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Study of the mechanical properties of glued laminated beech beams is presented in this doctoral thesis. The high strength and stiffness properties of beech wood require that special attention be paid to the tensile strength of different finger joint profiles with different adhesives used for longitudinal gluing of beech boards. The results of experimental testing of finger joints in tension have shown that longer and slimmer finger joints are required to increase the load bearing capacity of finger joints. The influence of the type of adhesive used decreases with the length of the finger joints, so that existing structural adhesives are suitable for use with glued laminated beech beams. Fourteen glued laminated beech beams were produced. The beams were then tested and the strength and stiffness properties were measured. In addition to flexural strength and flexural elastic modulus, shear modulus and contact stiffness between layers were measured. Analytical and numerical models for the analysis of glued laminated beech beams were established. The models are based on Reissner’s planar beam theory and take into account the slip between laminations and the influence of finger joints. The analytical solution for Euler-Bernoulli and Timoshenko-Ehrenfest glued laminated beech beams is presented. The numerical model can be used for modelling glued laminated beams with an arbitrary number of laminations and an arbitrary number of finger joints. The model has been validated with the experimental results and the results agree well. Stochastic analysis of glued laminated beech beams is also performed using analytical and numerical model and the results showed a good agreement with the experimental results and that numerical model can simulate the mechanical behaviour of the glued laminated beech beams. V doktorski disertaciji je predstavljena analiza mehanskih lastnosti lameliranih lepljenih nosilcev iz bukovega lesa. Zaradi visokih mehanskih lastnosti bukovega lesa je potrebno posebno pozornost posvetiti zobatim spojem ter njihovi natezni nosilnosti. Pri tem sta geometrija zobatih spojev in lepilo, ki se uporablja za dolžinsko spajanje bukovih desk, bistvenega pomena. Rezultati eksperimentalnih testov so pokazali, da z daljšimi in ožjimi zobatimi spoji nosilnost zobatega spoja narašča pri tem pa se vpliv lepila zmanjšuje. Obstoječa konstrukcijska lepila so se izkazala kot ustrezna za uporabo v lepljenih lameliranih nosilcih iz bukovega lesa. Štirinajst lameliranih lepljenih nosilcev iz bukovega lesa je bilo testiranih v upogibu. Poleg upogibne trdnosti in upogibnega elastičnega modula lepljenih lameliranih nosilcev iz bukovega lesa, smo izmerili tudi strižni modul nosilcev in togost stika med lamelami. Za analizo lameliranih lepljenih nosilcev iz bukovega lesa sta pripravljena analitični in numerični model. Oba temeljita na Reissnerjevi teoriji ravninskih nosilcev. Pri analizi je upoštevan zdrs med sloji in vpliv zobatih spojev. Analitična rešitev je prikazana za Euler-Bernoullijev in Timoshenko-Ehrenfestov nosilec. Z numeričnim modelom je mogoče modelirati lamelirane lepljene nosilce s poljubnim številom lamel ter poljubnim številom zobatih spojev. Model je validiran z rezultati eksperimentalnih testov in pokazalo se je dobro ujemanje med izracunanimi in izmerjenimi vrednostmi. Za ovrednotenje rezultatov je bila opravljena tudi stohastična analiza, tako z analitičnim, kot tudi numeričnim modelom lameliranega lepljenega nosilca.

V diplomski nalogi je predstavljena problematika masivnih betonov, tj. betonov, pri katerih je potrebna kontrola zaradi povišanja temperature v betonskem prerezu, ki je posledica sproščanja hidratacijske toplote ob vezanju cementa, in s tem povezanim nastankom razpok. Opisana je sestava cementa in vpliv sestave cementa na sproščanje hidratacijske toplote. Hidratacija je opisana po fazah, ki si sledijo med vezanjem cementa. Natančneje sta predstavljeni dve vrsti cementa, in sicer CEM I 42,5 R ter CEM III/B 32,5 N SR-LH, ki se med seboj bistveno razlikujeta glede na količino sproščene hidratacijske toplote. Podan je tudi izraz za opisovanje hitrosti sproščanja toplote med procesom hidratacije. V nadaljevanju naloge je prikazana diskretizacija problema in izpeljava enačb končnega elementa za povezan problem temperature in vlage. Izpeljane enačbe so nato uporabljene za sestavo sistema linearnih algebrajskih enačb, s pomočjo katerega izračunamo vrednosti temperature in koncentracije vlage v izbranih točkah. S pomočjo izpeljanih enačb je bil izdelan računalniški program v programskem okolju MATLAB, ki nam v nadaljevanju služi za numerično temperaturno vlažnostno analizo masivnega betona. V zadnjem delu diplomske naloge so predstavljeni rezultati treh analiz. Najprej analiziramo stopnjo povezanosti problema, pri čemer dobimo pri nepovezanem in delno povezanem problemu pričakovane rezultate. Nasprotno so pri povezanem problemu rezultati nezanesljivi, zato v nadaljevanju slednjega ne obravnavamo.. Z drugo analizo pokažemo, da za oceno temperature in koncentracije vlage v betonu upoštevanje delne povezanosti problema med fazo hidratacije ni potrebno, saj je razlika med povezanim in delno povezanim problemom zanemarljiva. S tretjo analizo pa pokažemo nujnost uporabe cementov z nizko stopnjo hidratacijske toplote pri izdelavi masivnih betonov. The present thesis deals with problems regarding mass concrete, in which the temperature rises due to the heat of cement hydration during the curing phase. A rise of temperature in concrete may result in cracking of young concrete. In the first part of the thesis cement composition and its influence on the released hydration heat is described. The hydration process is explained by its individual phases which occur during hardening of concrete. Two types of cement are presented, the CEM I 42,5 R and CEM III/B 32,5 N SR-LH. The hydration heat released by those two types of cement differs significantly. Also an analytical expression is given for evaluation of heat release of cement. Next, the discretization of the problem and the derivation of the coupled equations is made for a single finite element. The derived equations are used to form a system of linear algebraic equations, which is needed for calculation of the temperature and moisture distribution. Also the derived equations are used to write a computer program in MATLAB environment. The program is used as a tool for numerical hygrothermal analysis of mass concrete. The last part of the thesis presents the results of three different. The purpose of the first analysis is to investigate the influence of the coupling degree between heat and moisture transfer. While the results of non-coupled and semi-coupled models seem reliable, the results of a fully-coupled model are not realistic and therefore are not used in further analyses. The second analysis confirmed there is not much influence of semi-coupling on temperature fields, so the equations can be solved separately and still give useful results. The third analysis shows the necessity of low heat cement use in mass concrete structures.

