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Changes in the characteristics of the structure, such as damage, have not been considered in most of the active and semi-active control methods that have been used to control and optimize the response of civil engineering structures. In this dissertation, a direct adaptive control which can deal with the existence of measurement errors and changes in structural characteristics or load conditioning is used to control the performance of structures. A Simple Adaptive Control Method (SACM) is modified to control civil structures and improve their performance. The effectiveness of the SACM is verified by several numerical examples. The SACM is used to reduce the structural response such as drift and acceleration using active and semi-active devices, and its performance is compared with that of other control methods. Also, a probabilistic indirect adaptive control method is developed and its behavior is compared to the SACM using a simple numerical example. In addition to the simplicity of the SACM implementation, the results show that SACM is very effective to reduce the response of structures with linear and non-linear behavior in comparison with other control methods.

Vibrations caused by rough road excitations influence tracked vehicle dynamic performance. Good capabilities of such vehicles like high mobility, manoeuvrability and comfort are guaranteed by optimal suspension systems. The suspension systems of tracked vehicles are exposed to extreme operating conditions. This creates a conflict between ride comfort and handling that is even greater than the conflict between ride comfort and handling for general road vehicles. Tracked vehicles must be able to traverse not only rough roads but also smooth terrains. The challenges in developing an optimized suspension system for tracked vehicles include the high and changeable damping forces required for tracked vehicles crossing rough terrains. The use of active or semi-active suspension systems overcomes the limitations inherent in the conventional passive suspension. However, active suspension systems are expensive, complicated to design and have high power demand. Thus, semi-active suspension systems have emerged as a good compromise between active and passive suspension system. There is considerable current research on the applications of magnetorheological (MR) fluid dampers for semi-active suspensions of executive brand of some cars. However, there is very little research on semi-active devices for tracked vehicle suspension. In fact, currently, there is no commercially available large scale MR dampers in the market that produce the high damping force to suit such applications. In response to these requirements, this research proposes a novel semi-active tracked vehicle suspension system that uses MR dampers to improve the ride comfort and handling characteristics of tracked vehicles. It also assesses the dynamics of the new suspension with various semi-active control methods. This study is conducted in four phases. The first phase provides a numerical investigation on the dynamic performance of a seven-degrees-of-freedom (7-DOF) passive suspension model of the armour personnel carrier (APC) M113 tracked vehicle. The numerical investigation considers the influence of variation of five suspension design parameters on the vehicle dynamic performance. These parameters include number, locations of hydraulic shock absorber, damping coefficient, suspension and wheel stiffnesses. The results indicate that the optimal suspension performance is attained by using two or three dampers. The best locations for these dampers are at the extreme road wheels i.e. the first, second and last road wheel stations. Moreover, the vehicle performance is reduced when the damping coefficient is increased. Additionally, low suspension stiffness offers better vehicle ride while high wheel stiffness degrades the vehicle performance. These results identify the limitations inherent in the conventional passive suspension. For the second phase, the dynamic characteristics of the hydraulic, hydro-gas and MR dampers are experimentally measured and fitted using the Chebyshev orthogonal functions to produce the restoring force surfaces for each damper, which are compared. On one hand, the restoring force surfaces of the hydraulic and hydro-gas dampers show fixed properties at specified frequencies. On the other hand, the restoring force surfaces of the MR dampers show properties that can be controlled at the same specified frequencies by the variation of the applied current levels. Thus, the potential and the effectiveness of the controllable properties of MR dampers for semi-active vibration control is demonstrated. Also, in this phase, the best set of parameters to use in the modified Bouc-Wen model to characterise the MR dampers, has been derived. The third phase of the project is also experimentally based. A new and novel test rig which represents the 7-DOF scaled suspension model of the tracked vehicle is designed and fabricated. The primary purpose of the test rig is to evaluate the performance of the proposed suspension with MR dampers. Furthermore, experiments are conducted on the test rig to evaluate some semi-active control methods and their effectiveness in reducing suspension vibration. The results show that the use of two or three MR dampers at the extreme wheels offers optimal suspension performance. This confirms the numerical results that are derived from the full scale passive suspension system with hydraulic dampers. The experimental results also show that skyhook control and hybrid control (which combines groundhook and skyhook controls) of the semi-active suspension are more effective in reducing the road-induced vibration and improving the suspension dynamic behaviours. Also, validations of the predicted responses of the semi-active scaled MR suspension model with the measured responses have been presented. The fourth and final phase provides a numerical simulation on the development and evaluation of the semi-active control methods for a full scale tracked vehicle suspension with MR dampers using the validated suspension model. Three semi-active control strategies are proposed. The first two controllers are the skyhook and hybrid controls which provide better suspension performance. In addition, the third controller, which is an intelligent fuzzy-hybrid control system, is used to optimize the suspension performance. The results from this intelligent system are compared with the two traditional control methods (skyhook and hybrid controls) under bump, sinusoidal and random excitations. It is shown that the proposed controller can enhance simultaneously the vehicle ride and handling characteristics.

