FHWA Resource Center
STRUCTURES TEAM
Evaluation
of the Economic Feasibility of Fiber-Reinforced Polymer (FRP) Bridge Decks
Sidharta Sahirman, Dr. Robert C. Creese, Bina R. Setyawati
Industrial and Management Systems Engineering Department
West Virginia University,
PO BOX 6070, Morgantown, WV 26506-6070
Phone: (304) 293 4607
Email addresses:
ssahirma@mix.wvu.edu, Robert.Creese@mail.wvu.edu,
bsetyawa@mix.wvu.edu
ISPA/SCEA International
Joint Conference
2003 Annual Meeting
Orlando, Florida, June 2003
Evaluation of the Economic Feasibility of Fiber-Reinforced Polymer (FRP)
Bridge Decks. Sidharta Sahirman, Dr. Robert C. Creese, CCE, Bina R. Setyawati.
Abstract
The application
of fiber-reinforced polymer (FRP) composites for bridge decks has been
successfully demonstrated. Regardless of the well known advantages of
FRP, one critical issue need to be justified. The important issue that
must be determined is the competitiveness of FRP bridge decks on a cost
basis in the future, compare to conventional methods such as SRC decks.
Life Cycle Cost is probably the best process to answer that issue. Life
Cycle Cost of FRP Bridge Decks includes the Initial Costs, Maintenance/Inspection/Repair
Costs, and Disposal Costs. The use of FRP composites as a replacement
for Steel Reinforced Concrete (SRC) bridge deck is expected to increase
service life and lower maintenance costs. The main problem encountered
is the initial costs of FRP bridge decks are significantly higher than
those from SRC. Hence, the initial costs of FRP decks must be reduced
to be cost competitive with the SRC decks on a life cycle cost basis.
The initial future costs can be estimated by utilizing improvement (learning)
curve theory and various improvement models to predict future costs are
under development. The various models apply the improvement theory with
different bases and the results obtained are varied. Two data sets were
investigated, and the preliminary results indicate that FRP decks should
become economically feasible within 10 years.
Authors Biography
Sidharta Sahirman
Education:
Master of Science in Industrial Engineering, The University of Pittsburgh,
2000.
Ph. D. student in Industrial Engineering, West Virginia University, Morgantown,
WV.
Research Interest:
Cost Estimating Models, Life Cycle Cost Analysis, Industry Waste Control.
Professional Societies:
Institute of Industrial Engineers
Association for the Advancement of Cost Engineering
Dr. Robert
C. Creese, CCE
Education:
Bachelor of Science in Industrial Engineering, The Pennsylvania State
University, 1963
Master of Science in Industrial Engineering, The Univ. of California at
Berkeley, 1964
Doctor of Philosophy with a major in Metallurgy, The Pennsylvania State
University 1972
Research Interests:
Cost engineering, cost estimating, and cost modeling applied to manufacturing
processes
Constructed facilities systems, health care systems, environmental waste
reclamation and recovery systems
Lean manufacturing
Professional Societies:
American Foundry Society, AACE, International (Association for the Advancement
of Cost Engineering), The American Society for Engineering Education ,
The American Society for Metals (ASM), The Iron and Steel Society of AIME
, Society of Manufacturing Engineers, American Welding Society, International
Society of Parametric Analysts, Society of Cost Estimating and Analysis
Bina R. Setyawati
Education:
Ph. D. student in Industrial Engineering, West Virginia University, Morgantown,
WV
Research Interest:
Neural Networks Applications, Applied Statistical Models, Cost Estimating
Models, Time Series Models, Production and Operation Research
Professional Societies:
Institute of Industrial Engineers
Association for the Advancement of Cost Engineering
1. Introduction
A fiber-reinforced polymer (FRP) composite is defined as a combination
of a polymer (plastic) matrix (either a thermoplastic or thermoset resin,
such as polyester, isopolyester, vinyl ester, epoxy, phenolic), a reinforcing
agent such as glass, carbon, aramid or other reinforcing material such
that there is a sufficient aspect ratio (length to thickness) to provide
a discernable reinforcing function in one or more directions 10. FRP
composite may also contain fillers, additives, and core materials that
modify and enhance the final product. Mechanical properties of the composite
depend on many variables such as fiber types, fiber orientations, and
composite architecture. The fiber is the critical constituent in composites,
and occupies 30-70% of the composite matrix volume 21.
