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Title:Durability and Ultimate Flexural Loading of Shear Spike Repaired, Large-Scale Timber Railroad Bridge Members
Authors:Richard Gutkowski and Henry Forsling
University:Colorado State University
Publication Date:Dec 2007
Report #:MPC-07-190
Project #:MPC-261
TRID #:01090205
Keywords:cracking, deterioration, durability, fiber reinforced materials, flexural strength, polymers, railroad bridges, shear strength, strength of materials, structural deterioration and defects, wooden bridges, wood structures
Type:Research Report – MPC Publications


For this study, eight full-size railroad bridge timber stringers were intentionally damaged by saw cuts, to mimic deterioration, after which they were strengthened through the process of shear spiking. The stringers were then durability loaded up to 25,000 cycles after which the majority of the sample population was ultimately load tested. The strengthened stringers showed very modest detrimental effects from the repetitive nature of the loading. In subsequent ultimate load testing of the repaired beams, specimens failed predominately in flexure, i.e. failure in the sound wood rather than in the strengthening components. The results found support findings from those previous studies; fiber reinforced polymer (FRP) rods are highly effective in restoring the flexural stiffness and shear strength of deteriorated timber members.

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