Steel space frames having irregular shapes when subjected to lateral loads caused by wind or earthquakes undergo twisting as a result of their unsymmetrical topology. As a result, torsional moment comes out which is required to be resisted by the three dimensional frame system. The members of such frame are generally made out of steel I sections which are thin walled open sections. The simple beam theory is not adequate to predict behavior of such thin-walled sections under torsional moments due to the fact that the large warping deformations occur in the cross section of the member. Therefore, it is necessary to consider the effect of warping in the design of the steel space frames having members of thin walled steel sections is significant. In this study the optimum design problem of steel space frames is formulated according to the provisions of LRFD-AISC (Load and Resistance factor design of American Institute of Steel Construction) in which the effect of warping is also taken into account. Ant colony optimization and harmony search techniques two of the recent methods in stochastic search techniques are used to obtain the solution of the design problem. Number of space frame examples is designed by the algorithms developed in order to demonstrate the effect of warping in the optimum design.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A utilizaÃÃo de vigas laminadas de parede fina nas Engenharias AeronÃutica, Civil, MecÃnica e Naval tem crescido bastante nos Ãltimos anos, devido a suas elevadas relaÃÃes rigidez/peso e resistÃncia/peso. Esses elementos estruturais normalmente apresentam paredes finas devido à alta resistÃncia dos materiais compÃsitos. Outra caracterÃstica importante à que, mesmo sem apresentar grandes deformaÃÃes e sem que o limite elÃstico do material seja ultrapassado, estas vigas apresentam comportamento nÃo linear geomÃtrico devido à sua elevada esbeltez, acarretando em grandes deslocamentos e rotaÃÃes. Dependendo da laminaÃÃo utilizada, as vigas de materiais compÃsitos podem apresentar diversos acoplamentos entre esforÃos e deformaÃÃes, tornando a sua anÃlise bem mais complexa do que a anÃlise de vigas de material isotrÃpico. Neste trabalho, foram desenvolvidos dois elementos finitos de pÃrtico espacial para anÃlise nÃo linear geomÃtrica de vigas laminadas de parede fina. As propriedades seccionais da viga sÃo avaliadas atravÃs de teorias de vigas laminadas de parede fina apropriadas, em que desprezam-se os efeitos do empenamento e do cisalhamento transversal. Tais teorias de vigas laminadas conduzem a uma matriz constitutiva 4x4, onde diferentes nÃveis de acoplamento entre esforÃos e deformaÃÃes de viga sÃo considerados, por exemplo, pode-se obter uma matriz constitutiva diagonal ou cheia. A abordagem corrotacional independente do elemento à utilizada para o tratamento de grandes deslocamentos e rotaÃÃes de corpo rÃgido no espaÃo. No Ãmbito local, sÃo utilizados dois elementos, um baseado na teoria linear e outro na descriÃÃo Lagrangeana Total. O tratamento matemÃtico das grandes rotaÃÃes no espaÃo à realizado por meio do tensor das rotaÃÃes (fÃrmula de Rodrigues), juntamente com o conceito do pseudovetor. As implementaÃÃes dos elementos finitos propostos neste trabalho sÃo realizadas no software de cÃdigo aberto FAST. A metodologia de trabalho segue o roteiro clÃssico de mÃtodos computacionais, incluindo formulaÃÃo, implementaÃÃo, verificaÃÃo e validaÃÃo dos resultados. A verificaÃÃo à realizada atravÃs dos modelos tridimensionais de elementos finitos de casca e sÃlido desenvolvidos no software comercial ABAQUS. A validaÃÃo à realizada por meio da comparaÃÃo com resultados de ensaios experimentais encontrados na literatura. No que diz respeito à avaliaÃÃo das propriedades seccionais, pode-se verificar uma Ãtima concordÃncia entre as teorias de vigas laminadas adotadas neste trabalho e os resultados numÃricos e de ensaios experimentais, para todas as laminaÃÃes e carregamentos considerados. No caso dos elementos de pÃrtico espacial, verificou-se uma Ãtima concordÃncia entre os resultados dos elementos finitos propostos neste trabalho e os resultados analÃticos e computacionais disponÃveis na literatura. Observa-se tambÃm que o elemento baseado na descriÃÃo Lagrangeana à mais eficiente do que o elemento baseado na teoria linear no que tange à capacidade