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Raziskava odpornosti visoko zmogljivega vlaknastega betona proti udarni obtežbi projektila : magistrsko delo
Kravanja, Sebastjan (Author), Bokan-Bosiljkov, Violeta (Mentor) More about this mentor... This link opens in a new window, Sovják, Radoslav (Co-mentor)

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Abstract
Visoko zmogljivi vlaknasti betoni predstavljajo učinkovito rešitev pri zagotavljanju odpornosti proti različnim udarnim obtežbam. V okviru magistrskega dela je bila opravljena eksperimentalna raziskava odpornosti visoko zmogljivega vlaknastega betona proti udarni obtežbi deformabilnega in nedeformabilnega projektila pri visokih hitrostih. Visoko zmogljiva betonska matrica s tlačno trdnostjo nad 110 MPa je bila ojačena z diskretnimi jeklenimi vlakni v petih različnih prostorninskih deležih od 0,125 % do 2,0 %. Udarna odpornost je bila ovrednotena preko treh glavnih porušnih količin: globina prodiranja ter površina in prostornina kraterja. Potrjeno je bilo, da višanje prostorninskega deleža vlaken ne prispeva bistveno k zmanjšanju globine prodiranja, vendar je zelo učinkovito pri zmanjšanju površine in prostornine kraterja, saj se jeklena vlakna aktivirajo po razpokanju betonske matrice in pri tem materialu zagotovijo rezidualno trdnost. Preizkušeno je bilo veliko število empiričnih in delno-analitičnih materialnih modelov za napoved globine prodiranja ter izmeta mase, ki so bili ocenjeni glede na povezanost z rezultati eksperimentalne raziskave. Ugotovljeno je bilo, da rezultate najbolje opišejo novejši delno-analitični modeli, ki so bili razviti na podlagi natančnejših fizikalnih osnov. Preizkušena je bila hipoteza, da enoosna tlačna trdnost na udarno odpornost betonskega kompozita nima glavnega vpliva, kot antiteza osnovni predpostavki večine materialnih modelov, da je globina prodiranja obratno sorazmerna kvadratnemu korenu enoosne tlačne trdnosti. Zveza med porušnimi količinami in standardnimi mehanskimi lastnostmi je bila statistično ovrednotena. Dokazano je bilo, da imata na globino prodiranja večji vpliv natezna in upogibna trdnost, na prostornino in površino kraterja pa v večji meri vpliva enoosna tlačna trdnost. Analiza strižnih razpok je pokazala, da višanje deleža vlaken zagotavlja tudi višjo odpornost proti oblikovanju razpok.

Language:Slovenian
Keywords:visoko zmogljiv beton, vlaknast beton, jeklena vlakna, HPC, HPFRC, UHPC, UHPFRC, projektil, udarna odpornost, materialni modeli
Work type:Master's thesis/paper (mb22)
Tipology:2.09 - Master's Thesis
Organization:FGG - Faculty of Civil and Geodetic Engineering
Year:2017
Publisher:[S. Kravanja]
UDC:691.32(043.3)
COBISS.SI-ID:8265057 Link is opened in a new window
Views:645
Downloads:571
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Secondary language

Language:English
Title:Resistance of high performance fiber reinforced concrete under projectile impact loading : master's thesis
Abstract:
High performance fiber reinforced concretes presents an effective solution for providing impact resistance to different impact loading. An experimental investigation of resistance of high performance fiber reinforced concrete against deformable and non-deformable projectile impact at high velocities was conducted in the framework of this master’s thesis. High performance concrete matrix with compressive strengths over 110 MPa was reinforced with discrete steel fibers in five different volumetric fractions from 0,125% to 2,0%. Impact resistance of the composite was evaluated through three main damage degrees: depth of penetration and area and volume of the impact crater. It was confirmed, that the increment of fiber volumetric fraction does not have significant influence on the depth of penetration, but is very effective in reducing the crater area and volume, since the fibers are activated after the cracking occurs and are thus providing the residual strength to the material. A large number of empirical and semi-analytical material models for predicting penetration depth and mass ejection were tested and evaluated through comparison to the experimental results. The best correlation to experimental results was provided by newest models, which were developed on the basics of more accurate physical assumptions. The hypothesis, that unconfined compressive strength does not have the main influence on impact resistance, was tested as an antithesis to the basic assumption from which the majority of the material models are derived, that the depth of penetration is in inverse correlation to the square root of unconfined compressive strength. It was proven, that the depth of penetration is more influenced by concrete tensile and flexural strength, while crater volume and area are in majority controlled by unconfined compressive strength. Shear crack analysis showed, that the increment in fiber volumetric fraction provides higher impact crack resistance.

Keywords:high performance concrete, fiber reinforced concrete, steel fibers, HPC, HPFRC, UHPC, UHPFRC, projectile, impact resistance, material models

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