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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
701

Earthquake Characteristics as Imaged by the Back-Projection Method

Kiser, Eric January 2012 (has links)
This dissertation explores the capability of dense seismic array data for imaging the rupture properties of earthquake sources using a method known as back-projection. Only within the past 10 or 15 years has implementation of the method become feasible through the development of large aperture seismic arrays such as the High Sensitivity Seismograph Network in Japan and the Transportable Array in the United States. Coincidentally, this buildup in data coverage has also been accompanied by a global cluster of giant earthquakes (Mw>8.0). Much of the material in this thesis is devoted to imaging the source complexity of these large events. In particular, evidence for rupture segmentation, dynamic triggering, and frequency dependent energy release is presented. These observations have substantial implications for evaluating the seismic and tsunami hazards of future large earthquakes. In many cases, the details of the large ruptures can only be imaged by the back-projection method through the addition of different data sets and incorporating additional processing steps that enhance low-amplitude signals. These improvements to resolution can also be utilized to study much smaller events. This approach is taken for studying two very different types of earthquakes. First, a global study of the enigmatic intermediate-depth (100-300 km) earthquakes is performed. The results show that these events commonly have sub-horizontal rupture planes and suggest dynamic triggering of multiple sub-events. From these observations, a hypothesis for the generation of intermediate-depth events is proposed. Second, the early aftershock sequences of the 2004 Mw 9.1 Sumatra-Andaman and 2011 Mw 9.0 Tohoku, Japan earthquakes are studied using the back-projection method. These analyses show that many events can be detected that are not in any local or global earthquake catalogues. In particular, the locations of aftershocks in the back-projection results of the 2011 Tohoku sequence fill in gaps in the aftershock distribution of the Japan Meteorological Agency catalogue. These results may change inferences of the behavior of the 2011 mainshock, as well as the nature of future seismicity in this region. In addition, the rupture areas of the largest aftershocks can be determined, and compared to the rupture area of the mainshock. For the Tohoku event, this comparison reveals that the aftershocks contribute significantly to the cumulative failure area of the subduction interface. This result implies that future megathrust events in this region can have larger magnitudes than the 2011 event. / Earth and Planetary Sciences
702

Engaging youth on their own terms? an actor-network theory account of hip-hop in youth work.

Wilson, Elizabeth Kate January 2015 (has links)
With origins in the South Bronx area of New York in the early 1970s, hip-hop culture is now produced and consumed globally. While hip-hop activities can be varied, hip-hop is generally considered to have four forms or “elements”: DJing, MCing, b-boying/b-girling, and graffiti. Although all four elements of hip-hop have become a part of many youth work initiatives across the globe, public debate and controversy continue to surround hip-hop activities. Very little research and literature has explored the complexities involved in the assembling of hip-hop activities in youth work sites of practice using these hip-hop elements. This study attends to the gap in hip-hop and human service literature by tracing how hip-hop activities were assembled in several sites of youth work activity in Christchurch, New Zealand. Actor-network theory (ANT) is the methodological framework used to map the assemblage of hip-hop-youth work activities in this study. ANT follows how action is distributed across both human and non-human actors. By recognising the potential agency of “things”, this research traces the roles played by human actors, such as young people and youth workers, together with those of non-human actors such as funding documents, social media, clothing, and youth venue equipment. This ethnographic study provides rich descriptions or “snapshots” of some of the key socio-material practices that shaped the enactment of hip-hop-youth work activities. These are derived from fieldwork undertaken between October 2009 and December 2011, where participant observation took place across a range of sites of hip-hop-youth work activity. In addition to this fieldwork, formal interviews were undertaken with 22 participants, the majority being youth workers, young people, and youth trust administrators. The ANT framework reveals the complexity of the task of assembling hip-hop in youth work worlds. The thesis traces the work undertaken by both human and non-human actors in generating youth engagement in hip-hop-youth work activities. Young people’s hip-hop interests are shown to be varied, multiple, and continually evolving. It is also shown how generating youth interest in hip-hop-youth work activities involved overcoming young people’s indifference or lack of awareness of the hip-hop resources a youth trust had on offer. Furthermore, the study highlights where hip-hop activities were edited or “tinkered” with to avoid hip-hop “bads”. The thesis also unpacks how needed resources were enlisted, and how funders’ interests were translated into supporting hip-hop groups and activities. By tracing the range of actors mobilised to enact hip-hop-youth work activities, this research reveals how some youth trusts could avoid having to rely on obtaining government funds for their hip-hop activities. The thesis also includes an examination of one youth trust’s efforts to reconfigure its hip-hop activities after the earthquakes that struck Christchurch city in 2010 and 2011. Working both in and on the world, the text that is this thesis is also understood as an intervention. This study constitutes a deliberate attempt to strengthen understandings of hip-hop as a complex, multiple, and fluid entity. It therefore challenges traditional media and literature representations that simplify and thus either stigmatise or celebrate hip-hop. As such, this study opens up possibilities to consider the opportunities, as well as the complexities of assembling hip-hop in youth work sites of practice.
703

