2007, vol. 23, núm. 3
http://hdl.handle.net/2099/10362
2024-03-29T04:44:20ZAnálisis computacional del pandeo de paneles cilíndricos bajo presión uniforme
http://hdl.handle.net/2099/10412
Análisis computacional del pandeo de paneles cilíndricos bajo presión uniforme
Sosa, Eduardo M.; Godoy, Luis A.
En este trabajo se investiga una metodología de energía reducida para calcular el límite inferior de carga de pandeo de paneles cilíndricos rebajados. La formulación de esta nueva metodología está basada en los
postulados establecidos en la literatura para el cálculo de límites inferiores de carga de pandeo y se ha implementado en un programa de elementos finitos de aplicaciones múltiples. Se han analizado paneles formados de material isotrópico y caracterizados por tres valores del parámetro de Batdorf. De la comparación de los resultados obtenidos con la metodología propuesta con aquellos obtenidos de análisis no lineales incluyendo diferentes niveles de imperfección geométrica, surge que el modelo de energía reducida aplicado a paneles
cilíndricos no conduce a límites inferiores de carga de pandeo. Si bien este nuevo modelo de energía reducida predice cargas de pandeo inferiores a las obtenidas del análisis clásico, éstas son mayores que las obtenidas de análisis no lineales. Sin embargo, la viabilidad de la implementación de una metodología de energía reducida en un programa de elementos finitos de aplicaciones múltiples queda demostrada.
2011-06-01T14:56:45ZSosa, Eduardo M.Godoy, Luis A.En este trabajo se investiga una metodología de energía reducida para calcular el límite inferior de carga de pandeo de paneles cilíndricos rebajados. La formulación de esta nueva metodología está basada en los
postulados establecidos en la literatura para el cálculo de límites inferiores de carga de pandeo y se ha implementado en un programa de elementos finitos de aplicaciones múltiples. Se han analizado paneles formados de material isotrópico y caracterizados por tres valores del parámetro de Batdorf. De la comparación de los resultados obtenidos con la metodología propuesta con aquellos obtenidos de análisis no lineales incluyendo diferentes niveles de imperfección geométrica, surge que el modelo de energía reducida aplicado a paneles
cilíndricos no conduce a límites inferiores de carga de pandeo. Si bien este nuevo modelo de energía reducida predice cargas de pandeo inferiores a las obtenidas del análisis clásico, éstas son mayores que las obtenidas de análisis no lineales. Sin embargo, la viabilidad de la implementación de una metodología de energía reducida en un programa de elementos finitos de aplicaciones múltiples queda demostrada.Otimização da rigidez de ligações resistentes a momento fletor utilizando algoritmo genérico
http://hdl.handle.net/2099/10366
Otimização da rigidez de ligações resistentes a momento fletor utilizando algoritmo genérico
Rodrigo Carreira, Mercelona; Guelbert, Marcelo
The heuristic methods are a powerful tool for the optimization of complex problems. The genetic algorithms are the heuristic methods of larger prominence in the optimization of enginnergin problems. This paper presents the implementation and the test of a program in C++ language for the optimization of bolted connections in wood members. For the wood, the EUROCODE 5 design method were used and for the steel plates were used EUROCODE 3. Twelve simulations were accomplished and the program presented good convergence for connections using steel plates as connection element.
2011-05-06T18:30:56ZRodrigo Carreira, MercelonaGuelbert, MarceloThe heuristic methods are a powerful tool for the optimization of complex problems. The genetic algorithms are the heuristic methods of larger prominence in the optimization of enginnergin problems. This paper presents the implementation and the test of a program in C++ language for the optimization of bolted connections in wood members. For the wood, the EUROCODE 5 design method were used and for the steel plates were used EUROCODE 3. Twelve simulations were accomplished and the program presented good convergence for connections using steel plates as connection element.Detección de anomalías 2D por un método de inversión tomográfica por mínima dispersión
http://hdl.handle.net/2099/10365
Detección de anomalías 2D por un método de inversión tomográfica por mínima dispersión
Calvo, Carlos Adolfo; Imhof, Armando Luis
Existen numerosos métodos de inversión por la técnica de tomografía en tiempo de viaje. En este trabajo se desarrolló un procedimiento original para la determinación de anomalías convexas, homogéneas e isotrópicas en un medio con las mismas dos últimas características. Los emisores, receptores y la inclusión ubicados en forma arbitraria en un dominio bi-dimensional. Se hace uso de un criterio de mínima dispersión que conduce a un sistema lineal de ecuaciones. La experimentación numérica muestra la validez del método en lo que respecta a la ubicación, forma y tamaño de la anomalía.
