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June 19, 2012 - Corrosion of steel reinforcement due to environmental effects is a major cause of deterioration problems in bridge barriers. Glass fibre reinforcement not only addresses this durability problem, it also provides exceptionally high tensile strength and Young’s modulus. The special ribbed surface profile of the studied glass fibre bars and end anchorage heads ensures an optimum bond between the concrete and the bar, and thus eliminates the need for custom-made bent bars. A recent design project conducted at Ryerson University on a PL-3 bridge barrier proposed the use of 16 mm and 12 mm diameter glass fibre bars as vertical reinforcements in the barrier front and back faces respectively, with 16 mm diameter bars as horizontal reinforcements in the barrier wall, all at a spacing of 300 mm. The connection between the deck slab and the barrier wall utilized the glass fibre headed end bars for proper anchorage.
Fibre reinforced polymers (FRPs), as non-corrodible materials, are considered an excellent alternative to reinforcing steel bars in bridge decks and other elements such as barriers, sidewalks and wingwalls to overcome steel corrosion-related problems. Since they are less expensive than carbon and aramid FRPs, glass fibre reinforcing bars are more attractive for bridge deck and barrier applications. Until recently, the installation of glass fibre bars was often hampered by the fact that bent bars have to be produced in the factory because FRP bars cannot be bent at the site. Also, bent FRP bars are much weaker than straight bars.
The test wall was designed according to the Canadian Highway Bridge Design Code. The design was based on the results of material tests on headed glass fibre reinforcing bars and on the results of two full-scale tests on 1,200 mm long PL-3 wall segments performed at Ryerson University in 2010. The final design called for 16 mm and 12 mm diameter GFRP bars as vertical reinforcements in the barrier front and back faces respectively, with 16 mm diameter bars as horizontal reinforcements, all at a spacing of 300 mm. The connection between the deck slab and the barrier wall utilized the GFRP headed end bars for proper anchorage.
In November 2010, a vehicle crash test was conducted in accordance with Test Level 5 (TL-5) of MASH, which involves the 36,000V van-type tractor trailer (cab-behind-engine model of 36,000 kg gross weight) impacting the barrier at a nominal speed of 80 km/h and an angle of 15 degrees.
The remote controlled tractor trailer impacted the barrier at 620 mm upstream of the control joint located at 10.8 m from the barrier downstream end. As the test vehicle continued driving along the barrier, it righted itself and rode off the end of the barrier wall. The brakes on the test vehicle were not applied, and the test vehicle subsequently came to rest 35.66 m downstream of the end of the barrier and 2.7 m towards the field side.
The test showed that the barrier withstood and redirected the vehicle. It did not penetrate, underride or override the parapet. No elements, fragments, or other debris became detached from the barrier that could potentially penetrate the cab, or cause undue hazard to others in the area. No deformation occurred to the cab. The 36,000V test vehicle remained upright during and after the collision. After the crash test, minor cracks in the front and back faces of the barrier were observed, but there was no severe damage.
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