Graduation Semester and Year
2022
Language
English
Document Type
Thesis
Degree Name
Master of Science in Civil Engineering
Department
Civil Engineering
First Advisor
Nur Yazadani
Abstract
The ASCE infrastructure report card indicated that about 42% of the nation’s bridges are over 50 years old, and 7.5% of the bridges are structurally deficient. The 61-year-old St. Francis bridge over IH-30 is one of the Texas Department of Transportation (TxDOT) bridges that exhibit significant deterioration in the superstructure, including potholes and delamination in the deck. The bridge was load posted to 28,000 lb. limit and has substandard vertical and horizontal clearances to the bottom chord of the beams and supporting piers, respectively, which creates a high risk for vehicle impact. In 2017, an over-height truck struck the northbound bridge deck and girder and caused significant damage. In addition, the unprotected piers were unable to withstand vehicular impact loading. The various deficiencies had to be rectified, either through reconstruction or retrofitting, to meet current code requirements. The restoration alternatives included only raising, only retrofitting, and both raising and retrofitting. Eight retrofitting solutions were then analyzed to enhance the deck, girder, and combined performance. For replacement, the existing bridge would have to be dismantled, and a new bridge meeting the current code requirement would be constructed at the footprint of the existing bridge. Pier protection was also considered to reduce the possibility of pier collision, owing to insufficient horizontal clearance. It was vital to identify the most effective option among these alternatives before selecting and implementing the most appropriate one. Accordingly, the current study developed a decision tree to make an informed decision on whether to retrofit or replace structurally deficient bridges.v Benefit-Cost Analysis (BCA) was performed, which required the assessment of associated Life Cycle Cost (LCC) and potential advantages from an improved measure or alternative. The General Condition Rating (GCR), LCCA, and risk utilities were then independently assessed and merged into a utility function to calculate the overall benefits. Finally, the Benefit Cost Ratio (BCR) was calculated by dividing the action costs by the benefits. Moreover, the improved load rating from diverse retrofitting options and carbon footprint effects for all the alternatives were also taken into consideration for decision-making purposes. The proposed methodology can be used to make cost-effective decisions for highway bridges with similar deficiencies.
Keywords
Life Cycle Cost Analysis(LCCA), Benefit-Cost Analysis (BCA), Benefit Cost Ratio (BCR), Structurally deficient bridges, Retrofitting, Rehabilitation, Impact damage, Carbon-footprints, Pier-protection, Decision tree
Disciplines
Civil and Environmental Engineering | Civil Engineering | Engineering
License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.
Recommended Citation
Abir, Md Farhan, "DEVELOPMENT OF A DECESION TREE TO REHABILITATE OR REPLACE THE ST. FRANCIS BRIDGE OVER IH-30" (2022). Civil Engineering Theses. 91.
https://mavmatrix.uta.edu/civilengineering_theses/91
Comments
Degree granted by The University of Texas at Arlington