Prestressed reinforced concrete (PRC) highway bridges are subjected to deterioration that requires strengthening of an existing structure to restore or add capacity for the bridge to remain functional. A common method of external strengthening is the addition of fiber reinforced polymers (FRP). Limited studies are available to address the deflection analysis of FRP externally strengthened PRC girders with harped strands. A nonlinear sectional analysis, simplified by implementing a trilinear moment-curvature response, is used to obtain closed form analytical deflection expressions for simply supported girders subjected to different loading conditions. From the trilinear moment-curvature response, the procedure derives closed form deflection equations using the moment-area theorem. In deriving the equations, closed form analytical expressions are obtained for uncracked, post-cracked and post yielded regions. The developed procedure is used to compare the present analytical results to some available experimental results reproducing excellent correlation. Furthermore, the predictions of other deflection equations proposed earlier in the literature such as Branson and Bischoff effective moment of inertia expressions are unfavorabley compared to the same experimental results. On the other hand, the results of a newly proposed set of equations for the effective moment of inertia after cracking of the PRC-FRP girders, developed for straight strands are shown to closely match the experimental load-deflection response.