PSI - Issue 28

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ScienceDirect

Procedia Structural Integrity 28 (2020) 933–942 Structural Integrity Procedia 00 (2020) 000–000 Structural Integrity Procedia 00 ( 20) 000–000

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© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo Abstract The comprehension of the phenomena caused by fast-transient-loading regimes on structures, such as impact or blast, plays a capi tal role in order to prevent catastrophic failures. In fact, very complex failure modes can occur at these regimes where compression, tensile and shear strengths are involved. The present study investigates the dynamic response of commercial Ultra High Perfor mance Fibre Reinforced Concretes (UHPFRCs) in direct-shear. Four UHPFRCs with di ff erent percentages of fibre reinforcement (1%, 2%, 3% and 4%) were tested at the same high strain-rate level. These results were compared with those obtained on their matrix. They showed that increasing the percentage of fibres enhances the direct-shear strength. The experiments were carried out by means of a Modified Hopkinson Bar device installed in the DynaMat Laboratory. c 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativec mmons.org / licenses / by-nc-nd / 4.0 / ) r-review under responsibility of the European Structural Integrity Society (ESIS) ExCo. Keywords: Ultra High Performance Fibre Reinforced Concrete; direct-shear test; Modified Hopkinson Bar; high strain-rate. 1st Virtual European Conference on Fracture Dynamic response of UHPFRCs in direct-shear tests Ezio Cadoni a, ∗ , Matteo Dotta a , Daniele Forni a , Gianmario Riganti a a University of Applied Sciences of Southern Switzerland - DynaMat Laboratory, Campus SUPSI Trevano, Canobbio 6952, Switzerland Abstract The comprehension of the phenomena caused by fast-transient-loading regimes on structures, such as impact or blast, plays a capi tal role in order to prevent catastrophic failures. In fact, very complex failure modes can occur at these regimes where compression, tensile and shear strengths are involved. The present study investigates the dynamic response of commercial Ultra High Perfor mance Fibre Reinforced Concretes (UHPFRCs) in direct-shear. Four UHPFRCs with di ff erent percentages of fibre reinforcement (1%, 2%, 3% and 4%) were tested at the same high strain-rate level. These results were compared with those obtained on their matrix. They showed that increasing the percentage of fibres enhances the direct-shear strength. The experiments were carried out by means of a Modified Hopkinson Bar device installed in the DynaMat Laboratory. c 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo. Keywords: Ultra High Performance Fibre Reinforced Concrete; direct-shear test; Modified Hopkinson Bar; high strain-rate. 1st Virtual European Conference on Fracture Dynamic response of UHPFRCs in direct-shear tests Ezio Cadoni a, ∗ , Matteo Dotta a , Daniele Forni a , Gianmario Riganti a a University of Applied Sciences of Southern Switzerland - DynaMat Laboratory, Campus SUPSI Trevano, Canobbio 6952, Switzerland Ultra-High Performance Fibre Reinforced Concretes (UHPFRCs) are advanced cementitious material having out standing compressive strength ( ≥ 150MPa) as well as high tensile strength ( ≥ 10MPa) and thanks to the fibre reinforce ment a significant post-cracking tensile capacity. These superior performances are by virtue of a high performance matrix results of a low water-to-cement ratio and low porosity obtained with inclusion of finely-graded sand, silica fume, fly ash and the absence of aggregates exceeding 2 mm size. These characteristics give excellent performance also in terms of durability such as high water and gas impermeability, very high resistance to chloride penetration, carbonation, acid attack. The adding of fibre permits to obtain a fibre-reinforced cementitious materials with notewor thy mechanical performance. These high performances had led to implement UHPFRCs in structural applications as long-span bridges, o ff -shore structures, tall building as well as in refurbishment, strengthening of existing structure or in structural elements with architectural or executive complexities. UHPFRCs are especially suitable where it is requested an enhanced strength, ductility and energy absorption. This is the case of any structures dynamically loaded by impact or blast [Krauthammer (2017); Millard et al. (2018); Astarli- Ultra-High Performance Fibre Reinforced Concretes (UHPFRCs) are advanced cementitious material having out standing compressive strength ( ≥ 150MPa) as well as high tensile strength ( ≥ 10MPa) and thanks to the fibre reinforce ment a significant post-cracking tensile capacity. These superior performances are by virtue of a high performance matrix results of a low water-to-cement ratio and low porosity obtained with inclusion of finely-graded sand, silica fume, fly ash and the absence of aggregates exceeding 2 mm size. These characteristics give excellent performance also in terms of durability such as high water and gas impermeability, very high resistance to chloride penetration, carbonation, acid attack. The adding of fibre permits to obtain a fibre-reinforced cementitious materials with notewor thy mechanical performance. These high performances had led to implement UHPFRCs in structural applications as long-span bridges, o ff -shore structures, tall building as well as in refurbishment, strengthening of existing structure or in structural elements with architectural or executive complexities. UHPFRCs are especially suitable where it is requested an enhanced strength, ductility and energy absorption. This is the case of any structures dynamically loaded by impact or blast [Krauthammer (2017); Millard et al. (2018); Astarli- 1. Introduction 1. Introduction

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo 10.1016/j.prostr.2020.11.066 ∗ Corresponding author. Tel.: + 41-58-666-6377 ; fax: + 41-58-666-6359. E-mail address: ezio.cadoni@supsi.ch 2210-7843 c 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review u der re ponsibility of the European Structural Integrity So i ty (ESIS) ExCo. ∗ Corresponding author. Tel.: + 41-58-666-6377 ; fax: + 41-58-666-6359. E-mail address: ezio.cadoni@supsi.ch 2210-7843 c 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo.