Numerical modeling of the seismic racking behavior of box culverts in dry cohesionless soils.

In this study, dynamic behavior and lateral earth pressures on box shaped culverts buried in dry cohesionless soils were investigated through validated numerical analyses. Two dimensional plane strain finite difference models of 4m-high box culverts with different wall flexibilities were analyzed using FLAC-2D Finite Difference Code. The effect of relative flexibility on the dynamic racking displacements of the structure was investigated by modifying dynamic shear modulus of the cohesionless soil and structural attributes of the models. Shear strains, horizontal accelerations and wall deformations as well as lateral dynamic earth pressures at various points on the culvert were investigated through the numerical analyses. Results of the numerical analyses were validated with those of a previous centrifuge modeling study. Racking deformations of the numerical culvert models are found to be in agreement with the centrifuge test data. Dynamic lateral pressures acting on the side walls increase as the wall flexibility ratio decreases. Dynamic force on the sidewalls of the box culvert may reach up to 2.8 times the at-rest lateral earth load for the stiff prototype, whereas for the flexible prototype, this value is only 1.6 times the static earth load. [ABSTRACT FROM AUTHOR]