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Since the early twenty-first century, tall building construction has gained significant momentum in the urban cities of Turkey as a result of the population and economic growth. Accruing more than 1500 buildings by year 2015, the majority of the country's exposure now clusters across the seismically active landscape of the Istanbul metropolitan area. As such, the underlying earthquake risk calls for the investigation of the seismic performance of these structures. While hazard studies for Istanbul are available, the literature is still devoid of studies related to the seismic risk assessment of tall buildings located there. As an attempt to fill this gap, this paper focuses on the characterization and quantification of the existing exposure to allow risk assessment both at single building and portfolio levels. To this end, an extensive tall building inventory containing the structural drawings of 94 buildings is compiled and thoroughly examined to make a projection of the design practice. After establishing statistically representative archetypes, we quantified their dynamic response to 1999 Düzce and Kocaeli earthquake ground motions. We notice a maximum difference of 100% in the maximum interstory drift ratios (equaling a 2% increase in absolute value) between two different tall building archetypes. Moreover, the analysis results indicate that the incident angle of the applied ground-motion can be a discriminant factor between structural collapse and survival. The outcome of this study puts forward a robust basis for prospective structural analyses, collapse risk assessment as well as loss estimation analyses of tall buildings in Istanbul. [ABSTRACT FROM AUTHOR]

This paper focuses on the exposure and fragility/vulnerability of the residential, mixed residential/commercial, and public building stock of the city of Isfahan, in Central Iran, and constitutes the first part of a seismic risk assessment study for that city. To determine the assets at risk, we first summarize the details of the building stock and population from the available georeferenced 2011 Census data. From this dataset and from a local survey of the city, we categorize the building taxonomy in 27 construction classes characterized by age, height, and material/lateral-load-resisting system. A building exposure model is then assembled by first dividing Isfahan in city blocks and then by assigning the appropriate statistical properties to the buildings, such as construction class, built area, and replacement cost. The population of each city block is also estimated and accounted for. To assess the fragility and vulnerability to earthquake ground motion, for each building class we performed nonlinear dynamic analysis of multiple equivalent single-degree-of-freedom systems. This process generated a set of class- and region-specific fragility and vulnerability functions that considered both record-to-record and building-to-building response variability. In the companion paper we used the exposure model and the fragility and vulnerability curves generated for all these asset classes to probabilistically assess the seismic risk of Isfahan. [ABSTRACT FROM AUTHOR]

The second part of a seismic risk assessment study for the Iranian city of Isfahan is presented, focusing on the description of the hazard, the risk analysis, and the discussion of the results. This study utilizes the building exposure model, the fragility and the vulnerability curves illustrated in the companion paper. The earthquake occurrence source model adopted is based on the EMME14 hazard study. The site effects accounting for the soil nonlinear behavior are modeled by means of a Vs30 map derived from the topographical slope. The validity of this map is tested based on the local surface geology and geotechnical reports. The probabilistic seismic hazard maps for different return periods that account for site effects are generated and compared with the design spectra mandated by the Iranian national seismic design code. In addition, direct seismic monetary and human losses are estimated for two earthquake scenarios and also for 100- and 475-year return periods. We show loss maps and loss curves, offering insights on the most vulnerable building classes and the spatial distribution of the estimated losses. The results provide a basis for pre- and post-disaster emergency planning, for global and local urban planning, as well as for conceiving adequate risk mitigation strategies including devising fair earthquake insurance policies. This study may also serve as a blueprint for carrying out similar work in other urban areas of the Middle East. [ABSTRACT FROM AUTHOR]