does stainless cost less? assessing the feasibility of...

Does Stainless Cost Less? Assessing the Feasibility of Stainless Steel as a Reinforcement Material for Bridge Decks on the Basis of Life-cycle Costing. Amanda Cope (Corresponding Author) Graduate Student Purdue University School of Civil Engineering West Lafayette IN, 47907 Ph: (765) 494-2206 Fax: (765) 496-7996 Email: [email protected] Samuel Labi Assistant Professor Purdue University, School of Civil Engineering 550 Stadium Mall Drive West Lafayette IN, 47907 Ph: (765) 494-5926 Fax: (765) 496-7996 Email: [email protected] Number of Words in Text: 4,247

Number of Tables: 7 (1,750 words)

Number of Figures: 5 (1,250 words)

Total Equivalent Number of Words: 7,247

ABSTRACT Bridge designers have a duty to identify and implement cost-effective practices so that designs can lead to minimal maintenance frequency and intensity (and hence least life-cycle preservation cost) over the facility life. The present paper compares the cost, benefits, and cost-effectiveness of using stainless steel to serve as the double mat material in bridge deck construction vis-à-vis using traditional epoxy-coated carbon steel. The material type for reinforcement of all other structural elements in the bridge superstructure and substructure are carbon steel. The methodology takes due cognizance of the initial agency costs, life-cycle agency costs, and the service life of stainless steel reinforcement vis-à-vis traditional epoxy-coated carbon steel. It is determined that using stainless steel will lead to significantly higher initial costs but drastically reduced costs over the bridge life cycle. In environments that are more vulnerable to the effects of corrosion, the relative benefits of stainless steel are expected to be even higher.

TRB 2009 Annual Meeting CD-ROM Original paper submittal - not revised by author.

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INTRODUCTION Background and Problem Statement Over the decades, engineers have come to realize that certain aspects of highway facility design can impair facility maintainability and thus can unduly increase the frequency and intensity of maintenance over the life of a facility. This issue is critical particularly in the current highway environment that is characterized by tighter budgets, increased traffic volumes, higher user expectations, aging facilities, and staffing limitations. The Federal Highway Administration (FHWA) has recognized this problem and duly encourages designers at various highway agencies to assess the maintenance implications of their designs. Over 15 years ago, a nationwide study conducted by the National Cooperative Highway Research Program (published as NCHRP Report 349) strongly suggested that highway design can and does influence maintenance levels of highway facilities and provided general guidelines for design for reduction of subsequent maintenance efforts (1). The release of that report encouraged other individual state highway agencies and researchers to pursue similar studies in their jurisdictions to take cognizance of local conditions and problems.

In this respect, the aspects of design that could be modified include geometrics and facility dimensions, and material types. The facility in question could be pavement, bridge, drainage facility, roadway appurtenance, and roadside appurtenance. The present study focuses on reinforcement for bridge decks.

(a) (b) Figure 1: Epoxy (a) and stainless steel (b) mats for bridge deck construction

Past research has identified corrosion of the reinforcement as the main cause of bridge

deck deterioration (2). The main mechanism of corrosion is the intrusion of chloride ions on the steel surface. The ambience of salts from deicing chemical applications and saline marine environment causes chloride ions to seep through concrete cracks to the reinforcing steel.

Corrosion is considered a serious structural problem because of the loss of deck strength and inability to counter high tensile forces in the structure. Furthermore, corroded steel exerts additional tensile forces on the surrounding material: a corroded steel bar can have a 3-6 times


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greater volume than a non-corroded bar (2). The increase in volume causes cracking and spalling in the concrete (Figure 2). In a large number of regions of the United States, Canada and other countries, deicing compounds are often applied to control snow and ice in the winter season. Thus, the corrosion problem will continue to persist far into the future until deicing chemicals are made to be devoid of chemicals that attack bridge structures. In the meantime, to reduce the corrosion caused by deicing, materials that are corrosion-resistant could serve as the solution to accelerated deterioration and thus for longer bridge service life. One of such materials is stainless steel.

The advantage of stainless steel over carbon or epoxy-coated steel is that it is far more resistant to corrosion. This is particularly important because corrosion is the major culprit for bridge deck deterioration in many countries and regions, and is particularly severe at coastal areas that have a saline environment. The added salt in the water and air accelerates corrosion when it comes into contact with the reinforcing steel. Even in non coastal but freeze regions, the use of saline deicing chemicals in the winter seasons has led to accelerated deterioration through corrosion of bridge deck reinforcement.

