Full-Scale Testing of Miter Gate Components with Multiple Adjacent Fillet and Butt Welds to Estimate Fatigue Performance

Abstract

Miter gates are common structures at navigation locks and allow vessels to traverse the lock. Each time the lock passes vessels, miter gates experience loading cycles and thus accumulate fatigue damage. In the United States, fatigue analysis for miter gate welds is typically performed using code-based approaches with predefined weld details, which are oftentimes only marginally similar to the detail being analyzed. To overcome this issue, fatigue testing is performed in this study on full-scale specimens that represent the most common component found on miter gates. The component’s weld detailing consists of multiple intersecting plates with a combination of fillet and butt welds in close proximity that typically undergoes a combination of axial and bending loads. The proximity of multiple welds of different types along with the complicated state of loading introduces a great deal of uncertainty regarding estimation of fatigue life using code-based approaches, where specific details need to be selected from tabulated options. To overcome this issue, 12 specimens were fabricated for this study and tested to failure, and a stress–life cycle (S-N) curve is calculated to aid designers in estimating the fatigue life of these welded joints. The slope of the S-N curve found in this study is 6.8% lower than slope used in code-based approaches, while the intercept of the S-N curve found in this study is 5.8% higher. This leads to the fatigue life of the specimens tested herein exceeding that predicted by code-based approaches typically used in the United States by a factor of 2. The statistics of the data and the confidence intervals for the developed S-N curve are also provided to enable more rigorous incorporation of uncertainty in future fatigue analysis. The results of this study will enable more accurate life-cycle analysis for this infrastructure and allow for more effective maintenance planning with potential cost savings via more effective inspection intervals.