Three futuristic composite bridge technologies - Bridge in a Backpack, Hybrid-Composite Beam, and ProCoBeam - are described that result in fast-track construction and more sustainable bridges with expected lifespans over 100 years. The Bridge in a Backpack uses fiber reinforced polymer tubes filled with self-consolidating concrete as main load-bearing elements. The Hybrid-Composite Beam has a fiber reinforced polymer shell housing a self-consolidating concrete arch tied by galvanized prestressing strands. ProCoBeam uses a shear composite dowel to connect a bottom steel T-section to a top concrete T-section.

1. The Bridge and Structural Engineer Volume 46 Number 2 June 2016 1
SUMMARY
Three futuristic composite bridges, viz., Bridge in
a backpack [using FRP tubes filled with SCC (Self
Consolidating Concrete) as the main load bearing
elements], Hybrid-Composite Beam (with a FRP
shell housing an arch of SCC which is tied at its ends
by high strength galvanized pre-stressing strand)
and ProCoBeam [with a shear composite dowel
connecting bottom steel T- section (with a specially
profiled web) with the top concrete T-section] are
described, which result in accelerated construction
as well as sustainable solutions.
Keywords: Bridges; Bridge-In-A-Backpack TM;
FRP composite arch tubes; Fast-track; Green
construction, Hybrid-Composite Beam; PreCoBeam;
Sustainability.
1.0 INTRODUCTION
Bridges are critical links in transportation networks
that should be maintained to remain safe and
functional during their service lives to enable
personal mobility and transport of goods to support
the economy and ensure high quality of life [Failure
of any crucial bridge not only results in precious loss
of lives, injury and huge property loss, but also affects
the economy of the region. For example, it was found
that the collapse of I-35W Mississippi River Bridge
(which was used by more than 140,000 vehicles per
Futuristic Composite Bridges
Dr. Subramanian NARAYANAN
Consulting Engineer
Gaithersburg, MD 20878
USA
drnsmani@gmail.com
Dr. N. Subramanian earned his PhD from
IIT, Madras in 1978. He worked in Germany
as Alexander von Humboldt Fellow during
1980-82 and 1984. He has 40 years of
professional experience which includes
teaching, research, and consultancy in India
and abroad. Dr. Subramanian has authored
25 books and more than 225 technical
papers, published in international and Indian
journals and conferences. He has won the
Tamil Nadu Scientist Award, the Lifetime
Achievement Award from the Indian
Concrete Institute (ICI) and the ACCE(I)-
Nagadi best book award for three of his
books. He also served as the past National
Vice-President of ICI and ACCE(I).
day) resulted in huge economic loss to Minnesota,
USA –about $17 million in 2007 and $43 million
in 2008]. But demands on most of the bridges have
been increasing annually because of growing traffic
volumes, higher loads, and aggressive environments
(e.g. deicing salts, frequent freeze- thaw cycles,
etc.). These conditions, coupled with the inadequate
funding allocated for maintenance, have led to the
accelerated aging and extensive deterioration of these
critical structures [Subramanian, 2011].
Bridges all over the world are not aging gracefully.
The recent US Federal National Bridge Inventory
showed that 65,605 bridges were classified as
"structurally deficient" and 20,808 as "fracture
critical”. Of those, 7,795 were both structurally
deficient and fracture critical and have to be replaced
sooner to avoid the risk of collapse. More than 30
percent of existing bridges have exceeded their 50-
year theoretical design life and are in need of various
levels of repairs, rehabilitation, or replacement.
Bridges constructed 50 years ago in other countries
like India should also be in a similar condition and
have to undergo major repair or replacement. Similar
to bridge rehabilitation, bridge replacement projects
require engineering resources for design, a substantial
and complex completion schedule, and considerable
costs. Life cycle costs and other economic factors
are usually considered when weighing rehabilitation
versus replacement costs. Since most of these bridges

2. 2 Volume 46 Number 2 June 2016 The Bridge and Structural Engineer
are still in service and carry huge amount of traffic,
conventional bridges or constructional methods can’t
be used for their replacement. A fast-track method
is necessary to quickly replace an existing bridge,
in a way that does not disturb the existing traffic.
Three futuristic composite bridge technologies
are described, which not only result in fast-track
construction but also in greener bridges with expected
life span of more than 100 years, as they are protected
from or not vulnerable to corrosion.
2.0 COMPOSITEARCHBRIDGESYSTEM-
BRIDGE-IN-A-BACKPACKTM
Engineers at Advanced Infrastructure Technologies,
Orono, Maine developed a hybrid concrete-composite
bridge, which will cut the cost of replacing many
existing bridges that also save time and raw materials.
This system was developed by Dr. Habib Dagher and
associates of the University of Maine’s Advanced
Structures and Composites Center in Orono, Maine,
USA and is distributed and marketed by Advance
Infrastructure Technologies (AIT), also located in
Orono, Maine. This system could be used to repair
or replace any existing deteriorating bridge, faster
and cheaper. This Composite Arch Bridge System,
known as Bridge-In-A-Backpack TM (BiaB), is
a lightweight, corrosion resistant system for short
to medium span bridge construction using FRP
composite arch tubes that act as reinforcement and
formwork for cast-in-place concrete. The concept of
this system is shown in Fig.1.
Fig. 1: Concept of the bridge in a backpack
The main advantage of this system is that the fiber
reinforced polymer (FRP) tubes (made of carbon and/
or glass fibers set in marine grade Vinyl Ester Resin),
which are made to arch are easily transportable,
rapidly deployable and do not require heavy
equipment or large crews needed to handle the weight
of traditional construction materials. These FRP tubes
are bent around arch forms and infused with resin in
the factory and removed from the form within hours
and sent to site for ready installation (see Fig, 2a). The
resin hardens in 4 hours, creating an arch that is twice
as strong as steel. The weight of hollow arch for a
305 mm diameter and 15.24 m span is approximately
91 kg, and the same arch with 381 mm diameter
would weigh 113 kg. Hence, two men can easily
lift and adjust the arches to their final position, thus
minimizing heavy trucking and eliminating heavy
equipment (see Fig. 2b).
Fig. 2: (a) FRP tubes are transported in light trucks and (b)
at site the tubes can be carried to the required place by hand
labour (AIT)

3. The Bridge and Structural Engineer Volume 46 Number 2 June 2016 3
The three functions of the FRP arch tubes are: (1)
Along with the decking, they act as stay-in place form
for concrete, thus eliminating the need for temporary
formwork, (2) They act as “structural reinforcement”
for concrete confinement (no steel rebars are used
in the superstructure), and enhances concrete
performance for safety and structural redundancy, and
(3) Provide environmental protection for concrete,
thus drastically reducing maintenance requirements.
The predominant structural components of the BiaB
system are the arches (ribs) of the bridge made of
FRP tubes, which are made rigid by filing them with
concrete. These ribs are spaced at a regular interval
and are configured to arch over the opening. The
installation consists of constructing the foundation,
setting the arches in the foundation at regular intervals,
and anchoring the arches in the concrete footing (see
Fig.3a to Fig. 3c). The first arch is set into place with
one person at each end to ensure arches are set in
perfect vertical and horizontal alignment. The next
arch is set and braced from the previous arch, using
the hardware provided by AIT to ensure alignment.
Fig.3: Anchoring the FRP arches in the foundation
Restraining is accomplished by using AIT provided
positioning hardware and fixing the arch end to the
abutment at the specified location/elevation. Wooden
spacers and ratcheting nylon straps can be used to
maintain the specified arch spacing prior to and
during FRP deck installation. After all the required
numbers of arches are anchored in the foundation,
the corrugated FRP decking is attached to the arches
using stainless steel fasteners along the spine of the
arch (see Fig. 4). A battery drill with clutch may be
used taking care not to strip holes when fastening the
deck. A panel of deck weighs about 10.5 kg/m, and a
12.2 m panel may weigh around 128 kg, necessitating
light equipment during deck installation. These sheets
transfer the weight of passing vehicles to the FRP
arches, after the bridge is commissioned.
Fig. 4: Attaching FRP decking to the FRP arches
The arches are then filled with self consolidating
concrete (SCC), through a hole at the top of each arch.
