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Search Results: 1 - 10 of 154366 matches for " Valencia Clement Gabriel F. "
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Juntas en edificios de acero Joints in steel buildings
Valencia Clement Gabriel F.
Ingeniería e Investigación , 2006,
Abstract: Los elementos de mampostería y los miembros de acero usados en la construcción de edificios se mantienen en constante movimiento. Los cambios volumétricos son producto de las variaciones de temperatura y las deformaciones producidas por las cargas estáticas o dinámicas, y en algunos materiales, por los cambios en el contenido de humedad dentro de los mismos, tal el caso de la mampostería. El presente articulo está dirigido a la determinación de cuándo se requieren juntas de expansión o sísmicas, y como proporcionarlas y dise arlas con propiedad, específicamente en edificios de acero. No se incluye el estudio de las juntas en estructuras de concreto, en muros, ni otros elementos arquitectónicos. Masonry and steel components used in constructing buildings are in a constant state of motion. Volumetric changes are produced by temperature variation and deformation resulting from static or dynamic loading and in some materials, such as masonry, due to moisture content. This article addresses means of determining when expansion and seismic joints are required and how to proportion and design appropriate joints, specifically in steel buildings. It does not cover the study of expansion joints in concrete structures, in masonry construction or in non-structural (architectural) elements.
Evaluación del coeficiente de disipación de energía, R, para algunos tipos de estructuras de acero Evaluating response modification factor (R) for some types of steel structure
Valencia Restrepo Doralba,Valencia Clement Gabriel F.
Ingeniería e Investigación , 2008,
Abstract: En el presente artículo se cuestiona la validez del uso del coeficiente de disipación de energía tabulado en las Nor-mas Colombianas de Dise o y Construcción Sismorresistente, NSR-98, en la evaluación de las solicitaciones gene-radas por la acción del sismo de dise o en las estructuras de acero y las inconsistencias que se presentan al dimen-sionar la estructura para que cumpla derivas del 1%. Con tal fin se dise an 45 pórticos del sistema de resistencia sísmica de cinco edificios: 15 pórticos resistentes a momento (PRM), 15 pórticos arriostrados concéntricamente (PAC) y 15 pórticos arriostrados excéntricamente (PAE). El dise o se realiza de acuerdo con los requisitos de las NSR-98 en cuanto a solicitaciones (evaluación de cargas y combinaciones) y rigidez (1% de deriva) y a los requisitos de las provisiones sísmicas de AISC-2005 en cuanto a resistencia. Se evalúa el coeficiente de disipación de energía de los 45 pórticos para diferentes niveles de desempe o, por medio de plastificación progresiva modal, encontrán-dose que tal coeficiente no es constante para ninguno de los tres sistemas estructurales estudiados (PRM, PAC y PAE), tal como lo sugieren las NSR-98, y además los valores del coeficiente de disipación de energía hallados en la presente investigación son mucho menores a los tabulados en dichas normas, que rigen la práctica común del dise- o estructural, provocando graves errores en la evaluación de las solicitaciones de dise o, tanto de la estructura co-mo de los elementos de soporte (placas de base, fundaciones, pantallas) y estructuras adosadas a los pórticos del sistema de resistencia sísmico. Response modification factor (R), tabulated in the Colombian Design Code as NSR-98, is used in this paper for eva-luating internal member forces produced by design earthquake action on steel structures and the inconsistencies pre-sent when designing structures when 1% drift limits must be complied with. The article presents the design of 45 frames corresponding to the seismic resistance system of 5 buildings: 15 special moment frames (SMF), 15 special concentrically-braced frames (CBF) and 15 eccentrically-braced frames (EBF). External loads and their combination were used in estimating internal loads and rigidity demands (1% drift) were evaluated in line with NSR-98 requi-rements. Member strength requirements were evaluated by using the AISC-2005 seismic provisions for steel structu-red buildings. Modal pushover analysis was used for evaluating the response modification factor for the 45 given frames at different structural performance levels. It was
Calificación de una conexión rígida de una viga I y una columna tubular rellena de concreto bajo la acción de cargas dinámicas
Uribe Vallejo,Maritza; Valencia Clement,Gabriel F.;
Ingeniería e Investigación , 2009,
Abstract: using prequalified connections during the structural design stage becomes increasingly necessary when developing structural engineering projects which include steel elements; this is so that the steel elements? appropriate behavior can be ensured according to the structural system and seismic demand. unfortunately, the international entities providing this type of information (i.e. fema) only have a limit series of prequalified connections and such series do not include rigid connections between steel beams and concrete filled tubular (cft) columns having an extended end plate, which has become a very widespread building practice in colombia. this paper describes the most important aspects of a study at the universidad nacional de colombia concerning the behavior of a steel beam rigidly connected to a cft-column, using six physical models having different width-thickness ratio (b/t) columns. ansys v.10 software was used for studying theoretical models (finite elements analysis) for comparative analysis of cyclic test theoretical and experimental results for each specimen presented for the qualification phase. the six tested specimens? hysteretic curves are presented. several conclusions are drawn concerning finite element validation for this type of connection and the influence of width-thickness ratio (b/t) variation and design recommendations for suitable behavior under dynamic loads when this type of connection was used.
