Análise da Estrutura de um Edifício em Betão Armado Usando um Método dos Elementos Finitos

Pretende-se, utilizando o Modelo da Elasticidade Linear em freeFEM++, determinar os esforços e deslocamentos de um edifício alto submetido apenas à acção do peso próprio da estrutura e, efectuar estudos comparativos dos resultados obtidos com o SAP2000. O trabalho inicia-se com a introdução da teoria da elasticidade linear, onde são feitas as deduções das Equações de Compatibilidade, Equilíbrio e as Leis Constitutivas, de modo a resolver numericamente o problema de Elasticidade Linear mencionado. O método de elementos finitos será implementado em freeFEM++ com auxílio do GMSH que é uma poderosa ferramenta com capacidade de gerar automaticamente malhas tridimensionais de elementos finitos e com relativa facilidade de pré e pós-processamento.

Comportamento Sísmico dos Edifícios Caracterização Sísmica dos Edifícios

A deficiência de muitas construções no que diz respeito à sua resistência sísmica no mundo despertou-se o interesse do autor em abordar os problemas de dimensionamento sísmico, concepção e da construção em Cabo Verde. A gravidade do risco sísmico hoje em dia obriga de uma certa forma aos projectistas a melhorar as técnicas de dimensionamento sísmico e da sua concepção. Cabo verde historicamente não tem nenhum registo de casos de sismo alarmante mas possui registo de sismo embora de fraca magnitude. Em cabo verde os edifícios na sua maioria não são dimensionados pela acção sísmica, o que levou ao autor fazer neste trabalho, uma análise sísmica dos edifícios em betão armado, onde teve que simular um edifício construída numa zona sísmica na ilha da Brava, por ser a ilha mais sísmica em Cabo Verde. O método de cálculo utilizado foi o de Rayleigh, com ajuda dum programa Sap2000, baseado no regulamento de Cabo Verde (RASE), que entrará brevemente em vigor.

Ação do vento em cobertura de madeira roliça para galpões de fertilizantes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Segurança estrutural de uma ponte ferroviária em concreto armado sobre o rio Mãe Maria

O estudo do comportamento de pontes ferroviárias vem tomando grande destaque na área experimental, devido muitas das vezes haver a necessidade de um aumento dessas cargas móveis. A companhia VALE a partir de um convênio estabelecido com a UFPA (Universidade Federal do Pará), buscou realizar estudos das capacidades resistentes das pontes ferroviárias, que compõem a Estrada de Ferro Carajás (EFC), para futuros casos de carregamentos que passarão de 32 tf para 40 tf, o que provoca mudanças consideráveis no comportamento da estrutura. A falta de manutenção ou uma manutenção irregular das pontes de concreto armado podem resultar em manifestações patológicas que podem comprometer a segurança e ao risco de intervenção do escoamento. Dentre as OAE’s (Obras de Arte Especial) já analisadas, encontra-se a ponte sobre o Rio Mãe Maria localizada no município de Marabá, estado do Pará, transpondo o rio Mãe Maria, identificada como OAE 50A, apresenta um traçado retilíneo executada em concreto armado moldada “in loco”, é constituída por dois vãos hiperestáticos, totalizando 64,20 m, transpondo o leito do rio em dois vãos de 20 m e com seção transversal oferecendo a largura de 5,85 m. Com isso tornou-se indispensável para avaliação de sua integridade física a monitoração com extensômetros elétricos de resistência (EER) dos elementos (laje, longarina, blocos, encontros e tubulões) que compões a estrutura durante a passagem dos trens carregados de minério. Além da monitoração, foram realizados ensaios não-destrutivos como: dureza superficial através da esclerometria e a estimativa do cobrimento da armadura e localização da mesma por meio da pacometria, ensaios destrutivos como: extração de corpos-de-prova para determinar a compressão diametral e o módulo de elasticidade do concreto e a resistência a penetração através do teste de carbonatação inerentes a questão de durabilidade do mesmo, que serão comparados com a memória de cálculo e com os modelos computacionais tridimensionais desenvolvidos via “software” comercialSAP2000® (COMPUTERS AND STRUCTURES), que utiliza o método dos elementos finitos (MEF). O MEF foi utilizado para obtenção dos esforços permitindo as verificações de segurança de acordo com as recomendações normativas, tais análises comparativas são apresentadas e discutidas para a conclusão do comportamento das longarinas. Conhecendo com precisão a capacidade estrutural da ponte e a sua vida útil, pode-se assegurar o tráfego de composições com maior segurança.

