First Advisor

David Yang

Term of Graduation

January 2024

Date of Publication

1-1-2023

Document Type

Thesis

Language

English

Subjects

Finite Element Analysis, Live Load Effect, RC Box Culverts, Soil-Culvert Interaction, Structural Frame Model, Uncertainty Quantification

Physical Description

1 online resource ( pages)

Abstract

Although buried and mostly invisible to the traveling public, bridge-sized culverts (i.e., culverts with span around or longer than 20 ft) account for a large proportion of state-managed bridges. As per Oregon Department of Transportation inventory, there are approximately 35,000 culverts in the state highway system. Among them, 10,862 are in poor conditions and need to be analyzed for load rating purposes. The prediction and understanding of live load effects in culverts are crucial to the design, evaluation, and life-cycle maintenance of culverts. These live load effects include maximum bending moments and shear forces at different critical cross sections. This study focuses on the uncertainty quantification of live load effects in buried RC box culverts. The uncertainties under investigation include axle weight uncertainty within a 75-year period and model uncertainty due to the simplified load distribution model used in the current design specifications. For axle weight induced uncertainties, Monte Carlo simulation and extreme value theory are employed to calibrate live load projections, recognizing the inherent variability and uncertainty associated with long-term forecasting. To quantify the uncertainty related to the load distribution model, 680 three-dimensional finite element (FE) models of 34 culverts with 2 backfill depths (4ft and 8ft) and two types of axle load (single and tandem) are created to serve as benchmarks for different live load effects in culverts, capturing diverse geometries, material properties, and loading conditions. Concurrently, simplified two-dimensional structural frame models are established to estimate live load effects following design specifications. Live load effects obtained using both types of models are compared and analyzed in detail. Based on the comparison, the epistemic uncertainty related to the load distribution model is quantified. The findings from this study are instrumental to the reliability-based calibration of load factors and the revision of load distribution models used for culvert design and rating.

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Available for download on Saturday, February 01, 2025

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