Highway bridges in the United States are frequently damaged by overheight vehicle collisions. The increasing number of prestressed concrete bridges indicates that the probability of such bridges being impacted by overheight vehicles has increased. This thesis, sponsored by the Virginia Center for Transportation Innovation and Research (VCTIR), investigated three repair techniques for impact damaged prestressed bridge girders: strand splices, fiber reinforced polymer (FRP) overlays, and fabric reinforced cementitious matrix (FRCM) overlays. The flexural strength of four AASHTO Type III girders, three of which were intentionally damaged and repaired, was evaluated. Six experimental tests were performed on these girders: one undamaged girder test and five repair method tests. Nonlinear beam models and three-dimensional finite element (FE) models were created to predict the behavior of the beams under flexural testing, and subsequently validated and calibrated to experimental test data. The very good accuracy of the beam models indicated that they can be used alone for the performance assessment of damaged and repaired girders. Of course, the analyst must always be aware of the fact that a beam model cannot explicitly account for potentially crucial effects such as diagonal cracking. A direct comparison between repair methods was made by creating analytical models of a prototype girder setup. FRP overlays were seen to restore the most strength, while strand splices were seen to restore the most ductility. From observation, combining repair methods resulted in an additive effect on strength, but the deformation at onset of failure will be governed by the less ductile method. / Master of Science

This study is part of a VDOT sponsored project focusing on repair techniques for impact damaged prestressed bridge girders. The investigation included evaluation of the repair installation and flexural strength of four AASHTO Type III girders that were intentionally damaged and repaired. In addition, nonlinear finite element modeling was used to aid in the development of design protocols for each repair method. This report discusses two of the three repair techniques. Three Master of Science students report on the project results: Justin Liesen, Mark Jones, and Michael Gangi. Liesen and Jones (2015) had responsibility for the installation and testing of the repaired girders and Gangi (2015) performed the finite element modeling of the girders. Three repair methods were identified for experimental investigation: strand splice, bonded FRP, and FRCM. During this investigation the repair methods were evaluated by conducting six flexural tests on four AASHTO Type III girders. Flexural tests were conducted instead of shear tests because typical impact damage from overheight vehicles occurs around the mid-span and flexural strength dominated region of bridge girders. The cracking and failure moments for each test were evaluated and compared to predictions of the girder's behavior using AASHTO calculations, a moment-curvature diagram, and non-linear finite element modeling. / Master of Science