This paper presents the experimental results obtained with the non-contact three-dimensional deformation measuring system–ARAMIS and finite element analysis performed using ANSYS of three slabs made ...of high-performance concrete (HPC) and hybrid (steel/ST and polypropylene/PP) fibre reinforced high-performance concrete (FRHPC). The research was performed on reinforced concrete (RC) slabs with a web mesh of ϕ8 mm bars. All the slabs had an identical amount of steel bars and differed by the fibre volume content. The main objective of the research was to determine the impact of adding polypropylene and steel fibres on the carrying capacity and ductility of HPC slabs. Analysis of the results was conducted based on load–deflection curves, crack distribution, vertical displacements and strains. The research findings indicate that fibres may improve peak strength. The presence of PP and ST hybrid fibres in HPC restricted the propagation of cracks. The energy absorption capacity as well as the ductility index of HPC can be raised by adding hybrid fibres. A comparison of the experimental test results with the nonlinear finite element analysis is made. The numerical results concurred well with the experimental data. The research results indicate that non-contact measurement of deformation is an effective tool for monitoring crushing in FRHPC slabs.
Geospatial deformations are very important in some countries and may lead to catastrophes. For this purpose we need to find practical accurate ways to provide continuous monitoring and measurement to ...allow protection and secure safety. Some countries are suffering great losses such as Jordan where the major high way that connects the north to the middle of the country is closed most of the winter due to landslides that push the road away. In this work we are employing new Geomatics technique to analyze, monitor and measure the landslides. An application of geodetic monitoring of a major landslide on the highway linked Amman to the north (Jerash, Irbid). For the purpose of monitoring the landslide we designed a geodetic network, which consists of 4 points. Measurements were carried out over the period 2007 to 2012 (before and after rainy season) of 12 points within the network. The obtained results are compared to results published previously using different techniques of measurement over the two years period (2002-2004). In the new methodology, GPS receivers and total stations of high precision were used in addition to an orthophoto of two aerial photographs. The observations adjustment and the deformation analysis were executed using locally developed computer programs. The study enabled us to determine a value of 0.26 m/year as an average displacement of the landslide-prone area for the period of 2007-2012. Doi: 10.12777/ijse.4.2.2013.92-96 How to cite this article: Rawashdeh, S., Ruzouq, R.E., and Qtaishat, K.S.. (2013). The use of geomatic techniques to monitor environmental deformation. International Journal of Science and Engineering, 4(2),92-96. Doi: 10.12777/ijse.4.2.2013.92-96
Ionic polymer metal composites (IPMCs) are emerging materials used to realize motion sensors and actuators. In the former case by bending an IPMC membrane a voltage output is obtained, while in the ...latter case a voltage input is able to cause the membrane to bend.
Although a number of interesting properties have been described for such materials, few results have been obtained regarding their characterization.
In this paper a system devoted to the characterization of IPMCs as motion sensors is presented. The system was built in order to study the IPMC reaction, in a large range of frequencies, to a mechanical bending stimulus, in a cantilever configuration.
An IPMC strip acts as the movable capacitive plate between two fixed plates, inside a differential capacitive measuring system. The motion of the IPMC is transduced into the system output voltage, without any mechanical contact, while ad-hoc electronics detect the IPMC sensing output voltage.
A description of the IPMC characterization system follows a brief introduction to IPMC behaviour as sensors and actuators. Then, steps devoted to evaluation of the relationship between the input displacement forced to the IPMC being tested and the corresponding IPMC voltage output are derived.
Current deformation measurement techniques suffer from limited spatial resolution. In this work, a highly accurate and high-resolution Horn Schunck optical flow method is developed and then applied ...to measuring the static deformation of a birdlike flexible airfoil at a series of angles of attack at Reynolds number 100,000 in a low speed, low noise wind tunnel. To allow relatively large displacements, a nonlinear Horn-Schunck model and a coarse-to-fine warping process are adopted. To preserve optical flow discontinuities, a nonquadratic penalization function, a multi- cue driven bilateral filtering and a principle component analysis of local image patterns are used. First, the accuracy and convergence of this Horn-Schunck technique are verified on a benchmark. Then, the maximum displacement that can be reliably calculated by this technique is studied on synthetic images. Both studies are compared with the performance of a Lucas-Kanade optical flow method. Finally, the Horn-Schunck technique is used to estimate the 3-D deformation of the birdlike airfoil through a stereoscopic camera setup. The results are compared with those computed by Lucas-Kanade optical flow, image correlation and numerical simulation.
An inverse approach for the identification of pressure loading on a structure has been proposed and developed. In this approach, surface measurements of structural response (e.g. strain, displacement ...and velocity field measurements, such as can be measured with 3D digital image correlation) are utilized as input data and are combined with numerical simulations to identify the pressure load on a structure. The inverse approach has been verified by numerical benchmarks involving pressure identification under quasi-static as well as dynamic impulse loading conditions, and also been validated by an experiment involving a quasi-static pressure load. The results indicate that the proposed inverse method can identify not only the magnitude of the quasi-static pressure but also the impulsive pressure loading history. The developed inverse approach offers an opportunity to apply inverse analysis techniques to identify interactive pressure loads (such as those resulting from a blast wave) on structures in explosive events.
Like every civil engineered structure tunnels are subject to an ageing process. The reasons for the degrading of the condition are manifold: not fully completed stress redistribution, deterioration ...in the rock mass quality through long‐term exposure (creeping), weathering or dynamic loads and stresses, to name but a few. All this processes lead to a deformation of the surrounding bedrock and the lining.
