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.

In the last 35 years, several researchers have proposed, developed and tested different friction devices for seismic control of structures. Their research has demonstrated that such devices are simple, economical, practical, durable and very effective. However, research on passive friction dampers, except for few instances, has not been given appropriate attention lately. This has caused some of the results of old studies to become out-of-date, lose their validity in the context of today's design philosophies or to fall short on the expectations of this century's structural engineering. An analytical study on the behavior of friction devices and the effect they have on the structures into which they are incorporated has been undertaken to address the new design trends, codes, evaluation criteria and needs of today's society. The present study consists of around 7,000 structural analyses that are used to show the excellent seismic performance and economic advantages of Friction Damped Braced Frames. It serves, at the same time, to improve our understanding on their dynamic behavior. Finally, this thesis also sets the basis for future research on the application of this type of seismic energy dissipating systems.

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.

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.

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.