Predicting the Ultimate Load Capacity of Concrete Bridge Beams from the "Relaxation Ratio" Analysis of AE Signals

Michael Forde, Sabrina Colombo, Ian Main, Masayasu Ohtsu, Mitsuhiro Shigeishi

Research output: Contribution to journalMeeting abstractpeer-review


This paper builds on earlier work at the Universities of Edinburgh and Kumamoto and suggests a new paradigm for assessing the load carrying capacity of existing structures. Earlier work presented an alternative approach to the problem, based on "full-scale site testing" the real structure rather than trying to model it using a finite element program with inevitable divergence from reality due to a combination of over-simplification and lack of material property details. Experiments on Reinforced Concrete (RC) beams, representative of bridge beams, are described. The beams were loaded in cycles up to failure whilst recording the acoustic emissions (AE) generated. The analysis of the AE signals was then undertaken based on a proposed new parameter, named the "relaxation ratio". This quantifies the AE energy recorded during the unloading and loading phases of a cycle test and it showed a clear correlation with the bending failure load of the RC beams. A change in trend was noted when the load reached approximately the 45% of the ultimate bending load. The results appeared to be influenced by factors such as the concrete strength and loading rate and further work is needed to extend the results to full scale testing of bridge beams.
Original languageEnglish
Pages (from-to)359
Number of pages364
JournalJournal of Acoustic Emission
Publication statusPublished - 5 Dec 2016


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