Note that SCC is selected due to its high flowability,
which does not require rodding or any vibration (see
Fig. 5). SCC is used with High Range Water Reducers

4. 4 Volume 46 Number 2 June 2016 The Bridge and Structural Engineer
(HRWR), or superplasticizers, to achieve high
flowability. Shrinkage Compensating Admixture
(SCA), a viscosity modifying admixture (VMA), a
hydration stabilizer (retarder) and 10 mm pea stone
aggregate are also specified in the mix (www.ctt.mtu.
edu). The company AIT usually provides standard
specifications for the concrete mix. A concrete pump
truck with a boom that can reach the apex of the
arch maybe used to fill the arches with concrete or a
traditional concrete bucket may be used.
(a) Pumping concrete into arches
(b) Funnel boxes direct flow and preveat overflow
Fig.5: Pumping of concrete into the FRP arches
The deck may then be concreted and cured for
24 hours (see Fig.6) After the arches have cured
for 24 hours, the headwall panels may be erected
and braced into position (A variety of headwall
options are available). Finally the structure may be
backfilled using maximum lifts of 300 mm, with the
installation of drainage, as appropriate (see Fig. 7).
After backfilling is completed to finish the grade,
the guardrails and paving is done to complete the
bridge (see Fig. 8). More details of installation of this
Bridge-In-A-Backpack TM bridge may be found in
AIT Installation handbook (AIT, 2011).
(a) Dry guniting of concrete deck
Fig.6: Concreting the Decking
Fig.7: Attachment of Headwalls, Wing walls, and Backfilling

5. The Bridge and Structural Engineer Volume 46 Number 2 June 2016 5
Fig. 8: Completed bridge
In 2009, an 8.5 m long bridge of this type was first
built by Advanced Infrastructure Technologies(AIT)
in Maine,USA, in just 11 days, instead of the usual
2 months, with an expected life of 100 years. The
“Bridge in a Backpack” serves three purposes: it is
a stay-in-place form for poured concrete; provides
exoskeleton reinforcement for existing bridges;
and serves as a protective layer for concrete. This
bridge is a greener alternative to concrete and steel
construction and saves money, reduces fabrication
time, lessens transportation costs, accelerates bridge
construction, and dramatically reduces lifetime
maintenance costs. Recently the State of Vermont
Agency of Transportation conducted an assessment
of this BiaB system, and found it to be greener than
conventional bridge systems [SoV-AoT, 2014].
This patented FRP system has been tested with
advanced structural characterization, predictive
modeling, and fatigue testing, along with
environmental durability tests for UV, fire, and
abrasion resistance. All designs are engineered to
exceed American Association of State Highway and
Transportation Officials (AASHTO) load standards
for single span bridges from 10 m to 20 m. In 2012,
AASHTO developed a standard for the Design of
Concrete-Filled FRP Tubes for Flexural and Axial
Members [AASHTO, 2012, www.countyengineers.
org]
This Composite Arch Bridge System has been used in
18bridgesinUSAandbeyond.Thisacceleratedbridge
construction technology has received the following
awards: (a) 2011 AASHTO TIG Focus Technology
award by the American Association of State Highway
and Transportation Officials (AASHTO), (b) 2011
Charles Pankow Award for Innovation by the
American Society of Civil Engineers (ASCE) (c) 2011
Engineering Excellence Awards by the American
Council of Engineering Companies (ACEC), and (d)
2010 Most Creative Product Award by the American
Composites Manufacturers Association (ACMA).
3.0 Hybrid –Composite Beam (HCB)
Another innovative bridge system, called the Hybrid-
Composite Beam (HCB®) and shown in Fig. 9, is a
structural member similar to a prestressed concrete
beam. The HCB® is a sustainable technology that
combines the strength and stiffness of conventional
concrete and steel with the lightweight and corrosion
resistant advantages of fiber reinforced polymers
(FRP). All of the strength and stiffness of the beam is
derivedfromconcreteandthehighstrengthgalvanized
pre-stressing strand. The FRP (Fiberglass Reinforced
Polymer) outer shell- made of quad weave fabric
with fibers that are horizontal (0o), vertical (90o)
and (± 45o), infused in an epoxy vinyl ester resin
matrix, provides shear strength and encapsulates the
tension and compression elements. The compression
element is concrete, which is in the shape of an arch
and carries compressive load internal to the beam.
