Semester

Spring

Date of Graduation

2016

Document Type

Problem/Project Report

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Hota V.S. GangaRao

Committee Co-Chair

Udaya Halabe

Committee Member

Mark Skidmore

Abstract

The West Virginia Department of Transportation State Rail Authority sponsored a study to evaluate the condition of the railroad bridges on the Dailey Branch in Elkins, WV. The evaluations included field inspections, load rating, load testing, and a repair plan. A total of 2 steel bridges and 3 timber bridges were part of the study. The repair plan focused on identifying deteriorated timber bridge members for potential Glass Fiber Reinforced Polymer (GFRP) wrap repair. Information on dimensions and deterioration was gathered through field inspections. A timber specialist determined the species and grade of the timber bridges, finding most members to be Select Structural lumber of Southern Pine species. A preliminary analysis was performed to ensure that the bridges would withstand a hi-rail dump truck and a locomotive during load testing. A total of 76 strain gages were installed on all 5 bridges to record bending, shear, and axial compression data. Steel Bridge 1.4 is a 2 span steel through-girder bridge with spans of roughly 98 feet, and the measured field strains correlated well to those predicted through load rating analysis. The other steel bridge, Bridge 5.8, had field measurements of about 1.5 times lower than theoretical predictions, likely due to the contribution of the track structure on the 20’ span. The field measured strains for the timber bridges were always less than theory for bending and shear, typically by a factor of about 2, due to the extra stiffness added through composite action between the ties and track together with the stringers, as evident through the shifting of the neutral axis. Field compression strains in the posts were typically higher than predicted, except for two cases, which are most likely due to the section losses in the instrumented posts and uneven bearing conditions. All bridges were load rated using AREMA standard Cooper E 80, a 286K freight railcar, and GP 38 locomotive with the analysis assumptions verified during the field load testing process. Under normal rating conditions, the bridges do not meet Cooper E 80 rating, but they can safely carry all other equipment. Recommendations for maintenance were made for the steel bridges. A cost-benefit analysis on timber bridge repair was used to recommend stringers to be replaced, and substructure members to be wrapped with GFRP, and filled with resin and bulk filler.

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