Analysis of unanchored liquid storage tanks under seismic loads

Because of cost, cylindrical, ground supported liquid storage tanks are often not fixed to their foundation, even in seismic areas. For such an unanchored tank made of steel, the weight of the cylindrical shell is mostly insufficient ' to prevent local uplift due to seismic overturning moments. Although, for properly designed connecting pipes, uplift itself is not a problem, it results in larger vertical compressive stresses in the tank wall at the base, opposite to where the uplift occurs. These compressive stresses have often caused buckling, even in earthquakes which did not cause much damage to other structures. Various investigators have studied the behavior of unanchored tanks experimentally, but, due to the complexity of the problem, so far very little theoretical work has been done. Two methods of analysis for static lateral loads are presented: An approximate one in which the restraining action of the base plate is modeled by nonlinear Winkler springs, and a more comprehensive one in which the two dimensional nonlinear contact problem is solved by the finite difference energy method. The theoretical results are compared with existing experimental results and with the approach from current U.S. design standards. The theoretical peak compressive stresses are in good agreement with the experimental results, but in some cases exceed those calculated by the code method by more than 100%. Finally, a new design concept, by which the tank wall is preuplifted all around its circumference by inserting a ring filler is described. It will be shown theoretically and experimentally that this preuplift method substantially improves the lateral load capacity

Some possibilities in on-line analysis-test procedures for earth structures

A procedure for finite element analysis of earth structures in which the stress-strain relations are obtained experimentally as the test proceeds is explored. This requires on-line interactions between the analysis and test results, with the behavior if the soil influencing loading history on the soil samples in the appropriate way. In general, one soil sample is required for each integration point in the finite element mesh, However the number of soil samples required can be reduced by use of a limited number of Ritz modes to represent the deformations.Important recent advances in pseudodynamic test methodology applied to building structures are adapted for use in this on-line analysis-test method. The need to enforce compatibility as well as equilibrium makes this a non-trivial step. A further extension of the method allows dissipation of pore pressures to be accounted for. This is achieved by including the nonlinear generalization of Biot's equations in the analytical part of the procedure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29199/1/0000253.pd

Worst shapes of imperfections for space trusses with multiple global and local buckling modes

The initial postbuckling behavior and imperfection sensitivity of truss-type structures in which the joints do not transmit moments is determined by means of the Lyapunov-Schmidt-Koiter approach. Such structures possess local buckling modes involving the buckling of individual members, and global modes involving axial deformations of all members but no member buckling. Of particular interest is the case in which through optimization (or otherwise) a number of local and global modes are coincident. The worst shape of imperfection for this case is determined from the bifurcated equilibrium branch on which the load drops most rapidly. It is shown that this critical bifurcated branch initially involves the buckling of one member only. The general theory is illustrated by a number of examples involving two- and three-dimensional lattice columns. The leading order asymptotic results for these examples are compared to exact results obtained by tracking the appropriate equilibrium branch numerically.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31104/1/0000782.pd

On stability and the worst imperfection shape in solids with nearly simultaneous eigenmodes

Of interest here is the influence of imperfections on the stability of elastic systems, discrete or continuous, with nearly simultaneous modes. The majority of such structures show an extreme sensitivity of their first instability load to the shape of these small amplitude but unavoidable imperfections. The determination of the worst such possible shape is thus a very important issue from the design standpoint. Following a general analysis of the stability of arbitrary elastic systems with nearly simultaneous bifurcation eigenmodes in the presence of imperfections, conditions are given for the determination of the worst imperfection shape which minimizes the first local load maximum. For the case of coincident eigenmodes the answer to the worst shape problem is considerably simplified, for it is determined from the equilibrium branch of the perfect structure on which the load drops more rapidly.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30374/1/0000776.pd

Worst shapes of imperfections for space trusses with many simultaneously buckling members

Optimally designed truss type structures whose joints do not transmit moments often have a large number of coincident buckling modes. Each mode corresponds to the buckling of an individual member. Due to the interaction between various simultaneous modes, such trusses can be sensitive to imperfections. This problem is analysed using the Lyapunov-Schmidt-Koiter decomposition and asymptotic expansion technique. The shape of the imperfection that maximizes the load drop is determined from the postbifurcated equilibrium branch of the perfect structure on which the load drops most rapidly. It is shown that this branch is obtained by minimizing a homogeneous quadratic form subject to linear inequality constraints. The general theory is illustrated by several examples involving two- and three-dimensional trusses.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30375/1/0000777.pd

