diplomska naloga
Tamara Šuligoj (Author), Franc Sinur (Mentor), Janko Logar (Thesis defence commission member), Jože Panjan (Thesis defence commission member)

Abstract

V diplomski nalogi so obravnavane vzdolžno ojačene pločevine obremenjene s čistim tlakom, ki so podvržene pojavu lokalnega in globalnega uklona. Njihova značilnost je, da nosijo tudi v post-kritičnem območju, ko je elastična kritična napetost že prekoračena. Predstavljena so pravila projektiranja po SIST-EN 1993-1-5. Za določitev globalnega redukcijskega faktorja ρc, s katerim reduciramo prerez je potrebno poznati elastično kritično napetost izbočenja pločevine in elastično kritično napetost uklona tlačene palice. Danes se zaradi enostavnosti in učinkovitosti v inženirski praksi za ta namen uporabljajo računalniški programi. V računu nosilnosti po standardu smo kritične napetosti izbočenja panela σcr,p nadomestili s kritičnimi napetostmi izračunanimi s pomočjo programa EBPlate. V programu Abaqus smo izvedli nelinearno geometrijsko analizo z začetnimi nepopolnostimi, s katerimi smo določili dejansko mejno nosilnost vzdolžno ojačanih panelov. Pokazali smo, da postopek računa kritičnih napetosti po SIST-EN 1993-1-5 ne upošteva ugodnega vpliva torzijske togosti ojačitev zaprtega prereza in je zato za določitev mejne nosilnosti ojačanega panela preveč konzervativen. Nasprotno pa uporaba elastične kritične napetosti σcr,p izračunane z EBPlate za ojačitve z zaprtim prečnim prerezom v kombinaciji s postopkom določanja nosilnosti po standardu vodi do rezultatov, ki niso na varni strani. Na podlagi vseh dobljenih rezultatov in ugotovitev smo predlagali novo uklonsko krivuljo, kjer je za posamezen panel izpolnjen pogoj nosilnosti v primeru, da v enačbah uporabimo elastično kritično napetost določeno z računalniškim programom EBPLate.

Keywords

gradbeništvo;diplomska naloga;UNI;jeklene konstrukcije;vzdolžno ojačene pločevine;izbočenje pločevin;torzijska togost;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL FGG - Faculty of Civil and Geodetic Engineering
Publisher: T. Šuligoj
UDC: 624.014.2(043.2)
COBISS: 6716257 Link will open in a new window
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Downloads: 434
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Other data

Secondary language: English
Secondary title: Behaviour of longitudinally stiffened plates subjected to uniform compression
Secondary abstract: The diploma thesis addresses longitudinally stiffened steel plates subjected to uniform compression. Ultimate resistance of such plates is characterised with global and local buckling as they possess substential post-critical resistance after the elastic critical stress has been exceeded. The design rules of SIST-EN 1993-1-5 for the determination of the effective area were discussed. The main focus is set on the computation of the global reduction factor ρ, which is needed to determine the effective area of a plate under compression. For calculation of the global reduction factor ρ, column-like σcr,c and plate-like σcr,p critical buckling stresses need to be determineed. As the equations for the computation of the resistance of longitudinally stiffened plates given by the Eurocode are very complex, the implementation of modern computer programs such as EBPlate into the given design rules has been studied. With a verified numerical model a parametric geometric and material nonlinear analysis with imperfections was carried out to determine the ultimate resistance. It was concluded that the use of SIST-EN 1993-1-5 expresions for elastic critical stress lead to very conservative results as it does not take into account torsional stiffnes of stiffener, which is greater for closed than for open flat stiffeners. However, the use of EBPlate in combination with design rules given in SIST-EN 1993-1-5 may lead to unsafe results in the case of closed stiffeners. Therefore, for plates with closed section stiffeners a new buckling curve is introduced in order to obtain numerical observed resistance, if software EBPlate is used to determine elastic critical buckling stresses.
Secondary keywords: graduation thesis;civil engineering;steel structures;longitudinally stiffened plates;plate buckling;torsional stiffness;
File type: application/pdf
Type (COBISS): Undergraduate thesis
Thesis comment: Univ. v Ljubljani, Fak. za gradbeništvo in geodezijo
Pages: XIV, 86 str.
ID: 8707873