Abstract
Fibre-reinforced concrete (FRC) is a material that can be characterized by a high standard deviation in the post-peak tensile region. As consequence, structures made of FRC show a too safe prediction of the maximum bearing capacity when derived from characteristic values identified by means of small standard specimens. The Model Code 2010 has introduced a coefficient, named structural redistribution factor, that is able to take into account a reduced variability of the structural response when compared to that of material. A simplified procedure to provide an upper bound estimation of the structural redistribution factor based on the yield line method and able to take into account the material heterogeneity is presented. As case studies, a FRC full-scale elevated flat slab, a slab on ground and a full-scale beam are considered.
Similar content being viewed by others
Abbreviations
- CMOD:
-
Crack mouth opening displacement
- COD:
-
Crack opening displacement
- COV:
-
Coefficient of variation
- CTOD:
-
Crack tip opening displacement
- FRC:
-
Fibre reinforced concrete
- d f :
-
Fibre diameter
- E :
-
Young’s modulus
- f c :
-
Concrete compressive strength
- f eq1 :
-
Average flexural nominal strength in the CTOD range between 0 and 0.6 mm
- f eq2 :
-
Average flexural nominal strength in the CTOD range between 0.6 and 3 mm
- f R1 :
-
Residual flexural nominal strength of FRC corresponding to CMOD = 0.5 mm
- f R3 :
-
Residual flexural nominal strength of FRC corresponding to CMOD = 2.5 mm
- f Fts :
-
FRC serviceability uniaxial tensile residual strength
- f Ftu :
-
FRC ultimate uniaxial tensile residual strength
- f If :
-
Flexural nominal stress corresponding to a CTOD equal to 25 μm
- f L :
-
Limit of proportionality
- k :
-
Subgrade modulus
- K :
-
Fibre orientation factor
- K Rd :
-
Redistribution factor
- \(K_{{_{\text{Rd}} }}^{\text{MC}}\) :
-
Model Code definition of the redistribution factor
- K Rdj :
-
Alternative definitions of the redistribution factor proposed by [1] j = 1, 2, 3, 4
- l f :
-
Fibre length
- m :
-
Moment per unit width
- m u :
-
Ultimate moment per unit width
- P :
-
Load
- P cr :
-
Load at the elastic limit, first cracking load
- P max :
-
Maximum load
- P u :
-
Ultimate load
- \(P_{\text{eq}}^{\text{u}}\) :
-
Ultimate equivalent load
- q u :
-
Distributed load
- V :
-
Fractured volume at failure involved in a structure
- V 0 :
-
Fractured volume at failure involved in a classification test
- w u :
-
Maximum crack opening accepted in structural design
- W E :
-
External work
- W I :
-
Internal work
- α :
-
Percentile level
- β:
-
Factor to account fibre distribution over slab thickness
- δ :
-
Virtual displacement
- θ i :
-
Angle of rotation
- υ :
-
Poisson’s ratio
- Hom:
-
Homogeneous
- k :
-
Characteristic value, 0.05 percentile value
- m :
-
Mean value, 0.5 percentile value
- Rand:
-
Random; heterogeneous
- cr:
-
Cracking
- max:
-
Maximum
- u:
-
Ultimate
- α :
-
Percentile level
- ^:
-
Percentile estimate
References
di Prisco M, Martinelli P, Dozio D (2016) The structural redistribution coefficient KRd: a numerical approach to its evaluation. Struct Concr 17:390–407
Cominoli L (2007) Studio sul calcestruzzo fibrorinforzato per applicazioni industriali: dalle proprietà del materiale al comportamento strutturale. PhD thesis. Brescia, University of Brescia, (in Italian)
di Prisco M, Colombo M, Dozio D, Mauri M (2006) Pavimentazione industriale in SFRC: una realizzazione su solai alveolari. In Proceedings of 16 CTE Conference, Parma (in Italian)
di Prisco M, Plizzari G, Vandewalle L (2009) Fibre reinforced concrete: New design perspectives. Mater Struct 42:1261–1281
Fib Model Code for Concrete Structures 2010 (2013) Fédération Internationale du Béton, Ernst & Sohn, Lausanne
Cavalaro SHP, Aguado A (2015) Intrinsic scatter of FRC: an alternative philosophy to estimate characteristic values. Mater Struct 48:3537–3555
