Acoustic emission from tendon wire breaks in post tensioned concrete girders

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Vector Inc supplies products and services related to concrete restoration and corrosion. They are investigating**methods for monitoring of corrosion of tendons that are used to reinforce concrete structures. Concrete is one**of the mostly widely used construction materials in civil structures. In most instances, it requires some form of**reinforcing in order to meet the tensile strength requirements for a particular application. In post-tensioned**concrete structures, the tensile strength of composite system relies on all the steel tensioned cables operating**close to their ultimate breaking strength. Steel even encased in concrete will corrode over time, and if the**corrosion is sufficient, the stress with the cables will exceed the breaking strength and the wires that make up**the cable will begin to break. The proposed research will aid Vector in determining the suitability of using**acoustic emission for the detection of wire breaks in steel tensioning cables (tendons).**Post-tension cables have considerable strain energy stored in them, and if a wire in the cable breaks, this energy**is released in various forms including acoustic energy. This acoustic energy is released in a short pulse that will**couple into and travels throughout the structure. Microphones attached to the structure can be used to pick up**the arrival of these acoustic pulses. With a few microphones, the difference in arrival time between pulses can**be used to determine the approximate position of a wire break. However, the propagation of acoustic pulses**through post-tensioned concrete structures is poorly understood.**This work will enable Vector to design acoustic emission-based post-tension wire break monitoring systems.**The proposed research will provide the knowledge about the amplitude of the acoustic pulses, the frequency**content of the acoustic pulses, the attenuation of the acoustic pulses, and the dispersion of the acoustic pulses in**prestressed concrete composite systems that is needed. The knowledge generated though this project will**enable Vector to develop a new product line of monitoring systems to address the world-wide problem of**detecting wire breaks in large post-tensioned structures.**