Considerações e avaliações das solicitações em estruturas de edificações de paredes de concreto pré-moldado utilizando o modelo de pórtico tridimensional: estudo de caso

The present study is in reference to precast concrete (panels) walls as the main structural system. The diversification of the structural systems is a reality due to specific characteristics', as a result there is a lack of study and analysis. Some systems are already established in their applications, for instance: conventional reinforced concrete, structural masonry, metal structures, and wood structure. Apart from this precast concrete elements has had a growth in building sites in Brazil, therefore professionals should be more aware. Affordable house funding initiatives to address the housing shortage has been recurrent throughout the country, additionally precast concrete walls has been an alternative that meets the three basic concepts of engineering, which are: the technique, economy, and security. The objective of this study is to gather concepts from the literature and TOMO (2012) about precast concrete walls and make a didactic synthesis of how they are viewed. The modeling structure method of the system was performed following the concept of assigning bars, using the computer program of calculations SAP2000. Initially will be presented a theoretical part, furthermore a case study to illustrate the sizing of the walls using EXCEL tables programmed with calculation routine. The results will be presented in calculated efforts by the program for further analysis. Finally, will be highlighted important items of modeling and interpretation of the results

Considerações sobre a análise de segunda ordem de estais utilizados em torres metálicas e flares

This work is consideration of an analysis of second-order (nonlinear analysis) applied to e metal towers and flares. The analysis is mainly done using the wind efforts and the weight of the structure. The analysis itself is carried out with the aid of a structural analysis software, SAP2000 where two proposes modeling. The first for the linear effects and the second for the nonlinear effects

Considerações sobre a análise de segunda ordem de estais utilizados em torres metálicas e flares

This work is consideration of an analysis of second-order (nonlinear analysis) applied to e metal towers and flares. The analysis is mainly done using the wind efforts and the weight of the structure. The analysis itself is carried out with the aid of a structural analysis software, SAP2000 where two proposes modeling. The first for the linear effects and the second for the nonlinear effects

Sulla progettazione in zona sismica di strutture dotate di dissipatori fluido-viscosi: proposta di una metodologia