de apresentar uma resposta satisfatÃria com uma malha menos refinada. / The use of thin walled laminate beams in Aeronautical, Civil, Mechanical and Naval Enginee- ring is increasing in the last years. This is due to their high stiffness/weight and strength/weight ratios. Composite beams and other structural elements tend to have thin walls due to the elevated strength of the material. Other important aspect is that, even without reaching large strains and without overcoming the elastic limit of the material, such beams present geometric nonlinear behavior due to high their slenderness, leading to large displacements and rotations. Depen- ding on the composite layup, the beams of composite materials can present several couplings between generalized stresses and strains, requiring a more complex analysis procedure when compared to isotropic beams. In this work, two three-dimensional space frame finite elements that can be used to analyze composite thin-walled beams subjected to geometric non-linearity were developed. The cross-section properties of the beams are evaluated through suitable thin walled beam theories, where the effects of the warping and transverse shear are neglected. Such theories yield a 4x4 constitutive matrix for the laminate and different levels of coupling between generalized stresses and strains can be considered. Depending of such couplings, the constitu- tive matrix can either be full or diagonal. The element independent corotational approach was used in order to consider large displacaments and rigid body rotations in space. In the local coordinate system, two elements are used, one based on the linear strain theory and the other on the Total Lagrangian formulation. The mathematical treatment of the large rotations in the space is performed by means of the rotation tensor (Rodriguesâs formula) in conjunction with the concept of the pseudovector. The computational implementations of the two finite elements proposed in this work were done in the open source software FAST ( Finite Element Analysis Tool ). The methodology used follows the classical steps used in computational methods, in- cluding formulation, implementation, verification and validation of results. Such verification is accomplished through shell and solid three-dimensional finite element models developed in the ABAQUS commercial software. The validation is performed by means of comparison with the experimental results found in literature. Regarding the evaluation of cross-sectional properties, one can observe a good agreement between the laminated beam theories adopted in this work and numerical and experimental results for all composite layups and load conditions conside- red. In the case of space frame elements, a good agreement is obtained between the results of finite elements proposed in this work and the analytical and computational results available in the literature. It is also observed that the element based on the Lagrangian formulation is more efficient than the element based on the linear theory regarding the ability to provide a satisfatory response with a less refined mesh

The aim of the work is to design steel structure exhibition pavilion. The building is situated in Brno. The construction is processed in two options. The option A is designed in variant of arched space frame. The internal ground plan dimensions of the building are 42 x 72 meters. Space frame is hinged to the structure of columns. Height in the top of the ship is 16,834 metres. The option B is designed in variant arched truss. The internal ground plan dimensions of the building are 42 x 70 meters. Arched truss is hinged to the structure of columns. Height in the top of the ship is 18,334 metres. The spatial rigidity of the structure is ensured by cross braces. Roof cladding and walls will be made using sandwich panels of KINGSPAN. The main material will be used steel S235.

The objective of the diploma thesis is to design and check a load-carrying steel structure of departure lounge in Ostrava. The building has a rectangular plan with dimensions of 45x63m. Height of the building at its heightest point is 13m. First variant composes of trussed girders and purlins. Spatial rigidity is achieved by bracings. Second variant is a flat space frame. The design of joints, column anchorage and drawings has been made for variant 2.

