14 January 2013

Ben Ford, a Costain undergraduate engineer at the University of Exeter, has won a regional structural engineering award for his research into using optical fibre sensing to monitor strain within sprayed concrete.

Ben won the Student Competition which was organised by the Devon and Cornwall Regional Group of the Institution of Structural Engineers, the world’s largest membership organisation dedicated to the art and science of structural engineering.

Supervised by Dr. Khurram Wadee at the University of Exeter, Ben researched and tested how optical fibre cables could be used to measure performance within structures, before identifying where improvements in their specification, design and installation could be made.

Ben started off by identifying what optical fibre strain monitoring was, how it worked, and what its capabilities were. This was achieved through a review of research papers and discussions with Dr Mohammed Elshafie, who leads the Optical Fibre Sensing Group in the Civils Division at Cambridge University’s Engineering Department.

“The monitoring of most structures is currently reliant on maintenance teams performing time consuming and costly visual and manual operations, but the use of optical fibre monitoring systems makes it possible to realise continuous, real time and automatic health monitoring of structures,” said Ben.

Through combining standard optical fibre cables with a BOTDR (Brillouin Optical Time Domain Reflectometry) analyser, Ben measured continuous strain profiles within sprayed concrete beams and explored the potential use of this technology within SMART infrastructure and BIM (Building Information Modelling) Level 3.

“The technology has the potential to revolutionise the way sprayed concrete tunnels are monitored, but all previous applications of the technology in concrete are based around the optical fibre cables being directly attached to reinforcement within the concrete,” said Ben.

Ben, in conjunction with Bonnie Leung, a fourth year undergraduate student at the University of Cambridge, conducted an experiment at the University of Cambridge to see how well the cables performed when cast directly into sprayed concrete, without being attached to any reinforcement.

As part of the experiment, a sprayed concrete column and a sprayed concrete beam were tested, each cast with optical fibre cables and vibrating wire strain gauges for comparison. The column and the beam were loaded individually in small increments and the strain recorded at each load step by optical fibre cables, vibrating wire strain gauges, Linear Voltage Displacement Transducers (LVDT) and traditional Demec gauges.

Comparisons were made between each of the recorded strains, and analysis carried out to determine the cause of any discrepancies.

Both sets of optical fibre results accurately measured the strains during the different loading increments as well as identified crack locations, well before they were visually located, within the beam and the column.

Ben is being sponsored through university as part of a QUEST Scholarship and is currently in his fourth year of a MEng Civil Engineering course at Exeter. He graduates in June and hopes to start work at Costain in August.

“I’m delighted to have won this competition and I want to thank everyone who helped me in my research. A key outcome of my work was to promote the capabilities of optical fibre monitoring to the engineering community, and presenting and winning this competition will help to do that,” said Ben.

Commenting on Ben’s award, Sarah Buck, Chair of the judging panel and a former President of the Institution of Structural Engineers said: "Ben’s presentation on the use of fibre optic cables in sprayed concrete particularly impressed the judges. Ben presented his subject confidently and clearly, whilst his response to questions from the judging panel demonstrated his in-depth knowledge of the subject at both a technical and practical level. He is a worthy winner of the first prize of the Devon and Cornwall Regional Group Student Presentation Competition and he is credit to Exeter University and Costain."

Tim Embley, Costain’s Group Innovation and Knowledge Manager, added: “Innovation is part of Costain’s culture and I congratulate Ben on his award. Our research and innovation programme, along with our research partners like Cambridge University, aims to develop innovative solutions to improve our customers’ businesses.”

 

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