Vertical vibrations of circular flexible foundations on layered media

The paper presents the analysis of vertical oscillations of a flexible circular plate on the surface of an elastic half-space and an elastic layered system by the `ring method'. The matrix of influence coefficients for the layered system is evaluated based on the stiffness matrix approach, and numerical integration is used to perform the inverse Hankel transforms. The plate discretization is achieved by the finite difference energy method. Vertical oscillations have been analyzed to determine the displacement and soil reaction distributions at the soil-plate interface, and the impedance functions. The results indicate that the response of a flexible plate strongly depends on the material and geometrical properties of both a soil system and a plate, and the load distribution on the plate. In most cases the behavior of a flexible plate differs significantly from the behavior of a rigid one.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31060/1/0000737.pd

Postbuckling behavior and imperfection sensitivity of elastic structures by the Lyapunov-Schmidt-Koiter approach

Beginning with the work of Koiter in 1945, valuable insights into the postbuckling behavior of structures have been gained by Lyapunov-Schmidt decomposition of the displacements followed by an asymptotic expansion about the bifurcation point. Here this methodology is generalized to include nonlinear prebuckling behavior, as well as multiple, not necessarily coincident buckling modes. The expansion of the reduced equilibrium equations is performed about a reference point (which need not coincide with any of the bifurcation points), and applies no matter whether the modes are coincident, closely spaced, or well separated. From a variety of possible decompositions of the admissible space of displacements, two are incorporated into a finite element program. Theoretical considerations, and numerical examples in which asymptotic results are compared to `exact' results, indicate that one of the decompositions has some important advantages over the other. Examples include a shallow arch, and a beam on elastic foundation problem exhibiting symmetry-breaking modal interaction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30602/1/0000239.pd

PHANGS-ML: Dissecting Multiphase Gas and Dust in Nearby Galaxies Using Machine Learning

The PHANGS survey uses Atacama Large Millimeter/submillimeter Array, Hubble Space Telescope, Very Large Telescope, and JWST to obtain an unprecedented high-resolution view of nearby galaxies, covering millions of spatially independent regions. The high dimensionality of such a diverse multiwavelength data set makes it challenging to identify new trends, particularly when they connect observables from different wavelengths. Here, we use unsupervised machine-learning algorithms to mine this information-rich data set to identify novel patterns. We focus on three of the PHANGS-JWST galaxies, for which we extract properties pertaining to their stellar populations; warm ionized and cold molecular gas; and polycyclic aromatic hydrocarbons (PAHs), as measured over 150 pc scale regions. We show that we can divide the regions into groups with distinct multiphase gas and PAH properties. In the process, we identify previously unknown galaxy-wide correlations between PAH band and optical line ratios and use our identified groups to interpret them. The correlations we measure can be naturally explained in a scenario where the PAHs and the ionized gas are exposed to different parts of the same radiation field that varies spatially across the galaxies. This scenario has several implications for nearby galaxies: (i) The uniform PAH ionized fraction on 150 pc scales suggests significant self-regulation in the interstellar medium, (ii) the PAH 11.3/7.7 μm band ratio may be used to constrain the shape of the non-ionizing far-ultraviolet to optical part of the radiation field, and (iii) the varying radiation field affects line ratios that are commonly used as PAH size diagnostics. Neglecting this effect leads to incorrect or biased PAH sizes

PHANGS-ML: dissecting multiphase gas and dust in nearby galaxies using machine learning

