Modeliranje neidealnih stikov med konstrukcijskimi elementi - Koren, David (D. Koren, 2015)
V diplomski nalogi so najprej predstavljeni nelinearni kontaktni končni elementi, ki jih ponuja komercialni računalniški program SAP2000 (»Nllink« elementi). Na enostavnih primerih je prikazano delovanje najbolj tipičnih izmed njih: linearne in nelinearne osne vzmeti, osne vzmeti tipa »Gap«, »Hook« in »Plastic« ter linearne in nelinearne strižne in zasučne vzmeti. V nadaljevanju pa so le-te uporabljene za modeliranje obnašanja gradbenih konstrukcijskih elementov z neidealnimi stiki, med katerimi so detajlno predstavljeni stiki med sloji slojevitih nosilcev (konzola, T nosilec, žebljani I nosilec) in nelinearni kontakti, ki se pojavljajo v podporah oziroma pri temeljenju (nosilec, temeljna plošča). Na koncu je prikazan še primer analize razpokane kamnite stene modelirane z vzmetmi. Uporabljene so različne vrste analiz: linearna analiza, nelinearna analiza (geometrijsko linearna in geometrijsko nelinearna) ter uklonska analiza. Dobljene rezultate primerjamo tudi z rešitvami iz literature in v večini primerov dosežemo zelo dobro ujemanje. Izkaže se, da se z opisanim principom modeliranja (upoštevanje neidealnosti stika) mnogo bolj približamo dejanskemu obnašanju konstrukcijskih elementov, kar kaže na smotrnost in uporabnost takšnega modeliranja. V programu SAP2000 je takšno modeliranje ugodno in pregledno. Razlike v obnašanju in posledično v sami nosilnosti med konstrukcijskimi elementi z idealnimi oziroma neidealnimi stiki so precejšnje, kar je posebej prikazano na primeru slojevitih konstrukcijskih elementov (žebljani I nosilec). Seveda pa je pri takšnem modeliranju potrebno poznati lastnosti stikov med posameznimi sloji. At the beginning of the present work nonlinear contact finite elements (»Nllink« elements) offered by SAP2000 commercial software program are presented. The behaviour of the most typical elements (linear and nonlinear axial springs, axial springs of the »Gap«, »Hook« and »Plastic« types and also linear and nonlinear springs in shear and bending direction) is shown in simple examples. Such springs are then used for the modeling the behaviour of structural elements with imperfect connections, among which the connections in layered beams are presented in detail (cantilever, T beam, layered timber beam with nailed interfaces). Nonlinearities in restraints and groundwork are also modeled with the presented springs (beam, base plate). Last of all, an example of a stone wall with cracks modeled with springs is analysed. Different types of analyses are used: linear analysis, nonlinear analysis (geometric linear and geometric nonlinear) and buckling analysis. The results of our models are compared with the available data and only small deviations are noticed. It is evident that using the presented method of modeling, which takes imperfect connections into account, we can describe the actual behaviour of structural elements with much more precision. Such modeling therefore appears highly sensible and practical to use, especially with the SAP2000 program, which, in this respect, is highly advantageous and easy to use. The differences in the behaviour and, consequently, in the strength between structural elements with perfect and imperfect connections respectively, are considerable, which is particularly emphasized with the example of layered timber beam with nailed interfaces. The properties of interfaces between layers must obviously be known in such modeling.