Degree Type

Thesis

Date of Award

2020

Degree Name

Doctor of Philosophy

Department

Civil, Construction, and Environmental Engineering

Major

Civil Engineering (Structural Engineering)

First Advisor

Behrouz Shafei-pamsari

Abstract

Bridge management systems are primarily used to predict the future condition state of deteriorating bridges and plan for maintenance and repair actions that ensure the long-term safety and performance of bridges. The deterioration models employed in the current bridge management systems have been developed using Markov processes, the accuracy of which greatly depends on the transition probabilities generated based on a combination of inspection data and expert elicitation. There are, however, notable limitations in both sources of information, including the absence of long-term inspection data and the errors that can exist in expert opinions. To address such limitations, the main motivation of this dissertation is to incorporate the physics-based models developed for the study of deterioration process into the current bridge management systems. Since the simulation of the deterioration process in RC structures is often considered a tedious task, a holistic investigation is performed in this dissertation to understand the capabilities of finite element (FE) and cellular automaton (CA) frameworks for modeling the diffusion process and estimating the chloride content and carbonation depth. The impact of environmental factors, such as temperature, humidity, and precipitation, on the crack width and time duration to reach the durability thresholds is quantified. In addition to the investigation of corrosion initiation, a detailed framework is developed to link the corrosion process to the availability of oxygen at the cathodic region, which is proven to be the governing factor in the second stage of corrosion, i.e., corrosion propagation. A simulation-based probabilistic approach is then employed to investigate the uncertainties that inherently exist in the assumptions made for various oxygen diffusion parameters, polarization variables, and structural details, especially to predict the crack width, as a threshold for both durability and serviceability assessment purposes. While the existing bridge management systems deliver a range of capabilities for the management of bridges under normal operational conditions, they lacked in considering the consequences of sudden extreme events in a systematic way. To address this shortcoming, a risk-based approach is developed in this dissertation that not only takes into account the site-specific aging mechanisms and extreme events at the same time, but also accommodates the spatial and temporal randomness originated from them. The outcome of this dissertation is expected to pave the way to choose and employ appropriate physics-based models for bridge management systems that deliver reliable predictions of the deterioration process of RC bridges. This contributes to improving the life-cycle performance and cost assessments conducted by transportation agencies.

DOI

https://doi.org/10.31274/etd-20210114-73

Copyright Owner

Dena Khatami

Language

en

File Format

application/pdf

File Size

189 pages

Available for download on Friday, January 07, 2022

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