Application of FRC constitutive models to modelling of slabs

Abstract

Fibre reinforcement technology has advanced significantly in recent years and, as a result, expanded into different applications. In particular, steel fibre-reinforced concrete has been successfully employed in flat slabs of several buildings in Europe with fibres as the only reinforcement. However, design methods for fibre-reinforced concrete (FRC) structures do not consider differences that may result from material characterisation tests that are not representative of the structural behaviour and fibre orientation of real-scale elements. In this regard, this paper presents a numerical study in which two constitutive models for FRC based on the bending test are applied to estimate the flexural behaviour of full-scale slabs of different dimensions. Likewise, a parametric study is conducted to analyse how the parameters of these constitutive models affect the flexural response of the slabs, and a numerical fit of the experimental data is performed. Finite element simulations using the constitutive models overestimate the experimental results. The parametric study also reveals that the parameter r2 (stress after cracking) has a particularly importance influence on the response. Furthermore, enhanced sectional behaviour of the slabs was observed as their width was increased.Peer ReviewedPostprint (published version

Influence of the Type of Fiber on the Structural Response and Design of FRC Slabs

“…First of all, assuming an isotropic fiber orientation by considering an orientation factor equal to 1.0 is not suitable for the slabs tested, despite being common practice in the design. This was already reported by Blanco et al (2015b) and by Pujadas et al (2014a) for the case of the RILEM (RILEM 2003) and the Spanish recommendations (CPH 2008). Moreover, the flexural response of the small beam used in the characterization test is not representative of the structural behavior of slabs.…”

“…Symmetry of the slabs was assumed in order to reduce the number of elements and the calculation time. Previous studies demonstrated that modeling a quarter of the slabs yields almost identical results to the ones obtained with the simulation of the whole slab (Blanco et al 2015b). The neoprene sheets located in the load application point and in the supports were also modeled to assure a realistic representation of the boundary conditions.…”

Assessment of the fibre orientation factor in SFRC slabs

“…Since the fibres tend to align perpendicularly to the cast direction and in the same plane of the concrete flow, the number of fibres crossing the failure plane increases. In line with that, a recent study by Blanco et al [7] revealed an enhanced sectional response in this type of element as the width increases.…”

“…The preliminary analysis showed that the P-d curves for the complete slab and for the quarter of the slab are practically identical. Based on such outcome [7], the reduced model was selected.…”

Diseño óptimo de dovelas de hormigón reforzado con fibras para el revestimiento de túneles

“…Este aspecto ya ha sido probado a nivel experimental en dovelas [41] y losas [42][43][44] y cuantificado de forma cualitativa por [43][44][45][46]; asimismo, en [47,48] se han llevado a cabo simulaciones numéricas del comportamiento mecánico en losas de HRF, empleando distintas ecuaciones constitutivas, con el fin de poder calibrar dicho coeficiente. Sin embargo, pese a los avances en esta dirección, aún no se ha podido establecer un método sistemático y fiable para poder evaluar el coeficiente K para los distintos HRF y distintas condiciones de contorno.…”