Abstract Manager

This paper presents the results of a comprehensive parametric study conducted to investigate the effects of backfill height, installation method, backfill soil type, and compaction level on the structural performance of three-sided culverts (TSCs) and the applied earth pressure on their top slab. Nonlinear finite element models were established for a range of TSCs configurations and were validated using full-scale field measurements of three TSCs with spans of 7.3, 10.4, and 13.5 m. The results demonstrated that embankment installation method resulted in slightly higher earth loads on the culvert top slab compared to trench installation method. Culvert installation involving dumped soil or moderately compacted sidefill along with compacted backfill on the top slab significantly increased the vertical earth loads on the top slab, and adversely affected the structural performance of TSCs and their ultimate capacity. Therefore, these compaction scenarios should not be used in the construction of TSCs. The results also revealed that the vertical arching factors (VAFs) stipulated in the Canadian Highway Bridge Design Code, CHBDC (CSA, 2019) for B1 and B2 standard installations consistently overestimated the vertical earth pressure on the top slab. On the other hand, the American Association of State and Highway Transportation, AASHTO (AASHTO LRFD, 2014) equation for trench installation underestimated VAF for B1 installation in some cases. Therefore, the equation proposed by AASHTO (AASHTO LRFD, 2014) for embankment installation was modified, and two equations are proposed to evaluate vertical earth pressures on the top slab of TSCs. The findings of this research would result in more economical, yet safe, designs of large span TSCs used as buried structures for transportation systems.