Field measurements of 22 in-service flexible box culverts showedthat the in-place geometries of these in-service structures may vary from their theoretical geometries. Because the simplified design method (sdm) for box culverts, developed in the early 1980s, was based on small-strain nonlinear finite element analyses (fem) of box culverts with theoretical "design" geometries, it was necessary to evaluate how structural deformations would affect the induced bending moments that govern box culvert design. Additional fem studies of deformed and undeformed box culverts show that the current sdm methodology may slightly underestimate the design bending moments for flexib^e box culverts with installed geometries that differ significantly from their theoretical undeformed geometries. Design bending moments were found to be underestimated by as much as 20% for worst-case deformation conditions with shallow crown cover depths. An appropriate minor modification of the sdm methodology is thus proposed. This paper appears in transportation research record no. 1231, Analysis, design, and behavior of underground culverts.
Abstract