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Análise estrutural de galpões atirantados de concreto pré-moldado; Structural analysis of sheds with tied portal frames of precast concrete

Santos, Andreilton de Paula
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 08/06/2010 PT
Relevância na Pesquisa
46.45%
Os galpões de concreto pré-moldado, formados por pórticos atirantados, são muito utilizados, no Brasil. Porém, para o projeto dessas estruturas, a bibliografia é limitada. Além disso, vários critérios de projeto são adaptados dos relativos a estruturas de concreto moldado no local e de múltiplos pavimentos. O objetivo deste trabalho é contribuir para a análise desse tipo de estrutura, introduzindo conceitos que dificilmente são considerados na prática, tais como: rigidez da ligação viga-pilar, análise não-linear física e geométrica, deformação excessiva e fluência. A pesquisa foi desenvolvida por meio de análises estruturais, usando modelos de galpões comuns na prática. Cada conceito citado anteriormente foi analisado em exemplos. A rigidez da ligação viga-pilar foi avaliada com base no parâmetro de restrição à rotação, 'alfa'R. A não-linearidade física (NLF) do concreto foi considerada pelo método de Branson. Para a não-linearidade geométrica (NLG), foram utilizados os parâmetros 'alfa' e o processo P.'delta'. A deformação excessiva, incluindo a fluência, foi discutida tendo em conta os aspectos normativos. Constatou-se que a ligação viga-pilar pode ter comportamento semi-rígido em alguns casos...

Estudo de uma estrutura em pórtico para utilização em um veículo agrícola autônomo; Study of a portal frame structure for use in an autonomous agriculture vehicle

Freitas, Rafael Rodrigues de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/05/2008 PT
Relevância na Pesquisa
66.43%
Avanços nas pesquisas em Veículos Agrícolas Autônomos (VAA's) e de Robôs Agrícolas Móveis (RAM's) têm sido conquistados nos últimos anos. Entretanto, um número limitado de trabalhos foca o desenvolvimento das estruturas destes veículos. O presente trabalho apresenta uma revisão de materiais encontrados na literatura e no mercado. Estudou-se modelagem cinemática de veículos autônomos que possuem configurações de suas estruturas projetadas para ter mobilidade melhorada. Estudaram-se estruturas mecânicas de máquinas que atuam em vários estádios de desenvolvimento de lavouras típicas brasileiras. Baseado no levantamento e esse estudo, foi projetado e construído um veículo com conceito modular e de pórtico para ser uma plataforma robótica no qual é utilizado para o sensoriamento em área agrícola. Uma modelagem cinemática simplificada do veículo foi realizada, fundamentada nos conceitos básicos de cinemáticas em robôs móveis. Por fim é apresentado o desenvolvimento da estrutura em pórtico do veículo. Pretende-se que o resultado auxilie no desenvolvimento de projeto de VAA's.; Advance on AAV (Autonomous Agriculture Vehicle) and MAR (Mobile Agriculture Robots) research are noticed in the recent years. However...

On the dynamics of free and excited oscillations of a simple portal frame foundation

Dantas, MJH; Balthazar, José Manoel
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 541-557
ENG
Relevância na Pesquisa
36.02%
In this paper we search for the dynamics of a simple portal structure in the free and in the periodic excitation cases. By using the Center Manifold approach and Averaging Method, we obtain results on both stability and bifurcation of equilibrium points and periodic orbits. (C) 2005 Elsevier Ltd. All rights reserved.

On saturation control of a non-ideal vibrating portal frame foundation type shear-building

Felix, JLP; Balthazar, José Manoel; Brasil, RMLRF
Fonte: Sage Publications Ltd Publicador: Sage Publications Ltd
Tipo: Artigo de Revista Científica Formato: 121-136
ENG
Relevância na Pesquisa
66.43%
In this paper, we examine the nonlinear control method based on the saturation phenomenon and of systems coupled with quadratic nonlinear ties applied to a shear-building portal plane frame foundation that supports an unbalanced direct cut-rent with limited power supply (non-ideal system). We analyze the equations of motion by using the method of averaging and numerical simulation. The interaction of the non-ideal structure with the saturation controller may lead to the occurrence of interesting phenomena during the forward passage through the several resonance states of the systems. Special attention is focused on passage through resonance when the non-ideal excitation frequency is near the portal frame natural frequency and when the non-ideal system frequency is approximately twice the controller frequency (two-to-one internal resonance).

