DURABILITY DESIGN: APPLYING DATA FROM MATERIALS RESEARCH AND DETERIORATED STRUCTURES

Steel and masonry bridges, with reasonable maintenance, have demonstrated design lives of well over 100 years. Traditional designs still used for concrete bridges are showing severe durability problems in 20 to 40 years, when exposed to marine and deicing salt. To remedy this, a quantitative methodology must be developed for durability design for concrete. This can use a similar approach to structural design with actions related to environmental conditions and 'resistance' related to material characteristics. Ingress rates for chlorides must be calculated. A substantial factor of safety, to cover variability and uncertainty in materials and construction, will also be required. The fundamental research and field data required for this are becoming available for incorporation in models of deterioration processes and for the design of major projects. Improved performance requires changes in design, detailing and site practice to reduce the severity of exposure to chlorides and the variability of site concrete. Improved materials alone will not solve the problems. (A) For the covering abstract see IRRD 882313.