U ovom radu izložena je nova nelinearna statička višemodalna metoda naguravanja uz uključivanje većeg iznosa ekvivalentnog viskoznog prigušenja. Prezentiran je pojam ciljanog ubrzanja, a potom i formulacija postupka za određivanje ciljanog ubrzanja. Ciljano ubrzanje definirano je kao najmanje ubrzanje baze koje dovodi do graničnog stanja nosivosti konstrukcije, i ono predstavlja najnižu potresnu otpornost. Dobivanje ciljanog ubrzanja postiže se iterativnim postupkom višemodalnim naguravanjem po načelu anvelope. Promatrane su dvije kombinacije modova, i to linearna (L) i kombinacija kvadratnog korijena iz sume kvadrata modova (SRSS). Na primjerima a/b okvirnih i mješovitih okvirnih i zidnih sustava pokazano je da je linearna kombinacija nepovoljnija od korijenske kombinacije zbog dobivene niže razine ciljanog ubrzanja. Interferencijom modova na linearnoj i nelinearnoj razini, također je pokazano da je linearna (L) kombinacija učestalije nepovoljnija od korijenske (SRSS) kombinacije modova. U sklopu ovog rada razvijena je nova formulacija određivanja ekvivalentnog viskoznog prigušenja sustava. Provedena je validacija metode ciljanog ubrzanja u višemodalnoj metodi naguravanja a/b okvira s dinamičkim odgovorom sustava. Za dinamičku pobudu korišteni su zapisi akcelelograma stvarnih potresa. Uvažavajući izračunato ekvivalentno viskozno prigušenje te iskoristivost krivulje nosivosti do 3/3 maksimalog pomaka, usporedbom ciljanog ubrzanja višemodalne metode naguravanja i slomnog vršnog ubrzanja podloge dobivenog dinamičkim odgovorom sustava pokazuje se izvrsno slaganje ciljanog ubrzanja i slomnog vršnog ubrzanja podloge. Time je dokazano da je ekvivalentno viskozno prigušenje izračunato prema novoj formulaciji izloženoj u radu realno i da je znatno veće od onog sugeriranog u literaturi. Prezentiran je i praktični postupak određivanja ciljanog ubrzanja u višemodalnoj metodi naguravanja, koji može postati jednostavan postupak za praktičnu nelinearnu statičku analizu armirano-betonskih konstrukcija izloženih potresnom djelovanju.

This thesis presents a new nonlinear static multimodal pushover analysis with the inclusion of a large amount of equivalent viscous damping. The term of target acceleration and the formulation of the procedure for determining the target acceleration are presented. The targeted acceleration is defined as the minimum acceleration of the base that leads to the ultimate limit state of structure, which represents the lowest seismic resistance. The targeted acceleration is achieved with iterative multimodal pushover method according to the envelope principle. Two combinations of modes are analysed, linear (L) and square root of sum of square combination (SRSS). Examples of presented R/C frames and mixed frame and wall system show that the L combination is more unfavourable than the SRSS combination of modes because of the lower level of the target acceleration. Interference of modes on linear and non-linear level also shows that the linear (L) combination is more frequently unfavourable than the root (SRSS) combination of modes. As a part of this thesis a new formulation for determining the equivalent viscous damping of construction is developed. A validation of the targeted acceleration method in multimodal pushover procedure with dynamic response of the R/C frames is conducted. Real earthquake accelerograms are used for seismic excitation. Taking into account the calculated equivalent viscous damping and usability of capacity curve up to 3/3 of maximum displacement, by comparing the targeted acceleration of multimodal pushover method and failure peak ground acceleration obtained by dynamic response of construction proves to be an excellent agreement between the target acceleration and the failure peak ground acceleration. This proves that the equivalent viscous damping calculated according to the new formulation exposed in this thesis is real and that it is significantly higher than what is suggested in the literature. A practical procedure for determining the targeted acceleration in multimodal pushover method was shown, which can also become a simple tool for practical nonlinear static analysis of R/C structures exposed to earthquake action.