A numerical approach for fault detection in beam-like structures using modal strain energy

Riveros, Carlos Alberto | 2013-12-16

La detección de daño estructural usando vibraciones se fundamenta en el hecho de que pueden usarse mediciones de cambios en las propiedades de vibración de una estructura para determinar la ocurrencia de daño estructural, por lo tanto, existe una fuerte necesidad de desarrollar e implementar métodos de detección de daño y óptima localización de sensores que tengan en cuenta el uso de instrumentación limitada y su efecto en la predicción de deterioro estructural. En este artículo se presentan los resultados de la implementación numérica de un método de óptima localización de sensores previamente desarrollado. Se ensambla un modelo en elementos finitos con base en un modelo de un puente ferroviario de tipo viga-cajón. Luego, el método de índice de daño se emplea para la identificación de daño estructural, con base en las mediciones obtenidas de los sensores. Los métodos de óptima localización de sensores y de detección de daño presentados en este artículo se basan en el uso de la energía modal de deformación. Los resultados numéricos muestran que la energía modal de deformación es apropiada para aplicaciones de seguimiento continuo de daño en estructuras y que puede usarse como una herramienta útil para inspecciones de integridad estructural en estructuras tipo viga.

Algoritmo de integración para materiales no lineales considerando los efectos de viscoplasticidad, endurecimiento cinemático no lineal y daño

Gómez-Cataño, J. D. (Juan David) | 2014-05-07

In the Finite Element Method (FEM) material non-linearities are considered through incremental formulations in terms of a pseudo-time variable for the case of rate independent models and a real time variable in the case of rate-dependent models. The incremental statement of the problem implies that the constitutive models need to be time-integrated at the local level. In this article we discuss a standard algorithm available in the literature where additionally we have incorporated the effects of non-linear kinematic hardening, viscoplasticity, and damage. The algorithm is incorporated into a FEM code. In order to verify the correctness of our implementation we have particularized the model to the case of a creep law available from literature for solder alloys. Numerical simulation results are compared with experiments taken from the literature.

Análisis del funcionamiento de plantas de manejo de residuos sólidos en el norte del Valle del Cauca, Colombia

Marmolejo, Luis Fernando | 2013-12-17

In Colombia, the acceptance of resource recovery is demonstrated through the high number of municipalities which have introduced this alternative in their integrated solid waste management plans, together with the increasing number of solid waste management facilities (SWMFs) that have been established. This situation also highlights the need for a comprehensive evaluation of the existing experiences as well as research and development around this topic. In this paper, the performance of five SWMFs located in municipalities in northern Valle del Cauca is analyzed. The analysis shows that, despite the fact that SWMFs have operational deficiencies, features such as markets for their products, employment generation and avoided costs in waste disposal in landfills show sufficient grounds for their continuity. Key elements to strengthen SWMFs performance are long-term awareness of service users, adaptation of technologies to the context, enhancement of managerial capacity and better support to resource recovery within the national political framework.

El barrio como sistema ecológico de grupos humanos

Gaviria-Gutiérrez, Z. (Zoraida) | 2015-10-08

Bolted timber joints with self-tapping screws

Echavarría-López, C. A. (César Augusto) | 2014-05-08

En este artículo se estudia el uso de tornillos autoperforantes como refuerzo para evitar rupturas frágiles en uniones de madera. Se presenta un modelo teórico para calcular la distribución de esfuerzos alrededor de un perno en una unión de madera, predecir las rupturas frágiles y evaluar el esfuerzo en los tornillos autoperforantes. Los experimentos de laboratorio con uniones de madera, con pernos de 15,9 mm de diámetro, reforzadas y no reforzadas mostraron la efectividad del modelo teórico propuesto.

Caracterización dinámica de una mezcla asfáltica sometida a las condiciones ambientales de Bogotá

Rondón-Quintana, Hugo Alexánder | 2013-11-21

The paper presents the evolution of the resilient modulus, permanent vertical deformation, and fatigue law of hot mix asphalt (HMA) when exposed to the weather conditions in the city of Bogotá D.C. (Colombia) for 29 months. The trend of mixture with the exposure time is to experience an increase in stiffness values, mainly due to age-hardening process of the asphalt binder. This increase in stiffness creates increased resistance to permanent deformation and decrease in fatigue life of the analyzed mixture. Based on the resilient modulus evolution with time of exposure to the environment an equation to predict approximately the change for the fatigue life of the mixture is proposed.

