how the structure is interacting with the ground and so is an improvement on traditional approaches. The experiments I conducted included a large-scale scour test on a pile, installed in dense sand. This pile was fitted with vibration sensors, called accelerometers, and an excavator was used to remove sand from around the pile corresponding to an increase in the depth of a scour hole that could be caused by flood water. By analysing the pile vibrations at each depth of scour, it was possible to obtain the vibration frequency of the pile, and this showed a significant sensitivity to the increasing scour. From this experiment, I went on to create computer models (numerical simulations) of bridges traversed by vehicles so that I could check if a bridge would have the same sensitivity to scour as a single pile. It turns out that the vibration frequency of bridges can be affected by scour, so the approach showed promise at working on real bridges. I also developed a computer model of an offshore wind turbine to test the same idea and this also showed potential success.  

2.    What role you are currently working in, and how has your postgraduate studies helped shape where you are now?

I am currently an Assistant Professor in Civil Engineering at University of Nottingham in the UK. My role is to lecture in the topics of Structural Analysis and Geotechnical Engineering, both of which were core to my PhD research. My own research today still looks at scour detection using dynamics and vibrations, and has moved into more advanced methods including analysing the vibrations of vehicles traversing scoured bridges and even using drones to move sensors around a bridge on a network. My PhD research is directly applicable to the role I am currently working in.

3.    Where did you find out about the ESAI Postgraduate of the year competition, and how did you feel when you found out you had won?

I believe I received an email about the competition while I was preparing for my Viva Voce (PhD exam). I remember being encouraged to apply by my supervisor. I was in disbelief (and delighted) when I won it to be honest, but this was mostly as I felt I did not fit into the category of an Environmental Scientist. I now know that this is very broad, and clearly the topic was of interest.  

4.    Since finishing your PhD, are you pleased with the developments in flood-induced scour detection, in particular from an Irish context?

Yes, the field has grown considerably, especially around the world. When I was doing my PhD, there were few full-scale applications of using vibration measurements to detect scour erosion. Now, there are several documented examples each showing good results. Most of these to date are in places like Taiwan and Japan, and most have been applied to large cable-stayed bridges. In an Irish context, developments are ongoing. It is important to note that science moves slowly at times, and it has only been 5 years since I finished my own PhD, but in that time there has been an explosion of research papers on the topic of vibration-based scour detection so I believe this will be an area of interest for years to come.     

5.    Do you have any advice for those PG students who may be hesitant about applying this year?

Apply. Do it. I remember sitting down on a Friday evening in August 2015 to start my application. I gave myself a window of something like 4 hours to do it. I was preparing for my PhD viva at the same time so I had my thesis in front of me. I recall that the application involved describing my research, explaining its importance to society and the main findings, and describing how it improves on the state of the art. So, if anything, the application was good preparation for my PhD viva. I did not expect to win it, but the application itself was certainly worth doing.  

6.    And finally as you are aware, the postgraduate of the year award comes with €500 prize money. If you won the PG of the year award in 2020, what would you spend it on?

Good question. It’s a good chunk of money so I might be inclined to buy something like a computer or some accessories like that, to help towards research. I might also be inclined to go on holidays! When you win a prize like this that you didn’t expect, it’s always better to use the money on something you have been putting off. Treat yourself!  

Further information on Luke’s research may be found here.

This years Postgraduate of the year competition is open until Sept 30th 2020, so be sure to get your applications in and be in with a chance of the winning €500, an invitation to present at Environ 2021, and title of ESAI Postgraduate Researcher of the year 2020! Further information can be found on the ESAI website.


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