The FRPs have very low weight and a high strength-to-weight ratio, high
tensile strength, and high fatigue resistance. They do not exhibit chloride
corrosion problems, which has been a continued challenge for bridge engineers.
This results in lower maintenance costs. It has also been observed that
FRP composites maintain their superior qualities even under a wide range
of temperatures 22. Other highly desirable qualities of composites are
high resistance to elevated temperature, abrasion, corrosion, and chemical
attack. Some of the advantages in the use of composite structure include
the ease of manufacturing, fabrication, handling, and erection, which
can result in short project delivery time 20.
FRP composite technology has been incorporated into the industrial world
for about 70 years. They have been the material of choice in the aerospace
industry since the 1960’s. However, only recently they have been
gaining popularity and getting accepted as a bridge material. In 1986,
the world’s first highway bridge using composite reinforcing tendons
was built in Germany. The first all composites bridge deck was demonstrated
in China. The first all composites pedestrian bridge was installed in
1992 in Aberfeldy, Scotland. In the U.S., the first FRP reinforced concrete
bridge deck was built in 1996 at McKinleyville, WV followed by the first
all-composite vehicular bridge deck in Russell, KS (1996).
The Federal Highway Administration (FHWA) has used FRP to build pedestrian
bridges, highway bridges, as well as for bridge strengthening and bridge
repairs. For more than 20 years FHWA has funded innovative bridge researches.
As a result, there are more vehicular bridge projects using FRP composite
materials in the United States than in any other country. In West Virginia,
i.e., there are 10 completed FRP deck projects and 3 other projects are
in design. The completed FRP deck projects in West Virginia include: (1).
Market St. Bridge, Ohio County, (2). Laurel Lick Bridge, Lewis County,
(3). Wickwire Run Bridge, Taylor County, (4). Hanover Bridge, Pendleton
County, (5). Boy Scout Camp Bridge, Raleigh County, (6). Katy Truss Bridge,
Marion County, (7). La Chein Bridge, Monroe County, (8). Montrose Bridge,
Randolph County, (9). West Buckeye Bridge, Monongalia County, and (10).
Howell's Mill Bridge, Cabel County 12.
As a new technology application, FRP bridge decks are hampered by a lack
of standards and experience, as well as high costs. The standards are
being developed, but widespread deployment will not occur until there
is more experience in their use and costs decrease sufficiently to support
this selection. More research is needed to determine if the technology
can become cost competitive for bridge decks.
Ehlen and Marshall suggested that despite FRP advantage over traditional
materials, economic and technical barriers hinder the introduction of
these new technologies 8. Tang and Podolny had a more optimistic view.
They suggested that FRP composite technology could be part of the solution
to the national bridge problem 22.
Composites can be used for the construction of an entire bridge structure,
as a decking material to be supported by concrete or steel girders, or
to rehabilitate current bridges. However, up to 1998, there had only been
approximately 80 bridge projects using FRP composite materials in the
world and most were built within the last few years.
The use of Fiber Reinforced Polymer (FRP) composites as a replacement
for Steel Reinforced Concrete (SRC) bridge deck has significant potential
advantages with increased service life and lower maintenance costs, but
the increased initial costs have made them infeasible on a life cycle
cost basis. The initial costs of FRP decks must be reduced to be cost
competitive with the SRC decks on a life cycle cost basis.
