As de torres treliçadas estaiadas são muito utilizadas e são foco de atenção na pesquisa da engenharia moderna, apresentando-se como um desafio na avaliação das excitações que sobre elas atuam, assim como a determinação das respostas dos elementos que as compõem. Para realizar um estudo neste sentido se realiza no presente trabalho a avaliação estrutural de uma torre treliçada estaiada, localizada na Universidade de Passo Fundo. Esta torre se encontra instrumentada, registrando velocidades de vento de forma contínua, sendo possível determinar nos registros existentes ventos característicos de tormentas TS e EPS. Se conta também com a caracterização dinâmica desta torre para qual foram determinadas suas freqüências naturais de vibração. Utilizando a informação supracitada foram criados modelos estruturais de diferentes níveis de complexidade que foram calibrados utilizando as informações disponíveis. A excitação devida a tormentas foi montada, comparando espectros de excitação clássicos disponíveis na literatura técnica e os registros experimentais de tormentas reais disponíveis. Também foi analisado um montante da torre submetido à compressão onde sua seção transversal é uma cantoneira de abas iguais. Foi determinada a carga de colapso deste perfil considerando as não linearidades físicas e geométricas incorporadas no mesmo. Foi prestada singular atenção ao estudo da influência das imperfeições, utilizando para isto expressões propostas pela bibliografia especializada e o quadro de imperfeições que foi extraído do escaneamento tridimensional de um montante real. Finalmente os diferentes aspectos estudados são discutidos nesta dissertação os quais permitem conhecer melhor o comportamento estrutural de torres estaiadas, em forma global, dos componentes que as compõem e das solicitações que atuam sobre elas. A forma em que se estudaram estes aspectos sem duvida enriqueceram a discussão do complexo tema da incerteza de modelo um dos atuais frentes na pesquisa da engenharia moderna. / The analysis of frames guyed masts are widely used and are the focus of attention in the research of modern engineering, presenting a challenge in the evaluation of excitations that act on them, and determining the responses of the component elements. To undertake a study to that effect, in this essay is made the evaluation of a structural truss of guyed masts, located at the University of Passo Fundo. This tower has equipments that record wind speeds in a continuous manner, being able to determine data about TS and EPS storms in the existing records. It also determines the natural frequencies of vibration as a dynamic characteristic of the tower. Using the above information, structural models of different levels of complexity were created, being calibrated using the available data. The excitement caused by storms was created by comparing the excitation spectra classics available in the technical literature and the experimental records of actual storms available. Also discussed was an amount subject to compression of the tower where its cross section is a corner of tabs equal. Was determined from the load profile given the collapse of physical and geometric nonlinearities embedded in it. Individual attention was given to the study of the influence of imperfections, using it to expressions proposed by the specialized literature and the framework of imperfection that was extracted from three-dimensional scanning of an actual amount.

As de torres treliçadas estaiadas são muito utilizadas e são foco de atenção na pesquisa da engenharia moderna, apresentando-se como um desafio na avaliação das excitações que sobre elas atuam, assim como a determinação das respostas dos elementos que as compõem. Para realizar um estudo neste sentido se realiza no presente trabalho a avaliação estrutural de uma torre treliçada estaiada, localizada na Universidade de Passo Fundo. Esta torre se encontra instrumentada, registrando velocidades de vento de forma contínua, sendo possível determinar nos registros existentes ventos característicos de tormentas TS e EPS. Se conta também com a caracterização dinâmica desta torre para qual foram determinadas suas freqüências naturais de vibração. Utilizando a informação supracitada foram criados modelos estruturais de diferentes níveis de complexidade que foram calibrados utilizando as informações disponíveis. A excitação devida a tormentas foi montada, comparando espectros de excitação clássicos disponíveis na literatura técnica e os registros experimentais de tormentas reais disponíveis. Também foi analisado um montante da torre submetido à compressão onde sua seção transversal é uma cantoneira de abas iguais. Foi determinada a carga de colapso deste perfil considerando as não linearidades físicas e geométricas incorporadas no mesmo. Foi prestada singular atenção ao estudo da influência das imperfeições, utilizando para isto expressões propostas pela bibliografia especializada e o quadro de imperfeições que foi extraído do escaneamento tridimensional de um montante real. Finalmente os diferentes aspectos estudados são discutidos nesta dissertação os quais permitem conhecer melhor o comportamento estrutural de torres