Terremotos são movimentos bruscos e de curta duração da superfície terrestrecaracterizados pela l... more Terremotos são movimentos bruscos e de curta duração da superfície terrestrecaracterizados pela liberação de grande energia. A natureza dos fenômenos relacionados aossismos é complexa e ainda pouco compreendida. Entretanto, muitos aspectos de interesse domecanismo de origem da excitação sísmica podem ser explicados a partir de um movimentoinstável, denominado movimento de aderência-deslizamento. Este tipo de movimento éatualmente considerado como o mais provável mecanismo de origem dos sismos superficiais.Neste trabalho, emprega-se o Método dos Elementos Discretos na modelagem numéricabidimensional do movimento de aderência-deslizamento de um bloco prismático apoiado sobreuma superfície rígida. A superfície de falha é modelada pela lei de atrito de Coulomb.Partindo-se de estudo prévio conduzido por Doz, procura-se um aperfeiçoamento do modelopela consideração da heterogeneidade do meio. Propriedades aleatórias são consideradas pararepresentar a heterogeneidade do material. Os result...
For the range of medium spans, around 30 to 40m, composite footbridges are getting popular in Bra... more For the range of medium spans, around 30 to 40m, composite footbridges are getting popular in Brazil. This kind of structure consists on longitudinal steel truss beams providing support for a concrete deck usually made of precast elements. Typical examples of these structures may be found in many cities in Brazil, especially in Brasilia where a large number of highways demanded a significant set of footbridges. Due to the amount of this kind of composite footbridges in Brazil, studies concerning their mechanical behavior are required in order to ensure pedestrian’s safety. For this end, in this paper, a typical Brazilian composite footbridge located in Brasilia is analyzed by means of experimental tests and computational modeling. The focus is the determination of natural frequencies and mode shapes. Strategies to correctly obtain the vertical modes are also discussed since vertical vibration is the main vibration problem expected for the tested footbridge. The obtained results show...
Buildings are composed of several systems, each with specific designs and regulations to ensure t... more Buildings are composed of several systems, each with specific designs and regulations to ensure that constructions are safe and viable. Many residential, commercial, and industrial buildings have systems with gas central storage, which must be subjected to strict safety criteria to avoid accidents. In addition to the safety mechanisms provided by manufacturers, designers of these gas central storage must consider other devices to reduce explosion risk and mitigate the damaging blast effects. Explosions are physical-chemical phenomena that are characterized by the sudden expansion of a material and, consequently, energy release. When an accidental explosion occurs, much damage is caused by the shock wave and fragments. In the case of pressure vessels, a mechanical explosion can occur. Studying this explosion is essential to developing a more reliable, safe design for surrounding buildings and its users. This work aims to study the effects of gas tank explosions. In this study, the Autodyn computational tool based on fluid dynamics (CFD) is used. This software allows the modeling of complex explosion scenarios and the evaluation of blast wave parameters. For each numerical model, the overpressure levels outdoors and indoors are evaluated. The results indicated how the wave overpressures are distributed in different scenarios, and from them, it was possible to analyze the damaging levels.
Revista Sul-Americana de Engenharia Estrutural, Oct 19, 2017
Pesquisas relacionadas às explosões e à propagação das ondas de choque são de grande importância ... more Pesquisas relacionadas às explosões e à propagação das ondas de choque são de grande importância dada sua grande aplicabilidade em diversos setores produtivos, como, por exemplo, na indústria, na mineração e na engenharia. Quando não planejadas, a detonação de explosivos químicos, como o TNT, pode representar um risco severo às instalações e seus usuários. As
Proceedings of the 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2015
In recent years a vibration control technique, called structural coupling, has been studied. This... more In recent years a vibration control technique, called structural coupling, has been studied. This technique consists on linking two neighboring buildings, through a coupling device, with the purpose of reducing dynamic response. It is possible to control both structures response simultaneously, which is precisely the attractiveness of the technique. Several researchers explored the effectiveness of various seismic control devices, in connecting two adjacent buildings, considering they are supported on a fixed base. However, in general, all structures interacts with the surrounding soil, what substantially affects the dynamic response, it is called soil-structure interaction (SSI). Considering SSI on structural coupling is still incipient in literature. This work aims to evaluate SSI influence on the performance of this control technique, besides of presenting a simple analysis methodology to this type of problem. The results found show that SSI effects cannot be neglected on dynamic analysis of coupled structures. It was verified that changes on system natural frequencies due to SSI are important since, depending on earthquake frequency components, it modifies also the dynamic response of the system. All analysis were performed using MATLAB software.
