Viability of embedded ultrasonic sensors for structural health monitoring of concrete cracking
Open Access
- Author:
- Reiter, Joseph Brian
- Graduate Program:
- Civil Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- May 23, 2012
- Committee Members:
- Shelley Marie Stoffels, Thesis Advisor/Co-Advisor
Dr Joseph Rose, Thesis Advisor/Co-Advisor - Keywords:
- Concrete
Ultrasonic
Structural Health Monitoring
Health Monitoring
Embedded Sensors
Piezoelectric - Abstract:
- Concrete infrastructure is an integral part of a transportation system. Concrete is used in many bridges and a large percent of the U.S. highway system. Determining the condition of the concrete bridges and pavements is essential for proper maintenance of these structures. The current system for determining maintenance in the US is based on maintenance time schedules or on condition surveys performed at varying intervals. Recent developments with sensors and sensing systems could allow more frequent and even real-time monitoring of the concrete structures to determine structural health. Through the use of Structural Health Monitoring (SHM) concepts and ultrasonic embedded sensors, a system was constructed that is capable of detecting cracking in a standard ASTM C78 concrete beam specimen. The system consisted of a pulser/receiver and ultrasonic sensors. Two types of piezoelectric ultrasonic sensors were constructed and embedded in concrete beam specimens which were subjected to cracking. The first sensor was constructed using radially activated disc piezoelectric elements and the second sensor was constructed from bender, or bimorph, piezoelectric elements. Following construction of the specimens determining the detection capability of the system required the creation of cracking in the beam specimens. Idealized laboratory cracking was created by saw-cutting the beam specimens in a regular pattern and analyzing the resulting ultrasonic signals. The same procedure was then used with controlled loading to detect real cracks in a beam specimen. The resulting signal data from testing was analyzed by using a power ratio calculation which related a baseline signal power calculation to power calculated at varying times during curing, and different stages of testing. The power ratio calculation combined with the SHM test procedure and the embedded ultrasonic sensors was able to detect the sawcut crack, and the real crack created in the concrete beam specimens.