Στατική-αντισεισμική μελέτη και σχεδιασμός κτηρίου διοίκησης Ε.Α.Π.

Κάρτσακας, Αλέξανδρος 27 January 2009 (has links)
Η παρούσα διπλωματική εργασία πραγματεύεται την στατική και αντισεισμική μελέτη και σχεδιασμό του Β’ Κτηρίου Διοίκησης Ε.Α.Π. Ο φέροντας οργανισμός του συγκεκριμένου κτηρίου συνίσταται από μεταλλική ανωδομή με σύμμικτες πλάκες και υπόγειο οπλισμένου σκυροδέματος. Η ανάλυση έγινε βάση των αρχών που επιβάλλουν οι Ευρωκώδικες 1, 3, 4 και ο Ελληνικός Κανονισμός Ωπλισμένου Σκυροδέματος (Ε.Κ.Ω.Σ.) καθώς και ο Ελληνικός Αντισεισμικός Κανονισμός (Ε.Α.Κ.). Η ανάλυση έγινε από τα προγράμματα FESPA, που έχει αναπτυχθεί από την εταιρία LH ΛΟΓΙΣΜΙΚΗ, και STRAD, STEEL, που έχουν αναπτυχθεί από την εταιρία 4Μ. Η εργασία αποτελείται από έξι(6) κεφάλαια. Στο πρώτο κεφάλαιο γίνεται μια σύντομη εισαγωγή στο οπλισμένο σκυρόδεμα και τον δομικό χάλυβα. Παρουσιάζονται οι δυνατότητες καθώς και οι αδυναμίες του κάθε υλικού κατασκευής. Επίσης, γίνεται μια συνοπτική περιγραφή της κατασκευής που πρόκειται να αναλυθεί και να διαστασιολογηθεί. Στο δεύτερο κεφάλαιο γίνεται η παρουσίαση των βασικών αρχών των Ευρωκώδικων 1,3,4, του ΕΚΩΣ και του ΕΑΚ σύμφωνα με τις οποίες γίνεται η ανάλυση και διαστασιολόγηση της κατασκευής. Στο τρίτο κεφάλαιο παρουσιάζονται τα προγράμματα FESPA, STRAD και STEEL με τα οποία πραγματοποιείται η ανάλυση και η διαστασιολόγηση της κατασκευής. Παρουσιάζονται κατά σειρά η μέθοδος με την οποία εκτελούν την στατική, αλλά και τη δυναμική-φασματική ανάλυση, οι συμβάσεις αξόνων και μελών, οι έλεγχοι που πραγματοποιούνται κ.α. Στο τέταρτο κεφάλαιο, γίνεται η εύρεση των απαραίτητων για την ανάλυση δεδομένων σύμφωνα με τις αρχές που δίνονται στο κεφάλαιο 2. Κατ’αρχήν παρουσιάζεται το μοντέλο της κατασκευής. Έπειτα, προσδιορίζονται κατασκευαστικά στοιχεία όπως το πάχος πλακών, προσδιορίζονται τα φορτία λόγω ίδιου βάρους, φορτία επικαλύψεων και τοιχοποιίας, ωφέλιμα φορτία, φορτία χιονιού και ανέμου. Καθορίζονται τα φασματικά δεδομένα που απαιτούνται για την δυναμική-φασματική ανάλυση της κατασκευής. Τέλος, γίνεται αναφορά στο τρόπο που έγινε η προσομοίωση και εξιδανίκευση του φορέα και στις παραδοχές που χρειάστηκαν για να γίνει. Στο πέμπτο κεφάλαιο-που ίσως είναι και το ουσιαστικότερο όλων-γίνεται ο έλεγχος και η διαστασιολόγηση της κατασκευής με κάθε πρόγραμμα ξεχωριστά. Συγκεκριμένα γίνεται ο έλεγχος των μελών, από δομικό χάλυβα και από οπλισμένο σκυρόδεμα, σε επίπεδο διατομής και μέλους καθώς και ο αναλυτικός έλεγχος των δυσμενέστερων μελών, γίνονται οι έλεγχοι λειτουργικότητας και παραμορφώσεων (όπως έλεγχος επιρροής φαινομένων δεύτερης τάξης και έλεγχος βλαβών) και τέλος παρουσιάζεται η ανάλυση και η διαστασιολόγηση του υπογείου και της θεμελίωσης. Στο έκτο και τελευταίο κεφάλαιο γίνεται η επίλυση των σύμμικτων πλακών της οροφής ισογείου και της οροφής α’ ορόφου. Συγκεκριμένα γίνεται η επιλογή της γεωμετρίας των σύμμικτων πλακών και ο έλεγχος τους σε κάμψη, εγκάρσια και διαμήκη διάτμηση, λειτουργικότητας και ρηγμάτωσης. Επειδή τα συγκεκριμένα προγράμματα δεν επιλύουν σύμμικτες πλάκες, η επίλυσή τους έγινε στο χέρι και στη συνέχεια τα αποτελέσματα δόθηκαν στα προγράμματα ώστε να γίνει η επίλυση όλου του φορέα. / This project concerns a static-earthquake resistant construction of a building in the University of Patras.
704

