Acoustic emission from tendon wire breaks in post tensioned concrete girders

向量公司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筋的腐蚀的方法。混凝土是民用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**加固，以满足特定应用的抗拉强度要求。在后张法混凝土结构中，复合体系的抗拉强度依赖于所有接近其极限断裂强度的钢拉索。即使包裹在混凝土中的钢材也会随着时间的推移而腐蚀，如果腐蚀程度足够大，电缆的应力将超过断裂强度，组成电缆的钢丝将开始断裂。拟议中的研究将帮助矢量确定**声发射用于检测钢索(筋)断丝的适宜性。**后张拉索中储存了相当大的应变能，如果缆索中的一根钢丝断裂，这种能量**以各种形式释放，包括声能。这种声波能量在一个短脉冲中释放，它将耦合到结构中并在整个结构中传播。安装在该结构上的麦克风可以用来拾取**这些声脉冲的到达。有了几个麦克风，脉冲之间的到达时间差就可以**用来确定断线的大致位置。然而，声波脉冲在后张法混凝土结构中的传播**还知之甚少。**这项工作将使矢量能够设计基于声发射的后张法断丝监测系统。**拟议的研究将提供有关声波脉冲的幅度、声波脉冲的频率**含量、声波脉冲的衰减以及**预应力混凝土组合系统中声波脉冲的色散的知识。通过这个项目产生的知识将**使矢量公司能够开发新的监测系统产品线，以解决**检测大型后张法结构中的钢丝断裂这一世界性问题。**

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.**