Strengthening Existing Non-Composite Steel Bridge Girders Using Post-Installed Shear Connectors

Gunup Kwon, Brent Hungerford, Hulya Kayir, Brad Schaap, Young Kyu Ju, Richard Klingner, and Michael Engelhardt


This study investigated methods to strengthen existing non-composite steel bridge girders by the development of composite action between the steel girder and concrete slab. More specifically, the objective of this study was to identify structurally efficient and practical ways to post-install shear connectors in existing bridges. Various types of post-installed shear connection methods were tested under static, high-cycle fatigue, and low-cycle fatigue loads using a direct-shear test setup. Based on the results of single-shear connector tests, full-scale beam tests were performed under static load to evaluate system performance of the beams retrofitted for partial composite action with post-installed shear connectors.

The results of this study clearly demonstrate that the strength and stiffness of existing non-composite steel bridge girders can be increased significantly by post-installing shear connectors. Development of composite action between the existing steel girder and concrete slab through the installation of post-installed shear connectors appears to be a structurally efficient and cost-effective approach to retrofit existing bridges. The addition of postinstalled shear connectors can increase the load capacity of existing steel girders on the order of 40 to 50%. Preliminary guidelines are provided.

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