For a continuous monitoring of a tunnel condition the measurement of the deformation is necessary. Conventional methods are elaborate and time‐consuming and require almost always a shutdown of the tunnel for traffic. Therefore, an inspection is done selectively with large time gaps. A continuous condition assessment becomes hardly possible. Currently no robust method for permanent monitoring of tunnels exists. With a fibre optic measuring method many of these restrictions can be overcome. In the course of this research project, a novel and innovative measuring methodology has been developed to continuously and extensively measure rock deformations. The measurement results were evaluated performing laboratory tests. Subsequently, they were installed in the course of a field test at the Semmering Base Tunnel. With complementary technologies such as laser scanning, the measurement methodology could be verified for its applicability.
Wie jedes andere Ingenieurbauwerk sind auch Tunnel einem Alterungsprozess unterworfen. Die Gründe für eine Verschlechterung des Zustands können vielfältig sein: Nicht abgeschlossene Spannungsumlagerung, Verschlechterung der Gebirgsqualität durch Langzeitbeanspruchung, Verwitterung oder dynamische Beanspruchung, um nur einige zu nennen. Alle diese Vorgänge führen zu Deformationen von Gebirge bzw. Ausbau, die wiederum Schäden verursachen und die Betriebssicherheit beeinträchtigen können.
Zur kontinuierlichen Überwachung des Zustands von Tunneln ist die Messung dieser Deformation notwendig. Dies ist mit herkömmlichen Mitteln aufwändig und erfordert meist eine Tunnelsperre. Daher wird eine Überprüfung nur punktuell und in großen Zeitabständen vorgenommen, wodurch eine laufende Bewertung des Zustands kaum möglich ist. Eine robuste Methode zur permanenten Überwachung von Tunneln existiert derzeit nicht. Mit faseroptischen Messverfahren sind viele dieser Einschränkungen lösbar. Im Zuge eines Forschungsprojekts wurde eine neuartige und innovative Messmethodik entwickelt, um Gebirgsverformungen kontinuierlich und flächendeckend zu messen. Die Messergebnisse wurden anhand eines Laborversuchs überprüft. In weiterer Folge wurden diese im Zuge eines Feldversuchs am Semmering‐Basistunnel eingebaut. Mit komplementären Technologien wie Laserscanning konnte die Messmethodik auf ihre Anwendbarkeit verifiziert werden.
Autogenous deformation and thermal dilation produce stresses, which may lead to cracking in early age concrete subjected to external restraint. To quantify the two types of “free deformation” by ...measurements is a prerequisite to fundamental understanding, as well as to formulate numerical models for use in stress calculations. However, results reported in the literature reveal large deviations and also inconsistencies between different measuring methods. The present paper discusses free deformation measurements and show that different types of measuring errors are involved, where, for instance, reabsorption of bleed water is an important one, and a standard test procedure should therefore describe how to handle the effect of bleeding. Furthermore, it is possible to obtain fairly good reproducibility within one laboratory using the same test rig, whereas a Round-Robin test program showed that it is far more difficult to produce similar results from different laboratories measuring on the same concrete. The implication is that measuring errors were present. Hence, there is a need for more calibration work and better control of test rig behavior.
The complicated tectonics of the Mediterranean region, dominated by the subduction of the African plate under Eurasia, affects the whole of Greece. A significant extension rate across the Aegean sea ...is estimated from satellite geodetic observations, while intense seismicity is observed in parts of the Hellenic arc, manifested by strong earthquakes (Ms>6) of intermediate depth that take place along it.
In Western Greece, the Ionian Islands are situated in a transitional zone (from the Hellenic subduction to the Adriatic collision), characterised by a high crustal deformation rate as revealed by the high seismicity of this zone, the highest in Greece, and the GPS velocity field estimated for the region. In this part of the Aegean plate, transcurrent fault systems dominate, one of which is the Kephalonia Transform Fault (KTF), located offshore the Kephalonia and Lefkada Islands, with a right-lateral slip of the order of 3cm/year.
In the present work an attempt is made to assess the Coulomb stress change associated with well documented earthquake activity, from 1973 to 2003, in the Ionian Island of Lefkada. The results of this study suggest that the early 1973 event did not influence any subsequent moderate earthquakes in the area. On the other hand, the 1994 earthquake may have triggered the north segment of the 2003 event, while the 2003 earthquake ruptured two segments with the north one initiating rupture on the south segment.
: Computer‐aided, personal computer (PC) based, optoelectronic holography (OEH) was used to obtain preliminary measurements of the sound‐induced displacement of the tympanic membrane (TM) of cadaver ...cats and chinchillas. Real‐time time‐averaged holograms, processed at video rates, were used to characterise the frequency dependence of TM displacements as tone frequency was swept from 400 Hz to 20 kHz. Stroboscopic holography was used at selected frequencies to measure, in full‐field‐of‐view, displacements of the TM surface with nanometer resolution. These measurements enable the determination and the characterisation of inward and outward displacements of the TM. The time‐averaged holographic data suggest standing wave patterns on the cat’s TM surface, which move from simple uni‐modal or bi‐modal patterns at low frequencies, through complicated multimodal patterns above 3 kHz, to highly ordered arrangements of displacement waves with tone frequencies above 15 kHz. The frequency boundaries of the different wave patterns are lower in chinchilla (simple patterns below 600 Hz, ordered patterns above 4 kHz) than cat. The stroboscopic holography measurements indicate wave‐like motion patterns on the TM surface, where the number of wavelengths captured along sections of the TM increased with stimulus frequency with as many as 11 wavelengths visible on the chinchilla TM at 16 kHz. Counts of the visible number of wavelengths on TM sections with different sound stimulus frequency provided estimates of wave velocity along the TM surface that ranged from 5 m s−1 at frequencies below 8 kHz and increased to 25 m s−1 by 20 kHz.
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