[ES] El objetivo de esta tesis es diseñar una estructura polivalente que tiene la capacidad y los criterios a ser utilizados en situaciones de emergencia, y en los países en desarrollo, donde se deben realizar intervenciones para ayudar a superar algunos problemas de la vida. Se trata de un esqueleto principal que definirá la forma final de la estructura y se va a transformar con el fin de que se adapte a todos los climas, y a los diferentes terrenos, y a las diferentes situaciones de emergencia. Esta estructura puede ser utilizada para las escuelas y los hospitales en los países en desarrollo, para el apoyo a los refugiados, para las exposiciones temporales de recaudación de fondos... El proyecto se realizará con materiales sostenibles traídos de los alrededores de la zona de intervención con el fin de eliminar los gastos de transporte y dejar que se mezclan con su ambiente. La tecnología elegida es la del Space Frame, proporcionando una gran cobertura de espacio con un mínimo de material. La estructura es sostenible por lo que se basara únicamente en las fuentes naturales de energía para satisfacer las necesidades de los usuarios y, si es posible, crear energía adicional. La investigación y el desarrollo del proyecto se llevaron a cabo en 3 países: el estudio sostenible ha sido realizado en Italia, el desarrollo del proyecto en España, Valencia, y la recuperación de información, investigación de campo y la experimentación se llevaba a cabo en el Líbano, donde los conflictos en curso han dado lugar a un número sin precedente de refugiados allí. La tesis parte desde el estudio de la arquitectura de emergencia en general para después tratar la historia de este tema en el Líbano. Una vez entendido el contexto es más fácil traer las líneas guiadas necesarias para que este proyecto no cae en los mismos errores de los antecedentes. Llegado a este nivel, y para justificar más el proyecto y hacerlo lo más cercano de las necesidades actuales en el país, se ha hecho un largo trabajo e investigación y entrevistas en diferentes campos de refugiados. Desde esta parte se ha podido traer otras líneas guiadas para mejorar el proyecto. Con todas estas líneas guiadas, se ha adelantado el dibujo, estudio y análisis sostenible y estructural del proyecto de la tesis. / [CA] L'objectiu d'aquesta tesi és dissenyar una estructura polivalent que tingui la capacitat i els criteris a utilitzar en situacions d'emergència i en països en desenvolupament, on s'han de fer intervencions per ajudar a superar alguns problemes de vida. Es tracta d'un esquelet principal que definirà la forma final de l'estructura i es transformarà de manera que s'adapti a tots els climes i a diferents terrenys i a diferents situacions d'emergència. Aquesta estructura es pot utilitzar per a escoles i hospitals dels països en desenvolupament, per donar suport als refugiats, per a exposicions temporals de recaptació de fons... El projecte es farà amb materials sostenibles provocats per l'àrea d'intervenció per eliminar els costos de transport i deixar-los barrejar al seu entorn. La tecnologia escollida és Space Frame, proporcionant una gran cobertura espacial amb un mínim de material. L'estructura és sostenible, de manera que només es basarà en fonts d'energia naturals per satisfer les necessitats dels usuaris i, si és possible, crear energia addicional. La investigació i el desenvolupament del projecte es van dur a terme a 3 països: l'estudi sostenible es va dur a terme a Itàlia, el desenvolupament del projecte a Espanya, València i la recuperació d'informació, la investigació i l'experimentació de camp es van dur a terme al Líban, on els conflictes en curs han provocat un nombre sense precedents de refugiats. La tesi parteix de l'estudi de l'arquitectura d'emergència en general i després tracta la història d'aquest tema al Líban. Un cop entès el context, és més fàcil portar les línies guiades necessàries perquè aquest projecte no caigui en els mateixos errors que els anteriors. A aquest nivell, i per justificar encara més el projecte i fer-lo tan a prop de les necessitats actuals del país, s'han realitzat treballs extensos i investigacions i entrevistes en diferents camps de refugiats. A partir d'aquesta part ha estat possible portar altres línies guiades per millorar el projecte. Amb totes aquestes línies guiades, s'ha avançat el dibuix, l'estudi i l'anàlisi sostenible i estructural del projecte de tesi. / [EN] The objective of this thesis is to design a multipurpose structure that has the capacity and criteria to be used in emergency situations, and in developing countries, where interventions must be made to help overcome some life problems. This is a main skeleton that will define the final shape of the structure and will be transformed so that it adapts to all climates, and to different terrains, and to different emergency situations. This structure can be used for schools and hospitals in developing countries, for supporting refugees, for temporary fundraising exhibitions... The project will be made with sustainable materials brought from around the area of intervention in order to eliminate transportation costs and let them blend into their environment. The technology