Fabrication technology and structural engineering states-of-art have led to a growing use of slen... more Fabrication technology and structural engineering states-of-art have led to a growing use of slender structures, making them more susceptible to static and dynamic actions that may lead to some sort of damage. In this context, regular inspections and evaluations are necessary to detect and predict structural damage and establish maintenance actions able to guarantee structural safety and durability with minimal cost. However, these procedures are traditionally quite time-consuming and costly, and techniques allowing a more effective damage detection are necessary. This paper assesses the potential of Artificial Neural Network (ANN) models in the prediction of damage localization in structural members, as function of their dynamic propertiesthe three first natural frequencies are used. Based on 64 numerical examples from damaged (mostly) and undamaged steel channel beams, an ANN-based analytical model is proposed as a highly accurate and efficient damage localization estimator. The proposed model yielded maximum errors of 0.2 and 0.7 % concerning 64 numerical and 3 experimental data points, respectively. Due to the high-quality of results, authors' next step is the application of similar approaches to entire structures, based on much larger datasets.
Resumo. Este artigo descreve o emprego das tecnicas de atualizacao e identificacao de danos imple... more Resumo. Este artigo descreve o emprego das tecnicas de atualizacao e identificacao de danos implementados em pacotes de softwares comerciais, visando o monitoramento do comportamento global de vigas intactas e danificadas. Como referencia do processo de atualizacao dos modelos numericos, foi utilizada a analise experimental de vigas de aco sob condicoes de apoio livre-livre, das quais foram obtidos os registros de aceleracoes e estimadas suas propriedades dinâmicas. A fim de identificar danos no modelo experimental, utilizou-se a tecnica de Redes Neurais Artificiais (RNAs), especificamente, Self Organizing Maps (SOM) e metodos de atualizacao do modelo numerico. Finalmente, pretende-se neste artigo avaliar a capacidade de prever a integridade estrutural por meio dos metodos de atualizacao e identificacao de danos utilizando os dados das respostas dinâmicas. Palavras Chave: Elementos Finitos, Dinâmica Estrutural, Otimizacao, Identificacao de Dano, Redes Neurais Artificiais
As torres metalicas autoportantes sao estruturas de aco utilizadas principalmente na area de tele... more As torres metalicas autoportantes sao estruturas de aco utilizadas principalmente na area de telecomunicacao para sustentacao das antenas. A exigencia tecnica para que estas torres possam ser utilizadas como estrutura de sustentacao esta na limitacao dos seus movimentos, pois o correto direcionamento das antenas e essencial para uma satisfatoria propagacao dos sinais magneticos. O conhecimento das acoes do vento, considerado como a principal fonte de excitacao das torres, e o conhecimento do comportamento dessas estruturas em face dos carregamentos a elas aplicados podem auxiliar na previsao do real movimento da torre. Este trabalho tem como objetivo analisar o comportamento das torres metalicas autoportantes na direcao do vento considerando o aspecto dinâmico do mesmo. Para tal analise tres metodos foram estudados e aplicados a tres torres autoportantes quadradas, com alturas de 50, 70 e 90 m: o metodo de Davenport, o metodo de simulacao de Monte Carlo e o metodo discreto da NBR-61...
Revista Internacional de Desastres Naturales, Accidentes e Infraestructura Civil, Dec 7, 2018
Resumen: En la gran mayoría de normas o códigos de diseño y construcción de estructuras sismo res... more Resumen: En la gran mayoría de normas o códigos de diseño y construcción de estructuras sismo resistentes, las mudanzas en la geometría de las estructuras son llamadas de irregularidades y se dividen en dos tipos: irregularidades en planta e irregularidades en altura, siendo las últimas ampliamente investigadas. En ese sentido, el objetivo del presente trabajo es estudiar en detalle la influencia de las irregularidades en planta en la resistencia sísmica de una estructura de ocho pisos y con pórticos de concreto armado, con el fin de cuantificar y localizar zonas vulnerables en la estructura en las que posiblemente se necesite hacer un control de daños. El estudio propuesto se desarrolla numéricamente utilizando los softwares ETABS Nonlinear v9.7.2 y MATLAB R2009b. Los resultados demostraron que las irregularidades en planta a medida que se colocan en la estructura, ésta va perdiendo su capacidad portante y por ende su capacidad de resistir las cargas de servicio.
