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The application of composite action ushered a new era in the use of double-layer spaceframes as efficient floor systems in addition to their competitiveness as roof coveringstructural systems. Earlier research on space frames demonstrated large improvementsin their static behaviour caused by the introduction of composite action. Theseimprovements included an increase in ductility to avoid progressive collapse, a largeincrease in load-carrying capacity and a considerable reduction in materialconsumption.In this work, the effect of introducing composite action in changing the dynamiccharacteristics of space frames, in particular the natural frequencies and damping ratioswas presented. The study was expanded to determine the effect of composite action inchanging the response to dynamic excitations. The measured responses included thelateral displacements and changes in the internal member force distribution undershaking table vibrations.Three aluminium space frame models of the square on square (SOS) configuration weremanufactured. The first model was non-composite, while composite action was appliedto the other two models with a top aluminium deck and a timber deck, respectively.Two common cases of support conditions were used in connecting the models to theloading frame, which was the platform of the shaking table.Initial displacement method (snap test) was used to determine the frequency of vibrationand the damping ratio of test models in the vertical and horizontal directions usinglogarithmic decrement method. All models were then exposed to shaking tablevibrations to determine the changes in dynamic responses between different models.These tests were repeated for the three models after the successive removal of panelsfrom one direction to identify the changes to their characteristics and behaviour withdifferent aspect ratios.The second part of the study was carried out numerically by using the finite elementpackage ABAQUS. It started by selecting a valid finite element model from nineproposed models using experimental test results on physical structures. A parametricstudy was conducted using the validated finite element model to expand the study toinclude two common space frame configurations; the square on large square (SOLS)and square on diagonal (SOD), and two other cases of support configurations, namely,fully edge-supported and supports at corners and middle edges of models.Based on the work done in this study, it can be concluded that composite actionchanged the dynamic characteristics of space frames, which was clear in the increase oftheir vibration frequencies in all directions as a result of the increase in stiffness.Furthermore, the increase in stiffness resulted in a general reduction in the dampingratio of space frames covered with aluminium deck, while the high friction with topjoints and the nature of timber as a good energy absorbent material resulted in a variableeffect on the damping ratio associated with the increase in aspect ratio.The effect of composite action was clear in reducing the lateral displacement ofcomposite models by more than 50% compared to the non-composite case. Moreover,composite action resulted in changing the distribution of internal forces in diagonal andlower chord members such that forces became more concentrated at corners and edgesparallel to the direction of vibrations in both cases of corner and edge-supportedmodels.

Este trabalho apresenta um estudo sobre o comportamento de treliças espaciais formadas por elementos tubulares de seção circular, com ênfase no desempenho das tipologias de ligação utilizadas no Brasil. Foram ensaiadas experimentalmente 9 treliças espaciais com vãos de 7,5 x 15,0m e uma de 7,5m x 7,5m com altura de 1,5m, variando-se o tipo de ligação entre barras, com o objetivo de caracterizar e comparar o comportamento dos sistemas de ligações mais comuns (nó típico – extremidade estampada, nó de aço e nó com chapa de ponteira).A análise teórica, via elementos finitos, tem como objetivo aferir a validade dos modelos numéricos normalmente utilizados e refiná-los incluindo as características do comportamento estrutural observadas em ensaio. A análise numérica segue duas abordagens: análise global da estrutura incluindo os efeitos não-lineares, excentricidade na ligação e variação de seção nas extremidades das barras; com isso o comportamento das treliças ensaiadas foi representado de forma satisfatória. A análise do comportamento do nó típico, modelado tridimensionalmente com elementos de casca, possibilitou analisar a interação entre as barras na região nodal por meio de elementos de contato. Com esta modelagem, apesar das simplificações, foi possível reproduzir o modo de colapso observado experimentalmente. / This paper presents a study of the behavior of tubular circular section space trusses with the main emphasis placed on the performance of the various truss typologies used in Brazil. Nine space trusses with plan dimensions of 7.5m x 15.0m and one with plan dimensions of 7.5mx7.5m and height of 1.5m were tested. The joint type was varied with the objective to characterize and compare the behavior of the more common types of connection systems (typical node – stamped end, steel node, and end plate node). The theoretical analysis employing finite elements was adopted mainly to ascertain the validity of various numerical models commonly employed and hence refining them by including the some basic characteristics of the observed structural behavior.The numerical analysis employed was based on two methodologies: a global structural analysis that takes into account the effects of non-linearity, eccentricities at connection, and the variation of the end bars cross section. In this manner the actual behavior of the tested trusses was well represented. The analysis of the behavior of a typical node, modeled using tri-dimensional finite shell elements made it possible to analyze the interaction between bars that converge at the nodal region by applying contact elements. Despite it simplicity, predicted results of the collapse mode obtained by using the proposed model, very well reproduce the experimental observation.

