Loads for Fatigue Life Assessment of Gates at Navigation Locks

Abstract

The U.S. inland navigation infrastructure is deteriorating primarily due to the aging of its components and the operation at near to full capacity of the system's structures. Gates at navigation locks play an integral part in keeping navigation traffic continuously moving, and their reliability is essential to the navigation infrastructure. Assessments of fatigue reliability as a function of time for existing gates at navigation locks require knowledge of loading cycles. This assessment can contribute to the economic evaluation of the remaining fatigue life of critical fatigue details in gates. The accuracy of this assessment depends in part on the accuracy of the loading cycles used in the reliability analysis. Water elevations from hydraulic records were used to compute water-head differentials on the miter gates. Loading or hardware cycles were obtained from the U.S. Army Corps of Engineers (USACE) lock performance monitoring system (LPMS), and were then combined with head differential to obtain loading histograms for the gates. These histograms are needed to successfully perform fatigue reliability analyses. A probabilistic model was also developed for predicting the number of loading or hardware cycles for the gates. This paper includes an example to demonstrate the suggested methods and models for fatigue reliability assessment.