It is critical to note that FRP decks is not just a substitution of materials;
this also involves a major design change in the deck structure to apply
the FRP materials to meet the technological specifications in a cost effective
manner. There are several different designs being promoted and until the
best design is determined, the various alternatives make the decision
to use FRP more difficult.
2. Cost Analysis
There are two approaches
one could use for cost analysis, initial costs and life cycle costs. Basically,
initial costs are a subset of life cycle cost. When initial cost is the
major cost component, life cycle costing results will be similar to considering
only initial costs. However, when inspection, maintenance, and disposal
costs become dominant, life cycle costing should be utilized 5.
2.1. Initial Costs
Initial costs include
the material cost, component manufacturing, fabrication, assembly, shipment,
installation and testing costs. They reflect the largest costs in most
bridges and are appropriate for a majority of the applications 16.
When comparing conventional and composite structures on the basis of initial
costs, it’s clear that the direct initial costs favor conventional
structures. The higher initial cost of FRP bridge decks is expected due
to the high fiber and resins costs. However, the maintenance, rehabilitation,
demolition, and indirect costs favor composite structures. Projects with
long lives require that life cycle costing be utilized, as polymer decks
should have reduced rehabilitation and maintenance costs. In order to
be competitive, it is felt that the initial costs of FRP decks must be
approximately $ 40/square foot to be competitive with SRC decks.
2.1.1. Improvement
Curves
Learning curve was first applied in the aircraft industry, and translated
into an empirical theory in 1925. In 1936 T. P. Wright disclosed the results
of empirical tests of the learning curve and described a basic theory
for obtaining cost estimates based on repetitive production of airplane
assemblies. Since then, learning curves have been applied to all types
of work from simple tasks to complex jobs. Improvement curves are a more
appropriate name for learning curves. Improvement rate is the complement
of learning rate; thus if the learning rate is 90 percent, the improvement
is 10 percent.
There is three types of improvement curve models that are different based
on their definition of the dependent variable: the average time basis,
the marginal time basis, and the individual unit-time basis. The model
should be applied is the one that give the highest coefficient of determination
(R2) of its logarithmic linear regression. The two most important models
are Wright model (average time basis) and Crawford model (unit time basis.
The Wright Model first describe by TP Wright in 1936 is cumulative average
learning curve model. The theory states that as the total quantity of
units doubles, the average time per unit decrease by a constant percentage
18. The average time model specifies that the new cumulative average
time per unit (Y) will decrease by a constant percentage (I) as the cumulative
production (X) doubles.
Y= a X b (1)
Y=average cumulative time (cost) for X number of units
X= cumulative number of units produced
a = theoretical or actual value of the first unit
b= slope coefficient, -1 0
b=log (100-I/100)/log 2 (2)
I = improvement rate, percent
The unit time for the Wright Model can be approximated by:
Uw = (b+1) A Xb (3)
Where
Uw is the unit time (cost) for the Wright Model and this approximation
can be used when X is greater than 10.
The Crawford Model, an individual unit-time model, specifies that the
new individual time (Uc) per unit will decrease by a constant percentage
as cumulative production doubles
Uc=aXb (4)
Where
Uc=new individual time (cost) per unit
X=cumulative number of units produced
2.2. Life Cycle Costs
2.2.1. The Theory
Life Cycle Costing (LCC) is defined as "The total cost of the system
or product under study over its complete life cycle or the duration of
the period of study, whichever is the shorter 16". The study period
of LCC is defined as the length of time over which an investment is evaluated.
It depends on time horizon of investor or expected life of system. Three
key dates of study period are base date (beginning of study period), service
date (beginning of operational period), and end date (end of study period)
11.
Life Cycle Cost of FRP Bridge Decks includes the Initial Fabrication and
Erection Costs, Maintenance/Inspection/Repair Costs, and the Disposal
Costs. Maintenance includes material, equipment, labor and safety costs
during maintenance process (traffic control), bridge users costs and third
party costs. These costs will depend on the frequency and amount of maintenance
performed during the life cycle. The maintenance costs should include
the preventive maintenance, the scheduled maintenance, and breakdown maintenance.
