Klaasplastsarrusega betoontalade paindetõmbetugevuse tulekahjujärgne uurimine
Laen...
Kuupäev
2018
Kättesaadav alates
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Raudbetoon on maailmas laialt levinud materjal, kuid armeerimiseks kasutatava terase
puuduseks on selle korrodeerumine. Terassarruse asemel kasutatakse
polümeerkiudsarruseid betoonkonstruktsioonides, mis puutuvad kokku agressiivse
keskkonna, erinevate kloriidide ja hapetega. Kuna polümeerkiudsarrused võrreldes
terassarrustega on suhteliselt uus materjal, siis sellest konstruktsioonide projekteerimiseks
leidub vähe standardeid ja eeskirju. Sealhulgas on vähe uuritud materjali tulepüsivust ja
seega ei ole soovitatud seda kasutada konstruktsioonides, kus tulepüsivuse nõue on tähtis.
Käesoleva magistritöö eesmärgiks on võrrelda klaasplastsarrustega armeeritud talade
tulekahjujärgsete ja kuumutamata katsekehade läbipainet ning paindetõmbetugevust.
Valmistati seitse erinevat katseseeriat, kus igas seerias oli viis katsekeha ehk kokku 35
tükki. Seeriad erinesid kasutatava sarruse läbimõõdu ja valitud betooni kaitsekihi paksuse
poolest. Katsekehade valmistamiseks kasutati armeeringuna klaasplastsarrust Armastek
AKC 6, -8 ja -10 ning betooni survetugevusklassiga C35/45. Katsekehade kuumutamiseks
kasutati propaanipõletit ja katseid viidi läbi välitingimustes. Talade paindetõmbetugevuse
määramiseks sooritati nelja punkti paindetõmbekatse katsemasinaga „ЗИМ П-125“, mille
käigus fikseeriti jõu ja läbipainde väärtused kuni kolme millimeetrini ning lubatud piiril.
Kõigi katsekehade kuumutamisjärgsel vaatlusel selgus, et tekkinud olid esialgsed praod,
mis hiljem paindekatsel arenesid kuni katsekeha purunemiseni. Katsekehad purunesid
põhiliselt kahel viisil – painde mõjul keskelt või põikjõu tõttu toe kohalt. Katsetulemused
näitasid, et tulekahju suurendab oluliselt talade läbipainet, saavutades lubatud väärtuse
väiksema koormuse juures. Kuid samas oli paindetõmbetugevus purunemisel võrdväärne
kuumutamata talade paindetõmbetugevusega. Antud materjali täiendav katsetamine ja
uurimine vastavalt kehtivatele tulepüsivuse standarditele on vajalik.
Reinforced concrete is a widely used material in the world but the problem with the steel used for reinforcement lies in its corrosion. Instead of these, polymer fibre bars are used in the concrete constructions that have contact with aggressive environment, different chlorides and acids. Since glass fibre polymer bars are relatively new in comparison with steel reinforcements, there are very few standards and regulations for engineering these constructions. Also, the fire resistance of the material has been slightly examined and therefore it is not recommended to use it in the constructions where fire resistance requirement is very important. The aim of this master’s thesis is to compare the deflection and flexural strength of the post fire concrete beams reinforced with glass fibre polymer bars and the unheated test pieces. Seven different test series were prepared, where there were five test pieces in each, meaning 35 pieces in total. The series varied in the diameter of the used bars and in the thickness of the concrete protective layer. Glass fibre polymer bars Armastek AKC 6, -8 and -10 were applied for reinforcement and the concrete with the compressive strength class of C35/45 were used for production of specimens. The specimens were heated with the propane torch in field conditions. Four-point flexural tensile test with the test machine ЗИМ П-125 was carried out to find the flexural strength of the beams. During the test, the force and deflection were recorded to the deflection of three millimeters and force value was determined at allowable deflection. While observing the specimens after fire test, it occurred that the first cracks that had initiated in the fire test developed until its fracture in flexural test. The specimens fractured mainly in two ways – in the middle due to bending moment or beside the support due to shear forces. Test results showed that the fire increases sufficiently the deflection of the beams, it also attains the allowable deflection at lower force. However, the flexural strength was equal compared to corresponding values of unheated beams. It is necessary to investigate this material according to valid standard for fire resistance test.
Reinforced concrete is a widely used material in the world but the problem with the steel used for reinforcement lies in its corrosion. Instead of these, polymer fibre bars are used in the concrete constructions that have contact with aggressive environment, different chlorides and acids. Since glass fibre polymer bars are relatively new in comparison with steel reinforcements, there are very few standards and regulations for engineering these constructions. Also, the fire resistance of the material has been slightly examined and therefore it is not recommended to use it in the constructions where fire resistance requirement is very important. The aim of this master’s thesis is to compare the deflection and flexural strength of the post fire concrete beams reinforced with glass fibre polymer bars and the unheated test pieces. Seven different test series were prepared, where there were five test pieces in each, meaning 35 pieces in total. The series varied in the diameter of the used bars and in the thickness of the concrete protective layer. Glass fibre polymer bars Armastek AKC 6, -8 and -10 were applied for reinforcement and the concrete with the compressive strength class of C35/45 were used for production of specimens. The specimens were heated with the propane torch in field conditions. Four-point flexural tensile test with the test machine ЗИМ П-125 was carried out to find the flexural strength of the beams. During the test, the force and deflection were recorded to the deflection of three millimeters and force value was determined at allowable deflection. While observing the specimens after fire test, it occurred that the first cracks that had initiated in the fire test developed until its fracture in flexural test. The specimens fractured mainly in two ways – in the middle due to bending moment or beside the support due to shear forces. Test results showed that the fire increases sufficiently the deflection of the beams, it also attains the allowable deflection at lower force. However, the flexural strength was equal compared to corresponding values of unheated beams. It is necessary to investigate this material according to valid standard for fire resistance test.
Kirjeldus
Magistritöö
Maaehituse õppekaval
Märksõnad
magistritööd, tulepüsivus, paindetõmbetugevus, klaasplast, läbipaine, betoon