The dissemination of information about the risk of losses due to the occurrence of extreme natural events is extremely difficult, since most people do not have personal experience of catastrophic natural disasters that can retard the development of society for many years, or even a decade. For this reason, seismic stress tests are increasingly being used in the field of earthquake engineering as a tool for checking and communicating the earthquake safety of buildings, taking into account both short-term and long-term acceptable risks.
In the scope of this master´s thesis a seismic stress test of the building of the Faculty of Civil and Geodetic Engineering, University of Ljubljana is performed. For the purpose of conducting the stress test, three linear and four nonlinear models were developed. A special attention was paid to nonlinearities regarding the shear failure and to masonry infills. The nonlinear models were gradually upgraded, so that each model was an upgrade version of the previous model.
In the analysis, the damage of the structure and the deformation capacity of the limit states for all calculation models are first determined. On the basis of the pushover curves, a deterministic evaluation is performed, which is included in the standard Eurocode 8. This is followed by the determination of the seismic risk, which is expressed by the probability of the near collapse limit state. Based on the estimated risk and the cumulative risk, the initial grade and the time of grade reduction are, respectively, determined. In the final part, a conceptual proposal for strengthening of the building is presented.
The results of the stress test show that the probability of the near collapse limit state (0.7% / 50 years) exceeds the long-term acceptable risk (3.2% / 50 years). Its seismic risk class was therefore estimated as "B". Taking into account the selected models of short-term (3.5% / 50 years) and long-term acceptable risk, the building's seismic risk class would be re-assessed as "C" after one year, and "D" after six years. It was also found that in the case when the effect of masonry infills is disregarded, as well as the possible shear failure of reinforced concrete cores, then the seismic risk is underestimated by a factor of more than four. On the basis of the conceptual proposal for strengthening of the building, it can be concluded that the building could be re-classified as seismic risk class "A" if appropriate measures were taken. These measures consist of increasing the shear strength of the reinforced concrete cores in the longitudinal direction by 40%, and in the transverse direction by 60%, in comparison with the currently estimated shear load-carrying capacities of the reinforced concrete cores.
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