Reliability of concrete box culverts designed for vertical loads

The design vertical loads on box culverts under embankments are commonly calculated using the soil-structure interaction factors (Fe) recommended by the American Society of Highway and Transportation Officials (AASHTO). Non-linear finite element analyses were used to update Fe given by AASHTO by considering the effects of backfill height, culvert stiffness, backfill material stiffness, backfill compaction, and the rigidity of the layer on which the culvert rests. A simplified reliability analysis was performed to determine the adequacy of safety level in AASHTO load resistance factor design (LRFD) code specifications.