A parametric study of dynamic amplification factors for reinforced concrete box culverts using three-dimensional finite element analysis

Abstract

Load rating is a common practice worldwide. It is used to evaluate the condition and strength of a bridge or culvert. When load ratings produce a rating factor less than one, bridges and culverts must often be posted to limit the speed and/or weight of vehicles traveling over them. Such restrictions significantly limit or prevent access and are costly. To evaluate the dynamic response of a structure to be used in the rating factor equation, a dynamic amplification factor (DAF) is applied to the response of the structure to an equivalent static load. American Association of State Highway and Transportation Officials (AASHTO) guidelines specify the DAF for culverts as a function of fill depth only. Studies have shown that AASHTO calculated DAFs can be overly conservative in many cases and can result in the unnecessary posting of culverts. Though this issue is relatively widely recognized, a better alternative for determining DAF has yet to be proposed and accepted. ☐ In this work, DAFs were calculated from the static and dynamic responses of 83 unique models using three-dimensional (3D) finite element analysis (FEA) in Abaqus ® (Dassault Systemes Simulia Corp. 2014). Four parameters were chosen and varied across three values to assess their effect on the DAF. The parameters and values are as follows: span lengths of 4, 8 and 12 meters; asphalt pavement thicknesses of 0.1016, 0.1524, and 0.2032 meters; soil fill depths of 0, 1.2192, and 2.4384 meters; and soil elastic moduli of 50, 120 and 190 MPa. Two models were evaluated with intermediate fill depths of 0.6096 meters and 1.8288 meters. The results of this study indicate that the DAF is most related to fill depth when compared to the other parameters. However, contrary to AASHTO’s guidelines, the DAF increases with increasing fill depth.