2015 CSCE Annual Conference Regina - Building on our Growth Opportunities

2015 CSCE Annual Conference Regina - Building on our Growth Opportunities Conference

Timber Beams Post-tensioned with Hardwire Sheets

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Dr. Dagmar Svecova (Presenter)
Dr. Hanan Al-Hayek, University of Manitoba

Ever increasing traffic demands and environmental exposure of timber bridges have reduced their performance over the years. The large number of these structures in many jurisdictions makes development of effective strengthening techniques essential for planning the maintenance of these structures.  An experimental program was undertaken at the University of Manitoba to determine the effect of post-tensioning of timber beams using hardwire sheets on performance of these beams. The emphasis of this work was primarily on the flexural behaviour and on the effect of this technique on the stiffness of the timber beams. A total of six salvaged Douglas-Fir creosote treated timber beams were tested in three point bending till failure. The dimensions of beams were 130 mm wide x 330 mm deep x 4500 mm long. The beams were reinforced with GFRP sheets at an angle of 45? in the shear zone to prevent shear failure. The beams were post-tensioned with hardwire sheet on the tension side. Four beams were post-tensioned with medium density hardwire sheets and the other two beams were post-tensioned with high density hardwire sheets. The dimensions of the hardwire sheets were 120 wide x 0.74 mm thick x 5000 mm long. The results showed small increase in the stiffness of the timber beams post-tensioned with medium and high density hardwire sheets on average by 3% and 6%, respectively. The increase in strength was more significant, on average 60%.