Características, dinámica y causas del movimiento en masa del Barrio El Socorro (31 de mayo de 2008) en Medellín

Aristizábal, E. (Edier) | 2014-05-12

The article presents the causes and dynamic of the mass movement which occurred on May 31, 2008 in the higher part of San Pedro settlement, called Las Peñitas, Medellín. This tragic event left 27 dead people, 16 injured people and 20 houses destroyed of El Socorro settlement. This event with Rosellón (1927), Media Luna (1954), Santo Domingo (1974), Villatina (1987) and El Barro (2005) represents one of the most tragic events in the Aburrá Valley history. For the characterization of the area of the event previous work from different recognized, prestigious institutions was used; for the characterization, description of the predominant dynamics of the event and its causes ground evidence collected on the terrain and visual inspection the same day when it occurred were used, so that it did not change due to proper rescue works. The data of rainfall hydrometeorological stations of Empresas Públicas de Medellín (EPM) and Colombian Institute of Hydrology, Meteorology and Environmental Studies (IDEAM) were used, with the purpose of evaluating the influence of rain like triggering element. The mass movement was classified as simple rotational landslide on NE direction, with a longitude around 60 m, which due to high saturation levels, it changed to an debris flow moving 140 m ahead on SE direction, and finally the mass turned NE. Triggering causes are associated to geomechanical properties of soil and antecedent rainfall of previous 15 days and very intense rainfall event during May 30, when 83.3 mm fell down for just 2 hours and 30 minutes along the central part of the valley.

Comportamiento mecánico y de fraguado de morteros de cemento Pórtland gris tipo III con aditivos

Montoya-Toro, Y. A. (Yirson Alberto) | 2013-11-27

In the present work the variability in the performance of mortars by using different batches of two types of additives, one retardant and one accelerant of setting was studied, for this purpose, their behavior was compared with a mortar without additive. The physical, mechanical, and chemical properties of the gray Portland cement type III from Cementos Rioclaro, the initial and final setting times using different doses of additive were measured; besides, compression strength tests of mortars with retardant additive were made. Between the additives batches studied a small variability was found; the retardant additive used with a content of 0,6 wt % of cement showed that as the higher initial setting time, final setting time is higher. Using the additive in doses up 0,6 % wt of cement and increase of the retard time around 550 y 600 min with the increase in the additive content. Similarly, with the increase of the retardant additive diminishes the initial strength and increases the final strength of the mortar. With growing doses of accelerant content additive diminished the setting time of the mixes studied.

Definición de un método basado en patrones de análisis para la interoperabilidad entre sistemas de información geográfica

Zapata, Carlos Mario | 2013-11-08

Geographic Information Systems (GIS) are incorporated in the companies to facilitate spatial analysis of the information. This analysis often requires the integration of GIS heterogeneous data to interoperate. In GIS, interoperability is mainly addressed by the specification of standards and the implementation of several mechanisms like ontologies, web services, grid computing, and middleware technologies. In order to implement any of such mechanisms, an analyst should make a detailed and iterative study of the GIS domain for every situation of interoperability is needed. Such study is, commonly, subjective and highly dependent on the analyst experience. Consequently, the entire process seems not to be transparent and traceable. For this reason, in this paper we propose an interoperability method for generalizing the analysis phase of the GIS domain. The method comprises seven steps supported by analysis patterns expressed in pre-conceptual schemas. The method can be integrated with the aforementioned mechanisms for interoperability, thus shortening the analysis phase and providing a communication channel between the user, the analyst, and the developer.

Determinación de las fracciones SARA de asfaltos colombianos envejecidos al medio ambiente empleando cromatografía líquida en columna

Reyes-Lizcano, Fredy Alberto | 2013-11-12

In this paper, we present a method based on liquid chromatography column to quantify the chemical composition of asphalt cements manufactured in Colombia, under the environment by determining the SARA fractions. The method was applied to thin layers of asphalt 60/70 and 80/100 to determine changes in the chemical composition of the material after exposure for 12 months in the weather conditions in the city of Bogotá; SARA tests were performed to the original asphalt, 1, 3, 6, 9 and 12 months aged respectively. SARA trials showed that aging caused a decrease in the fraction of aromatics and asphaltenes increased compared to non-aged asphalt. The reduction of aromatics and resins could be responsible for the hardening observed in the asphalt, which had a stiff and brittle consistency; that leads to obtaining higher colloidal index. The performed method established possible correlations between the chemical composition of asphalt and its mechanical properties