Pujadas P, Blanco A, Cavalaro S, Aguado A (2014) Plastic fibres as the only reinforcement for flat suspended slabs: Experimental investigation and numerical simulation. Constr Build Mater 57:92–104
Pujadas P, Blanco A, Cavalaro SHP, Aguado A, Grünewald S, Blom K, Walraven JC (2014) Plastic fibres as the only reinforcement for flat suspended slabs: parametric study and design considerations. Constr Build Mater 70:88–96
Salehian H, Barros JAO, Taheri M (2014) Evaluation of the influence of post-cracking response of steel fibre reinforced concrete (SFRC) on load carrying capacity of SFRC panels. Constr Build Mater 73:289–304
Johansen KW (1962) Yield-line theory. Cement and Concrete Association, London
CNR-DT 204 (2006) Guidelines for design, construction and production control of fiber reinforced concrete structures, National Research Council of Italy
DafStb Guideline (2014) Steel fibre reinforced concrete, German Committee for reinforced concrete
Kasper T, Stang H, Mjoernell P, Slot H, Vitt G, Thrane LN, Reimer L (2014) Design guideline for structural applications of steel fibre reinforced concrete, SFRC Consortium
Drucker DC (1961) On structural concrete and the theorems of limit analysis. Int Assoc Bridge Struct Eng Pub 21:49–59
Meyerhof GG (1962) Load carrying capacity of concrete pavements. ASCE J Soil Mech Found Div 88(3):89–115
di Prisco M, Ferrara L, Caverzan A (2012) Self-compacting fibre reinforced concrete: is the material really isotropic? In: 3rd Iberian Congress on self-compacting concrete, Madrid
EN 14651 (2004) Test method for metallic fiber concrete—Measuring the flexural tensile strength (limit of proportionality, residual)
UNI 11039 (2003) Steel fibre reinforced concrete—Part I: Definitions, classification specification and conformity. Part II: test method for measuring first crack strength and ductility indexes. Italian Board for Standardization
EN 1990 (2006) Eurocode—basis of structural design. European Committee for Standardization, Brussels
Lee TH, Mosalam KM (2004) Probabilistic fiber element modeling of reinforced concrete structures. Comput Struct 82:2285–2299
Hordijk D (1991) Local approach to fatigue of concrete. PhD Thesis. Delft, delft University of technology
Parmentier B, Van Itterbeeck, P, Skowron A (2014) The behaviour of SFRC flat slabs: the Limelette full-scale experiments for supporting design model codes. In: Charron JP, Massicotte B, Mobasher B, Plizzari G (eds) FRC 2014 Joint ACI-fib International Workshop—fibre reinforced concrete: from design to structural applications, Montreal
di Prisco M, Martinelli P, Parmentier B (2016) On the reliability of design approach for FRC structures according to Model Code 2010: the case of elevated slabs. Struct Concr. doi:10.1002/suco.201500151
di Prisco M, Ferrara L, Lamperti MGL (2013) Double edge wedge splitting (DEWS): An indirect tension test to identify post-cracking behaviour of fibre reinforced cementitious composites. Mater Struct 46:1893–1918
Sorelli L, Meda A, Plizzari GA (2006) Steel fiber concrete slabs on ground: a structural matter. ACI Struct J 103:551–558
Dozio D (2008) SFRC structures: identification of the uniaxial tension characteristic constitutive law. PhD Thesis. Milano, Politecnico di Milano
di Prisco M, Colombo M, Dozio D (2013) Fibre-reinforced concrete in fib Model Code 2010: principles, models and test validation. Struct Concr 14:342–361
Baumann RA, Weisgerber FE (1983) Yield-line analysis of slabs-on-grade. J Struct Eng ASCE 109:1553–1568
Meda A (2003) On the extension of the yield-line method to the design of SFRC slabs on grade. Stud Res 24:223–240
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Colombo, M., Martinelli, P. & di Prisco, M. On the evaluation of the structural redistribution factor in FRC design: a yield line approach. Mater Struct 50, 100 (2017). https://doi.org/10.1617/s11527-016-0969-3
Received:
Accepted:
Published:
DOI: https://doi.org/10.1617/s11527-016-0969-3