It has been observed that thin concrete deck slabs supported by beams or girders are generally capable of carrying concentrated wheel loads far in excess of design values established by traditional methods of analysis. This capacity appears to be present even if the concrete has considerably deteriorated or a large percentage of the reinforcing steel is lost due to rusting. The usual failure made is that of punching and not flexure, hence the load-carrying capacity is defined in terms of the former. Under a concentrated wheel load, the present AASHTO Specifications, based on 2-dimensional plate bending theory, over-estimate the maximum tensile reinforcing steel stresses by a considerable margin. It has been found that the load-carrying capacity of the slab is governed by internal arching action, rather than by flexural strength. The net result is that a multiple of the absolute minimum reinforcing is being built into thin concrete deck slabs. In the presence of deicing salt, too much steel too close to the wearing surface usually results in extensive spalling of the concrete decks, leading to a marked reduction in service life. This paper covers the results of an extensive prototype investigation. Field testing of existing bridges, both composite and non-composite, deteriorated and not deteriorated, with a 445 kN (1000,000 lb.) simulated wheel load resulted in non permanent damage or upper surface cracking to the slabs. New prototype deck slabs have been built with as little as 0.2% isotropic reinforcement. The test results indicate sufficient capacity for concentrated wheel loads with steel stresses and deflection being at acceptable levels. These research findings are being incorporated into the new Ontario Highway Bridge Design Code. /Author/

Media Info

  • Media Type: Print
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: pp 171-179
  • Monograph Title: Bridge Engineering. Volume 1
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00183761
  • Record Type: Publication
  • ISBN: 0309026962
  • Files: TRIS, TRB
  • Created Date: Dec 3 1978 12:00AM