Mahsa Taheri

Parametric Study of the Use of Strain Softening/Hardening FRC for RC Elements Failing in Bending

Using a design-oriented model recently developed for prediction of the moment-curvature relationship of a cross section of beams made by strain-softening or strain-hardening fiber reinforced concrete (FRC) and that can also include a certain percentage of longitudinal steel bars, a parametric study is carried out to evidence the effect of relevant characteristics of the post-cracking behavior of these materials in the moment-curvature and force-deflection responses of this type of structural elements. The study also analyzes the influence of the reinforcement ratio of longitudinal steel bars, ρ, in order to show that for a certain content of fibers the benefits of fiber reinforcement, mainly at serviceability limit state conditions, decrease with the increase of ρ. Adopting the formulation of the CEB-FIB final draft Model Code, the moment-crack width relationship of FRC beams reinforced with steel bars are obtained and the predictive performance of this approach is assessed by comparing analytical and exp...

Steel fibre reinforced concrete for elements failing in bending and in shear

Discrete steel fibres can increase significantly the bending and the shear resistance of concrete structural elements when Steel Fibre Reinforced Concrete (SFRC) is designed in such a way that fibre reinforcing mechanisms are optimized. To assess the fibre reinforcement effectiveness in shallow structural elements failing in bending and in shear, experimental and numerical research were performed. Uniaxial compression and bending tests were executed to derive the constitutive laws of the developed SFRC. Using a cross-section layered model and the material constitutive laws, the deformational behaviour of structural elements failing in bending was predicted from the moment-curvature relationship of the representative cross sections. To evaluate the influence of the percentage of fibres on the shear resistance of shallow structures, three point bending tests with shallow beams were performed. The applicability of the formulation proposed by RILEM TC 162-TDF for the prediction of the shear resistance of SFRC elements was evaluated. Inverse analysis was adopted to determine indirectly the values of the fracture mode I parameters of the developed SFRC. With these values, and using a softening diagram for modelling the crack shear softening behaviour, the response of the SFRC beams failing in shear was predicted.

RETRACTED ARTICLE: Steel fibre reinforced concrete for elements failing in bending and in shear

Discrete steel fibres can increase significantly the bending and the shear resistance of concrete structural elements when Steel Fibre Reinforced Concrete (SFRC) is designed in such a way that fibre reinforcing mechanisms are optimized. To assess the fibre reinforcement effectiveness in shallow structural elements failing in bending and in shear, experimental and numerical research were performed. Uniaxial compression and bending tests were executed to derive the constitutive laws of the developed SFRC. Using a cross-section layered model and the material constitutive laws, the deformational behaviour of structural elements failing in bending was predicted from the moment-curvature relationship of the representative cross sections. To evaluate the influence of the percentage of fibres on the shear resistance of shallow structures, three point bending tests with shallow beams were performed. The applicability of the formulation proposed by RILEM TC 162-TDF for the prediction of the shear resistance of SFRC elements was evaluated. Inverse analysis was adopted to determine indirectly the values of the fracture mode I parameters of the developed SFRC. With these values, and using a softening diagram for modelling the crack shear softening behaviour, the response of the SFRC beams failing in shear was predicted.