Inspection includes the cost of the quality assurance procedures, testing,
and record maintenance. Repair is similar to maintenance costs, but done
for major items such as deck replacement, overlay replacement, and typically
is not performed on a regular basis 6.
It is suggested that the application of LCC at an early design stage will
greatly enhance system design and operation 15. Infrastructural projects,
such as bridges, which have high investment costs and long life expectations,
should use life cycle costing. It is necessary because of its high investment
costs, high cumulative maintenance costs and removal costs during the
life of the project 5.
The six main steps in an LCC analysis are (1) Identify feasible project
alternatives (2) Establish common assumptions (3) Identify relevant project
costs (4) Convert all dollar amounts to present value (5) Compute and
compare LCCs of alternatives, and (6) Interpret results 11. In order
to get appropriate analysis, assumptions should be clearly defined; the
most common ones are the definition of Life, Costs, Initial costs, Discounting
and Inflation, Taxation, and Benefits.
Since FRP is a new-technology material, it is required to compare this
technology with the conventional technologies. Ehlen and Marshall recommend
the following steps for calculating the life cycle cost of a new-technology
material vis-à-vis a conventional material. Those steps are:
(1) Define the project objective and minimum performance requirements
(2) Identify the alternatives for achieving the objectives
(3) Establish the basic assumptions for the analysis
(4) Identify, estimate, and determine the timing of all relevant costs
(5) Compute the LCC for each alternative
(6) Perform sensitivity analysis by recomputing the LCC for each alternative
using different assumptions
(7) Compare the alternative’s LCCs for each set of assumptions
(8) Consider the other project effects
(9) Select the best alternative.
In each alternative the user should use the same fixed discount rate and
the same study period. Implicit in any LCC analysis is the assumption
that every proposed alternative will satisfy the minimum performance requirements
of the project. These requirements include structural, safety, reliability,
environmental, and specific building code requirements. Step 6 is the
life cycle cost method is a fundamental part of assessing new construction
material. The costs and technical performance of new materials are intrinsically
uncertain; and this method must address this uncertainty. The inherent
cost uncertainty of materials and designs that are not in mainstream use
can be handled with Monte Carlo simulation 9.
Further, those researchers suggested using the LCC classification scheme
when evaluating new-technology material, mainly to make sure that all
costs associated with the project are taken into account in each alternative.
Three level cost classification proposed include: Level 1: Costs by LCC
Category (typically used are construction, operation/maintenance/repair,
and disposal); Level 2: Costs by the Entity that Bears the Cost (agency
costs, user costs, and third-party costs), and Level 3: Costs by Elemental
Breakdown (elemental costs, non-elemental costs, new-technology introduction
costs).
The life cycle cost of an alternative is represented by either (1) Present
Worth Cost or (2) Equivalent Uniform Annual Cost. Another approach might
be used is Benefit/Cost Ratio.
The equation to calculate the life-cycle cost of an alternative using
the first approach is as follows:
LCC (PV) = PVIC + PVOMR + PVD = Sn Fn (1+i’) - n , n=0 T
(5)
PVIC = Present Value of Initial Costs
PVOMR = Present Value of Operation, Maintenance, and Repair costs
PVD = Present Value of Disposal costs
F = sum of all expenditures at time n,
i’ = interest or discount rate corrected for inflation = i + f +
i*f (6)
i = interest or discount rate
f = inflation rate
T = total number of compounding periods or years.
Equivalent Uniform Annual Cost (EUAC) required the conversions of cash
flows to equivalent values that can be compared. It can be calculated
by first determining the present value life cycle cost as shown above
and then multiply by i’(1+i’)n/(1+i’)n-1
The generalized replacement model and the rehabilitation model are presented
in the following equations.