The PHANGS survey uses ALMA, HST, VLT, and JWST to obtain an unprecedented high-resolution view of nearby galaxies, covering millions of spatially independent regions. The high dimensionality of such a diverse multi-wavelength dataset makes it challenging to identify new trends, particularly when they connect observables from different wavelengths. Here we use unsupervised machine learning algorithms to mine this information-rich dataset to identify novel patterns. We focus on three of the PHANGS-JWST galaxies, for which we extract properties pertaining to their stellar populations; warm ionized and cold molecular gas; and Polycyclic Aromatic Hydrocarbons (PAHs), as measured over 150 pc-scale regions. We show that we can divide the regions into groups with distinct multiphase gas and PAH properties. In the process, we identify previously-unknown galaxy-wide correlations between PAH band and optical line ratios and use our identified groups to interpret them. The correlations we measure can be naturally explained in a scenario where the PAHs and the ionized gas are exposed to different parts of the same radiation field that varies spatially across the galaxies. This scenario has several implications for nearby galaxies: (i) The uniform PAH ionized fraction on 150 pc scales suggests significant self-regulation in the ISM, (ii) the PAH 11.3/7.7 \mic~ band ratio may be used to constrain the shape of the non-ionizing far-ultraviolet to optical part of the radiation field, and (iii) the varying radiation field affects line ratios that are commonly used as PAH size diagnostics. Neglecting this effect leads to incorrect or biased PAH sizes.Comment: Main results in figures 6 and 12. Submitted to ApJ, and comments are welcome