The concrete used is SCC, which is pumped into a
profiled conduit (generally an arch) within the beam
shell (Hillman, 2012). The tension element is the pre-
stressing steel reinforcement that runs longitudinally
along the length of the beam and ties the two ends of
the concrete arch together. Essentially the HCB® is a
tied arch in a fiberglass box where 90% of the strength
is provided by steel and concrete. The encapsulating
FRP shell provides maximum protection for the steel
and concrete ensuring an extended service life and
minimal maintenance.
Fig. 9: Concept of Hybrid-Composite Beam

6. 6 Volume 46 Number 2 June 2016 The Bridge and Structural Engineer
Safety is inherently built into HCB® and the strength
capacity has been confirmed by full scale testing and
found to consistently exceed the code requirements.
By optimizing the inherent qualities of the three
components (FRP shell, SCC concrete in compression
and tension reinforcement), the HCB allows
construction professionals to build better structures
that are cost competitive, stronger and require no
additional training for their crews.
The underlying concept of the HCB® was conceived
by the bridge design engineer Mr. John Hillman, PE,
SE in the mid 1990's, who proposed that if a structural
member consisting of a concrete arch were tied at the
ends and encapsulated in a FRP shell, it would be
lightweight,strongandcorrosionresistant.Duringthe
next ten years, Mr. Hillman developed mathematical
modeling of the concept, and tested various small
scale prototypes. After small scale prototypes proved
successful, full scale, 10 m long beams designed for
Cooper E-80 railroad loading, were tested, which
proved the concept again. During 2006 and 2007, he
developed a commercially viable fabrication process
to build a 10 m railroad bridge. On November 7,
2007, the first known Hybrid Composite Railroad
Bridge was tested at the Transportation Technology
Center (TTCI) in Pueblo, Colorado, under live
railroad loading consisting of two locomotives and
28 fully loaded (145,150 kg each) gondola cars.
Once again, the beams performed according to
the model developed and refined over the years by
Mr. Hillman.
Since then, several highway bridges have been built
using the HCB®, the first one being the High Road
Bridge in Lockport Township, Illinois (see Fig. 10). It
was designed by Teng & Associates and constructed
by Herlihy Mid-Continent Company in 2008. The
17.4 m long, single-span ridge consists of six HCBs
supporting a conventional 200 mm thick reinforced
concrete deck. The second is the 9.5 m span bridge
over Route 23, Cedar Grove Township, New Jersey in
2009. The third highway bridge, the 165 m long, eight
span Knickerbocker Bridge in Boothbay Harbor,
Maine, was completed in June 2011. Details of these
bridges and other HCB® bridges may be found
from www.hcbridge.com. The design procedures
and installation sequence of HCB may be found in
Hillman, 2012. HCB® received the 2010 Award of
Excellence from Engineering News-Record.
Fig. 10: HCB® High Road Bridge – Lockport Township, IL –
17.4 m span, Aug 2008
The HCB® provides an effective method of
replacement of deteriorating bridges. Some of
the inherent benefits of this system are [Hillman,
2012]:
 Straightforward Production: The HCB® is
fabricated in a controlled shop setting without
any special equipment, expensive molds or
handling equipment. Glass fiber reinforcement
and steel tension reinforcement placement is done
quickly and efficiently, increasing product quality
and reliability while reducing fabrication/ labor
costs. Moreover, the HCB® does not mandate
any complex or new design criteria or changes in
construction methods.
 Reduced Shipping Costs: An empty HCB®
weighs only 10% of a comparable concrete beam
making it possible to ship up to six beams on
one truck as compared to one beam per truck for
precast concrete beams.
 Ease of Installation: The HCB® can be quickly
installed at the site with only light duty cranes
or excavators. HCBs do not require complicated
bracing and diaphragms as compared to typical
steel framed structures. The simplicity of
installation provides advantages to small, local
contractors as well as large construction firms.
