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V disertaciji so predstavljene obsežne eksperimentalne, analitične in numerične raziskave obnašanja večetažnih zidanih strižnih sten z odprtinami pri potresni obtežbi. Izvedena je ciklična strižna preiskava 3-etažnega preizkušanca, s katero smo preučevali odziv tipične 5-etažne zidane stavbe, grajene na območju Slovenije in njene širše okolice v času pred letom 1964, ko so bili pri nas sprejeti prvi potresni predpisi, na simulirano potresno obtežbo. Rezultati preiskave so potrdili predpostavke in pojasnili mehanizme potresnega obnašanja zidu kot osnovnega elementa, vpetega v celotno strižno steno dejanske zidane konstrukcije. Z analizo rezultatov obsežnih meritev sil in deformacij ter optičnih meritev pomikov na površini strižnih sten med preiskavo večetažnega preizkušanca je bil ugotovljen dejanski sovpliv vertikalnih in horizontalnih elementov celotne strižne stene med potresom, kar je omogočilo realnejšo simulacijo vpetostnih in obtežbenih pogojev med preiskavo posameznega zidu. Z namenom, da bi učinke sodobnih tehnoloških rešitev za protipotresno utrjevanje, ki v praksi še niso v celoti potrjene, tudi eksperimentalno raziskali, je bila preiskava večetažnega preizkušanca prekinjena ob pojavu še popravljivih poškodb. Poškodovan večetažni model je bil utrjen s kompozitnimi oblogami iz malte, armirane s steklenimi vlakni, ter mrež in sider iz steklenih vlaken ter bil nato ponovno preiskan, tokrat do porušitve. Eksperimentalni rezultati kažejo, da je možno z ustreznim načinom utrjevanja zidovja doseči občutno izboljšanje potresnega obnašanja (povečana začetna togost, 50 % višja potresna odpornost, izboljšana deformabilnost). V sklopu disertacije je bil razvit in verificiran makro element, ki omogoča modeliranje cikličnega odziva zidovja ter je sposoben upoštevati tako upogibno kot tudi strižno obnašanje in njuno interakcijo. V zaključnem poglavju je predstavljena tudi validacija učinkovitega inženirskega računskega modela potresne odpornosti osnovnega in utrjenega modela, ki temelji na tvorbi etažnega mehanizma in uporabi referenčne natezne trdnosti zidovja. Extensive experimental, analytical and numerical research on seismic behaviour of multistorey shear walls with openings has been presented in the dissertation. Cyclic shear test of the multistorey specimen to simulate seismic response of the 5-storey high unreinforced masonry building, commonly built in Slovenia and broader region before 1964, when the first earthquake regulations were adopted in Slovenia, has been performed. The results of experimental research, carried out within the framework of this project, confirmed some basic assumptions regarding the mechanism of seismic behaviour of a single wall pier as a structural member of an entire masonry shear wall. The analysis of results of extensive measurements of forces and deformations as well as optical measurements of displacements over the surface of the entire shear walls subjected to seismic loading, made possible a realistic simulation of boundary and loading conditions when testing single wall elements. In order to verify actual efficiency of modern techniques for an aseismic strengthening of existing masonry buildings, which have not been fully confirmed in practice yet, the cyclic shear test of multistorey shear walls has been terminated while major, but still repairable damage developed in the walls. Then, the damaged model was strengthened with fiber reinforced cement mortar based coating and re-tested up to near collapse limit state. The results of the experiment proved that the strengthening of masonry buildings using such technologies is efficient, as significant improvement in seismic behaviour (increased initial stiffness, 50 % higher seismic resistance and improved deformability) has been achieved. Within the framework of the dissertation, a macro element for the modelling of the cyclic response of the masonry has been developed and validated. It is capable of taking into account bending and shear behaviour as well as their interaction. In the final section, the validation of an efficient practical model for the evaluation of seismic resistance of the reference and strengthened building model, based on the formation of storey mechanism and on the application of the referential tensile strength of masonry, is demonstrated.

