Behaviour of FRP Confined Concrete Cylinders: Experimental Investigation and Strength Model

The present paper is devoted to investigate the behaviour of FRP confined concrete cylinders subjected under axial compressive loading. A total of 54 FRP confined concrete cylinders with 2 types of FRP composite wrap, Carbone fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP), were tested under monotonic axial compression. The effects of several parameters such as unconfined concrete strength, type of FRP composite and number of FRP layers are investigated. Three different concrete mixes were examined, with a compressive strengths average of 26, 40 and 60MPa. The effective circumferential FRP failure strain and the effect of the effective lateral confining pressure were investigated. Peak axial compressive strength and corresponding strain of unconfined and FRP confined concrete cylinders were compared. The obtained results show that the CFRP reinforced cylinders provide a significant increase in ultimate compression stress compared to the GFRP reinforced ones. A new model is presented to predict the compressive axial strength and corresponding strain of FRP confined columns

Experimental study on compressive behavior and failure analysis of composite concrete confined by glass/epoxy ±55° filament wound pipes

YesThis paper investigates the strength and ductility of concrete confined by Glass/Epoxy ±55° Filament Wound Pipes (GFRP) under axial compression. A total of 24 cylinderical specimens were prepared with expansive and Portland cements, properly compacted and un-compacted for different composite fresh concrete matrix. Test results showed that compressive strength and axial deformation at failure of concrete confined with GFRP tubes increased by an average of 2.85 and 5.57 times these of unconfined concrete, respectively. Macro and micro analyses of GFRP pipes after failure were also investigated. Debonding, whitening, matrix/transfer cracking, delamination and splitting mechanisms were detected at failure, respectively. The experimental results were also employed to assess the reliability of design models available in the literature for confined concrete compressive strength

Harangue de chef avant la bataille: comparaison entre Tite-Live (Histoire Romaine, livre XXVII) et Silius Italicus (Punica, XV, 320-823)

Touhari Ouardia. Harangue de chef avant la bataille: comparaison entre Tite-Live (Histoire Romaine, livre XXVII) et Silius Italicus (Punica, XV, 320-823). In: Vita Latina, N°171, 2004. pp. 121-129

Harangue de chef avant la bataille: comparaison entre Tite-Live (Histoire Romaine, livre XXVII) et Silius Italicus (Punica, XV, 320-823)

Touhari Ouardia. Harangue de chef avant la bataille: comparaison entre Tite-Live (Histoire Romaine, livre XXVII) et Silius Italicus (Punica, XV, 320-823). In: Vita Latina, N°171, 2004. pp. 121-129

Hydrologic Balance and Surface Water Resources of the Cheliff-Zahrez Basin

The Cheliff basin offers a good hydrological example for the possibility of studying the problem which elucidated in the future, because of the unclearity in several aspects and hydraulic installation. Thus, our study of the Cheliff basin is divided into two principal parts: The spatial evaluation of the precipitation: also, the understanding of the modes of the reconstitution of the resource in water supposes a good knowledge of the structuring of the precipitation fields in the studied space. In the goal of a good knowledge of revitalizes them in water and their management integrated one judged necessary to establish a precipitation card of the Cheliff basin for a good understanding of the evolution of the resource in water in the basin and that goes will serve as basis for all study of hydraulic planning in the Cheliff basin. Then, the establishment of the precipitation card of the Cheliff basin answered a direct need of setting to the disposition of the researchers for the region and a document of reference that will be completed therefore and actualized. The hydrological study, based on the statistical hydrometric data processing will lead us to specify the hydrological terms of the assessment hydrological and to clarify the fundamental aspects of the annual flow, seasonal, extreme and thus of their variability and resources surface water

Hydrogeochemical assessment of the Upper Cheliff groundwater (North West Algeria)

