The results of man-made systems have moved the pendulum towards a new era of man's dominance over earth's ecological, geological, and geographical balance. The history of the industrial agricultural system in particular has left remnants of control on the American landscape, to the detriment of natural resources and our own symbiosis with the environment. The technology that has allowed the system to flourish now prevents us from its future. Ensuring the sustainability of food security must address the current problems of the system itself. Considering architecture's role as an extension of man's control frames this problem as one that can be alleviated through design, providing solutions for our extreme and fatalistic future. As we move into an age of resource scarcity and pre-apocalyptic advancements in technology, Central Valley, California operates as a landscape affected by this overexploitation of capitalism. Monocultures of almond orchards have led to aquifer depletion, colony collapse disorder, a crop extinction. Anthropocenic Landscapes aims to stave off catastrophe through the co-establishment of resource management, agribusiness, research stations, and agro-tourism through a series of ancillary productive towers in the landscape; a new infrastructure is formed to allow the industrial agricultural complex to sustain itself past the point at which resources become almost non-existent. / 1 / SPK / archives@tulane.edu

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As karst features are buried into the deep subsurface and isolated from the mechanisms that formed them, they turn into paleokarst. Some karst features, such as hypogene and island karst, have a higher probability of being preserved into the deep subsurface, as opposed to epigene karst. As these features transition from modern karst to paleokarst, they are susceptible to collapse. When an individual passage or room collapses, it results in an increase in the void’s areal and volumetric footprint. In addition, individual passages and rooms have the potential to collapse and coalesce into each other, further increasing the cave footprint. The end result is often a large zone of brecciated collapse. While the porosity has decreased, the collapse process integrates the permeability over a much larger area, which is the reason these collapsed paleokarst features form an important class of hydrocarbon reservoirs, paleokarst reservoirs.

The trend of making more profits for the owners, deregulation of the utility market and need for obtaining permission from regulatory agencies have forced electric power utilities to operate their systems close to the security limits of their generation, transmission and distribution systems. The result is that power systems are now exposed to substantial risks of experiencing voltage collapse. This phenomenon is complex and is localized in nature but has widespread adverse consequences. The worst scenario of voltage collapse is partial or total outage of the power system resulting in loss of industrial productivity of the country and major financial loss to the utility. On-line monitoring of voltage stability is, therefore becoming a vital practice that is being increasingly adopted by electric power utilities. The phenomenon of voltage collapse has been studied for quite some time, and techniques for identifying voltage collapse situations have been suggested. Most suggested techniques examine steady-state and dynamic behaviors of the power system in off-line modes. Very few on-line protection and control schemes have been proposed and implemented. In this thesis, a new technique for preventing voltage collapse is presented. The developed technique uses subset of measurements from local bus as well as neighbouring buses and considers not only the present state of the system but also future load and topology changes in the system. The technique improves the robustness of the local-based methods and can be implemented in on-line as well as off-line modes. The technique monitors voltages and currents and calculates from those measurements time to voltage collapse. As the system approaches voltage collapse, control actions are implemented to relieve the system to prevent major disturbances. The developed technique was tested by simulating a variety of operating states and generating voltage collapse situations on the IEEE 30-Bus test system. Some results from the simulation studies are reported in this thesis. The results obtained from the simulations indicates that the proposed technique is able to estimate the time to voltage collapse and can implement control actions as well as alert operators.

The European Commission 6th Framework Project COCOMAT (Improved MATerial Exploitation at Safe Design of COmposite Airframe Structures by Accurate Simulation of COllapse) was a four and a half year project (2004 to mid-2008) aimed at exploiting the large reserve of strength in composite structures through more accurate prediction of collapse. In the experimental work packages, significant statistical variation in buckling behaviour and ultimate loading were encountered. The variations observed in the experimental results were not predicted in the finite element analyses that were done in the early stages of the project. The work undertaken in this thesis to support the COCOMAT project was initiated when it was recognised that there was a gap in knowledge about the effect of initial defects and variations in the input variables of both the experimental and simulated panels. The work involved the development of stochastic algorithms to relate variations in boundary conditions, material properties and geometries to the variation in buckling modes and loads up to first failure. It was proposed in this thesis that any future design had to focus on the dominant parameters affecting the statistical scatter in the results to achieve lower sensitivity to variation. A methodology was developed for designing stiffened composite panels with improved robustness. Several panels tested in the COCOMAT project were redesigned using this approach to demonstrate its applicability. The original contributions from this thesis are therefore the development of a stochastic methodology to identify the impact of variation in input parameters on the response of stiffened composite panels and the development of Robust Indices to support the design of new panels. The stochastic analysis included the generation of metamodels that allow quantification of the impact that the inputs have on the response using two first order variables, Influence and Sensitivity. These variables are then used to derive the Robust Indices. A significant outcome of this thesis was the recognition in the final report for COCOMAT that the development of a validated robust index should be a focus of any future design of postbuckling stiffened panels.

The European Commission 6th Framework Project COCOMAT (Improved MATerial Exploitation at Safe Design of COmposite Airframe Structures by Accurate Simulation of COllapse) was a four and a half year project (2004 to mid-2008) aimed at exploiting the large reserve of strength in composite structures through more accurate prediction of collapse. In the experimental work packages, significant statistical variation in buckling behaviour and ultimate loading were encountered. The variations observed in the experimental results were not predicted in the finite element analyses that were done in the early stages of the project. The work undertaken in this thesis to support the COCOMAT project was initiated when it was recognised that there was a gap in knowledge about the effect of initial defects and variations in the input variables of both the experimental and simulated panels. The work involved the development of stochastic algorithms to relate variations in boundary conditions, material properties and geometries to the variation in buckling modes and loads up to first failure. It was proposed in this thesis that any future design had to focus on the dominant parameters affecting the statistical scatter in the results to achieve lower sensitivity to variation. A methodology was developed for designing stiffened composite panels with improved robustness. Several panels tested in the COCOMAT project were redesigned using this approach to demonstrate its applicability. The original contributions from this thesis are therefore the development of a stochastic methodology to identify the impact of variation in input parameters on the response of stiffened composite panels and the development of Robust Indices to support the design of new panels. The stochastic analysis included the generation of metamodels that allow quantification of the impact that the inputs have on the response using two first order variables, Influence and Sensitivity. These variables are then used to derive the Robust Indices. A significant outcome of this thesis was the recognition in the final report for COCOMAT that the development of a validated robust index should be a focus of any future design of postbuckling stiffened panels.