Directrices de intervención sobre el espacio público: quebrada La Mansión, Comuna 8 de Medellín

González-Martínez, L. F. (Luis Fernando) | 2014-05-13

This paper proposes the guidelines that should lead to the eventual development of the project of the La Mansion Neighborhood Park, towards the consolidation of an urban park that will act as a reference of a neighborhood, zone connector and supplier of public space for the Commune 8 within the concepts of social inclusion and environmental conservation.

Diseño de mezclas de suelo compactado para la construcción de terraplenes

Aiassa, G. (Gonzalo) | 2014-05-08

The highways or airfield pavement performance depends on the material behavior in different structural layers of embankment. Generally, economic limitations force to use of in situ available soil as material for pavement construction. The improvement of soil by compaction and mixture with granular or stabilizing material is an adequate strategy. In this work, a study of mechanical behavior of silty-sand soil has been made, and the aptitude of use it as sub-base material has been evaluated. The soil analyzed corresponds to superficial layers in the central region of Argentina (southern zone of Cordoba province). The mechanical characterization has been made in laboratory, with unconfined compression and CBR tests on compacted soil-cement and soil-granular material. The results has shown materials characterization and concluding of the use and performance on compacted soil sub-base pavements construction.

Disipadores histeréticos metálicos como técnica de control de respuesta sísmica en edificaciones colombianas

Oviedo, J. A. (Juan Andrés) | 2013-11-27

This paper presents a qualitative analysis of the possibility of implementing seismic response control techniques in buildings in Colombia. Given the current local conditions in engineering and construction in the country, herein are presented the main reasons why it is considered that the passive control of structures would be the most suitable technique to be implemented in Colombia. Desirable features on the fabrication and application of metallic energy dissipators are exposed, and metallic buckling-restrained braces (BRB) dissipators are presented as one viable option for the protection and control for structural damage of buildings in the country.

Equipamiento urbano en el sector educativo del municipio de Envigado

Gómez-Herrera, J. M. (Juan Mauricio) | 2014-05-12

This document portrays the current situation of urban equipment in the municipality of Envigado in the education sector, specifically in reference to its occupation. It begins with the international agreements that has subscribed Colombia. It has into account the Colombian Political Constitution which guarantees the right of children and youngsters to basic education and the obligation of the government to fulfill this right; it follows with the policy established by the last two local Government’s Development Plans, from 2003 to 2006 (education policy, infrastructure and operation investment, coverage, transfers from the national government, allocations by students according to the General Contributions System and municipal expenses by student); then, the occupation of all educational public institutions in relation with their installed capacity is assessed, evaluating the growth of student population in each institution and in the zone in which they are located, compared with the population growth in the aforementioned zones; lastly, and based on the previous evaluations, several conclusions are drawn and some recommendations, made.

Estimación de modelos lineales para el control predictivo de pequeñas centrales hidroeléctricas

Estrada-Viana, I. D. (Iván Darío) | 2014-05-14

This paper presents the modeling of a Small Hydroelectric Plant (PCH), by obtaining linear prediction models. The mathematical model of the system, provides all your hydraulic system, which runs from the reservoir tank, through the tunnel for the transport of water resources, load lines, up to the generation units. Subsequently, the system proceeds to modeling, using a set of prediction models like ARX models, ARMA X, Box-Jenkins and Output Error (OE). The results obtained for each of the above models were evaluated versus nonlinear dynamic model that represents the dynamic behavior of the system. This evaluation was based on error analysis and according to the performance index of each model. Thus, the best results were obtained by the OE model as this shows a direct way as the error may affect the system output. Finally, the development of this model can be used in the implementation of predictive controllers for load distribution (power generation) in Small Hydroelectric Plant, based on the conditions of water availability in the reservoir tank.

