Experimental Mechanics

, Volume 45, Issue 1, pp 35–41 | Cite as

Prediction of bond failure and deflection of carbon fiber-reinforced plastic reinforced concrete beams

  • A. Maji
  • A. L. Orozco
Article
Received:

Abstract

Carbon fiber-reinforced plastic (CFRP) reinforced concrete beams can fail due to interface debonding, due to the high tensile strength of such rebars. A set of 16 concrete beams reinforced with different amounts of CFRP reinforcement was subject to static three-point bending. The beam dimensions and CFRP reinforcements used were selected to demonstrate a transition from compression failure to bond failure with decreasing reinforcement ratio. It is shown that accurate bond strength data to predict such failures can be obtained from a “hinged-beam” test configuration, rather than the conventional direct “pull-out” tests. Deflection under service loads can also be predicted more accurately using a proposed equation that includes the reinforcement ratio and the elastic modulus of the reinforcement.

Key Words

Bond slip deflections pull-out failure strength 

Nomenclature

f'c

concrete strength in compression

Ef

E lb =E FRP =modulus of elasticity of the FRP

ρf

ratio of tension reinforcement=A f /bd

AFRP

A f =area of the FRP tension reinforcement

b

width of the member

d

distance from extreme compression fiber to centroid of tension reinforcement

α1

ratio of the depth of the equivalent rectangular stress block to the depth to the neutral axis at ε cu

ffd

0.65f fu

cb

ε cu d/(ε cu +ε fd )

εcu

maximum concrete strain in compression

εfd

rebar strain=f fd /E f

db

diameter of the rebar

Ab

cross-sectional area of the rebar

C

constant=πd b /E lb A b

x

distance along the bar starting at the free end of the beam

εb(x)

rebar strain variation along the distancex

N(x)

normal force along the bar

k

constant that multiplied by the effective depth of the section gives the neutral axis position from the compression

fiber

\(\sqrt {(\rho n)^2 + 2(\rho n) - } (\rho n)\)

Icr

cracked moment of inertia of a cross section=(kd) 3 (b)/3+nA FRP (d−kd) 2

Ec

modulus of elasticity of the concrete

n

modulus ratio=E FRP /E c

Ig

gross moment of inertia

fr

modulus of rupture of the concrete

Mcr

cracking moment=f r (I tr )/y t

Itr

moment of inertia of the transformed section

yt

distance from centroidal axis to the extreme fiber in tension

Ie

effective moment of inertia

Ma

maximum moment in a member at the stage for which deflection is computed

α

0.84

β

7.0

γ

reduction factor=E FRP /E s

ŋ

100 π−0.2

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Copyright information

© Society for Experimental Mechanics 2005

Authors and Affiliations

  • A. Maji
    • 1
  • A. L. Orozco
    • 2
  1. 1.Department of Civil EngineeringUniversity of New MexicoAlbuquerqueUSA
  2. 2.Facultad de IngenieriaUniversidad Autonoma de ChihuahuaChihuahuaMexico

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