Graphical Assessment for Span Ranges of PSC Girder Bridges

Abstract

Although the prestressed concrete (PSC) girder bridge is known to be more economical than other types of bridges in short and medium spans, a longer span has also been achieved by applying several strategies. This paper presents a systematic procedure that can be used to assess the effects of these strategies on the span. The proposed scheme adopts a graphical approach that represents a relationship between the number of prestressing tendons and the span and is derived on the basis of stress assessment equations of the girder at each stage of fabrication and in service. A quantitative evaluation for the extension of the span is performed by adopting a sample bridge. A number of advantages of the proposed scheme are apparently shown for determining why and how each strategy contributes to the span extension and for suggesting further improvement for a longer span. The results imply that increasing the strength of the girder, making the girders continuous, multistage prestressing, and the decked PSC girder are very effective.