EUAC Replace=(A/P,i,N)R + S Gm(P/G,I,hm + 1)(P/F,I,gm - 1) + S
Fk (P/F,I,nk) + C (7)
EUAC Rehab=( EUAC Replace )(P/F,i,N’) + iD+C(P/A,I,N’) S
Gm(P/G,I,hm + 1)(P/F,I,gm - 1) + S Fk (P/F,I,nk) (8)
Where:
F=Single future expenditure for repair
D=Initial repair cost
N=life of bridge
N’=time to require replacement
n=time to future expenditure
R=Replacement structure first cost
C=Annual maintenance cost
G=annual increase in maintenance cost due to progressive deterioration
Benefit Cost Ratio method in principle examines the extra benefits of
advancing one improvement level to the next divided by the corresponding
extra costs. Agency benefits are defined as the present worth of future
cost savings to the agency because of a bridge expenditure 14. In life
cycle cost analysis, future costs must be discounted to a present worth
before they are combined with present costs.
2.2.2. LCC Cost Applications
2.2.2.1. FRP Bridge Applications
LCC on short-span FRP bridges by Nystrom et al. 16 have suggested that
total-FRP designs for this kind of bridge are not financially viable.
Short span bridges are small bridges with a span less than 10 meters,
which represent over half of the bridge applications nationally and are
critical to rural highways and city streets. They argued that without
particular intangible benefits to justify the premium, or new low-cost
materials are developed that will significantly lower the material cost,
this technology will not be cost competitive for the standard small bridge.
The LCC (PV) obtained based on equation (5) using discount factor 4%/yr
and expected life of 40 yrs and 60 yrs respectively for RC and FRP bridges
were $ 594/m2 for RC bridges, and $ 826/m2 for future FRP bridges. It
should be noted that the LCC analysis performed based on the assumptions
that total RC initial cost is $40/ft2 and total FRP initial cost is $70/ft2,
which are derived from the MRP bridges learning curve performed by the
authors.
This article implied that the cast-in-place reinforced concrete would
always be considerably less expensive than the FRP decks. The major difference
in the paper was the material costs, but some data was missing on the
material costs in the paper. The Saint James (Saint Francis Bridge in
Saint James) had a cost of $ 1,150/square meter ($ 107/square ft) versus
$430/square meter ($40/square ft) for the cast-in-place concrete bridge
and the FRP had a predicted future best cost of $ 750/square meter ($70/square
ft). The St. James was a prototype bridge and designs have reduced the
material consumption by approximately 30% or more during the last few
years for the pultrusion bridge decks. A major cost is the manufacturing
set-up cost (typically 72 hours) and costs for short runs are very high.
Standardized designs and long production runs should reduce costs another
20-25 percent because of reduced unit set-up times and lower scrap losses.
Improvements due to learning/experience, which is mentioned in this paper,
should reduce costs another 15-20 percent over a ten-fold production increase.
This would reduce the costs from the St. James values to $ 483-547 / square
meter when the technology is proven. Using the reported life cycle costs
in the paper of $164/square meter for concrete bridges and $76/square
meter for FRP bridges are considered, the total life-cycle costs become
$594/square meter for the cast-in-place concrete bridges and $559-623/square
meter for the FRP bridges. Thus FRP bridge systems should be competitive
with the cast-in-place concrete bridges. Savings could be greater as the
FRP designs have focused primarily on the deck and not on the other items
such as guardrails. Secondary advantages of shorter construction times
would provide additional benefits for the FRP designs 7.
2.2.2.2. FRP Bridge Deck Applications
Based on life-cycle costs analysis of three fiber-reinforced-polymer bridge
decks, the analysis indicates that one of these decks is cost effective
for a particular class of bridges and traffic levels 10. Further more,
life cycle cost analyses conducted by J. Muller International have shown
that FRP bridge decks used on conventional multi-beam overpass bridges
can reduce the life cycle cost of a bridge anywhere from 10 to 30 percent
over a 75 year design life. The major component of the cost savings is
a reduction in user costs associated with the increased speed of construction
and fewer traffic impacts due to a reduction in maintenance requirements.
