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Health Monitoring of Prestressing Tendons in Post-tensioned Concrete Structures
Conference proceeding

Health Monitoring of Prestressing Tendons in Post-tensioned Concrete Structures

Salvatore Salamone, Ivan Bartoli, Claudio Nucera, Robert Phillips and Francesco Lanza di Scalea
SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2011, v 7981(1), pp 798122-7981210
01 Jan 2011

Abstract

Engineering Engineering, Electrical & Electronic Engineering, Multidisciplinary Optics Physical Sciences Science & Technology Technology
Currently 90% of bridges built in California are post-tensioned box-girder. In such structures the steel tendons are the main load-carrying components. The loss of prestress, as well as the presence of defects or the tendon breakage, can be catastrophic for the entire structure. Unfortunately, today there is no well-established method for the monitoring of prestressing (PS) tendons that can provide simultaneous information related to the presence of defects and the level of prestress in a continuous, real time manner. If such a monitoring system were available, considerable savings would be achieved in bridge maintenance since repairs would be implemented in a timely manner without traffic disruptions. This paper presents a health monitoring system for PS tendons in post-tensioned structures of interest to Caltrans. Such a system uses ultrasonic guided waves and embedded sensors to provide simultaneously and in real time, (a) measurements of the level of applied prestress, and (b) defect detection at early grow stages. The proposed PS measurement technique exploits the sensitivity of ultrasonic waves to the inter-wire contact developing in a multi-wire strand as a function of prestress level. In particular the nonlinear ultrasonic behavior of the tendon under changing levels of prestress is monitored by tracking higher-order harmonics at (n omega) arising under a fundamental guided-wave excitation at (omega). Moreover this paper also present real-time damage detection and location in post-tensioned bridge joints using Acoustic Emission techniques. Experimental tests on large-scale single-tendon PT joint specimens, subjected to multiple load cycles, will be presented to validate the monitoring of PS loads (through nonlinear ultrasonic probing) and the monitoring of damage progression and location (through acoustic emission techniques). Issues and potential for the use of such techniques to monitor post-tensioned bridges in the field will be discussed.

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Collaboration types
Domestic collaboration
Web of Science research areas
Engineering, Electrical & Electronic
Engineering, Multidisciplinary
Optics
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