Vol. 5 No 2, 2007 pp. 87 - 94
UDC 624.014.2:624.044(045)=111

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PLASTIFICATION PROCESS OF STEEL FRAMES THROUGH DISCRETIZATION OF PLASTIC ZONE
Esad Mešić
Civil Engineering Faculty, University of Sarajevo, Bosnia and Herzegovina

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Abstract. In the paper there is propose of numerical model for nonlinear analysis of steel frames with use of localized nonlinearity. Main concept of model consists of discret ordering of series nonlinear finite elements – springs Ťzero lengthť in the areas of expected frames plastifikations. The frame elements between the sections with nonlinear elements behaved linear.On that way the forces in the elements of frames for the most degrees of freedom are linear in the relation of displacement, but nonlinear behaviour occurs in relatively small number degrees of freedom. This kind of model can be explicitly introduced in consideration of geometrical imperfection, backward stresses and str.
Key words: Steel Frames, Nonlinear analysis,Semi-rigid connections.

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PRAĆENJE TOKA PLASTIFIKACIJE ČELIČNIH OKVIRA DISKRETIZACIJOM PLASTIČNIH ZONA Predložena metodologija za nelinearnu analizu vrlo kompleksno tretira problematiku čeličnih okvira i primjenjiva je za praktične potrebe. Daje mogućnost uključivanja uticaja normalnih sila na plastifikaciju presjeka. Uključuje u razmatranje pojednostavljenu geometrijski nelinearnu analizu uz imperfekcije elemenata (strukturne i geometrijske) kao i efekte popustljivih veza. Metoda daje mogućnost otkrivanja „istinskog“ mehanizma sloma, sobzirom da je on rezultat nepotpunog mehanizma i velikih pomjeranja (P-?), kao i dobivanje presječnih sila za bilo koji nivo opterećenja.