estaiadas, em forma global, dos componentes que as compõem e das solicitações que atuam sobre elas. A forma em que se estudaram estes aspectos sem duvida enriqueceram a discussão do complexo tema da incerteza de modelo um dos atuais frentes na pesquisa da engenharia moderna. / The analysis of frames guyed masts are widely used and are the focus of attention in the research of modern engineering, presenting a challenge in the evaluation of excitations that act on them, and determining the responses of the component elements. To undertake a study to that effect, in this essay is made the evaluation of a structural truss of guyed masts, located at the University of Passo Fundo. This tower has equipments that record wind speeds in a continuous manner, being able to determine data about TS and EPS storms in the existing records. It also determines the natural frequencies of vibration as a dynamic characteristic of the tower. Using the above information, structural models of different levels of complexity were created, being calibrated using the available data. The excitement caused by storms was created by comparing the excitation spectra classics available in the technical literature and the experimental records of actual storms available. Also discussed was an amount subject to compression of the tower where its cross section is a corner of tabs equal. Was determined from the load profile given the collapse of physical and geometric nonlinearities embedded in it. Individual attention was given to the study of the influence of imperfections, using it to expressions proposed by the specialized literature and the framework of imperfection that was extracted from three-dimensional scanning of an actual amount.

As de torres treliçadas estaiadas são muito utilizadas e são foco de atenção na pesquisa da engenharia moderna, apresentando-se como um desafio na avaliação das excitações que sobre elas atuam, assim como a determinação das respostas dos elementos que as compõem. Para realizar um estudo neste sentido se realiza no presente trabalho a avaliação estrutural de uma torre treliçada estaiada, localizada na Universidade de Passo Fundo. Esta torre se encontra instrumentada, registrando velocidades de vento de forma contínua, sendo possível determinar nos registros existentes ventos característicos de tormentas TS e EPS. Se conta também com a caracterização dinâmica desta torre para qual foram determinadas suas freqüências naturais de vibração. Utilizando a informação supracitada foram criados modelos estruturais de diferentes níveis de complexidade que foram calibrados utilizando as informações disponíveis. A excitação devida a tormentas foi montada, comparando espectros de excitação clássicos disponíveis na literatura técnica e os registros experimentais de tormentas reais disponíveis. Também foi analisado um montante da torre submetido à compressão onde sua seção transversal é uma cantoneira de abas iguais. Foi determinada a carga de colapso deste perfil considerando as não linearidades físicas e geométricas incorporadas no mesmo. Foi prestada singular atenção ao estudo da influência das imperfeições, utilizando para isto expressões propostas pela bibliografia especializada e o quadro de imperfeições que foi extraído do escaneamento tridimensional de um montante real. Finalmente os diferentes aspectos estudados são discutidos nesta dissertação os quais permitem conhecer melhor o comportamento estrutural de torres estaiadas, em forma global, dos componentes que as compõem e das solicitações que atuam sobre elas. A forma em que se estudaram estes aspectos sem duvida enriqueceram a discussão do complexo tema da incerteza de modelo um dos atuais frentes na pesquisa da engenharia moderna. / The analysis of frames guyed masts are widely used and are the focus of attention in the research of modern engineering, presenting a challenge in the evaluation of excitations that act on them, and determining the responses of the component elements. To undertake a study to that effect, in this essay is made the evaluation of a structural truss of guyed masts, located at the University of Passo Fundo. This tower has equipments that record wind speeds in a continuous manner, being able to determine data about TS and EPS storms in the existing records. It also determines the natural frequencies of vibration as a dynamic characteristic of the tower. Using the above information, structural models of different levels of complexity were created, being calibrated using the available data. The excitement caused by storms was created by comparing the excitation spectra classics available in the technical literature and the experimental records of actual storms available. Also discussed was an amount subject to compression of the tower where its cross section is a corner of tabs equal. Was determined from the load profile given the collapse of physical and geometric nonlinearities embedded in it. Individual attention was given to the study of the influence of imperfections, using it to expressions proposed by the specialized literature and the framework of imperfection that was extracted from three-dimensional scanning of an actual amount.

