In 2017, the City of London, Ontario launched a $7.9 million project to remove, dismantle and rehabilitate Blackfriars Bridge. The 143-year-old wrought iron bowstring arch-truss structure, which connects Ridout and Blackfriars streets, is Ontario’s oldest working crossing. The 221.5-foot long bridge deck carries vehicles, cyclists and foot traffic across the north branch of the Thames River. Concrete combined with current traffic loads proved too heavy for the historic structure. London-based Dillon Consulting and the City of London selected Composite Advantage’s fiber reinforced polymer (FRP) FiberSPAN deck following research and study of the product’s performance on two Ottawa vehicle bridges.
Design requirements included a design vehicle loading of 75% of CL3-625-ONT with a 1.3 dynamic load allowance and a 0.9 environmental durability factor. Allowable stress design (ASD) standards and limit states design (LSD) determined safety factors which were compared to design strain requirements. Traditional beam bending equations were used to analyze FiberSPAN deck panels constructed as a series of closely spaced I-beams. Panels met an L/500 deflection. Bending strain/shear strain was less than 20% under the service load plus dead load. Minimum fatigue life was rated at 2,000,000 cycles. Panels were designed to a temperature differential of 60 degrees Celsius. The design allows the bridge deck to move independently of steel beams in the longitudinal direction.
The FRP deck was installed on Blackfriars’ rehabilitated steel truss. Direct bolting of the 17.5 foot-wide panels was designed to handle braking loads while connection clips resist uplift and lateral movement of the bridge. Panel widths ranged from 7 inches to 9 inches thick with a molded in crown. Curbs, integrally molded into the FRP deck, were covered with 304, 3/8-inch thick stainless steel plates to protect from wheel impacts and snow plows. The FRP deck was given a dark aluminum oxide wear surface.
“Blackfriars Bridge is a key corridor into our downtown and a link to our local cycling network,” says Doug MacRae, Director of Roads and Transportation for the City of London. “We selected FRP decking for the Blackfriars Bridge rehabilitation project for its durability and corrosion-resistant qualities. We wanted a material that would reduce the amount of maintenance work needed once the bridge was reopened to pedestrians, cyclists and motorists.”
Composite Advantage supplies innovative fiber reinforced polymer (FRP) products for major infrastructure markets. To create its engineered solutions, the company pairs progressive designs with its capability to mold large parts, perform on-site assembly, and support customer installations. The supplier has been developing lightweight, high-strength, cost-effective FRP goods for structurally demanding applications and corrosive environments since 2005. Many of these products have paved the way for first-time use of FRP composites in infrastructure, rail and water applications because of their performance attributes. Composite Advantage's comprehensive lineup includes bridge decks, trail bridges, cantilever sidewalks and rail platforms to fender protection systems, pilings, naval ship separators and other waterfront structures.