Soil-Steel Structure Design by the 1979 Ontario Highway Bridge Design Code, a Historical Perspective

The term ‘soil-steel structure’ was coined during the development of the 1st edition of the Ontario Highway Bridge Design Code (Ontario Highway Bridge Design Code, Ministry of Transportation and Communications, Downsview, Ontario, 1979) to denote structures having spans greater than or equal to 3.0 m and comprised of corrugated steel plates and engineered soil, designed and constructed to induce a beneficial interaction between the two materials. Before this, these structures were known by various names, such as buried structures and corrugated metal structures. Although these structures had been in existence since the end of the Nineteenth Century, their design had been entirely empirical. The OHBDC was the first bridge design code in the world to provide not only ‘rational’ design provisions for these structures, but also prescribe procedures for their construction. It is noted that these economical alternatives to conventional bridges were more prone to distress and failures than other bridges. The main cause for their failure was errors in their construction. This paper, besides providing a historical account of the design and construction provisions for soil-steel structures introduced by the 1st edition of the OHBDC, also gives an account of some recent developments in these structures.