Date of Award

Winter 2019

Project Type


Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

Erin S Bell

Second Advisor

Eshan V Dave

Third Advisor

Robert M Henry


Steel truss bridge gusset plates have been difficult to inspect and can potentially hide damage, which could accumulate and lead to collapse. Recently, bridge design methods have evolved to address the problems of traditional gusset plates. These new designs eliminate the plated connections altogether and instead rely on built-up steel connections that provide a smooth transition zone between the cords and diagonal members. Consequently, the gusset-less connections rely heavily on the performance of the welds that hold their elements together.

Given the increased role of welding on these new gusset-less truss connections, the question of the impact of the welding quality on the overall structural performance of these members had to be addressed. To investigate the effect of weld quality on the new connections, a laboratory experiment was conducted. This experiment consisted of comparing the fatigue performance of perfectly intact and defective weld samples. The samples were cyclically loaded and unloaded until they fractured. It was then determined if there was a relationship between how many cycles each sample endured before failing and the level of defect present on each sample. Ultimately, an exponentially decaying relationship was observed to exist between the quality of welds and the fatigue performance of the samples.