Structural applications with Ultra High Performance Fibre Reinforced Concretes (UHPFRC) have been emerging worldwide thanks to the outstanding tensile strength and ductility of this category of advanced cement based materials. From a design point of view, a critical aspect is to guarantee the ductility of the structural response associated to local material non-brittleness, which strongly depends on the fibre dispersion and orientation. This work aims at considering the effect of fibre orientation on the behaviour of UHPFRC slab for composite bridges. Several square slabs made of UHPFRC were cast by changing the concrete flow direction and the position of internal cold joints, in order to document the structural consequences of defects in the casting process.. The slabs were tested under biaxial bending under hyperstatic conditions. For four of these slabs, featuring different casting methods in order to induce different, even “defective” dispersion of fibres, a non-destructive magnetic method was employed to provide a complete survey of local dispersion and orientation of the fibres. The damage process, with emphasis on the micro-crack formation and the crack opening, was measured by 3D digital image correlation. The on-going cracking and failure modes were hence analysed in view of the guessed dispersion and orientation of fibres, highlighting the important effect of fibre orientation on the ductility of UHPFRC slabs and the ability of combining magnetic methods and DIC analyses to capture those effects.
Flow induced alignment of fibres in HPFRCC slabs: non-destructive magnetic survey and correlation with failure modes
FERRARA, LIBERATO;FAIFER, MARCO;
2016-01-01
Abstract
Structural applications with Ultra High Performance Fibre Reinforced Concretes (UHPFRC) have been emerging worldwide thanks to the outstanding tensile strength and ductility of this category of advanced cement based materials. From a design point of view, a critical aspect is to guarantee the ductility of the structural response associated to local material non-brittleness, which strongly depends on the fibre dispersion and orientation. This work aims at considering the effect of fibre orientation on the behaviour of UHPFRC slab for composite bridges. Several square slabs made of UHPFRC were cast by changing the concrete flow direction and the position of internal cold joints, in order to document the structural consequences of defects in the casting process.. The slabs were tested under biaxial bending under hyperstatic conditions. For four of these slabs, featuring different casting methods in order to induce different, even “defective” dispersion of fibres, a non-destructive magnetic method was employed to provide a complete survey of local dispersion and orientation of the fibres. The damage process, with emphasis on the micro-crack formation and the crack opening, was measured by 3D digital image correlation. The on-going cracking and failure modes were hence analysed in view of the guessed dispersion and orientation of fibres, highlighting the important effect of fibre orientation on the ductility of UHPFRC slabs and the ability of combining magnetic methods and DIC analyses to capture those effects.File | Dimensione | Formato | |
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BEFIB-2016-Ferrara et al paper 186.pdf
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