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

Abstract

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.