CHAPTER 1:FLUID-VISCOUS DAMPERS In this chapter the fluid-viscous dampers are introduced. The first section is focused on the technical characteristics of these devices, their mechanical behavior and the latest evolution of the technology whose they are equipped. In the second section we report the definitions and the guide lines about the design of these devices included in some international codes. In the third section the results of some experimental tests carried out by some authors on the response of these devices to external forces are discussed. On this purpose we report some technical schedules that are usually enclosed to the devices now available on the international market. In the third section we show also some analytic models proposed by various authors, which are able to describe efficiently the physical behavior of the fluid-viscous dampers. In the last section we propose some cases of application of these devices on existing structures and on new-construction structures. We show also some cases in which these devices have been revealed good for aims that lies outside the reduction of seismic actions on the structures. CHAPTER 2:DESIGN METHODS PROPOSED IN LITERATURE In this chapter the more widespread design methods proposed in literature for structures equipped by fluid-viscous dampers are introduced. In the first part the response of sdf systems in the case of harmonic external force is studied, in the last part the response in the case of random external force is discussed. In the first section the equations of motion in the case of an elastic-linear sdf system equipped with a non-linear fluid-viscous damper undergoing a harmonic force are introduced. This differential problem is analytically quite complex and it’s not possible to be solved in a closed form. Therefore some authors have proposed approximate solution methods. The more widespread methods are based on equivalence principles between a non-linear device and an equivalent linear one. Operating in this way it is possible to define an equivalent damping ratio and the problem becomes linear; the solution of the equivalent problem is well-known. In the following section two techniques of linearization, proposed by some authors in literature, are described: the first technique is based on the equivalence of the energy dissipated by the two devices and the second one is based on the equivalence of power consumption. After that we compare these two techniques by studying the response of a sdf system undergoing a harmonic force. By introducing the equivalent damping ratio we can write the equation of motion of the non-linear differential problem in an implicit form, by dividing, as usual, for the mass of the system. In this way, we get a reduction of the number of variables, by introducing the natural frequency of the system. The equation of motion written in this form has two important properties: the response is linear dependent on the amplitude of the external force and the response is dependent on the ratio of the frequency of the external harmonic force and the natural frequency of the system only, and not on their single values. All these considerations, in the last section, are extended to the case of a random external force. CHAPTER 3: DESIGN METHOD PROPOSED In this chapter the theoretical basis of the design method proposed are introduced. The need to propose a new design method for structures equipped with fluid-viscous dampers arises from the observation that the methods reported in literature are always iterative, because the response affects some parameters included in the equation of motion (such as the equivalent damping ratio). In the first section the dimensionless parameterε is introduced. This parameter has been obtained from the definition of equivalent damping ratio. The implicit form of the equation of motion is written by introducing the parameter ε, instead of the equivalent damping ratio. This new implicit equation of motions has not any terms affected by the response, so that once ε is known the response can be evaluated directly. In the second section it is discussed how the parameter ε affects some characteristics of the response: drift, velocity and base shear. All the results described till this point have been obtained by keeping the non-linearity of the behavior of the dampers. In order to get a linear formulation of the problem, that is possible to solve by using the well-known methods of the dynamics of structures, as we did before for the iterative methods by introducing the equivalent damping ratio, it is shown how the equivalent damping ratio can be evaluated from knowing the value of ε. Operating in this way, once the parameter ε is known, it is quite easy to estimate the equivalent damping ratio and to proceed with a classic linear analysis. In the last section it is shown how the parameter ε could be taken as reference for the evaluation of the convenience of using non-linear dampers instead of linear ones on the basis of the type of external force and the characteristics of the system. CHAPTER 4: MULTI-DEGREE OF FREEDOM SYSTEMS In this chapter the design methods of a elastic-linear mdf system equipped with non-linear fluidviscous dampers are introduced. It has already been shown that, in the sdf systems, the response of the structure can be evaluated through the estimation of the equivalent damping ratio (ξsd) assuming the behavior of the structure elastic-linear. We would to mention that some adjusting coefficients, to be applied to the equivalent damping ratio in order to consider the actual behavior of the structure (that is non-linear), have already been proposed in literature; such coefficients are usually expressed in terms of ductility, but their treatment is over the aims of this thesis and we does not go into further. The method usually proposed in literature is based on energy equivalence: even though this procedure has solid theoretical basis, it must necessary include some iterative process, because the expression of the equivalent damping ratio contains a term of the response. This procedure has been introduced primarily by Ramirez, Constantinou et al. in 2000. This procedure is reported in the first section and it is defined “Iterative Method”. Following the guide lines about sdf systems reported in the previous chapters, it is introduced a procedure for the assessment of the parameter ε in the case of mdf systems. Operating in this way the evaluation of the equivalent damping ratio (ξsd) can be done directly without implementing iterative processes. This procedure is defined “Direct Method” and it is reported in the second section. In the third section the two methods are analyzed by studying 4 cases of two moment-resisting steel frames undergoing real accelerogramms: the response of the system calculated by using the two methods is compared with the numerical response obtained from the software called SAP2000-NL, CSI product. In the last section a procedure to create spectra of the equivalent damping ratio, affected by the parameter ε and the natural period of the system for a fixed value of exponent α, starting from the elasticresponse spectra provided by any international code, is introduced.

