Prefabricated Bridge Elements and Systems
Powerpoint VersionSlide 1. FRP Industry Efforts and Capabilities to Support PBES Deployment
| John P. Busel Director, Composites Growth Initiative American Composites Manufacturers Association (ACMA) | Dan Richards, Ph.D, PE
President & CEO – ZellComp, Inc. Chair, ACMA Transportation Structures Council |
Speaker Notes:
Welcome. This is Module 9 that will cover the FRP Industry Efforts and capabilities to support PBES deployment.
Slide 2. Learning Outcomes
- Composites Materials
- Specifications and Standards
- FRP Products for Infrastructure
- Summary
Speaker Notes:
The outline for the presentation will cover a basic overview of composites materials. This will be followed by a review of current specifications and standards that engineers, designers and specifiers could use to specify various composites products. Next we will review various deck and girder and other infrastructure products that have been tested and deployed in the field by looking at several case histories. The presentation will be concluded with how composites supports FHWA’s program of Every Day Counts.
Slide 3. Composites Materials
Speaker Notes:
Lets start with a review of the materials.
Slide 4. What are Composites?
- Composites Material – Engineered materials which consist of more than one material type.
- For this discussion, Composites Material is – Any combination of polymer matrix and fibrous reinforcement
Speaker Notes:
Composites are engineered materials. There are many forms of composites materials. Composites could be applied to the human bone structure. The first form of composites existed with the ancient Egyptians when they combined mud and straw to form bricks used in construction. Today’s composites materials are found in many applications from automobiles, trucks, airplanes, recreational equipment, industrial equipment, and finally transportation infrastructure which is the focus of this presentation.
For this discussion, composites materials is simply the combination of a polymer resin matrix and a fiborous reinforcement.
Slide 5. Fiber Reinforced Polymer (FRP)
FRPs are composites materials:
- materials created by the combination of two or more materials, to form a new and useful material with enhanced properties that are superior to those of the individual constituents alone
Speaker Notes:
Composites are also referred to FRP, meaning Fiber Reinforced Polymers. Composites mean FRP and vice-versa.
Basically, the definition of FRP or composites is the combination of two or more materials, that when combined, form a new materials with superior properties compared to the individual components.
Slide 6. Thinking Composites
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Speaker Notes:
We need to ask ourselves – Why build with the same old materials? In this day and age of tight budgets and the increasing need to rehabilitate our infrastructure, can we afford to repeat the cycle when we need to install durable, longer lasting structures?
We need to think composites. The inherent properties of composites often translate to efficiently built structures. For example, composites are light weight and can be easily transported and installed because they are easier to handle.
Composites are high strength 5 times that of steels properties. Composites are highly versatile meaning that the designs and performance can be tailored to suit just about any project. Composites are naturally corrosion resistant in that they are non-metallic this results in more durable structures when exposed to harsh environments.
But composites do not stop there. There are many more attributes whereby composites maintain greater value.
In addition to high strength, light weight, and corrosion resistance, composites can be engineered to: have superior electrical properties, especially glass fiber where it functions as an insulator high thermal properties as composites do not transfer heat and cold and can perform in many environments non-magnetic – composites are non-metallic and therefore perform excellent in ths environment composites are transparent to radar signals Ultimately, composites are durable materials that when designed and manufactured properly offer a long service life even exposed to the harshest environments.
Slide 7. Composites Features
- Composites designs embodying the following attributes will provide superior value to traditional materials.
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Slide 8. FRP Materials
What is FRP? Fibers
|  | Constituents Matrix
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Fiber Composite Matrix |
Creates a material with attributes superior to either component alone! fibers and matrix both play critical roles in the composites material...
Speaker Notes:
Composites are made with several components starting with man-made fibers such as glass, carbon or aramid. These fibers provide the strength and stiffness in a composite. The fibers are then combined with a polymer resin like polyester or epoxy. The resin protects the fibers from environmental attack and helps transfer the loads between the fibers.
