Assessment of Dynamic Load Allowance for Buried Culverts

Abstract

In the past, research on buried culverts has focused on looking at live load distribution through soil onto buried culverts and given little attention to the dynamic amplification of moving loads. The few studies that looked at the dynamic amplification of buried culverts idealized the load-soilculvert problem using a plane-strain assumption. Under such conditions, the finite area axle loads are erroneously modeled as strip loads acting over the entire width of the culvert. In this study, the plane-strain assumption is removed and the load-soil-culvert system is modeled and analyzed a three-dimensional problem. Dynamic load allowance (DAF) was determined from field measurements, two-dimensional finite element method (2-D FEM), and three-dimensional finite element method (3-D FEM). The 2-D and 3-D FEM models resulted in an average DAF of 1.099 and 1.048, respectively. The average DAF calculated from field measurements and the American Association of State Highway and Transportation Officials (AASHTO) recommended formula are 0.963 and 1.295, respectively. Overall, the AASHTO DAFs are the highest and the field DAFs are the lowest. The plain strain assumption adopted in the 2-D FEM models resulted in DAF values that are higher than the 3-D FEM and field evaluated DAFs. The DAF calculated from threedimensional models is the closest to the field measured DAFs.