ultimate limit state, the design is affected by the changes in the modulus of elasticity of ..... Thus, the effect of using the actual cross-sectional area of GFRP bar in ...
9th International Conference on Short and Medium Span Bridges Calgary, Alberta, Canada, July 15-18, 2014
DESIGN OF BRIDGE DECK SLABS USING GLASS FIBERREINFORCED POLYMER (GFRP) BARS OF DIFFERENT GRADES Ehab Ahmed University of Sherbrooke, Sherbrooke, QC, Canada. Brahim Benmokrane University of Sherbrooke, Sherbrooke, QC, Canada. ABSTRACT The use of glass fiber-reinforced polymer (GFRP) reinforcement as alternative reinforcement has become of interest to overcome the problem of steel corrosion and associated deteriorations. Since the design of FRP reinforced concrete (FRP-RC) sections is governed by serviceability limit state rather than ultimate limit state, the design is affected by the changes in the modulus of elasticity. This paper investigates the effect of using GFRP reinforcing bars of different grades on the required reinforcement amount for concrete bridge deck slabs designed according to the Canadian Highway Bridge Design Code (CAN/CSA S6S1-10) using the empirical and the flexural design methods. The investigation includes GFRP of three different grades, Grade I, Grade II, and Grade III (CAN/CSA S807-10) with a corresponding modulus of elasticity of 42.5, 52.5, and 62.6 GPa, respectively. The investigation includes a wide range of effective girder spacing (1.5 to 3.5 m) and three different thicknesses (175, 200, and 225 mm). It includes a cantilever overhang of 1.5 m long as well. In addition, the effect of the difference between nominal and actual cross-sectional area of FRP bars on design of FRP-RC sections, if any, is also evaluated. 1. INTRODUCTION The corrosion of steel reinforcement and related deterioration of concrete infrastructure is one of the major problems facing the construction industry. The U.S. Federal Highway Administration (FHWA) released a break-through study entitled “Corrosion Costs and Preventive Strategies in the United Stated” on costs associated with metallic corrosion (Koch et al. 2002). The total annual estimated the direct cost of corrosion in estimated about $276 billion which is approximately 3.1% of the nation’s gross domestic product (GDP). The study also conservatively estimated the indirect costs to be equal to the direct costs which bring the costs of corrosion to about 6% of the GDP. In Canada, the direct costs of corrosion are estimated as $23.6 billion which represents about 2-4% of the global national product (GNP) (Ghali et al. 2007). In addition, Transportation for America (2013) reported that one out of every nine bridges that U.S. motorists cross each day is likely to be deteriorating to some degree. Nearly 70,000, or 11.5%, of the bridges nationwide are rated “structurally deficient” according to government standards. Although there is a multitude of method for minimizing the devastating effects of steel corrosion, using the corrosion-resistant fiber-reinforced polymer (FRP) composites materials eliminates the potential of steel corrosion. This cutting-edge technology showed promise as a way to further protect bridges and public infrastructure and extend their service life. During the last few years, there has been an exponential increase in the number of projects across Canada particularly in designing and constructing concrete bridges with GFRP reinforcement. Recently, there have been many successful applications using GFRP reinforcing bars as main reinforcement in bridge deck slabs and barrier walls (Benmokrane et al. 2006&2007; Drouin et al. 2011; Ahmed et al. 2014). Figure 1 shows one of the recent applications of GFRP bars in a bridge deck slab (Ahmed et al. 2014). Since the design of FRP-reinforced concrete sections (FRP-RC) is governed by serviceability limit state rather than ultimate limit state, the design is affected by the changes in the modulus of elasticity of the FRP. In a previous
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investigation, Ahmed and Benmokrane (2010) investigated the use of two GFRP products in the design of GFRP bridge deck slabs using two concrete strengths. Through this investigation, it was concluded that increasing the modulus of elasticity of GFRP bars reduces the required reinforcement amount. This paper investigates the effect of using GFRP reinforcing bars of different grades on the required reinforcement amount for concrete bridge deck slabs and cantilever overhangs designed according to the Canadian Highway Bridge Design Code (CHBDC CAN/CSA S6S1-10) using the empirical and the flexural design methods for the interior deck slabs and the flexural design method for the cantilever overhangs. In addition, the effect of the difference, if any, between the nominal and actual cross-sectional area of the FRP bars on the design of FRP-RC sections is also evaluated.