Υλοποίηση εικονικών χαρακτήρων σε εκπαιδευτικό εικονικό περιβάλλον

Βλαχώνη, Γεωργία 15 October 2008 (has links)
Η παρούσα διπλωματική εργασία ασχολείται με την κατασκευή ενός εικονικού περιβάλλοντος που αναπαριστά μια σχολική τάξη. Στην εικονική τάξη προστίθενται εικονικοί χαρακτήρες που αποτελούν τους μαθητές της τάξης καθώς επίσης και τη δασκάλα τους. Το σενάριο που ακολουθεί είναι η ενημέρωση των εικονικών μαθητών από τη διδάσκουσα για τους τρόπους αντίδρασης των μαθητών σε περίπτωση σεισμού. / -
705

Μελέτη των περιβαλλοντικών συνθηκών έκλυσης του χημικού στοιχείου 222Rn και η πιθανή συσχέτιση της με την σεισμικότητα της περιοχής Μεγάρων

Οικονομόπουλος, Ευάγγελος 18 March 2009 (has links)
Kατά τις τελευταίες δύο δεκαετίες θεωρείται ότι υπάρχουν ενδείξεις πιθανού συσχετισμού των μεταβολών του εκλυόμενου ραδονίου στο έδαφος και της σεισμικής δραστηριότητας. Παρότι στην Ελλάδα εκδηλώνεται το μεγαλύτερο μέρος της σεισμικής δραστηριότητας της Ευρώπης, δεν έχουν πραγματοποιηθεί συστηματικές έρευνες έως τώρα. Η περιοχή της διατριβής καλύπτει την ανάγκη ανάλυσης της έκλυσης ραδονίου από περιβαλλοντικές παραμέτρους και τη σεισμικότητα. Το πείραμα χωροθετήθηκε στην περιοχή του Κορινθιακού κόλπου λόγω του ότι: 1) παρουσιάζεται υψηλή σεισμικότητα, η σεισμικότητα σε αυτή την περιοχή δε είναι εντοπισμένη σε ένα συγκεκριμένο τμήμα της, αλλά χαρακτηρίζει την ευρύτερη περιοχή. 2) Στην περιοχή εκδηλώνονται συχνά σεισμικά γεγονότα όλων των μεγεθών, σχετιζόμενα με τη σεισμικότητα της ίδιας της περιοχής, αλλά και λόγω διέγερσης σεισμικών ρηγμάτων στην εγγύς περιοχή (π.χ. σεισμοί Αλκυονίδων 1981 και σεισμοί Αθήνας 1999). 3) Η ύπαρξη στην περιοχή ενός μεγάλου αριθμού ρηγμάτων, τα οποία έχουν σαφή επιφανειακή έκφραση. Η ύπαρξη ρηγμάτων με σαφή επιφανειακή έκφραση δίνει επιπλέον τη δυνατότητα μέτρησης της ροής ραδονίου μέσα από ένα ρήγμα. 4) Στην περιοχή μελέτης υπάρχουν καλής ακρίβειας σεισμολογικά και μετεωρολογικά δεδομένα, έτσι ώστε να μπορεί να συσχετισθεί η επίπτωση των μετεωρολογικών αλλαγών με τις μετρήσεις ραδονίου. Η συγκεκριμένη περιοχή δε χαρακτηρίζεται από βίαιες μετεωρολογικές μεταβολές, οι οποίες επηρεάζουν την έκλυση του ραδονίου. / Over the last decades evidence for correlation between radon emission and earthquake activity suggests that monitoring of radon in soil gas can be used as a method to predict future earthquakes. However, although the method is promising for earthquake prediction and most of the seismic activity in Europe is released in Greece, no systematic experiments were conducted so far. In this study we present preliminary results of a two years experiment through the monitoring of eight sites in the Megara basin. In each site, soil radon exhalation was monitored in shallow boreholes (80 cm deep), using CR39 films, which were exposed every 15-day. The Megara basin was selected as a study area for the following reasons: (a) the basin is actively deformed and most of this deformation is accommodated by strong historic earthquakes. The most recent of these events are the 1981 Corinth earthquake sequence. (b) Within the basin large faults have spectacular outcrops, and or still