Evaluation of HMA cracking resistance as a function of laboratory aging based on the direct-tension test

Walubita, Lubinda F. | 2013-11-13

La mezcla asfáltica en caliente (MAC) es un material compuesto, heterogéneo, integrado por cemento asfáltico (o asfalto), agregados, vacíos y otros aditivos incluyendo cal, fibras, etc., usado predominantemente para la construcción de pavimentos. A lo largo del tiempo, la MAC sufre envejecimiento, lo cual conlleva cambios en las propiedades del material y en su respuesta. Este artículo documenta un estudio de laboratorio llevado a cabo para evaluar la posibilidad de emplear el ensayo de tensión directa (TD) para determinar los efectos del envejecimiento del asfalto sobre las propiedades de fractura y resistencia al agrietamiento de MAC. Dos MAC de gradación densa fueron sometidas a diferentes condiciones de envejecimiento en laboratorio y luego sometidas al ensayo de TD. A partir de este ensayo, el comportamiento ante fractura se caracterizó en términos de la resistencia a tensión, deformación unitaria de tensión a la carga de falla, rigidez y energía de fractura. En general, los resultados indicaron que el envejecimiento por oxidación del asfalto tiene un efecto negativo sobre la respuesta ante fractura y la resistencia al agrietamiento de la MAC, el cual puede ser captado por medio del ensayo de TD. Por lo tanto, el envejecimiento del asfalto debe ser considerado y cuantificado en forma adecuada durante el diseño y análisis de la MAC. Sin embargo, se recomienda adelantar investigación adicional con otras mezclas y correlacionar resultados con datos de campo para validar la información de laboratorio reportada en este artículo.

La expansión urbana sobre las periferias rurales del entorno inmediato a la ciudad metropolitana

Gaviria-Gutiérrez, Z. (Zoraida) | 2014-05-13

The urban expansion on the rural peripheries is a phenomenon of world-wide occurrence, treated by diverse authors. To this situation the great metropolitan city of the Valley of Aburrá does not escape, expressed in the presence of rustic and semirustic urbanizations, and commercial enclaves and of services in countryside of its immediate surroundings, which cause multiple impacts in the development and quality of life of the population of the central region of Antioquia. In the paper considerations on this phenomenon are presented around three aspects: the correspondence of this form of occupation of land with the model of city wished and defined in the POT (territorial ordering plan); the coherence in the definition of the urban, suburban, rural zones, those of expansion and protection, with the model of city and the norms regulating the suburban and rural areas; finally, the possible impacts of this process of suburbanization are exposed, in the different aspects of territorial development.

La función fuerza específica en canales

Mejía-Garcés, F. J. (Francisco Jaime) | 2014-05-06

This paper shows the momentum equation applied to open-channel flow and to study the specific force function in terms of its properties, the definition of a critical flow condition and its non-dimensional form.

Gestión de Proyectos con Teoría de Restricciones aplicada al área técnica de la Compañía Construcciones y Servicios S. A.

Gómez-Posada, L. F. (Luis Felipe) | 2014-05-13

The Dinpro-Construcciones y Servicios group is oriented towards the design, construction, assembly and maintenance of industrial and logistic projects; “Construcciones y Servicios” company focuses in the construction, assembly, and maintenance of these projects; this article is developed at this company. One of the most important activities within the execution of construction projects is to ensure that the contractors are well prepared to execute that which was agreed, in the scheduled moment and with the arranged characteristics, but to hire on time before the starting day of the each activity depends of the work team. Nevertheless, there are no follow up and control tools which allow assuring the efficacy of the hiring process so that it is done on time in the field. This essay pretends to display the experience of “Construcciones y Servicios” S.A. in the application of the solutions granted elements for the General Management of TOC Projects (Critical chain) to the hiring process, executed as a project per se with successful results.

Gestión estratégica de la arborización urbana: beneficios ecológicos, ambientales y económicos a nivel local y global

Molina-Prieto, L. F. (Luis Fernando) | 2014-05-14

The article approaches the urban tree planting issue emphasizing on the variety of ecological, environmental and economic welfare it brings to the city, its inhabitants and the whole planet when managed strategically, such as, pollution and noise decrease, urban microclimate improvement, global warming mitigation, water levels regulation, soil fertilization and native bird populations conservation —both from endemic and migratory species—, among other global and local notable benefits. It also analyzes the negative impact that an incorrect tree planting management causes on urban infrastructure, as well as the high expenditure it represents to repair. It concludes, amid the aforementioned, that faulty planning of urban tree planting is harmful to city’s public resources and so to their sustainability, besides actually escalating global warming.