The user costs were found to account for as much as 80 percent of the
life cycle cost of a bridge 3.
Nathan and Onyemelukwe studied a bridge deck replacement alternatives
for the Sunrise Boulevard movable bridge in Ft. Lauderdale, Florida 7.
LCC analysis is done on an existing steel grid deck and a proposed FRP
deck. Cost data for the steel deck as well as the FRP deck was obtained
from the Florida Department of Transportation and Strongwell Inc. respectively.
As the basis of calculation, they used 40 years steel deck life and 50
years FRP deck life, and a discount rate of 2%. The life cycle cost of
an alternative was represented by Present Worth Cost (5), Equivalent Uniform
Annual Cost (7,8) and Benefit/Cost Ratio.
The results based on present value and equivalent uniform annual cost
showed that rehabilitation or replacement for steel costs more than FRP
deck alternative. While B/C ratio for steel deck is higher, the difference
for both decks (steel 1.8 and FRP 1.7) is only 5%. It is believed that
B/C ratio will favor FRP if the assumption of FRP deck life is 60 yrs
rather than 50 yrs. No attempt can be made to figure this out since the
authors didn’t provide the necessary data to accomplish such effort.
The analysis suggested that in the long term FRP deck is cost effective.
Ehlen (1997) and Lopez-Anido (1998) performed LCC analysis of FRP bridge
decks vs. steel reinforced concrete. In their works, life cycle cost of
an alternative was represented in present value format (Equation 5). User
costs were calculated based on equations 9 and 10. The summary of their
analysis is given in Table 1.
Table 1. LCC analysis of FRP bridge decks
3. Initial Cost Feasibility
Study
Three different
models for evaluating the improvement rate were considered 20. The first
model studied the relationships between cumulative ft sq of FRP bridge
deck and average cost /ft sq. The second model examined cost/ft sq vs.
number of bridges. While the third model investigated the regression between
cost/ft sq and number of years FRP bridge decks applied. It is suggested
that the first model (cumulative ft sq of FRP bridge deck vs. average
cost /ft sq) is the most suitable model for estimating FRP bridge deck
future initial cost 20.
This approach is applied to the set data collected for WV Bridges (Table
2) and FRP bridges built in NY (Table 3) to get the comparison figures
of FRP bridge decks viability for different states. This issue is important,
since different states most probably will have different cost features
of FRP bridge deck projects, due to different pultrusion manufacturing
involved, different labor costs, etc. The value of $40/ft 2 was selected
to be the competitive price at which FRP decks would be competitive with
Steel Reinforced Concrete (SRC) decks. Based on the findings, the conclusion
is drawn.
Table 2. WV FRP Bridge
Deck Costs
(for accuracy -- see word doc for all references to tables or
figures)
Table 3. NY FRP Bridge Deck Costs Data
(see word doc for all references to tables or figures)
The cost equation
obtained for the new set of WV bridges data was C ($/ ft2) = 18023.12
* N -.59596. The equation for unit cost basis is: Cu ($/ft2) = 7282.06
* N-.59596. Total area of FRP bridge decks required to be built to get
the same unit cost as concrete is approximately 15,000 sq ft. Since the
average area of one bridge deck in WV is 1000 sq ft, the equilibrium point
will be reach after 15 bridge decks built. The corresponding improvement
curve is given in Figure 1; the complete results are provided in Table
4.
(see word doc for all references to tables or figures)
Figure 1. Improvement Curve for WV FRP Bridge Deck Cost and Cumulative
Deck Area
(see word doc for all references to tables or figures)
Table 4. Results
Obtained for WV FRP Bridge Decks
(see word doc for all references to tables or figures)
The cost equation obtained for NY bridges was C ($/sq ft) = 9067 * N -.4422.