preserve seismic ruptures. Thus the tectonic setting of the monitoring sites is well known in its tectonic position. (c) The entire experiment is set up quite close to Athens, thus earthquake epicenters are calculated fairly well and detailed meteorological data are also available. The experiment includes a series of monitoring sites distributed from Megara town to the coast of the Alkyonides bay, that it well known as the epicenter of the 1981 Corinth earthquakes. In essence the coastal area of the Gulf is rather the surface expression of the South Alkyonides Fault zone. Surface displacement along this fault during the 1981 event reached up to 1 m north side down. Based on these monitoring sites, we present the first results regarding the background soil radon concentration in the Megara basin as well as radon exhalation through a fault. Specifically, we present data of radon exhalation through a still preserved co-seismic rupture, 20 north of the rupture on the hanging wall block and 200 m south of the rupture within the footwall block of the South Alkyonides Fault zone.
706

Design of Controlled Rocking Steel Frames to Limit Higher Mode Effects

Andree Wiebe, Lydell Deighton 14 January 2014 (has links)
Because conventional seismic force resisting systems rely on yielding of key structural members to limit seismic forces, structural damage is expected after a design-level earthquake. Repairing this damage can be very expensive, if it is possible at all. Researchers have been developing a new family of self-centring systems that avoid structural damage. One such system is a controlled rocking steel frame, which is the subject of this thesis. In a controlled rocking steel frame, the columns of a frame are permitted to uplift from the foundation, and the response is controlled by using a combination of post-tensioning and energy dissipation. Although previous studies have confirmed the viability of this system, they have also shown that rocking does not fully limit the peak seismic forces because of higher mode effects. If a structure is designed to account for these effects, it may be uneconomical, but if it is not designed to account for them, it may be unsafe. The purpose of this thesis is to develop recommendations for the design of controlled rocking steel frames, particularly with regard to higher mode effects. A theoretical framework for understanding higher mode effects is developed, and large-scale shake table testing is used to study the behaviour of a controlled rocking steel frame. Two mechanisms are proposed to mitigate the increase in structural forces due to higher mode effects, and these mechanisms are validated by shake table testing. Numerical modelling of controlled rocking steel frames is shown to become more reliable when higher mode mitigation mechanisms are used to limit the seismic response. In the final chapters, the thesis proposes and validates a new methodology for the limit states design of controlled rocking steel frames.
707

Hydrological and erosion responses to man-made and natural disturbances : insights from forested catchments in South-central Chile

