Fracture Behavior of Internal Tendon in PSC Structure Using Acoustic Emission Technique

Pre-stressed concrete (PSC) is used for tension members, called tendons that can be located either outside or inside the concrete. These structures are frequently used in the construction of bridges such as highway overpasses. External tendons can be accessed by an inspector, and can be assessed using various inspection methods in case of failure. However, since the internal tendon is located inside the concrete, detection of defects using existing non-destructive testing technology is limited. In the present work, acoustic emission (AE) techniques were used to monitor the fracture behavior of internal tendons in PSC bridges. The abnormalities in the tendons were detected through the analysis of specific measurement data obtained during the failure of the internal tendon. The physical behavior of the PSC structure was observed by applying cyclic loads and tensile failure testing to artificially damaged tendons inside specimens of grouted PSC. During cyclic load testing, values of AE energy 1000 aJ over the reference signal level were measured twice when the maximum load of 6.5 tons was reached. AE energy values were measured over 10,000 aJ, and when the load reached 13 tons, approximately 50,000 aJ of AE energy was measured suddenly as the tendon failed. From measurements taken during repeated load tests and tensile failure testing, the concrete failure behavior was classified using the measured AE energy, Ib-value, and frequency features. These results confirm that the failure behavior of PSC tendons can be analyzed in terms of the initiation and reverberation frequencies