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Comportamiento sísmico de silos  [cached]
Carvajal D. álvaro
Ingeniería e Investigación , 1999,
Abstract: En las referencias bibliográficas que corrientemente se manejan sobre dise o de silos, no se encuentra información acerca del cálculo de fuerzas sísmicas usando espectros de respuesta, la herramienta más empleada actualmente en la evaluación de tales fuerzas. Para llenar este vacío, por lo menos en mínima parte, y para explorar procedimientos de estudio referentes al tema, se realizó el trabajo del mismo título del presente artículo, que sirvió como requisito de promoción, y cuyas partes esenciales se mencionan aquí. En consecuencia, el objetivo del estudio fue, según lo indicado arriba, establecer una metodología de cálculo sencilla, de las fuerzas cortantes y momentos flectores producidos por las acciones sísmicas sobre los silos verticales, usando espectros de dise o.
Los empujes del material almacenado en silos  [cached]
Ayuga, Francisco
Informes de la Construccion , 1995,
Abstract: The design of silos has been the object of scientific and technical research for a whole century and this has led to great advances in the field. The results have not always been adequately disseminated among the technicians. The aim of this paper is to present the techniques for calculation of the loads of the materials stored in silos, inform about and comment on the standards, introduce the latest works carried out worldwide based on the finite elements method and, lastly, venture an opinion on the changes this may cause in the future. Durante un siglo el cálculo de silos ha sido objeto de investigación científica, técnica y aplicada y se han producido grandes avances. Todo este desarrollo no siempre ha sido bien dado a conocer entre los técnicos. El objeto de este artículo es precisamente presentar las técnicas de cálculo de acciones del material almacenado en silos, presentar y comentar la normativa, introducir los últimos trabajos que en el cálculo de silos se están haciendo en todo el mundo basados en la técnica de los elementos finitos y aventurar los cambios que esto va a suponer en un futuro.
Force networks and elasticity in granular silos  [PDF]
John F. Wambaugh,Robert R. Hartley,Robert P. Behringer
Physics , 2008,
Abstract: We have made experimental observations of the force networks within a two-dimensional granular silo similar to the classical system of Janssen. Models like that of Janssen predict that pressure within a silo saturates with depth as the result of vertical forces being redirected to the walls of the silo where they can then be carried by friction. By averaging ensembles of experimentally-obtained force networks in different ways, we compare the observed behavior with various predictions for granular silos. We identify several differences between the mean behavior in our system and that predicted by Janssen-like models: We find that the redirection parameter describing how the force network transfers vertical forces to the walls varies with depth. We find that changes in the preparation of the material can cause the pressure within the silo to either saturate or to continue building with depth. Most strikingly, we observe a non-linear response to overloads applied to the top of the material in the silo. For larger overloads we observe the previously reported "giant overshoot" effect where overload pressure decays only after an initial increase [G. Ovarlez et al., Phys. Rev. E 67, 060302(R) (2003)]. For smaller overloads we find that additional pressure propagates to great depth. This effect depends on the particle stiffness, as given for instance by the Young's modulus, E, of the material from which the particles are made. Important measures include E, the unscreened hydrostatic pressure, and the applied load. These experiments suggest that when the load and the particle weight are comparable, particle elasticity acts to stabilize the force network, allowing non-linear network effects to be seen in the mean behavior.
S'accabadora: viaggio nella terra del vento.  [cached]
Roberta Murroni
Altre Modernità , 2010,
Abstract: S'accabadora: viaggio nella terra del vento. Con testi dell'autrice. (Giovanna Mulas, Accabadora (Nessuno doveva sapere, nessuno doveva sentire) Como - Il Ciliegio, in coll. Con Acco Editore, 2010, con illustrazioni a colori e b/n di Pinna Podestà, 112 pp.) di Roberta Murroni
New steps towards the knowledge of silos behaviour
Ayuga F.,Aguado P.,Gallego E.,Ram???-rez A
International Agrophysics , 2005,
Abstract: The structural complexity of silos has been object of interest for engineers and researchers for more than a century. During years, mathematical models have tried to describe the problem with as less simplification as possible. Meanwhile, experimental tests in silos have been conducted in order to simulate reality. Phenomena are not yet well understood, but researchers have better analysis tools every year. The Spanish research team is now trying to provide some relevant result to the international community of silos researchers. This is the reason why finite element models are being improved. The filling and discharge phenomena as much as eccentricity influence are simulated to better understanding the silo behaviour. Commercial computer software with high capacities have been chosen to get an accurate simulation of the mechanical behaviour of the bulk solid, the silo wall, the contact between them and the dynamics of the phenomena. At the same time, difficulties have been found to apply these models due to the lack of knowledge existing about the mechanical parameters of the bulk materials that are required by the theoretical models. So an ambitious set of bulk materials tests have been designed to get such parameters with enough accuracy. Nowadays the simulation of silo explosions is not one of the research team objectives, however tests include determination of parameters of the bulk material related with the analysis of explosions, which anyway are necessary to a proper design of installations for protection and prevention. Finally, three experimental silos have been erected. They are cylindrical of 1.9 m in diameter and 5 m in height of the vertical wall, with emptying hoppers designed with three different eccentricities. The wall has been made of smooth steel, with enough thickness and reinforcements to be considered rigid. Specially designed sensors have been fixed in these silos, in order to measure the horizontal pressure and the friction force between the wall and the bulk solid. The horizontal pressure cells measure the deflection of a circular thin plate by means of four strain gauges, and the friction forces sensor measure the deformation of a small cantilever beam by two strain gauges. Although the research work is now in progress, the first results are hopeful and our research team wish to help in better understanding of these interesting structures.