Figure 1: A recent application of GFRP bars in a bridge deck slab (Ahmed et al. 2014) 2. DESIGN APPROACHS IN THE CANDAIAN HIGHWAY BRIDGE DESIGN CODE CAN/CSA S6 The Canadian Highway Bridge Design Code (CHBDC CAN/CSA S6S1, 2010) provides the following two methods for the design of concrete bridge decks reinforced with steel and FRP reinforcing bars (Section 8 and Section 16): 2.1 The Empirical Method As stated by the CHBDC (CAN/CSA S6S1, 2010) Clause 8.18.4.1, the empirical method is applicable for that portion of the deck slab which is of nearly uniform thickness and bounded by the exterior supporting beams. However, they have to meet the conditions specified in Clause 8.18.4.1 in the CAN/CSA S6S1 (2010). These conditions are: (a) The deck slab is composite with the supporting beams, which are parallel to each other, and the lines of supports for the beams are also parallel to each other, (b) The ratio of the spacing of the supporting beams to the thickness of the slab is less or equal to 18.0. The spacing of the supporting beams used in calculating this ratio is taken parallel to the direction of the transverse reinforcement, (c) The spacing of the supporting beams does not exceed 4.0 m and the slab extends sufficiently beyond the external beams to provide full development length for the bottom transverse reinforcement, (d) When the supporting beams or their lines of supports are not parallel to themselves, engineering judgment shall be used to determine whether the empirical design method for the design of the deck slab is to be adopted. In addition, for the empirical design method to apply, a full-depth cast-in-place deck slab should satisfy the conditions specified by Clause 8.18.4.2 (for steel reinforcement) and Clause 16.8.8.1 (for FRP reinforcement) in addition to those of Clause 8.18.4.1. Clause 16.8.8.1 “Design by empirical method” mandates the following: (a) The deck slab contains two orthogonal assemblies of FRP bars with the clear distance between the top and bottom transverse bars being a minimum of 55 mm.
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(b) For the transverse FRP bars in the bottom assembly, the minimum area of cross-section in mm2/mm is 500ds/EFRP, where ds is the distance from the top of the slab to the centroid of the bottom transverse FRP bars (mm) and EFRP is the mean modulus of elasticity of FRP bars (MPa). (c) Longitudinal bars in the bottom assembly and both the transverse and longitudinal bars in the top assembly are of GFRP with a minimum of 0.0035. It can be noticed that the reinforcement amount is directly related to the cross-section and the stiffness of the FRP bars with is represented by the modulus of elasticity (EFRP). Thus, over-estimating the deck thickness will result in increasing the reinforcement ratio. On the other hand, using higher modulus GFRP reinforcing bars will contribute to reducing the reinforcement amount which will contribute to reducing the total cost. 2.2 The Flexural Method In the flexural design method, concrete deck slabs shall be analyzed for positive and negative bending moments resulting from loads applied on the slabs. The analysis shall consider the bending moments induced in the longitudinal direction that agree with the assumptions used in the analysis of the transverse bending moments. The cantilever portions of concrete deck slabs shall be analyzed for transverse negative bending moments resulting from loads on the cantilever portions of the slabs or horizontal loads on barriers and railings. The cantilever portions of concrete deck slabs may be analyzed using Clause 5.7.1.6.1 while the deck slabs are analyzed using Clause 5.7.1.7.1. The design of sections, however, should be conducted according to Section 8 when steel bars are used and Section 16 when FRP reinforcing bars are used. When the concrete deck slabs are designed according to the flexural design method for CL-625 truck, the design bending moments are determined based on a maximum wheel load of 87.5 kN. The design service load for the deck slabs is taken as 1.4 × 0.9 × 87.5 = 110.25 kN, where 1.4 is the impact coefficient and 0.9 is the live-load combination factor, while the design factored load is taken as 1.4 × 1.7 × 87.5 = 208.25 kN, where 1.7 is the liveload combination factor. According to Section 16 in the CHBDC (CAN/CSA S6S1, 2010), the design of flexural members reinforced with GFRP bars should consider the following: (a) For concrete components reinforced with FRP bars or grids, the overall performance factor, J, shall be at least 4.0 for rectangular sections and 6.0 for T-sections. (Clause 16.8.2.1). (b) The factored resistance, Mr, shall be at least 50% greater than the cracking moment, Mcr. This requirement may