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Making communities safer requires better tools to identify, quantify, and manage risks. Among the most important tools are stress tests, originally designed to test the risk posed by nuclear power plants. A complementary harmonized multilevel stress test for nonnuclear civil infrastructure systems against natural hazards is proposed. Each stress test level is characterized by a different scope and a different level of risk analysis complexity to suit different civil infrastructure systems, different hazards, and different risks. The stress test consists of the following phases. First, the goals and the methods for the risk analysis are defined. The test is then performed at the component and system levels, followed by a verification of the findings. A penalty system is defined to adjust the output of the risk assessment according to the limitations of the risk analysis methods used. The adjusted risk assessment results are then passed to a grading system to determine the outcome of the stress test. Finally, the risk assessment results are reported, and the stress test outcomes are communicated to stakeholders and authorities.

This paper provides an overview and introduction to the development of non-ergodic ground-motion models, GMMs. It is intended for a reader who is familiar with the standard approach for developing ergodic GMMs. It starts with a brief summary of the development of ergodic GMMs and then describes different methods that are used in the development of non-ergodic GMMs with an emphasis on Gaussian process (GP) regression, as that is currently the method preferred by most researchers contributing to this special issue. Non-ergodic modeling requires the definition of locations for the source and site characterizing the systematic source and site effects; the non-ergodic domain is divided into cells for describing the systematic path effects. Modeling the cell-specific anelastic attenuation as a GP, and considerations on constraints for extrapolation of the non-ergodic GMMs are also discussed. An updated unifying notation for non-ergodic GMMs is also presented, which has been adopted by the authors of this issue.

The seismic exposure of urban areas today is much higher than centuries ago. The 2020 Zagreb earthquake demonstrated that European cities are vulnerable even to moderate earthquakes, a fact that has been known to earthquake-engineering experts for decades. However, alerting decision-makers to the seismic risk issue is very challenging, even when they are aware of historical earthquakes that caused natural catastrophes in the areas of their jurisdiction. To help solve the issue, we introduce a scenario-based risk assessment methodology and demonstrate the consequences of the 1895 Ljubljana earthquake on the existing building stock. We show that a 6.2 magnitude earthquake with an epicentre 5 km north of Ljubljana would cause many deaths and severe damage to the building stock, which would likely lead to direct economic losses higher than 15% of the GDP of the Republic of Slovenia. Such an event would be catastrophic not only for the community directly affected by the earthquake but for the entire country. We have disseminated this information over the course of a year together in addition to formulating a plan for enhancing the community seismic resilience in Slovenia. Hopefully, local decision-makers will act according to their jurisdiction in Slovenia and persuade decision-makers across Europe to update the built environment renovation policy at the European level.

The estimation of building seismic risk and loss utilising response history analysis is challenging, especially because the final objective is the seismic loss estimation for building stock. In this paper, this challenge is addressed by developing a simplified nonlinear structural model, which is capable of simulating the seismic response of predominantly plan-symmetrical reinforced concrete frame buildings subjected to ground motions in both horizontal directions. The simplified structural model is plugged into the direct seismic risk and loss estimation methodology. Its capabilities are then demonstrated by estimating the seismic risk and losses for a four-storey office building and a five-storey school building. For the analysed buildings, it is shown that the frequency of collapse, the expected annual loss and the frequency of exceedance of a given loss can be simulated with the same level of accuracy as in the case of the conventional structural model, but with greater numerical robustness and computational efficiency. Research is needed to better define the limitations of the introduced simplified model and extend the capabilities of simplified nonlinear models to more complex structural systems of plan-asymmetrical buildings.

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This paper provides an overview and introduction to the development of non-ergodic ground motion models, GMMs. It is intended for a reader who is familiar with the standard approach for developing ergodic GMMs. It starts with a brief summary of the development of ergodic GMMs and then describes different methods that are used in the development of nonergodic GMMs with an emphasis on Gaussian Process (GP) regression, as that is currently the method preferred by most researchers contributing in this special issue. Non-ergodic modeling requires the definition of locations for the source and site characterizing the systematic source and site effects; the non-ergodic domain is divided in cells for describing the systematic path effects. Modeling the cell-specific anelastic attenuation as a GP, and considerations on constraints for extrapolation of the non-ergodic GMMs are also discussed. An updated unifying notation for non-ergodic GMMs is also presented, which has been adopted by the authors of this issue.

No abstract