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The influence of vertical ground motions on the seismic response of highway bridges is not very well understood. Recent studies suggest that vertical ground motions can substantially increase force and moment demands on bridge columns and girders and cannot be overlooked in seismic design of bridge structures. For an evaluation of vertical ground motion effects on the response of single‐bent two‐span highway bridges, a systematic study combining the critical engineering demand parameters (EDPs) and ground motion intensity measures (IMs) is required. Results of a parametric study examining a range of highway bridge configurations subjected to selected sets of horizontal and vertical ground motions are used to determine the structural parameters that are significantly amplified by the vertical excitations. The amplification in these parameters is modeled using simple equations that are functions of horizontal and vertical spectral accelerations at the corresponding horizontal and vertical fundamental periods of the bridge. This paper describes the derivation of seismic demand models developed for typical highway overcrossings by incorporating critical EDPs and combined effects of horizontal and vertical ground motion IMs depending on the type of the parameter and the period of the structure. These models may be used individually as risk‐based design tools to determine the probability of exceeding the critical levels of EDP for pre‐determined levels of ground shaking or may be included explicitly in probabilistic seismic risk assessments. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
3.
The objective of this study is to evaluate the seismic hazard in Eastern Marmara Region using an improved probabilistic seismic hazard assessment methodology. Two significant improvements over the previous seismic hazard assessment practices are accomplished in this study: advanced seismic source characterization models in terms of source geometry and recurrence relationships are developed, and improved global ground motion models (NGA-W1 models) are employed to represent the ground motion variability. Planar fault segments are defined and a composite magnitude distribution model is used for all seismic sources in the region to properly represent the characteristic behavior of the North Anatolian Fault without the need for an additional background zone. Multi-segment ruptures are considered using the rupture model proposed by the Working Group on California Earthquake Probabilities (2003). Events in the earthquake catalogue are attributed to the fault zones and scenario weights are determined by releasing the accumulated seismic energy. The uniform hazard spectra at 10 % probability of exceedance in 50 years hazard level for different soil conditions (soil and rock) are revealed for specific locations in the region (Adapazar?, Düzce, Gemlik, Izmit, Iznik and Sapanca). Hazard maps of the region for rock site conditions at the selected hazard levels are provided to allow the readers perform site-specific hazard assessment and develop site-specific design spectrum for local site conditions. 相似文献
4.
Polycyclic aromatic hydrocarbons (PAHs) are important environmental pollutants due to their persistence and bioaccumulation potential both in organisms and in sediments. In this study, bioaccumulation and depuration experiments were performed employing local Mediterranean mussel species, Mytilus galloprovincialis, with two biomarkers: filtration rate and lysosomal stability (neutral red retention) assay. Benzo(a)anthracene (BaA) was chosen as the model PAH compound due to its common presence in several matrices in the marine environment. Bioconcentration Factors (BCFs) for the mussels exposed to different BaA concentrations were calculated from both kinetic rate constants and from the experimental data and found between 27-3184 and 16-2745, respectively. Experimental QSAR values were found comparable to the previous QSAR models created for BaA. The effect of BaA exposure on the mussels showed a more clear dose-response relationship according to the results of lysosomal stability compared to the filtration rate. 相似文献
5.
Huseyin Ozdemir Alper Unal Tayfun Kindap Ufuk Utku Turuncoglu Zeynep Okay Durmusoglu Maudood Khan Mete Tayanc Mehmet Karaca 《Theoretical and Applied Climatology》2012,108(1-2):31-38
The Anatolian Peninsula is located at the confluence of Europe, Asia, and Africa and houses 81 cities of which 79 of them have population over 100,000. We employed some criteria to select the cities from the 81 cities. After accomplishing all the criteria, eight cities were remaining for the study. Nonparametric Mann–Kendall test procedure was employed for the urban and rural stations of these cities to detect the long-term change in temperature trends. Statistical analysis of daily minimum temperatures for the period between 1965 and 2006 suggest that there is no statistically significant increase in rural areas. In contrast to the findings of the previous studies, however, all the urban sites and difference between urban and rural pairs show significant increase in temperatures, a strong indication for the existence of urban heat island (UHI) affect over the region. Regional Climate Model was also utilized to assess the changes in temperature by the end of century for the region. The findings suggest that an increase of up to 5°C is possible. Climate change effects enforced with UHI have the potential to cause serious problems for the entire region and hence needs to be studied thoroughly. 相似文献
6.
