The lack of interest on the part of the population and the national authorities in strengthening the earthquake resistance of buildings is a consequence of the lack of their own experience with catastrophic natural phenomena. In order to establish an unbiased perception of seismic risk among students, we conducted a seismic stress test of the building stock of the University of Ljubljana. The data for the purposes of this study was mainly provided by the University of Ljubljana, and some of the information was also obtained by inspecting the buildings and project documentation and on the basis of previous analyses. We developed an exposure model for the building stock, which was supplemented by a seismic hazard model, a seismic fragility model and an earthquake impact model for buildings and people. All models were then included in the seismic risk analysis. The results of the study show that the seismic fatality risk at the University of Ljubljana is too high. The average annual return period for loss of life among students is only 6 years, which exceeds the acceptable fatality risk for an updated building stock by a factor of 26. Moreover, the financial losses are too high. The annual cost of repairing seismic damage to the building stock was estimated at EUR 1,040,000, which represents almost a quarter of all funds allocated to the University of Ljubljana from the Development of Funding pillar.
F.12 Improvements to an existing service
COBISS.SI-ID: 37776387The physics-based assessment of seismic risk and its unbiased perception in the community is necessary to enhance community seismic resilience. As a step towards this objective, a seismic stress test of building stock in Slovenia was performed. The stress test outcome was negative, which was communicated to the Ministry of the Environment and Spatial Planning by means of a seismic performance certificate of building stock at the national level. The negative outcome indicates that the seismic risk in Slovenia is too high. About 20% of citizens live in buildings for which the seismic risk expressed by median estimates of time-based risk measures is beyond the long-term acceptable risk. Consequences of a major earthquake (Mw=6.4) close to Ljubljana were simulated informatively by the physics-based method. It was realised for the first time in Slovenia that such an earthquake would likely cause a national catastrophe. The median number of fatalities and direct losses due to damaged building stock was estimated, respectively, to about 600 and 10.5 billion euros, which is more than 20% of Slovenia gross domestic product. It was recommended that seismic resilience in Slovenia is enhanced in two phases: the preparatory and implementation phase. The former phase also foresees seismic performance certificates to improve risk communication and risk management enabled by the novel grading system.
B.04 Guest lecture
COBISS.SI-ID: 61761539In the first part of the report, we demonstrate the seismic risk assessment methodology for an example of a hotel and catering facility. We analyse an existing masonry building, a boarding house in Kranjska Gora, which was built in the 1970s, and then a reconstructed building, which was also seismically strengthened. The purpose of the first part of the document is to show the impact of reconstruction measures on the seismic risk assessment for a masonry building, while the goal of the second part of the report is to present the results by means of the seismic performance certificate of a building. The seismic risk of the existing building was graded with an initial grade E. The calculated probability of collapse for a period of 50 years amounted to 5.8%, and the expected annual loss was equal to 339 € / 100m2 of net area of the building. Therefore, a reduction to grade F in two years is foreseen in the seismic performance certificate. However, an additional reduction to grade G is foreseen in ten years, when the seismic risk will not be acceptable even in the short-term. Thus the owner decided for a comprehensive reconstruction of the building. Part of the building was demolished and rebuilt, and part was strengthened with a reinforced concrete structure. From the seismic performance certificate of the building it follows that the seismic risk for the reconstructed building is long-term acceptable because it is classified to the class of long-term acceptable risk (grade B). The calculated probability of collapse for a period of 50 years was reduced by more than a factor of ten, and the expected annual loss amounts only to 60 EUR / 100m2. Thus, it can be concluded that appropriate measures to reduce seismic risk were envisaged in the building reconstruction. The report is the result of the Seismic Stress Test of the Built Environment project (J2-8159). The methodology for probabilistic seismic risk analysis used is the result of research conducted by UL FGG, IKPIR (Snoj and Dolšek, 2020). The seismic label of a building, which is harmonised with the energy label, was also developed at UL FGG, IKPIR, and first demonstrated in a study for the needs of the Ministry of the Environment and Spatial Planning (Dolšek et al. 2020) and then used in Jamšek's doctoral dissertation (2020). The authors of the seismic label of a building are preparing new publications to explain the entire theoretical background of the seismic label, which purpose is not only to provide information about the seismic risk but also to be used as a tool for long-term risk management (Babič and Dolšek, 2019). With some additional research, it is possible to generalise the seismic label of a building to be applied to all possible facilities.