Doktorsko delo obravnava protipotresno utrjevanje obstoječih konstrukcij s sistemom obložnih križno lepljenih lesenih (CLT) plošč. Izvedena je bila serija monotonih preiskav upogiba križno lepljenih plošč v ravnini, kvazistatičnih cikličnih preiskav neutrjenih in utrjenih zidov iz nearmirane opečne zidovine ter dinamične preiskave neutrjenega in utrjenega dvoetažnega armiranobetonskega (AB) okvirja z ali brez opečnih polnil na potresni mizi. Slednji je bil dimenzioniran v skladu s pravilnikom o protipotresnem projektiranju iz leta 1981 in je bil v osnovi že potresno odporen. Testi opečnih zidov so pokazali, da je možno z mehanskim pritrjevanjem CLT plošč na konstrukcijo povečati nosilnost do 34 %, mejni pomik pa za 165 %. Testi AB okvirja z opečnimi polnili so pokazali, da so CLT ojačitve povrnile nihajne dobe poškodovane konstrukcije v prvotno stanje, zmanjšale so tudi torzijsko podajnost objekta. Delež utrditve je bil sicer dokaj velik v primerjavi z osnovnim objektom. Izdelani so bili numerični modeli ter izračunana potresna odpornost testiranih vzorčnih primerov. Ugotovljeno je bilo, da je s predlaganim sistemom obložnih CLT plošč možno zmanjšati obseg poškodb na testiranih AB okvirju in AB okvirju z opečnim polnilom. Na numeričnem 2D modelu večje stene iz nearmirane opečne zidovine (del fiktivnega dvoetažnega objekta), ki ni izpolnjevala kriterijev za mejna stanja omejevanja poškodb in stanja na meji porušitve, smo po namestitvi ojačilnih plošč, sidranih v medetažno konstrukcijo, povečali njeno potresno odpornost. Obenem je bila izvedena parametrična študija vpliva robnih pogojev na obnašanje konstrukcij iz križno lepljenih plošč z različnimi metodami % modalno analizo s spektri odziva, potisno analizo z N2 metodo ter nelinearno dinamično analizo. Prikazali smo, kako različna togost, nosilnost in duktilnost spojev vpliva na potresno odpornost konstrukcij iz CLT plošč, pomembnost upoštevanja vertikalne obtežbe na stene ter vpliv trenja. Analizirali smo tudi vpliv geometrije sten, ki so lahko sestavljene iz enega večjega ali več manjših kosov. Predlagali smo še postopek za izračun nadomestnih horizontalnih togosti in nosilnosti v ravnini križno lepljenih sten, v kombinaciji z upoštevanjem vertikalne obtežbe, trenja in spojev med lesenimi stenami in medetažami, ki je primeren za inženirsko prakso in omogoča definiranje togosti konstrukcije za modalno analizo s spektri odziva. The doctoral thesis deals with the seismic strengthening of existing structures with a cladding system of cross laminated timber (CLT) plates. An experimental series of monotonic in-plane bending tests of cross laminated timber plates was performed, a quasi-static cyclic testing series of unstrengthened and strengthened unreinforced masonry walls and a series of dynamic tests on a shaking table where a two-story unstrengthened and strengthened reinforced concrete frame with and without masonry infill was analysed. The later was designed according to the demands of the 1981 seismic guidelines and was basically already seismic resistant. The masonry wall tests showed that by using a mechanically connected CLT plate the load bearing capacity can be increased by 34 % and ultimate displacement by 165 %. The RC frame tests with masonry infill showed that the CLT strengthening plates caused the vibration periods of an already damaged structure to return back to their initial state, the building%s torsional flexibility was also decreased. However, the proportion of the strengthening was quite large compared to the basic structure. Numerical models of the tested structures were made, their seismic resistance was calculated. It was found that the proposed CLT cladding strengthening system can reduce the extent of damage on the tested RC frame and frame with masonry infill. A 2D numerical model of a larger unreinforced masonry wall (part of a fictional case study building) that didn%t meet the damage limitation and near collapse limit states, showed that after the instalment of the CLT plates anchored into the floor structure the wall%s seismic resistance was increased. In addition, a parametric study of the influence of boundary conditions on the seismic behaviour of cross laminated timber buildings is performed with different analysis types % a modal analysis with elastic spectrum response, a pushover analysis with the N2 method and a nonlinear dynamic analysis. We have demonstrated how different stiffness, strength and ductility of connections influences on the seismic resistance of CLT structures, the importance of taking the vertical load acting on walls into account as well as the influence of friction. We have also analysed the influence of wall geometry that can be built from either one larger or several smaller pieces. Also, a procedure for the calculation of a wall%s in plane substitute stiffness and strength considering the influence of the vertical load, friction and connections among timber walls and floors is proposed, which is suitable for the engineering practice and allows the definition of a structure%s stiffness for the modal analysis with the response spectra.