Studio sulla vulnerabiltà sismica della clinica neurologica di Bologna

In questo studio di tesi è stata eseguita un' analisi storico critica sugli edifici del complesso della Clinica Neurologica di Bologna, sono state valutate le sollecitazioni attraverso una modellazione 3D con software agli elementi finiti SAP2000, e sono state eseguite le verifiche dei meccanismi di collasso globali, locali ed inoltre verifiche di deformabiltà.

Verifica di vulnerabilita' sismica del padiglione n.15 del complesso ospedaliero Sant'Orsola

Verifica di vulnerabilità sismica di una struttura in cemento armato composta da telai longitudinali e setti. La conoscenza della struttura si è basata su sopralluoghi e, non essendo in possesso di informazioni strutturali per gli elementi resistenti, sulla base di un "progetto simulato". Per ogni elemento resistente sono state svolte analisi e verifiche statiche e sismiche riscontrando una carenza degli elementi orizzontali. La modellazione è stata eseguita sia manualmente che con un programma di calcolo agli elementi finiti.

Verifiche di vulnerabilità sismica della Facolta di Fisica a Bologna

Valutazione della vulnerabilità sismica di una struttura mista in muratura e calcestruzzo armato esistente. Caratterizzazione meccanica dei materiali mediante prove diagnostiche. Modellazione strutturale attraverso un programma agli elementi finiti (SAP2000), verifiche statiche e sismiche condotte secondo le attuali normative italiane (NTC2008). Caso di studio: facoltà di Fisica a Bologna (A. Righi)

Vulnerabilità sismica di edifici in muratura: Confronti tra metodi di valutazione

Lo scopo principale di questa tesi di laurea è la valutazione della vulnerabilità sismica di un edificio esistente in muratura portante. In particolare si è esaminato il corpo Est del padiglione 19 del complesso ospedaliero San’Orsola-Malpighi di Bologna. Dopo una prima fase di conoscenza dell’edificio, attraverso sopralluoghi e tramite gli elaborati forniti dall’ufficio tecnico dell’ospedale, si è passati alla modellazione ad elementi finiti mediante il programma di calcolo Sap2000. Mediante modellazione manuale e modellazione FEM sono state eseguite prima le analisi lineari (statiche e dinamiche) e successivamente l’analisi statica non lineare. L’analisi lineare è stata condotta attraverso i tre livelli di analisi sismiche (LV1, LV2, LV3). Nel caso dell’analisi non lineare, si sono studiati prima i singoli maschi murari con modello a mensola e alla Grinter, poi pareti monopiano senza e con fasce di piano. L’analisi della struttura, infine, è stata svolta analizzando pareti multipiano soggette a due differenti distribuzioni di forze orizzontali, confrontando la domanda di spostamento, indotta dall’azione sismica, con la capacità di spostamento della struttura stessa. La tesi si conclude con considerazioni finali in merito ad analogie e differenze riscontrate nei due metodi di analisi utilizzati.

The analysis of the collapse of a precast r.c. industrial building during the 29th may 2012 emilia romagna earthquake

Analysis of the collapse of a precast r.c. industrial building during the 2012 Emilia earthquake, focus on the failure mechanisms in particular on the flexure-shear interactions. Analysis performed by a time history analysis using a FEM model with the software SAP2000. Finally a reconstruction of the collapse on the basis of the numerical data coming from the strength capacity of the elements failed, using formulation for lightly reinforced columns with high shear and bending moment.