This paper uses Bayesian model comparison methods to simultaneously specify both the spatial weight structure and explanatory variables for a spatial growth regression involving 255 NUTS 2 regions across 25 European countries. In addition, a correct interpretation of the spatial regression parameter estimates that takes into account the simultaneous feed- back nature of the spatial autoregressive model is provided. Our findings indicate that incorporating model uncertainty in conjunction with appropriate parameter interpretation decreased the importance of explanatory variables traditionally thought to exert an important influence on regional income growth rates. (authors' abstract)

Uncertainty Quantification (UQ) has been an active area of research in recent years with a wide range of applications in data and imaging sciences. In many problems, the source of uncertainty stems from an unknown parameter in the model. In physical and engineering systems for example, the parameters of the partial differential equation (PDE) that model the observed data may be unknown or incompletely specified. In such cases, one may use a probabilistic description based on prior information and formulate a forward UQ problem of characterising the uncertainty in the PDE solution and observations in response to that in the parameters. Conversely, inverse UQ encompasses the statistical estimation of the unknown parameters from the available observations, which can be cast as a Bayesian inverse problem. The contributions of the thesis focus on examining the aforementioned forward and inverse UQ problems for the low-frequency, time-harmonic Maxwell equations, where the model uncertainty emanates from the lack of knowledge of the material conductivity parameter. The motivation comes from the Controlled-Source Electromagnetic Method (CSEM) that aims to detect and image hydrocarbon reservoirs by using electromagnetic field (EM) measurements to obtain information about the conductivity profile of the sub-seabed. Traditionally, algorithms for deterministic models have been employed to solve the inverse problem in CSEM by optimisation and regularisation methods, which aside from the image reconstruction provide no quantitative information on the credibility of its features. This work employs instead stochastic models where the conductivity is represented as a lognormal random field, with the objective of providing a more informative characterisation of the model observables and the unknown parameters. The variational formulation of these stochastic models is analysed and proved to be well-posed under suitable assumptions. For computational purposes the stochastic formulation is recast as a deterministic, parametric problem with distributed uncertainty, which leads to an infinite-dimensional integration problem with respect to the prior and posterior measure. One of the main challenges is thus the approximation of these integrals, with the standard choice being some variant of the Monte-Carlo (MC) method. However, such methods typically fail to take advantage of the intrinsic properties of the model and suffer from unsatisfactory convergence rates. Based on recently developed theory on high-dimensional approximation, this thesis advocates the use of Sparse Quadrature (SQ) to tackle the integration problem. For the models considered here and under certain assumptions, we prove that for forward UQ, Sparse Quadrature can attain dimension-independent convergence rates that out-perform MC. Typical CSEM models are large-scale and thus additional effort is made in this work to reduce the cost of obtaining forward solutions for each sampling parameter by utilising the weighted Reduced Basis method (RB) and the Empirical Interpolation Method (EIM). The proposed variant of a combined SQ-EIM-RB algorithm is based on an adaptive selection of training sets and a primal-dual, goal-oriented formulation for the EIM-RB approximation. Numerical examples show that the suggested computational framework can alleviate the computational costs associated with forward UQ for the pertinent large-scale models, thus providing a viable methodology for practical applications.

Model based techniques for automated condition monitoring of HVAC systems have been under development for some years. Results from the application of these methods to systems installed in real buildings have highlighted robustness and sensitivity issues. The generation of false alarms has been identified as a principal factor affecting the potential usefulness of condition monitoring in HVAC applications. The robustness issue is a direct result of the uncertain measurements and the lack of experimental control that axe characteristic of HVAC systems. This thesis investigates the uncertainties associated with implementing a condition monitoring scheme based on simple first principles models in HVAC subsystems installed in real buildings. The uncertainties present in typical HVAC control system measurements are evaluated. A sensor validation methodology is developed and applied to a cooling coil subsystem installed in a real building. The uncertainty in steady-state analysis based on transient data is investigated. The uncertainties in the simplifications and assumptions associated with the derivation of simple first principles based models of heat-exchangers are established. A subsystem model is developed and calibrated to the test system. The relationship between the uncertainties in the calibration data and the parameter estimates are investigated. The uncertainties from all sources are evaluated and used to generate a robust indication of the subsystem condition. The sensitivity and robustness of the scheme is analysed based on faults implemented in the test system during summer, winter and spring conditions.