be waived if the factored resistance, Mr, is at least 50% greater than the factored moment, Mf. If the ultimate limit state (ULS) design of the section is governed by FRP rupture (under reinforced section), Mr shall be greater than 1.5 Mf. This condition may be waived if Mr > 1.5 MULS. (Clause 16.8.2.2). (c) When the maximum tensile strain, SLS, exceeds 1500 , the crack width has to not exceed 0.5 mm for members subjected to aggressive environment. (Clause 16.8.2.3). (d) The maximum stress in FRP bars under loads at service limit state (SLS) shall not be more than FSLS fFRPu, where FSLS is 0.25 for GFRP bars. (Clause 16.8.3). (e) The longitudinal reinforcement provided by Clause 8.18.7 of the CAN/CSA S6S1 (2010), both top and bottom when the main reinforcement is perpendicular to traffic shall be 120/(S)0.5, up to a maximum of 67% of the transverse reinforcement. In addition, as mandated by Clause 16.8.8.2 the spacing of the reinforcement in each direction shall not exceed 300 mm and the diameter of the reinforcement shall not be less than 15 mm. It should be mentioned that the CHBDC (CAN/CSA S6S1, 2010) states that concrete deck slabs (other than their cantilever portions that are proportioned in accordance with the empirical design method of Clause 8.18.4 for the CL-625 Truck) need not be analyzed for transverse bending moments due to live load. Thus, if the bridge deck slab meets the requirements of the empirical method, it could be deigned accordingly. Furthermore, based on the authors’ experience in this topic, the GFRP-RC bridge deck sections will be overreinforced (reinforcement ratio>balanced reinforcement ratio). Thus, these sections are expected to meet the deformability requirements of the CSN/CSA S6S1 (2010). However, calculations may be conducted to verify the deformability performance factor, J. 525-3
3. BRIDGE DECK SLABS AND REINFORCING MATERIALS To achieve the objectives of this investigation, interior concrete bridge deck slabs and the cantilever overhangs were used. Figure 2 shows the geometry presents the effective span definition according to the CAN/CSA S6S1 (2010).
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Figure 2: Definition of effective span according to CHBDC CAN/CSA S6S1-10 For the interior spans between the girders, the effective spacing (Se) ranged from 1.5 to 3.5 m and three different thickness were used, namely 175, 200, and 225 mm. The 175 mm is the minimum thickness provided by the CHBDC while the 200 and 225 mm are two common thicknesses. The design moments corresponding to each effective spacing (Se) were calculated using the flexural design method and reported in Table 1. The design moments were calculated considering the actual slab thickness and 80 mm of asphalt and the wheel load of CL-625 standard truck. It should be mentioned that reported values in Table 1 correspond to the 200 mm thick slabs, for simplicity, but the design was conducted considering the actual values corresponding to the thickness (175, 200, and 225 mm). On the other hand, cantilever overhang of effective span (Sp) = 1.5 m long was designed using the three thicknesses as the interior spans (175, 200, and 225 mm). The design moments were calculated using the flexural design method considering the CL-625 truck (Clause 5.7.1.6.1.1) and the railing load of PL-2 barriers (Clause 5.7.1.6.3). The notation for the design of the overhang is shown in Figure 3. The design moments are reported in Table 1. P 0.3 m t1
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Figure 3: Notation for cantilever moment according to CHBDC CAN/CSAS6S1-10 The interior deck slabs and overhangs were designed using glass fiber-reinforced polymer (GFRP) bars of three different grades. The bars were classified according to the CSA S807 (2010) as Grade I, Grade II, and Grade III. The 525-4
moduli of elasticity of these GFRP bars were 42.5, 52.5, and 62.6 GPa, respectively. These values are common properties for GFRP bars from the Canadian manufacturers. Table 2 lists the properties of the used GFRP bars. All the used bars were of sand-coated surface with bond coefficient factor, kb, equal to 0.8. Table 1: Girder spacing and design moments of the deck slabs of the four bridges Effective spacing Bridge deck slab Design moment at service Design moment at between girders, thickness limit state ultimate limit state se (m) (mm) MSLS (kN.m) MULS (kN.m) 1 1.5 19.58 36.35 2 2.0 24.81 45.74 3 2.5 30.28 55.43 175; 200; 225 4 3.0 35.98 65.42 5 3.5 41.92 75.72 Overhang Sp = 1.5 m 41.98 97.59 Dead load is calculated assuming concrete density of 23.5 kN/m3 and using 80 mm of asphalt of 24 kN/m3 density. Design moments according to an average thickness of 200 mm (for simplicity). Bridge Model No.
