Though almost thirty years have passed since the 1991 Tunnel Fire, the wildfire hazard is still present in the Oakland Hills. This study was conducted to determine if the vegetation in the Oakland Hills had reverted back to fuel conditions that contributed to the Tunnel Fire, examine how the fire hazard has changed since 1991, and evaluate planned wildfire mitigation. The goal was to determine how fuel conditions have changed since 1991 and compare potential fire behavior to that of the Tunnel Fire. Additionally, the study examined the effectiveness of the mitigation actions described in the East Bay Regional Park District’s Wildfire Hazard Reduction and Resource Management Plan on lowering extreme fire behavior. Through the use of remote sensing, historical aerial imagery, satellite imagery, and Landsat imagery the 1991 and 2018 fuel conditions were analyzed. ArcGIS Pro and FlamMap 6 were used to compare hectares of fuel and changed in fire behavior between the two year. Mitigation actions were modeled with FlamMap 6 and ArcGIS Pro and fire behavior was compared between untreated conditions and post treatment conditions. The vegetation in the Oakland Hills, in the absence of fire, returned to a mature state, similar to the 1991 conditions. However, there was a reduction in the overall hectares of fuel model 147 in 2018. Modeled fire behavior indicated an overall reduction in extreme fire behavior when comparing 1991 to 2018. This reduction varied on a park level with each park performing differently. When modeled, mitigation was able to lower extreme fire behavior across the landscape but success varied on an individual park basis. In conclusion, should ignition occur presently, under foehn wind conditions, a fire would still exhibit very extreme behavior with a high potential for catastrophic loss, and implantation of planned mitigation measures may be able to lower the degree of extreme fire behavior.

Storm surge flooding caused by tropical cyclones is a devastating threat to coastal regions, and this threat is growing due to sea-level rise (SLR). Therefore, accurate and rapid projection of the storm surge hazard is critical for coastal communities. This study focuses on developing a new framework that can rapidly predict storm surges under SLR scenarios for any random synthetic storms of interest and assign a probability to its likelihood. The framework leverages the Joint Probability Method with Response Surfaces (JPM-RS) for probabilistic hazard characterization, a storm surge machine learning model, and a SLR model. The JPM probabilities are based on historical tropical cyclone track observations. The storm surge machine learning model was trained based on high-fidelity storm surge simulations provided by the U.S. Army Corps of Engineers (USACE). The SLR was considered by adding the product of the normalized nonlinearity, arising from surge-SLR interaction, and the sea-level change from 1992 to the target year, where nonlinearities are based on high-fidelity storm surge simulations and subsequent analysis by USACE. In this study, this framework was applied to the Chesapeake Bay region of the U.S. and used to estimate the SLR-adjusted probabilistic tropical cyclone flood hazard in two areas: one is an urban Virginia site, and the other is a rural Maryland site. This new framework has the potential to aid in reducing future coastal storm risks in coastal communities by providing robust and rapid hazard assessment that accounts for future sea-level rise. / Master of Science / Storm surge flooding, which is the rise in sea level caused by tropical cyclones and other storms, is a devastating threat to coastal regions, and its impact is increasing due to sea-level rise (SLR). This poses a considerable risk to communities living near the coast. Therefore, it is crucial to accurately and quickly predict the potential for storm surge flooding. This study aimed to develop a new way that can rapidly estimate peak storm surges under different sea-level rise scenarios for any random synthetic storms of interest and assess the likelihood of their occurrence. The approach is based on historical tropical cyclone datasets and a machine learning model trained on high-quality simulations provided by the US Army Corps of Engineers (USACE). The study focused on the Chesapeake Bay area of the US and estimated the probabilistic tropical cyclone flood hazard in two locations, an urban site in Virginia and a rural site in Maryland. This new approach has the potential to assist in reducing coastal storm risks in vulnerable communities by providing a quick and reliable assessment of the hazard that takes into account the effects of future sea-level rise.