Figure 2: Effects of Bridge Deck Corrosion (Source: www.corrosioncost.com)

The Federal Highway Association conducted a 96-week testing of various rebar materials

in concrete slabs. The test was conducted to simulate marine and winter deicing materials subject to the concrete specimens. A saline solution was chosen to represent high salt concentrations from deicing salts and ponding was carried out for a certain period to replicate the high moisture content common in winter months (3). Upon completion of the experiment, the slab condition was documented. Table 1 presents the results. As the table indicates, the slabs


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with the stainless steel bars exhibited no damage while both the black carbon steel and the epoxy coated carbon steel resulted in cracking and rust staining.

Table 1: Reinforcing Steel Alternative Test Results (3)

Rebar Type Slab Configuration

Slab Condition after 96 Weeks

ASTM A615 Black Uncracked

All Slabs cracked Precracked

Six Different Epoxy-Coated Bar Types

Uncracked Some slabs cracked or exhibited rust staining

Precracked

Galvanized Bar Uncracked

All Slabs cracked Precracked

304 Stainless Steel Bar Uncracked No Damage Observed

Precracked Minor staining on concrete surface

316 Stainless Steel Bar Uncracked

No damage observed Precracked

There exists a number of technologies to protect against corrosion. A common practice

today is to coat the carbon steel reinforcement bars with a thin layer of epoxy. Epoxy coating can provide an additional 5 to 10 years of service life. However, it is extremely difficult to ensure quality control during the coating procedure and during subsequent reinforcement mat construction and aggregate pour (4). Special precaution is required to ensure the epoxy coating is not scraped or torn by aggregate or other material, or damaged from the sun. Another relatively new technology is the use of a fiber-reinforced plastic (FRP) reinforcement material which is non metallic and does not corrode. However the use of this material is fraught with several limitations. First, FRP has a relatively limited life span estimated at 65 to 90 years. Beyond this, the rapid strength loss of the material can cause catastrophic failure and therefore is unacceptable to designers. Other problems include a high initial cost, low elasticity modulus, impossibility of bending, and poor bond with cement paste (4).

Another promising technology is stainless steel. This differs from carbon steel in its chemical composition. In the manufacture of stainless steel, three chemicals – molybdenum, chromium, and nickel – are added (5). The chemical molybdenum is added to improve corrosion resistance. Common types of stainless steel include Type 304, Type 316, and Alloy 2205. The best grade of stainless steel to prevent corrosion is alloy 2205, however in non-marine climates type 316 is deemed acceptable (6). The type of stainless steel reinforcement that has typically been used used in non-marine climates are type 304 and 316 (3). It is important to note that past research and field studies has shown that the strength properties and constructability of stainless steel are comparable to traditional carbon steel (4, 6, 7). Table 2 compares strength properties of carbon steel and stainless steel. As such, carbon steel can be substituted by stainless steel without any adverse engineering or construction impacts.


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Table 1: Property Comparison between Carbon Steel and Stainless Steel

Rebar Type Yield Strength 0.2% Offset

min MPa

CARBON STEEL

Grade 40 300

Grade 60 420

Grade 75 520

STAINLESS STEEL

Grade 30 (Type 304, 316 300

Grade 420-Type 304 420

Grade 420-Type 316 420

Grade 520-2205 Duplex 520

As a reinforcement material, stainless steel has been used in coastal environments for

over 70 years. In 1937, the Progreso Port Authority, in Yucatan, Mexico, extremely aggressive chloride environment of the saltwater the bridge using stainless reinforcing rebar, AISI Type 304later, this bridge is in good condition and being usedsince its construction (4). Also, tform of stainless steel bridge reinforcement. These include the Belt Parkway York, the Woodrow Wilson Bridge in Washington DC, and the Haynes Inlet Slough Bridge in Oregon. These bridges were constructed fairly recentlydata is not readily available. However, recognizing that these research and technology related to brcloser scrutiny of their performance

Figure 3 presents maintenance schedules over life

Figure 3: Activity Profiles for

Stainless Steel Bridge

Carbon Steel Bridge

: Property Comparison between Carbon Steel and Stainless Steel (7)

Yield Strength 0.2% Offset

min MPa

Tensile Strength min MPa

Elongation Typical min

% in 2”

Coefficient of Thermal Expansion x10-6 C-1

Modulus

Elasticity

500 20 12

620 20 12

690 15 12

500 50 17

620 35 17

620 35 17

690 25 13

As a reinforcement material, stainless steel has been used in coastal environments for over 70 years. In 1937, the Progreso Port Authority, in Yucatan, Mexico,

aggressive chloride environment of the saltwater at a certain bridge sitbridge using stainless reinforcing rebar, AISI Type 304. At the present year, almost 70 years

later, this bridge is in good condition and being used regularly, without any major repair work Also, there are structures in the United States that have

ridge reinforcement. These include the Belt Parkway he Woodrow Wilson Bridge in Washington DC, and the Haynes Inlet Slough Bridge in

onstructed fairly recently and detailed long-term field However, recognizing that these bridges are on the cutting edge of

related to bridge decks long-term performance, a call is hereincloser scrutiny of their performance and their inclusion in national studies of bridge performance

presents maintenance schedules over life-cycle for a typical bridge in Indiana.

: Activity Profiles for Bridge Life-cycle for Stainless Steel and Traditional Steel Deck Reinforcement

5

Modulus of

Elasticity GPa

Magnetic

205 Yes

205 Yes

205 Yes

200 No

200 No

200 No

190 Yes

As a reinforcement material, stainless steel has been used in coastal environments for over 70 years. In 1937, the Progreso Port Authority, in Yucatan, Mexico, faced with an

at a certain bridge site, constructed At the present year, almost 70 years

, without any major repair work ructures in the United States that have used some

ridge reinforcement. These include the Belt Parkway Bridge in New he Woodrow Wilson Bridge in Washington DC, and the Haynes Inlet Slough Bridge in

field deterioration bridges are on the cutting edge of

, a call is herein made for and their inclusion in national studies of bridge performance.

cycle for a typical bridge in Indiana.

cycle for Stainless Steel and Traditional Steel


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At this point onward in the paper, the term “stainless steel bridge” refers to a bridge whose deck reinforcement material is stainless steel, while the term “traditional bridge” or “carbon steel bridge” refers to one whose deck reinforcement material is epoxy-coated carbon steel. In Figure 3, the expected service life of the stainless steel bridge is at least 100 years while that of the traditional bridge is 75 years. The activity profile or schedule for the traditional bridge is based on that of a concrete bridge presented in the Indiana Bridge Management System (8) and other similar literature (2); the activity profile for the stainless steel bridge is a hypothetical (albeit conservative) one based on research findings regarding the longevity of the stainless steel reinforcement material. These values from IBMS represent typical service lives based on average bridges and historical maintenance records in Indiana. For the stainless steel bridge, the conservativeness of the life-cycle activity profile is rooted in the findings of research and laboratory simulations that have determined that the stainless steel will be corrosion-free and still structurally sound well after 100 years (6). However, it is not certain that the other deck or bridge materials such as the concrete will last beyond a century. As such, a service life of 100 years is used for the stainless steel bridge whereas in realty (as suggested by the past research) it could be much more. Furthermore, the past research suggests that no bridge deck rehabilitation will be needed in the case of stainless steel. However, again, for the sake of playing devil’s advocate, it is herein assumed that the stainless steel bridge will require rehabilitation at years 50 and 75. The traditional bridge will require rehabilitation at year 20 and 60, and also deck replacement will be carried out at year 40. The differences in bridge preservation types and timings across the two alternatives translate into differences in agency cost and user cost at the time of the workzones as well as over the facility life. COST ANALYSIS Agency Cost Basic Material Cost

The relatively high cost of stainless steel is the major reason for the lack of its widespread use. On average, solid stainless steel cost is 2.5 to 4.0 times greater than that of carbon steel because stainless steel production involves more elaborate processing and handling compared to traditional steel (2). Furthermore, there is the issue of scale economies. Relatively lower volumes of stainless steel production (due to the low scale of its use) had led to a paucity of steel manufacturers that specialize in stainless steel bridge reinforcement production. Furthermore, with the price of steel rising in the past decade, users of stainless steel must overcome a much greater initial cost.