Table 2: Mechanical properties of sand-coated GFRP bars used in this investigation Type of GFRP bars Grade* Nominal Specified tensile strength, Tensile modulus of elasticity, area** (mm2) fFRPu (MPa) EFRP (GPa) G-I I 199 940 42.5 G-II II 199 1130 52.5 G-III III 199 1184 62.6 * According to the CAN/CSA S807-10 (2010). ** Cross-sectional area of No. 15 GFRP bars (15.9 mm diameter) according to the CAN/CSA S807-10 (2010). 4. DESIGN RESULTS 4.1 The Empirical Method Considering the three thicknesses provided in Table 1 and the FRP material properties presented in Table 2, the bridge deck slabs were designed according to the Empirical Method of the CHBDC CAN/CSA S6S1. The GFRP reinforcement amount for the three thicknesses employed in this investigation (175, 200, 225 mm) using the three GFRP types (EFRP = 42.5, 52.5, and 62.6 GPa) is presented in Table 3. The amount of the GFRP reinforcement is calculated as 500ds/EFRP which depends on the slab thickness and the elastic modulus of the reinforcement. The relationships between the amount of the GFRP reinforcement and the modulus of elasticity of the GFRP bars for the three slab thicknesses are shown in Figure 4. From this figure, it can be noticed that, the higher the slab thickness, the higher the GFRP reinforcement amount. Furthermore, using G-II and G-III bars with higher modulus than G-I reduced the required GFRP reinforcement amount in the bottom transverse reinforcement by 19 and 32%, respectively. It should be mentioned that the concrete strength does not have any effect on the GFRP reinforcement amount calculated using this method (empirical method). In addition, since the reinforcement amount is dependent on the cross-sections, it should be noted that increasing the concrete sections will necessitate more GFRP reinforcement. Table 3: Required GFRP reinforcement determined using the empirical method ds Other directions Bottom transverse GFRP reinforcement (mm2/m) (mm) (mm2/m) G-I G-II G-III 175 129 1425 1153 967 613 200 154 1719 1391 1167 700 225 179 2013 1630 1367 788 % of save in the GFRP amount Reference 19% 32% Slab thickness (mm)
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The design of all deck slabs using the flexural method was governed by the crack width limit which is equal to 0.5 mm. Thus, as expected, increasing the modulus of elasticity of the GFRP reinforcing bars, EFRP, decreased the required transverse reinforcement (top and bottom) as shown in Figures 5 and 6.
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Figure 6: Area of the transverse GFRP reinforcement versus the modulus of elasticity of the GFRP bars
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From the relationship between the effective girder spacing and the calculated GFRP transverse reinforcement area shown in Figure 5 it can be noticed that the reinforcement amount was proportional to the girder spacing. The higher the effective girder spacing, the higher the GFRP reinforcement amount. This is referred to the higher design moment when the effective spacing increases. When the spacing increased from 1.5 m to 3.50 m the increase in the reinforcement amount was about 62%, on average, for the slab thickness of 175 mm. This increase was about 56%, on average, for slab thickness of 225 mm and average of 54% for the three considered thicknesses. In addition, the reinforcement amount was proportional to the modulus of elasticity of the GFRP bars. Increasing the modulus of elasticity from 42.5 to 52.5 GPa reduced the GFRP amount by an average of 10% while increasing it to 62.6 GPa reduced the GFRP amount by an average of 20%. Furthermore, as Figures 5 and 6 show, increasing the thickness of the deck slabs contributed to reducing the required amount of the transverse GFRP reinforcement. Table 4 provides the ratio between the GFRP reinforcement amount calculated by the empirical method and that calculated using the flexural design method. By comparing the amount of GFRP reinforcement calculated with the flexural method and that calculated with the empirical method it can be noticed that: For deck slabs with 175 mm thickness, the empirical method yielded lower reinforcement amount than the flexural method for the all considered deck slabs. On contrary for deck slabs with 225 mm thickness, the empirical method yielded higher reinforcement amount than the flexural method for the all considered deck slabs. For deck slabs with a thickness of 200 mm and effective girder spacing Se=2.0 to 2.5 m there was a good agreement between the amount of the transverse GFRP reinforcement calculated using the empirical and flexural design methods. For the other longitudinal and top transverse reinforcement, the empirical method always yields less areas of reinforcement (0.35% area of the concrete).