Nitrogen-, sulfur-, and oxygen-substituted heterocyclic polyaromatic hydrocarbons (heterocyclic PAHs) are ubiquitous in all environmental compartments, often co-occurring with their unsubstituted carbocyclic analogues. However, they have received little attention in the hazard assessment of contaminated sites and little is known about their fate and impacts. Due to their higher polarity resulting from the presence of electronegative atoms possessing lone electron pairs, most heterocycles are expected to be less toxic and bioaccumulative than their homocyclic counterparts, which is perhaps why research on their hazard and fate is much more limited. If this assumption is not true (e.g., because factors other than polarity/hydrophobicity drive their hazard), this may lead to an underestimation of the risks posed by contaminated sites or emissions. Therefore, the main objectives of this thesis are (1) to improve the understanding of the physicochemical properties, biodegradability, ecotoxicity, bioaccumulation, and mobility of these compounds in environmental contexts, (2) to evaluate the effectiveness of different modeling approaches in accurately predicting their properties, and (3) to tackle experimental barriers by designing robust techniques that can produce reliable and reproducible data output in the long run. From the large family of heterocycles, structurally comparable representative compounds with log KOW values (as a measure of hydrophobicity) ranging over four orders of magnitude were selected as model structures. First, the most environmentally relevant physicochemical properties of heterocyclic PAHs were investigated, including water solubility (SW), n-octanol-water partition coefficient (KOW), and organic carbon-water partition coefficient (KOC). The effect of molecular size, type and number of heteroatoms on the solubility and partition coefficients was investigated. These properties were then used to test the performance of in silico models, including Quantitative Structure-Property Relationship (QSPR), Polyparameter Linear Free Energy Relationship (pp-LFER), and Conductor-like Screening Model for Realistic Solvation (COSMO-RS), that predict these properties. A screening-level environmental hazard assessment was performed by integrating the data and evidence from multiple sources. The screening results revealed (i) high hazard for 4- and 5-ring compounds mainly due to high persistence and bioaccumulation potential, (ii) limited availability of experimental data, and (iii) notable uncertainty due to the limited applicability domain of the models, stressing the urgent need for a detailed hazard assessment for this group of compounds. The persistence of heterocyclic PAHs in the environment was assessed experimentally through a series of biodegradation tests under aerobic conditions. These included ultimate biodegradation, primary biodegradation and inoculum toxicity tests at different exposure concentrations. None of the test substances (≥3 rings) were found to be readily biodegradable. Therefore, to stimulate the biodegradation process, the microbial community from a wastewater treatment plant was adapted to a mixture of heterocyclic PAHs and biodegradation tests were performed with either adapted or non-adapted bacteria. Surprisingly, there were trade-offs in bacterial adaptation: a positive outcome (degradation of carbazole) is accompanied by a less desirable outcome (increased sensitivity to toxic effects of benzo[c]carbazole). Four of the compounds were identified as primarily biodegradable, while five compounds showed no evidence of biodegradation in any of the tests, indicating a high potential for environmental persistence. Predictions from mathematical models were also compared with measured results and it was found that the models were only partially successful in predicting the degradation timeframe of the heterocycles tested. Furthermore, the short-term acute aquatic toxicity of heterocyclic PAHs was investigated using three surrogate species from different trophic levels of the aquatic food web, including bacteria (Aliivibrio fischeri), unicellular algae (Raphidocelis subcapitata), and water fleas (Daphnia magna). In order to maintain a stable exposure and to avoid loss of concentration caused mainly due to sorption, the passive dosing method was adapted to