Abstract
Monitoring of fatigue cracking in steel bridges is of high interest to many bridge owners and agencies. Due to the variety of deterioration sources and locations of bridge defects, there is currently no single method that can detect and address the potential sources globally. In this paper, we presented a dual mode sensing methodology integrating acoustic emission and ultrasonic wave inspection based on the use of low-profile piezoelectric wafer active sensors (PWAS). After introducing the research background and piezoelectric sensing principles, PWAS crack detection in passive acoustic emission mode is first presented. Their acoustic emission detection capability has been validated through both static and compact tension fatigue tests. With the use of coaxial cable wiring, PWAS AE signal quality has been improved. The active ultrasonic inspection is conducted by the damage index and wave imaging approach. The results in the paper show that such an integration of passive acoustic emission detection with active ultrasonic sensing is a technological leap forward from the current practice of periodic and subjective visual inspection and bridge management based primarily on history of past performance.
Highlights
According to the Federal Highway Administration (FHWA) National Bridge Inventory (NBI) of 2007, the number of structurally deficient and functionally obsolete bridges is 72,524 and 79,792, respectively [1]
As the inventory continues to age, routine inspection practices will not be sufficient for the timely identification of areas of concern and to provide enough information to bridge owners to make informed decisions for safety and maintenance prioritization
The work presented here intends to explore Piezoelectric wafer active sensors (PWAS) applications for in-field monitoring of infrastructure using both acoustic emission and active wave propagation sensing. Laboratory demonstration on both thin aluminum and thick steel plates, the PWAS have been proved as AE sensors
Summary
According to the Federal Highway Administration (FHWA) National Bridge Inventory (NBI) of 2007, the number of structurally deficient and functionally obsolete bridges is 72,524 and 79,792, respectively [1]. Piezoelectric wafer active sensors (PWAS) can function as an active sensing or passive device or network using piezoelectric principles and provide a correlation between mechanical and electrical variables They can be permanently attached to the structure to monitor condition at will and can operate in active guided wave interrogation or passive AE sensing modes. The dual mode sensing allows PWAS to operate in passive AE mode throughout the entire monitoring process unless significant AE events are detected, indicating major crack presence in the structure. When an AE event is identified, the PWAS can be switched to active mode to interrogate the bridge structure with propagating guided waves to assess the crack size and location. An entire steel bridge may be mapped with the guided wave interrogation with visualized crack damage
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