The main focus of this study is on the active and semi-active control of civil engineering structures subjected to seismic excitations. Among different candidate control strategies, the sliding mode control approach emerges as a convenient alternative, because of its superb robustness under parametric and input uncertainties. The analytical developments and numerical results presented in this dissertation are directed to investigate the feasibility of application of the sliding mode control approach to civil structures. In the first part of this study, a unified treatment of active and semi-active sliding mode controllers for civil structures is presented. A systematic procedure, based on a special state transformation, is also presented to obtain the regular form of the state equations which facilitates the design of the control system. The conditions under which this can be achieved in the general case of control redundancy are also defined. The importance of the regular form resides in the fact that it allows to separate the design process in two basic steps: (a) selection of a target sliding surface and (b) determination of the corresponding control actions. Several controllers are proposed and extensive numerical results are presented to investigate the performance of both active and semi-active schemes, examining in particular the feasibility of application to real size civil structures. These numerical studies show that the selection of the sliding surface constitutes a crucial step in the implementation of an efficient control design. To improve this design process, a generalized sliding surface definition is used which is based on the incorporation of two auxiliary dynamical systems. Numerical simulations show that this definition renders a controller design which is more flexible, facilitating its tuning to meet different performance specifications. This study also considers the situation in which not all the state information is available for control purposes. In practical situations, only a subset of the physical variables, such as displacements and velocities, can be directly measured. A general approach is formulated to eliminate the explicit effect of the unmeasured states on the design of the sliding surface and the associated controller. This approach, based on a modified regular form transformation, permits the utilization of arbitrary combinations of measured and unmeasured states. The resulting sliding surface design problem is discussed within the framework of the classical optimal output feedback theory, and an efficient algorithm is proposed to solve the corresponding matrix nonlinear equations. A continuous active controller is proposed based only on bounding values of the unmeasured states and the input ground motion. Both active and semi-active schemes are evaluated by numerical simulations, which show the applicability and performance of the proposed approach. / Ph. D.

The main purpose of this research is to investigate the effectiveness and feasibility of semi-active control systems for structural protection during severe earthquake loading. However, the research reported herein also involves analytical studies on the effect of adding viscous damping to the second and fourth quadrants of the force-displacement curve, and laboratory and field testing of a fibre-optic gyroscope (FOG) for measuring rotations in civil engineering structures. The concept of the 2-4 viscous damping is introduced to reduce the response of single-degree-of-freedom (SDOF) systems subjected to harmonic and earthquake excitations. This concept involves the addition of structural viscous damping to the second and fourth quadrants of the force-displacement graph. Time-history analyses and response spectra for various SDOF systems are carried out to assess the effect of adding 2-4 viscous damping. The analytical results indicate that the addition of 2-4 viscous damping is beneficial for reducing the harmonic and seismic response of a wide range of SDOF systems. A newly developed semi-active resettable device is proposed to reduce the seismic response of a one-fifth scale structure. The device is investigated as part of a resettable tendon system installed in the structure. Nonlinear dynamic analyses are performed to determine the optimal configuration of the resettable tendon in the structure. Several shake table tests are performed on the structure equipped with two resettable devices. The dynamic characteristics of the structure and the devices are described. Various earthquake records at different levels of intensity are used during the seismic testing. Different control laws are employed to manipulate the hysteretic behaviour of the devices. The results of the shake table tests validate the effectiveness of the resettable devices to reduce the seismic response of structures. Analytical studies are performed to determine the optimal utilization of the resettable devices in a twelve-storey reinforced concrete building. The seismic performance of the structure is discussed in relation to the number and distribution of the devices. Inelastic time-history analyses are carried out to assess the effectiveness of the devices to reduce the seismic response of the building. The impact of various tendon arrangements and different control laws on the earthquake response is investigated. Relevant issues for the implementation of the resettable devices in actual building systems are identified. Finally, a new measurement concept based on the use of the fibre-optic gyroscope is proposed to measure rotation rates, rotations, displacements and inter-storey drifts of civil engineering structures. FOGs are compact, easy to install and, unlike conventional linear potentiometers, do not require a fixed reference frame to operate. Measurements recorded during the seismic testing of the one-fifth scale structure and displacement measurements at the Sky Tower in Auckland validate the suitability of the FOGs for applications in civil engineering.