routine test protocols. Most of the compounds were identified as highly toxic to the tested organisms, and non-polar narcosis (baseline toxicity) was found to be the most likely mode of toxic action for the tested chemicals. Membrane-water partition coefficients (KMW) of heterocyclic PAHs were also determined by solid-supported lipid membrane binding experiments and modeling. The measured KMW values were closely aligned with the KOW values, suggesting that both may be good descriptors for predicting the baseline toxicity and bioaccumulation potential of the tested heterocyclic PAHs. Lastly, the long-term chronic reproductive toxicity and bioaccumulation of large heterocyclic PAHs were investigated using Daphnia magna as an aquatic model organism. The passive dosing method ensured constant exposure even at very low concentration levels (70 ng L-1 to 68 µg L-1) in large and complex experimental systems. Given the enormous time and effort required to conduct long-term toxicity tests with minimal data output, a method was developed to assess chronic toxicity and bioaccumulation potential in a single test. All four substances tested were highly toxic and bioaccumulative in Daphnia magna. However, daphnids’ fecundity recovered rapidly from the toxic effects of the heterocycles during the depuration period in the absence of chemicals. The Predicted No Effect Concentrations (PNECs) of the test compounds were also estimated from the chronic toxicity data and ranged from 1 to 150 ng L-1 in a freshwater environment. Due to the lack of regulation and attention to these compounds, no systematic environmental monitoring data are available for their concentrations in freshwater. However, environmental concentrations of heterocyclic PAHs appear to be higher than the PNECs, particularly at contaminated sites. Thus, the tested heterocycles are of high concern in terms of risks to ecosystems and human health. Overall, the results of this research not only contribute to a comprehensive understanding and progress in the environmental hazard assessment of heterocyclic PAHs, but also present several methodological advances that can be applied to future testing of other challenging substances commonly referred to as 'difficult-to-test'. / Stickstoff-, schwefel- und sauerstoffsubstituierte heterocyclische polyaromatische Kohlenwasserstoffe (heterocyclische PAK) sind in allen Umweltkompartimenten gegenwärtig und treten häufig zusammen mit ihren homocyclischen Analoga auf. Bei der Gefährdungsbeurteilung kontaminierter Standorte wurde ihnen bisher verhältnismäßig wenig Aufmerksamkeit geschenkt, zudem ist über ihr Verhalten und ihre Ökotoxizität nur wenig bekannt. Aufgrund ihrer höheren Polarität, die auf das Vorhandensein elektronegativer Atome zurückzuführen ist, ging man bislang davon aus, dass die meisten heterocyclischen PAK mobiler und weniger toxisch sind als ihre homocyclischen Pendants, weshalb sie wahrscheinlich bislang vergleichsweise wenig studiert wurden. Sollte die Annahme einer geringeren Toxizität nicht zutreffen, weil beispielsweise andere Mechanismen als die Polarität/Hydrophobie für ihre Gefährdung verantwortlich sind, könnte dies zu einer Unterschätzung der Risiken, die von kontaminierten Standorten oder anderen Emissionen ausgehen, führen. Die Hauptziele dieser Arbeit bestehen daher darin, (1) ein umfassenderes Verständnis der physikalisch-chemischen Eigenschaften, der biologischen Abbaubarkeit, der Ökotoxizität, der Bioakkumulation und der Mobilität dieser Verbindungen in der Umwelt zu erlangen; (2) eine Bewertung verschiedener Modellierungsansätze zur Vorhersage dieser Eigenschaften durchzuführen und (3) experimentelle Hindernisse zu überwinden, indem robustere Techniken entwickelt werden, die langfristig zuverlässige und reproduzierbare Daten liefern können. Aus der sehr breiten Gruppe der heterocyclischen Verbindungen wurden strukturell vergleichbare repräsentative Verbindungen mit unterschiedlichen log KOW-Werten (als Maß für die Hydrophobie), die vier Größenordnungen abdecken, als Modellstrukturen ausgewählt. Zunächst erfolgte eine Untersuchung umweltrelevanter physikalisch-chemischer Eigenschaften dieser heterocyclischen PAK, wie die Wasserlöslichkeit (SW), der n-Octanol-Wasser-Verteilungskoeffizient (KOW) und der Verteilungskoeffizient bezogen auf den organischen Kohlenstoff und