Constituent Materials and Properties - Strengthening Design of Reinforced Concrete with FRP - page 69

Average
Thickness
(in.)

Average
Thickness
(mm)

Rupture
Load
(kips)

Rupture
Load
(kN)

Ultimate
Strain
( με )

Width
(in.)

Width
(mm) Specimen

CFRP-1 2.00 50.8 0.0279 0.709 6.13 27.28 12,514

CFRP-2 2.00 50.8 0.0285 0.724 6.14 27.32 14,123

CFRP-3 2.00 50.8 0.0276 0.701 6.16 27.41 12,931

CFRP-4 2.00 50.8 0.0273 0.693 6.18 27.50 11,947

CFRP-5 2.00 50.8 0.0265 0.673 6.04 26.88 12,993

Average 2.00 50.8 0.0276 0.700 6.13 27.28 12,902

Problem 3.4
Using the density values in Table 3.15, determine the ratio of the tensile strength to
density and tensile modulus to density per inch thickness (per mm thickness) and
rank the four materials based on the two ratios from highest to lowest. Use Table 3.7
for GFRP, Table 3.9 for CFRP, and Table 3.12 for AFRP. Assume the tensile strength
and modulus of steel to be 70 ksi and 29,000 ksi (483 MPa and 200 GPa), respectively.

Problem 3.5
Determine the angle-ply orientation needed to make the following FRP materials
thermally compatible with concrete in the longitudinal direction.

a. GFRP

b. CFRP

c. AFRP

Take the average α 1 and α 2 for each from Table 3.16 and take α concrete = 5.5 × 10 −6 /°F.
Indicate which composite of the three is the most thermally compatible with rein-
forced concrete in the longitudinal direction when used as a 0° unidirectional ply.

Problem 3.6
Design a ±θ angle-ply laminate for each FRP composite indicated in Problems 3.5
to be thermally compatible with concrete in the transverse direction to limit the pos-
sibility of matrix cracking.

REFERENCES
ACI 440R-07. 2007. Report on fiber-reinforced polymer (FRP) reinforcement for concrete
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ACI 440.2R-08. 2008. Guide for the design and construction of externally bonded FRP sys-
tems for strengthening concrete structures. ACI Committee 440, Farmington Hills, MI.
Alkhrdaji, T., A. Nanni, and R. Mayo. 2000. Upgrading Missouri transportation infrastructure: Solid
RC decks strengthened with FRP systems. Transportation Research Record , no. 1740:157-69.
Arduini, M., A. Tommaso, and A. Nanni. 1997. Brittle failure in FRP plate and sheet bonded
beams. ACI Structural Journal 94 (4): 363-70.
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Beer, F. P., and E. R. Johnston Jr. 1992. Mechanics of materials . 2nd ed. New York: McGraw-Hill.
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