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Table 4: AFRP Empirical/AFRP Flexural ratio AFRP Empirical/AFRP Flexural Se=1.5 Se=2.0 Se=2.5 Se=3.0 0.98 0.85 0.75 0.66 1.35 1.17 1.04 0.93 1.79 1.55 1.36 1.22 0.89 0.77 0.68 0.61 1.14 1.07 0.96 0.86 1.60 1.42 1.25 1.12 0.82 0.72 0.63 0.57 1.14 0.99 0.88 0.79 1.48 1.30 1.16 1.05
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Average 0.81 1.12 1.48 0.74 1.01 1.35 0.69 0.95 1.25
4.3 Design of the Cantilever Overhang The overhang was designed according to the flexural method using the 175, 200, and 225 mm thickness and using the material properties shown in Table 2. Generally, increasing the slab thickness of the overhang significantly reduced the GFRP reinforcement amount. The design of the overhang was governed by the flexural capacity for the 175 and 200 mm thickness when GFRP bars of any grade were used. Accordingly, the corresponding crack widths were less than the design limit (0.5 mm). On the other hand, the design of 225 m-thick overhang was governed by the crack width limit (0.5 mm). Figure 7 shows the relationship between the amount of GFRP reinforcement and the modulus of elasticity of the GFRP bars. As expected, increasing the modulus of elasticity of the GFRP reinforcing bars, EFRP, decreased the required reinforcement. The use of GFRP bars of low modulus of elasticity (such as Grade I) with the minimum thickness of 175 mm yielded very high reinforcement amount to satisfy the flexural strength (factored moment). Increasing the modulus of GFRP to Grade III reduced the GFRP reinforcement by 33%. Increasing the thickness to 200 mm enhanced the
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design and significantly reduced the required GFRP reinforcement amount as shown in Figure 7. The use of Grade III bars in case of 200 and 225 mm thick slabs reduced the required reinforcement amount by 28% and 22%, respectively. The effective design of the overhang should consider the thickness and the modulus of elasticity of the GFRP reinforcement to satisfy the flexural strength and the crack width limit (serviceability limit). Reducing the thickness may cause the design to be governed by the flexural capacity which necessitates more reinforcement than what is needed to satisfy the crack width limit of 0.5 mm. The 200 and 225 mm look more reasonable thicknesses for the bridge overhangs of length around 1.5 m.