chosen is Space Frame, providing great space coverage with a minimum of material. The structure is sustainable so it will rely solely on natural energy sources to meet the needs of users and, if possible, create additional energy. The research and development of the project was carried out in 3 countries: the sustainable study was carried out in Italy, the development of the project in Spain, Valencia, and the information retrieval, field research and experimentation was carried out in Lebanon, where ongoing conflicts have led to unprecedented numbers of refugees there. The thesis starts from the study of emergency architecture in general and then deals with the history of this topic in Lebanon. Once the context is understood, it is easier to bring the necessary guided lines so that this project does not fall into the same errors as the previous ones. At this level, and to further justify the project and make it as close to the current needs in the country, extensive work and research and interviews have been done in different refugee camps. From this part it has been possible to bring other guided lines to improve the project. With all these lines guided, the drawing, study and sustainable and structural analysis of the thesis project has been advanced. / Jaber, N. (2024). Study and analysis of the behavior of a construction system for sustainable architecture [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/206180

High performance multifunctional epoxy resin systems are becoming increasingly important as matrix materials for the advanced composites used in aerospace, electronics, automotive and other industries. In a composite based on epoxy resin systems, a three-dimensional network of the matrix is formed around the reinforcing fibre as a result of the chemical reaction between the resin and the curing agent. This chemical process, known as curing, is an important event to he considered in the production of composite components made up of these resin systems. Two process parameters namely viscosity and chemical conversion are of paramount significance in the production of composite materials Curing studies of the resin systems based on these two parameters, would therefore assume great importance in deciding the performance reliability of the end product. The objectives of the present investigation are 1. to study the cure kinetics of three thermoset resin systems, viz., i) epoxy novolac (EPIT)/ diamino diphenyl methane{DDM), ii) trigylcidyl para- ammo phenol (TGPAP)/toluene diamine (TDA) and iii) tetraglycidyl diamino diphenyl methane (TGDDM)/pyridine diamine(PDA) using the cure kinetic models based on chemical conversion (α), Theological conversion (β) and viscosity. 2.to develop a correlation between a and viscosity (η) and modify an existing autocatalytic model based on α, to the viscosity domain and 3.to investigate the cure behaviour of these systems in terms of the TTT cure diagram and its associated models. EPN/DDM, TGPAP/PDA and TGDDM/PDA resin systems were chosen for the studies to represent a range of functionalities, The cure was monitored using differential scanning calorimetry (DSC), fourier transform infrared (FTIR) and dynamic mechanical analysis (DMA) techniques by following the changes in enthalpy, functional groups and rheology, respectively. The kinetic parameters namely, order of reaction and activation energy were estimated from dynamic DSC data using the methods of Freeman-Carroll and Ellerstein using nth rate expression. Barton, Kissinger and Osawa methods were employed to find out the activation energy from the peak/equal conversion at different heating rates. Isothermal DSC data were also analyzed using nth order model and it was observed that the data could be fitted satisfactorily only for higher temperatures The results obtained from the analysis of both dynamic and isothermal DSC data using nth order model clearly indicate that this model is inadequate for describing the cure behavior. The isothermal DSC data was analyzed by the autocatalytic models of Hone and Kamal Good correlation was observed with Hum and Kamal models up to 60-70%, 25% and 45% conversions for EPN/DDM, TGPAP/TDA and TCDDM/PDA systems respectively. However, the parameters m and n in Kamal model were found to be temperature dependent for EPN/DDM and TCPAP/TDA systems. The limited applicability of the autocatalytic models IK attributed to the counter-effect offered by the intra-molecular bonding taking place. The primary amine and epoxy groups conversions obtained from FTIR were analyzed using autocatalytic model and the kinetic parameters were calculated. The reactivity ratio of the primary amine and the secondary amine with epoxy was found to be dependent on temperature in agreement with the recent findings reported m the literature. The existing models that relate the cure kinetics and the rheological changes, are dual Arrhenius nth order model and autocatalytic model The nth order kinetic model was used to evaluate the kinetic parameters using the viscosity data at different cure temperatures under isothermal conditions As the storage modulus, G' is proportional to the chemical cross links and becomes significant