This thesis explores next generation passive and semi-active tuned mass damper (PTMD and SATMD) building systems for reducing the seismic response of tall structures and mitigating damage. The proposed structural configuration separates the upper storey(s) of a structure to act as the 'tuned' mass, either passively or semi-actively. In the view point of traditional TMD system theory, this alternative approach avoids adding excessive redundant mass that is rarely used. In particular, it is proposed to replace the passive spring damper system with a semi-active resetable device based system (SATMD). This semi-active approach uses feedback control to alter or manipulate the reaction forces, effectively re-tuning the system depending on the structural response. In this trade-off parametric study, the efficacy of spreading stiffness between resetable devices and rubber bearings is illustrated. Spectral analysis of simplified 2-DOF model explores the efficacy of these modified structural control systems and the general validity of the optimal derived parameters is demonstrated. The end result of the spectral analysis is an optimally-based initial design approach that fits into accepted design methods. Realistic suites of earthquake ground motion records, representing seismic excitations of specific return period probability, are utilised, with lognormal statistical analysis used to represent the response distribution. This probabilistic approach avoids bias toward any particular type of ground motion or frequency content. Statistical analysis of the performance over these suites thus better indicates the true overall efficacy of the PTMD and SATMD building systems considered. Several cases of the segregated multi-storey TMD building structures utilising passive devices (PTMD) and semi-active resetable devices (SATMD) are described and analysed. The SATMD building systems show significant promise for applications of structural control, particularly for cases where extra storeys might be added during retrofit, redevelopment or upgrade. The SATMD approach offers advantages over PTMD building systems in the consistent response reductions seen over a broad range of structural natural frequencies. Using an array of performance metrics the overall structural performance is examined without the typically narrow focus found in other studies. Performance comparisons are based on statistically calculated storey/structural hysteretic energy and storey/structural damage demands, as well as conventional structural response performance indices. Overall, this research presents a methodology for designing SATMD building systems, highlighting the adaptable structural configuration and the performance obtained. Thus, there is good potential for SATMD building systems, especially in retrofit where lack of space constrains some future urban development to expand upward. Finally, the approach presented offers an insight into how rethinking typical solutions with new technology can offer dramatic improvements that might not otherwise be expected or obtainable.

