Ultimate capacity of large-span soil-steel structures

Abstract

The ultimate limit states provided by current design codes and standards were based on full-scale field and laboratory tests performed on soil-steel structures (SSS) of spans less than 10.0 m. Recently, the spans of SSS have increased up to 32.4 m with the tendency to exceed this record. The ultimate capacity of SSS utilizing the deepest corrugation profile, i.e., 237 mm depth and 500 mm pitch, has not been yet investigated under earth and truck loading. The current study evaluates the ultimate capacity of the world’s largest-span SSS with 32.4 m span and 9.57 m rise, using three-dimensional (3D) nonlinear finite element simulation. The investigation covered both the maximum backfill height and ultimate truck loading conditions. The 3D finite element modelling technique under ultimate loading was validated by full-scale test measurements of 10.0 m span soil-steel structure subjected to tandem axle loading. The critical straining actions obtained from the steel structure at ultimate condition was used to evaluate the ultimate limit states provided by the Canadian Highway Bridge Design Code (CHBDC, 2019) and AASHTO (AASHTO LRFD, 2019). The results revealed that the ultimate capacity of the SSS was reached without conforming to all ultimate bounds provided by the current design codes. Finally, a limit state function was proposed to account for the structure instability that may occur to the steel structure under ultimate loading condition. The proposed function successfully predicted failure in the steel structure under all cases considered in the current analysis before failure occurred in the numerical results.