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Materials and Structures

, Volume 45, Issue 4, pp 623–636 | Cite as

Design of SFRC structural elements: flexural behaviour prediction

  • Renaud de Montaignac
  • Bruno Massicotte
  • Jean-Philippe Charron
Original Article

Abstract

Practical steel fibre reinforced concrete (SFRC) applications in load-carrying structural members have yet to gain wide acceptance in design codes. This is partly explained by the lack of a unified design philosophy adapted to this material. A model based on simple and widely accepted assumptions is proposed for the analysis and the design of SFRC members subjected to bending moments. In order to evaluate the accuracy of the analytical model predictions, an extensive experimental program was conducted on 21 rectangular and T-beams of various sizes produced with five different types of SFRC. The contribution of fibres at different loading phases in bending is described in detail. The analytical model accuracy to predict maximum crack opening applicable in service conditions and at the ultimate flexural strength are compared to experimental measurements. Discrepancies observed are related to the dispersion of the material properties and the difference of fibre orientation in beams and characterization specimens. Finally, the proposed design approach is applied to the design of a realistic T-beam subjected to positive and negative bending moments.

Keywords

Steel fibre reinforced concrete Flexural behaviour Analytical model Characteristic length Fibre orientation Design 

List of symbols

Ec

Young modulus

H

Height of the specimen

L

Length between support

Lr

Reference length (geometric parameter)

M

Bending moment

MEXP

Experimental bending moment

MMOD

Model bending moment

N

Normal force

Na

Normal load

Nc

Compression normal force

Nf

Tensile normal force due to FRC

Ns

Tensile normal force due to conventional steel reinforcement

Nt

Tensile normal force due elastic behaviour of concrete

P

Load

w

Crack width

wmax

Maximum crack opening for design

y

Distance between neutral axis and the extreme tensile side of the cross section

z

Crack depth

δ

Deflection

ε

Strain

εc

Strain at face in compression

εe

Elastic strain

εt

Strain at face in tension

εw

Strain equivalent to a crack opening

ϕs

Reinforcement strength reduction factor

ϕf

SFRC strength reduction factor

θ

Crack angle

γ

Reliability coefficient

ψ

Curvature

σ

Stress

σf

Post-cracking stress

Notes

Acknowledgments

This project has been financially supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Center for Research on Concrete Infrastructures of Quebec (FQRNT—CRIB). Materials were graciously provided by Bekaert, Holcim and Euclid.

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Copyright information

© RILEM 2011

Authors and Affiliations

  • Renaud de Montaignac
    • 1
  • Bruno Massicotte
    • 1
  • Jean-Philippe Charron
    • 1
  1. 1.Department of Civil, Geological and Mining EngineeringEcole Polytechnique of MontréalMontrealCanada

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