Acoustic emission from tendon wire breaks in post tensioned concrete girders

Vector Inc提供与混凝土修复和腐蚀相关的产品和服务。他们正在研究监测用于加固混凝土结构的钢筋束腐蚀的方法。混凝土是土木建筑中使用最广泛的建筑材料之一。在大多数情况下，它需要某种形式的加强，以满足特定应用的拉伸强度要求。在后张预应力混凝土结构中，组合体系的抗拉强度依赖于所有的钢拉索在其极限断裂强度附近工作。即使是包裹在混凝土中的钢也会随着时间的推移而腐蚀，如果腐蚀足够严重，电缆的应力将超过断裂强度，组成电缆的电线将开始断裂。拟议的研究将有助于Vector确定使用 ** 声发射检测钢拉索（钢筋束）中钢丝断裂的适用性。**后张拉电缆中储存了相当大的应变能，如果电缆中的电线断裂，这种能量 ** 会以各种形式释放，包括声能。这种声能以短脉冲的形式释放，将耦合到整个结构中并在其中传播。安装在结构上的麦克风可以用来接收这些声脉冲的到来。通过几个麦克风，脉冲之间的到达时间差可以用来确定断线的大致位置。然而，声脉冲 ** 通过后张混凝土结构的传播知之甚少。这项工作将使Vector能够设计基于声发射的后张力断线监测系统。**该研究将提供有关声脉冲的振幅、声脉冲的频率 ** 内容、声脉冲的衰减以及声脉冲在 ** 预应力混凝土复合系统中的分散度的知识。通过该项目产生的知识将 ** 使Vector能够开发新的监测系统产品线，以解决 ** 检测大型后张结构中的钢丝断裂的世界性问题。**

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.**