Uncertainties are present in the inverse analysis of damage identification with respect to the given measurements, mainly the modelling uncertainties and the measurement uncertainties. Modelling uncertainties occur due to constructing a representative model of the real structure through finite element modelling, and representing damage in the real structures through changes in material parameters of the finite element model (assuming smeared crack approach). Measurement uncertainties are always present in the measurements despite the accuracy with which the measurements are measured or the precision of the instruments used for the measurement. The modelling errors in the finite element model are assumed to be encompassed in the updated uncertain parameters of the finite element model, given the uncertainties in the measurements and in the prior uncertainties of the parameters. The uncertainties in the direct measurement data are propagated to the estimated output data. Empirical models from codal provisions and standard recommendations are normally used for prediction of long-time deformations in concrete structures. Uncertainties are also present in the creep and shrinkage models, in the parameters of these models, in the shrinkage and creep mechanisms, in the environmental conditions, and in the in-situ measurements. All these uncertainties are needed to be considered in the damage identification and prediction of long-time deformations in concrete structures. In the context of modelling uncertainty, uncertainties can be categorized into aleatory or epistemic uncertainty. Aleatory uncertainty deals with the irresolvable indeterminacy about how the uncertain variable will evolve over time, whereas epistemic uncertainty deals with lack of knowledge. In the field of damage detection and prediction of long time deformations, aleatory uncertainty is modeled through probabilistic analysis, whereas epistemic uncertainty can be modeled through (1) Interval analysis (2) Ellipsoidal modeling (3) Fuzzy analysis (4) Dempster-Shafer evidence theory or (5) Imprecise probability. Many a times it is di cult to determine whether a particular uncertainty is to be considered as an aleatory or as an epistemic uncertainty, and the model builder makes the distinction. The model builder makes the choice based on the general state of scientific knowledge, on the practical need for limiting the model sophistication to a significant engineering importance, and on the errors associated with the measurements. Measurement uncertainty can be stated as the dispersion of real data resulting from systematic error (instrumental error, environmental error, observational error, human error, drift in measurement, measurement of wrong quantity) and random error (all errors apart from systematic errors). Most of instrumental errors given by the manufacturers are in terms of plus minus ranges and can be better represented through interval bounds. The vagueness involved in the representation of human error, observational error, and drift in measurement can be represented through interval bounds. Deliberate measurement of wrong quantity through cheaper and more convenient measurement units can lead to bad quality data. Quality of data can be better handled through interval analysis, with good quality data having narrow width of interval bounds and bad quality data having wide interval bounds. The environmental error, the electronic noise coming from transmitting the data and the random errors can be represented through probability distribution functions. A major part of the measurement uncertainties is better represented through interval bounds and the other part, is better represented through probability distributions. The uncertainties in the direct measurement data are propagated to the estimated output data (in damage identification techniques, the damaged parameters, and in the long-time deformation, the uncertain parameters of the deformation models, which are then used for the prediction of long-time deformations). Uncertainty based damage identification techniques and long-time deformations in concrete structures require further studies, when the measurement uncertainties are expressed through interval bounds only, or through both interval and probability using imprecise techniques. The thesis is divided into six chapters. Chapter 1 provides a review of existing literature on uncertainty based techniques for damage identification and prediction of long-time deformations in concrete structures. A brief review of uncertainty based methods for engineering applications is made, with special highlight to the need of interval analysis and imprecise probability for modeling uncertainties in the damage identification techniques. The review identifies that the available techniques for damage identification, where the uncertainties in the measurements and in the structural and material parameters are expressed in terms of interval bounds, lack e ciency, when the size of the damaged parameter vector is large. Studies on estimating the uncertainties in the damage parameters when the uncertainties in the measurements are expressed through imprecise probability analysis, are also identified as problems that will be considered in this thesis. Also the need for estimating the short-term time period, which in turn helps in accurate prediction of long-time deformations in concrete