Browsing by Author "Hajjar, Jerome F"

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    Live Load Stresses in Steel Curved Girder Bridges
    (2001-09-01) Hajjar, Jerome F; Ray, Joel D; Wyffels, Tina; Carlsson, Magnus
    Their initial curvature make steel-cured girder bridges more susceptible to lateral-torsional bucking during construction. Critical in assessing the strength and fatigue life of the bridge components, predicting stresses in the main girders and the crossframes proves more comples than in straight bridges. In this project, researchers investigated the correlation between measured and computed results in a two-span, four-girder, continuous composite steel curved girder bridge with skew supports. A previous phase involved computing the stresses through a linear elastic grillage finite element computer project and comparing the results with a typical third-party curved girder analysis program. The project's second phase further investigated the correlation between measured and computed stresses by running two additional live load tests on the bridge. This report summarizes research to investigate the behavior of the curved girder bridge system through all phases of construction, as well as to a series of live load field tests. In addition, researchers investigated the effects of change in temperature on the bridge behavior and tracked any changes in behavior of the bridge system over time and under service load conditions.
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    Repair of Fatigued Steel Bridge Girders with Carbon Fiber Strips
    (2003-12-01) Shield, Carol K; Hajjar, Jerome F; Nozaka, Katsuyoshi
    This report investigates a method of repairing fatigued steel bridge girders using carbon fiber reinforced polymer (CFRP) strips. This type of repair would be used to prevent the propagation of cracks which could lead to failure of the bridge girders. The main advantages of using CFRP are it is lightweight and durable, resulting in ease of handling and maintenance. Therefore, it would not require the closing of traffic on the bridge during rehabilitation. Effective bond length was determined by a series of experimental tests with actual materials, as well as through the use of analytical equations. Finally, tests were conducted on full-scale cracked girders; the application of the CFRP strips to the steel girders resulted in significant strain reduction, except in the case of small cracks where it was difficult to clearly identify the benefits.