The combination of the FIBER and the RESIN creates a material with attributes superior to either component alone and is critical in the performance of the composites material. Composites exhibit strength that is 5 TIMES stronger than steel at ¼ the weight, and offering corrosion resistance, and many other benefits.
During this presentation, composites will be referred to as FRP – meaning fiber reinforced polymer, or "fiberglass" This is an industry term not only applied to the fiber component, but a description associated with a non-metallic material. You might be familiar with "fiberglass boats".
Looking at a stress-strain curve, the individual components of the fiber and the resin retain their individual properties, but when combined, the composites materials have superior properties.
When compared with steel, a FRP composite performs with a linear strain to failure. Although composites have a higher stress threshold than steel, one must design differently than for steel to account for the lack of ductility. This can be done.
Slide 9. Specifications & Standards
Speaker Notes:
We will now focus on currently available design standards and specifications for composites.
Slide 10. Specifications & Standards, (Cont’d.)
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Speaker Notes:
One noteworthy design standard published by AASHTO in 2009 is the AASHTO LRFD Bridge Design Guide Specifications for GFRP Reinforced Concrete Bridge Decks and Traffic Railings. Using the ACI design guide as a foundation, this publication will assist bridge engineers in specifying FRP rebar in concrete bridge decks.
This was the second of two AASHTO publications to cover FRP.
Slide 11. Specifications & Standards, (Cont’d.)
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Speaker Notes:
First published in 1999, the ACI 440.1R-06 evolved from emerging technology to ACI standard publications on the use of FRP bars to reinforce concrete. This publication has gone through 3 iterations over the years to refine the design equations used in this document. This has become a well reference and used world-wide design document as the authority for internally reinforced concrete with FRP bars.
Slide 12. Specifications & Standards, (Cont’d.)
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Speaker Notes:
In Canada, FRP bars used in the design of concrete bridge decks have been codified in the Highway Bridge Design Code. The existence of this document has motivated all Canadian provinces to specify and install FRP rebar as a material of choice for concrete exposed to aggressive environments.
Slide 13. Specifications & Standards, (Cont’d.)
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Speaker Notes:
As a compliment to the ACI 440.1R design specification, this ACI standard was developed for contractors and specifiers who use either glass or carbon FRP bars as a materials specification to be used in contract documents. It is written in mandatory language and contains provisions governing testing, evaluation, and certification of FRP bars used in reinforced concrete.
Attention was placed on minimum requirements the FRP bars must meet to ensure durable performance.
Slide 14. Specifications & Standards, (Cont’d.)
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Speaker Notes:
This ACI standard also serves as a compliment to the ACI 440.1R design specification. This construction standard provides information for contract documents that guide contractors and engineers on the proper use and installation of FRP bars for reinforced concrete.
Slide 15. LRFD – Pultruded Composites
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Speaker Notes:
ASCE, under contract with the American Composites Manufacturers Association completed a 3-year project to develop a new design pre-standard titled LRFD of Pultruded Fiber Reinforced Polymer (FRP) Structures. This pre-standard was published in late 2010 and is currently going through the ASCE standards process to promulgate this document as a standard.
The publication covers a number of areas of pultruded composites including tension members, compression members, flexural and shear members, combined forces and torsion, plates and built up members, and bolted connections. Each of the chapters follows the LRFD design provisions laid out in chapters 1 and 2.
The LRFD document can be applied to all pultruded structural elements.
Slide 16. FRP Products for Infrastructure
Speaker Notes:
Now, lets focus on the products and field installations.
Slide 17. Pultrusion Process
Speaker Notes:
First, we need to understand a composites manufacturing process called pultrusion. Most products used for transportation infrastructure applications including rebar, structural profiles, girders, decks, and strengthening materials use pultrusion to manufacture the product.
The process starts as long continuous fibers called rovings (either glass or carbon fiber) are pulled through a resin bath to saturate the fibers, then the wet fibers are aligned and pulled through a shaped mold die which is heated. While the composites are in the die, the shape is formed and fully cured. The completed profile exits the die and is cut to length based on the requirements for the order
Slide 18. Pultrusion Manufacturing
Consistent Quality
Speaker Notes:
This is a picture of a pultruded part exiting the heated die. This part is used as the lower part of a bridge deck. Depending on the width of the bridge, the part is cut to final shape. The part is fully cured and retains its shape.
