Principal Investigator: Caroline Bennett
About this Project
Brief Project Description & Background
This project is aimed at developing practical and effective retrofits for skewed steel bridges that are damaged by distortion-induced fatigue. Aging, skewed steel bridges are highly susceptible to distortion-induced fatigue due to their geometry. Additionally, when cross-frames are framed such that they are parallel to the skew angle, retrofitting becomes increasingly difficult due to the acute angle at the connection. Therefore, retrofit techniques are needed that can effectively repair cracking in these locations, and that can be performed with minimal disruption to the traveling public.
The research objective of this project is to develop effective, economical, and practical retrofit techniques for skewed steel bridges susceptible to distortion-induced fatigue.
The benefit of this research is obtaining a retrofit technique that will halt crack propagation in skewed steel bridges. Additionally, the retrofit developed will be aimed at repairing bridges in a manner that minimizes disruption to the traveling public and can quickly be implemented by state DOTs.
Distortion-induced fatigue is the most common cause for fatigue cracking in steel bridges. Skewed steel bridges are highly susceptible to this failure mode. Skewed bridges in which the cross-frames are placed parallel to the angle of skew are very difficult to repair due to the acute angle between the bent-plate and the girder line. Retrofit techniques are urgently needed to repair fatigue cracks in this type of connection details.
A research program is proposed in which girder sub-assemblies with skewed cross-frames will be tested under distortion-induced fatigue loading. The goal of the study is to develop repair methods that will also be tested in the physical specimens. It is anticipated that multiple test trials can be conducted with each specimen, allowing for the evaluation of several repair techniques. A suite of finite element analyses will be performed to complement the physical tests and to aid in the development of the retrofit measures. The proposed research directly addresses the following U.S. Strategic Goals: (1) Enhancing safety, (2) Improving the state of good repair, and (3) Improving the environmental sustainability of the U.S. surface transportation system.
Recommendations will be provided regarding the implementation of the various retrofit measures that are developed.