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 8973921The results of the project were also disseminated in the media and at various workshops. Several video presentations of the project results are published on the project website. DOLŠEK, Matjaž (intervjuvanec), BABIČ, Anže (intervjuvanec), ŽIŽMOND, Jure (intervjuvanec). Bo Sloveniji, kjer je zelo nizka potresna odpornost, uspelo prehiteti potres?. 24ur.com, ISSN 1581-3711, 8. 3. 2021. [COBISS.SI-ID 61447171] DOLŠEK, Matjaž (intervjuvanec). Katastrofi kos le s štirimi milijardami. Delo, ISSN 0350-7521. [Tiskana izd.], 9. jan. 2021, leto 63, št. 7, str. 1, ilustr. [COBISS.SI-ID 61326595] DOLŠEK, Matjaž (intervjuvanec). Potresna varnost naj postane del vrednosti nepremičnin. Delo, ISSN 0350-7521. [Tiskana izd.], 9. jan. 2021, leto 63, št. 7, str. 4, ilustr. [COBISS.SI-ID 61328131] DOLŠEK, Matjaž (avtor, intervjuvanec). Potres bi bil za Ljubljano prava katastrofa = [oseba, ki intervjuva] Bojan Rajšek. Delo.si, ISSN 1854-6544. [Spletna izd.], 29. dec. 2020, ilustr. [COBISS.SI-ID 45529091] DOLŠEK, Matjaž (intervjuvanec). Slovenijo bi katastrofalni potres spravil na kolena. Finance, ISSN 1318-1548. [Tiskana izd.], 20. apr. 2016, 1 str., [COBISS.SI-ID 7995745] DOLŠEK, Matjaž (intervjuvanec). O potresih in potresni varnosti Slovenije : oddaja Dnevnikov izbor, RTV Slovenija, 1. program, Ljubljana, 9. 1. 2021. [COBISS.SI-ID 61398019] DOLŠEK, Matjaž (intervjuvanec). Posledice potresa na Hrvaškem in potresna varnost Slovenije : oddaja Globus, RTV Slovenija, 1. program, Ljubljana, 7. 1. 2021. [COBISS.SI-ID 61343491] DOLŠEK, Matjaž (intervjuvanec). Potresno (ne)varne zgradbe : oddaja Dobro jutro, RTV Slovenija, 1. program, Ljubljana, 4. 1. 2021. [COBISS.SI-ID 45619715] DOLŠEK, Matjaž (intervjuvanec). Kako bi potres prestala slovenska mesta : oddaja Danes, Planet TV, 30. 12. 2020. [COBISS.SI-ID 46112515] DOLŠEK, Matjaž (intervjuvanec). Komentar o potresni varnosti v Ljubljani in o potresu v Petrinji 29.12.2020 : oddaja Svet na Kanalu A, 30. 12. 2020. [COBISS.SI-ID 45848323] DOLŠEK, Matjaž, BABIČ, Anže, ŽIŽMOND, Jure. Ali je treba v Republiki Sloveniji krepiti potresno odpornost skupnosti? : usposabljanje predstavnikom lokalnih skupnosti in širši strokovni javnosti o Širši, energetski in potresni prenovi stavb (U6-2), Life projekt CARE4CLIMATE, Ministrstvo za okolje in prostor Republike Slovenije, 24. 3.2021. [COBISS.SI-ID 61414915] DOLŠEK, Matjaž, BABIČ, Anže, ŽIŽMOND, Jure. Potresna obtežba in potresno tveganje v Sloveniji : Slovenski inženirski dan, spletna konferenca Sobivanje s potresi in drugimi naravnimi nesrečami, 4. marec 2021. [COBISS.SI-ID 61402115] DOLŠEK, Matjaž. Ali je treba v Republiki Sloveniji krepiti potresno odpornost skupnosti ? : usposabljanje, Širša, energijska in protipotresna prenova stavb, Life projekt CARE4CLIMATE, Ministrstvo za okolje in prostor Republike Slovenije, Gradbeni inštitut ZRMK, 16.12.2020. [COBISS.SI-ID 61411843]
F.18 Transfer of new know-how to direct users (seminars, fora, conferences)
COBISS.SI-ID: 46112515In the report a seismic stress test of the building of the Faculty of Civil and Geodetic Engineering, University of Ljubljana is performed. For the purpose of the stress test, three linear and four nonlinear models were developed. The models were gradually upgraded so that each model was an upgrade version of the previous one. Special attention was paid to nonlinearities regarding the shear failure and to masonry infills. The results of the stress test show that the probability of the near-collapse limit state (0.7 % in 50 years) exceeds the long-term acceptable risk (3.2% in 50 years). Taking into account the selected models of short-term (3.5% in 50 years) and long-term acceptable risk, the building would be degraded to the lowest grade in six years. It was also found that in the case when the effects of masonry infills and shear failure of reinforced concrete cores are disregarded, the seismic risk is underestimated by a factor of more than four. On the basis of the conceptual proposal for strengthening the building, it can be concluded that the seismic risk can be reduced to an acceptable long-term level if appropriate measures are 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 current estimated shear load-carrying capacities of the reinforced concrete cores.
D.10 Educational activities
COBISS.SI-ID: 8600161