With the current fluctuating economic conditions and temperamental steel prices, it is difficult to find a consistent price for steel across many different sources. However, the price differential between carbon steel and stainless steel reinforcing has been fairly consistent. Most sources state that stainless steel will generally cost 2-5 times more than carbon steel. To account for possible fluctuations in steel prices, sensitivity analysis could be included in the cost estimation.

To offset the increasing cost, stainless steel has a longer service life than carbon steel. The following table illustrates price and service life differences. By choosing 2-layer solid SS rebar the service life can potentially be 8 times longer than black carbon steel and twice that of epoxy carbon steel.


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Table 3: Price and Service Life of Steel Reinforcement Types (2)

Corrosion Control Practice

Cost of Bar ($/lb)

Estimated Service Life (yrs)

Black Carbon Steel

$0.20 10

2-layer epoxy-coated rebar

$0.30 40

2-layer solid SS rebar

$1.75 75-120

Cost of Preservation The price differences in stainless steel and carbon steel is expected to reflect in the cost of the major bridge interventions, namely, initial construction, rehabilitation, and deck replacements which are needed for bridge life cycle costing. A study by Saito, Sinha, and Anderson developed statistical models for estimating the costs of bridge replacement (9) as follows:

964.0903.0 )()(155.0 DWBLBRTC =

Where BRTC = total bridge construction cost BL = bridge structure length, in ft. DW = bridge deck width (out-to-out), in ft.

The cost of bridge deck replacement and rehabilitation were calculated using average costs ($/sq.ft.) of bridge deck. The values were established from historical data on bridge deck replacement and rehabilitation contract costs. For bridge rehabilitation in the life-cycle activity profiles, various rehabilitation techniques were considered for analysis. Typically, bridges undergo a variety of maintenance procedures from simple patching to overlays. For the analysis in the present study, a Portland cement concrete overlay was used in analysis because (i) it is considered an appropriate treatment to rejuvenate the wearing surface and to repair any cracking or spalling damage (ii) it is generally difficult to predict the frequency or severity of areas needing patching for analysis and forecasting procedures. Table 4 presents the costs of the different rehabilitation types.

Table 4: Rehabilitation Technique Costs (2)

Type of Maintenance Average Cost ($/ft2)

Range of Costs ($/ft2)

Portland Cement Concrete Overlay

15.80 14-17.38

Bituminous concrete with Membrane

5.39 2.79-8.00

Polymer Overlay/Sealer 9.11 1.30-16.92

Bituminous Concrete Patch 8.37 3.63-13.11

Portland Cement Concrete Patch 36.72 29.93-43.59


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User Costs User costs comprise the costs of safety and delay associated with bridge construction and the cost of any detours due to functional obsolescence and structural deficiency. For purposes of this paper, it is assumed that the traditional and stainless steel bridge have no functional or structural problems so any difference in user costs are delay costs due to the workzones associated with their different life-cycle profiles. User costs comprise direct and indirect costs such as loss of time and additional gas if detour is used. Previous research has determined that workzones are the second largest contributor to non-recurring delay on freeways and principal arterials and are estimated to account for nearly 24 percent of all non-recurring delay. On a broader perspective, workzones cause 10% of the delay experienced in the entire United States and 80-90% of delay experienced in rural areas (10). In transportation asset life cycle analysis, it is typical that the user costs will far exceed the agency cost, and a critical issue becomes what should be the relative weight of agency to user cost. There seems to be no consensus in the literature regarding the relative weight between agency cost and user cost. In fact, a few researchers failed to address tehissue and thus proceeded to add agency costs directly to user costs thus implicitly assuming a 1:1 relative weight. To obviate this unresolved issue, the present paper carries out sensitivity analysis by considering different relative weights and investigating the outcome on the attractiveness of stainless steel relative to carbon steel. User cost of delay can be categorized cost of additional travel time and cost of additional fuel consumption. The travel time costs is incurred by the passengers. All other factors remaining the same, user cost of delay can be very different for a rural county bridge vis-à-vis an urban interstate because a workzone detours may be acceptable for the former but not for the latter. The equation for the cost of additional travel time and fuel are as follows: Travel time cost due to detour delay:

VPD x Estimated nr. of passengers per vehicle x Detour (mi) x Minimum hourly wage

Vehicle speed through detour

Travel time cost due to workzone delay:

VPD x Estimated nr. of passengers per vehicle x Delay time x Minimum hourly wage

Where Delay Time = Length of the workzone – Length of workzone

Speed through workzone Normal speed

Fuel consumption cost due to workzone delay is:

VPD x Detour Length (mi) x Fuel cost per mile

The sum of the costs is the daily user cost. It is assumed that the unit user cost will be the same for both the carbon steel and stainless steel bridges. This assumption is made because placement practices between the two materials are very similar and predicted to take the same period of time. However, the differences will reflect in the frequency of workzones in the life cycle – the “busier” life-cycle activity profile of carbon steel translates into more frequent workzones and consequently, higher user cost.


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Agency Benefits Agency benefits may be measured as the increase in facility life or performance. Table 5 presents the service lives of the various rehabilitation techniques.

Table 5: Rehabilitation Technique Service Lives (2)

Type of Maintenance Average Expected Life (years)

Range of Expected Life (years)

Portland Cement Concrete Overlay 18.5 14-23

Bituminous concrete with Membrane 10 4.5-15

Polymer Overlay/Sealer 10 6-25

Bituminous Concrete Patch 1 1-3

Portland Cement Concrete Patch 7 4-40

As the table indicates, maintenance procedure expected lives can range from 1-18.5 years. The severity of damage often dictates the type of maintenance required. For analysis, the Portland cement concrete overlay was chosen as the rehabilitation technique.

COST-EFFECTIVENESS ANALYSIS Theoretical Approach After establishing the cost and benefits associated with each of the two alternative material types, this paper proceeds to analysis the cost-effectiveness on the basis of the costs and benefits. Cost-effectiveness is best measured across the entire life cycle. This allow decision makers to answer questions such as which alternative yields the lowest total cost or maximum benefit over the project life and to address issues associated with the level of detail investigated in alternatives, and the impacts of different user costs in the long term (11). There are several criteria to determine the cost-effectiveness of a construction alternative. Net present value is not considered an appropriate criterion where alternatives have different life cycle lengths. However, a good criterion could be the ratio of the service life to net present value or the equivalent uniform annual cost (EUAC). EUAC, which gives the annualized cost of an alternative over a specified analysis period, can be used where alternatives have the same or difference service lives. The EUAC concept was used in this paper due to the differences in lengths of activity profiles of the traditional and stainless steel bridges. EUAC implicitly yields a value of cost-effectiveness and the benefits associated with stainless steel reinforcing can be determined as the reduction in EUAC relative to the traditional material.

Data Collection & Processing The data for estimating agency and user costs for the present paper spanned a long period of time. As such, to obviate the bias due to price inflation, all costs were converted to their year 2007 constant values using FHWA price indices (12) – commonly used in the engineering and construction management for estimating future costs of item. The standard equation for calculating any cost value at the year of analysis, is as follows:

BY

AYBYAY

I

ICC ⋅=


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Where CAY

= Cost of an activity in analysis year (in this case, 2002);

CBY

= Cost of the activity in base year;

IAY

= Price index corresponding to analysis year; and

IBY

= Price index corresponding to base year.

Results and Discussion To demonstrate the impact of implementing stainless steel reinforcing a sample bridge is herein analyzed. This bridge is representative of an average bridge constructed in Indiana. It is assumed that this construction is a complete bridge reconstruction. Table 6 shows the input data needed for analysis.

Table 6: Input Data for Analysis

Bridge Specific Input Category

Plan Specification Variable Input Category Plan Specifications

Bridge Location Howard County Interest Rate 4%

Bridge Type Prestressed Box Beam

Number of passengers per vehicle

1.8

Time for Initial Construction

120 days (estimation) Minimum hourly wage $13.43

Time to replace deck 60 days (estimation) Average Fuel Economy 23 mpg

Time to complete rehabilitation

21 days (estimation) Cost of Fuel $3.75/gallon

Bridge Length 148.66 ft Percent of user cost used in calculation

0-100%

Total Deck Width 49.33 ft

Vehicles per day 8527

Length of Detour 1.3 miles

Vehicle Speed through detour

30 mph

The above table can be developed for any standard bridge type by collecting from

construction plans or other transportation related documentation. The right half of the table represents other variables which are not dependent on the bridge in analysis but are more reflective of market and economic conditions. The input values of these variables can be changed to investigate the impact of those changes on the choice of reinforcing material.