structures, along with a cost effective and easy to use system of measuring the existing prestress forces at various time instances in the short-time period is noted. The review identifies that most of modelers and analysts have been inclined to select a single simulation model for the long-time deformations resulted from creep, shrinkage and relaxation, rather than take all the possibilities into consideration, where the model selection is made based on the hardly realistic assumption that we can certainly select a correct, and the lack of confidence associated with model selection brings about the uncertainty that resides in a given model set. The need for a single best model out of all the available deformation models is needed to be developed, when uncertainties are present in the models, in the measurements and in the parameters of each models is also identified as a problem that will be considered in this thesis. In Chapter 2, an algorithm is proposed adapting the existing modified Metropolis Hastings algorithm for estimating the posterior probability of the damage indices as well as the posterior probability of the bounds of the interval parameters, when the measurements are given in terms of interval bounds. A damage index is defined for each element of the finite element model considering the parameters of each element are intervals. Methods are developed for evaluating response bounds in the finite element software ABAQUS, when the parameters of the finite element model are intervals. Illustrative examples include reinforced concrete beams with three damage scenarios mainly (i) loss of stiffness, (ii) loss of mass, and (iii) loss of bond between concrete and reinforcement steel, that have been tested in our laboratory. Comparison of the prediction from the proposed method with those obtained from Bayesian analysis and interval optimization technique show improved accuracy and computational efficiency, in addition to better representation of measurement uncertainties through interval bounds. Imprecise probability based methods are developed in Chapter 3, for damage identifi cation using finite element model updating in concrete structures, when the uncertainties in the measurements and parameters are imprecisely defined. Bayesian analysis using Metropolis Hastings algorithm for parameter estimation is generalized to incorporate the imprecision present in the prior distribution, in the likelihood function, and in the measured responses. Three different cases are considered (i) imprecision is present in the prior distribution and in the measurements only, (ii) imprecision is present in the parameters of the finite element model and in the measurement only, and (iii) imprecision is present in the prior distribution, in the parameters of the finite element model, and in the measurements. Illustrative examples include reinforced concrete beams and prestressed concrete beams tested in our laboratory. In Chapter 4, a steel frame is designed to measure the existing prestressing force in the concrete beams and slabs when embedded inside the concrete members. The steel frame is designed to work on the principles of a vibrating wire strain gauge and is referred to as a vibrating beam strain gauge (VBSG). The existing strain in the VBSG is evaluated using both frequency data on the stretched member and static strain corresponding to a fixed static load, measured using electrical strain gauges. The crack reopening load method is used to compute the existing prestressing force in the concrete members and is then compared with the existing prestressing force obtained from the VBSG at that section. Digital image correlation based surface deformation and change in neutral axis monitored by putting electrical strain gauges across the cross section, are used to compute the crack reopening load accurately. Long-time deformations in concrete structures are estimated in Chapter 5, using short-time measurements of deformation responses when uncertainties are present in the measurements, in the deformation models and in the parameters of the deformation models. The short-time period is defined as the least time up to which if measurements are made available, the measurements will be enough for estimating the parameters of the deformation models in predicting the long time deformations. The short-time period is evaluated using stochastic simulations where all the parameters of the deformation models are defined as random variables. The existing deformation models are empirical in nature and are developed based on an arbitrary selection of experimental data sets among all the available data sets, and each model contains some information about the deformation patterns in concrete structures. Uncertainty based model averaging is performed for obtaining the single best model for predicting the long-time deformation in concrete structures. Three types of uncertainty models are considered namely, probability models, interval models and imprecise probability models. Illustrative examples consider experiments in the Northwestern University database available in the literature and prestressed concrete beams and slabs cast in our laboratory for prediction of long-time prestress losses. A summary of contributions made in this thesis, together with a few suggestions for future research, are presented in Chapter 6. Finally the references that were studies are listed.