Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 124-127. / by Enrique J. Laya. / M.S.

"This dissertation proposes a vibration-based approach to detect and monitor structural damage by tracking the instantaneous modal parameters. A change in the instantaneous modal parameters indicates change in the structural health condition. In contrast to many existing structural health monitoring schemes, the proposed approach is less model dependent and works well for both sudden and evolving damage, general loading conditions and complex structures. The instantaneous modal parameters, including modal frequency, mode shape vector and modal damping ratio, are introduced as a bridge between the system properties and time varying vibration modes. The theoretical background of the time-varying vibration modes is developed. It has been shown that for slowly time-varying systems such modes exist and the instantaneous modal parameters have a clear physical interpretation and can be identified from free and forced vibration responses. A set of known techniques are used in an innovative way to identify the instantaneous modal parameters. Applicability of the identification techniques depends on the nature and availability of measurement data. Wavelet ridge method is used to identify the instantaneous modal frequencies and normalized instantaneous mode shape vectors from free vibration data. Wavelet packet sifting technique in conjunction with Hilbert transform and confidence index is proposed to identify the normalized instantaneous mode shape vector from both free and forced vibration data. Time-varying Kalman filter is integrated with the wavelet packet sifting technique to identify the instantaneous modal frequencies and the instantaneous modal damping ratios from free and forced vibration data. The proposed approach has been validated using both simulation and experimental data. The simulation data is obtained from a multi-degree-of-freedom system with time varying stiffness under different loading conditions. Experimental data include both impact testing data from the ASCE benchmark study and shaking-table test data of a full-size two-story wooden building structure, conducted at DPRI, Kyoto University, Japan. It has been shown that the proposed approach can successfully detect and monitor damage and, therefore, has great potential for real applications."

Abstract not available

Aging bridges in the United States demand effective, efficient, and economical strengthening techniques to meet future traffic requirements. One such technique is to bond steel or fiber reinforced polymer (FRP) plates to the tension faces of reinforced concrete bridge beams with adhesives to strengthen them in flexure. However, beams that have been flexurally strengthened in this manner often fail prematurely, in particular by plate end peeling. The benefits of flexural strengthening by externally bonded reinforcement can only be fully realized by preventing premature failure modes so as to allow the development of composite action between the beam and the external reinforcement. With this goal in mind, several critical limit states of externally reinforced beams are examined in this thesis. Models developed by Roberts (1989) and by Colotti, Spadea, and Swamy (2004) that predict premature plate end debonding are examined in depth using data from previously conducted experimental programs that employed both steel and FRP external reinforcement. In addition, various parameters of the concrete beam, adhesive, and external reinforcement are analyzed in each model to determine the role of each parameter in failure prediction. A critical appraisal of the performance of the models using existing experimental data leads to the selection of the Roberts (1989) model. This model is used to develop recommended design guidelines for flexurally strengthening reinforced concrete bridge beams with externally bonded FRP plates and for preventing premature plate peeling.

Procurando conhecer o grau de deterioração precoce das estruturas de concreto armado dos edifícios residenciais da Região Metropolitana da Cidade do Recife, Estado de Pernambuco, este trabalho visa, utilizando um método de quantificação dos danos e o uso de ensaios, avaliar as patologias das estruturas estudadas. Estudou-se três edifícios residenciais (ER), com semelhante padrão de construção, idades construtivas aproximadas e inseridos em diferentes classes de agressividade ambiental. Foi realizada inspeção visual e ensaios em amostras dos pilares, vigas, lajes e reservatório inferior do subsolo dos três edifícios. Após análise dos três edifícios, verificou-se que o caso ER 1, localizado em classe ambiental de agressividade forte (III), a mais agredida pelo meio ambiente, e o estudo de caso ER 2, localizado a uma distância significativa da orla marinha em Classe de Agressividade Ambiental II, apresentaram grau de deterioração media (GD) de 36,98 e 31,23 respectivamente, com recomendação para inspeção periódica e intervenção a médio prazo. Já o estudo de caso ER 3, que está localizado dentro da uma classe de agressividade forte (III), em orla marinha, porém com barreiras de proteção que evitam a incidência direta da névoa salina, encontra-se com alto grau de deterioração (GD = 103,94), sugerindo uma intervenção imediata com riscos de colapso / This work aims to evaluate the pathology of residential buildings structures located at the Metropolitan Region of Recife, Brazil using the quantification of damages to measure the degree of early deterioration of reinforced concrete. Three residential buildings (RB) with similar construction standards were studied. All buildings have approximate age and are inserted into environmental aggressiveness distinct. A visual inspection took place as well as a laboratorial sample analysis of their pillars, beams and underground water reservatories. It was verified that the RB1 case, located at a high environmental aggressiveness class (III), and the RB2 case, located significatively far from the sea and classified with a moderate environmental aggressiveness class (II), both presented a medium degree of deterioration (GDE). For both buildings it is suggested a periodic inspection recommendation and a medium term intervention (GD 1 = 36,98 ; GD 2 = 31,23). The third case (RB3), located at a high environmental aggressiveness class (III) and seafront with protection barriers, presented a high degree of deterioration (GD 3=103,94). It is suggested for RB3 an immediate intervention with collapse risks

