Daniel G. Linzell
Date of this Version
Balakrishna, Chandana C., and Daniel G. Linzell "Examination of Steel Pin and Hanger Assembly Performance – Retrofit to Replacement "
A number of steel, multi-beam bridges exist in the United States that contain pin and hanger assemblies. Pin and hanger assemblies are fracture critical members whose failure would result in collapse of the bridge or render it unable to perform its expected functions. As these bridges continue to age, many assemblies have deteriorated to a point where retrofit or replacement has to be considered and performed to maintain intended safety and performance. States have taken various approaches to address the pin and hanger assembly retrofit and replacement options. However, there is no single document that summarizes these approaches.
This research documents steel pin and hanger assembly retrofit and replacement options via a literature review, extensive survey, and analysis that explore the performance of options that have been studied and implemented in the United States. In association with the literature review, a survey was developed in conjunction with the Bureau of Sociological Research (BOSR) at the University of Nebraska-Lincoln to assist with identifying implemented strategies and evaluate best practices. Information was solicited from 50 states and was used in conjunction with the literature review to develop flowcharts that would assist engineers with assessing various options and their consequences when pin and hanger assembly retrofit or replacement options are being considered.
The performance of prevailing retrofit and replacement options obtained from the literature review and survey was examined computationally using ABAQUS. These examinations were accomplished by creating 7 models. For the girder that was modeled and loads were applied, findings indicated that as expected the bolted splice delivers the highest level of continuity but re-evaluation of superstructure behavior and capacity needs to considered. The link slab provides degradation protection over the pin and hanger assembly and achieves higher level of continuity at the piers as that of original pin and hanger assembly, girder capacity may need to be re-evaluated at piers and maximum positive moment location. Catcher beam system installed when pin and hanger assemblies fail to carry the design loads, and still behaves similar to the original pin and hanger assembly. The frozen pin condition has higher level of continuity as that of original pin and hanger assembly, results indicated that deterioration have continuity. Girder capacity needs to be re-evaluated at piers and maximum positive moment location.
Advisor: Daniel G. Linzell