Size Effect in Crack Spacing of Quasi-brittle Materials

Fantilli, Alessandro Pasquale; Frigo, Barbara; Chiaia, Bernardino

doi:10.1016/j.proeng.2015.06.247

“…The post-peak COD can be obtained by accounting for the average crack spacing scr using Fantilli et al, (2015) [38] model for average crack spacing. A full COD description could be obtained by combining the COD measurements for each phase; as illustrated in Figure 2-10, the fracture energy of the material could then be accurately calculated [2].…”

Section: Fracture Energy Of Uhp-frc Concretementioning

confidence: 99%

Response of Ultra-High Performance Fibre Reinforced Concrete Wall Panels to Blast Loading

Sherif¹

2022

Preprint

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Ultra-High-Performance Fibre Reinforced Concrete (UHP-FRC) is a next-generation concrete with outstanding properties in the fresh and hardened state and superior dynamic properties to traditional concretes. This research focuses on the response of UHP-FRC wall panels under blast loading and presents the advantage of using UHP-FRC over traditional concrete in blast-resistant applications while proposing procedures for the practical analysis and design of UHP-FRC blast protection shields. These objectives are achieved through a two-phased experimental investigation and a comprehensive numerical study. The first phase of the experimental program is conducted at Ryerson University. It includes static four-point load testing on six UHP-FRC one-way panels to investigate the effects of different reinforcement ratios (0%, 1%, and 2%) and fibre volumetric ratios (2% and 3%) on flexural response. The experimental results are used as reference static data for the dynamic shock tube testing. The second phase of the experimental program is conducted at the University of Ottawa using a blast load simulator (shock tube) to investigate the dynamic response of UHP-FRC panels to blast loading. Eight one-way simple supported panels of identical dimensions are tested. The parameters investigated are the steel reinforcement ratio (0%, 1%, and 2%), steel fibre volumetric ratio (2% and 3%), and concrete type (UHP-FRC vs. NSC and HSC). Furthermore, the study provides reference data for the validation of the numerical modelling. The test results showed that UHP-FRC outperformed traditional concrete by showing reduced fragmentation and higher ductility and energy absorption. Experimental results also showed that steel reinforcement is critical to the overall performance of the UHP-FRC panels. The numerical investigation included the development of a new constitutive model suitable for UHP-FRC to be used with the concrete damage plasticity model (CDP) for finite element analysis. The numerical simulations are performed using the ABAQUS/Explicit[1] numerical platform. The model is validated against the experimental data from the current study and other published data from the literature, yielding good results. The developed numerical model is further used to conduct a comprehensive design optimization study on UHP-FRC wall panels. The parametric study provides guidelines for selecting optimum design parameters for UHP-FRC blast protection panels.

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“…The post-peak COD can be obtained by accounting for the average crack spacing scr using Fantilli et al, (2015) [38] model for average crack spacing. A full COD description could be obtained by combining the COD measurements for each phase; as illustrated in Figure 2-10, the fracture energy of the material could then be accurately calculated [2].…”

Section: Fracture Energy Of Uhp-frc Concretementioning

confidence: 99%

Response of Ultra-High Performance Fibre Reinforced Concrete Wall Panels to Blast Loading

Sherif¹

2022

Preprint

0

View full text Add to dashboard Cite

Ultra-High-Performance Fibre Reinforced Concrete (UHP-FRC) is a next-generation concrete with outstanding properties in the fresh and hardened state and superior dynamic properties to traditional concretes. This research focuses on the response of UHP-FRC wall panels under blast loading and presents the advantage of using UHP-FRC over traditional concrete in blast-resistant applications while proposing procedures for the practical analysis and design of UHP-FRC blast protection shields. These objectives are achieved through a two-phased experimental investigation and a comprehensive numerical study. The first phase of the experimental program is conducted at Ryerson University. It includes static four-point load testing on six UHP-FRC one-way panels to investigate the effects of different reinforcement ratios (0%, 1%, and 2%) and fibre volumetric ratios (2% and 3%) on flexural response. The experimental results are used as reference static data for the dynamic shock tube testing. The second phase of the experimental program is conducted at the University of Ottawa using a blast load simulator (shock tube) to investigate the dynamic response of UHP-FRC panels to blast loading. Eight one-way simple supported panels of identical dimensions are tested. The parameters investigated are the steel reinforcement ratio (0%, 1%, and 2%), steel fibre volumetric ratio (2% and 3%), and concrete type (UHP-FRC vs. NSC and HSC). Furthermore, the study provides reference data for the validation of the numerical modelling. The test results showed that UHP-FRC outperformed traditional concrete by showing reduced fragmentation and higher ductility and energy absorption. Experimental results also showed that steel reinforcement is critical to the overall performance of the UHP-FRC panels. The numerical investigation included the development of a new constitutive model suitable for UHP-FRC to be used with the concrete damage plasticity model (CDP) for finite element analysis. The numerical simulations are performed using the ABAQUS/Explicit[1] numerical platform. The model is validated against the experimental data from the current study and other published data from the literature, yielding good results. The developed numerical model is further used to conduct a comprehensive design optimization study on UHP-FRC wall panels. The parametric study provides guidelines for selecting optimum design parameters for UHP-FRC blast protection panels.

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“…Galouei and Fakhimi 14 showed that the size and shape of the FPZ can be affected by the specimen size and material ductility, and the size of FPZ tends to expand as the specimen size increases. A multiscale size-dependent model was presented by Fantilli et al 15 based on Euclid’s golden ratio concept, aiming to evaluate crack pattern of quasi-brittle materials at different scales.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of size effect on mixed-mode fracture behavior of epoxy/silica nanocomposites

Ghasemi-Ghalebahman

¹

,

Akbardoost

²

,

Ghaffari

³

2017

The Journal of Strain Analysis for Engineering Design

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The aim of this study was to examine the effect of size on the mixed-mode fracture toughness of quasi-brittle nanocomposites with the help of modified maximum tangential stress criterion. The literature reveals that the effect of size on mixed-mode fracture behavior of brittle nanocomposites has not been well investigated previously using modified maximum tangential stress criterion. The studied nanocomposites were made of epoxy resin reinforced with 7 wt%, 20-30 nm nanosilica. The accuracy of the method was assessed by taking into account the high-order terms of Williams series expansion along with finite element over-deterministic method. To investigate the effect of size on fracture toughness, a number of three-point semi-circular bending tests with different radii and four angles of edge-crack orientation were conducted and subjected to mixed-mode loading. The size of fracture process zone and apparent fracture toughness (K c) were also evaluated as a function of sample size. Experimental results showed that the proposed approach can accurately predict the fracture behavior of studied nanocomposites.

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Size Effect in Crack Spacing of Quasi-brittle Materials

Cited by 5 publications

References 6 publications

Response of Ultra-High Performance Fibre Reinforced Concrete Wall Panels to Blast Loading

Response of Ultra-High Performance Fibre Reinforced Concrete Wall Panels to Blast Loading

Response of Ultra-High Performance Fibre Reinforced Concrete Wall Panels to Blast Loading

Evaluation of size effect on mixed-mode fracture behavior of epoxy/silica nanocomposites

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