Assessment Of Dynamic Properties Of A Crowd Model For Human-Structure Interaction Modeling

As lightweight and slender structural elements are more frequently used in the design, large scale structures become more flexible and susceptible to excessive vibrations. To ensure the functionality of the structure, dynamic properties of the occupied structure need to be estimated during the design phase. Traditional analysis method models occupants simply as an additional mass; however, research has shown that human occupants could be better modeled as an additional degree-of- freedom. In the United Kingdom, active and passive crowd models are proposed by the Joint Working Group as a result of a series of analytical and experimental research. It is expected that the crowd models would yield a more accurate estimation to the dynamic response of the occupied structure. However, experimental testing recently conducted through a graduate student project at Bucknell University indicated that the proposed passive crowd model might be inaccurate in representing the impact on the structure from the occupants. The objective of this study is to provide an assessment of the validity of the crowd models proposed by JWG through comparing the dynamic properties obtained from experimental testing data and analytical modeling results. The experimental data used in this study was collected by Firman in 2010. The analytical results were obtained by performing a time-history analysis on a finite element model of the occupied structure. The crowd models were created based on the recommendations from the JWG combined with the physical properties of the occupants during the experimental study. During this study, SAP2000 was used to create the finite element models and to implement the analysis; Matlab and ME¿scope were used to obtain the dynamic properties of the structure through processing the time-history analysis results from SAP2000. The result of this study indicates that the active crowd model could quite accurately represent the impact on the structure from occupants standing with bent knees while the passive crowd model could not properly simulate the dynamic response of the structure when occupants were standing straight or sitting on the structure. Future work related to this study involves improving the passive crowd model and evaluating the crowd models with full-scale structure models and operating data.

Respuesta sísmica de un edificio de estructuras metálica con aisladores : alternativas de diseño

El presente trabajo es un estudio teórico – experimental para la implementación de un edificio metálico de cuatro plantas con dispositivos disipadores de energía. Este estudio presenta una técnica para la generación de un registro sísmico artificial, que sea compatible con los espectros de diseño de las normas chilena y española. Este acelerograma se crea con una herramienta computacional denominada SIMQKE. La simulación de la estructura sometida al terremoto artificial se realizará en el programa de elementos finitos SAP200. El trabajo se encuentra dividido en cuatro capítulos, cuyos contenidos son los siguientes. En el capitulo uno, o estado del arte, se revisan las diferentes técnicas de aislamiento sísmico, se describe el dispositivo a utilizar, sus bases teóricas y formulación matemática, se revisan las normas NCh.2745 Of.2003 [12], NCSE-02 [18] y se presenta la técnica para la generación de un registro sintético compatible. El capítulo dos aborda el análisis experimental para un edificio real: una edificación de estructura metálica implementada con disipadores de energía metálicos y que será sometida a tres terremotos de diferente magnitud. El capítulo tres expone los resultados de los desplazamientos medidos para la estructura sin disipadores y con ellos, se presentan los porcentajes de disminución de desplazamientos relativos por planta y por tipo de estructura. Por último, el capítulo cuatro presenta las principales conclusiones y una breve discusión de los resultados. The present work is a theoretical and experimental study for the implementation of a fourstorey building with energy dissipating devices. This study presents a technique for generation an artificial seismic record, which is compatible with the design spectra Chilean and Spanish standards. This accelerogram is created with a computational tool called SIMQKE. The simulation of the structure subjected to artificial earthquake will take place in the finite element program SAP2000. This work is divided into four chapters whose contents are as follows. In chapter one, or state of the art, reviews the different seismic isolation techniques, describes the device used, theoretical and mathematical formulation, NCh2745 Of.2003 [12] and NCSE-02 [18] standards are checked, and presents the technique for generating a synthetic record compatible. Chapter two explains the experimental analysis to a real building: a building of steel structure implemented with metallic energy dissipators and will be submitted to three different earthquakes of magnitude. Chapter three presents the results of measured displacements for the structure without dissipators and with them, the percentages of decline relative displacements per plant and type of structure. Finally, chapter four presents the main conclusions and a brief discussion of the results.