Mohr, Christian Heinrich January 2013 (has links)
Logging and large earthquakes are disturbances that may significantly affect hydrological and erosional processes and process rates, although in decisively different ways. Despite numerous studies that have documented the impacts of both deforestation and earthquakes on water and sediment fluxes, a number of details regarding the timing and type of de- and reforestation; seismic impacts on subsurface water fluxes; or the overall geomorphic work involved have remained unresolved. The main objective of this thesis is to address these shortcomings and to better understand and compare the hydrological and erosional process responses to such natural and man-made disturbances. To this end, south-central Chile provides an excellent natural laboratory owing to its high seismicity and the ongoing conversion of land into highly productive plantation forests. In this dissertation I combine paired catchment experiments, data analysis techniques, and physics-based modelling to investigate: 1) the effect of plantation forests on water resources, 2) the source and sink behavior of timber harvest areas in terms of overland flow generation and sediment fluxes, 3) geomorphic work and its efficiency as a function of seasonal logging, 4) possible hydrologic responses of the saturated zone to the 2010 Maule earthquake and 5) responses of the vadose zone to this earthquake. Re 1) In order to quantify the hydrologic impact of plantation forests, it is fundamental to first establish their water balances. I show that tree species is not significant in this regard, i.e. Pinus radiata and Eucalyptus globulus do not trigger any decisive different hydrologic response. Instead, water consumption is more sensitive to soil-water supply for the local hydro-climatic conditions. Re 2) Contradictory opinions exist about whether timber harvest areas (THA) generate or capture overland flow and sediment. Although THAs contribute significantly to hydrology and sediment transport because of their spatial extent, little is known about the hydrological and erosional processes occurring on them. I show that THAs may act as both sources and sinks for overland flow, which in turn intensifies surface erosion. Above a rainfall intensity of ~20 mm/h, which corresponds to <10% of all rainfall, THAs may generate runoff whereas below that threshold they remain sinks. The overall contribution of Hortonian runoff is thus secondary considering the local rainfall regime. The bulk of both runoff and sediment is generated by Dunne, saturation excess, overland flow. I also show that logging may increase infiltrability on THAs which may cause an initial decrease in streamflow followed by an increase after the groundwater storage has been refilled. Re 3) I present changes in frequency-magnitude distributions following seasonal logging by applying Quantile Regression Forests at hitherto unprecedented detail. It is clearly the season that controls the hydro-geomorphic work efficiency of clear cutting. Logging, particularly dry seasonal logging, caused a shift of work efficiency towards less flashy and mere but more frequent moderate rainfall-runoff events. The sediment transport is dominated by Dunne overland flow which is consistent with physics-based modelling using WASA-SED. Re 4) It is well accepted that earthquakes may affect hydrological processes in the saturated zone. Assuming such flow conditions, consolidation of saturated saprolitic material is one possible response. Consolidation raises the hydraulic gradients which may explain the observed increase in discharge following earthquakes. By doing so, squeezed water saturates the soil which in turn increases the water accessible for plant transpiration. Post-seismic enhanced transpiration is reflected in the intensification of diurnal cycling. Re 5) Assuming unsaturated conditions, I present the first evidence that the vadose zone may also respond to seismic waves by releasing pore water which in turn feeds groundwater reservoirs. By doing so, water tables along the valley bottoms are elevated thus providing additional water resources to the riparian vegetation. By inverse modelling, the transient increase in transpiration is found to be 30-60%. Based on the data available, both hypotheses, are not testable. Finally, when comparing the hydrological and erosional effects of the Maule earthquake with the impact of planting exotic plantation forests, the overall observed earthquake effects are comparably small, and limited to short time scales. / Landmanagement und tektonische Prozesse haben einen erheblichen Einfluss auf das Abflussverhalten und den Wasser-, sowie den Sedimenthaushalt von Gebirgsregionen. Sowohl forstwirtschaftliche