Pull-out behaviour of hooked steel fibres

A programme of research is described that has investigated the fracture of steel fibre reinforced sprayed concrete under flexural load, with the aim of developing a stress-profile model to predict flexural behaviour in the form of a load-deflection response. This paper reports the work associated with establishing the pull-out characteristics of hooked end fibres. The effects of matrix strength, fibre embedment length and orientation are described, together with the interaction of these parameters. The relationships established can be used to model the tensile response of a beam at varying crack width and hence form a key part of the stress-profile for predicting residual flexural strength, which is an essential requirement of a much needed design rationale for steel fibre concrete.RésuméLe programme de recherche décrit porte sur la rupture du béton projeté renforcé de fibres d'acier sous charge en flexion. Il a pour objectif de développer un modèle de profil de contrainte capable de prévoir le comportement en flexion sous la forme d'une réponse charge-déflexion. Cet article présente un travail lié à l'établissement des caractéristiques d'arrachement de fibres aux extrémités crochetées. Les effets de la résistance de la matrice, de la longueur d'enfoncement et l'orientation des fibres sont décrits, ainsi que l'interaction de ces paramètres. Les relations établies peuvent être utilisées pour modéliser la réponse en tension d'une poutre à une largeur de fissuration variable, et donc pour former la majeure partie du profil de contrainte visant à prévoir la résistance à la flexion résiduelle, qui est l'une des exigences essentielles d'une argumentation très attendue sur l'étude des bétons renforcés de fibres.

[1]  P.J.M. Bartos,et al.  Inclined tensile strength of steel fibres in a cement-based composite , 1994 .

[2]  B. P. Hughes,et al.  Fibre bond strengths in cement and concrete , 1975 .

[3]  Surendra P. Shah,et al.  Fiber-Reinforced Cement Composites , 1992 .

[4]  P. Bartos,et al.  Review paper: Bond in fibre reinforced cements and concretes , 1981 .

[5]  Luigi Nicolais,et al.  Analysis of steel fibre pull-out from a cement matrix using video photography , 1996 .

[6]  Lucie Vandewalle,et al.  RILEM TC162-TDF : Test and Design Methods for Steel Fibre Reinforced Concrete : Bending Test, "Technical Recommendation" , 2002 .

[7]  M. Maage,et al.  Interaction between steel fibers and cement based matrixes , 1977 .

[8]  Antoine E. Naaman,et al.  Bond-Slip Mechanisms of Steel Fibers in Concrete , 1991 .

[9]  Simon A. Austin,et al.  Flexural strain and crack width measurement of steel-fibre-reinforced concrete by optical grid and electrical gauge methods , 2001 .

[10]  Mohamed Maalej,et al.  Toughening in cement based composites. Part I: Cement, mortar, and concrete , 1996 .

[11]  Mohamed Maalej,et al.  Toughening in cement based composites. Part II: Fiber reinforced cementitious composites , 1996 .

[12]  Samir Said,et al.  Studies of the Properties of the Fiber-Matrix Interface in Steel fiber Reinforced Mortar , 1987 .

[13]  Antoine E. Naaman,et al.  Pull-Out Mechanism in Steel Fiber-Reinforced Concrete , 1976 .

[14]  Nemkumar Banthia,et al.  A study of some factors affecting the fiber–matrix bond in steel fiber reinforced concrete , 1990 .

[15]  Nemkumar Banthia,et al.  Concrete Reinforced with Deformed Steel Fibers, Part I: Bond-Slip Mechanisms , 1994 .

[16]  Lucie Vandewalle,et al.  RILEM TC 162-TDF: Test and design methods for steel fibre reinforced concrete' - sigma-epsilon-design method - Final Recommendation , 2003 .