See attached file for background.

Distortion-induced fatigue cracks constitute a serious national problem given the large number of steel girder bridges constructed before 1985 that are affected by this type of failure. It is estimated that 90% of all fatigue-related cracks in bridges have arisen due to out-of-plane distortion (Connor and Fisher 2006). Finding, repairing, and potentially preventing fatigue cracks at details susceptible to out-of-plane distortion represents a significant expense to State DOTs. This problem is exacerbated by the fact that many of the affected bridge structures carry large traffic loads, or their geographical location is such that temporary closure would cause significant disruption to the economic activity of the local residents. While a number of repair and retrofit methods have been shown to be effective in addressing this problem (Roddis and Zhao 2001; Roddis and Zhao 2003; Stallings et al. 1999; Connor and Fisher 2006), these strategies can be time-consuming, expensive to implement, and often require temporary bridge closures. There are also instances in which these methods cannot be implemented due to lack of space in the affected region of the bridge. In those cases, the use of new and/or combined techniques may present a viable method for fatigue life extension. The main objective of the proposed research is to explore the use of composite materials and hole treatments (ultrasonic impact treatment and bolt interference) to develop new retrofitting techniques aimed at extending the fatigue life of bridges with connection details susceptible to distortion-induced fatigue. The techniques that will be studied were selected because they are relatively inexpensive, easy to implement, and can be carried out without significant disruptions to traffic.

The proposed study will investigate innovative techniques for improving the fatigue life of steel girder bridges, specifically focusing on the urgent and ubiquitous problem of distortion-induced effects. The project will include computational and physical simulations of girder assemblies to evaluate the effectiveness of various retrofit techniques. See attached file for more details on scope of work.

The committment requested from each partner is $75,000 which may be transferred over a three year period. The research will be conducted at the University of Kansas by Stan Rolfe, Adolfo Matamoros, Caroline Bennett and Ron Barrett-Gonzalez.