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This thesis addresses the topic of local bond behaviour in RC structures. The mechanism of bond refers to the composite action between deformed steel reinforcing bars and the surrounding concrete. Bond behaviour is an open research topic with a wide scope, particularly because bond it is such a fundamental concept to structural engineers. However, despite many bond-related research findings having wide applications, the primary contribution of this research is an experimental evaluation of the prominent features of local bond behaviour and the associated implications for the seismic performance of RC structures. The findings presented in this thesis attempt to address some structural engineering recommendations made by the Canterbury Earthquakes Royal Commission following the 2010-2011 Canterbury (New Zealand) earthquake sequence. A chapter of this thesis discusses the structural behaviour of flexure-dominated RC wall structures with an insufficient quantity of longitudinal reinforcement, among other in situ conditions, that causes material damage to predominantly occur at a single crack plane. In this particular case, the extent of concrete damage and bond deterioration adjacent to the crack plane will influence the ductility capacity that is effectively provided by the reinforcing steel. As a consequence of these in situ conditions, some lightly reinforced wall buildings in Christchurch lost their structural integrity due to brittle fracture of the longitudinal reinforcement. With these concerning post-earthquake observations in mind, there is the underlying intention that this thesis presents experimental evidence of bond behaviour that allows structural engineers to re-assess their confidence levels for the ability of lightly reinforced concrete structures to achieve the life-safety seismic performance objective the ultimate limit state. Three chapters of this thesis are devoted to the experimental work that was conducted as the main contribution of this research. Critical details of the experimental design, bond testing method and test programme are reported. The bond stress-slip relationship was studied through 75 bond pull-out tests. In order to measure the maximum local bond strength, all bond tests were carried out on deformed reinforcing bars that did not yield as the embedded bond length was relatively short. Bond test results have been presented in two separate chapters in which 48 monotonic bond tests and 27 cyclic bond tests are presented. Permutations of the experiments include the loading rate, cyclic loading history, concrete strength (25 to 70 MPa), concrete age, cover thickness, bar diameter (16 and 20 mm), embedded length, and position of the embedded bond region within the specimen (close or far away to the free surface). The parametric study showed that the concrete strength significantly influences the maximum bond strength and that it is reasonable to normalise the bond stress by the square-root of the concrete compressive strength, √(f'c). The generalised monotonic bond behaviour is described within. An important outcome of the research is that the measured bond strength and stiffness was higher than stated by the bond stress-slip relationship in the fib Model Code 2010. To account for these observed differences, an alternative model is proposed for the local monotonic bond stress-slip relationship. Cyclic bond tests showed a significant proportion of the total bond degradation occurs after the loading cycle in the peak bond strength range, which is when bond slip has exceeded 0.5 mm. Subsequent loading to constant slip values showed a linear relationship between the amount of bond strength degradation and the log of the number of cycles that were applied. To a greater extent, the cyclic bond deterioration depends on the bond slip range, regardless of whether the applied load cycling is half- or fully-reversed. The observed bond deterioration and hysteretic energy dissipated during cyclic loading was found to agree reasonably well between these cyclic tests with different loading protocols. The cyclic bond deterioration was also found to be reasonably consistent exponential damage models found in the literature. This research concluded that the deformed reinforcing bars used in NZ construction, embedded in moderate to high strength concrete, are able to develop high local bond stresses that are mobilised by a small amount of local bond slip. Although the relative rib geometry was not varied within this experimental programme, a general conclusion of this thesis is that deformed bars currently available in NZ have a relative rib bearing area that is comparatively higher than the test bars used in previous international research. From the parametric study it was found that the maximum monotonic bond strength is significant enhanced by dynamic loading rates. Experimental evidence of high bond strength and initial bond stiffness generally suggests that only a small amount of local bond slip that can occur when the deformed test bar was subjected to large tension forces. Minimal bond slip and bond damage limits the effective yielding length that is available for the reinforcing steel to distribute inelastic material strains. Consequently, the potential for brittle fracture of the reinforcement may be a more problematic and widespread issue than is apparent to structural engineers. This research has provided information that improve the reliability of engineering predictions (with respect to ductility capacity) of maximum crack widths and the extent of bond deterioration that might occur in RC structures during seismic actions.

