The mechanical behaviour of commercially available ALPORAS aluminium foam with two different densities was studied under tension loading. In addition to the common stress–strain measurements, local ...deformation, notch-opening displacement and damage evolution were determined. The deformation characteristics deviated from those observed in aluminium foams under compression. No deformation bands or plastic instabilities could be observed in tension, which are very frequent in compression of metallic foams. Four regimes were evident in the stress–strain curves and deformation maps: the linear elastic regime, the plastic regime with no significant crack initiation and propagation, the regime of formation of a fracture process zone and, finally, the regime of fracture, where a main crack propagates through the specimen and leads to failure. The fracture strain was only a few per cent, with the higher-density foam showing a larger fracture strain, and the plastic Poisson's ratio was about 0.35. The notched specimens showed increasing fracture strengths in terms of the net section stress with increasing notch depth. It is suggested that a change in stress state, caused by a non-vanishing Poisson's ratio, in front of the notch tip creates an increase of the fracture strength similar to the behaviour in ductile bulk metals.
This book provides an update on the state of the art of hydrodynamic aspects of marine propellers and turbines, covering predictions using numerical and experimental methods, where the numerical ...methods comprise both potential flow panel methods, Navier–Stokes solvers and mixed methods. Open and ducted propellers, as well as azimuthing thrusters are represented, as well as operation in steady conditions, waves and off-design conditions.<false,>The book consists of 16 peer-reviewed scientific papers previously published in Journal of Marine Science and Engineering.
The results of deformation measurements are related to direct safety of engineering structures and human life. To avoid a wrong interpretation of displacements, an appropriate deformation monitoring ...network must be established and the data obtained from deformation monitoring network must be carefully evaluated. Deformation measurements and analysis require the use of very accurate surveying equipment and analysis methods. The Global Positioning System (GPS) meets the requirements stated above and therefore GPS receivers were used for this research. The purpose of this work was to monitor and analyze the deformation at the crest of the Altýnkaya dam caused by the water load at different water levels combined with the dam's weight. The secondary goal was to determine whether GPS measurements could meet the accuracy requirements for dam deformation measurements. As working area the Altýnkaya dam is selected it is rockfill. In order to monitor and examine the deformation, a monitoring network consisting of 6 reference points and 11 object points was established. Measurements were made 4 times over 2 years using dual frequency GPS receivers with static methods. The measurements were performed and point coordinates have been determined. Then differences were calculated between periods and analyzed by iterative weighted transformation and Least Absolute Sum methods to determine the points stability.
Indian Strategic Petroleum Reserves Limited has awarded the packages of constructing underground unlined rock caverns for storage of 1.33 and 1.25 MMT of high sulphur crude oil at Visakhapatnam ...(Andhra Pradesh) and Padur (Karnataka) respectively to Hindustan Construction Company Limited, where‐in Geoconsult is engaged for detailed design and site services.
The unlined rock caverns for oil and gas storage call for site characterization in terms of geology, hydro‐geology, geochemistry, geomechanics and geotechnics, which in turn facilitates assimilation, assessment and amalgamation of all relevant data to establish an overall geological and/or geotechnical framework for the projects. In general, the construction of an underground unlined rock cavern compriseds five principal activities: (i) geological and/or geotechnical site investigations; (ii) stability assessment; (iii) temporary rock supports design; (iv) excavation and related works; and (v) permanent rock supports re‐design according to the observational approach.
This paper outlines (a) the construction stage geological and/or geotechnical investigations to acquire geological/geotechnical data for rock mass quality appraisal as per Q‐system and permanent rock support recommendations, (b) design criterion to utilize the rock itself as the principal structural material, to create as little disturbance as possible during the construction stage, and to add only the required supports, and (c) geotechnical instrumentation and monitoring to measure displacements at the surface and within the rock mass in order to fine‐tune the excavation methods and rock supports, undertaken during construction stage of the project.
Die Sondergesellschaft Indian Strategic Petroleum Reserves Limited beauftragte Hindustan Construction Company Limited mit dem Bau zweier nicht ausgekleideter Felskavernen zur Lagerung von 1,33 bzw. 1,25 Mill. t sauren Rohöls in Visakhapatnam (Andhra Pradesh) und Padur (Karnataka). Geoconsult ist mit der Ausführungsplanung und baubegleitenden Dienstleistungen betraut.
Für die Herstellung der Kavernen zur Rohöl‐ und Gasspeicherung wurden die geologischen, hydrogeologischen, geochemischen, geomechanischen und geotechnischen Eigenschaften erhoben, was eine Erfassung, Zusammenführung und Verschmelzung aller relevanten Daten für den geotechnischen Rahmenplan ermöglichte. Generell umfasst die Ausführung fünf Hauptaktivitäten: (i) geologische und geotechnische Erkundungen; (ii) Stabilitätsberechnungen; (iii) Planung der temporären Stützmaßnahmen; (iv) Ausbruch und begleitende Arbeiten und (v) laufende Anpassung der permanenten Stützmaßnahmen an die Ergebnisse des geotechnischen Messprogramms.