 Sustainable: With a composite exterior, the
HCB® product has a high degree of protection
and is inherently corrosion-resistant, offering
service lives beyond 100 years with little or no
maintenance. The HCB® also uses 60% to 80%
less cement than a comparable concrete beam,
thus resulting in lesser carbon footprint. Also,
the closed mold, vacuum-assisted resin transfer
method (VARTM) used for the manufacture of the
composite shells is an environmentally friendly,

7. The Bridge and Structural Engineer Volume 46 Number 2 June 2016 7
zero VOC emission manufacturing process.
 Increased Safety: Since HCB® design is
controlled by deflection limits; strength capacity
typically exceeds code requirements by at least
10% to 60%. The significantly lower mass and
high strength energy absorbing FRP shell results
in a highly resilient structure under seismic
loads.
 Low Initial Cost: The HCB® utilizes higher-
cost composite materials only for the shell of the
beam. The primary strength and stiffness comes
from much lower-cost concrete and steel. This
combination results in a cost effective system
that is superior to conventional materials and can
compete economically on an installed, first cost
basis.
• Adaptable: The low weight of the HCB® makes
it a perfect component for prefabricated modular
construction. The rapid replacement of bridges is
becoming more important with increasing traffic
volumes. In the case of railroad installations, a
completed HCB® bridge superstructure is one
half the weight of a conventional precast concrete
structure. Prefabricated Railroad Bridge Modules,
including the concrete deck, ballast curbs and fall
protection can completely replace an existing
bridge in a matter of hours, not days.
4.0 Precobeam
The third system is a composite construction of
steel and concrete. Unlike regular composite bridge
construction, where a steel beam is connected
to the concrete slab by means of welded shear
connectors, in this system, half depth steel beam
cut with specially profiled web is connected to the
concrete T-beam, without any welding. Special
reinforcement detailing is adopted for the shear
transmission. This system is due to the research
projectcalledPreCoBeam(PrefabricatedComposite
Beam), funded by the Research Fund for Coal and
Steel (RFCS) of the European Community in 2003,
to develop a solution using prefabricated elements
that would be price-competitive, durable, suitable
for integral bridges and decks monolithically
connected to a substructure (in order to minimize
maintenance) and simple to erect. This concept of
PreCoBeam is shown in Fig. 11.
Fig. 11: Concept of PreCoBeam
The result is a composite beam with steel T-sections
that act as external reinforcement to a concrete top
chord. Steel T sections are obtained from rolled steel
profiles that are longitudinally cut, with a special
shape, into two T-sections. The special shape of
the cut embedded in concrete results in composite
dowels, which allow for effective shear transmission
between steel and reinforced concrete. A composite
dowel is formed by a specific cut steel plate (steel-
dowel) and the reinforced concrete that fills the
recesses in the steel plate (concrete-dowel). Different
types of cutting-geometries (See Fig. 12) have
been developed and were successfully introduced
to the market. The Fin-shape (SA) offers high load
bearing capacities (however, due to its asymmetric
geometry, forces in different directions will result
in reduced bearing capacities). In contrast to that the
Puzzle (PZ) and Clothoidal-geometry (CL / MCL)
have comparable bearing capacities for changing
directions of forces due to their symmetrical shape.
The Modified Clothoidal-shape (MCL) was found to
provide the highest fatigue resistance for cyclic loads
due to the smooth cutting radius. The cutting-process
may be accomplished by thermal autogenous cutting
technologies or by similar techniques that provide
comparable material characteristics and fatigue
behaviour for the cutting edge. The system was tested
at ultimate, serviceability and fatigue limit states in
Europe.

