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Modelling creep of high strength concrete
D. Dias-da-Costa,E.N.B.S. Júlio 사단법인 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.6
Recent developments in concrete mixing made possible the production of concretes with high compressive strength showing, simultaneously, high workability. These concretes also present high strengths at young ages, allowing the application of loads sooner. It is of fundamental importance to verify if creep models developed for current concrete still apply to these new concretes. First, a FEM-based software was adopted to test available creep models, most used for normal strength concrete, considering examples with known analytical results. Several limitations were registered, resulting in an incorrect simulation of threedimensional creep. Afterwards, it was implemented a Kelvin-chain algorithm allowing the use of a chosen number of elements, which adequately simulated the adopted examples. From the comparison between numerical and experimental results, it was concluded that the adopted algorithm can be used to model creep of high strength concrete, if the material properties are previously experimentally assessed.
Numerical modelling of a pile-supported embankment using variable inertia piles
Daniel Dias,Jérôme Grippon 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.2
The increasing lack of good quality soils allowing the development of roadway, motorway, or railway networks, as well as large scale industrial facilities, necessitates the use of reinforcement techniques. Their aim is the improvement of the global performance of compressible soils, both in terms of settlement reduction and increase of the load bearing capacity. Among the various available techniques, the improvement of soils by incorporating vertical stiff piles appears to be a particularly appropriate solution, since it is easy to implement and does not require any substitution of significant soft soil volumes. The technique consists in driving a group of regularly spaced piles through a soft soil layer down to an underlying competent substratum. The surface load being thus transferred to this substratum by means of those reinforcing piles, which illustrates the case of a piled embankment. The differential settlements at the base of the embankment between the soft soil and the stiff piles lead to an “arching effect” in the embankment due to shearing mechanisms. This effect, which can be accentuated by the use of large pile caps, allows partial load transfer onto the pile, as well as surface settlement reduction, thus ensuring that the surface structure works properly. A technique for producing rigid piles has been developed to achieve in a single operation a rigid circular pile associated with a cone shaped head reversed on the place of a rigid circular pile. This technique has been used with success in a pile-supported road near Bourgoin-Jallieu (France). In this article, a numerical study based on this real case is proposed to highlight the functioning mode of this new technique in the case of industrial slabs.
MINERAL CHARACTERISTICS OF RAW GOAT MILK FROM THE REGION OF GOIÂNIA, BRAZIL.
Dias, M.J.,Tanezini, C.A.,D'Alessandro, W.T.,de Oliveria, A.B.C.,Rocha, J. de M.,Pontes, I. dos S.,de Carvalho, A.L.,de Sousa, J.T. Asian Australasian Association of Animal Productio 1994 Animal Bioscience Vol.7 No.1
432 samples of raw goat milk were analyzed for sodium, calcium, potassium, chloride, and ashes content. The samples came from 16 pure breed goats, 2 to 4 years of age kept in semi-feedlots. They were basically fed soy bran, cotton bran, triturated Guandu hay and disintegrated corn with its straw and corncob (according to requirements for due preservation and production). The mean values found were: sodium, $45{\pm}10.2mg%$ (24.5-65.6 mg%); potassium, $206{\pm}44.7mg%$ (116.6-295 mg%); calcium, $111{\pm}22mg%$ (66.5-155.4 mg %); ashes, $0.82{\pm}0.06mg%$ (0.68-0.95%); chloride, $235{\pm}39mg%$ (157-313 mg%). Results were related to: a) breed, the Brown and the Saanen revealed superior values for calcium and ashes, b) climate, which in the rain season led to higher contents of sodium, potassium, and calcium when compared to the local dry season, c) time of lactation which increasingly affected the contents of calcium, sodium and ashes, and d) the time between milking, when higher concentration of chloride and ashes were mostly concentrated in the evening and calcium in the morning. These results have important implications in the handling and management of the goat herd.
Magnetic field dependent behavior of the CDW ground state in Per2M(mnt)2 (M = Au, Pt)
J.S. Brooks,D. Graf,E.S. Choi,M. Almeida,J.C. Dias,R.T. Henriques,M. Matos 한국물리학회 2006 Current Applied Physics Vol.6 No.5
The Per2M(mnt)2 class of organic conductors exhibit a charge density wave (CDW) ground state below about 12 K, which maybe suppressed in magnetic elds of order 2030 T. However, for both cases of counter ion M(mnt)2 species studied (M = Au (zerospin) and M = Pt (spin 1/2)), new high eld ground states evolve for further increases in magnetic eld. We report recent investi-gations where thermopower, Hall eect, high pressure and additional transport measurements have been carried out to explore thesenew high eld phases.
