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Arabian Journal for Science and Engineering

, Volume 37, Issue 2, pp 489–504 | Cite as

Numerical Analysis of Thermal Behavior of Concrete Cover Around FRP-Bars in Cold Region

  • Ali ZaidiEmail author
  • Radhouane Masmoudi
Research Article - Civil Engineering

Abstract

The coefficient of thermal expansion of fiber reinforced polymer (FRP) in transverse direction is 3–8 times greater than that of hardened concrete. This thermal incompatibility between FRP bar and concrete in transverse direction may cause circumferential cracks within concrete at FRP bar/concrete interface under low temperatures and eventually the debonding of FRP bar from concrete. This paper presents numerical analysis using ADINA finite element software to investigate the thermal behavior of concrete cylinders reinforced with glass FRP bar (GFRP) in cold regions. The non-linear numerical results show that the first circumferential cracks occur within concrete at FRP bar/concrete interface at thermal loads ΔT cr varied between −35 and −25°C for GFRP bar-reinforced concrete cylinders having a ratio of concrete cover thickness to FRP bar diameter (c/d b) varied from 0.8 to 3.6 and a concrete tensile strength of 4.1 MPa. The numerical radial tensile stresses in concrete at the interface compared with those predicted from the analytical model are similar until the appearance of the circumferential cracks in concrete whose analytical results are greater. The ratio c/d b has no significant effect on the transverse thermal strains at FRP bar/concrete interface and also at external surface of concrete cover for a ratio of c/d b ≥ 1.5. Also, the transverse thermal strains, at external surface of concrete cover, predicted from non-linear numerical model are in good agreement with those obtained from the linear analytical model and experimental tests.

Keywords

Bars Concrete cover Fiber reinforced polymers Low temperatures Thermal stresses Thermal strains 

List of Symbols

a

Radius of FRP bar

b

Radius of concrete cylinder

c

Concrete cover thickness

db

Bar diameter

CTE

Coefficient of thermal expansion

Ec

Modulus of elasticity of concrete

El

Longitudinal modulus of elasticity of FRP bar

Et

Transverse modulus of elasticity of FRP bar

\({f^{\prime}_{{\rm c}28}}\)

Compressive strength of concrete

fct28

Tensile strength of concrete

ffu

Ultimate tensile strength of FRP bar

P

Radial pressure exerted by surrounding concrete on FRP bar

r

Ratio of radius of cylinder to that of FRP bar rb/a

αc

Coefficient of thermal expansion of concrete

αl

Longitudinal coefficient of thermal expansion of FRP bar

αt

Transverse coefficient of thermal expansion of FRP bar

ΔT

Temperature variation (thermal load)

ΔTcr

Thermal load producing the first circumferential cracks in concrete at FRP bar/concrete interface

\({\varepsilon_{{\rm ct}}}\)

Circumferential strains in concrete

\({\varepsilon_{{\rm ft}}}\)

Circumferential strains in FRP bar

νc

Poisson’s ratio of concrete

νtt

Transverse Poisson’s ratio of FRP bar

νlt

Longitudinal Poisson’s ratio of FRP bar

σρ

Radial tensile stress

σt

Circumferential compressive stress

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Copyright information

© King Fahd University of Petroleum and Minerals 2012

Authors and Affiliations

  1. 1.Laboratory of Civil EngineeringUniversity of LaghouatLaghouatAlgeria
  2. 2.Department of Civil EngineeringUniversity of SherbrookeSherbrookeCanada

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