Orientador: Gustavo Luiz Chagas Manhães de Abreu / Resumo: Fluidos magnetoreológicos (MR) são fluidos capazes de alterar suas propriedadesreológicas quando um campo magnético é aplicado sobre ele. Uma das aplicações maisimportantes do fluido MR é em amortecedores de vibrações, utilizados principalmente naconstrução civil, veículos automotivos e outros sistemas mecânicos sujeitos a excitaçõesque provocam vibrações indesejáveis. Na indústria automobilística, atualmente atecnologia dos amortecedores que utilizam fluido MR vem se destacando como umasolução que pode trazer benefícios de conforto e segurança aos usuários de veículos emgeral. Este trabalho discute a modelagem não-linear de um veículo que considera adinâmica vertical, lateral e longitudinal, simulado em diferentes condições de conduçãoque buscam avaliar o conforto, a aderência à estrada, a dirigibilidade, a rolagem e adeflexão da suspensão. Pretende, também, contribuir com a área de controle de vibraçõesem suspensões veiculares que utilizam amortecedores MR, avaliando o desempenho doscontroladores ótimo (LQR), nebuloso e FEB (Frequency-Estimation-Based ) projetadosem 1/4 de veículo e aplicados ao modelo não-linear do veículo. O trabalho terminacomentando as potencialidades da metodologia apresentada, discutindo as facilidadese dificuldades encontradas na sua implementação e aponta propostas para a suacontinuidade. / Doutor

Submitted by THIAGO GALBIATI LAGOIN null (thiagolagoin@yahoo.com.br) on 2017-10-26T18:00:51Z No. of bitstreams: 1 lagoin_tg_dr_ilha.pdf: 10803891 bytes, checksum: 11fc5487a11d931ddaa2432fe578288e (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-10-31T18:40:57Z (GMT) No. of bitstreams: 1 lagoin_tg_dr_ilha.pdf: 10803891 bytes, checksum: 11fc5487a11d931ddaa2432fe578288e (MD5) / Made available in DSpace on 2017-10-31T18:40:57Z (GMT). No. of bitstreams: 1 lagoin_tg_dr_ilha.pdf: 10803891 bytes, checksum: 11fc5487a11d931ddaa2432fe578288e (MD5) Previous issue date: 2017-09-28 / Fluidos magnetoreológicos (MR) são fluidos capazes de alterar suas propriedades reológicas quando um campo magnético é aplicado sobre ele. Uma das aplicações mais importantes do fluido MR é em amortecedores de vibrações, utilizados principalmente na construção civil, veículos automotivos e outros sistemas mecânicos sujeitos a excitações que provocam vibrações indesejáveis. Na indústria automobilística, atualmente a tecnologia dos amortecedores que utilizam fluido MR vem se destacando como uma solução que pode trazer benefícios de conforto e segurança aos usuários de veículos em geral. Este trabalho discute a modelagem não-linear de um veículo que considera a dinâmica vertical, lateral e longitudinal, simulado em diferentes condições de condução que buscam avaliar o conforto, a aderência à estrada, a dirigibilidade, a rolagem e a deflexão da suspensão. Pretende, também, contribuir com a área de controle de vibrações em suspensões veiculares que utilizam amortecedores MR, avaliando o desempenho dos controladores ótimo (LQR), nebuloso e FEB (Frequency-Estimation-Based ) projetados em 1/4 de veículo e aplicados ao modelo não-linear do veículo. O trabalho termina comentando as potencialidades da metodologia apresentada, discutindo as facilidades e dificuldades encontradas na sua implementação e aponta propostas para a sua continuidade. / Magnetorheological fluids (MR) are capable of changing their rheological properties when a magnetic field is applied. One of the most important applications of the MR fluid is in vibration dampers, mainly used in construction, automobiles and other mechanical systems subjected to excitations that cause unwanted vibrations. In the automotive industry, nowadays the technology of dampers using MR fluid has emerged as a solution which can bring benefits of comfort and safety to overall vehicle users. This work discusses the non-linear modeling of a vehicle which considers the vertical, lateral and longitudinal dynamics, simulated in different driving conditions aiming evaluate the comfort, the road holding, the handling, the roll and the suspension deflection. It also aims to contribute to the field of vibration control in vehicular suspensions that use magnetoreological dampers, evaluating the performance of controllers optimal (LQR), fuzzy and FEB (Frequency-Estimation-Based ) designed in 1/4 of vehicle and applied to the non-linear model of the vehicle. This work is concluded presenting the potentialities of the design methodology proposed and future developments to be implemented.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17883号 / 工博第3792号 / 新制||工||1580(附属図書館) / 30703 / 京都大学大学院工学研究科建築学専攻 / (主査)教授 中島 正愛, 教授 川瀬 博, 教授 竹脇 出 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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