Bridge structures in urban environment often need to negotiate very tight radius curves with medium range spans due to alignment constraints. The commonly adopted solution of concrete box beam structures with inclined webs and narrow column heads leads to reduced transverse spacing between bearings, which poses stability problems in simply supported span structures. Eccentric live loads, centrifugal loads, wind loads and railway nosing loads further aggravate the stability problem. There are various ways to achieve stability of simply supported spans with tight curves viz. increasing the structure weight at supports to achieve more downward bearing loads, providing holding down (tension) bearing system, increasing the spacing of bearings by adding collars etc. This paper investigates an approach to achieve stability of simply supported spans by post stitching the adjacent spans to form a partial continuous structure along with introducing offsets to the bearings. This concept has been driven by the need to standardize the span-by-span erection method in precast segmental bridges. It allows a uniform seamless viaduct for the entire alignment and the variations in structural detailing are minimised. Salient design features of a real life example of a precast segmental rail viaduct, which has been designed and constructed using the approach discussed in this paper, are provided and the practical aspects are discussed after the conceptual study part of the paper. For the covering abstract see IRRD E104152.

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  • Corporate Authors:

    Thomas Telford Limited

    London,   United Kingdom 
  • Publication Date: 1999


  • English

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  • Accession Number: 00788376
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-7277-2841-5
  • Files: ITRD
  • Created Date: Mar 3 2000 12:00AM