Crop Updates 2007 - Farming Systems

This session covers forty papers from different authors: 1. Quality Assurance and industry stewardship, David Jeffries, Better Farm IQ Manager, Cooperative Bulk Handling 2. Sothis: Trifolium dasyurum (Eastern Star clover), A. Loi, B.J. Nutt and C.K. Revell, Department of Agriculture and Food 3. Poor performing patches of the paddock – to ameliorate or live with low yield? Yvette Oliver1, Michael Robertson1, Bill Bowden2, Kit Leake3and Ashley Bonser3, CSIRO Sustainable Ecosystems1, Department of Food and Agriculture2, Kellerberrin Farmer3 4. What evidence is there that PA can pay? Michael Robertson, CSIRO Floreat, Ian Maling, SilverFox Solutions and Bindi Isbister, Department of Agriculture and Food 5.The journey is great, but does PA pay? Garren Knell, ConsultAg; Alison Slade, Department of Agriculture and Food, CFIG 6. 2007 Seasonal outlook, David Stephens and Michael Meuleners, Department of Agriculture and Food 7. Towards building farmer capacity to better manage climate risk, David Beard and Nicolyn Short, Department of Agriculture and Food 8. A NAR farmers view of his farming system in 2015, Rob Grima, Department of Agriculture and Food 9. Biofuels opportunities in Australia, Ingrid Richardson, Food and Agribusiness Research, Rabobank 10. The groundwater depth on the hydrological benefits of lucerne and the subsequent recharge values, Ruhi Ferdowsian1and Geoff Bee2; 1Department of Agriculture and Food, 2Landholder, Laurinya, Jerramungup 11. Subsoil constraints to crop production in the high rainfall zone of Western Australia, Daniel Evans1, Bob Gilkes1, Senthold Asseng2and Jim Dixon3; 1University of Western Australia, 2CSIRO Plant Industry, 3Department of Agriculture and Food 12. Prospects for lucerne in the WA wheatbelt, Michael Robertson, CSIRO Floreat, Felicity Byrne and Mike Ewing, CRC for Plant-Based Management of Dryland Salinity, Dennis van Gool, Department of Agriculture and Food 13. Nitrous oxide emissions from a cropped soil in the Western Australian grainbelt, Louise Barton1, Ralf Kiese2, David Gatter3, Klaus Butterbach-Bahl2, Renee Buck1, Christoph Hinz1and Daniel Murphy1,1School of Earth and Geographical Sciences, The University of Western Australia, 2Institute for Meteorology and Climate Research, Atmospheric Environmental Research, Garmisch-Partenkirchen, Germany, 3The Department of Agriculture and Food 14. Managing seasonal risk is an important part of farm management but is highly complex and therefore needs a ‘horses for courses’ approach, Cameron Weeks, Planfarm / Mingenew-Irwin Group, Dr Michael Robertson, Dr Yvette Oliver, CSIRO Sustainable Ecosystems and Dr Meredith Fairbanks, Department of Agriculture and Food 15. Novel use application of clopyralid in lupins, John Peirce, and Brad Rayner Department of Agriculture and Food 16. Long season wheat on the South Coast – Feed and grain in a dry year – a 2006 case study, Sandy White, Department of Agriculture and Food 17. Wheat yield response to potassium and the residual value of PKS fertiliser drilled at different depths, Paul Damon1, Bill Bowden2, Qifu Ma1 and Zed Rengel1; Faculty of Natural and Agricultural Sciences, The University of Western Australia1, Department of Agriculture and Food2 18. Saltbush as a sponge for summer rain, Ed Barrett-Lennard and Meir Altman, Department of Agriculture and Food and CRC for Plant-based Management of Dryland Salinity 19. Building strong working relationships between grower groups and their industry partners, Tracey M. Gianatti, Grower Group Alliance 20. To graze or not to graze – the question of tactical grazing of cereal crops, Lindsay Bell and Michael Robertson, CSIRO Sustainable Ecosystems 21. Can legume pastures and sheep replace lupins? Ben Webb and Caroline Peek, Department of Agriculture and Food 22. EverGraze – livestock and perennial pasture performance during a drought year, Paul Sanford, Department of Agriculture and Food, and CRC for Plant-based Management of Dryland Salinity 23. Crop survival in challenging times, Paul Blackwell1, Glen Riethmuller1, Darshan Sharma1and Mike Collins21Department of Agriculture and Food, 2Okura Plantations, Kirikiri New Zealand 24. Soil health constraints to production potential – a precision guided project, Frank D’Emden, and David Hall, Department of Agriculture and Food 25. A review of pest and disease occurrence in 2006, Mangano, G.P. and Severtson, D.L., Department of Agriculture and Food 26. e-weed – an information resource on seasonal weed management issues, Vanessa Stewart and Julie Roche, Department of Agriculture and Food 27. Review of Pesticide Legislation and Policies in Western Australia, Peter Rutherford, BSc (Agric.), Pesticide Legislation Review, Office of the Chief Medical Adviser, WA Department of Health 28. Future wheat yields in the West Australian wheatbelt, Imma Farré and Ian Foster, Department of Agriculture and Food, Stephen Charles, CSIRO Land and Water 29. Organic matter in WA arable soils: What’s active and what’s not, Frances Hoyle, Department of Agriculture and Food, Australia and Daniel Murphy, UWA 30. Soil quality indicators in Western Australian farming systems, D.V. Murphy1, N. Milton1, M. Osman1, F.C. Hoyle2, L.K Abbott1, W.R. Cookson1and S. Darmawanto1; 1UWA, 2Department of Agriculture and Food 31. Impact of stubble on input efficiencies, Geoff Anderson, formerly employed by Department of Agriculture and Food 32. Mixed farming vs All crop – true profit, not just gross margins, Rob Sands and David McCarthy, FARMANCO Management Consultants, Western Australia 33. Evaluation of Local Farmer Group Network – group leaders’ surveys 2005 and 2006, Paul Carmody, Local Farmer Group Network, Network Coordinator, UWA 34. Seeding rate and nitrogen application and timing effects in wheat, J. Russell, Department of Agriculture and Food, J. Eyres, G. Fosbery and A. Roe, ConsultAg, Northam 35. Foliar fungicide application and disease control in barley, J. Russell, Department of Agriculture and Food, J. Eyres, G. Fosbery and A. Roe, ConsultAg, Northam 36. Brown manuring effects on a following wheat crop in the central wheatbelt, , J. Russell, Department of Agriculture and Food, J. Eyres, G. Fosbery and A. Roe, ConsultAg, Northam 37. Management of annual pastures in mixed farming systems – transition from a dry season, Dr Clinton Revell and Dr Phil Nichols; Department of Agriculture and Food 38. The value of new annual pastures in mixed farm businesses of the wheatbelt, Dr Clinton Revell1, Mr Andrew Bathgate2and Dr Phil Nichols1; 1Department of Agriculture and Food, 2Farming Systems Analysis Service, Albany 39. The influence of winter SOI and Indian Ocean SST on WA winter rainfall, Meredith Fairbanks and Ian Foster, Department of Agriculture and Food 40. Market outlook – Grains, Anne Wilkins, Market Analyst, Grains, Department of Agriculture and Foo