Field, Laboratory, and Analytical Investigation of Angles-with-Plate Retrofit for Distortion-Induced Fatigue in Steel Bridges

Abstract

Prior to the mid-1980s, steel girder bridges were designed with a detail susceptible to distortion-induced fatigue cracking. While a number of retrofit measures have been developed to repair this problem, many of those retrofits have long-term performance issues or are difficult and expensive to implement. Recent research at the University of Kansas has focused on the development of a new retrofit measure that could be effective in repairing distortion-induced fatigue cracking while also being inexpensive and easier to install than currently available retrofits. This new retrofit measure, referred to as the “angles-with-plate” retrofit, stiffens the problematic region and redistributes distortion-induced fatigue stresses away from cracking prone areas. By eliminating the need for cumbersome installation procedures, the angles-with-plate retrofit also provides a more economical repair that can be implemented with minimal traffic interruptions. This dissertation is presented in three parts and appendices. Part I provides a brief overview of distortion-induced fatigue cracking and the development of the angles-with-plate retrofit. Part II gives details and findings of an experimental investigation of the performance of the angles-with-plate retrofit and a stiffened version of the angles-with-plate retrofit on a 9.1 m (30 ft.) laboratory test bridge. Part III describes field and analytical tests performed on an active steel girder bridge system near Park City, Kansas on which the angles-with-plate retrofit was used as a repair for distortion-induced fatigue cracking.