Prediction of fracture parameters and strain-softening behavior of concrete: effect of frost action

This paper investigates crack speed in ultra-high performance concrete (UHPC) using pre-notched three-point bending specimens. The experimental parameters are fiber volume fraction and rate of loading. A hydraulic servo-controlled testing machine is used to apply lower notch tip strain rates, in the range of 0.025 to 1.0 1/s, while a newly developed impact testing system is used to achieve higher notch tip strain rates, ranging from 6.8 to 41.1 1/s. A high-speed camera is used to record images of the UHPC specimens during testing. Notch tip strain and crack speed are computed from the images, which show that crack speed increases asymptotically as the crack initiation strain rate increases. Crack speeds of up to 514 m/s were achieved at the lower notch tip strain rates and up to 1454 m/s for the higher notch tip strain rates. The achieved relationships are incorporated into a recently proposed crack-velocity dependent dynamic fracture model. The model is validated using published experimental data and used to show that, like conventional concrete, the strain rate sensitivity of UHPC is strongly associated with the characteristics of dynamic crack growth.

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“…The critical stress intensity factor for a pre-notched three-point bending specimen is calculated using Eq. (1) [29,30]:…”

Section: Critical Stress Intensity Factormentioning

confidence: 99%

Crack propagation speed in ultra high performance concrete (UHPC)

Pyo

Alkaysi

El‐Tawil

2016

Construction and Building Materials

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“…Moreover, for concretes elaborated with recycled aggregates provided from construction and demolition waste, we establish that ( α E ) RA = 0.998 for Γ = 1 whatever the origin of recycled aggregates (Table ). The relation proposed in Wardeh et al estimates the tangent elastic modulus. The three models are represented in Figure a with 508 experimental values taken from this work and the literature including 195 values for RAC …”

Section: Mechanical Properties and Prediction Relationshipsmentioning

confidence: 91%

“…As can be seen, the peak load decreases by increasing the replacement ratio. In order to study the postpeak behavior the analytical model proposed by Wardeh and Ghorbel has been used.…”

Section: Fracture Behavior Of Racmentioning

confidence: 99%

Mechanical and fracture properties of recycled aggregate concrete in design codes and empirical models

Ghorbel

Wardeh

Fares

2019

Structural Concrete

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In this paper the relationships between the mechanical and fracture properties of recycled aggregate concretes (RAC) are investigated based on the own research programs results and an extensive number of experimental data from the literature. The primary aim is the extension of design standards empirical models to the case of RAC with particular emphasis on the effect of replacement ratio on mechanical properties, uniaxial stress–strain curve, fracture energy, and stress–strain softening curve's parameters. It was pointed out that relationships dedicated to assess the mechanical properties of natural aggregate concretes (NAC) are not fully adequate to predict the behavior of RAC. It was established that the elastic modulus Ecm, the tensile splitting strength fctm,sp are related to the mean compressive strength fcm as well as to a parameter taking into account the effect of the recycled aggregates replacement ratio. The validity of many analytical expressions of the stress–strain relationship has been also studied and the effect of replacement ratio was taken into account. The comparison between experimental and analytical stress–strain curves shows that, with the proposed modifications, some models satisfactorily describe the behavior up to failure while others either overestimate or underestimate the postpeak branch. Due to the limited number of available data, no well‐defined relation was found between fracture energy, compressive strength, and formulation parameters.

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“…Subsequently, this type of semi-analytical hinge models have primarily been applied for analysis of fracture in reinforced concrete beams (Olesen 2001a;Kim 2002, 2010;Buratti et al 2011;Carpinteri and Corrado 2011;Castel et al 2011;Visintin et al 2012). Murthy et al (2013) used a hinge model to evaluate bi-linear softening diagrams of plain concrete corresponding to their size independent fracture energy and Wardeh and Ghorbel (2015) used a hinge model to study the effect of frost action on fracture properties and strain softening behavior.…”

Section: Introductionmentioning

confidence: 99%

Cohesive cracked-hinge model for simulation of fracture in one-way slabs on grade

Skar

Poulsen

Olesen

2017

International Journal of Pavement Engineering

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Numerical analysis of slab on grade structures subjected to mechanical loads is a complex matter often requiring computationally expensive models. In order to develop a simplified and general concept for non-linear analysis of slab on grade structures, this paper presents a cohesive cracked-hinge model aimed at the analysis of the bending fracture of the cemented material. The model is based on the fracture mechanics concepts of the fictitious crack model with a linear stress-crack opening relationship. Moreover, the paper presents a two-parameter spring foundation model applied to realistically capture the continuity in the supporting medium. The functionality of the proposed model is compared to numerical analysis with application of the more conventional cohesive zone model. The results obtained show that the methodology is attractive and powerful one well-suited for practical use and further development.

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Prediction of fracture parameters and strain-softening behavior of concrete: effect of frost action

Cited by 29 publications

References 25 publications

Crack propagation speed in ultra high performance concrete (UHPC)

Crack propagation speed in ultra high performance concrete (UHPC)

Mechanical and fracture properties of recycled aggregate concrete in design codes and empirical models

Cohesive cracked-hinge model for simulation of fracture in one-way slabs on grade

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