Wasser (KOC). Dabei wurden die Auswirkungen von Molekülgröße, Art und Anzahl der Heteroatome auf die Löslichkeit und die Verteilungskoeffizienten systematisch untersucht. Diese experimentell ermittelten Parameter wurden dann verwendet, um die Leistung von In-silico-Modellen zu testen, einschließlich der quantitativen Struktur-Eigenschafts-Beziehung (QSPR), der linearen Polyparameter-Energie-Beziehung (pp-LFER) und des Conductor-like Screening Model for Realistic Solvation (COSMO-RS), die diese Eigenschaften vorhersagen. Zudem wurde eine Umweltverträglichkeitsprüfung auf Screening-Ebene durchgeführt, bei der Daten aus verschiedenen Quellen berücksichtigt wurden. Den Screening-Ergebnissen zufolge ist davon auszugehen, dass kleine Verbindungen mit zwei oder drei Ringen in der Umwelt mobil sind, während größere heterocyclische PAK im Allgemeinen als bioakkumulierbare Stoffe identifiziert wurden, was auf ein erhebliches Gefahrenpotenzial hinweist. Die Persistenz von heterocyclischen PAK wurde experimentell durch eine Reihe von Tests zum biologischen Abbau unter aeroben Bedingungen untersucht. Dazu gehörten Tests zur Mineralisierung, zum biologischen Primärabbau und zur Inokulumtoxizität bei unterschiedlichen Expositionskonzentrationen. Keine der Prüfsubstanzen mit drei oder mehr Kohlenstoffringen erwies sich als biologisch gut/schnell abbaubar. Um den biologischen Abbauprozess zu stimulieren, wurde daher die mikrobielle Gemeinschaft aus einer Kläranlage an das Gemisch heterocyclischer PAK angepasst, wobei die Tests zum biologischen Abbau entweder mit angepassten oder nicht angepassten Bakterien durchgeführt wurden. Überraschenderweise gab es bei der bakteriellen Anpassung Widersprüche: positive Effekte (wie der bessere Abbau von Carbazol) gehen mit weniger wünschenswerten Ergebnissen (erhöhte Toxizität gegenüber Benzo[c]carbazol) einher. Für vier der betrachteten Verbindungen wurde ein biologischer Primärabbau festgestellt, während fünf Substanzen in keinem der Tests Anzeichen für eine mikrobielle Umsetzung zeigten, was auf ein hohes Potenzial für eine Persistenz in der Umwelt hindeutet. Die Vorhersagen softwaregestützter Modelle wurden ebenfalls mit den Messergebnissen verglichen, und es zeigte sich, dass die Modelle bei der Vorhersage der Abbaukinetik der getesteten Heterocyclen nur teilweise übereinstimmende Ergebnisse lieferten. Darüber hinaus wurde die akute Kurzzeittoxizität heterocyclischer PAK anhand von drei Arten aus verschiedenen trophischen Ebenen des aquatischen Nahrungsnetzes untersucht: Bakterien (Aliivibrio fischeri), einzellige Algen (Raphidocelis subcapitata) und Wasserflöhe (Daphnia magna). Um eine stabile Exposition aufrechtzuerhalten und Verluste, zum Beispiel durch Sorption an Gefäßwandungen, zu vermeiden, wurde die Methode des „passive dosing“ an Routinetestprotokolle angepasst. Die meisten Verbindungen wurden in diesen Tests als hochgiftig für die getesteten Organismen identifiziert, wobei festgestellt werden konnte, dass unpolare Narkose (Basistoxizität) die wahrscheinlichste Art der toxischen Wirkung der getesteten Chemikalien ist. Darüber hinaus wurden die Membran-Wasser-Verteilungskoeffizienten (KMW) der heterocyclischen PAK durch Lipidmembran-Bindungsexperimente auf festem Trägermaterial sowie mit Hilfe von Vorausberechnungen (Modellierung) bestimmt. Die gemessenen KMW-Werte stimmten eng mit den KOW-Werten überein, was darauf hindeutet, dass beide Werte gute Deskriptoren für die Vorhersage der Basistoxizität bzw. des Bioakkumulationspotenzials der getesteten heterocyclischen PAK sein können. Schließlich wurden die langfristige chronische Reproduktionstoxizität und die Bioakkumulation großer heterocyclischer PAK mit Daphnia magna als aquatischer Modellorganismus untersucht. Die „passive dosing method“ gewährleistete eine konstante Exposition selbst bei sehr niedrigen Konzentrationen (70 ng L-1 bis 68 µg L-1) in groß angelegten und komplexen Versuchssystemen. Angesichts des enormen Zeit- und Arbeitsaufwands, der für die Durchführung von Langzeit-Toxizitätstests erforderlich ist, wurde eine Methode entwickelt, um die chronische Toxizität sowie das Bioakkumulationspotenzial in einem einzigen Test zu bewerten. Alle vier getesteten Substanzen waren gegenüber Daphnia magna hochtoxisch und stark bioakkumulierend. Unerwarteterweise erholte sich die Reproduktionsfähigkeit