Armazenamento de soja em silos tipo bolsa
Faroni, Lêda R. A.;Alencar, Ernandes R. de;Paes, Juliana L.;Costa, André R. da;Roma, Rafaela C. C.;
Engenharia Agrícola , 2009, DOI: 10.1590/S0100-69162009000100010
Abstract: this study reports major qualitative changes in the soybean grains and the extracted crude oil when stored in bag type silos. grains with moisture content of 17.4 or 13.3% were stored in two bag type silos. samples were taken 30, 90 and 180 days of storage , to determine moisture content, electric conductivity of the grain leachate, germination percentage, apparent specific grain mass, and free fatty acid content, and peroxide index of the crude oil extracted from these grains. the wet and dry grains remained with moisture contents similar to the original levels during the storage period. there was a tendency for to increase in the electric conductivity and decrease in the germination percentage of moist soybeans, especially after a ninety-day storage. the apparent grain density of moist or dry soybeans did not decrease. as regarding to the qualitative parameters of crude oil, the values remained below the legal limits required for marketing crude soybean oil. from the results it can be concluded that bag type silos represent a viable alternative for soybean storage without quality loss, and also storage in such structures does not lead to qualitative changes in the crude oil obtained from such grains.
Static avalanches and Giant stress fluctuations in Silos  [PDF]
P. Claudin,J. -P. Bouchaud
Physics , 1996, DOI: 10.1103/PhysRevLett.78.231
Abstract: We propose a simple model for arch formation in silos. We show that small pertubations (such as the thermal expansion of the beads) may lead to giant stress fluctuations on the bottom plate of the silo. The relative amplitude $\Delta$ of these fluctuations are found to be power-law distributed, as $\Delta^{-\tau}$, $\tau \simeq 1.0$. These fluctuations are related to large scale `static avalanches', which correspond to long-range redistributions of stress paths within the silo.
Vulnerabilidade de adolescentes no SILOS-Butant?
Soares, Cássia Baldini;ávila, Lívia Keismanas de;Salvetti, Marina de Góes;
Saúde e Sociedade , 1998, DOI: 10.1590/S0104-12901998000200006
Abstract: this study looks at vulnerability of adolescents who live in a s?o paulo city region: silos - butant?. it takes into account that: first, adolescents are social individuals whose development is determined by their life histories, according to their social status and their particular psychological development; second, that the social-illness process is socially determined and, therefore, adolescents' vulnerability to health problems is articulated with the work and life conditions of their families. the objective of this study is to characterize the social settings that allow and facilitate specific health problems of the adolescents. focusing the local health system (silos) of butanta - health assistance area of the university hospital - it was possible to establish a methodological trajectory to analyze secondary data from the districts of this area. the analysis shows that the district of raposo tavares -among all the disctricts of the area - is one of the territories that deserves to be under new investigations and health intervention especially for two reasons. first, it presents a larger number of gh-3 families (deficient way of life and work) and a smaller number of gh-1 families (adequate way of life and work) among the districts of the focused area. second: it was the district that received the worse punctuation in the exclusion/inclusion map of s?o paulo city.
Application of a discharge tubes in the grain silos (a technical note)
Kobielak S.,Shalouf F.F.
International Agrophysics , 1999,
Abstract: Dynamic pressures on the silo during the flow of materials is high and causes failure of silos. In this paper the authors desribe a device that reduces dynamic pressures and improves the flow of materials by means of a discharge tube.
Vigas preesforzadas con refuerzo externo  [cached]
Ferrer Narvaez Juan José
Ingeniería e Investigación , 1998,
Abstract: Es de gran interés para la ingeniería colombiana el efecto del refuerzo externo de elementos estructurales con elementos metálicos. La Unidad de Estructuras ha venido realizando en el transcurso de esta década estudios en elementos en concreto con refuerzos externos a flexión con resultados satisfactorios. El proyecto ''Vigas preesforzadas con refuerzo externo" sirve de base en el estudio del comportamiento de este tipo de elementos estructurales y la extrapolación de los resultados obtenidos en elementos de concreto reforzado a concreto preesforzado.
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