Short comments on self-synchronization of two non-ideal sources supported by a flexible portal frame structure

Balthazar, José Manoel; Felix, JLP; Brasil, RMLRF
Fonte: Sage Publications Ltd Publicador: Sage Publications Ltd
Tipo: Artigo de Revista Científica Formato: 1739-1748
ENG
Relevância na Pesquisa
56.33%
A practical problem of synchronization of a non-ideal (i.e. when the excitation is influenced by the response of the system) and non-linear vibrating system was posed and investigated by means of numerical simulations. Two rotating unbalanced motors compose the mathematical model considered here with limited power supply mounted on the horizontal beam of a simple portal frame. As a starting point, the problem is reduced to a four-degrees-of-freedom model and its equations of motion, derived elsewhere via a Lagrangian approach, are presented. The numerical results show the expected phenomena associated with the passage through resonance with limited power. Further, for a two-to-one relationship between the frequencies associated with the first symmetric mode and the sway mode, by using the variation of torque constants, the control of the self-synchronization and synchronization (in the system) are observed at certain levels of excitations.

On non-ideal simple portal frame structural model: Experimental results under a non-ideal excitation

Balthazar, José Manoel; Brasil, RMLRF; Garzeri, F. J.; Lucas, M.
Fonte: Trans Tech Publications Ltd Publicador: Trans Tech Publications Ltd
Tipo: Conferência ou Objeto de Conferência Formato: 51-57
ENG
Relevância na Pesquisa
46.16%
We present measurements of the non-linear oscillations of a portal frame foundation for a non-ideal motor. We consider a three-time redundant structure with two columns, clamped in their bases and a horizontal beam. An electrical unbalanced motor is mounted at mid span of the beam. Two non-linear phenomena are studied: a) mode saturation and energy transfer between modes; b) interaction between high amplitude motions of the structure and the rotation regime of a real limited power motor. The dynamic characteristics of the structure were chosen to have one-to-two internal resonance between the anti-symmetrical mode (sway motions) and the first symmetrical mode natural frequencies. As the excitation frequency reaches near resonance conditions with the 2nd natural frequency, the amplitude of this mode grows up to a certain level and then it saturates. The surplus energy pumped into the system is transferred to the sway mode, which experiences a sudden increase in its amplitude. Energy is transformed from low amplitude high frequency motion into high amplitude low frequency motion. Such a transformation is potentially dangerous.We consider the fact that real motors, such as the one used in this study, have limited power output. In this case...

On non-ideal and non-linear portal frame dynamics analysis using Bogoliubov averaging method

Palacios, J. L.; Balthazar, José Manoel; Brasil, R. M L R F
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 257-265
ENG
Relevância na Pesquisa
56.33%
We apply the Bogoliubov Averaging Method to the study of the vibrations of an elastic foundation, forced by a Non-ideal energy source. The considered model consists of a portal plane frame with quadratic nonlinearities, with internal resonance 1:2, supporting a direct current motor with limited power. The non-ideal excitation is in primary resonance in the order of one-half with the second mode frequency. The results of the averaging method, plotted in time evolution curve and phase diagrams are compared to those obtained by numerically integrating of the original differential equations. The presence of the saturation phenomenon is verified by analytical procedures.

On Nonlinear Dynamics and Control of A Particular Portal Frame Foundation Model, Excited by a Non-Ideal Motor

Balthazar, José Manoel; Felix, Jorge Luis Palacios; Brasil, Reyolando Manoel Lopes Rabelo da Fonseca
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 371-378
ENG
Relevância na Pesquisa
66.38%
The nonlinear dynamic response and a nonlinear control method of a particular portal frame foundation for an unbalanced rotating machine with limited power (non-ideal motor) are examined. Numerical simulations are performed for a set of control parameters (depending on the voltage of the motor) related to the static and dynamic characteristics of the motor. The interaction of the structure with the excitation source may lead to the occurrence of interesting phenomena during the forward passage through the several resonance states of the systems. A mathematical model having two degrees of freedom simplifies the non-ideal system. The study of controlling steady-state vibrations of the non-ideal system is based on the saturation phenomenon due to internal resonance.