V diplomski nalogi je bila narejena parametrična nelinearna seizmična analiza kamnite zidane stavbe v Čezsoči. V prvem delu naloge je opravljen pregled metod preskušanja, ki so osnova za projektiranje obstoječih stavb, saj je od njih odvisna raven poznavanja konstrukcije. Poudarek je na neporušnih metodah, ki so izmed vseh metod najbolj zaželene in obenem zaradi nenehnega razvoja tehnike predstavljajo hitro razvijajoče se in obetavno področje. V nadaljevanju je opisan postopek preverjanja potresne odpornosti obstoječih zidanih stavb v skladu s sodobnimi standardi. Razloženi so različni mehanizmi porušitve strižno obremenjenih nearmiranih zidanih elementov. Po korakih je opisana poenostavljena N2 metoda. V praktičnem delu je predstavljena obravnavana stavba in rezultati opravljenih in-situ preiskav. Parametrično analizo smo naredili z dvema programskima paketoma (Sremb in 3Muri) za nelinearno seizmično analizo zidanih konstrukcij. Pri tem smo določali potresno odpornost v odvisnosti od parametra poznavanja konstrukcije, izbire ustreznega porušnega mehanizma, upoštevanja varnostnih faktorjev ter utrditve stavbe s postopkom injektiranja. Pokaže se, da s sistematičnim injektiranjem lahko dosežemo zahteve sodobnih standardov. Zaradi različnih predpostavk v obnašanju stavbe med potresom se rezultata potresne odpornosti, dobljena z različnima programskima paketoma, lahko močno razlikujeta. Razlike nastopijo tudi zaradi predpostavljenega porušnega mehanizma. Pokaže se, da je investiranje v predhodne preiskave smiselno, saj se lahko ob upoštevanju dejanskih materialnih karakteristik bistveno bolj približamo razpoložljivi potresni odpornosti konstrukcije. IV In the diploma, a parametric analysis of seismic resistance of a stone masonry building in Čezsoča was performed. The first part presents an overview of the testing methods being the basis for redesign of existing buildings since they define the depth of knowledge of the construction. The emphasis is on non-destructive testing, which is preferred due to its characteristics and continuous development in technology, presenting a quickly developing and promising area. Next, we described the process of assessment of seismic resistance of existing masonry buildings in accordance with contemporary standards. Different mechanisms of shear failure for unreinforced masonry walls are explained. The simplified N2 method is presented step by step. In the practical part of the thesis, the analyzed building and the results of in-situ testing are presented. The parametrical analysis was carried out using two programs (Sremb and 3Muri) for non-linear seismic analysis of masonry structures. We defined the seismic resistance in dependence of the parameter of knowledge of the construction, the choice of an appropriate failure mechanism, consideration of safety factors and strengthening the building with grout technique. The results of the analysis show that the requirements of contemporary standards can be fulfilled by systematic grouting. Due to different suppositions for the behaviour of the building under seismic loading, the results of seismic resistance achieved using the two programs differ significantly. The differences appear also due to the presumed failure mechanism. Investment in preliminary in-situ testing is valuable since it is possible to come much closer to the available seismic resistance while considering the actual material characteristics.