Nos últimos 20 anos, alguns municípios da Região Metropolitana do Recife - PE, têm sido afetados por problemas diversos em obras de Engenharia Civil, contabilizando, inclusive, óbitos. O mais grave desses problemas, dado ao número de edificações envolvidas, diz respeito aos prédios tipo caixão; alguns ruíram e vários foram e estão interditados e houve desinterdição. O objetivo geral da presente dissertação é analisar os laudos técnicos produzidos sobre os prédios tipo caixão, construídos nos Municípios de Olinda, Jaboatão dos Guararapes e Paulista - PE, tendo como meta estudar as causas apontadas para os desabamentos e interdições das referidas edificações. De um modo geral, pode-se apontar como causas dos desabamentos, as seguintes: falhas ou insuficiência de projeto (31,4%); baixa qualidade ou inadequação dos materiais (17,1%); falhas ou vícios de construção (34,4%); causas ambientais (17,1%). Já para as interdições: falhas ou insuficiência de projeto (21,4%); baixa qualidade ou inadequação dos materiais (3,5%); falhas ou vícios de construção (2,8%); uso inadequado ou falta de manutenção (26,0%); causas ambientais (4,3%); outras causas (42,0%). As desinterdições ocorreram quando foram atendidas as restrições feitas pela Defesa Civil de cada município, e que envolviam problemas estruturais e de habitabilidade. Constata-se também uma atuação inadequada dos órgãos de fiscalização e a ausência de padronização dos laudos e de um modelo técnico para a recuperação adequada dessas construções. Espera-se ter contribuído, através da análise e sistematização dos dados contidos nos laudos estudados, para trabalhos futuros, visando o desenvolvimento de tecnologia capaz de equacionar a situação dos referidos imóveis / In the past 20 years, some cities of the Metropolitan Area of Recife - PE, have been affected by several problems in Civil Engineering constructions, some of which resulted in human deaths. The most serious of these problems, given the number of constructions involved, concerns the specific building called box; some of the buildings did fall and several others have been interdicted. Just a few of them were cleared and the majority of them continue to be interdicted. The general objective of the present dissertation is to analyze the awards produced on the building type box, built in the cities of Olinda, Jaboatão dos Guararapes and Paulista. Its goal is to study the causes pointed out as responsible for the collapse and interdictions of those constructions. In a general way, it can be pointed out as causes of the collapses, the following ones: imperfections or insufficiency of project (31.4%); low quality or inadequacies of the materials (17.1%); construction mistakes (34.4%); environmental causes (17.1%). For the interdictions: imperfections or insufficiencies of project (21.4%); low quality or inadequacies of the materials (3.5%); construction mistakes (2.8%); inadequate use or lack of maintenance (26.0%); environmental causes (4.3%); other causes (42.0%). The buildings were cleared when the conditions made by the Civil Defense of each city were met; they involved structural problems and habitability. Its also evident an inadequate performance of the inspection agencies and the lack of standardization of the awards, as well as the absence of a model for the adequate recovery of these constructions. One expects to have contributed, through the analysis and systematization of the data contained in the studied awards, for future works, aiming at the development of technology capable to equate the situation of the cited real estates.

