Sekundarni jezik: |
Angleški jezik |
Sekundarni naslov: |
Proof of safety of prestressed hollow core slab under normal and fire conditions |
Sekundarni povzetek: |
This graduation thesis deals with pre-stressed hollow-core slab. In the first step, in accordance with Eurocodes, slab safety is presented. For designed influences, prestressed cables are designed and tension force, conditions of decompression, limitations of tension and crack width and bending and shear failure safety are determined. In the next step we focus on the analysis of prestressed slab under fire conditions. For fire safety proof, simple and advanced calculation models are used. Among simple models the method isotherm 500°C is used. Models are divided in two unrelated parts, the first is temperature, the second is mechanical analysis. In thermal analysis, considering fire conditions, we determine time dependent temperature distribution over the cross-section of the slab. Closed air cells are considered. We also assume that the panel is exposed to standard fire temperature-time curve. Mechanical analysis consists of the proof of slab fire safety. Using isotherm 500°C, the capacity of cross-section is checked. In advanced calculation model we analyze stress-strain state of slab during fire, all the way to the calculated failure. The simple calculation model of isotherm 500°C shows larger fire resistance than in the case of using advanced calculation model, which is contrary to expectations. Using isotherm 500°C, section failure occurs due to cable yield at high temperatures, while using advanced model, due to viscousious creep of prestressing steel. |
Sekundarne ključne besede: |
civil engineering;graduation thesis;pre-stressed hollow-core slab;fire resistance;temperature;capacity;fire analysis;simple and advanced calculation model; |
Vrsta datoteke: |
application/pdf |
Vrsta dela (COBISS): |
Diplomsko delo |
Komentar na gradivo: |
Univ. v Ljubljani, Fak. za gradbeništvo in geodezijo |
Strani: |
XIV, 84 str. |
Vrsta dela (ePrints): |
thesis |
Naslov (ePrints): |
Proof of safety of prestressed hollow - core slab under normal and fire conditions |
Ključne besede (ePrints): |
prednapeta votla plošča;požarna odpornost;temperatura;nosilnost;požarna analiza;poenostavljena in napredna računska metoda |
Ključne besede (ePrints, sekundarni jezik): |
pre-stressed hollow-core slab;fire resistance;temperature;capacity;fire analysis;simple and advanced calculation model |
Povzetek (ePrints): |
V diplomski nalogi obravnavamo prednapeto votlo ploščo. Najprej dokazujemo varnost plošče na mejna stanja v pogojih normalne uporabe skladno z Evrokodi. Za predvidene vplive projektiramo prednapete kable, določimo napenjalno silo ter preverimo pogoje dekompresije, omejitve napetosti in širino razpok ter varnost proti upogibni in strižni porušitvi. V nadaljevanju se posvetimo še analizi prednapete plošče v pogojih požara. Uporabimo poenostavljeno in napredno računsko metodo za dokazovanja požarne varnosti. Izmed poenostavljenih metod izberemo metodo izoterme 500°C. Obe računski metodi razdelimo v dva nepovezana dela in sicer v temperaturno in mehansko analizo. Pri temperaturni analizi glede na toplotni vpliv določimo časovno razporeditev temperatur po obravnavani plošči. Upoštevamo vpliv zaprtih zračnih celic. Pri tem predpostavimo, da je plošča izpostavljena standardni požarni krivulji temperatura-čas. V mehanski analizi preverjamo požarno varnost plošče. Pri izotermi 500°C preverjamo odpornost kritičnega prečnega prereza, pri napredni računski metodi pa analiziramo napetostno in deformacijsko stanje plošče med požarom vse do računske porušitve plošče. Ugotovimo odstopanje rezultatov. S poenostavljeno metodo izoterme 500°C je požarna odpornost plošče večja kot pri analizi z napredno metodo kar je v nasprotju s pričakovanji. Pri izotermi 500°C porušitev prereza nastopi zaradi plastifikacije kablov pri povišanih temperaturah, pri napredni metodi pa zaradi viskoznega lezenja jekla za prednapenjanje. |
Povzetek (ePrints, sekundarni jezik): |
This graduation thesis deals with pre-stressed hollow-core slab. In the first step, in accordance with Eurocodes, slab safety is presented. For designed influences, prestressed cables are designed and tension force, conditions of decompression, limitations of tension and crack width and bending and shear failure safety are determined. In the next step we focus on the analysis of prestressed slab under fire conditions. For fire safety proof, simple and advanced calculation models are used. Among simple models the method isotherm 500°C is used. Models are divided in two unrelated parts, the first is temperature, the second is mechanical analysis. In thermal analysis, considering fire conditions, we determine time dependent temperature distribution over the cross-section of the slab. Closed air cells are considered. We also assume that the panel is exposed to standard fire temperature-time curve. Mechanical analysis consists of the proof of slab fire safety. Using isotherm 500°C, the capacity of cross-section is checked. In advanced calculation model we analyze stress-strain state of slab during fire, all the way to the calculated failure. The simple calculation model of isotherm 500°C shows larger fire resistance than in the case of using advanced calculation model, which is contrary to expectations. Using isotherm 500°C, section failure occurs due to cable yield at high temperatures, while using advanced model, due to viscousious creep of prestressing steel. |
Ključne besede (ePrints, sekundarni jezik): |
pre-stressed hollow-core slab;fire resistance;temperature;capacity;fire analysis;simple and advanced calculation model |
ID: |
8311968 |