Parametric Investigation of Factors Influencing the Dynamic Response of Buried Reinforced Concrete Culverts

In the current practice of bridge engineering, structures are designed and evaluated using static loads. In order to account for the dynamic nature of the true loading condition, static vehicle loads are increased by a dynamic amplification factor (DAF). The DAF has been widely studied for conventional bridges and has been found to be a function of vehicle forcing frequency and the fundamental frequency of the bridge. As a simplification, many design codes determine the DAF factor based on common bridge characteristics, namely the span length. The AASHTO LRFD Bridge Design Specifications simply use a single, conservative value for conventional bridge types. In the case of buried bridge structures, the dynamic behavior is complicated by the soil layer present between the asphalt and structure. In order to accurately determine the response of buried box culverts in a dynamic loading scenario, the interaction between the asphalt, soil, and structure must be taken into account. Through a parametric finite element analysis, four aspects of the asphalt-soil-structure system are examined in order to determine the factors which most influence its dynamic response. Parameters under scrutiny are depth of fill, fill stiffness, culvert span length, and culvert flexural rigidity. This research shows that fill depth and slab thickness are most influential in determining the dynamic amplification factor. However, span length and soil stiffness do have some effect.