Calificación de una conexión rígida de una viga I y una columna tubular rellena de concreto bajo la acción de cargas dinámicas Evaluating a steel beam’s rigid connection to a concrete filled tubular column when submitted to dynamic load
Uribe Vallejo Maritza,Valencia Clement Gabriel F.
Ingeniería e Investigación , 2009,
Abstract: En el desarrollo de proyectos de ingeniería estructural que comprometen elementos de acero, cada día se hace más necesaria la posibilidad de emplear en la etapa de dise o conexiones precalificadas que garanticen el adecuado comportamiento requerí-do por los elementos estructurales, de acuerdo con el sistema estructural y las demandas sísmicas. Desafortunadamente, las en-tidades internacionales que suministran este tipo de información a nivel mundial, como FEMA, actualmente sólo cuentan con u-na serie limitada de conexiones precalificadas, dentro de las cuales no se encuentran incluidas las conexiones rígidas emperna-das de una viga I y una columna tubular rellena de concreto con placa extendida, práctica constructiva que recientemente ha ganado gran importancia en Colombia. El presente artículo describe los aspectos más sobresalientes del estudio del comporta-miento de una conexión rígida de una viga I y una columna tubular rellena de concreto, materializada en seis modelos físicos con variación en la relación ancho-espesor (b/t) de las columnas, que se realizó en la Universidad Nacional de Colombia. La calificación contempla el desarrollo de modelos teóricos-matemáticos empleando el método de los elementos finitos mediante la aplicación Ansys v.10, para efectuar un análisis comparativo de los resultados teóricos con los obtenidos experimentalmente al realizar los ensayos cíclicos de carga para cada espécimen. Así mismo, se presentan las curvas de histéresis de los seis especí-menes ensayados. Finalmente, se plantean varias conclusiones, entre otras, la validación del análisis por elementos finitos para estructuras con este tipo de conexión y la influencia de la variación en la relación ancho-espesor (b/t) de las columnas, y algu-nas recomendaciones de dise o que garanticen un comportamiento adecuado ante cargas dinámicas cuando se utilice el tipo de conexión estudiada. Using prequalified connections during the structural design stage becomes increasingly necessary when developing structural en-gineering projects which include steel elements; this is so that the steel elements’ appropriate behavior can be ensured according to the structural system and seismic demand. Unfortunately, the international entities providing this type of information (i.e. FEMA) only have a limit series of prequalified connections and such series do not include rigid connections between steel beams and concrete filled tubular (CFT) columns having an extended end plate, which has become a very widespread building practice in Colombia. This paper describes the most important aspe
Juntas en edificios de acero
Valencia Clement,Gabriel;
Ingeniería e Investigación , 2006,
Abstract: masonry and steel components used in constructing buildings are in a constant state of motion. volumetric changes are produced by temperature variation and deformation resulting from static or dynamic loading and in some materials, such as masonry, due to moisture content. this article addresses means of determining when expansion and seismic joints are required and how to proportion and design appropriate joints, specifically in steel buildings. it does not cover the study of expansion joints in concrete structures, in masonry construction or in non-structural (architectural) elements.