der Daphnien jedoch schnell von den toxischen Wirkungen der Heterocyclen, wenn die Chemikalienexposition endete. Die PNECs (Predicted No Effect Concentrations) der Testsubstanzen wurden ebenfalls anhand der Daten zur chronischen Toxizität verglichen. Die Werte lagen in einer Süßwasserumgebung zwischen 1 und 150 ng L-1 (PNEC). Für die meisten Testverbindungen gibt es keine Informationen zu Monitoringdaten in der Umwelt. Die Umweltkonzentrationen heterocyclischer PAK scheinen jedoch höher zu sein als die PNEC-Werte, insbesondere an kontaminierten Standorten, was eine Gefahr für die Ökosysteme und die menschliche Gesundheit darstellt. Insgesamt tragen die Ergebnisse dieser Forschungsarbeit nicht nur zu einem umfassenderen Verständnis und zu Fortschritten bei der Bewertung der von heterocyclischen PAK ausgehenden Umweltgefahren bei, sondern liefern auch mehrere methodische Verbesserungen, die in Zukunft bei der Prüfung anderer Stoffe, die gemeinhin als 'schwierig zu testen' bezeichnet werden, angewendet werden können.

No description available.

According to the REACH regulation chemicals produced or imported to the European Union need to be assessed to manage the risk of potential hazard to human health and the environment. An increasing number of chemicals in commerce prompts the need for utilizing faster and cheaper alternative methods for this assessment, such as quantitative structure-activity or property relationships (QSARs or QSPRs). QSARs and QSPRs are models that seek correlation between data on chemicals molecular structure and a specific activity or property, such as environmental fate characteristics and (eco)toxicological effects. The aim of this thesis was to evaluate and develop models for the hazard assessment of industrial chemicals and the exposure assessment of pharmaceuticals. In focus were the identification of chemicals potentially demonstrating carcinogenic (C), mutagenic (M), or reprotoxic (R) effects, and endocrine disruption, the importance of metabolism in hazard identification, and the understanding of adsorption of ionisable chemicals to sludge with implications to the fate of pharmaceuticals in waste water treatment plants (WWTPs). Also, issues related to QSARs including consensus modelling, applicability domain, and ionisation of input structures were addressed. The main findings presented herein are as follows: QSARs were successful in identifying almost all carcinogens and most mutagens but worse in predicting chemicals toxic to reproduction. Metabolic activation is a key event in the identification of potentially hazardous chemicals, particularly for chemicals demonstrating estrogen (E) and transthyretin (T) related alterations of the endocrine system, but also for mutagens. The accuracy of currently available metabolism simulators is rather low for industrial chemicals. However, when combined with QSARs, the tool was found useful in identifying chemicals that demonstrated E- and T- related effects in vivo. We recommend using a consensus approach in final judgement about a compound’s toxicity that is to combine QSAR derived data to reach a consensus prediction. That is particularly useful for models based on data of slightly different molecular events or species. QSAR models need to have well-defined applicability domains (AD) to ensure their reliability, which can be reached by e.g. the conformal prediction (CP) method. By providing confidence metrics CP allows a better control over predictive boundaries of QSAR models than other distance-based AD methods. Pharmaceuticals can interact with sewage sludge by different intermolecular forces for which also the ionisation state has an impact. Developed models showed that sorption of neutral and positively-charged pharmaceuticals was mainly hydrophobicity-driven but also impacted by Pi-Pi and dipole-dipole forces. In contrast, negatively-charged molecules predominantly interacted via covalent bonding and ion-ion, ion-dipole, and dipole-dipole forces. Using ionised structures in multivariate modelling of sorption to sludge did not improve the model performance for positively- and negatively charged species but we noted an improvement for neutral chemicals that may be due to a more correct description of zwitterions.   