Este trabalho apresenta um estudo sobre o comportamento de treliças espaciais formadas por elementos tubulares de seção circular, com ênfase no desempenho das tipologias de ligação utilizadas no Brasil. Foram ensaiadas experimentalmente 9 treliças espaciais com vãos de 7,5 x 15,0m e uma de 7,5m x 7,5m com altura de 1,5m, variando-se o tipo de ligação entre barras, com o objetivo de caracterizar e comparar o comportamento dos sistemas de ligações mais comuns (nó típico – extremidade estampada, nó de aço e nó com chapa de ponteira).A análise teórica, via elementos finitos, tem como objetivo aferir a validade dos modelos numéricos normalmente utilizados e refiná-los incluindo as características do comportamento estrutural observadas em ensaio. A análise numérica segue duas abordagens: análise global da estrutura incluindo os efeitos não-lineares, excentricidade na ligação e variação de seção nas extremidades das barras; com isso o comportamento das treliças ensaiadas foi representado de forma satisfatória. A análise do comportamento do nó típico, modelado tridimensionalmente com elementos de casca, possibilitou analisar a interação entre as barras na região nodal por meio de elementos de contato. Com esta modelagem, apesar das simplificações, foi possível reproduzir o modo de colapso observado experimentalmente. / This paper presents a study of the behavior of tubular circular section space trusses with the main emphasis placed on the performance of the various truss typologies used in Brazil. Nine space trusses with plan dimensions of 7.5m x 15.0m and one with plan dimensions of 7.5mx7.5m and height of 1.5m were tested. The joint type was varied with the objective to characterize and compare the behavior of the more common types of connection systems (typical node – stamped end, steel node, and end plate node). The theoretical analysis employing finite elements was adopted mainly to ascertain the validity of various numerical models commonly employed and hence refining them by including the some basic characteristics of the observed structural behavior.The numerical analysis employed was based on two methodologies: a global structural analysis that takes into account the effects of non-linearity, eccentricities at connection, and the variation of the end bars cross section. In this manner the actual behavior of the tested trusses was well represented. The analysis of the behavior of a typical node, modeled using tri-dimensional finite shell elements made it possible to analyze the interaction between bars that converge at the nodal region by applying contact elements. Despite it simplicity, predicted results of the collapse mode obtained by using the proposed model, very well reproduce the experimental observation.

This research focuses on the development of the semantic and fiducial aided graph simultaneous localization and mapping (SF-GraphSLAM) method that is tailored for robotic assembly and servicing of large truss structures. SF-GraphSLAM contributes to the state of the art by creating a novel way to add associations between map landmarks, in this scenario fiducials, by pre-generating a semantic map of expected relations based on the truss module known models, kinematic information about deployable modules, and hardware constraints for assembled modules. This additional information about the expected fiducial relations, and therefore truss module relative poses, can be used to add robustness to camera pose and measurement error. In parallel, the concept of a mixed assembly truss structure paradigm was created and analyzed. This mixed assembly method focuses on reducing the number of modules required to construct large truss structures by using a mixture of deployable and assembled truss modules to create a checkerboard array that is scalable to various dimensions and shapes while still minimizing the number of modules compared to a strut-by-strut method. Leveraging this paradigm SF-GraphSLAM is able to start at an advantage in terms of minimizing the state vector for the assembly testing. In addition, due to the added knowledge of the structure and the choice to utilize fiducial markers, SF-GraphSLAM is able to minimize the number of fiducials used to define the structure and therefore have the minimum state space to solve the assembly scenario, greatly improving the real-time estimation process between assembly steps. These optimizations will have a larger effect as the size of the scaled end structure increases. SF-GraphSLAM is derived in mathematical form following the same core process used for the pose and measurement components used in the base GraphSLAM. SF-GraphSLAM is evaluated against the state of the art example of GraphSLAM through simulation using an example 3x3x3 mixed assembly truss structure, known as the Built On-orbit Robotically-assembled Gigatruss (BORG). A physical BORG test truss was constructed to enable hardware trials of the SF-GraphSLAM algorithm. Although this ground hardware is not ideal for the high precision application of space structures it allows for rapid experimental robotic testing. This tailored SF-GraphSLAM approach will contribute to the state of the art of robotic in-space servicing, assembly, and manufacturing (ISAM) by providing progress on a method for dealing with the autonomous robotic assembly of movable modules to create larger structures. This will be critical for missions such as robotically assembling a large antenna structure or space telescope. Furthermore, the core methodology will study into how to best utilize information in a large-scale structure environment, including non-static flexible or deployable modules, to adequately map it which is also applicable to the larger field of robotic operations dealing with structures such as bridge surveying. / Doctor of Philosophy / The goal of this research is to enable in-space assembly of large truss structures by advancing the state of the art of how a robot can map the structure it is actively assembling. The concept of having a robot create a map of the landmarks, or in this case truss elements, it sees while keeping track of it's own movement is known as simultaneous localization and mapping (SLAM). This research focuses on the creation of a method called semantic and fiducial aided graph simultaneous localization and mapping (SF-GraphSLAM). The added semantic information is the model knowledge of the truss structure the robot is assembling, including what kind of modules are within and their desired relationships to each other. Fiducials are optical markers that can be used to provide identification, position, and orientation of what they are mounted to. Combining these concepts SF-GraphSLAM can use easily identifiable fiducials to mark components of the truss structure and use knowledge of how the truss structure should be assembled to help in estimating where the actual physical components are at different stages of the assembly process. This method is used to check if a truss module is assembled correctly after each step to ensure the final structure is within the requirements desired. This concept can be likened to when assembling a LEGO model, a person verifies they are using the correct brick for the next assembly step and then compared the state of the model with the reference photo before proceeding with the building. An incorrectly assembled module in an early step could result in a module down the line not being able to be properly placed or the final assembled structure not being within operational tolerances. This research shows how SF-GraphSLAM can be implemented for the application of assembling a truss structure out of both deployable and assembled modules. Mathematical analysis, simulations, and hardware testing were completed to compare this new method to the state of the art approach. SF-GraphSLAM is a critical step in the development required to make autonomous robotic assembly of larger structures in space feasible.