V diplomski nalogi so predstavljene betonske pregrade in vzroki za nastanek razpok v njih. Predstavljena je tudi zgodovina in energijska zmogljivost hidroelektrarne Moste ter njena mehanska analiza z računalniškim programom CADAM. S programom CADAM je bila določena varnost HE Moste in sicer za različne nivoje razpokanosti pri različnih obtežnih kombinacijah, drenažnih modelih, višinah in naklonih razpok in vrednostih povprečnih horizontalnih pospeškov tal. Poleg tega so bile na osnovi zahtevanih varnostnih faktorjev za zdrs izračunane dopustne dolžine razpok v vseh treh obravnavanih obtežnih kombinacijah. Ugotovljeno je bilo, da ima razpokanost pomemben vpliv na samo varnost pregrade. In the thesis, the influence of cracking on safety of concrete gravity dams has been analysed. This influence has been studied on the case study of hydroelectric power plant Moste. The mechanical analysis has been performed with a computer program CADAM. The safety of the Moste dam has been analysed for various load combinations, drainage systems, crack heights, and values of horizontal ground accelerations. It has been proved that cracking has an important influence on safety of Moste concrete gravity dam.

V diplomskem delu je narejen kratek povzetek o betonskih pregradah, potresih, njihovih značilnostih ter škodi, ki so jo povzročili na betonskih težnostnih pregradah po svetu. Na kratko je predstavljen računalniški program RS-DAM, ki se uporablja za dinamično analizo razpokanih betonskih težnostnih pregrad. S pomočjo programa je narejena analiza stabilnosti pregrade pri različnih lokacijah in usmerjenostih razpoke ter različnih faktorjih trka. Podobna analiza je nato, za primerjavo nekaterih količin, narejena še v programu CADAM. Za geometrijo pregrade je bila uporabljena pregrada Moste na reki Savi, pospeški tal pa so iz akcelerograma potresa, ki se je zgodil leta 2009 v mestu L'Aquilla, v Italiji. In the thesis there is a short summary about concrete gravity dams, earthquakes and the damage they caused on concrete dams around the world. Later on, a computer program RSDAM, that is designed to evaluate the transient response of a cracked section, is presented. This program is then also used to perform a dynamic analysis of a cracked dam, subjected to base accelerations from L'Aquilla earthquake, occurred in 2009 in Italy. The analysis is made for different crack locations and compared with the results of the similar analysis made with computer program CADAM. Geometry used in the analysis is the same as the geometry of the Moste dam, located on river Sava in Slovenia.

V sklopu diplomskega dela sem se seznanjala z vplivi eksplozij na vodne pregrade. Naredila sem zgodovinski pregled napadov na vodne pregrade in njihove poškodbe. Na podlagi pregleda dosegljive literature s tega področja sem se usmerila na učinek udarnega vala, ki ga povzroči eksplozija. Posebej sem obravnavala podvodni udarni val in njegov vpliv na betonsko težnostno pregrado ter pri tem opisala poškodbe učinka udarnega vala. Izvedla sem statično analizo v računalniškem programu CADAM v katerem sem namesto dinamične obremenitve eksplozije uporabila nadomestno statično obtežbo udarnega vala. Ugotovila sem, da ima mesto in količina eksplozivnega materiala pomemben vpliv na varnost obravnavane pregrade. In the thesis, the influence of underwater explosion on safety of concrete gravity dams has been analysed. Moreover, a historical overwiew of various attacks on different dams and their failures has been made based on the available literature. A special attention has been given to the effects of shock wave caused by the explosion. A parametric study has been conducted in a computer program CADAM. The safety of concrete gravity dam Moste, which has been subjected to equivalent static load of the shock wave, has been analysed in detail. It has been found that the position and quantity of the explosive material has a significant influence on safety of concrete gravity dam.