Slide 19. FRP Deck for Highways
Applications
| Past | Tyler Road Bridge | Present |
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Speaker Notes
Pultruded FRP decks are not new. First developed in the mid 1990’s, pultruded FRP decks have been extensively tested in the laboratory and the field. Primarily deployed to rehabilitate existing bridges, FRP decks can transform a deteriorated structure into a beautiful and durable structure. There are various pultruded bridge deck configurations that range from a 1-piece full section depth to multi-piece configurations. FRP decks are factory built and assembled, transported to the field either as the entire bridge or in a few components to minimize field joints and speed the installation time.
Slide 20. Case Study
Applications
Speaker Notes
Lets take a look at a case study in Portland Oregon.
Slide 21. Broadway Bridge
Applications
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Speaker Notes:
The Broadway Bridge is an aging historic bascule bridge that is located in the center of Portland. It is a well traveled bridge with 30,000 ADT and services vehicular and pedestrian traffic, and is also a major component for marine traffic with ships and barges. This significant structure, if out of service for an extended period of time will have a huge impact to all forms of traffic in Portland.
The problem with this bridge was that the open steel grating for the road bed was severely deteriorated and needed to be replaced. There was a desire by the DOT to improve the skid resistance on the deck. In addition, it was desired to lighten the deck to minimize rework on the motors to control the bascule portion of the bridge.
Slide 22. Installation Place Full Section Panels
Applications
Speaker Notes:
The solution was to install a light weight FRP deck which provided a solid surface to provide better skid resistance. The FRP deck was assembled into panels at the factory and delivered to the site. Light duty crane trucks were used to place the panels into place on the bridge. Each panel was sized to go the full width of the bridge to minimize any seams and joints.
Slide 23. Results
Applications
One of largest & most traveled FRP decks |
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 Completed miscellaneous tasks on 3rd shift Ready for bascule opening on 4th day |
Speaker Notes:
The construction was carefully planned not to disrupt the marine traffic. Over 12,000 sq ft of FRP bridge deck was installed on this bridge in 2 shifts. By the 3rd shift, all miscellaneous tasks were completed making the bridge ready by the 4th day to allow marine traffic to move down the river.
The pre-engineered, pre-fabricated bridge decks allowed for minimal disruption of traffic. In this case, Every Day did Count.
Slide 24. 2-piece Deck Design
Prefabricated & Pre-Engineered
= Low-cost & Easy to Assemble
(5 Inch Deck ~ 16 Lbs/ft.^2;7 inch Deck ~ 18 Lbs/ft^2 )
Speaker Notes:
The next case study deals with the replacement of an old corroded open steel deck in Florida. For this project a two part FRP deck system was selected. This system utilizes mechanical fasteners, which are locked with epoxy to prevent any backing out. This deck is an "open" design, which offers flexibility on site and the ability to repair and reassemble if ever needed. The pultruded bottom section (the base plate with T sections) provides the majority of the structural capacity. The bottom section can be manufactured in different depths, depending on the spacing of the stringers for the particular project. This open deck system allows for easy connections to the superstructure and can be used with either shear studs and grout or with bolts.
Slide 25. Florida Lift Bridge: 19,000 ADT, 28 Degree Skew – Bottom Sections
Speaker Notes:
FRP decks are an excellent choice for moveable bridges due to their light weight and corrosion resistance characteristics. This particular deck design was tested by the Florida Department of Transportation and the University of Central Florida in advance of this installation. This bridge in Florida was a 6-lane lift bridge over a canal. This slide shows the bottom sections that were installed. There was a skew of 28 degrees that would normally require extra reinforcement, but this design was cut to the skew and eliminated the need for additional and costly structural steel reinforcement.
Slide 26. Shear Studs Installed at 16" Spacing with Grout
Speaker Notes:
Connections are easy and fast with this two-part deck. This slide shows the shear studs with foam dams that create a grout pocket around the shear stud. There is easy access for installing the grout around the shear stud pockets.