Enis Morkoc Legovic Tarzan Oya Okay Huseyin Tufekci Vildan Tufekci Leyla Tolun Fatma Karakoc 《Environmental Geology》2007,53(1):103-112
The Izmit Bay is an elongated semi-enclosed bay in the Marmara Sea. It is being increasingly polluted by both domestic and
industrial waste discharge since 1970’s. A monitoring program was conducted between 1999-2000 to document the state of pollution
in the bay. This includes the effect of Marmara (Izmit) earthquake (magnitude 7.4) that occurred in August 1999. A stable
two-layer ecosystem exists in the bay throughout the year due to continuous inflows of the saltier Mediterranean and brackish
Black Sea waters to the Marmara basin. Therefore, the principal biochemical characteristics of the bay are governed by the
two-layer flow system over the basin. Dissolved oxygen (DO) is generally at a saturated levels in the surface layer which
is 10 to 15 m thick, but it is depleted to 60–70 μM in the lower layer, exhibiting a steep gradient in the sharp halocline.
When the earthquake occurred, great loads of industrial wastes were released into the bay surface waters, which enhanced primary
production in the upper layer and thus large export of particulate organic matter to lower layer and eventually to the bottom.
Accordingly, DO was consumed and anoxic condition was established even in the upper layer/halocline interface, the halocline
and bottom waters of the eastern and central bay. In this period, concurrent increases were observed in phosphate and ammonia
contents at the halocline and in deep waters whilst the nitrate was almost consumed via denitrification processes in the anoxic
water. Recently, the industrial C, N and P loads increased by as much as 8 fold within five years (1995–2000) whilst domestic
inputs increased by 50%. Total organic matter discharged to the bay increased more than double within the last 15 years. Besides,
most factories in the region release toxic wastes into the bay after only partial treatment. 相似文献
7.
Budakoglu Murat Unluer Ali Tugcan Doner Zeynep Kocaturk Huseyin Kaya Mustafa Kumral Mustafa Kirikoglu M. Sezai 《中国地球化学学报》2021,40(6):926-944
Acta Geochimica - In the last five decades, Rare Earth Elements (REE) are mostly produced from carbonatite complexes and alkaline magmatic environments. In this respect, pyroclastic flows produced... 相似文献
8.
A. I. Okay 《Journal of Metamorphic Geology》2002,20(8):757-768
Sodic metapelites with jadeite, chloritoid, glaucophane and lawsonite form a coherent regional metamorphic sequence, several tens of square kilometres in size, and over a kilometre thick, in the Orhaneli region of northwest Turkey. The low‐variance mineral assemblage in the sodic metapelites is quartz + phengite + jadeite + glaucophane + chloritoid + lawsonite. The associated metabasites are characterized by sodic amphibole + lawsonite ± garnet paragenesis. The stable coexistence of jadeite + chloritoid + glaucophane + lawsonite, not reported before, indicates metamorphic pressures of 24 ± 3 kbar and temperatures of 430 ± 30 °C for the peak blueschist facies conditions. These P–T conditions correspond to a geotherm of 5 °C km?1, one of the lowest recorded in continental crustal rocks. The low geotherm, and the known rate of convergence during the Cretaceous subduction suggest low shear stresses at the top of the downgoing continental slab. 相似文献
9.
Zeynep Clulow 《Climate Policy》2018,18(2):221-234
Is economic development compatible with mitigation? On the one hand, development should promote effective climate policy by enhancing states’ capacities for mitigation. On the other hand, economic growth creates more demand for production, thereby inhibiting emissions reduction. These arguments are often reconciled in the environmental Kuznets curve (EKC) thesis. According to this approach, development initially increases emissions in poor economies, but begins to lower emissions after a country has attained a certain level of development.The aim of this article is to determine empirically whether the EKC hypothesis seems plausible in light of emissions trends over the birth and implementation of the Kyoto Protocol. Drawing on data from the World Bank World Development Indicators and World Resources Institute Climate Data Explorer, it conducts a large-N investigation of the emissions behaviour of 120 countries from 1990 to 2012. While several quantitative studies have found that economic factors influence emissions activity, this article goes beyond existing research by employing a more sophisticated – multilevel – research design to determine whether economic development: (a) continues to be a significant driver once country-level clustering is accounted for and (b) has different effects on different countries. The results of this article indicate that, even after we account for country-level clustering and hold constant the other main putative drivers of emissions activity, economic development tends to inhibit emissions reduction. They also provide strong evidence that emissions trends resemble the EKC, with development significantly constraining emissions reduction in the South and promoting it in the North.POLICY RELEVANCEThis article contributes to the understanding of the (changing) role of economic development in shaping emissions activity. It demonstrates the need for a contextualized, country-specific approach for evaluating the effectiveness of economic development in promoting emissions reduction and uncovers new evidence in support of the EKC hypothesis. 相似文献
10.
Natural Hazards - Consequences of urban floods increased and diversified in terms of social, economical and environmental effects, due to the dense and unplanned urbanization in areas at risk of... 相似文献