Overall, the results provided insights on the current weaknesses and strengths of QSAR approaches in hazard and exposure assessment of chemicals. QSARs have a great potential to serve as commonly used tools in hazard identification to predict various responses demanded in chemical safety assessment. In combination with other tools they can provide fundaments for integrated testing strategies that gather and generate information about compound’s toxicity and provide insights of its potential hazard. The obtained results also show that QSARs can be utilized for pattern recognition that facilitates a better understanding of phenomena related to fate of chemicals in WWTP. / Enligt kemikalielagstiftningen REACH måste kemikalier som produceras i eller importeras till Europeiska unionen riskbedömas avseende hälso- och miljöfara. Den ökande mängden kemikalier som används i samhället kräver snabbare och billigare alternativa riskbedömningsmetoder, såsom kvantitativa struktur-aktivitets- eller egenskapssamband (QSARs eller QSPRs). QSARs och QSPRs är datamodeller där samband söks korrelationer mellan data för kemikaliers struktur-relaterade egenskaper och t.ex. kemikaliers persistens eller (eko)toxiska effekter. Målet med den här avhandlingen var att utvärdera och utveckla modeller för riskbedömning av industri kemikalier och läkemedel för att studera hur QSARs/QSPRs kan förbättra riskbedömningsprocessen. Fokus i avhandlingen var utveckling av metoder för identifiering av potentiellt cancerframkallande (C), mutagena (M), eller reproduktionstoxiska (R) kemikalier, och endokrint aktiva kemikalier, att studera betydelsen av metabolism vid riskbedömning och att öka vår förståelse för joniserbara kemikaliers adsorption till avloppsslam. Avhandlingen behandlar även konsensusmodellering, beskrivning av modellers giltighet och betydelsen av jonisering för kemiska deskriptorer. De huvudsakliga resultaten som presenteras i avhandlingen är: QSAR-modeller identifierade nästan alla cancerframkallande ämnen och de flesta mutagener men var sämre på att identifiera reproduktionstoxiska kemikalier. Metabolisk aktivering är av stor betydelse vid identifikationen av potentiellt toxiska kemikalier, speciellt för kemikalier som påvisar östrogen- (E) och sköldkörtel-relaterade (T) förändringar av det endokrina systemet men även för mutagener. Träffsäkerheten för de tillgängliga metabolismsimulatorerna är ganska låg för industriella kemikalier men i kombination med QSARs så var verktyget användbart för identifikation av kemikalier som påvisade E- och T-relaterade effekter in vivo. Vi rekommenderar att använda konsensusmodellering vid in silico baserad bedömning av kemikaliers toxicitet, d.v.s. att skapa en sammanvägd förutsägelse baserat på flera QSAR-modeller. Det är speciellt användbart för modeller som baseras på data från delvis olika mekanismer eller arter. QSAR-modeller måste ha ett väldefinierat giltighetsområde (AD) för att garantera dess pålitlighet vilket kan uppnås med t.ex. conformal prediction (CP)-metoden. CP-metoden ger en bättre kontroll över prediktiva gränser hos QSAR-modeller än andra distansbaserade AD-metoder. Läkemedel kan interagera med avloppsslam genom olika intermolekylära krafter som även påverkas av joniseringstillståndet. Modellerna visade att adsorptionen av neutrala och positivt laddade läkemedel var huvudsakligen hydrofobicitetsdrivna men också påverkade av Pi-Pi- och dipol-dipol-krafter. Negativt laddade molekyler interagerade huvudsakligen med slam via kovalent bindning och jon-jon-, jon-dipol-, och dipol-dipol-krafter. Kemiska deskriptorer baserade på joniserade molekyler förbättrade inte prestandan för adsorptionsmodeller för positiva och negativa joner men vi noterade en förbättring av modeller för neutrala substanser som kan bero på en mer korrekt beskrivning av zwitterjoner. Sammanfattningsvis visade resultaten på QSAR-modellers styrkor och svagheter för användning som verkyg vid risk- och exponeringsbedömning av kemikalier. QSARs har stor potential för bred användning vid riskidentifiering och för att förutsäga en mängd olika responser som krävs vid riskbedömning av kemikalier. I kombination med andra verktyg kan QSARs förse oss med data för användning vid integrerade bedömningar där data sammanvägs från olika metoder. De erhållna resultaten visar också att QSARs kan användas för att bedöma och ge en bättre förståelse för kemikaliers öde i vattenreningsverk.