<p> A research program is presented for assessing the plastic collapse load and incremental collapse load of reinforced concrete frames. This investigation attempts to establish a range of validity of simple plastic theory when applied to the under reinforced concrete frames and to determine the sensitivity of such structures to variable repeated loading. </p> <p> An experimental program was conducted on 4 reinforced concrete frames and two reinforced concrete columns. Deflections and strains of these models of nearly prototype size were measured and compared with predicted values at critical cross-sections. </p> <p> Resulting conclusions and recommendations for further research are made. </p> / Thesis / Master of Engineering (MEngr)

This thesis investigates the WCSPH model by considering fluid entry and exit, and integrates the WCSPH method into a new, novel, particle-based Bluff Morphology Model (BMM). Using the BMM, this thesis investigates the stability, collapse and equilibrium position of soft coastal bluffs (cliffs). Fluid and floating object interaction using a novel adaptation of the WCSPH method is investigated by incorporating a floating object model. In particular, this thesis examines the water impact, hydrodynamic forces, fluid motions, and movement of objects in the conventional case studies of object entry and exit from still water. A two-dimensional wedge drop analysis was examined, and the hydrodynamic forces show acceptable agreement with published experimental and numerical results. Simulations for water entry and exit of a buoyant and neutral density cylinder compares well with the previous experimental, numerical and empirical studies. These results provide a good foundation to evaluate the accuracy and stability of WCSPH for modelling complex flows, and therefore offers a platform for the use of WCSPH in a Bluff Morphology Model. The BMM combines a multiple wedge displacement method with an adapted Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) method. At first the wedge method is applied to compute the stability of the bluff. Once the critical failure mechanism of the bluff slope has been identified, if the Factor of Safety for the mechanism is less than 1, the adapted WCSPH method is used to predict the failure movement and residual shape of the slope. The model is validated against benchmark test cases of bluff stability for purely frictional, purely cohesive, and mixed strength bluff materials including 2D static water tables. The model predictions give a good correlation with the expected values, with medium resolution models producing errors of typically less than 2.0%. In addition, the prediction of lateral movement of a surveyed cliff and the dynamic collapse of a vertical bluff are computed, and compare well with published literature. This model is further extended to then investigate the effect of two dimensional seepage on the stability and collapse of soil slopes and levees. To incorporate the seepage in the model, Darcy’s Law is applied to the interactions among neighbouring soil particles and ghost particles are introduced along the enclosed soil boundary to ensure that no fluid crosses the boundary. The contribution of partially saturated soils and matric suction, as well as the change in hydraulic conductivity due to seepage, are predicted well by this model. The predicted time evolution of slope stability and seepage induced collapse are in reasonable agreement with the experimental results for homogeneous frictional sand and multiple layered cohesive soils. Rapid drawdown over a sand soil is also investigated, and the location and time of the levee collapse occurrence are captured well. A toe erosion model is incorporated within the numerical model, and the location and quantity of erosion caused by lateral seepage is well predicted. The interplay of erosion, seepage and slope instability is examined.

Historical collapse events are testament to the inherent dangers of non-robust structures. Designing robust structures is vital to ensure that localised damage events, such as the failure of a single structural element, do not lead to catastrophic disproportionate collapse. While the advent of robustness research can be dated to the collapse of the Ronan Point building in 1968, the quantification of robustness remains an active and important research field. The importance of developing effective robustness assessment methods is emphasized by a number of factors. One issue is the growing problem of inspecting, maintaining and ensuring the safety of ageing infrastructure. Older structures are more likely to be non-redundant and are more susceptible to structural defects. Another factor is the pursuit of greater efficiency and design optimisation, which has eliminated traditional design conservatism and many undocumented factors of safety. As a result, modern buildings may be more vulnerable to unforeseen conditions during their service life. The objective of quantifying robustness highlights the need for a new system-oriented perspective on structural performance to complement traditional component-based design. There is, as of yet, no single framework that incorporates all the essential aspects in an explicit, transparent and quantitative manner leading to a comprehensive outcome in terms of quantification of the structural robustness. This thesis focuses primarily on the quantification of redundancy and robustness, with the view that the capacity of a structure to withstand a damage event is an inherent property of the structure, which can be considered complementary to other commonly discussed structural properties, such as strength and ductility. Hence, a comprehensive unified framework for redundancy quantification is proposed, which builds upon existing strength-based measures. The role of structural uncertainties in the quantification of robustness is investigated, with a focus on the importance of the sequence of events which precede the collapse of a structure. Directly incorporating structural uncertainties into robustness quantification typically requires computationally expensive methods such as Monte Carlo simulations. Moreover, such collapse analyses are susceptible to numerical instabilities, further complicating the simulation of multiple collapse scenarios. To address these issues, a novel incremental elastic analysis method is proposed in this thesis, which analyses the full load-displacement relationship of a structure and additionally, has an inbuilt capacity to incorporate structural variability and thus output a spectrum of possible response outcomes.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 175-187). Available also in a digital version from Dissertation Abstracts.