Many studies have demonstrated that the design of structures in a region through the uniform hazard principle does not guarantee a uniform collapse risk. Even in regions with similar Peak Ground Accelerations (PGAs) corresponding to the same mean return period, the seismic risk in terms of collapse probability will be significantly different mainly due to the shape of the hazard curves as well as uncertainties in structural capacities. In this paper, risk-targeted hazard mapping is being explored in peninsular Spain using a recently updated seismic hazard map. Since risk targeting involves multiple input parameters such as the model parameters of fragility curves, their variability was considered through their probability distribution as observed in reinforced concrete (RC) moment frame buildings, representing the most common building typology in Spain. The influence of the variation of these parameters on the risk results were investigated, and different assumptions for estimating the model parameters of fragility curves are illustrated. These assumptions were included in a fixed (generic) fragility curve or building-site-specific fragility curves. Different acceptable damage states (i.e., collapse and yielding) were considered concerning Spain’s seismicity level. Finally, the maps for risk-targeted design ground motions and risk coefficients are presented. It is outlined that the employment of risk-targeted analysis leads to the modifications for existing design ground motions due to the different shape of the hazard curves across Spain and considering the uncertainty of structural capacity. Moreover, it is found that using the building- and site-specific fragility curves could result in a more uniform seismic risk across the country.
South and SouthEast of Spain are the regions with a higher seismic hazard in Spain. Therefore, a regional normative, focused on the importance of developing seismic emergency planning in many of the municipalities of the Valencian community, was established in 2011. consequently, all the municipalities in Alicante province have to develop a seismic emergency planning. however, only Elche and Alicante have completed the seismic risk analysis and they have started to prepare their emergency plans which will be finished before the end of 2019. This paper shows the main results of the seismic risk analysis carried out in both municipalities. The seismic hazard update in the region has shown that the main earthquake scenarios, which may hit both cities, correspond to the crevillente and the Bajo Segura faults (also responsible for damaging historical earthquakes). In both cases, the urban areas are on a sedimentary deposit, which can reach hundreds of meters so site effects and possible site-building resonance can be important. Additionally, most of the building stock belongs to periods without seismic normative, increasing, therefore, their vulnerability and the obtained damage. The mean damage ratio for a magnitude of 5.5 increases from a 0.8% to a 10.3% at Alicante and Elche, respectively. Besides, if the magnitude increases to a 6.5 then the mean damage ratio increases from a 16.6% to a 60.3%. In conclusion, we recommend that the emergency planning developed for both municipalities has to take into consideration that even the occurrence of a probable earthquake (475 yrs return period) corresponding to a mw 5.5 will affect both cities so the procedures and protocols should be written in close cooperation.
South and SouthEast of Spain are the regions with a higher seismic hazard in Spain Consequently, all the municipalities in Alicante province has to develop seismic emergency planning. Besides, the south of Alicante province and, in particular, the cities of Elche and Alicante are located in a sedimentary deposit, which can reach hundreds of meters, so site effects can be important. Additionally, most of the building stock belongs to periods without seismic normative, increasing, therefore, their vulnerability. Furthermore, following the damage caused by earthquakes in Spain, it has been observed that there are significant differences in the spatial distribution of damage from site to site in buildings with similar seismic behavior, located in a similar site. Hence, many authors have stated that the main factor responsible for the different damage distribution could be the building height. The seismic response of a building depends on its dynamic characteristics (fundamental period, T, damping ratio, ξ, and modal shape) and on the input ground motion. Among the existing methods to determine the T and ξ parameters, the best ones probably are to record weak earthquakes (or near explosions) or induced vibrations inside the building. However, both techniques need a very expensive and time-consuming effort when it is applied to a large number of buildings. A possible alternative is the measurement of ambient vibrations. In this work, ambient vibration measurements were performed at the geometrical center of the plan on the top floor of buildings with different height and year of construction in the municipality of Alicante and Elche (both in the Alicante province), assuming that this point coincides with the mass center of the floor. The preliminary results follow a linear relationship between the number of stories and the fundamental period. Finally, the results have been used to estimate the probability of resonance in several districts of both municipalities.
Structural damage computation using analytical methods requires the knowledge of the ground motion distribution in the urban area caused by a given earthquake. In this manuscript, the ground motion estimates (i.e. PGA and spectral acceleration values) are obtained through simulation of the 1829 Torrevieja earthquake using the NGA ground motion prediction equations (GMPE). The building stock under consideration has been classified according to the methodology presented in RISK-UE. The computations have been done using the last version of the software SELENA. The epistemic uncertainties of the analysis are accounted for by means of a logic tree computation scheme. The logic tree has two branches for the uncertainty in the earthquake scenario, two branches for the GMPEs and three branches to consider the uncertainties in average shear wave velocity Vs30 (soil conditions). Results indicate large differences derived for the different earthquake loss scenarios (ELE) obtained following each branch of the logic tree.The greatest structural damages and losses are obtained when the earthquake is located in the Bajo Segura fault zone, using Campbell and Bozorgnia GMPE and for soft soil conditions. This article has allowed us to see how the different possible input parameters for ELE should be carefully analyzed for each case study and the importance of providing ELE results in terms of mean values with corresponding uncertainty ranges.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.