8. 8 Volume 46 Number 2 June 2016 The Bridge and Structural Engineer
(a) Different types of cutting geometries
(b) typical cutting-geometry for Clotholdal-shape (MCL);
grey parts are wasted
(c) Clotholdal shape after cutting
(d) Steel-sections alter cutting
Fig. 12: Different types of cutting-geometries and cutting
pattern of Clothoidal shape
The PreCoBeam concept combines the advantages of
prefabricated prestressed concrete beams (the upper
T of the section) with the steel girders (the lower T of
the section). As mentioned earlier, this prefabrication
method uses longitudinally cut-half rolled steel
beams. A concrete top chord is then added to each
element: this first layer is cast in the workshop. A
second phase layer is finally cast in-situ to complete
the cross section. There are many assembly types, but
the two often used types are the Duo- PreCoBeam
and Mono- PreCoBeam (see Fig.13). In Duo-
PreCoBeam, two halved steel T-beam sections are
positioned beside each other and filled with concrete,
which ensures a consistent torsional inertia, a more
slender section and that the shear connection is
nearer to the neutral axis. Mono- PreCoBeam uses
only one halved steel T-beam and calls for a deeper
reinforced concrete web. This option is more similar
to a prefabricated concrete section, but with better
bending moment resistance since the steel section
acts like “external reinforcement”. Due to the broad
variety of available rolled sections optimized solution
for a particular project can be realized; for example
using robust flanges for high stiffness or thick webs
for high longitudinal shear forces. As composite
dowels provide high fatigue resistance, they can be
used in road and railway bridges, subjected to cyclic
loads.
Fig. 13: Duo- PreCoBeam and Mono- PreCoBeam
The structural components of a typical mono-
PreCoBeam are shown in Fig.14 and the components
and detailing of typical composite dowel is shown in
Fig. 15. More details about the structural behaviour of
composite dowels, design recommendations, design
rules, example design of Simmerbach Bridge, and
construction details of PreCoBeam are given in the

9. The Bridge and Structural Engineer Volume 46 Number 2 June 2016 9
Design Guide, 2012. The static and fatigue design of
continuous shear connections of PreCoBeam based
on recent research is provided by Hechler et al., 2008.
1) Steel flange
2) Steel web
3) Composite dowel
4) Precast concrete web
5) Prefabricated concrete plate
6) In situ concrete plate
7) In situ Longitudinal reinforcement
8) Precast Longitudinal reinforcement
9) Transversal shear reinforcement
10) Confinement reinforcement
3
1
4
10
9 8 7 6 5
2
Fig. 14: Structural Components of a Typical Mono-
PreCoBeam
Notation of Composite-Dowel
1) Steel–Dowel
2) Concrete–Dowel
3) Reinforcement of Concrete–Dowel
4) Dowel–Bose
5) Dowel–Core
6) Dowel–Root
7) Dowel Top
8) Upper Reinforcement
9) Confinement Reinforcement
(a) Components of a Composite Dowel
(b) Typical reinforcement scheme for composite girders
Fig. 15 Components and detailing of composite dowel of
PreCoBeam
The advantages of PreCoBeam bridges include the
following:
 High safety factor for vehicle impact, especially
for bridges with only two girders (shock),
 Reduction of coating surface,
 Shear connection without fatigue problems,
 Simple steel construction nearly without any
welding,
 Sparse maintenance and easy monitoring
Bridge owners as well as general contractors evinced
interest in this innovative construction method
due to its effective concept, easy adoption, and the
advantages listed above. After it was developed and
tested in laboratories, more than 20 bridges (roadway,
railway and pedestrian) have been built throughout
Europe, demonstrating its viability as an alternative
for short-span bridge construction [Zanon et al.,
2014].
The 100 year old bridge in the Community of Pöcking
which links the village with Lake Starnberg, Germany
was reconstructed in 2004 using PreCoBeam
technology. This bridge is 16.6-m-long, two-span
deck with abutments and one intermediate pier
between the tracks. The total deck width is 10.5
m. As the reconstruction was taking place over an
existing railway line, a prefabricated solution to
minimize traffic disturbance was essential. The entire
deck width is supported by only three PreCoBeam
elements. Rolled sections HE1000M in S460M steel
grade (equivalent to w1000×300×350 in Grade 65)
were cut into two halves and recomposed in small
open box girders in full length of 32.5 m, and the
connection was made with puzzle shaped composite
dowels. Using the PreCoBeam technology reduced the
construction time significantly, and the three elements
were erected in one night[Zanon et al., 2014]. Next,
250 mm thick slab of concrete grade M35/45 was cast
in-situ to solidify the three elements- it has to be noted
that neither scaffolding nor formwork were required
for the construction.