The object of this diploma thesis is to perform Functional Hazard Assessment of small four-seat aircraft according to Federal Aviation Regulations Part 23, which would be similar to present aircrafts on market. Input data were acquired by research of systems aircrafts use on current market. On this basis the Functional Hazard Assessment was performed ad aircraft level. Total loss of power supply was qualified as Catastrophic therefore is used in following assessment. A preliminary failure rate assessment of typical parts used in electrical system was performed at the end of diploma thesis. For the most crucial parts a simple model was created and failure rate computed.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23182号 / 工博第4826号 / 新制||工||1754(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 米田 稔, 教授 高野 裕久, 教授 松井 康人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・論文博士 / 博士(工学) / 乙第13173号 / 論工博第4164号 / 新制||工||1699(附属図書館) / (主査)教授 寶 馨, 教授 渦岡 良介, 准教授 佐山 敬洋 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

A topology-based approach has been used to measure the resilience of a highway network to climatic events. Civil infrastructure systems are inarguably critical to the everyday functions of society. Because such systems are regionally distributed, their components undergo a wide range of hazard intensities, often dependent on their relative locations. The ability of an infrastructure system to withstand, adapt to, and rapidly recover from extreme events is paramount to its ability to continuously serve users. The topological properties of a network can provide a good means to assess the resilience of the system which is adequate to comprehend the preparedness and functionality of an infrastructure system in the face of various hazards. Hurricanes and storm surges are especially relevant on the eastern coast of the US, where they can cause widespread damage and destruction. Furthermore, the effects of climate change are proven to increase the intensity of climatic events, worsening the consequences to infrastructure networks. The vulnerability of the transportation network of New York City, the most populous urban area in the U.S., was underlined in the aftermath of Hurricane Sandy, and for this purpose has been chosen as the test bed for this study. Reducing the highway system to a combination of nodes and links, the principles of graph theory are applied to quantify defining network properties. More specifically, by assessing and measuring the change in topological properties during extreme climatic events, the resilience of a transportation network can be succinctly evaluated.

The objective of this study is to evaluate the regional differences between the worldwide based NGA-W1 ground motion models and available Turkish strong ground motion dataset and make the required adjustments in the NGA-W1 models. A strong motion dataset using parameters consistent with the NGA ground motion models is developed by including strong motion data from Turkey. Average horizontal component ground motion is computed for response spectral values at all available periods using the GMRotI50 definition consistent with the NGA-W1 models. A random-effects regression with a constant term only is used to evaluate the systematic differences in the average level of shaking. Plots of residuals are used to evaluate the differences in the magnitude, distance, and site amplification scaling between the Turkish dataset and the NGA-W1 models. Model residuals indicated that the ground motions are overestimated by all 5 NGA-W1 models significantly, especially for small-to-moderate magnitude earthquakes. Model residuals relative to distance measures plots suggest that NGA-W1 models slightly underestimates the ground motions for rupture distances within 100-200 km range. Models including the aftershocks over-predict the ground motions at stiff soil/engineering rock sites. The misfit between the actual data and model predictions are corrected with adjustments functions for each scaling term. Turkey-Adjusted NGA-W1 models proposed in this study are compatible with the Turkish strong ground motion characteristics and preserve the well-constrained features of the global models. Therefore these models are suitable candidates for ground motion characterization and PSHA studies conducted in Turkey.