In recent years a vibration control technique, called structural coupling, has been studied. This... more In recent years a vibration control technique, called structural coupling, has been studied. This technique consists on linking two neighboring buildings, through a coupling device, with the purpose of reducing dynamic response. It is possible to control both structures response simultaneously, which is precisely the attractiveness of this technique. Given the potential of the structural coupling technique, this work evaluates numerically and experimentally the performance of the structural coupling technique in simple plane frames when subjected to an oscillatory movement in at base caused by a shaking table, designed and built in the Structure Laboratory of University of Brasilia. Initially, the model numerical dynamic responses, without and with coupling, were obtained. Then, experimentally, the plane frames were fixed to the shaking table and subjected to a base movement uncoupled and coupled in order to obtain the acceleration registers and its frequency spectra. Finally, numerical and experimental frequency spectra were compared. The results obtained showed the efficiency of the control method through coupling, which depends mainly on the mechanical properties of adjacent buildings and connecting devices.
Conference proceedings of the Society for Experimental Mechanics, Jun 12, 2018
In view of the need to satisfactorily provide good performance of structures in their service sit... more In view of the need to satisfactorily provide good performance of structures in their service situations, it is desired to understand the influence of some reinforced concrete particularities on the dynamic parameters of the structure. These particularities are fundamental in static analysis of pavements design. Starting from spans, geometry, and structural typologies common in real buildings, this paper studies the influence of cracking and non-constant reinforcements on the vibration frequency of concrete floors. It is shown that the reinforced concrete properties significantly impact the floor’s dynamic parameters; this impact is stronger when the floor is slender and deformable. Some of the common structural typologies, as the ribbed/waffle slabs, are even more susceptible to those influence. Knowing the main variables that may be responsible for excessive vibration phenomenon, it was possible to prevent issues during the design process.
Terremotos são movimentos bruscos e de curta duração da superfície terrestrecaracterizados pela l... more Terremotos são movimentos bruscos e de curta duração da superfície terrestrecaracterizados pela liberação de grande energia. A natureza dos fenômenos relacionados aossismos é complexa e ainda pouco compreendida. Entretanto, muitos aspectos de interesse domecanismo de origem da excitação sísmica podem ser explicados a partir de um movimentoinstável, denominado movimento de aderência-deslizamento. Este tipo de movimento éatualmente considerado como o mais provável mecanismo de origem dos sismos superficiais.Neste trabalho, emprega-se o Método dos Elementos Discretos na modelagem numéricabidimensional do movimento de aderência-deslizamento de um bloco prismático apoiado sobreuma superfície rígida. A superfície de falha é modelada pela lei de atrito de Coulomb.Partindo-se de estudo prévio conduzido por Doz, procura-se um aperfeiçoamento do modelopela consideração da heterogeneidade do meio. Propriedades aleatórias são consideradas pararepresentar a heterogeneidade do material. Os result...
For the range of medium spans, around 30 to 40m, composite footbridges are getting popular in Bra... more For the range of medium spans, around 30 to 40m, composite footbridges are getting popular in Brazil. This kind of structure consists on longitudinal steel truss beams providing support for a concrete deck usually made of precast elements. Typical examples of these structures may be found in many cities in Brazil, especially in Brasilia where a large number of highways demanded a significant set of footbridges. Due to the amount of this kind of composite footbridges in Brazil, studies concerning their mechanical behavior are required in order to ensure pedestrian’s safety. For this end, in this paper, a typical Brazilian composite footbridge located in Brasilia is analyzed by means of experimental tests and computational modeling. The focus is the determination of natural frequencies and mode shapes. Strategies to correctly obtain the vertical modes are also discussed since vertical vibration is the main vibration problem expected for the tested footbridge. The obtained results show...