V diplomski nalogi sta izdelana dva modela za oceno potresne odpornosti povprečne zidane hiše na širšem območju Škofje Loke. V začetnem poglavju obravnavamo obnašanje zidanih konstrukcij in možne porušne mehanizme njihovih elementov. V nadaljevanju je predstavljeno teoretično ozadje metode N2, ki je vključena v Evrokod 8 in s katero smo določili potresno odpornost obravnavanih zidanih objektov. Analizirali in interpretirali smo rezultate analiz za 11 hiš, ki se nahajajo v širšem območju Škofje Loke in so bile zgrajene v letih od 1970 do 1990. Na osnovi načrtov Projektov za pridobitev gradbenega dovoljenja smo vrednotili srednje vrednosti in koeficient variacije za izbrane geometrijske lastnosti stavb, ki imajo pomemben vpliv na njihovo obnašanje. Pričakovani delež tlorisnih površin sten glede na neto površino etaže znaša 11–12 %, delež efektivnih tlorisnih površin sten pa se giblje v območju 60-90 % bruto površine sten, pri čemer je odvisen od smeri objekta. Povprečen zid je širok 2,4 m, njegova efektivna višina pa znaša 80 % etažne višine objekta. V primerjavi izbranih lastnosti hiš s sorodnimi podatki, ki so dostopni na spletnem portalu e-Prostor, smo ugotovili večja odstopanja v vrednostih le teh. Nelinearno statično (potisno) analizo smo izvedli s programom 3Muri. Rezultati so pokazali, da so najbolj ranljivi medokenski slopi zidu, delno pa tudi prekladni deli. Običajno pri mejnem stanju blizu porušitve nastopa kombinacija upogibnih in strižnih poškodb. Glede na mejni pospešek smo izbrali merodajne potisne krivulje in jih normirali glede na težo objekta in njegovo višino oziroma glede na povprečno efektivno tlorisno etažno površino sten v obravnavani smeri in višino objekta. S tem smo dobili dva modela normiranih potisnih krivulj. Pričakovana maksimalna dosežena nosilnost v šibki smeri objekta znaša 15 % celotne teže stavbe oziroma dobrih 60 kN na kvadratni meter efektivne tlorisne površine sten. Prikazana je uporaba modelov na primeru dveh objektov in dodana ocena potresne odpornosti za mejno stanje močnih poškodb, ki kaže na to, da večina obravnavanih objektov ne izpolnjuje zahtev Evrokoda 8-3. Two models for seismic performance assessment of masonry houses in Škofja Loka region are developed. In first chapters the behaviour of masonry buildings under seismic actions with an emphasis on failure mechanisms of structural components are discussed. Follows an overview of the theoretical background of N2 method, which is included in the Eurocode 8 and which was used for determination of the seismic resistance of examined masonry structures. The results of numerical investigation of 11 masonry houses, built in the years from 1970 to 1990, are then presented and discussed. The project design for building permit was used to obtain input data of the buildings. The mean values and the coefficient of variation were assessed for those geometrical features of the buildings, which have great impact on the seismic performance assessment of the buildings. Expected percentage of the floor surface area of the walls in relation to the net surface of the floor varied from 11 to 12 % with respect to the direction of building. The proportion of the effective floor area of the walls is in the range from 60 to 90% of the gross surface area of the walls depending on the direction of the building. Average wall is 2,4 m wide and its effective height amounts to 80 % of the building`s floor height. It was found that the selected characteristics of houses with the corresponding data which are available on the web portal e-Prostor, are significantly different. Nonlinear static (pushover) analysis was performed by using computer software 3Muri. The results show that the combination of bending and shear damage occurred in piers and also spandrels in the region of deformation close to the ultimate limit state. Two models of the normalized expected pushover curves were obtained by taking into account the pushover curves which had a decisive impact on the seismic limit-state peak ground acceleration. The base shear was normalized by the weight of the building or with respect to the average effective floor area of the walls in the given direction and whereas the top displacement was normalized only by the building’s height. Maximum expected capacity in weak direction amounted 15 % of the total weight of the building and more than 60 kN per square meter of effective floor area of the walls. In the last chapter the normalized pushover curves were used for seismic performance assessment of two houses for which it was found that do not fulfil requirements of standard Eurocode 8-3.