This equation is translated to unit cost basis as: C ($/sq ft) = 5058
* N-.4422. Based on the equation obtained, it is calculated that the cost/ft
sq will reach the same level as concrete deck when total area of FRP bridge
decks built is approximately 57,000 sq ft. If the average area of one
bridge deck is 3500 sq ft, as the given data, the equilibrium point will
be reach after 17 bridge decks built. The R2 is very good for this model,
i.e. 0.99, which is slightly higher than the one for WV data (0.9887).
The improvement curve for the chosen model is given in Figure 2; the complete
results are provided in Table 5.
(see word doc for all references to tables or figures)
Figure 2. Improvement
Curve for NY FRP Bridge Deck Cost and Cumulative Deck Area
(see word doc for all references to tables or figures)
Figure 2. Improvement Curve for NY FRP Bridge Deck Cost and Cumulative
Deck Area
(see word doc for all references to tables or figures)
Table 5. Results Obtained for NY FRP Bridges
(see word doc for all references to tables or figures)
In a whole, it is
suggested that FRP bridge decks will be viable either in WV or NY in the
next 10 years. This assumption is based on a constant improvement rate
of 33.84 % for WV bridge deck projects and a constant improvement rate
of 26.40 % for NY bridge deck projects for the next 10 years as illustrated
in the above figures.
4. Conclusion
The issue that attempted to be answered in this paper is the competitiveness
of FRP bridge decks on a cost basis in the future with SRC decks. While
Life Cycle Cost is probably the best process to answer that issue, there
is not enough data to conduct such efforts. Initial LCC cost analysis
of FRP bridge deck is mixed. The main problem encountered is the initial
costs of FRP bridge decks are significantly higher than those from SRC.
Hence, the initial costs of FRP decks must be reduced to be cost competitive
with the SRC decks on a life cycle cost basis.
The initial future cost is estimated by utilizing improvement (learning)
curve theory. Two data sets were investigated, and the preliminary results
indicate that FRP decks should become economically feasible within 10
years.
References
1. Azama, S. 2000.
Application of learning curve theory to system acquisition.
2. Belkaoui, A. 1986.
The Learning Curve: a management accounting tool. Quorum Books, Westport,
Connecticut.
3. Cassity. 2000.
Fiber-Reinforced Polymer Bridge Decks.
4. Creese, R.C.,
M. Adithan, and B.S. Pabla. 1992. Estimating and Costing for the Metal
Manufacturing Industries. Marcel Dekker Inc., New York.
5. Creese, R. C.
1999. Overcoming Composite Cost Differentials by Life-Cycle Costing, Proceeding
of Conference on Polymer Composite: 110-116. Parkersburg, West Virginia,
19-21 April 1999.
6. Creese, R.C. and
S. Sahirman. Second Quarterly Report - June 2002. Characterization, Evaluation
and Implementation of Fiber Reinforced Polymer Composites for Highway
Infrastructure - Task 4. The Constructed Facilities Center, College
of Engineering and Mineral Resources, West Virginia University, Morgantown,
WV.
7. Creese, R.C. and
S. Sahirman. Third Quarterly Report - August 2002. Characterization,
Evaluation and Implementation of Fiber Reinforced Polymer Composites for
Highway Infrastructure - Task 4. The Constructed Facilities Center,
College of Engineering and Mineral Resources, West Virginia University,
Morgantown, WV.
8. Ehlen, M.A. and
H.E. Marshall. 1996. The Economics of New-Technology Materials: A Case
study of FRP Bridge Decking. NISTIR 5864, U.S. Department of Commerce.
9. Ehlen, M.A. 1997.
Life-Cycle Costs of New Construction Materials. Journal of Infrastructure
Systems, Dec. 1997: 129-133.
TRAINING
