Physical Testing and Numerical Modeling to Develop Design Equations for Corrugated Steel Culverts under Live Loading

Abstract

This thesis investigates the structural behavior of corrugated steel culverts under live loading, through the use of field experiments and finite element modeling with the goal of developing design equations. An in-service corrugated steel arch culvert was monitored under static loading. Total station, digital image correlation, and LiDAR were found to be appropriate tools for field monitoring of culverts. Fiber optic strain sensors were also used to capture strain distributions around the culvert circumference. The experimental results revealed that bending moments could be as important as thrusts for shallow buried culverts. Another in-service arch culvert was tested under both static and dynamic loading. The distributed measurements showed that the front axle induced higher thrusts and moments than the rear axles. The asphalt pavement reduced moments by up to 38% but only reduced thrusts by 10% for this structure. To develop finite element models of corrugated steel culverts suitable for parametric studies, equivalent orthotropic properties of corrugated sheets were derived analytically. The developed expressions showed a significant improvement over those previously used in corrugated pipe finite element analysis, and guidelines for their use were then provided. Three-dimensional finite element analyses were calibrated with the experimental data from existing laboratory tests and the new field tests. The impact of various modeling choices and experimental uncertainties was studied using sensitivity analyses. The most appropriate model for circular and ellipse culverts was recommended, and used orthotropic shell elements, elastic soil properties with elastic moduli varying with depth, and tie constraints between the soil and the culvert. Finally, new design equations for thrust and moment under live loading were developed from the results of 1596 finite element analyses. The proposed thrust equations considered the relative stiffnesses between the soil and the corrugated steel culvert for the first time. Evaluations against the experimental and numerical data suggested that the new moment equations could potentially replace the current code design equations. The proposed equations were able to provide a conservative estimate of the ultimate load measured in a failure test with a 15% error while accounting for the flexural failure mechanism.