PERFORMANCE OF CONCRETE BRIDGE DECK SLABS USING ISOTROPIC AND STANDARD AASHTO PROCEDURES

This report describes the work done with alternate means of designing deck slabs by reducing the amount of reinforcement, without sacrificing the integrity of serviceability and strength of the decks, which could result in considerable cost reduction and efficient solution. The fundamental concept in the isotropic deck design is based on the "arching" effect, which takes place in the concrete deck between the short spans of the beams. As a result, the steel reinforcement experiences insignificant flexural stress. The arching effect causes the deck slab to fail in punching shear rather than flexural failure, which is the basis of the design of conventional American Association of State Highway and Transportation Officials (AASHTO) deck slabs. Therefore, shear and temperature governs the amount of reinforcement needed. The Pennsylvania Department of Transportation conducted field demonstration projects in which bridge decks were designed. They were evaluated over a five-year period. Each isotropic deck constructed had a matching counterpart (control) designed with AASHTO standards and was inspected along with those designed using empirical procedures after the first, third, and fifth year of construction. A total of seven isotropic and six conventional AASHTO decks were constructed. Evaluation of the performance of the decks is based on field monitoring reports, which give details of crack occurrence, spalling of the decks, and general condition of the bridge deck slab with actual field visit to various sites and comparing field behavior. Based on these studies, as well as on analytical studies conducted during this research, isotropic decks performed satisfactorily in accordance with the AASHTO standards. The arrangement of isotropic reinforcement is much simpler than the reinforcement pattern of AASHTO decks, resulting in easier and faster construction. Reduction in steel reinforcement in decks using isotropic design makes an attractive proposal for the state departments of transportation.

Language

  • English

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 139 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00921472
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-PA-2001-016-97-4(6),, PTI 2002-07(6),, Final Report
  • Contract Numbers: 359704, Work Order 24
  • Files: NTL, TRIS, USDOT, STATEDOT
  • Created Date: Mar 6 2002 12:00AM