Slide 27. Fastening Down the Top Sheets
Speaker Notes:
The next step is the installation of the top sheets. For this project, the top sheets were cut on site to exactly fit the skewed structure. Adjustments often need to be made, and this deck offers that type of flexibility onsite.
The top sheet is attached with mechanical fasteners. The fastener heads can be set at different depths depending on the wear surface material to be used. Customers typically select a polymer concrete wear surface with an FRP deck, but asphalt can also be used if preferred by the customer.
Slide 28. FRP Bridge Superstructure
- Integrally molded superstructure (deck and beams)
- Minimizes field joints
- Fast installation
- Eight Mile Bridge, Hamilton County, Ohio, April 2008
- Span = 22 feet; Width = 62 feet – 1364 sq. ft.
- HS 20 loading (72,000 lb truck); Alt. Military Truck loadings
- L/800 deflection criteria (deflection is less than 0.31 inch)
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Speaker Notes:
The next case study covers the installation of an FRP bridge superstructure (deck and beams) in Ohio. This deck is manufactured via the resin infusion process.
Slide 29. FRP Superstructure Applications
- Focus on light weight and fast installation
- Permanent Vehicle Bridges
- For Fast Installation
- Temporary Vehicle Bridges
- Bypass adjacent to permanent bridge
- Same load and deflection requirements
- Rural areas with long detour options
- Temporary Equipment Bridges
- Work Trestle
- Cranes, support vehicles and personnel
Speaker Notes:
This design can be used in a variety of bridge types.
Slide 30. Original Bridge Site
Speaker Notes:
This picture of the original bridge site shows the harsh environment that the materials are subjected to. Fast and easy installation were important to the customer.
Slide 31. Original Bridge Site, (Cont’d.)
Speaker Notes:
The deck/beam modules were easy to drop into place with a crane. Prefabricated composite bridge components clearly eliminate days from a construction schedule. This close-up of the sections being dropped in shows that the design eliminates joints. The abutments were constructed to allow for easy connection.
Slide 32. Original Bridge Site, (Cont’d.)
Speaker Notes:
The main structure was completed in one day certainly meeting the goal of Every Day Counts.
Slide 33. Original Bridge Site, (Cont’d.)
Applications
Speaker Notes:
This is the final installation. Now a very clean looking bridge. In addition to working with accelerated construction, composite materials offer a very long life cycle compared to traditional construction materials.
Slide 34. FRP Rebar for Decks & Approach Slabs
Speaker Notes:
Since the early 1990’s, FRP rebars have been used in a variety of bridge deck applications. There are in excess of over 200 installations in North America that use FRP rebar today. Several of those installations are shown in these pictures. In every case, FRP rebar is either used in the top mat, or top/bottom mat of the deck. FRP rebars corrosion resistance provides engineers with alternative materials for structures in aggressive environments.
Slide 35. Prefabricated FRP stay-in-place reinforcement panels
Large-size 24’ x 8’, double-layer stay-in-place (SIP) reinforcing panels pre-assembled using off-the-shelf pultruded GFRP components
Speaker Notes:
A technology developed over 8 years ago introduced another approach to reinforced concrete decks that incorporate a structural stay-in-place formwork coupled with a 3 dimensional grid reinforcement. The reinforcement is made from existing pultruded grating bars that are joined together to form a grid. These grids can be formed into panels, much like prefabricated FRP decks, and installed on a bridge.
Prefabricated stay-in-place FRP reinforcing panels take advantage of advanced composites’ versatility, light weight, and corrosion resistance, to make the construction of durable bridge decks faster, safer, and competitive.
Slide 36. Grid Panels Stacked and Shipped to Bridge Site
Speaker Notes:
The grid panels can be stacked and shipped on trailers very efficiently.
I-bars (38 mm) running continuously in the direction perpendicular to traffic;
Three-part cross rods running through pre-drilled holes spaced at 100 mm on-center in the I-bars web in the direction parallel to traffic; and
Two-part vertical connectors that space the grating layers 100 mm apart.
