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IASS-SLTE Symposium 2014: Shells, Membranes and Spatial Structures: Footprints

IASS Symposium 2014

SESSION: General 3: Case Studies

Troja Bridge in Prague - steel structure and prestressed network of tendons

< Table of Contents for General 3: Case Studies
  • Proceedings Name: IASS-SLTE Symposium 2014: Shells, Membranes and Spatial Structures: Footprints
  • ISSN: (Electronic Version) 2518-6582
  • Session: General 3: Case Studies
  • Title: Troja Bridge in Prague - steel structure and prestressed network of tendons
  • Author(s): Vladimir JANATA, Dalibor GREGOR
  • Keywords: Bowstring-arch type bridge; network type web; prestressed hangers; strain gauges
The new city Prague Bridge which crosses the Vltava River and will serve for trams, cars in four traffic lanes and pedestrians between districts Troja and Holesovice is nearly finished now. The deck is 36m wide including the walkways. The bridge of the main span 200,4m is a simply supported bowstring-arch type bridge with two longitudinal prestressed steel-concrete chords and two twins of inclined network type webs of hangers. The steel arch spanning 200,4m with the rise of 20m only has flat pentagonal box cross section with varying width and height. The structural height of the box is 1,3m only and it is 7m wide in the middle of the span. The arch is divided into two “legs” on both sides, which are of tetragonal box cross-section. The „legs”, are connected to the steel core of the arch chords through four base sections filled with the concrete. There are 200 hangers of 520MPa steel grade with dimension of the thread M76 – M105 in the bridge network. Hangers are created by certified system which consists of solid bars with rolled threads, turnbuckles, forks, pins, and lock covers. Hangers were installed and activated first to avoid non-linear component of stiffness. Than prestressing was realized mostly by own weight of the structure released from the temporary supports in the river. The installation and prestressing procedure of the hangers was carried out symmetrically across the longitudinal and transverse axes of the bridge in order to ensure correct shape of the arch. The prestressing procedure was carried out on the basis of matrix of mutual interference of individual hangers calculated on partial models comprising only hangers present in the structure in appropriate phase. The forces in the hangers are measured by strain gauges. Measuring system enables to follow on-line all forces in actually installed hangers on the bridge. The second stage of prestressing of hangers was carried out after releasing the deck from the supports in the river to optimise internal forces in the arch and to avoid theoretical compression forces in hangers in any future load combination. At the end, after installing of all permanent loads, the frequency measurement of all hangers will be carried out. The measured frequencies will be compared with ones measured in future within of regular inspection of the bridge.

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