Analytical and experimental investigation for distortion-induced fatigue in steel bridges

Distortion-induced fatigue has been extensively studied; however, retrofit techniques currently used are expensive and/or time consuming to implement. These retrofit techniques primarily fall into two categories--stiffening or softening the weak web-gap region. The University of Kansas has developed an innovative stiffening technique that is economical to implement. This technique requires two angles providing attachment between the connection plate and girder web with a plate placed on the other side of the web to distribute out-of-plane forces (called angles-with-plate retrofit). Another appealing aspect of the angles-with-plate retrofit is the minimal traffic disruption required during retrofit application. Through analytical and experimental testing, the angles-with-plate retrofit has been shown to be effective in halting or slowing distortion-induced fatigue crack growth.;This dissertation is divided into five parts and appendices. The first two parts are an analytical investigation of parameters influencing distortion-induced fatigue and current retrofit techniques on a full-scale bridge in Abaqus. Parts 3-5 are analytical and experimental investigations of the angles-with-plate retrofit on a 9.1 m [30 ft.] test bridge. Each part within the document contains particular formatting associated with published or expected publishing requirements.;Part 1: Effects of Lateral Bracing Placement and Skew on Distortion-Induced Fatigue.;Part 2: Distortion-Induced Fatigue in Steel Bridges: Causes, Parameters, and Fixes.;Part 3: Experimental Investigation of Distortion-Induced Fatigue Repair in a 9.1 m [30 ft.] Bridge System.;Part 4: Parametric Retrofit Analysis for Distortion-Induced Fatigue in a 9.1 m [30 ft.] Bridge System.;Part 5: Innovative Retrofit Technique for Distortion-Induced Fatigue Cracks in Steel Girder Web Gaps.