Figure 7: Area of the GFRP reinforcement versus the modulus of elasticity of the GFRP bars 5. EFFECT OF BAR DIAMETER (CROSS-SECTIONAL AREA) In determining the mechanical properties of the FRP bars according to the relevant test methods, the manufacturers often use the nominal cross-sectional area such as those of CSA S807-10 (2010) or ACI 440.6M-08 (2008). The actual cross-sectional areas in many cases are larger than the nominal ones. Consequently, using the actual crosssectional area leads to lower modulus of elasticity and tensile strength. This point has been raised by some design engineers. Thus, the effect of using the actual cross-sectional area of GFRP bar in determining its properties on the design of FRP-RC sections, if any, is investigated thorough a simple design example explained herein as follows: Assume using a sand-coated GFRP bar of size No. 15. The bar was tested in tension and the specified tensile strength was 1184 MPa and the corresponding modulus of elasticity was 62.60 GPa. These values were determined based on a nominal cross-sectional area of 199 mm2 (15.9 mm-diameter). Assume that the properties are to be determined considering an actual cross-sectional area of 235 mm2 (17.3 mm-diameter). The specified tensile strength and the corresponding modulus of elasticity become 1003 MPa and 51.03 GPa, respectively. Those two different properties were used to design the same section (1000 mm×200 mm) according to CAN/CSA S6S1-10 to resist a service moment of 30.28 kN.m and ultimate factored moment of 55.43 kN.m. The design was made using a concrete strength of 35 MPa and assuming a concrete cover of 38 mm. Table 5 provides a comparison between the design summaries of both cases (Case 1 using the nominal cross-sectional area and Case 2 using the actual crosssectional area). The comparison in Table 4 indicates that there is no significant difference when the section is designed considering the nominal and the actual cross-sectional areas. This is due to the constant axial stiffness in both cases (EFRP1×AFRP1=EFRP2×AFRP2). The very slight difference is related to the small variation in the effective depth. Table 5: Design summary using nominal and actual cross-sectional areas Case 1- Nominal area Case 1- Actual area Design – Case 1: Nominal area Design – Case 2: Actual area (199 m2) (235 m2) fFRPu EFRP fFRPu EFRP Mr Strain at wcr Mr Strain at wcr (MPa) (GPa) (MPa) (GPa) (kN.m) service (µɛ) (mm) (kN.m) service (µɛ) (mm) 11084 62.6 1003 51.3 81.37 2528 0.49 80.82 2538 0.49
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6. EFFECT OF BAR SPACING The verification of the crack width at service load level (Clause 16.8.2.3) includes the spacing between the reinforcing bars. To the effect of the spacing between the GFRP bars was investigated through the design of 1000 mm×200 mm concrete section according to CAN/CSA S6S1-10 to resist a service moment of 30.28 kN.m and ultimate factored moment of 55.43 kN.m using GFRP bars of size No. 15 and size No. 20 having the same properties. These GFRP bar had a specified tensile strength of 1184 MPa and a corresponding modulus of elasticity was 62.60 GPa. The design using size No. 15 yielded GFRP bars spaced at 150 mm. The design was governed by the 0.5 mm crack width limit (serviceability). On the other hand, the design using No. 20 yielded GFRP bars spaced at 178 mm. The reinforcement amount in both cases was 1325mm2/m and 1600 mm2/m for the size No. 15 and size No. 20, respectively. Increasing the bar size from No. 15 to No. 20 (with the same properties) necessitated increasing the reinforcement amount by 21% to satisfy the crack with limit (0.5 mm). Thus, it is recommended to use small diameter bars at closer spacing rather than big diameter bars at larger spacing, assuming the properties of the bars are the same. It should be mentioned the minimum bar size that can be used is No. 15. 7. CONCLUSIONS Based on the previous analysis and discussion concerning the design of bridge deck slabs and cantilever overhangs using different types of GFRP reinforcing bars (EFRP=42.5, 52.5, and 62.6 GPa) and a concrete strength of 35 MPa according to the Canadian Highway Bridge Design Code CAN/CSA S6S1-10 (2010), the following conclusions can be drawn: 1. In the empirical method, increasing the slab thickness increased the required reinforcement in all direction, while increasing the elastic modulus, EFRP, decreased the bottom transverse reinforcement. 2. For deck slabs with 175 mm thickness, the empirical method yielded lower reinforcement amount than the flexural method for the four considered deck slabs. On contrary for deck slabs with 225 mm thickness, the empirical method yielded higher reinforcement amount than the flexural method for the four considered deck slabs. 