Nonlinear dynamics of a flexible portal frame under support excitation

De Paula, Aline Souza; Balthazar, José Manoel; Felix, Jorge Luis Palacios
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 957-963
ENG
Relevância na Pesquisa
66.43%
This paper presents a nonlinear dynamic analysis of a flexible portal frame subjected to support excitation, which is provided by an electro-dynamical shaker. The problem is reduced to a mathematical model of four degrees of freedom and the equations of motion are derived via Lagrangian formulation. The main goal of this study is to investigate the dynamic interactions between a flexible portal frame and a non-ideal support excitation. The numerical analysis shows a complex behavior of the system, which can be observed by phase spaces, Poincaŕ sections and bifurcation diagrams. © 2012 American Institute of Physics.

On elimination of chaotic behavior in a non-ideal portal frame structural system, using both passive and active controls

Tusset, Angelo Marcelo; Balthazar, José Manoel; Felix, Jorge Luis Palacios
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 803-813
ENG
Relevância na Pesquisa
46.16%
In this paper, an application is considered of both active and passive controls, to suppression of chaotic behavior of a simple portal frame, under the excitation of an unbalanced DC motor, with limited power supply (non-ideal problem). The adopted active control strategy consists of two controls: the nonlinear (feedforward) in order to keep the controlled system in a desirable orbit, and the feedback control, which may be obtained by considering state-dependent Riccati equation control to bringing the system into the desired orbit using a magneto rheological (MR) damper. To control the electric current applied in control of the MR damper the Bouc-Wen mathematical model was used to the MR damper. The passive control was obtained by means of a nonlinear sub-structure with properties of nonlinear energy sink. Simulations showed the efficiency of both the passive control (energy pumping) and active control strategies in the suppression of the chaotic behavior. © The Author(s) 2012.

A non-ideal portal frame energy harvester controlled using a pendulum

Iliuk, I.; Balthazar, José Manoel; Tusset, A. M.; Piqueira, J. R C; Rodrigues de Pontes, B.; Felix, J. L P; Bueno, Á
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1575-1586
ENG
Relevância na Pesquisa
46.33%
A model of energy harvester based on a simple portal frame structure is presented. The system is considered to be non-ideal system (NIS) due to interaction with the energy source, a DC motor with limited power supply and the system structure. The nonlinearities present in the piezoelectric material are considered in the piezoelectric coupling mathematical model. The system is a bi-stable Duffing oscillator presenting a chaotic behavior. Analyzing the average power variation, and bifurcation diagrams, the value of the control variable that optimizes power or average value that stabilizes the chaotic system in the periodic orbit is determined. The control sensitivity is determined to parametric errors in the damping and stiffness parameters of the portal frame. The proposed passive control technique uses a simple pendulum to tuned to the vibration of the structure to improve the energy harvesting. The results show that with the implementation of the control strategy it is possible to eliminate the need for active or semi active control, usually more complex. The control also provides a way to regulate the energy captured to a desired operating frequency. © 2013 EDP Sciences and Springer.

Some comments on the nonlinear dynamics of a portal frame under base excitation

Paula, Aline Souza de; Balthazar, Jose Manoel; Palacios Felix, Jorge Luis
Fonte: IOS Press Publicador: IOS Press
Tipo: Artigo de Revista Científica Formato: 1093-1101
ENG
Relevância na Pesquisa
66.43%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); This paper presents a nonlinear dynamic analysis of a flexible portal frame subjected to support excitation, which is provided by an electro-dynamical shaker. The main goal of this study is to investigate the dynamic interactions between a flexible portal frame and a nonlinear electrical support excitation. The numerical analysis shows a complex behavior of the system, which can be observed by phase spaces, Poincare sections and bifurcation diagrams.

Application of passive control to energy harvester efficiency using a nonideal portal frame structural support system

Iliuk, Itamar; Balthazar, Jose M.; Tusset, Angelo M.; Piqueira, Jose R. C.; Pontes, Bento R. de; Felix, Jorge L. P.; Bueno, Atila M.
Fonte: Sage Publications Ltd Publicador: Sage Publications Ltd
Tipo: Artigo de Revista Científica Formato: 417-429
ENG
Relevância na Pesquisa
46.33%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); An analysis of a new energy harvester model is presented, based on a simple portal frame structure, considered a nonideal system due to the kind of excitation influenced by the response of the system, such as a direct current motor with limited power supply. The horizontal motion of the portal frame is considered under a nonideal excitation, and the approximated mathematical model of the system is obtained, considering the coupled oscillators. To model the piezoelectric coupling, the nonlinearities of the piezoelectric material were considered. A constantly sustained energy harvesting is essential for using these devices in real applications; for this, a control strategy is required. Passive control was obtained by means of a nonlinear substructure with properties of nonlinear energy sink. Numerical simulations were performed in order to find best values of control parameters. To check the robustness of the control strategy, an analysis considering uncertainties in the parameters of the model was performed, showing the efficiency of the passive control (energy pumping) in the suppression of the chaotic behavior...