Geochemistry of mudrock units from the Meso-Cenozoic Algarve Basin, Portugal
Maria J. Trindade,Maria I. Dias,Fernando Rocha,Maria I. Prudêncio,Rosa Marques 한국지질과학협의회 2018 Geosciences Journal Vol.22 No.5
Geochemistry of mudrock units deposited in the sedimentary basin of Algarve (South Portugal) during Mesozoic and Cenozoic depositional cycles were studied, aiming a better knowledge of the evolution of the Basin. Two types of mudrock units were found: (i) silicic and Ca-poor (Cretaceous and Cenozoic), and (ii) calcareous (Middle–Upper Jurassic Ca-rich mudrock units and Upper Triassic to Lower Jurassic Mg-rich redbeds). LILE appear to be controlled by a K-bearing phyllosilicate, which is consistent with the abundant illite in the redbeds. Positive trends of: (i) Sc, Cr, Th, LREE with Al2O3 suggests their incorporation in clay minerals, and (ii) HREE with TiO2, Zr and Hf point to their presence in heavy minerals. The source area of the Algarve mudrock units was dominated by felsic rocks; features typical of a mafic source occur in some Upper Triassic to Lower Jurassic samples. Carboniferous metasediments of the basement were probably the first order source for the Algarve sedimentary basin. A more severe weathering in the Cenozoic and Cretaceous mudrock units occurred, whereas diagenetic enrichment in potassium is observed in the Upper Triassic to Lower Jurassic continental redbeds.
Ricardo J.T. Costa,Fernando C.T. Gomes,Paulo M.M.P. Providência,Alfredo M.P.G. Dias 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.4
In the analysis and design of reinforced concrete frames beam-column joints are sometimes assumed as rigid. This simplifying assumption can be unsafe because it is likely to affect the distributions of internal forces and moments, reduce drift and increase the overall load-carrying capacity of the frame. This study is concerned with the relevance of shear deformation of beam-column joints, in particular of exterior ones, on the quasi-static behavior of regular reinforced concrete sway frames. The included parametric studies of a simple sub-frame model reveal that the quasi-static monotonic behavior of unbraced regular reinforced concrete frames is prone to be significantly affected by the deformation of beam-column joints.
FREEZING POINT DEPRESSION OF RAW GOAT'S MILK FROM THE REGION OF GOIÂNIA, BRAZIL
de Sousa, J.T.,Dias, M.J.,Tanezini, C.A.,D'Alessandro, W.T.,de Olineira, B.C.,de Melo Rocha, J.,dos Santos Pontes, I. Asian Australasian Association of Animal Productio 1993 Animal Bioscience Vol.6 No.4
Studies at freezing point depression (FPD) for goat milk are described in this paper. The 432 samples of raw goat milk collected in a period of two years and analysed by the use of an electronic cryoscope gave a mean value of FPD: $-0.565{\pm}0.01^{\circ}C$. Statistical significant differences were found between the morning and evening milk. The evening milk showed better quality considering the lactose and others dissolved solutes. Among the Brown, Saanen and Anglo-nubian goats, the greatest increase in FPD, occurred in the Anglo-nubian breed. The statistical analysis revealed a significant breed difference (p<0.05), when climate variation was observed. The superior and inferior values found to the FPD of the caprine milk (-0.545 to $-0.585^{\circ}C$), is important in establishing regional rules, to improve the quality control criteria and legal interpretation of standards found in the pertinent legislation. The results are also important to improve herd management so that one can increase the animal production which will affect the technological composition, and the nutritional characteristics of the resultant products.
Karla P. Monroy,Jordi Delgado,Lídia Sereno,Joaquim Ciurana,Nicolas J. Hendrichs 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.5
Selective Laser Melting (SLM) is an additive technology that produces solid parts by selectively meltingthin layers of metallic powder. SLM can produce significant differences in the final properties due to themelting-consolidation phenomena of the process, which can be controlled by the appropriate parameters. Therefore, the objective of this study was to create a link between the process conditions and the resultingproperties by experimenting in an own-developed SLM machine using CoCrMo powder as material. The fabricated samples were characterized by density, hardness and microstructural properties. The experimentalresults proved the capability of the SLM technique to build high dense samples. The hardnessresults gave evidence of a superior outcome compared to conventional processes. Finally, it was found thatgrain size was defined by scanning speed. Based on the results, a better understanding of the processingprinciples given by the parameters was achieved and improved fabrication quality was promoted.