Summary
Pulse‐like records are well recognized for their potential to impose higher demands on structures when compared with ordinary records. The increased severity of the structural response ...usually caused by pulse‐like records is commonly attributed to the spectral increment around the pulse period. By comparing the building response to sets of spectrally equivalent pulse‐like and ordinary records, we show that there are characteristics of pulse‐like records beyond the shape of the acceleration response spectrum that affect the results of nonlinear dynamic analysis. Nevertheless, spectral shape together with the ratio of pulse period to the first‐mode structural period, Tp/T1, are confirmed as “sufficient” predictors for deformation and acceleration response metrics in a building, conditioned on the seismic intensity. Furthermore, the average spectral acceleration over a period range, AvgSA, is shown to incorporate to a good proxy for spectral shape, and together with Tp/T1, form an efficient and sufficient intensity measure for response prediction to pulse‐like ground motions. Following this latter route, we propose a record selection scheme that maintains the consistency of Tp with the hazard of the site but uses AvgSA to account for the response sensitivity to spectral shape.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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
Vs
30
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.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Average spectral acceleration,
AvgSA
, is defined as the geometric mean of spectral acceleration values over a range of periods and it is a ground motion intensity measure used for structural ...response prediction. One of its advantages stands on the assumption that its distribution is computable from the available GMPEs for spectral acceleration, GMPE-
SA
, (called here
indirect
method) without the need for deriving new specific GMPEs for
AvgSA
, GMPE-
AvgSA,
(called here
direct
method). To what extent this assumption is valid, however, has never been verified. As such, we derived an empirical GMPE-
AvgSA
based on RESORCE ground motion dataset and we compared its predicted values with those from a GMPE-
SA
via the indirect approach. As expected, the results show that the indirect approach yields median
AvgSA
estimates that are identical to those of the direct approach. However, the estimates of
AvgSA
variance of the two methods are identical only if both the GMPE-
SA
and their empirical correlation coefficients among different
SA
ordinates are derived from the same record dataset.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study applies the latest probabilistic performance-based earthquake engineering tools in terms of nonlinear dynamic analyses in tandem with hazard-consistent record selection to assess the risk ...of collapse of RC tall buildings in the Istanbul metropolitan area and to quantify their seismic safety margin with respect to acceptable risk levels. Statistically representative archetype buildings selected from an extensive inventory form the basis for this assessment study. Accordingly, we chose five hypothetical building sites in Istanbul where tall buildings are densely populated to estimate the risk of collapse for 5 × 5 = 25 building-and-site specific cases. The results showed an average 10% probability of collapse under the ground-motion intensities with 2% probability of exceedance in 50 years. The mean annual rates of collapse range between 0.1 × 10
–4
and 6.1 × 10
–4
with an average of 1.7 × 10
–4
, which remains below the tolerable risk threshold value of 2.0 × 10
–4
envisioned by the FEMA’s Building Seismic Safety Council. However, 36% of the analyzed cases yielded collapse rates higher than this tolerable risk. Among the considered cases, the
core walls and frame
building was identified as the best design choice from a collapse safety point of view while the
tunnel form
archetype raised concern by exhibiting substantially higher collapse risk compared to other archetypes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Automated Multi-Depth Shuttle Warehouses (AMSWs) are compact storage systems that provide a large surface occupation and therefore maximum storage density. AMSWs represent the future of storage ...technology, providing substantial savings in terms of cost, space, and energy with respect to traditional warehouses. Currently, designers refer to the standard building codes for the seismic design of AMSWs. Since structural characteristics of AMSWs are considerably different from the steel structures of typical buildings, this current approach used by designers is questionable in terms of safety and efficiency. In this article, the behavior of 5 AMSW structures has been studied performing 150 time-history analyses by direct integration including P-Delta effects. Demand/capacity ratios calculated for each element showed the dominance of the brittle failure mechanism in AMSWs subjected to low-to-moderate seismic actions. These mechanisms mainly took place in upright columns and their base connections prior to the activation of ductile energy dissipation mechanisms of the structure. Based on the results, further improvements have been recommended for the future design provisions, which may lead to a safer seismic design of AMSWs.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The influence of the effects of the degradation of materials on the seismic fragility of Cultural Heritage buildings in Granada (Spain) is investigated. The degradation of the material, which mainly ...happens at the lower levels of the façades, is obtained by using 3D photogrammetry data. Fragility curves for three cultural heritage constructions in Granada are calculated by using FE nonlinear dynamic analyses for both non-deteriorated and deteriorated geometries. The Finite Elements (FE) models, based on the macro-modelling technique, are subjected to ground motions for the city of Granada, which were selected by considering Probabilistic Seismic Hazard Analysis (PSHA) methodology with their probability of occurrence. The response of each model is analyzed for different seismic Intensity Measure (IM) levels, which, in this study, correspond to average pseudo-acceleration. The procedure is applied to three monuments in Granada that were built with two different constructions materials: calcarenite and rammed earth. The damage mechanisms considered are roof displacement or maximum compressive principal stress, depending on each case. The results show that the restoration works that have been carried out has prevented structural failures in the rammed earth construction studied, and that, during future seismic events, special attention must be paid to the level of compressive strengh reached in the Santa Pudia calcarenite used at the San Jerónimo monastery.
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