only after the g<4 point, it was used to follow the changes in conversion known as rheoconversion after the gel point The rheoconversion was found by normalizing the G' data with G1^, the storage modulus of the fully cured resin It was used to study the cuie kinetics using an autocatalytic model The kinetic parameters such as rate constant, acceptation and retardation parameters were evaluated and that temperature dependence was established. While the existing models relate viscosity and conversion only up to gel point the new proposed model, termed VISCON model takes into account the changes up to vitrification. The relation so developed is used to modify the autocatalytic cure model based on chemical conversion. The parameters appearing in this model were evaluated using Levenberg-Marquardt error minimization algorithm. The kinetic parameters obtained are comparable with the values estimated using the DSC data. All the models cited above represent the microkinetic aspects. The models based on the information of TTT cure diagrams, however, represent the macrokinetic aspects of the cure, as they are based on the cure stages such as gelation and vitrification TTT diagram relates the cure characteristics like cure temperature, cure time, Ta and, indirectly, chemical conversion Hence the ultimate properties of the composite could he predicted and established with the help of the models based on TTT cure diagrams The changes in the storage modulus, G1 and loss modulus, G", were followed to identify the gel and vitrification points of the resin systems at different cure temperatures Gel point and vitrification point were used to generate gelation and vitrification hues in the construction of TTT cure diagrams for EPN/DDM, TGPAP/TDA and TGDDM/PDA resin systems Theoretical TTT diagrams were generated and IBO-T, contours were established using the TTT diagram-based models The cure schedule for the resin systems investigated could be determined from the TTT diagram and the respective rheological data.

Cette thèse s'inscrit dans la continuation du travail de Younes Achkire, consacré au contrôle actif des ponts haubanés. Elle traite de l'implémentation d'un système de contrôle actif sur des maquettes de structures câblées. Deux types de structures sont étudiés expérimentalement: les ponts haubanés et les treillis spatiaux. Après une brève introduction sur l'usage du contrôle actif dans ces domaines, le chapitre 2 traite numériquement des mécanismes d'interaction entre le câble et la structure. Au chapitre 3, nous présentons la stratégie de contrôle que nous utilisons pour stabiliser une structure câblée: il s'agit d'un contrôle décentralisé, basé sur des paires capteur/actionneur colocalisées, placées au niveau des ancrages des câbles, chacune équipée d'un contrôleur Intégral Force Feedback. Nous présentons une théorie linéaire simplifiée permettant de dimensionner le système et de prévoir son efficacité. Elle est illustrée sur un exemple, et nous discutons de la validité de certaines hypothèses simplificatrices. Le chapitre 4 est consacré au contrôle actif des ponts haubanés. Nous y présentons 2 maquettes. La première, de petite taille (3m) représente un pylône de pont haubané en construction. Elle est équipée d'actionneurs piézoélectriques. La seconde, installée au Centre Commun de Recherche d'Ispra (Italie), mesure 30m de long, et est équipée d'actionneurs hydrauliques. Les expériences réalisées sur ces maquettes ont démontré l'efficacité du contrôle et la fiabilité de la théorie prédictive. Le contrôle du flottement des ponts est traité sur un exemple numérique. Le chapitre 5 relate nos expériences d'amortissement actif des treillis spatiaux. Deux structures ont été étudiées: une colonne en treillis équipée de 3 câbles actifs, et une structure triédrique suspendue à des cordons élastiques pour simuler l'absence de gravité, également munie de câbles actifs. Deux concepts d'actionneur piézoélectrique ont été testés. Nous avons ensuite examiné le problème de la saturation des actionneurs, et celui du contrôle actif des microvibrations (~10nm) d'une structure câblée. Le chapitre 6 conclut ce travail, en souligne les aspects originaux et donne quelques perspectives de développement. / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

Spacecrafts are generally equipped with high precision optical and other sensor payloads. The structures of most of the spacecrafts are light-weight, flexible and have low damping. Vibrations are often induced in the spacecraft body due to the presence of many disturbance sources such as momentum/reaction wheels, control thrusters used for attitude control and cryocoolers etc. Low damping leads to long decay time for vibrations hence during this period the spacecraft sensors cannot be used effectively. One possible solution is to isolate the precision sensor from the rest of the satellite and this strategy has been used for spaceborne telescopes and interferometers that have extremely precise positional and vibratory tolerances imposed on them in order to achieve scientific goals. Another strategy is to isolate the vibration source itself from the spacecraft body. This thesis deals with modelling, analysis