The active control of structures is a diverse field of study, with new applications being developed continually. One structural system, which is often not considered a dynamic system, is the floor of a building. In many cases the dynamics of a floor system are neglected in the design phase of a building structure. Occasionally, this omission results in a floor which has dynamic characteristics found to be unacceptable for the intended use of the building. Floor motion of very small amplitudes, often caused by pedestrian movement, is sometimes found objectionable by occupants of the building space. Improving an unacceptable floor system's dynamic characteristics after construction can be disruptive, difficult and costly. In search of alternative repair measures, analytical and experimental research implementing active control techniques was conducted to improve the vibration characteristics of problem floors. Specifically, a control scheme was developed utilizing the measured movement of the floor to compute the input signal to an electromagnetic actuator which, by the movement of the actuator reaction mass, supplies a force that reduces the transient and resonant vibration levels. Included in the analytical component of this research is the development of a mathematical model for a full scale experimental test floor. This model is studied, using a matrix computation software, to evaluate the effectiveness of the control scheme. The experimental component of the research serves two purposes. The first is the verification of the system behavior assumed in the analytical component of the research. The second is the verification of control system effectiveness for various excitations, control gains, and actuator locations on the experimental test floor and six additional floors. / Ph. D.

With the increased deterioration of infrastructure in this country, it has become important to find ways to maintain the strength and integrity of a structure over its design life. Being able to control the amount a structure displaces or vibrates during a seismic event, as well as being able to model this nonlinear behavior, provides a new challenge for structural engineers. This research proposes a wavelet-based adaptive neuro- fuzzy inference system for use in system identification and structural control of civil engineering structures. This algorithm combines aspects of fuzzy logic theory, neural networks, and wavelet transforms to create a new system that effectively reduces the number of sensors needed in a structure to capture its seismic response and the amount of computation time needed to model its nonlinear behavior. The algorithm has been tested for structural control using a three-story building equipped with a magnetorheological damper for system identification, an eight-story building, and a benchmark highway bridge. Each of these examples has been tested using a variety of earthquakes, including the El-Centro, Kobe, Hachinohe, Northridge, and other seismic events.

Graduation date: 1996

The objective of this thesis is to describe the design, construction, implementation and performance of a prototype adaptive pendulum tuned mass damper (APTMD). Furthermore the thesis aims at demonstrating the performance improvements obtained when the tuned mass damper (TMD) parameters are optimized. The study considers the effect of adjusting the APTMD tuned frequency and damping ratio on a two storey test structure subjected to broadband and narrowband excitation. An analytical model of the APTMD for a single-degree-of-freedom (SDOF) structure is used to demonstrate the performance improvements when the APTMD parameters are optimized. The optimized model considers the effects of adjusting the frequency ratio, damping ratio, and mass ratio of the combined system to reduce the maximum deflection when the structure is subjected to a harmonic excitation force. The analytical model is used to simulate the optimal performance of the APTMD system. The experimental APTMD is capable of identifying the structural vibration modes in real time and tuning to the desired mode. The structural vibration modes are identified by calculating the windowed power spectral density of the structure’s acceleration, followed by peak-picking algorithm to identify the modal frequencies. Tuning is performed by moving the pivot location of the pendulum arm via a tuning frame along a set of rails. The design also allows for changes in the external dampening force. An adjustable damper is attached to the pendulum mass to allow for control of the APTMD damping ratio. A prototype of the APTMD is built and tested in a modal testing setup. The test structure is a two-storey model of a building structure. The structure is excited using a shaker fixed to the lower storey of the structure. The performance of the APTMD under broadband and narrowband excitation is examined for various tuning and damping parameters. The performance of the APTMD system under optimally tuned and detuned conditions is investigated. The results of the experimental studies demonstrate the importance of optimizing the TMD tuned frequency and damping ratio to reduce structural vibrations. Since the APTMD is designed to autonomously update both parameters, it is an effective tool in mitigating structural vibrations where user interaction is either difficult or expensive. Further study on the performance of a prototype APTMD applied to a large scale structure is required before implementation on full-scale structures.