Potential Application in Energy Harvesting of Intermodal Energy Exchange in a Frame: FEM Analysis

Iliuk, Itamar; Rebello da Fonseca Brasil, Reyolando Manoel Lopes; Balthazar, Jose Manoel; Tusset, Angelo Marcelo; Piccirillo, Vinicius; Castilho Piqueira, Jose Roberto
Fonte: World Scientific Publ Co Pte Ltd Publicador: World Scientific Publ Co Pte Ltd
Tipo: Artigo de Revista Científica Formato: 10
ENG
Relevância na Pesquisa
35.99%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); This paper presents a Finite Element Analysis (FEA) of modal energy exchange and harvesting in a simple portal frame structure. We consider both horizontal and vertical support excitations resonant first with the first mode (sway mode) and latter with the second mode (the first symmetrical mode). As 2:1 internal resonance is present between these two modes, the phenomena of mode saturation and energy exchange (modal coupling) may occur. Thus, energy pumped into the system through one of the modes, is partially transferred to the other mode, not directly excited. An evaluation of the energy available for harvesting in each of the considered mode is computed.

Multiple scales analysis of nonlinear oscillations of a portal frame foundation for several machines

Brasil,Reyolando M. L. R. F.
Fonte: The Brazilian Society of Mechanical Sciences Publicador: The Brazilian Society of Mechanical Sciences
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/1999 EN
Relevância na Pesquisa
46.28%
An analytical study of the nonlinear vibrations of a multiple machines portal frame foundation is presented. Two unbalanced rotating machines are considered, none of them resonant with the lower natural frequencies of the supporting structure. Their combined frequencies is set in such a way as to excite, due to nonlinear behavior of the frame, either the first anti-symmetrical mode (sway) or the first symmetrical mode. The physical and geometrical characteristics of the frame are chosen to tune the natural frequencies of these two modes into a 1:2 internal resonance. The problem is reduced to a two degrees of freedom model and its nonlinear equations of motions are derived via a Lagrangian approach. Asymptotic perturbation solutions of these equations are obtained via the Multiple Scales Method.

On non-ideal and non-linear portal frame dynamics analysis using bogoliubov averaging method

Palacios,J. L.; Balthazar,J. M.; Brasil,R. M. L. R. F.
Fonte: The Brazilian Society of Mechanical Sciences Publicador: The Brazilian Society of Mechanical Sciences
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2002 EN
Relevância na Pesquisa
36.16%
We apply the Bogoliubov Averaging Method to the study of the vibrations of an elastic foundation, forced by a Non-ideal energy source. The considered model consists of a portal plane frame with quadratic nonlinearities, with internal resonance 1:2, supporting a direct current motor with limited power. The non-ideal excitation is in primary resonance in the order of one-half with the second mode frequency. The results of the averaging method, plotted in time evolution curve and phase diagrams are compared to those obtained by numerically integrating of the original differential equations. The presence of the saturation phenomenon is verified by analytical procedures.

Developing a Trade Information Portal

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
Relevância na Pesquisa
36.2%
A number of countries have introduced or are considering the introduction of a trade information portal as a means of facilitating trade and increasing transparency. For World Trade Organization (WTO) members or countries in the process of acceding to the WTO, a trade information portal will assist in complying with new commitments currently being negotiated as part of the Doha Development Round. The negotiations aim to strengthen the provisions of Article X of General Agreement on Tariffs and Trade (GATT) which currently requires that all regulatory trade related information "shall be published promptly in such a manner as to enable governments and traders to become acquainted with them". In many developing nations, government agency specific websites may not exist and even when they do they are often incomplete, out of date, or the content may not cover the entire spectrum of information that a trader may wish to obtain to ensure compliance with import, export, or transit requirements. It is therefore desirable to create a single platform where all the information relating to trade from all the various agencies is aggregated under one roof and is readily available for searching and viewing. This guide discusses the issues and challenges that developing nations are likely to face when implementing a trade information portal and provides a checklist of practical guidelines for the steps that might be required in order to achieve effective implementation.

