Date of Graduation

8-2018

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Prinz, Gary S.

Committee Member

Murray, Cameron D.

Second Committee Member

Hale, W. Micah

Keywords

Fatigue; Pre-stress; Retrofit; Waterway

Abstract

Steel waterway lock gates across the national inland waterway transportation network are reaching and exceeding their intended service life, often experiencing component failures that lead to service interruptions. Unscheduled maintenance and repair of lock gates can be expensive and cause economic ripples throughout the entire inland waterway network. These lock gate component failures are often caused by fatigue cracking from repeated loading during operation. This thesis develops and tests a prestressed carbon fiber reinforced polymer (CFRP) fatigue retrofit for controlling fatigue demands within lock gate components. The study expands upon a recent analytical work by Lozano (2017) by experimentally investigating prestressing strategies, bonding mechanisms, prestress creep/relaxation performance, and large-scale experimental fatigue testing. A total of seven large-scale cyclic tests were conducted on lock gate components (with and without applied retrofits) to gauge the effectiveness of the developed prestressing strategies. All gate specimens tested were artificially notched to create a local stress concentration and worsened fatigue condition. Results indicate that the addition of the prestressed CFRP retrofit increases the fatigue life of the retrofitted gate component despite the prestress loss due to epoxy adhesive debonding following rapid cyclic loading. The retrofitted specimen experienced a fatigue life increase of nearly 3 times over the un-retrofitted specimen. Additionally, load shedding into the CFRP, even without significant prestress applied, contributes to a reduction in the component notch stress. The applied CFRP clamping force is able to provide enough force transfer to the CFRP to reduce the notch local stresses.

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