As treliças espaciais vêm sendo freqüentemente utilizadas, de forma bastante diversificada, mas seu principal uso é como cobertura de grande vãos. Recentemente, vários acidentes com este tipo de estrutura têm acontecido, principalmente devido a uma série de considerações adotadas para dimensionamento, as quais não condizem com a realidade. Neste contexto, foi feito um estudo do comportamento seguido por estas estruturas. Este trabalho apresenta uma análise teórica, via método dos elementos finitos, de modelos de treliça espacial de seção tubular circular. Tem como objetivo verificar o comportamento de cada sistema de ligação, modelado tridimensionalmente com elementos de casca, associado à treliça espacial, modelada em elementos lineares. Foram estudadas as tipologias usuais de ligação deste tipo de estrutura abordando os problemas causados pelas peculiaridades de cada sistema. / Space trusses have been very frequently used in many applications, but its main employment is as roofs of great areas. Recently, many accidents have been occurring with this type of structure, mainly because of a series of adopted design assumptions, which does not fit reality. In this context, the behavior of this type of structure was studied. This study presents a theoretical analysis, using finite element method, of space trusses composed by circular tubular sections. It has as an objective to verify the behavior of each connection system, modeled in 3D by shell finite elements, associated to a space truss, modeled in linear finite elements. The usual typology of connections used in this kind of structure was studied, considering the problems caused by peculiarities of each system.

As treliças espaciais vêm sendo freqüentemente utilizadas, de forma bastante diversificada, mas seu principal uso é como cobertura de grande vãos. Recentemente, vários acidentes com este tipo de estrutura têm acontecido, principalmente devido a uma série de considerações adotadas para dimensionamento, as quais não condizem com a realidade. Neste contexto, foi feito um estudo do comportamento seguido por estas estruturas. Este trabalho apresenta uma análise teórica, via método dos elementos finitos, de modelos de treliça espacial de seção tubular circular. Tem como objetivo verificar o comportamento de cada sistema de ligação, modelado tridimensionalmente com elementos de casca, associado à treliça espacial, modelada em elementos lineares. Foram estudadas as tipologias usuais de ligação deste tipo de estrutura abordando os problemas causados pelas peculiaridades de cada sistema. / Space trusses have been very frequently used in many applications, but its main employment is as roofs of great areas. Recently, many accidents have been occurring with this type of structure, mainly because of a series of adopted design assumptions, which does not fit reality. In this context, the behavior of this type of structure was studied. This study presents a theoretical analysis, using finite element method, of space trusses composed by circular tubular sections. It has as an objective to verify the behavior of each connection system, modeled in 3D by shell finite elements, associated to a space truss, modeled in linear finite elements. The usual typology of connections used in this kind of structure was studied, considering the problems caused by peculiarities of each system.