Bridge strengthening for 517 t heavy vehicle load using external prestressing

Whangamarino River bridge, located on State Highway 1, comprises a 3-span simply supported, 40 m long deck with maximum 13.38 m span length, carrying two traffic lanes over the Whangamarino river. The bridge was designed to the Transit NZ HN/HO loading standard of 1981, requiring upgrading to carry a series of heavy load platform (HLP) loads. The critical HLP loading was assessed as being the 377 tonne turbine producing a gross vehicle mass of 517 tonne. An assessment of the structural elements in accordance with the Transit NZ Bridge Manual was undertaken to determine the rating and capacity to safely carry the HLP load. The assessment indicated that the critical elements were the deck planks and the pier bearing beam, requiring substantial strengthening. Alternative strengthening options were considered, the preferred option adopted being the use of external post-tensioning to strengthen both structural elements as follows: strengthening each deck DHC beam using straight external tendons and anchorages attached to the beam soffit; and strengthening the pier cross-beam using deviated external tendons in the span with anchorages attached to the beam sides. This paper presents the findings of the assessment of key bridge elements and alternative strengthening options, and illustrates the strengthening method adopted using external prestressing. (a) For the covering entry of this conference, please see ITRD abstract no. E214936.


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  • Accession Number: 01054986
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ITRD, ATRI
  • Created Date: Aug 6 2007 2:12PM