Bewirtschaftung, als auch starke Erdbeben sind Impulse, die hydrologische und Erosionsprozesse, sowie deren Prozessraten beeinflussen. Obwohl zahlreiche Arbeiten bereits den Einfluss von forstlicher Bewirtschaftung (Abholzungen, Aufforstungen) als auch von Erdbeben auf Wasser und Sedimentflüsse dokumentiert haben, bleiben wichtige Fragen offen. Wie entscheidend ist der Zeitpunkts der Abholzung und des nachfolgenden Wiederaufforstens? Wie wirken seismische Störungen auf unterirdische Wasserflüsse? Wie ändert sich die geomorphologische Arbeit nach Kahlschlägen? Zur Erforschung dieser Fragen bietet sich das südliche Zentralchile aufgrund seiner hohen lokalen seismischen Aktivität und der kontinuierlichen Umwidmung von Flächen in hochproduktive Plantagenwälder hervorragend an. Letztere verursachen sich häufig verändernde Umweltbedingungen durch kurze forstwirtschaftliche Rotationszyklen. Diese Dissertation betrachtet Einzugsgebiete mit vergleichbarer naturräumlicher Ausstattung. Dabei werden experimentelle Datenerhebung, ein Monitoring-Programm und Datenanalysetechniken mit prozessbasierter Modellierung kombiniert. Ziel der vorliegenden Arbeit ist: 1) die Untersuchung des Einflusses von Plantagenwäldern auf den lokalen Wasserhaushalt. Hier zeigt sich, dass die Baumart (Pinus radiata vs. Eucalyptus globulus) keinen entscheidenden Einfluss auf die lokale Wasserbilanz hat. Vielmehr ist der Bodenwasserspeicher unter dem gegebenen lokalen Hydroklima der entscheidende Faktor für den Wasserverbrauch. 2) die Untersuchung des Verhaltens von Kahlschlagflächen im Hinblick auf Quellen oder Senkenwirkung für Oberflächenabfluss und Sedimenttransport. Hier zeigt sich, dass diese Flächen sowohl als Quelle als auch als Senke für Oberflächenabfluss und Sedimenttransport wirken können – abhängig von der Regenintensität. Übersteigt diese ~20 mm/h, was <10 % der lokalen Niederschlagsereignisse entspricht, generieren Kahlschlagflächen Horton-Oberflächenabfluss (Infiltrationsüberschuss) und Sedimenttransport. Unterhalb dieses Schwellenwerts wirken sie als Senke. In Anbetracht der lokalen Niederschlagintensitäten ist der Gesamtbeitrag des Horton-Oberflächenabflusses daher sekundär. Der Großteil des Abflusses entsteht durch Dunne-Oberflächenabfluss (Sättigungsüberschuss). Zudem zeigt die vorliegende Arbeit, dass Abholzen die Infiltrabilität erhöhen kann. Dies führte dazu, dass zunächst der Gebietsabfluss abfällt bevor er erst nach Auffüllen des Grundwasserspeichers signifikant ansteigt. 3) Die Untersuchung des Einflusses von Kahlschlägen auf die hydro-geomorphologische Arbeit und ihre Effizienz. Durch das Anwenden von Quantile Regression Forests (QRF) wird auf kurzer Prozessskala gezeigt, dass Abholzung zu unterschiedlicher Jahreszeit zu signifikanten Veränderungen im Sedimenttransport führt. Vor allem Kahlschläge die während der Trockenzeit durchgeführt werden, verursachten einen Bedeutungsverlust von seltenen, stärkeren Abflussereignissen zu Gunsten der häufigeren, jedoch weniger starken Ereignissen. Hierbei dominierte der Dunne-Oberflächenabfluss. Dies stimmt mit den Ergebnissen eines prozessbasierten hydrologischen Modells (WASA-SED) überein. Es ist somit eindeutig die Jahreszeit, die die Leistung der hydro-geomorphologischer Arbeit nach Kahlschlägen prägte. 4) die Untersuchung von Grundwasserreaktionen auf das M8.8 Maule Erdbeben. Unter Grundwasserbedingungen kann der gesättigte Saprolith mit Verdichtung auf die Erdbebenerschütterungen reagieren. Dieser Prozess erhöht den hydraulischen Gradienten, der eine plausible Erklärung für den beobachteten Anstieg am Gebietsausfluss nach dem Erdbeben liefert. Die Verdichtung mobilisiert Grundwasser, das zudem von der ungesättigten Bodenmatrix aufgenommen werden kann. Hierdurch erhöht sich das Wasservolumen im Wurzelraum und begünstigt die Pflanzaktivität. Eine solche Aktivitätserhöhung spiegelt sich in verstärkten Tagesgängen wider. 5) die Untersuchung von hydrologischen Reaktionen auf das Erdbeben in der ungesättigten Zone. Hier zeigt sich, dass auch Bodenwasser aus der ungesättigten Bodenzone durch Erdbebenerschütterungen freigesetzt werden kann und den darunter liegenden Grundwasserspeicher zufließt. Hierdurch steigt der Grundwasserspiegel in den Talböden und erhöht dort die Pflanzenwasserverfügbarkeit. Durch inverse Modellierung wurde ein erdbebenbedingter Anstieg der Pflanzenaktivität von 30-60% quantifiziert. Beide Hypothesen sind jedoch auf Basis der verfügbaren Daten nicht eindeutig verifizierbar. Vergleicht man den Effekt des Erdbebens auf den Wasserhaushalt mit dem Effekt der exotischen Plantagenwälder zeigt sich, dass die Gesamtwirkung des Erdbebens auf den Wasserhaushalt vergleichsweise klein war und sich zudem auf kurze Zeiträume beschränkte.
708

