Graduation Semester and Year

2018

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Nur Yazdani

Abstract

Fire events and impact damage on bridges are few of the least understood of common extreme events. Bridge infrastructures that are subjected to hazards such as fire or impact from over height vehicle can catastrophically collapse or be heavily damaged. External wrapping of damaged concrete bridge components with Fiber Reinforced Polymer (FRP) laminates has been used as a strengthening technique for these bridges. Two such in-service bridges, one of which was fire damaged and the other impact damaged, both aged more than 50 years old in Irving, Texas, were selected for this study. The damaged beams of the concrete bridges were subsequently repaired and strengthened with carbon FRP (CFRP) laminates. The girders were instrumented with strain gauges and displacement transducers, and a non-destructive live load test was carried out. The results from the load test were used to evaluate the performance and determine the lateral flexural load distribution. The strengthened girder exhibited a lower midspan deflection and lower strain than a similar representative undamaged girder. FE models were prepared and calibrated using the experimental results. Fire model using a Fire Dynamics Simulator (FDS) and heat transfer analysis was used to accurately predict the post-fire material properties of concrete to calibrate the FE model for fire-damaged bridge. It was observed that the modulus of elasticity of the fire damaged section of the bridge was reduced by 20% to 75% in different sections of the bridge. A calibrated FE model for the impact damaged bridge was also able to mirror the experimental performance of the bridge. Load distribution characteristics of the bridge were studied and compared with AASHTO LRFD distribution factors for moment.

Keywords

Bridge fire, Load testing, Impact damage, Fire dynamics simulator, CFRP laminate, FRP strengthening, Finite element modeling

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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