The PreCoBeam technology has also been applied
to other bridges on Highway S7 in Poland between
2009 and 2012. Wide decks were used as continuous
beams over three or four spans, with a maximum
span of 18 m with a construction height of 830 mm
(slenderness L/22). PreCoBeam elements were made

10. 10 Volume 46 Number 2 June 2016 The Bridge and Structural Engineer
out of coupled HE1000A/B/M in S355 (equivalent to
w1000×300×272/314/350 in Grade 50 steel) with a
slab width of 2.4 m, and the prefabrication was done
directly on-site by the general contractor.
5.0 Summary
Transportation infrastructure is necessary for the
movement of goods and people across the country,
and also reflects the economic development of a
particular country. Many bridges constructed 50
years ago have exceeded their design age and have
to be replaced. In addition, several bridges have
deteriorated due to poor maintenance or corrosion.
Failure of bridges (as witnessed by the I-35W
Mississippi River Bridge in Aug. 2007) will affect
the local economy significantly. Hence it is important
to replace the ailing bridges quickly and efficiently.
Composite bridges are being used extensively, due
to their many advantages (Usual composite deck
construction consists of steel girders which support
a reinforced concrete slab. Composite action is
achieved by connecting both materials by shear
studs. Transverse bracing over supports provides
lateral restraint). Three futuristic composite bridges
viz., Bridge in a backpack [using FRP tubes filled
with SCC(Self Consolidating Concrete) as the main
load bearing elements], Hybrid-Composite Beam
(with a FRP shell housing an arch of SCC which
is tied at its ends by high strength galvanized pre-
stressing strand) and ProCoBeam [with a shear
composite dowel connecting bottom steel T- section
(with a specially profiled web) with the top concrete
T-section] are discussed in this paper, which result
in accelerated construction as well as sustainable
solutions. As these bridges are protected or
prevented from corrosion, they have more than 100
years of active life and result in greener solutions,
with significantly reduced CO2 emissions.
Acknowledgements
The author wishes to acknowledge the following
sources, from which the images are used in this
paper: The images of the Bridge-In-A-Backpack TM
(BiaB) system have been used from the presentation
available at www.countyengineers.org. Images of
Hybrid-Composite Beam are from www.nist.gov, and
the images of PreCoBeam are from the Design Guide,
2012.
References:
1. Advanced Infrastructure Technologies (AIT),
Bridge-in-a-Backpack Installation Handbook,
AIT, Orono Maine, March 18, 2011.
2. ASHTO, 2012, LFRD Guide Specifications
for Design of Concrete-Filled FRP Tubes
for Flexural and Axial Members, American
AssociationofStateHighwayandTransportation
Officials, First edition, 2012
3. Design Guide, 2012-Prefabricated Enduring
Composite Beams based on innovative Shear
Transmission, SSF Ingenieure AG, Germany,
119 pp. [http://www.stb.rwth-aachen.de/
projekte/2005/INTAB/docs/PRECO_English.
pdf]
4. HECHLER, O., BERTHELLEMY, J.,
LORENC, W. , SEIDL, G., and VIEFHUES,
E., “Continuous Shear Connectors in
Bridge Construction”, The 2008 Composite
Construction in Steel and Concrete Conference
VI, July 2008, Tabernash, CO, American Society
of Civil Engineers, 13 pp.
5. HILLMAN, J.R., “Hybrid-Composite Beam
(HCB®)-Design and Maintenance Manual”,
Prepared for The Missouri Department of
Transportation, Aug. 27, 2012, 41 pp. [http://
aii.transportation.org/Documents/BMDO/HCB-
design-maint-manual.pdf]
6. http://www.aitbridges.com/resources/
7. http://www.countyengineers.org/events/
annualconf/Documents/2013%20Presentations/
FRP%20Tube%20Bridge%20Clemens.pdf
8. http://www.ctt.mtu.edu/sites/ctt/files/
r e s o u r c e s / 2 0 1 3 b r i d g e c o n f e r e n c e /
katenhus&matheny-bridgeinabackpack.pdf
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