International audienceThe quality of the Upper Cheliff groundwater, located in North West Algeria, has in recent years undergone serious deterioration due to uncontrolled discharge of urban wastewaters, intensive use of chemical fertilizers in agriculture as well as to overexploitation. This study aims at analyzing the flow pattern of the Upper Cheliff groundwater, determining its current hydrochemical status and understanding the mineralization processes involved in its chemical quality. Two piezometric and sampling campaigns were carried out in 2008 in high water (April) and low water (October) periods. The major chemical ions (Ca2+, Mg2+, Na+, K+, Cl-, HCO3 (-), NO3 (-), SO4 (2-)) were analyzed in all samples. The piezometric data were mapped and allowed to analyze the groundwater flow conditions, in particular at the boundaries of the aquifer. The interpretation of hydrochemical data was made using various methods (Piper diagram, Stabler classification, base exchanges index, bi-elements scatter diagrams, saturation indices, mapping and multivariate principal component analysis). The results provide a better understanding of this aquifer hydrogeology and hydrochemistry. Several hydrochemical types (chloride-calcium, chloride-sodium and bicarbonate-calcium) characterize the groundwater. Mineralization processes and the origin of salinity are determined by the lithology of the aquifer (dissolution, base exchanges), and by climatic (evaporation) and anthropogenic factors (agricultural and urban wastes). The groundwater in the Upper Cheliff is currently of poor quality. This status is worrying, as this groundwater is an important natural resource for the socio-economic development of this region. Urgent measures must be taken to preserve this resource

Structure, surface composition, and electronic properties of CuInS2 and CuIn(1-x)AlxS2

International audienceCuInS2 and CuIn(1-x)AlxS2 thin films have been deposited on different substrates using the spray pyrolysis technique at 320 degreesC. X-ray diffraction, atomic force microscopy, and scanning electron microscopy were used to characterize the structure of the films; the surface compositions of the films were studied by Auger electrons spectroscopy and energy dispersive spectrometry (EDS), the work function and the photovoltage by the Kelvin method. Using these techniques, we have specified the effect of the nature of the substrate, its surface morphology, and the introduction of small amounts of Al in the layer on the properties of the films. The best crystallized composition of CuInS2 was obtained for deposits on pyrex. This was improved by the introduction of Al atoms. The work function differences (phi(material)-phi(probe)) for CuInS2 and CuIn(1-x)AlxS2 deposited on pyrex were equal to -350 meV and to -400 meV, respectively. Putting Al atoms in the film increases phi(m) (by about 50 meV) and induces the formation of a negative surface barrier. The best composition was obtained for CuInS2 deposited on SnO2 and annealed. Auger studies shows that the concentration of S and C elements increased when the samples were annealed under a vacuum, whereas the concentration of Cu, In, and O decreased. In the case of CuInS2 grown on pyrex, the introduction of Al increases the O, S, and Cl concentrations and reduces Cu and C concentrations. Analysis of the film compositions by EDS gives the following concentrations [Cu]=24.270%, [In]=24.487%, [S]=46.670%, and [Cl]=4.573%. (C) 2002 American Institute of Physics

Structure, surface composition, and electronic properties of beta-In2S3 and beta-In2-xAlxS3

International audiencebeta -In2S3 and beta -In2-xAlxS3 thin films have been deposited on different substrates using the spray pyrolysis technique at 320 degreesC. X-ray diffraction, atomic force microscopy, and scanning electron microscopy were used to characterize the structure of the films; the surface compositions of the films were studied by Auger electrons spectroscopy and energy dispersive spectrometry (EDS), the work function and the photovoltage by the Kelvin method. Using these techniques, we have specified the effect of the nature of the substrate, of its surface morphology, of the introduction of small amounts of Al in the layer, on the properties of the films. The best crystallized of beta -In2S3 were obtained for deposits on pyrex. This was improved by the introduction of Al atoms. The work function differences (phi (material)-phi (probe)) for beta -In2S3 and beta -In2-xAlxS3 deposited on steel were equal to -150 meV and to -180 meV, respectively. Putting Al atoms in the film increases phi (m) (by about 30 meV) and induces the formation of a negative surface barrier. The concentration of In, S, and O elements increased when the samples were annealed under a vacuum, whereas the concentration of carbon decreased. The best composition was obtained for In2S3 deposited on SnO2 and annealed. The introduction of Al increases O and C concentrations and reduce In, Cl, and S concentrations. Analysis of the film compositions by EDS gives the following concentrations [In]=37%, [S]=52%, and [Cl]=11%. (C) 2001 American Institute of Physics

Magnetic field induced alignment of cyanine dye J-aggregates

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