An Analytical Study on the Performance of Pre-Stressed Box Girder Bridges

In conventional reinforced concrete T-Beam Bridges spanning more than 15m, large concrete sections are required to resist imposed vehicular loads. These large sections create heavy dead weight (self weight), requiring therefore large reinforcement ratio to encounter tensile stresses and simultaneously produce excessive deflection. To reduce dead weight and control the deflection, prestressed concrete sections are found efficient from the view of economy and structural behavior. Since in curved, skew and eccentrically loaded bridge decks, torsional stresses are produced to the large extent leading to by and large unwanted shear deformations. Box girders because of having high torsional rigidity can be effective in resisting torsional stresses. Therefore, prestressed box girder bridge decks with low dead weight can be used in the construction of reasonably long span bridges (15m-40m) with better structural performance. It is therefore imperative to carry parametric study on prestressed box girder bridges with due consideration to performance, economy and structural efficiency. In this study, a two lane prestressed box girder bridge has been analyzed under class AA loading and the ideal sections have been proposed with strict deflection control in an economical way.