V diplomski nalogi je izdelana ocena potresne odpornosti stare upravne stavbe Rudnika živega srebra Idrija. V prvem delu naloge je predstavljeno obnašanje zidanih stavb med delovanjem potresa in opis tipičnih porušnih mehanizmov zidov. Sledi kratek opis določil standarda Evrokod 8-3, ki obravnava področje ocenjevanja obnašanja obstoječih stavb med potresi. Po korakih je opisana poenostavljena metoda N2, ki temelji na nelinearni statični analizi. Na koncu sledi še predstavitev programa 3Muri, ki smo ga uporabili za račun potisnih krivulj. V drugem delu naloge je sprva opisana upravna stavba, ki je zgrajena iz nepovezanih kamnitih in opečnih zidov. Zaradi nepoznavanja dejanske kvalitete obstoječih materialov smo za obe vrsti zidovja iz literature privzeli po tri nabore mehanskih lastnosti. Pripravili smo pet modelov z različnimi kombinacijami vrednosti mehanskih lastnosti opečnega in kamnitega zidovja, na podlagi katerih smo ocenili potresno odpornost konstrukcije. Na osnovi deterministične analize smo ugotovili, da stavba ni sposobna prenesti pričakovanega projektnega pospeška temeljnih tal ag = 0,23 g in tako ne izpolnjuje zahtev standarda Evrokod 8. Velika ranljivost konstrukcije je bila posledica zelo nizkih vrednosti strižnih trdnosti privzetih materialov, ki smo jih skladno s standardom Evrokodom 8-3 delili še s faktorjem zaupanja CF = 1,35. Različne kombinacije mehanskih lastnosti zidovja so povzročale različne oblike porušnih mehanizmov konstrukcije. Zaradi majhnih razlik med strižnimi trdnostmi privzetih materialov se potresne odpornosti posameznih modelov niso bistveno razlikovale. Vrednosti koeficientov potresne odpornosti SRCu so variirali med 0,09 in 0,12, kar se je dobro ujemalo z vrednostjo, ki je bila ocenjena v projektu POTROG (2013). Ocenjujemo, da so mejni pospeški tal za obravnavan objekt verjetno podcenjeni, kar je posledica varnostnih faktorjev, ki jih je potrebno upoštevati v primeru nepopolnega poznavanja konstrukcije. In this thesis, the seismic performance assessment of the former administration building of RŽS Idrija is investigated. The first part of the thesis presents the behaviour of masonry buildings under seismic actions, and typical failure mechanisms of masonry walls, followed by the provisions of the Eurocode 8-3 standard, which deal with seismic assessment of existing buildings. Further on, the simplified N2 method based on non-linear static (pushover) analysis is introduced, followed by the presentation of 3Muri software. The second part of the thesis begins with a description of the administration building, which was build out of stone and brick masonry walls without adequate floor-to-wall connections. Not knowing the exact quality of the existing materials, three sets of mechanical properties for both types of masonry were obtained from the literature. The seismic performance assessment was based on five models of the structure each with different combination of mechanical properties of stone and brick masonry. The results of the deterministic analysis have shown that the building is incapable of withstanding the expected design ground acceleration ag = 0,23 g and does not meet the requirements of the Eurocode 8 standard. The great vulnerability of the structure is a consequence of very low shear strength values of the masonry, which were assessed from previous studies and, in accordance with Eurocode 8-3, divided by the confidence factor CF = 1,35. Different combinations of mechanical properties of masonry have lead to different types of failure mechanisms of the structure. Due to small differences between shear strength values of the materials the seismic resistance of our models did not differ significantly. The seismic shear coefficient SRCu was between 0,09 and 0,12 which complied with the coefficient estimated in the POTROG (2013) project. It is estimated that the limit-state peak ground acceleration is most likely underestimated, which is the consequence of safety factors that need to be considered in the case of incomplete knowledge of the structure.