Durability and Ultimate Flexural Loading of Shear Spike Repaired, Large-Scale Timber Railroad Bridge Members
The objective of this research study is to examine the long term effectiveness and durability performance of fiber reinforced polymer (FRP) strengthened full size timber bridge members and to investigate their behavior when ultimately load tested. The shear spike strengthening approach is aimed at rejuvenating horizontal shear properties by inserting fiberglass pultruded rods through areas of damage. Shear spike fiberglass rods are inserted through predrilled holes from the top of the member, perpendicular to the primary bending axis. An epoxy-resin adhesive is incorporated during the process of insertion to bond the shear spikes to the wood. The epoxy adhesive also strengthens the member by filling adjacent cracks and decay voids. In three preceding investigations, this strengthening method has been proven to restore much of the virgin member stiffness and add horizontal shear resistance in dimension lumber, medium-sized timbers and full-sized bridge timbers, respectively. 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; FRP rods are highly effective in restoring the flexural stiffness and shear strength of deteriorated timber members.
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Supplemental Notes:
- This research was funded by the U.S. Department of Transportation, University Transportation Centers Program.
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Corporate Authors:
Colorado State University, Fort Collins
Department of Civil Engineering
Fort Collins, CO United States 80523-1372 North Dakota State University
Fargo, ND United States 58108 -
Authors:
- Gutkowski, R M
- Forsling, H
- Publication Date: 2007-12
Language
- English
Media Info
- Media Type: Digital/other
- Features: Figures; Photos; References; Tables;
- Pagination: 71p
Subject/Index Terms
- TRT Terms: Cracking; Deterioration; Durability; Fiber reinforced materials; Flexural strength; Polymers; Railroad bridges; Shear strength; Strength of materials; Structural deterioration and defects; Wood structures; Wooden bridges
- Subject Areas: Bridges and other structures; Railroads;
Filing Info
- Accession Number: 01090205
- Record Type: Publication
- Report/Paper Numbers: MPC Report No. 07-190
- Files: UTC, TRIS
- Created Date: Mar 21 2008 8:13AM