Strengthening continuous steel girder bridges with post-installed shear connectors and inelastic moment redistribution

Many continuous steel bridges constructed prior to the 1970s have floor systems consisting of a non-composite concrete deck over steel beams with no shear connectors. While many of these bridges are still in good condition, the structures may not satisfy current load requirements and thus may need to be strengthened or replaced to avoid load-posting and to maintain structural safety. One potentially economical method of extending the service life of such bridges is to post-install adhesive anchor shear connectors to create composite action between the existing steel beams and concrete deck. This is efficient in regions dominated by positive flexural demands where the concrete deck is in compression. Inelastic moment redistribution away from the interior pier sections can be considered to address strength deficiencies in these regions, which are dominated by negative flexural demands. This dissertation explores this method of strengthening continuous non-composite steel girder bridges. Of particular interest is the “shakedown” behavior of partially composite strengthened girders under large repeated loads requiring moment redistribution. These concepts are commonly referred to as “autostress” design. After conducting preliminary studies on the feasibility of this strengthening method for typical bridges in the state of Texas, an extensive large-scale experimental program was conducted in conjunction with finite element modeling. The results of the testing and modeling are discussed in detail. Design recommendations and a design example are also provided.