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. Ganga Rao

Committee Co-Chair

Radhey Sharma

Committee Member

Mark L. Skidmore

Abstract

In this report, the two steel bridges studied are bridges 1.4 and 5.8 on Dailey Branch line, part of the West Virginia Central Railroad. Bridge at milepost 1.4 is a two span simply supported, through plate girder bridge. The span lengths are 97.042 feet and 95.583 feet. Bridge at milepost 5.8 is a single span simply supported open deck bridge with a span of 17.875 feet. These bridges are evaluated for the load ratings using AREMA 2014 manual using the allowable stress method. Since, the material properties of the bridge members are definitely unknown, the yield strength of steel assumed is in accordance with the instructions in AREMA 2014 manual. The two steel bridges referred to in this report were load rated using Cooper E 80, 286k railcar, GP 38, and GP 9 locomotives. WVU-CFC has performed the visual inspection in May 2014 on the bridges for general condition assessment and measuring section loss. The visual inspection revealed negligible section loss on the interior bottom angles, towards the north-west of girder two, just above the bearings. Hence, for the evaluation of load ratings, the reduction in dimensions are not taken into account. The bridge members including girders, floor beams, and stringers are analyzed for maximum bending moments and shears using RISA (Structural Analysis) software, in conjunction with MS-EXCEL calculations for load rating. The field-testing performed in August 2014, on these two bridges at mileposts 1.4 and 5.8, measuring deflections, strains including flexural compression, flexural tension and shear strains for girders, floor beams and stringers. During field-testing, WM 82 locomotive and hi-rail dump truck were used as live loads, moving at crawling speed, across both bridges. Field-testing results obtained for main girders of bridge 1.4 were in the range of 5% to 12% lower than the analytical results in the case of the hi-rail dump truck and 7% to 10% lower than the analytical results in the case of the locomotive. The floor-beam shear strains measured in the field are 50% to 88% lower than the analytical results. The difference between the floor beam shear strains may be due to the software limitations and assumptions while modeling the end conditions of floor beams. For stringers, field testing results for flexural strain were 63% lower than the analytical strains for the hi-rail dump truck load, 12% lower than the analytical result for the locomotive. For bridge 5.8, the field test results for flexural strains were 48% to 57% and shear strains 41% to 63% lower than analytical strain. Such discrepancy may be due to the contribution from the track structure not being accounted for in the analytical model. The scope of rehabilitation of the bridge embankments are also discussed in the report. There is no evidence of any settlements and disruption of embankments, however, gaps were observed between track and subgrade indicating draining out of ballast due to loosened surface material. Regular inspection for track and embankment stability were recommended at both the bridge sites. Further, building timber walls to prevent sliding of ballast is recommended to stabilize embankment and to prevent major maintenance issues. Based on field inspection, load rating analysis, and field testing, it has been found that bridges 1.4 and 5.8 can safely carry rolling stock equipment including, 286k railcar, GP 38, GP 9 and WM 82 locomotives, at 10 mph speed. Also, it has been concluded that the two steel bridges did not need any structural rehabilitation.

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