Surfactant-templated, sol-gel based methodologies for the synthesis of tailored, nanostructured, hybrid inorganic–organic materials are incredibly powerful and versatile. Although growth in this field has been explosive in recent decades, a lot of room remains to contribute to the design and synthesis of new materials, as well as the development of advanced applications. In the work described herein, we firstly explored the synthesis of thick, mesoporous organosilica films and their application as functional coatings for solution-based, fibre-optic heavy metal sensors. Notably, sub-ppm level detection was observed for the detection of Pb(II) in mixed aqueous–organic media in short timeframes, and progress has been made toward synthesizing organotitania films that would allow for heavy metal sensing in purely aqueous solution. Furthermore, the utility of these types of surfactant-templated, organically-functionalized, mesostructured coatings has been preliminarily extended to other types of optical devices for heavy metal sensing. We have also explored the use of designer amphiphilic, alkyl oligosiloxane precursors for the tightly-controlled formation of thin, self-templated, hybrid nanostructured films. Moreover, films bearing uniaxial 2D hexagonal alignment over macroscopic length scales were obtained using polymer-treated substrates to control the interfacial interactions between the film precursors and the substrate surface. In addition, a relatively mild UV / ozone treatment was employed to remove the alkyl moieties from the films to yield porous materials without catastrophic loss of the as-synthesized, mesostructural order. Lastly, novel chiral, binaphthylene-based, periodic mesoporous organosilica (PMO) materials have been prepared. With the aim of demonstrating chiral recognition with such materials, porous, co-continuous capillary monoliths have been synthesized and applied as chiral stationary phases in nano-HPLC and CEC. Notably, enantioselective interactions between our materials and a chiral acetal-based analyte have been observed. Quantification of these enantioselective interactions in chiral PMOs by isothermal titration microcalorimetry is also being pursued. It has thus been demonstrated that a wide array of different functional materials may be accessed through template-based synthetic strategies. By varying parameters such the starting monomers, the sol composition, and the interfacial interactions between reacting species and a given substrate (to name a few), the resulting materials may be tailored to meet the demands of new and emerging technologies. / Thesis (Ph.D, Chemistry) -- Queen's University, 2011-05-24 19:50:17.478

This thesis explores the creation and assessment of semi-active control algorithms for both squat shear buildings and tall flexible structures. If cost-effective, practicable, semi-active structural control systems can be developed, the potential reduction in loss of both property and lives due to seismic events is significant. Semi-active controllers offer many of the benefits of active systems, but have power requirements orders of magnitude smaller, and do not introduce energy to the structural system. Previous research into semi-active controllers has shown their potential in linear simulations with single earthquake excitations. The distinguishing feature of this investigation is the use of appropriate non-linear modelling techniques and realistic suites of seismic excitations in the statistical assessment of the semi-active control systems developed. Finite element time-history analysis techniques are used in the performance assessment of the control algorithms developed for three and nine story structural models. The models include non-linear effects due to structural plasticity, yielding, hysteretic behaviour, and P-delta effects. Realistic suites of earthquake records, representing seismic excitations with specific return period probability, are utilised, with lognormal statistical analysis used to represent the response distribution. In addition to displacement focused control laws, acceleration and jerk regulation control methods are developed, showing that potential damage reduction benefits can be obtained from these new control approaches. A statistical assessment of control architecture is developed and undertaken, examining the distribution of constant maximum actuator authority for both squat shear buildings, and tall slender structures, highlighting the need to consider non-linear structural response characteristics when implementing semi-active control systems. Finally, statistical analysis of all results and normalised values shows the efficacy of each control law and actuator type relative to different magnitude seismic events. As a result, this research clearly presents, for the first time, explicit tradeoffs between control law, architecture type, non-linear structural effects, and seismic input characteristics for the semi-active control of civil structures.

The objective of this thesis is to describe the design, construction, implementation and performance of a prototype adaptive pendulum tuned mass damper (APTMD). Furthermore the thesis aims at demonstrating the performance improvements obtained when the tuned mass damper (TMD) parameters are optimized. The study considers the effect of adjusting the APTMD tuned frequency and damping ratio on a two storey test structure subjected to broadband and narrowband excitation. An analytical model of the APTMD for a single-degree-of-freedom (SDOF) structure is used to demonstrate the performance improvements when the APTMD parameters are optimized. The optimized model considers the effects of adjusting the frequency ratio, damping ratio, and mass ratio of the combined system to reduce the maximum deflection when the structure is subjected to a harmonic excitation force. The analytical model is used to simulate the optimal performance of the APTMD system. The experimental APTMD is capable of identifying the structural vibration modes in real time and tuning to the desired mode. The structural vibration modes are identified by calculating the windowed power spectral density of the structure’s acceleration, followed by peak-picking algorithm to identify the modal frequencies. Tuning is performed by moving the pivot location of the pendulum arm via a tuning frame along a set of rails. The design also allows for changes in the external dampening force. An adjustable damper is attached to the pendulum mass to allow for control of the APTMD damping ratio. A prototype of the APTMD is built and tested in a modal testing setup. The test structure is a two-storey model of a building structure. The structure is excited using a shaker fixed to the lower storey of the structure. The performance of the APTMD under broadband and narrowband excitation is examined for various tuning and damping parameters. The performance of the APTMD system under optimally tuned and detuned conditions is investigated. The results of the experimental studies demonstrate the importance of optimizing the TMD tuned frequency and damping ratio to reduce structural vibrations. Since the APTMD is designed to autonomously update both parameters, it is an effective tool in mitigating structural vibrations where user interaction is either difficult or expensive. Further study on the performance of a prototype APTMD applied to a large scale structure is required before implementation on full-scale structures.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 224-227).