2011-05-06T17:46:35ZCalvo, Carlos AdolfoImhof, Armando LuisExisten numerosos métodos de inversión por la técnica de tomografía en tiempo de viaje. En este trabajo se desarrolló un procedimiento original para la determinación de anomalías convexas, homogéneas e isotrópicas en un medio con las mismas dos últimas características. Los emisores, receptores y la inclusión ubicados en forma arbitraria en un dominio bi-dimensional. Se hace uso de un criterio de mínima dispersión que conduce a un sistema lineal de ecuaciones. La experimentación numérica muestra la validez del método en lo que respecta a la ubicación, forma y tamaño de la anomalía.Modelagem estocástica do comportamento dinâmico de tabuleiros rodoviários submetidos ao tráfego de veículos
http://hdl.handle.net/2099/10364
Modelagem estocástica do comportamento dinâmico de tabuleiros rodoviários submetidos ao tráfego de veículos
Santos de Almeida, Ricardo; Santos da Silva, José Guilherme
In this paper an analysis methodology is developed to evaluate the dynamic response on highway bridge decks due to vehicles crossing on the rough pavement surfaces. The analysis methodology follows a statistical
model running in the time domain. The mathematical model simulates the bridge structure and the vehicle series as a system, the vehicle-bridge system. The bridge deck follows a straight beam model made discrete by finite elements and nodal concentrated masses, with vertical translations and in-plane rotations as degrees of freedom. The vehicle simulation uses concentrated parameters of mass, stiffness and damping. Four different types of vehicles are modelled as rigid masses connected by springs and dampers with one, two, four or five degrees of freedom. According to each vehicle model, translational and rotational displacements
are considered. The deck surface roughness is defined by a weakly stationary, second order and ergodic random process based on a well-known power spectrum density of road pavement profiles. The moving load is modelled by an infinite series of equal vehicles, regularly spaced, and running at constant velocity. Only steady-state response is considered. Response data are produced on reinforced concrete highway bridge decks made of a straight box girder cross section based on several spans and support arrangements. Conclusions are concerned with the fitness of the developed analysis methodology and the mathematical model adequacy. The influence of the vehicle type on the highway bridge decks dynamic behaviour was observed. The magnitude of the effects due to the interaction of the vehicles with an irregular pavement surface and their consequences about design and maintenance are investigated.
2011-05-06T17:26:29ZSantos de Almeida, RicardoSantos da Silva, José GuilhermeIn this paper an analysis methodology is developed to evaluate the dynamic response on highway bridge decks due to vehicles crossing on the rough pavement surfaces. The analysis methodology follows a statistical
model running in the time domain. The mathematical model simulates the bridge structure and the vehicle series as a system, the vehicle-bridge system. The bridge deck follows a straight beam model made discrete by finite elements and nodal concentrated masses, with vertical translations and in-plane rotations as degrees of freedom. The vehicle simulation uses concentrated parameters of mass, stiffness and damping. Four different types of vehicles are modelled as rigid masses connected by springs and dampers with one, two, four or five degrees of freedom. According to each vehicle model, translational and rotational displacements
are considered. The deck surface roughness is defined by a weakly stationary, second order and ergodic random process based on a well-known power spectrum density of road pavement profiles. The moving load is modelled by an infinite series of equal vehicles, regularly spaced, and running at constant velocity. Only steady-state response is considered. Response data are produced on reinforced concrete highway bridge decks made of a straight box girder cross section based on several spans and support arrangements. Conclusions are concerned with the fitness of the developed analysis methodology and the mathematical model adequacy. The influence of the vehicle type on the highway bridge decks dynamic behaviour was observed. The magnitude of the effects due to the interaction of the vehicles with an irregular pavement surface and their consequences about design and maintenance are investigated.Alto desempenho: o concreto armado do século XXI?
http://hdl.handle.net/2099/10363
Alto desempenho: o concreto armado do século XXI?
Lorrain, Michel S.; Pinto Barbosa, Mônica; Arnaud, Maurice; Gamino, André Luis
This work is about the 21st century reinforced concrete analysis under the point of view of its constituent materials. First of all it is described the theoretical approach of the bending elements calculated based on the Norms BAEL 91 standarts. After that, numerical load-displacement are presented from reinforced concrete beams and plates validated by experimental data. The numerical modellings has been carried on
in the program CASTEM 2000. In this program a elastoplastic model of Drucker-Prager defines the rupture surface of the concrete in non associative plasticity. The crack is smeared on the Gauss points of the finite
elements with formation criterion starting from the definition of the rupture surface in the branch traction-traction of the Rankine model. The reinforcements were modeled in a discrete approach with perfect bond.
Finally, a comparative analysis is made between the numerical results and calculated criteria showing the future of high performance reinforced concrete in this beginning of 21st century.
2011-05-06T16:37:25ZLorrain, Michel S.Pinto Barbosa, MônicaArnaud, MauriceGamino, André LuisThis work is about the 21st century reinforced concrete analysis under the point of view of its constituent materials. First of all it is described the theoretical approach of the bending elements calculated based on the Norms BAEL 91 standarts. After that, numerical load-displacement are presented from reinforced concrete beams and plates validated by experimental data. The numerical modellings has been carried on
in the program CASTEM 2000. In this program a elastoplastic model of Drucker-Prager defines the rupture surface of the concrete in non associative plasticity. The crack is smeared on the Gauss points of the finite
elements with formation criterion starting from the definition of the rupture surface in the branch traction-traction of the Rankine model. The reinforcements were modeled in a discrete approach with perfect bond.
Finally, a comparative analysis is made between the numerical results and calculated criteria showing the future of high performance reinforced concrete in this beginning of 21st century.