An??lisis din??mico de p??rgolas para el ferrocarril de alta velocidad

Maldonado Salguero, Patricia
Fonte: Universidade de Granada Publicador: Universidade de Granada
Tipo: Trabalho de Conclusão de Curso
SPA
Relevância na Pesquisa
46.33%
El dise??o exigente de las l??neas de ferrocarril y en especial de las l??neas alta velocidad, presenta en ocasiones la problem??tica de resolver cruces a distinto nivel mediante trazados fuertemente esviados. Aparece la necesidad de dise??ar estructuras cuya longitud m??nima viene condicionada por el ancho del vial inferior y el ??ngulo de cruce entre las dos l??neas, dando lugar a luces elevadas donde la p??rgola se convierte en la mejor soluci??n. La finalidad de este proyecto es analizar las posibilidades de modelizaci??n de p??rgolas y su respuesta din??mica atendiendo al reducido n??mero de publicaciones existentes actualmente sobre el tema. Se pretenden buscar modelos simplificados basados en losas ort??tropas cuyo comportamiento sea v??lidado tanto en an??lisis est??tico como din??mico, el estudio de la incidencia del esviaje en las respuestas din??micas debidas al paso de los trenes y el c??lculo din??mico de p??rgolas reales. La normativa vigente espa??ola impone la realizaci??n del c??lculo din??mico mediante in- tegraci??n directa en el tiempo con cargas m??viles en aquellas estructuras que precisen comprobaciones en cualquier rango de velocidades, para puentes isost??ticos e hiperest??ticos, sin limitar la masa ni las frecuencias. Este es el m??todo necesario a aplicar en p??rgolas para los an??lisis realizados en el presente proyecto. La soluci??n al problema de paso de cargas m??- viles se ha resuelto tradicionalmente mediante el m??todo de elementos finitos...

La aportación estructural del Crystal Palace de la Exposición Universal de Londres 1851. Una ampliación del enfoque histórico tradicional.

López César, Isaac
Fonte: Redfundamentos Publicador: Redfundamentos
Tipo: Artigo de Revista Científica
SPA
Relevância na Pesquisa
46.33%
[Resumen] El objetivo del presente artículo es el de establecer la línea histórica que conduce desde la aplicación arquitectónica de los primeros elementos estructurales de hierro industrializado en edificios de varias plantas y cubiertas hasta la aplicación primigenia del pórtico rígido autoportante en un edificio de varias plantas. En este recorrido, el Crystal Palace de la Exposición Universal de Londres 1851 se revela como un elemento clave que articula la transición desde la tipología de entramado metálico estabilizado por muros perimetrales de fábrica hasta la moderna formalización del pórtico rígido autoestable aplicado al edificio en altura. Asimismo, se detectan las conexiones históricas existentes en dicho proceso, poniendo en valor edificios que han permanecido al margen de la historiografía arquitectónica convencional. Ampliamos, por tanto, el foco histórico centrado tradicionalmente en los logros de la Escuela de Chicago destacando y conectando históricamente los acontecimientos anteriores.; [Abstract] The aim of this paper is to establish a historical line from the first architectural application of structural elements made of industrial iron for roofs and multi-storey buildings to the first application of portal frame in a multi-storey building. With this in mind...

Accounting for moment-rotation behaviour of connections in portal frames

Albertyn,H L; Haas,T N; Dunaiski,P E
Fonte: Journal of the South African Institution of Civil Engineering Publicador: Journal of the South African Institution of Civil Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
36.49%
Portal frames are steel structures used to construct industrial buildings. Conventional analysis techniques used by practising engineering professionals assume that the eave, ridge and base connections are either infinitely rigid or perfectly pinned. This approach leads to less accurate analysis of the displacement behaviour of portal frames when subjected to external loading. Portal frames must therefore be analysed with rotational springs at all connections to yield accurate displacement behaviour. This investigation focused on determining the accuracy and economic feasibility of modelling portal frame connections with rotational springs. The rotational spring stiffnesses of all connections were required before the portal frame could be analysed in a second-order two-dimensional non-linear analysis. The rotational spring stiffnesses unique to each connection were determined from the moment-rotation behaviour obtained from a series of finite element analysis simulations of each connection. Thereafter these stiffnesses were used to determine the vertical and horizontal displacements of the portal frame. These displacements were compared with experimental test results. The reasons for the discrepancies between the numerical and experimental results were investigated through a sensitivity analysis. The findings suggest that it is not computationally feasible to analyse portal frames with rotational springs...