Seismic Shift

Vice President Research, Office of the 12 1900 (has links)
Saving lives, securing critical infrastructure and avoiding business interruptions during earthquakes: Terje Haukaas looks to shift the future towards performance-based engineering.
709

Community vulnerability and capacity in post-disaster recovery: the cases of Mano and Mikura neighbourhoods in the wake of the 1995 Kobe earthquake

Yasui, Etsuko 05 1900 (has links)
This is a study of how two small neighbourhoods, Mano and Mikura, recovered from the 1995 Kobe (Japan) earthquake, with a particular focus on the relationship between community vulnerability and capacity. Few studies have examined these interactions, even though vulnerability reduction is recognized to be a vital component of community recovery. Drawing from literature on disaster recovery, community development, vulnerability analysis, community capacity building and the Kobe earthquake, a community vulnerability and capacity model is elaborated from Blaikie et al.’s Pressure and Release Model (1994) to analyze the interactions. The Mano and Mikura cases are analyzed by applying this model and relating outcomes to the community’s improved safety and quality of community lives. Based on the experience of Mano, appropriate long-term community development practices as well as community capacity building efforts in the past can contribute to the reduction of overall community vulnerability in the post-disaster period, while it is recovering. On the other hand, the Mikura case suggests that even though the community experiences high physical and social vulnerability in the pre-disaster period, if the community is able to foster certain conditions, including active CBOs, adequate availability and accessibility to resources, and a collaborative working relationship with governments, the community can make progress on recovery. Although both Mano and Mikura communities achieved vulnerability reduction as well as capacity building, the long-term sustainability of the two communities remains uncertain, as issues and challenges, such as residual and newly emerging physical vulnerability, negative or slow population growth and aging, remained to create vulnerability to future disasters. The case studies reveal the interactions of community vulnerability and capacity to be highly complex and contingent on many contextual considerations.
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Design of Controlled Rocking Steel Frames to Limit Higher Mode Effects

Andree Wiebe, Lydell Deighton 14 January 2014 (has links)
Because conventional seismic force resisting systems rely on yielding of key structural members to limit seismic forces, structural damage is expected after a design-level earthquake. Repairing this damage can be very expensive, if it is possible at all. Researchers have been developing a new family of self-centring systems that avoid structural damage. One such system is a controlled rocking steel frame, which is the subject of this thesis. In a controlled rocking steel frame, the columns of a frame are permitted to uplift from the foundation, and the response is controlled by using a combination of post-tensioning and energy dissipation. Although previous studies have confirmed the viability of this system, they have also shown that rocking does not fully limit the peak seismic forces because of higher mode effects. If a structure is designed to account for these effects, it may be uneconomical, but if it is not designed to account for them, it may be unsafe. The purpose of this thesis is to develop recommendations for the design of controlled rocking steel frames, particularly with regard to higher mode effects. A theoretical framework for understanding higher mode effects is developed, and large-scale shake table testing is used to study the behaviour of a controlled rocking steel frame. Two mechanisms are proposed to mitigate the increase in structural forces due to higher mode effects, and these mechanisms are validated by shake table testing. Numerical modelling of controlled rocking steel frames is shown to become more reliable when higher mode mitigation mechanisms are used to limit the seismic response. In the final chapters, the thesis proposes and validates a new methodology for the limit states design of controlled rocking steel frames.

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