Αποτύπωση των μεγαλύτερων σεισμών του 20ου αιώνα στον Ελληνικό χώρο από τον εθνικό και επαρχιακό Ελληνικό τύπο.Σύγκριση των δημοσιευμάτων σχετικά με τεσσερις μεγάλους σεισμούς των τελευταίων πενήντα χρόνων. / Recording of the larger scale earthquakes of 20th century in Greece from the national and provincial Greek press. Comparison of publications referring to four of the largest scale earthquakes of the last fifty years.

Transient deformation has been observed in a number of different types of tectonic environments. These transient deformation signals are often observed using continuous GPS (CGPS) position time-series observations. Examining transient deformation using CGPS time-series is problematic due to the, often, low signal-to-noise ratios and variability in duration of transient motions observed. A technique to estimate a continuous velocity function from noisy CGPS coordinate time-series of is examined. The resolution of this technique is dependent on the signal-to-noise ratio and the duration or frequency content of the transient signal being modeled. Short period signals require greater signal-to-noise ratios for effective resolution of the actual transient signal. The technique presented here is similar to a low-pass filter but with a number of advantages when working with CGPS data. Data gaps do not adversely impact the technique but limit resolution near the gap epochs, if there is some a priori knowledge of the noise contained within the time-series this information can be included in the model, and model parameter uncertainties provide information on the uncertainty of instantaneous velocity through time. A large transient has been observed in the North-American stable continental interior as a significant increase in the number and moment release of earthquakes through time. This increase in the number of earthquakes has been suggested to be largely related changes in oil and gas production activities within the region as triggered or induced seismicity, primarily from fluid injection. One of the first observed cases of triggered earthquakes from hydraulic fracturing where the earthquakes were large enough to be felt by local residents is documented. The multiple strong temporal and spatial correlations between these earthquakes indicate that hydraulic fracturing in a nearby well likely triggered the earthquake sequence. The largest magnitude earthquake in this sequence was a magnitude 2.9 with 16 earthquakes greater than magnitude 2. The earthquakes in this sequence occurred within 2.5 km of the hydraulic fracturing operation and focal depths are similar to the depths of hydraulic fracturing treatment depths. In addition to the documentation of a transient earthquake signal associated with hydraulic fracturing, the observed focal mechanisms throughout Oklahoma are documented. These focal mechanisms were used to examine the maximum horizontal stress orientations and active fault orientations associated with the increased rates of seismicity observed in the region. Generally, active-fault orientations and the stresses are consistent through broad portions of Oklahoma with one exception, the ongoing Jones earthquake sequence in central Oklahoma that started in 2009. In the Jones earthquake sequence a bi-modal distribution of focal mechanisms are observed. One orientation of active faults observed in the Jones earthquake sequence would not be expected to be active in the observed regional stress field. This unfavorably oriented set of faults appear to be pre-existing structures and activity on these structures may suggest that pore-pressure increases in the sub-surface due to fluid injection in the area make it possible for faults that are not optimally oriented within the regional stress-field to reactivate.

Christo and Jeanne-Claude’s Running Fence, begun 1972 and installed in 1976, and Niki de St. Phalle’s Queen Califia’s Magical Circle, dedicated 2003, in northern and southern California respectively, reexamine the ways landscape art historically shaped ideological constructs, lived experience, and cultural economics. Christo, Jeanne-Claude, and St. Phalle draw on well known representations of the frontier and American West from the nineteenth century including, antebellum landscapes such as Thomas Cole’s The Oxbow, 1836 and Emmanuel Leutze’s Westward the Course of Empire, 1862 as well as Reconstruction Era landscapes including Andrew Russell’s The Golden Spike, 1869 and John Gast’s American Progress, 1872. When Christo, Jeanne-Claude, and St. Phalle’s West Coast art are viewed together, questions about history and tradition, the relationship of economics to cultural production, and aesthetics informed by place and environment, emerge as salient. Through the artists’ interest in time, place, and environment, as well as sustained engagement with community, Running Fence and Queen Califia’s Magical Circle construct representations of the local and interpret the histories and cultures of Sonoma and Marin Counties and Escondido. Running Fence and Queen Califia’s Magical Circle critically engage with artistic convention, state construction, capitalism and cultural production, and the construction of race, gender, and sexuality. As art historian William Truettner explained historical representations of the western frontier as “national pictures,” so too Running Fence and Queen Califia’s Magical Circle reinterpret historical images of the American West through an emphasis on community and place rather than nation-building and nationalism.