Slide 37. Old Bridge 14802301 Greene County, MO
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 * Source: Great River Engineering of Springfield (2004) |
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Speaker Notes:
Lets take a look at a case history. This bridge in Greene County, MO was long overdue to be refurbished. The bridge was posted and was in various state of disrepair.
Slide 38. Deck construction
- Day 1: SIP panels setting and anchoring
Speaker Notes:
The construction process was performed in a simple 5-day sequence of events. Day 1 was assigned to setting the panels in place. Note that a light duty truck crane was used to place the panels.
Slide 39. Deck construction (Cont’d.)
- Day 2: installation of post cages...
Speaker Notes:
During Day 2, the traffic railings were built up with standard FRP rebar and tied to the prefabricated stay-in-place grid forms. Details such as drains, drip edges and expansion joints were built in.
Slide 40. Deck construction (Cont’d.)
Day 3: deck casting...
...and finishing
Speaker Notes:
By Day 3, the bridge deck was ready for casting of the concrete. The surface was safe for workers to walk on and perform the casting process.
Slide 41. Deck construction (Cont’d.)
Day 4-5: rail beam cages mounting...
...and casting
Speaker Notes:
Day 4/5 were assigned to finish the railings and other details on the bridge.
Slide 42. Deck construction (Cont’d.)
Speaker Notes:
This composite picture shows various views of the completed structure.
Easier and faster construction – the elimination of labor-intensive and time-consuming field operations (formwork setting between the girders, and tying of rebars) by means of large-size prefabricated FRPpanels lifted with a single pick of a crane, translates into over 70 percent reduction in construction time from reinforcement installation to deck casting and finishing, as well as into significantly improved working conditions.
Higher Productivity – the rate of concrete placement is increased by 50 percent compared to traditional steel reinforced decks with similar dimensions.
Reduced Labor Cost – the reduced need of manpower, faster and easier field operations, and higher productivity translate into over 75 percent reduction in deck construction labor cost.
Improved safety – the use of very lightweight FRP panels, easy to handle and placed with no need of formwork (as opposed to heavy partial-depth precast prestressed panels commonly used), and the design of the reinforcing profiles to facilitate walking over the top mat, result in improved safety in the work area.
Enhanced durability – to date, the results of extensive research have demonstrated the superior durability of internal FRP reinforcement for concrete when compared to steel rebars. The corrosion resistance of FRP composites represents a critical advantage for bridge decks, which are highly susceptible to deterioration due to chloride (deicing salts) penetration. This translates into a reduction in bridge maintenance operations, thereby supporting a more efficient bridge management, and prioritization of limited funds.
Slide 43. FRP Tendons: Bridge Girders
Speaker Notes:
In the early 1990’s researchers in Canada first applied CFRP tendons for prestressed concrete beams. This multi-span bridge in Manitoba Canada performs beautifully today. The girders have internal sensors that are used to monitor the service of the girder and bridge system.
Slide 44. Repair and Rehabilitation
Applications
Externally-bonded carbon FRP sheets for shear strengthening of a reinforced concrete bridge girder
Speaker Notes:
Rehabilitation is another tool for engineers to get structures in service and extend the service life of installations. The use of FRP composites for external strengthening of concrete structures is well documented and used in thousands of installations. The upgrades can be tailored to enhance shear, flexure, of girders or decks.
Slide 45. Repair and Rehabilitation
Externally-bonded carbon FRP sheet for axial strengthening (confinement) of a reinforced concrete column.
Speaker Notes:
Enhancing the durability of bridge columns has been widely used with both glass and carbon fiber FRP systems. This is a picture of a technician applying CFRP to a column.
Slide 46. Hybrid Composite Beam
Applications
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Speaker Notes:
In development for over 10 years is this Hybrid Composite Beam. It is a highly efficient concrete beam that includes a tied-arch in a fiberglass box. This design provides a cost effective solution that uses the best of FRP composites, steel, and concrete which provides for a stronger, lighter and more corrosion resistant alternative to current precast girders. This girder has been extensively tested and approved to be used for railroad bridges.
