Magnetic orientation of steel fibres in self-compacting concrete beams: Effect on failure behaviour

Wijffels, Mjh Mark; Wolfs, Rob; Suiker, A.S.J.; Salet, Tam Theo

doi:10.1016/j.cemconcomp.2017.04.005

Cited by 58 publications

(12 citation statements)

References 9 publications

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“…Several studies found an increase of resistance up to 20% for inclination angles of up to 60° (Van Gysel 2000;Robins, Austin, and Jones 2002), whereas another work found an important decrease of resistance leading up to 50% at 60° (Bartos and Duris 1994). Yet, others noted that the post-fracture resistance and energy absorption significantly reduces for inclination angles over 30° (Banthia and Trottier 1994;Armelin and Banthia 1997;Svec et al 2012), supported by a study on the effect of the magnetic orientation of fibers (Wijffels et al 2017). When corrected for a fixed limited value of fiber slip, several studies indicate an optimal pull-out resistance is reached at inclination angles of 10-15° (Markovic 2006).…”

Section: Structural Performance Of Concrete Reinforced With Straight Steel Fibersmentioning

confidence: 96%

Ductility of 3D printed concrete reinforced with short straight steel fibers

Bos

Bosco

Salet

2018

Virtual and Physical Prototyping

140

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With the number of 3D printed concrete structures rapidly increasing, the demand for concepts that allow for robust and ductile printed objects becomes increasingly pressing. An obvious solution strategy is the inclusion of fibers in the printed material. In this study, the effect of adding short straight steel fibers on the failure behaviour of Weber 3D 115-1 print mortar has been studied through several CMOD tests on cast and printed concrete, on different scales. The experiments have also been simulated numerically. The research has shown that the fibers cause an important increase in flexural strength, and eliminate the strength difference between cast and printed concrete that exists without fibers. The post-peak behaviour, nevertheless, has to be characterised as strongly strain-softening. In the printed specimens, a strong fiber orientation in the direction of the filament occurs. However, this has no notable effect on the performance in the tested direction: cast and printed concrete with fibers behave similarly in the CMOD test. For the key parameters, no scale effect was found for the specimens with fibers, contrary to the ones without. Numerical modelling of the test by using the Concrete Damage Plasticity material model of Abaqus, with a Thorenfeldt-based constitutive law in compression and a customised constitutive law in tension, results in a reasonable fit with the experimental results.

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Section: Structural Performance Of Concrete Reinforced With Straight Steel Fibersmentioning

confidence: 96%

Ductility of 3D printed concrete reinforced with short straight steel fibers

Bos

Bosco

Salet

2018

Virtual and Physical Prototyping

140

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“…In case the concrete printing material is reinforced by fibres, the microstructural stiffening effect by the fibres should be accounted for in the calibration of Eq. 4, although the influence may be negligible for low fibre volume percentages [32].…”

Section: Elastic Bucklingmentioning

confidence: 99%

Structural failure during extrusion-based 3D printing processes

Wolfs

Suiker

2019

Int J Adv Manuf Technol

145

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This contribution studies failure by elastic buckling and plastic collapse of wall structures during extrusion-based 3D printing processes. Results obtained from the parametric 3D printing model recently developed by Suiker (Int J Mech Sci, 137: 145-170, 2018), among which closed-form expressions useful for engineering practice, are validated against results of dedicated FEM simulations and 3D concrete printing experiments. In the comparison with the FEM simulations, various types of wall structures are considered, which are subjected to linear and exponentially decaying curing processes at different curing rates. For almost all cases considered, the critical wall buckling length computed by the parametric model turns out to be in excellent agreement with the result from the FEM simulations. Some differences may occur for the particular case of a straight wall clamped along its vertical edges and subjected to a relatively high curing rate, which can be ascribed to the approximate form of the horizontal buckling shape used in the parametric model. The buckling responses computed by the two models for a wall structure with imperfections of different wavelengths under increasing deflection correctly approaches the corresponding bifurcation buckling length. Further, under a specific change of the material properties, the parametric model and the FEM model predict a similar transition in failure mechanism, from elastic buckling to plastic collapse. The experimental validation of the parametric model is directed towards walls manufactured by 3D concrete printing, whereby the effect of the material curing rate on the failure behaviour of the wall is explored by studying walls of various widths. At a relatively low curing rate, the experimental buckling load is well described when the parametric model uses a linear curing function. However, the experimental results suggest the extension of the linear curing function with a quadratic term if the curing process under a relatively long printing time is accelerated by thermal heating of the 3D printing facility. In conclusion, the present validation study confirms that the parametric model provides a useful research and design tool for the prediction of structural failure during extrusion-based 3D printing. The model can be applied to quickly and systematically explore the influence of the individual printing process parameters on the failure response of 3D-printed walls, which can be translated to directives regarding the optimisation of material usage and printing time.

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“…The orientation of the fibres can affect the impact resistance of the composite [ 83 , 84 , 85 ]. All FTSFC specimens had a planar orientation of fibres in the majority of cases.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Modified Falling Mass Impact Test Performance on Functionally Graded Two Stage Aggregate Fibrous Concrete

2021

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This research examined the performance of functionally graded two-stage fibrous concrete (FTSFC) against modified repeated falling-mass impacts. This study led to the concept of creating improved multiphysics model of fibre composites with better impact resistance for potential protective constructions. FTSFC was developed based on the bio-inspiring strength of turtle shells. The excellent impact resistance of FTSFC was accomplished by including a larger quantity of steel and polypropylene fibres in the outer layers. At the same time, one- and two-layered concrete were cast and compared to evaluate the efficiency of three-layered FTSFC. To minimize the dispersed test results, a modified form of the 544 drop-mass impact test was recommended by the American Concrete Institute (ACI). The modification was a knife-edge notched specimen instead of a solid cylindrical specimen without a notch. This modification predefined a crack path and reduced the dispersion of results. Cracking and failure impact numbers, ductility index, and failure mode were the testing criteria. The suggested modification to the ACI impact test decreased the coefficient of variance, showing that the dispersion of test results was reduced significantly. This study led to the concept of creating improved, fibre composites with better impact resistance for potential protective constructions.

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Magnetic orientation of steel fibres in self-compacting concrete beams: Effect on failure behaviour

Cited by 58 publications

References 9 publications

Ductility of 3D printed concrete reinforced with short straight steel fibers

Ductility of 3D printed concrete reinforced with short straight steel fibers

Structural failure during extrusion-based 3D printing processes

Modified Falling Mass Impact Test Performance on Functionally Graded Two Stage Aggregate Fibrous Concrete

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