The analysis shows that stainless steel is more desirable than carbon steel. When user costs are not considered, the EUAC for carbon steel is $69,400 while stainless steel is $54,810 (a ratio of 1.27). Thus EUAC is considerably lower for stainless steel even though that material type has a significantly higher initial construction cost. When 100% of user costs are considered, the feasibility of stainless steel reinforcing greatly increases. When considering user costs the EUAC is $170,082 and $125,810 for carbon steel and stainless steel, respectively (a ratio of 1.35). This implies that stainless steel is more cost-effective, over the life cycle, than the traditional material, and the economic superiority of stainless steel increases further when user costs are considered.


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The analysis was further extended for different interest rates. As Figure 4 suggests, higher interest rates stainless steel becomes

Figure

The relative weight of user cost (that is, what percentage of user cost should be considered in the analysis) was also varied to investigate its outcome of the results.0:1 weight and 100% implies 1:1 relatiuser costs, the more attractive the stainless steel option.

Figure 5: EUAC Results with Varying User Costs

was further extended for different interest rates. As Figure 4 suggests, higher interest rates stainless steel becomes an even more attractive alternative.

Figure 4: EUAC for Variable Interest Rates

The relative weight of user cost (that is, what percentage of user cost should be considered in the analysis) was also varied to investigate its outcome of the results.0:1 weight and 100% implies 1:1 relative weight. As seen in Figure 5, the greater the weight of user costs, the more attractive the stainless steel option.

: EUAC Results with Varying User Costs

11

was further extended for different interest rates. As Figure 4 suggests, at

The relative weight of user cost (that is, what percentage of user cost should be considered in the analysis) was also varied to investigate its outcome of the results. 0% implies

ve weight. As seen in Figure 5, the greater the weight of


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Once all input variables are selected, the analysis can be conducted for each individual bridge or for an entire network of bridges. For example, in the state of Indiana, a past study has established the anticipated date of reconstruction for all bridges on the state highway system. Table 7 presents the total number of bridges that will need reconstruction (replacement) and the total area of all bridge decks that will need deck replacement for each year between 2009 and 2015. Given such inventory and program, and the equivalent annual savings that can be expected from the use of stainless steel reinforcement for bridge decks, a rough amount of total network savings can be calculated. Table 7 presents the amount of such savings.

Table 7: Indiana Cumulative Savings by Incorporating Stainless Steel (13)

Year Number of bridges at the end of service life*

Bridge deck area in need of replacement* (sq. ft)

Annual Savings (0% user costs)

Cumulative Savings (0% user costs)

Annual Savings (100% user costs)

Cumulative Savings (100% user costs)

2009 29 178,154 $401,725 $401,725 $1,329,466 $1,329,466

2010 33 120,341 $459,113 $860,838 $1,488,116 $2,817,582

2011 47 349,767 $649,610 $1,510,448 $2,172,970 $4,990,552

2012 51 260,887 $707,740 $2,218,188 $2,322,295 $7,312,847

2013 7 27,337 $97,344 $2,315,532 $316,204 $7,629,051

2014 3 23,706 $41,430 $2,356,962 $139,115 $7,768,166

2015 4 17,088 $55,590 $2,412,552 $181,128 $7,949,294

It is seen that if user cost is not considered in the analysis, potential savings by 2015 will be over $2.4 million. If 100% of user costs were considered in the analysis, there will be nearly a $8 million savings by 2015. So the cost-effectiveness and savings associated with stainless steel, in only seven years, is evident.

