SummaryNavigation locks are critical infrastructure components, and their closure for maintenance and repair can have significant impacts on the global economy. The current state of inspection and monitoring of lock components is generally to close the lock and perform a visual inspection. Whereas structural health monitoring of navigation locks is gaining acceptance, automation of the structural health monitoring process is lacking. This paper reports on efforts to develop an automated damage detection system for miter gates of navigation locks. The study focuses on using strain gage measurements to identify the redistribution of load throughout lock gates in the presence of damage. To eliminate the environmental variability in the data, a new damage-sensitive feature is introduced, termed here as "slope" and defined as the derivative of the strain with respect to the water levels in the lock chamber. The slopes form a new, stationary time series effectively purged of environmental effects. A principal component analysis, a method of analyzing multivariate, stationary time series, is then used to detect significant changes in the statistics of slopes as an indication of damage. To validate the approach, damage is simulated in a finite element model, and the resulting changes in strain from the finite element model are superimposed on the measured data. The results demonstrate the potential of the proposed approach for detecting damage in navigational lock gates.

The U.S. Army Corps of Engineers (USACE) operates and maintains 236 lock chambers at 191 lock sites on 41 waterways throughout the contiguous United States. Waterway navigational locks are important parts of the nation's infrastructure. Locks enable the flow of billions of dollars of commerce and support efforts for flood control. Proper maintenance of the locks and early detection of damage is crucial; however, due to shrinking budgets, adequate funding to apply traditional scheduled maintenance and visual inspection is not available. Structural health monitoring (SHM) systems have been considered to assist in establishing more efficient maintenance, repair, and replacement priorities for navigational locks. This work was undertaken to develop and implement a real-time methodology that provides lock operators with a robust, accurate warning system of gap(s) at the gate-to-wall interface. This initial effort, which focused on horizontally framed miter gates and on damage that is assumed to take the form of a gap at the gate/wall interface (quoin), developed a methodology to identify the occurrence of damage in miter gate structures using data from strain and water level gages that is collected continuously from the SHM system deployed by USACE. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

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