Article
COMPARATIVE STUDY OF SLAB OVER PSC I GIRDER AND SEGMENTAL PSC BOX GIRDER SUPERSTRUCTURES FOR METRO VIADUCTS: A COST AND STRUCTURAL EFFICIENCY PERSPECTIVE
This Study comprehensively compares Segmental PSC Box girders and Precast PSC I-girders with in-situ slab for metro viaducts, across 19m to 31m spans. Their structural performance and economic feasibility were analyzed to determine the most cost-effective superstructure for varying span lengths. Both types were optimized for material use and serviceability, with consistent material properties. Optimal material usage (concrete, reinforcement, HT steel) were quantified and charted by varying depths. Using practical construction rates, the optimum costs and material quantities for each span was compared to guide bridge engineers in selecting optimal span arrangements. Further graphs illustrate how optimum depths, material quantities, and deflections relate to span. The study indicated that, if economy is the criterion of selection of a span arrangement, then beam and slab deck can be adopted upto a span of 22 m and thereafter, the box girder is a cheaper alternative. On the other hand, if the limitation of the depth is the criterion, then slab over PSC I- girder deck is the choice, but then the economy has to be sacrificed. Moreover, the central deflections are relatively high in the case of slab over PSC I- girder superstructure which makes it less preferable, if riding comfort is a criterion. The Box girder is a better alternative which gives lower deflections with good riding comfort and better serviceability.
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