Finite Element Modeling and Validation of Guardrail Steel Post Deflecting in Soil at Varying Embedment Depths

This paper presents finite element modeling and validation of roadside guardrail steel posts deflecting in soil. The soil model was validated for posts embedded at various depths. Prior to finite element modeling, several drop- pendulum impact tests were conducted to determine the actual response of the soil-post interaction in dynamic impacts. A decrease in the depth of the post significantly increased the deflection in soil, which complicated the modeling of the soil behavior. Finite element model of the post and soil setup was developed to capture the post-soil behavior observed in the tests. Two material models, Geological Cap and Jointed Rock, were evaluated for use in the finite element model. Additionally, Lagrangian and Smoothed Particle Hydrodynamics (SPH) methods were briefly compared to determine suitability of use. It was determined that the Jointed Rock material model is better capable of capturing the soil-post interaction in cases where the post embedment was reduced and the resulting soil deformation was large.