Presentation on theme: "“Advanced technology for bridge superstructures”"— Presentation transcript:
1 “Advanced technology for bridge superstructures” GFRP (Glass-Fiber-Reinforced-Polymer) Composite System for Bridge Superstructures“Advanced technology for bridge superstructures”Cantat Associates Inc.Toronto, Ontario, Canada2010
2 1. How did it happen?As it is known, the actual lifespan for steel, reinforced concrete and steel-reinforced concrete SS’s everywhere in the world is no longer than 35 to 50 years, which is much shorter than Canadian, American, or European Bridge Design Code requirements. The causes for such a dramatic mismatch, in our analysis, are:1. Acid rains, occurring with increasing frequency over the last several decades.2. De-icing salts widely used to prevent traffic sliding.3. Contaminating debris, increasingly being brought on deck wearing surface by truck wheels.4. Damage to structural elements due to fatigue.The cause for such a short lifespan cannot be blamed on the growing weight of heavy trucks. In our opinion during the last 60 years, the average weight of heavy trucks has increased by no more than 20%. Within the Bridge Design Codes, this problem is solved by using conditional live loads (i.e. conditional heavy trucks, much heavier than real trucks) and a significant magnitude of live load factor in calculations, as well as much better than theoretical live load redistribution in real superstructures. The precise space calculations of a superstructure’s cross-sections and test results are confirming this statement theoretically as well as practically.To summarize: the unanticipated changes in environment and material properties over time are the primary causes for dramatic reduction in the service life of bridges. The secondary cause in the SS’s degradation is insufficient funding for proper maintenance.
3 2. What to do?The obvious conclusion for the Engineers was to seek alternatives to the materials conventionally used in bridge construction and rehabilitation. The solution would involve using materials that are not vulnerable to environmental damage and would increase service life, which means durability of bridge SS’s. On the other hand, the life cycle and maintenance costs would have to be competitive with traditional materials, because of the limited resources available for maintaining those bridges. Such alternative material was found. It is FRP (Fiber-Reinforced-Polymer)-composite product.In the mid 1930s as a part of experiment FRP was used for a boat hulls. From that point on and during the following 50 years, FRP-composite was used in marine, chemical processing, aerospace, for military items and transportation. Now, the worldwide attention is focusing on the opportunities offered by structural composites and structural industry.Composite FRP material is formed by using high strength artificial fibers (for example E-Glass, Carbon-Fibers, Basalt-Fibers and so on) and Resin (vinyl-ester, polyester and Epoxy) and offers many advantages:It is very strong and durable material, not sensitive to environment;It is much lighter than concrete or steel.
4 According to Canadian official information, reinforced concrete and steel- reinforced concrete structures during their lifetime of 35 to 45 years required an additional investment for their maintenance and rehabilitation of at least % of their initial construction costs. FRP-composite structures on the other hand do not require maintenance, or require minimal investment for painting of their open surfaces.There are three main methods for production of composite structures:Molding (mostly for small structural elements);Pultrusion (mostly for extensive elements, relatively with conditionally small cross-sections);Infusion (mostly for big structural elements).Cantat Associates Inc. selected GFRP composite material using infusion method for production, high strength E-Glass Fiber and Epoxy Resin.
5 3. How did we solve it?GFRP-composite system for bridge superstructuresTo meet time and situation challenges, Cantat Associates Inc. have developed a composite system for bridge SS’s in which steel, wood and GFRP are working together. Steel and wood are totally encapsulated by GFRP casing and are protected against corrosion and degradation.In our R&D we tested thousands GFRP samples based mostly on American Standards ASTM:
6 Average Statistical test result Taken in consideration for design- Tensile strength and1,000 MPa800 MPacorresponding Modulus of Elasticity45,000 MPa35,000 MPa- Compression strength and900 MPa700 MPa42,000 MPa- Flexural strength andModulus of Elasticity46,000 MPa- Shear strength50 MPa20 MPaShear Modulus3,600 MPa2,400 MPa- Coefficient of linear Expansion/ °C/°C- Acceptable max value of the strain in GFRP (ULS – see § , CHBDS)-0.005 < [0.006]- Strains changes in GFRP equal strain changes in adjacent wood or steel (SLS – see § )- Durability test (UV-test with changing “t” from 130°C to -130°C) cycles – lost 1 micron~ 150 year- Mass density2,050 kg/m3
7 Glue-nailed Laminated timber core shell conform to CAN/CSA (Spruce-Pine-Fir selected wood or #1)Plywood shall be CANPly Exterior Canadian Softwood Plywood (CSP) certified by CSA-0151 (thickness shall not be less than 25.5 mm, number of plies shall not be more than 9, not less than 7)From year 2002 up until today we made a long way to get considerably adjusted GFRP material:To find the most efficient sections of our Hybrid GFRP composite structures;To efficiently include GFRP composite deck in combine operation with steel girders;To elaborate efficient details for deck fixation, to steel girders, barriers, the deck fixation to the steel frame;To attach elements of the deck to each otherWe already tested in full size GFRP-wooden composite beams 3m in length. We designed, tested and installed nine different superstructures from 11m simple span up to 90m one span, including a Hybrid – GFRP- composite deck and a Skew bridge. All those bridges had been designed and successfully used for the last 4-7 years under Truck Live Load 625 kN, one of those bridges is a pedestrian bridge over HWY 10, with continuous SS’s (scheme m). Another bridge was installed under a highway in Nova Scotia.
8 The main advantages of our GFRP-composite SS’s are: 1. Extremely long expected durability: over 100 years2. Light weight: increases superstructure's capacity or reduces volume of the material(s) (e.g. steel)3. Quick installation: usually installed and opened to public traffic in 2-3 hours4. Environment-friendly: prefabricated, eliminating scaffolding and contaminating debris5. Maintenance free life cycle: not sensitive to the environment does not corrode or deteriorate and only requires painting of deck (superstructure) open surfaces once in a decade6. Year-round construction: suitable for construction in both cold- and warm-weather conditions7. Final costs now is approximately 5-10% lower than steel or reinforced- concrete SS’s and no costs or minimal costs for their maintenanceThe primary reason for using GFRP-composite SS’s is their unique long-term durability. There are no alternatives to this product anywhere in the world.The Ministries of Transportation of both Ontario and Nova Scotia have already recognized and adopted this system.
10 Tests conducted Type of tests conducted coupons Beam sections, Deck sections,Results: MOE, Shear, etc.Testing conducted byCantat Associates Inc.University of Western OntarioTriodemIntegrity Testing LabResultsProduct in conformance
11 Page 194 of CHBDC says, the use of model analysis, involving the testing of a physical model of the whole or part of the bridge, is acceptable as an alternative to, or in addition to, other methods of analysis permitted in this Section.CHBDC CL 625 Truck Loading