The analysis in this study focused on the replacement of existing bridges. Further analysis can be carried out for new bridge construction and indeed new construction or rehabilitation of other asset types such as rigid pavements and roadway appurtenances that involve the use of steel. For example, the state’s log range plan suggests that Indiana will soon carry out a massive highway construction by extending Interstate 69 to the southern portion of the state. For the large number of bridges that dot the alignment for this project, stainless steel could be used for the bridge deck construction and this could earn the state significant savings in several millions of dollars not to mention elimination of non monetary or non quantifiable adverse impacts that are associated with frequent bridge repair work. CONCLUSIONS The present paper compares the cost, benefits, and cost-effectiveness of using stainless steel to serve as the double mat material in bridge deck construction vis-à-vis using traditional epoxy-coated carbon steel. It is determined that using stainless steel will lead to significantly higher initial costs but drastically reduced costs over the bridge life cycle, particularly when user costs are considered in the analysis. In environments that are more vulnerable to the effects of corrosion, the relative benefits of stainless steel are expected to be even higher. Also, the projected costs of stainless steel reinforcing are exceptionally high due to the theory of economy


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of scale. But as stainless steel becomes more commonplace as a viable reinforcement material and its production increases, it is expected that its costs will decrease. This will lead to reduced cost of stainless steel and even higher cost-effectiveness relative to the traditional material.

It is recommended that further research through laboratory and field testing be carried out to more accurately quantity the efficacy of stainless steel in terms of its life cycle activity profile. In this respect, the study of stainless steel as a viable alternative to traditional epoxy-coated carbon steel can be considered as one of the experiments in the long-term bridge performance research project. In the current national environment that is characterized by uncertainty of sustained funding, loss of knowledge due to incipient retirement of the baby boomer generation, and high user expectations, resolution of issues such as that of this paper can be useful to transportation agencies. ACKNOWLDEGMENTS The authors of this paper are grateful to Dr. Robert Frosch of Purdue University and Mr. Jaffar Golkhajeh of the Indiana Department of Transportation for providing valuable information towards the study. The contents of this paper reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of any governmental or private entity nor do the contents constitute a standard, specification, or regulation. REFERENCES 1. Anderson, R.W.G, Maintenance Considerations in Highway Design, NCHRP 349, Transportation Research Board, Washington, D.C., 1993. 2. Yunovich, M et al.. Corrosion Cost and Preventive Strategies in the United States. Appendix D: Highway Bridges. McLean : Office of Infrastructure Research and Development, FHWA-RD-01-156, 2001. 3. Lee, S. and Krauss, P. D. Long-Term Performance of Epoxy-Coated Reinforcing Steel in Heavy Salt-Contaminated Concrete. McLean : FHWA Office of Infrastructure R&D, 2004. 4. Schnell, R.E. and Bergmann, M.P. Improving tomorrow's infrastructure: extending the life of concrete structures with solid stainless steel reinforcing bar. 5. G.L. Huyett. Engineering Handbook. Technical Information. Minneapolis : G.L. Huyett, 2004. 6. International Molybdenum Association. Stainless Steel Reinforcement. International Molybdenum Association. [Online] [Cited: June 20, 2008.] http://www.imoa.info/_files/stainless_steel/StainlessSteelReinforcement.pdf. 7. FHWA. Corrosion Evaluation of Epoxy-Coated Metallic Clad and Solid Metallic Reinforcing Bars in Concrete. U.S. Department of Transportation FHWA-RD-98-153, 1998. 8. Sinha, K.C. Kepaptsoglou, K., Technical Manual for the Indiana Bridge Management System, West Lafayette, IN, 2000. 9. Saito, M., Sinha, K.C. and Anderson, V.L. Statistical Models for the Estimation of Bridge Replacement Costs. West Lafayette, 1990. 10. Chitturi, M.V., Benekohal, R. F. and Kaja-Mohideen, A. Methodology for Computing Delay and Users Costs in Work Zones. Transportation Research Board, Washington D.C., 2008.


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11. Gillespie, J. S. Estimating User Costs as a Basis for Incentive / Disincentive Amounts in Highway Construction Contracts. Charlottesville : Virginia Transportation Research Council, 1998. 12. FHWA. Improving Transportation Investment Decisions through Life-Cycle Cost Analysis. [Online] [Cited: July 29, 2008.] www.fhwa.dot.gov/infrastructure/asstmgmt/lccafact.htm. 13. FHWA. Highway Statistics. Federal Highway Administration.. U.S. Department of Transportation, Washington, D.C., 2003. 14. Labi, S., Rodriguez, M. M., and Sinha, K.C. Assessing preservation needs for a bridge network: a comparison of alternative approaches, Taylor and Francis Structure and

Infrastructure Engineering, pp. 221-235, 2008,


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