and experimentation of a novel low frequency flexible space platform designed to serve as a mount for the disturbance source in order to insulate the source generated vibrations reaching critical areas of the structure. The novel space platform consisting of folded continuous beams, is light-weight and is capable of isolating vibration generated by sources such as reaction/momentum wheels. Finite element analysis of the platform is carried out for static and dynamic load cases. Simulation studies are carried out on flexible beam platform in order to firm up the design for passive vibration isolation. Modal analyses is done to simulate the response of each mode. Active control has been studied by embedding the platform’s beam elements with piezo actuators and sensors. The simulation results show that the space platform can effectively attenuate vibration and further improvement in vibration attenuation is possible with active control. Based on the analysis, a prototype low frequency platform has been designed and fabricated. An experimental validation has been done to test the usefulness of the low frequency platform to act as a mount for reaction wheels and to mitigate the vibration disturbances/effects transmitted from the reaction wheel assembly to structure. Measurements and tests have been conducted at varying wheel speeds to quantify and characterize the amount of isolation to the reaction wheel generated vibrations. The time and frequency domain analysis of test data clearly show that level of isolation is significant and an average of 13 dB of isolation is seen. The level of isolation is different for different isolators and it depends upon the isolator design and wheel speed. Forces and moments measured at the base for wheel with isolator and wheel without isolator clearly demonstrate and confirm a reduction in the disturbance levels of atleast one order. These isolators are further tested successfully for launch dynamic loads in order to confirm the design adequacy to sustain such loads. Results indicate that the flexible mounts of the type discussed in this thesis can be used for effective passive vibration isolation in spacecrafts with reaction/momentum wheels.

The work is focused on assessing the structure of urban winter stadium, which will be located in Brno - Komarov. Winter stadium is designed according to standarts of ice hockey with a capacity of approximately 7 000 spectators. Of the 5 850 seating, 1 050 stalls and 100 in the VIP areas. Construction of hockey stadium is made of steel and steel-concrete columns, which together with composit transverse beam, reinforced concrete slab and bracings provide rigidity. Columns are supported by a set of bored piles with capitals. Roofing of the main part of the winter stadium is designed using a flat space frame having a maximum height of 4,5 m. Roof for entrance halls are design by a system of truss girder and purlins, which are hardened bracings to increase spatial rigidity. The structures are made of steel S 355 and concrete C 25/30. For designing steel structures was used software Scia ENGINEER and IDEA RS. Steel columns and composit beams are calculated by hand calculation. The total length of the hockey stadium is 111,5 meters, width outside the entrance hall is 82,02 m and the total width at the entrance hall is 96,85 m. The height of the building at the highest point is 25,6 meters.

The topic of the Diploma thesis is a design of the New train station in Brno. The plot is located on the boundary of three city districts – Komárov, Štýřice and Trnitá. This area includes the railway structure for the new train station and also its public spaces, which are very close to the river Svratka. The railway structure is designed as bridge construction, that rises all platforms and rail tracks to 7,65 metres above the ground level. So all of the railways do not become a barrier in the city. The main concept extends a longitudinal axis of the city boulevard through the train station, which creates a high-rise building in the southern part of the plot. This axis is written not only to the layout but also to the roof design. The train station includes two underground levels, ground floor and first floor. Underground levels consist of P+R parking, deliveries only area, technical facilities and subway terminal. The ground floor is the main traffic centre. There is an entrance hall, shopping area, bus terminal and public corridors. The first floor includes platforms for train departures and arrivals. There are also public spaces in the entrance hall. The basic structural system consists of two parts. The first part is a massive reinforced concrete structure of the railway bridge deck and all underground levels. This structure is based on reinforced concrete foundation pads with drilled piles. The second part is a steel frame structure of the roof. That includes steel columns and truss girders for the structure of the lower area. The higher part of the roof is designed as a steel-truss bridge with the characteristic profile. The new train station supposes to create a new gate to the city of Brno, that connects contemporary districts with the historical city center.