3. For deck slabs with a thickness of 200 mm and effective girder spacing Se=2.0 to 2.5 m there was a good agreement between the amount of the transverse GFRP reinforcement calculated using the empirical and flexural design methods. 4. The design of deck slabs using the flexural method was governed in most cases by the crack width limit. Thus, increasing the elastic modulus of the GFRP reinforcement, EFRP, decreased the required GFRP reinforcement amount. Increasing the modulus of elasticity from Grade I to Grade III can save up to 20% of the reinforcement, considering the deck slabs tested herein. 5. The use of GFRP bars of Grade III in the cantilever overhangs reduced the required GFRP reinforcement amount by 33, 28, and 22% for thicknesses of 175, 200, and 225 mm, respectively, compared to GFRP bars of Grade I. 6. There is no significant difference when the section is designed considering the nominal and the actual crosssectional areas. This is due to the constant axial stiffness in both cases (EFRP1×AFRP1=EFRP2×AFRP2). The very slight difference may be related to the small variation in the effective depth. 7. It is recommended to use small diameter bars at closer spacing rather than big diameter bars at larger spacing, assuming the properties of the bars are the same, to control the crack width. It should be mentioned the minimum bar size that can be used is No. 15. 8. Based on this investigation, design charts could be easily prepared and introduced which can facilitate the design of such structural elements. Moreover, a complete study can be conducted to evaluate the exact cost of the different systems and the cost-effective system can be employed (i.e. for Se=3.00 m, it may be recommended to use GFRP of Grade III and concrete strength of 35 MPa with 200 mm thickness for the bridge deck slabs). 8. ACKNOWELGEMENT The authors wish to express their gratitude and sincere appreciation to the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Network of Centers of Excellence on Intelligent Sensing for Innovative Structures (ISIS Canada) and Fonds québécois de la recherche sur la nature et les technologies (FQRNT).
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9. REFERENCES ACI Committee 440. 2006. Specification for carbon and glass fiber-reinforced polymer bar materials for concrete reinforcement. ACI 440.6M, American Concrete Institute, Farmington Hills, USA, 6p. Ahmed, E. and Benmokrane, B. 2010. Design of concrete bridge deck slabs reinforced with GFRP bars according to the CHBDC S6-06. Proceedings of the 8th International Conference on Short and Medium Span Bridges (SMSB), Niagara Falls, Ontario, Canada, August 3-6, pp. 166.1-166.10. Ahmed, E., Settecasi, F., and Benmokrane, B. 2014. Construction and testing of GFRP-steel hybrid-reinforced concrete bridge-deck slabs of Sainte-Catherine overpass bridges. ASCE Journal of Bridge Engineering, 10.1061/(ASCE)BE.1943-5592.0000581 , 04014011. Benmokrane, B., El-Salakawy, E. F., El-Ragaby, A., and Lackey, T. 2006. Designing and testing of concrete bridge decks reinforced with glass FRP bars. ASCE Journal of Bridge Engineering, 11(2): 217-229. Benmokrane, B., El-Salakawy, E., El-Gamal, S. E., and Goulet, S. 2007. Construction and testing of Canada’s first concrete bridge deck totally reinforced with glass FRP bars: Val-Alain bridge on highway 20 east. ASCE Journal of Bridge Engineering, 12(5): 632–645. Canadian Standard Association (CSA). 2010. Canadian highway bridge design code. CAN/CSA S6S1-10, Rexdale, Ontario, Canada. Canadian Standard Association (CSA). 2010. Specification for fibre-reinforced polymers. CAN/CSA S807-10, Rexdale, Ontario, Canada, 27 p. Canadian Standard Association (CSA). 2012. Design and construction of building structures with fibre-reinforced polymers. CAN/CSA S806-12, Addendum, Rexdale, Ontario, Canada. Drouin, B., Latour, G., Mohamed, H.M. 2011. More than 10 years of field applications of FRP bars in Canada. Proceedings of the 4th International Conference on Durability & Sustainability of Fibre Reinforced Polymer (FRP) Composites for Construction and Rehabilitation of Structures (CDCC2011), July 20-22, Quebec City, Quebec, Canada, Eds.: Benmokrane, B., El-Salakawy, E., and Ahmed, E., pp. 345-356. Ghali, E., Sastri, V.S., Elboujdaini, M. 2007. Corrosion prevention and protection: practical solutions. John Wiley & Sons, UK, 557 p. Koch, G.H., Payer, J.H., Brongers, M.P.H., Thompson, N.G., Virmani, Y.P. 2002. Corrosion costs and preventive strategies in the United States. Report FHWA-RD-01-156, 786 p. Transportation for America. 2013. The Fix We’re In For: The State of Our Nation’s Bridges 2013. Transportation for America, Washington, USA, 8 p.
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