Buildings are composed of several systems, each with specific designs and regulations to ensure t... more Buildings are composed of several systems, each with specific designs and regulations to ensure that constructions are safe and viable. Many residential, commercial, and industrial buildings have systems with gas central storage, which must be subjected to strict safety criteria to avoid accidents. In addition to the safety mechanisms provided by manufacturers, designers of these gas central storage must consider other devices to reduce explosion risk and mitigate the damaging blast effects. Explosions are physical-chemical phenomena that are characterized by the sudden expansion of a material and, consequently, energy release. When an accidental explosion occurs, much damage is caused by the shock wave and fragments. In the case of pressure vessels, a mechanical explosion can occur. Studying this explosion is essential to developing a more reliable, safe design for surrounding buildings and its users. This work aims to study the effects of gas tank explosions. In this study, the Autodyn computational tool based on fluid dynamics (CFD) is used. This software allows the modeling of complex explosion scenarios and the evaluation of blast wave parameters. For each numerical model, the overpressure levels outdoors and indoors are evaluated. The results indicated how the wave overpressures are distributed in different scenarios, and from them, it was possible to analyze the damaging levels.
Revista Sul-Americana de Engenharia Estrutural, Oct 19, 2017
Pesquisas relacionadas às explosões e à propagação das ondas de choque são de grande importância ... more Pesquisas relacionadas às explosões e à propagação das ondas de choque são de grande importância dada sua grande aplicabilidade em diversos setores produtivos, como, por exemplo, na indústria, na mineração e na engenharia. Quando não planejadas, a detonação de explosivos químicos, como o TNT, pode representar um risco severo às instalações e seus usuários. As
Proceedings of the 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2015
In recent years a vibration control technique, called structural coupling, has been studied. This... more In recent years a vibration control technique, called structural coupling, has been studied. This technique consists on linking two neighboring buildings, through a coupling device, with the purpose of reducing dynamic response. It is possible to control both structures response simultaneously, which is precisely the attractiveness of the technique. Several researchers explored the effectiveness of various seismic control devices, in connecting two adjacent buildings, considering they are supported on a fixed base. However, in general, all structures interacts with the surrounding soil, what substantially affects the dynamic response, it is called soil-structure interaction (SSI). Considering SSI on structural coupling is still incipient in literature. This work aims to evaluate SSI influence on the performance of this control technique, besides of presenting a simple analysis methodology to this type of problem. The results found show that SSI effects cannot be neglected on dynamic analysis of coupled structures. It was verified that changes on system natural frequencies due to SSI are important since, depending on earthquake frequency components, it modifies also the dynamic response of the system. All analysis were performed using MATLAB software.
Fabrication technology and structural engineering states-of-art have led to a growing use of slen... more Fabrication technology and structural engineering states-of-art have led to a growing use of slender structures, making them more susceptible to static and dynamic actions that may lead to some sort of damage. In this context, regular inspections and evaluations are necessary to detect and predict structural damage and establish maintenance actions able to guarantee structural safety and durability with minimal cost. However, these procedures are traditionally quite time-consuming and costly, and techniques allowing a more effective damage detection are necessary. This paper assesses the potential of Artificial Neural Network (ANN) models in the prediction of damage localization in structural members, as function of their dynamic propertiesthe three first natural frequencies are used. Based on 64 numerical examples from damaged (mostly) and undamaged steel channel beams, an ANN-based analytical model is proposed as a highly accurate and efficient damage localization estimator. The proposed model yielded maximum errors of 0.2 and 0.7 % concerning 64 numerical and 3 experimental data points, respectively. Due to the high-quality of results, authors' next step is the application of similar approaches to entire structures, based on much larger datasets.