Evaluación del coeficiente de disipación de energía, R, para algunos tipos de estructuras de acero
Valencia Restrepo,Doralba; Valencia Clement,Gabriel;
Ingeniería e Investigación , 2008,
Abstract: in this paper the use of the response modification factor, r, as tabulated in the colombian design code, nsr-98, and many other design codes, in the evaluation of the internal member forces generated for the action of the design earthquakes in steel structures and the inconsistencies that are present when designing structures when it is necessary to comply drift limits of 1% are questioned. the design of 45 frames corresponding to the seismic resistance system of 5 buildings, that is, 15 special moment frames (prm), 15 special concentrically braced frames (pac) and 15 eccentrically braced frames (pae are presented). the external load evaluation and their combination used in estimating internal loads, as well as rigidity demands (1% drift) were made according to nsr-98 requirements, on the other hand, member strength requirements was evaluated using the seismic provisions for structural steel buildings, aisc-2005. the response modification factor of the 45 frames to different structural performance levels is evaluated, by means of modal pushover analysis. it has been found that this factor is not constant for any of the three structural systems (prm, pac and pae) as nsr-98 suggest and additionally the values of the response modification factor found in the present investigation, are smaller to those tabulated in this design code, which govern the common practice of the structural design; leading to significant errors in the evaluation of the design forces, not only in the structure but on the support elements (base plates, foundations, shear walls) and structures attached to the seismic resistance system.
Síndrome de Charles Bonnet: Manejo con haloperidol en paciente nonagenaria. Caso clínico
Valencia,Camila; Franco,José Gabriel;
Revista médica de Chile , 2008, DOI: 10.4067/S0034-98872008000300010
Abstract: charles bonnet syndrome is an underrecognized condition characterized by complex visual hallucinations, ocular problems causing visual deterioration and preserved cognitive status. its prevalence is 5/1000 in ambulatory ophthalmologic patients. generally occurs in elderly people in whom it may be confused with delirium or dementia. the first management step is to improve vision, if possible. hallucinations may be managed pharmacologically. we report a 94 year-old woman with the characteristic clinical picture of the syndrome that improved with haloperidol
Síndrome de Charles Bonnet: Manejo con haloperidol en paciente nonagenaria. Caso clínico Charle Bonnet syndrome: Report of one case managed with haloperidol
Camila Valencia,José Gabriel Franco
Revista médica de Chile , 2008,
Abstract: Charles Bonnet syndrome is an underrecognized condition characterized by complex visual hallucinations, ocular problems causing visual deterioration and preserved cognitive status. Its prevalence is 5/1000 in ambulatory ophthalmologic patients. Generally occurs in elderly people in whom it may be confused with delirium or dementia. The first management step is to improve vision, if possible. Hallucinations may be managed pharmacologically. We report a 94 year-old woman with the characteristic clinical picture of the syndrome that improved with haloperidol
Clinico-Epidemiological Pattern and Treatment of Epistaxis in a Tertiary Hospital in South Western Nigeria  [PDF]
Waheed Atilade Adegbiji, Gabriel Toye Olajide, Fatai Olatoke, Clement Chukwuemeka Nwawolo
International Journal of Otolaryngology and Head & Neck Surgery (IJOHNS) , 2018, DOI: 10.4236/ijohns.2018.73012
Abstract: Background/Objectives: Epistaxis is a common presentation and may constitute a major challenge to the parents and the health care givers. This study aimed at determining the clinico-epidemiological pattern, presentation and etiology of epistaxis. Materials and Methods: This prospective study of all patients that presented with epistaxis via the Ear, Nose and Throat department of a tertiary institution in Nigeria. The study was carried out between June 2012 and July 2017. Data were obtained from patients who gave consent by using pre-tested interviewer assisted questionnaire. All the data obtained were analyzed using SPSS version 16.0. Results: The prevalence of epistaxis in this study was 12.2%. The peak age group was 1-10 years with epistaxis prevalence of 36.4%. The male to female ratio was 1.5:1. Anterior epistaxis was more common than posterior epistaxis accounted for 80.1% and 7.4% respectively. Single episode of epistaxis was seen in 78.4% of the patients while recurrent epistaxis occurred in 21.6%. Unilateral epistaxis was 62.5%, bilateral epistaxis was 37.5% while right nasal bleeding accounted for 35.8%. The main local causes of epistaxis were trauma 29.5%, infective rhinosinusitis 18.8% and sinonasal tumours 12.5%. Severe epistaxis requiring blood transfusion was seen in 2.8% of the patients and death was recorded in 2.3%. Majority 110 (62.5%) were managed by observation alone, 20 (11.4%) by conservative therapy and 22 (12.5%) had surgical excision. Blood transfusion was given in 5. The outcome of treatment was good recovery in 79.0% while patients’ satisfaction with treatment was noted in 84.1%. Conclusion: Epistaxis is a common sinonasal presentation with effect on quality of life. In our center commonest site of nose bleeds was local mainly from traumatic, inflammatory and neoplastic aetiology.
Children and Poverty-Some Comments on I. Galli and R. Fasanelli
Valencia, Jose, F.
Papers on Social Representations , 1994,
Abstract:
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