Ministries and departments of transportation are working to undertake assessments of deteriorated metal culverts. To assist with these assessments by developing rational methods of classifying culverts, to select those requiring replacement or repair, the current thesis studied the effects of metal corrosion and backfill erosion on culvert stability. Finite element calculations were used to explain how stability is jeopardized by two forms of deterioration, both material failure (yield in the steel) and geometrical nonlinearity (bucking failure). The stability assessments are presented for structures designed using limit states design procedures in the Canadian Highway Bridge Design Code and the LRFD Bridge Design Code of the American Association of State Highway and Transportation Officials. It was found that yield in culverts in intact ground is proportional to plate thickness (thrust and moment are not affected). Buckling strength changes as corrosion occurs, but does not become critical in structures supported by good quality backfill (without erosion). Surprisingly, thrusts decrease when erosion develops adjacent to the culvert, and this implies that factor of safety against yield is increased. However, substantial decreases in buckling strength occur, and elastic instability can then become the critical performance limit after erosion. Three dimensional finite element analysis indicates that local buckling can develop before global buckling, for new structures featuring thin plates, or for thicker structures after corrosion. This form of elastic instability may not be safely estimated using current culvert buckling equations which consider global buckling. Local buckling results were not effectively estimated using the Bryn’s equation (the conventional method used for stiffened plate structures); therefore a preliminary design equation for assessment of local buckling is provided. After verifying the results obtained from this thesis with physical experiments, these findings can provide practitioners with useful evaluation tools for a quantitative assessment to the stability of buried culverts subjected to these two different kinds of deterioration (corrosion and erosion) in order to augment engineering experience or judgment, which is the primary tool currently being used. Moreover, the current study helps future experimental and numerical studies by investigating various significant deterioration scenarios, and the impacts of these scenarios. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-10-08 12:56:13.218

The goal of this thesis is to develop more effective quantitative procedures to evaluate the stability of deteriorated metal culverts and a better understanding of the deteriorated culverts' behaviour through non-destructive testing, full scale experiments and numerical analyses. First, three design cases were examined using numerical analysis to study the effects of corrosion, burial depth and staged construction on the capacity of deteriorated steel culverts. Then, a method to measure the remaining wall thickness of two 1.8 m diameter corroded metal culverts using ultrasonic device was developed. Both culverts were then buried in the test pit at Queen's University and tested under nominal and working vehicle loads at 0.9m cover and 0.6m cover. The more heavily corroded structure (CSP1) was tested up to its ultimate limit state, inducing local bending across the crown, as well as local buckling of the remnants of the corrugated steel wall between perforations at the haunches. The results suggest that the single axle pads interact to influence the culvert's behaviour despite the shallow cover used in these experiments. CSP1 was able to carry the working load and did not fail until reaching 340 kN, which was equal to 90% of the fully factored load. The experiment suggests that less deteriorated metal culverts (as compared to CSP1) may have the required capacity. Two finite element packages, CANDE and ABAQUS, were used to perform the numerical investigation and the AASHTO and CHBDC approaches were then used to calculate the thrust force in the culverts. Although the numerical analysis produced conservative values for the thrust forces, it failed to capture the non-linear behaviour of both specimens in the experiments. Both the AASHTO and the CHBDC approaches produced unconservative thrust forces compared to experimental results while numerical analysis using Moore's spreading factor produced the most conservative results in terms of thrust. The analysis suggests that CANDE could be used to predict thrust forces in less deteriorated metal culverts. A procedure to assess the stability of deteriorated corrugated metal culverts based on quantitative data was developed using the numerical analysis and experimental results. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-01-30 12:56:17.945

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