Economical design for long-span soil – metal structures

Abstract

Soil – metal structures consisting of metal conduits covered with soil have been used extensively for short-span bridges. Recently, some designers ventured into utilizing them for longer spans with shallow soil cover which has led to some failures. Long-span soil – metal structures are often designed with transverse stiffeners attached to the metal structure. Another approach is the use of a reinforced-soil system in which the surrounding soil is reinforced and the metal conduit is tied into the soil. In this paper, a three-dimensional analysis of long-span soil – metal structures is carried out using these two approaches. The analysis is verified and substantiated by results from laboratory models. The structural responses from the two designs show that the latter design approach leads to a more economical structure. A design example based on the Cheese Factory Bridge built in Ontario in 1984 is presented. Key words: bridges, design, long span, reinforced soil, soil – metal structures, structural engineering, three-dimensional analysis.