Resumo. Este artigo descreve o emprego das tecnicas de atualizacao e identificacao de danos imple... more Resumo. Este artigo descreve o emprego das tecnicas de atualizacao e identificacao de danos implementados em pacotes de softwares comerciais, visando o monitoramento do comportamento global de vigas intactas e danificadas. Como referencia do processo de atualizacao dos modelos numericos, foi utilizada a analise experimental de vigas de aco sob condicoes de apoio livre-livre, das quais foram obtidos os registros de aceleracoes e estimadas suas propriedades dinâmicas. A fim de identificar danos no modelo experimental, utilizou-se a tecnica de Redes Neurais Artificiais (RNAs), especificamente, Self Organizing Maps (SOM) e metodos de atualizacao do modelo numerico. Finalmente, pretende-se neste artigo avaliar a capacidade de prever a integridade estrutural por meio dos metodos de atualizacao e identificacao de danos utilizando os dados das respostas dinâmicas. Palavras Chave: Elementos Finitos, Dinâmica Estrutural, Otimizacao, Identificacao de Dano, Redes Neurais Artificiais
As torres metalicas autoportantes sao estruturas de aco utilizadas principalmente na area de tele... more As torres metalicas autoportantes sao estruturas de aco utilizadas principalmente na area de telecomunicacao para sustentacao das antenas. A exigencia tecnica para que estas torres possam ser utilizadas como estrutura de sustentacao esta na limitacao dos seus movimentos, pois o correto direcionamento das antenas e essencial para uma satisfatoria propagacao dos sinais magneticos. O conhecimento das acoes do vento, considerado como a principal fonte de excitacao das torres, e o conhecimento do comportamento dessas estruturas em face dos carregamentos a elas aplicados podem auxiliar na previsao do real movimento da torre. Este trabalho tem como objetivo analisar o comportamento das torres metalicas autoportantes na direcao do vento considerando o aspecto dinâmico do mesmo. Para tal analise tres metodos foram estudados e aplicados a tres torres autoportantes quadradas, com alturas de 50, 70 e 90 m: o metodo de Davenport, o metodo de simulacao de Monte Carlo e o metodo discreto da NBR-61...
Revista Internacional de Desastres Naturales, Accidentes e Infraestructura Civil, Dec 7, 2018
Resumen: En la gran mayoría de normas o códigos de diseño y construcción de estructuras sismo res... more Resumen: En la gran mayoría de normas o códigos de diseño y construcción de estructuras sismo resistentes, las mudanzas en la geometría de las estructuras son llamadas de irregularidades y se dividen en dos tipos: irregularidades en planta e irregularidades en altura, siendo las últimas ampliamente investigadas. En ese sentido, el objetivo del presente trabajo es estudiar en detalle la influencia de las irregularidades en planta en la resistencia sísmica de una estructura de ocho pisos y con pórticos de concreto armado, con el fin de cuantificar y localizar zonas vulnerables en la estructura en las que posiblemente se necesite hacer un control de daños. El estudio propuesto se desarrolla numéricamente utilizando los softwares ETABS Nonlinear v9.7.2 y MATLAB R2009b. Los resultados demostraron que las irregularidades en planta a medida que se colocan en la estructura, ésta va perdiendo su capacidad portante y por ende su capacidad de resistir las cargas de servicio.
In recent years a vibration control technique, called structural coupling, has been studied. This... more In recent years a vibration control technique, called structural coupling, has been studied. This technique consists on linking two neighboring buildings, through a coupling device, with the purpose of reducing dynamic response. It is possible to control both structures response simultaneously, which is precisely the attractiveness of this technique. Given the potential of the structural coupling technique, this work evaluates numerically and experimentally the performance of the structural coupling technique in simple plane frames when subjected to an oscillatory movement in at base caused by a shaking table, designed and built in the Structure Laboratory of University of Brasilia. Initially, the model numerical dynamic responses, without and with coupling, were obtained. Then, experimentally, the plane frames were fixed to the shaking table and subjected to a base movement uncoupled and coupled in order to obtain the acceleration registers and its frequency spectra. Finally, numerical and experimental frequency spectra were compared. The results obtained showed the efficiency of the control method through coupling, which depends mainly on the mechanical properties of adjacent buildings and connecting devices.
Conference proceedings of the Society for Experimental Mechanics, Jun 12, 2018
In view of the need to satisfactorily provide good performance of structures in their service sit... more In view of the need to satisfactorily provide good performance of structures in their service situations, it is desired to understand the influence of some reinforced concrete particularities on the dynamic parameters of the structure. These particularities are fundamental in static analysis of pavements design. Starting from spans, geometry, and structural typologies common in real buildings, this paper studies the influence of cracking and non-constant reinforcements on the vibration frequency of concrete floors. It is shown that the reinforced concrete properties significantly impact the floor’s dynamic parameters; this impact is stronger when the floor is slender and deformable. Some of the common structural typologies, as the ribbed/waffle slabs, are even more susceptible to those influence. Knowing the main variables that may be responsible for excessive vibration phenomenon, it was possible to prevent issues during the design process.
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