Dieser Artikel stellt (a) die geologischen Erkundungen während der Bauphase zum Zwecke der Erlangung geologischer und geotechnischer Daten zur Bestimmung der Felsqualität, des Q‐Wertes und der permanenten Stützmaßnahmen, (b) die Planungsparameter für die Verwendung des Fels als primären Baumaterials unter möglichst geringer Auflockerung während des Ausbruchs und Einbau der benötigten Stützmittel, sowie (c) die geotechnische Instrumentierung und Monitoring zur Messung von Verschiebungen an der Oberfläche und im Gebirge zur Feinabstimmung der Ausbruchsmethode und der Stützmaßnahmen in der Bauphase, dar.
Verformungsmessungen an Brückentragwerken können im Rahmen von Monitoringmaßnahmen aufschlussreiche Informationen zum Tragverhalten und zum Bauwerkszustand liefern. Geodätische Messverfahren werden ...für diese Durchbiegungsmessungen bevorzugt eingesetzt. Diese Verfahren ermöglichen reflektorlose und messbasisfreie Verformungsmessungen bei Abtastraten von mehreren hundert Kilohertz. Die eingesetzten Laserscanner sind in der Regel sehr teuer, wodurch diese bei Messperioden von mehreren Wochen oder Jahren und gemäßigten Genauigkeitsanforderungen an Attraktivität verlieren. Demgegenüber wird in diesem Beitrag ein relativ preiswertes Verfahren für Verformungsmessungen an Hohlkastenbrücken vorgestellt. Bei diesem Verfahren wird ein Seil oder Draht durch das Brückenbauwerk gespannt. Dieses fungiert als verformungsneutrale Messbasis (“Base‐Line”) und ermöglicht die Messwertaufnahme bzw. die Verformungsmessung mit optischen Wegaufnehmern. Dieses Messverfahren wird im Zuge von Testmessungen an einer semi‐integralen Spannbeton‐Talbrücke im Zuge der Europastraße E18 in Norwegen eingesetzt. Die Voruntersuchungen zu dem Messverfahren, durchgeführte Probemessungen an einer Hohlkastenbrücke im Stadtgebiet von Hannover und erste Ergebnisse der Testmessungen an der Talbrücke in Norwegen werden im folgenden Beitrag präsentiert.
Base‐line deformation measurements on a semi‐integral box girder bridge
Deformation measurements as part of monitoring activities can provide information about the behavior and structural condition of bridge structures. Geodetic measurement methods are preferred for these deflection measurements. These methods allow reflectorless measurements at sampling rates of several hundred kilohertz. But the used laser scanners are very expensive, by this they are losing attractiveness for measurement periods of several weeks or years and in case of moderate accuracy requirements. In contrast, a relatively inexpensive method to measure the deformations of box girder bridges is presented in this paper. In this method, a cable or wire is clamped through the bridge structure. This acts as measurement base (“base‐line") and allows deformation measurements by optical transducers. This measurement method is currently being tested as part of a monitoring program at a semi‐integral viaduct in Norway. Preliminary studies of the measurement method, conducted measurements on a box girder bridge near of Hanover and first results of test measurements at the Norwegian viaduct are presented.
The present paper is about the estimation of lattice deformation from data collected from manufactures directly on site. The aim here is to give evidence that the concept of the Mean Equivalent ...Lattice (MEL), when applied to “on site X-Ray Diffraction” is the basis for a reliable qualification of the material rheology to external solicitations. Such method allows for the identification of lattice deformations without resorting to the computation of the residual stress with using the elasticity constants (i.e. tensile, shear and rigidity constants E, μ, ν); these elasticity constants descend from the classical theory of solid mechanics, where the continuum mechanics and the material isotropic model are the fundaments. Any MEL deformation is instead related to the variation of the d-spacing among lattice planes which are connected to the anisotropic atomic arrangement. So the macroscopic scale is constituted by a number of MELs and related boundaries. The recent on site X-ray diffraction technology may offer effective and easy solutions, with a significant impact on reliability of results, simplification, economy and time consuming.
Masonry component products are increasingly made industrially with reduced variation in mechanical properties. The joint is the only part of the masonry that is affected by manual action and so the ...load bearing capacity is not only determined by the quality of the bricks and mortar used but moreover by the way the masonry has been built and cured. As a result, it may be expected that the largest material variations are at the brick-mortar interfaces. This has been observed as irregular interface bonding with a bonded central area surrounded by fissures. As a consequence of the final shape of the joint, forces concentrate in the central part of the joint and strain variations occur near fissure tips which result in spalling of bricks in experiments. This paper demonstrates the need for detailed deformational measurements in the brick-mortar interface region. To overcome the limitations with traditional measuring instruments, a refined methodology based on the laser speckle technique is introduced in a companion paper Canadian Journal of Civil Engineering, 34(11), 1467 (2007) by the authors of this paper. PUBLICATION ABSTRACT
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