This dissertation explores subduction zone-related deformation both on short time scales in the form of subduction zone earthquakes and over larger time and geographical scales in the form of subduction rollback or detachment of the subducting lithosphere. The study presented here is composed of two parts. First, we analyzed the source-rupture processes of the April 1, 2007 Solomon Islands Earthquake (Mw=8.1) using a body-wave inversion technique. Our analysis indicated that the earthquake ruptured approximately 240 km of the southeast Pacific subduction zone in two sub-events.In the second part of this study, we used shear-wave splitting analysis to investigate the effects of the subducting African lithosphere on the upper-mantle flow field beneath the Anatolian Plate in the Eastern Mediterranean region. Our shear-wave splitting results are consistent with relatively uniform southwest-directed flow towards the actively southwestward-retreating Aegean slab. Based on spatial variations in observed delay times we identified varying flow speeds beneath Anatolia and we attribute this variation to the differential retreat rates of the Aegean and the Cyprean trenches.Finally, we used teleseismic P-wave travel-time tomography to image the geometry of the subducting African lithosphere beneath the Anatolia region. Our tomograms show that the subducting African lithosphere is partitioned into at least two segments along the Cyprean and the Aegean trenches. We observed a gap between the two segments through which hot asthenosphere ascends beneath the volcanic fields of western Anatolia. Our results show that the Cyprean slab is steeper than the Aegean slab. We inferred that this steep geometry, in part, controls the flow regime of asthenosphere beneath Anatolia causing variations in flow speeds inferred from shear-wave splitting analysis.

Earthquakes, such as the ones capable of affecting the Lower Mainland of British Columbia, can have a devastating effect on the environment that people live and work in. The purpose of this thesis is to examine methods of dealing with the hazards and problems created by existing, often historically significant, unreinforced buildings in earthquake-prone areas. Gaining an understanding of the complexity of this problem and the issues involved in establishing hazard mitigation policies gives insight into the policy-making process. The research indicates that a number of internal and external factors affect the formulation, adoption, and implementation of hazard mitigation policies. Despite limited awareness of the problem, low political salience of the issue, and limited resources in most communities, there are many steps that can be taken that will reduce the public's exposure to the risks created by unreinforced buildings and strengthen historically significant buildings that hold value, socially, economically, and culturally. Establishing more extensive mitigative measures, such as implementing a seismic retrofit policy, requires a decision-making process that must involve the people who live and work within that community. Each community, through a process of consultation with the stakeholders, needs to decide if it is in their interest to pursue hazard mitigation strategies to reduce the seismic risk. There is a need to integrate hazard mitigation strategies into the daily decision-making process of politicians and planners. The thesis concludes with some points for stakeholders to consider in designing policy to reduce the earthquake hazard that all the communities in the Lower Mainland of British Columbia face.

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Following a disaster, an organisation’s ability to recover is influenced by its internal capacities, but also by the people, organisations, and places to which it is connected. Current approaches to organisational resilience tend to focus predominantly on an organization's internal capacities and do not adequately consider the place-based contexts and networks in which it is embedded. This thesis explores how organisations’ connections may both hinder and enable organisational resilience. Organisations in the Canterbury region of New Zealand experienced significant and repeated disruptions as a result of two major earthquakes and thousands of aftershocks throughout 2010 and 2011. This thesis draws upon 32 case studies of organisations located in three severely damaged town centres in Canterbury to assess the influence that organisations’ place-based connections and relational networks had on their post-earthquake trajectories. The research has four objectives: 1) to examine the ways organisations connected to their local contexts both before and after the earthquakes, 2) to explore the characteristics of the formal and informal networks organisations used to aid their response and recovery, 3) to identify the ways organisations’ connections to their local contexts and support networks influenced their ability to recover following the earthquakes, and finally, 4) to develop approaches to assess resilience that consider these extra-organisational connections. The thesis contests the fiction that organisations recover and adapt independently from their contexts following disasters. Although organisations have a set of internal capacities that enable their post-disaster recovery, they are embedded within external structures that constrain and enable their adaptive options following a disaster. An approach which considers organisations’ contexts and networks as potential sources of organisational resilience has both conceptual and practical value. Refining our understanding of the influence of extra-organisational connections can improve our ability to explain variability in organisational outcomes following disasters and foster new ways to develop and manage organisational resilience.