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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Determination of Lateral Resistance of Deck Tie Fasteners in Smooth Top Bridge Girders

Vasudevan, Vishali Mylapore 24 May 2018 (has links)
The purpose of this research was to investigate and create preliminary design aids for the determination of lateral resistance capacity and spacing requirements of deck tie fasteners in curved railroad bridges with smooth top girders. In railroad bridge design, required lateral resistance dictates the spacing of deck tie fasteners. Currently, no provisions exist to aid in the calculation of lateral resistance for systems that include bridge ties, fasteners, and girders which experience centrifugal or lateral forces. Thus, design practices specific to each railroad vary, producing inconsistent fastener spacing in existing railroad bridges. This project identified and quantified three factors contributing to lateral resistance through experimental testing: resistance due to friction at the tie-girder interface; resistance from the fastener; and resistance from dapped ties bearing against the girder flange. Three fastener types were studied in this research: Square body hook bolts, Lewis Forged hook bolts, and Quikset Anchors. Results indicated that frictional resistance is a product of the train wheel load and the friction coefficient. Fastener resistance was determined to be a function of fastener type and lateral track displacement. Finally, dap resistance was found to be a function of the area of the shear plane in a dapped tie. A preliminary equation for calculating the total lateral resistance capacity was developed utilizing superposition of all three resistance contributions. Lateral demand loads were compared with reported lateral capacity to create a preliminary design aid to determine fastener spacing. / Master of Science / Railroad bridges are constructed by securing wooden ties to I-shaped steel beams (girders) using deck tie fasteners. Curved railroad bridges should provide lateral resistance to resist lateral loads from trains negotiating the curve. Currently, there is no official practice for determining lateral strength, which is a function of fastener spacing. Thus, each railroad company uses a proprietary fastener spacing, producing inconsistencies in existing railroad bridges. The purpose of this research was to create a preliminary table or equation for determining the lateral strength and spacing requirements of deck tie fasteners through experimental testing. This project identified and quantified three factors contributing to lateral resistance: resistance due to friction at the tie-girder interface; resistance from the fastener; and resistance from dapped ties (ties that are notched to sit on the girder flanges). Three fastener types were studied. Results showed that frictional resistance was directly proportionate to the magnitude of the vertical wheel load. Fastener resistance was found to be a function of the type of fastener used. Finally, the dap was determined to be a function of the area of the shear plane in a dapped tie. A preliminary equation for calculating the total lateral resistance capacity was developed by summing the resistance contributions from all three resistance factors. Lateral loads were compared with lateral capacity to create a preliminary design aid to determine fastener spacing.

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