Slide 47. Next Stop, New Jersey
Route 23 Bridge over Peckman’s Brook
Speaker Notes:
The HCB girder has been installed on a number of bridges in Illinois, New Jersey, and Maine. The girders light weight allows many girders to be transported in a single shipment. This reduces the number of trucks needed to transport the girders, reduces the energy needed to drive the trucks, reduces the number of trucks on site in a staging area. The reduction of the staging area reduces congestion and increases safety.
Slide 48. Erected with Track Hoe
Applications
Speaker Notes:
While on site, typical construction equipment can be used to lift and place the girders on the site reducing a contractors cost of renting special lift cranes and other equipment. Again, the light weight beam allows for quick installation, often completing the placement in a matter of hours. The quick installation translates to less traffic congestion while increasing safety on site.
Slide 49. High Road Bridge Complete
Speaker Notes:
When completed, the HCB girder looks like any other bridge girder that provide pleasing aesthetics to the overall structure. Currently, a large multi-span bridge is being constructed in Maine using this girder system.
Slide 50. Bridge in a Backpack
| Arch Placement | Decking Installation | Completed Bridge |
Speaker Notes:
The Bridge in a Backpack system was developed at the University of Maine’s AEWC Advanced Structures & Composites Center over an 8 year period. Through a combination of research funding from the Maine DOT, the US Army, and several other sources total research funding to date is approximately $4 million. The system is currently being commercialized by Orono, ME Advanced Infrastructure Technologies, a five person team of engineers and investors.
The system is comprised of an external shell made from CRFP fabric assembled into a sock in which concrete is pumped into the arch girder. The process is done on site. The complete arch is then lifted into place using light duty crane equipment. A corregated decking is then placed on top of the girders and backfill soil placed to complete the structure.
Slide 51. Completed Neal Bridge
Speaker Notes:
The entire process can be done within a week for most structures. The FRP materials used provide a structure with a service life of 100+ years. Currently, 7 installations are planned for the State of Maine, along with many more in other locations around the world. The use of composites naturally preserves the environment around these short span bridges.
Slide 52. Module Conclusions
- Engineered systems
- Prefabricated components, factory built, quality controlled
- Reduces the need for large, heavy, expensive equipment during installation
- Easier handling Increases safety on site
- Light Weight Reduces Shipping, Handling and Erection Time and Costs (Accelerated Bridge Construction)
- LowerCarbon Footprint
- Greater Corrosion Resistance than Conventional Materials Providing Service Lives Beyond 100 Years
- LOWER OVERALL BRIDGE COST!!
Speaker Notes:
In summary FRP composites are:
- Engineered systems
- Prefabricated components, factory built, quality controlled
- Reduces the need for large, heavy, expensive equipment during installation
- Increases safety on site
- Lighter Weight for Reduced Shipping, Handling and Erection Time and Costs (Accelerated Bridge Construction)
- Reduced Carbon Footprint
- Greater Corrosion Resistance than Conventional Materials Providing Service Lives Beyond 100 Years
- LOWER OVERALL BRIDGE COST!!
Slide 53. Module Conclusions, (Cont’d.)
- Every Day Counts – Composites
- Inspire innovation with different designs using similar materials
- Encourage ingenuity because it allows you to think outside the box
- Facilitates invention by making existing techniques, systems, methods better
- Propels imagination into new frontiers to make an engineers or contractors vision a reality
Speaker Notes:
The goals of Every Day Counts are supported by composites where innovation, ingenuity, invention, and imagination are the cornerstones of FRP materials.
Slide 54. Module Conclusions, (Cont’d.)
Lightweight Material
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Prefabricated Structural FRP Designs
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Quick Installations that will last longer than a Life Time
Speaker Notes:
So what do you call a material that is lightweight, can be made into prefabricated structures and translate to quick installations that will last longer than a life time – we call them FRP composites.
Slide 55. Questions?
John P. Busel |
Dan Richards |
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