Esta dissertação analisa a estrutura do controle da concentração empresarial prevista na Lei de Defesa da Concorrência brasileira e realizada pelo Sistema Brasileiro de Defesa da Concorrência (SBDC) a partir da perspectiva do consumidor. Considera a legislação atualmente em vigor e verifica sobretudo a atuação do Conselho Administrativo de Defesa Econômica (CADE). Verifica o protocolo de apreciação da concentração pela Administração Pública, destacando a interpretação conferida ao artigo 54, § 3º da Lei 8.884/1994 e a sua efetividade. Analisa as formas de mensurar os benefícios decorrentes dos atos de concentração empresarial e de garantir que esses benefícios sejam distribuídos equitativamente entre os seus participantes e os consumidores ou usuários finais, como determina a Lei de Defesa da Concorrência. Os três capítulos que formam a presente dissertação apresentam as características das concentrações de empresas e do seu controle e analisam os principais modelos que têm pautado a atuação administrativa neste tema. Os resultados obtidos demonstram que crescem diuturnamente os atos de concentração de empresas apresentados ao CADE e que há um modelo específico de análise de eficiências, já utilizado pela autarquia, que demonstra de forma mais fidedigna a efetividade do requisito da distribuição equitativa dos benefícios decorrentes da concentração econômica entre os seus participantes e os consumidores ou usuários finais. / This work analyzes the structure of merger control under the Brazilian Antitrust Law as performed by the Brazilian Competition Defense System from the consumer perspective. It considers the currently legislation and checks the work of the Administrative Council for Economic Defense and checks the protocol of assessment of the merger by the Administration, highlighting the interpretation given to the article 54, § 3º of the Law 8.884/1994 and its effectiveness. The text looks at possible ways to measure the benefits of mergers and to ensure that these benefits are distributed equitably among its participants and consumers or final users, as required by the Antitrust Law. The three chapters that make up this work present the characteristics of merger and of their control and analyze the main models that have guided the administrative action in this regard. The results show that there is currently a growth of merger submitted to the Administrative Council for Economic Defense and that there is a specific model that analyses the efficiencies, already used by the Council, which shows more reliably the effectiveness of the requirement for equitable distribution of economic benefits arising from the merger between its participants and consumers or final users.

Esta dissertação analisa a estrutura do controle da concentração empresarial prevista na Lei de Defesa da Concorrência brasileira e realizada pelo Sistema Brasileiro de Defesa da Concorrência (SBDC) a partir da perspectiva do consumidor. Considera a legislação atualmente em vigor e verifica sobretudo a atuação do Conselho Administrativo de Defesa Econômica (CADE). Verifica o protocolo de apreciação da concentração pela Administração Pública, destacando a interpretação conferida ao artigo 54, § 3º da Lei 8.884/1994 e a sua efetividade. Analisa as formas de mensurar os benefícios decorrentes dos atos de concentração empresarial e de garantir que esses benefícios sejam distribuídos equitativamente entre os seus participantes e os consumidores ou usuários finais, como determina a Lei de Defesa da Concorrência. Os três capítulos que formam a presente dissertação apresentam as características das concentrações de empresas e do seu controle e analisam os principais modelos que têm pautado a atuação administrativa neste tema. Os resultados obtidos demonstram que crescem diuturnamente os atos de concentração de empresas apresentados ao CADE e que há um modelo específico de análise de eficiências, já utilizado pela autarquia, que demonstra de forma mais fidedigna a efetividade do requisito da distribuição equitativa dos benefícios decorrentes da concentração econômica entre os seus participantes e os consumidores ou usuários finais. / This work analyzes the structure of merger control under the Brazilian Antitrust Law as performed by the Brazilian Competition Defense System from the consumer perspective. It considers the currently legislation and checks the work of the Administrative Council for Economic Defense and checks the protocol of assessment of the merger by the Administration, highlighting the interpretation given to the article 54, § 3º of the Law 8.884/1994 and its effectiveness. The text looks at possible ways to measure the benefits of mergers and to ensure that these benefits are distributed equitably among its participants and consumers or final users, as required by the Antitrust Law. The three chapters that make up this work present the characteristics of merger and of their control and analyze the main models that have guided the administrative action in this regard. The results show that there is currently a growth of merger submitted to the Administrative Council for Economic Defense and that there is a specific model that analyses the efficiencies, already used by the Council, which shows more reliably the effectiveness of the requirement for equitable distribution of economic benefits arising from the merger between its participants and consumers or final users.