Made available in DSpace on 2017-06-01T17:57:23Z (GMT). No. of bitstreams: 1 Mauro Melo_Dissert.pdf: 1426265 bytes, checksum: 0a54c25d1117b83eb91a5131e2fc6841 (MD5) Previous issue date: 2007-10-17 / In the past 20 years, some cities of the Metropolitan Area of Recife - PE, have been affected by several problems in Civil Engineering constructions, some of which resulted in human deaths. The most serious of these problems, given the number of constructions involved, concerns the specific building called box ; some of the buildings did fall and several others have been interdicted. Just a few of them were cleared and the majority of them continue to be interdicted. The general objective of the present dissertation is to analyze the awards produced on the building type box , built in the cities of Olinda, Jaboatão dos Guararapes and Paulista. Its goal is to study the causes pointed out as responsible for the collapse and interdictions of those constructions. In a general way, it can be pointed out as causes of the collapses, the following ones: imperfections or insufficiency of project (31.4%); low quality or inadequacies of the materials (17.1%); construction mistakes (34.4%); environmental causes (17.1%). For the interdictions: imperfections or insufficiencies of project (21.4%); low quality or inadequacies of the materials (3.5%); construction mistakes (2.8%); inadequate use or lack of maintenance (26.0%); environmental causes (4.3%); other causes (42.0%). The buildings were cleared when the conditions made by the Civil Defense of each city were met; they involved structural problems and habitability. It s also evident an inadequate performance of the inspection agencies and the lack of standardization of the awards, as well as the absence of a model for the adequate recovery of these constructions. One expects to have contributed, through the analysis and systematization of the data contained in the studied awards, for future works, aiming at the development of technology capable to equate the situation of the cited real estates. / Nos últimos 20 anos, alguns municípios da Região Metropolitana do Recife - PE, têm sido afetados por problemas diversos em obras de Engenharia Civil, contabilizando, inclusive, óbitos. O mais grave desses problemas, dado ao número de edificações envolvidas, diz respeito aos prédios tipo caixão ; alguns ruíram e vários foram e estão interditados e houve desinterdição. O objetivo geral da presente dissertação é analisar os laudos técnicos produzidos sobre os prédios tipo caixão , construídos nos Municípios de Olinda, Jaboatão dos Guararapes e Paulista - PE, tendo como meta estudar as causas apontadas para os desabamentos e interdições das referidas edificações. De um modo geral, pode-se apontar como causas dos desabamentos, as seguintes: falhas ou insuficiência de projeto (31,4%); baixa qualidade ou inadequação dos materiais (17,1%); falhas ou vícios de construção (34,4%); causas ambientais (17,1%). Já para as interdições: falhas ou insuficiência de projeto (21,4%); baixa qualidade ou inadequação dos materiais (3,5%); falhas ou vícios de construção (2,8%); uso inadequado ou falta de manutenção (26,0%); causas ambientais (4,3%); outras causas (42,0%). As desinterdições ocorreram quando foram atendidas as restrições feitas pela Defesa Civil de cada município, e que envolviam problemas estruturais e de habitabilidade. Constata-se também uma atuação inadequada dos órgãos de fiscalização e a ausência de padronização dos laudos e de um modelo técnico para a recuperação adequada dessas construções. Espera-se ter contribuído, através da análise e sistematização dos dados contidos nos laudos estudados, para trabalhos futuros, visando o desenvolvimento de tecnologia capaz de equacionar a situação dos referidos imóveis

Made available in DSpace on 2017-06-01T17:57:27Z (GMT). No. of bitstreams: 1 pre-textual.pdf: 28868 bytes, checksum: 1349eefd05bbc7c21b1dd3b9e4b92ecb (MD5) Previous issue date: 2006-04-20 / This work aims to evaluate the pathology of residential buildings structures located at the Metropolitan Region of Recife, Brazil using the quantification of damages to measure the degree of early deterioration of reinforced concrete. Three residential buildings (RB) with similar construction standards were studied. All buildings have approximate age and are inserted into environmental aggressiveness distinct. A visual inspection took place as well as a laboratorial sample analysis of their pillars, beams and underground water reservatories. It was verified that the RB1 case, located at a high environmental aggressiveness class (III), and the RB2 case, located significatively far from the sea and classified with a moderate environmental aggressiveness class (II), both presented a medium degree of deterioration (GDE). For both buildings it is suggested a periodic inspection recommendation and a medium term intervention (GD 1 = 36,98 ; GD 2 = 31,23). The third case (RB3), located at a high environmental aggressiveness class (III) and seafront with protection barriers, presented a high degree of deterioration (GD 3=103,94). It is suggested for RB3 an immediate intervention with collapse risks / Procurando conhecer o grau de deterioração precoce das estruturas de concreto armado dos edifícios residenciais da Região Metropolitana da Cidade do Recife, Estado de Pernambuco, este trabalho visa, utilizando um método de quantificação dos danos e o uso de ensaios, avaliar as patologias das estruturas estudadas. Estudou-se três edifícios residenciais (ER), com semelhante padrão de construção, idades construtivas aproximadas e inseridos em diferentes classes de agressividade ambiental. Foi realizada inspeção visual e ensaios em amostras dos pilares, vigas, lajes e reservatório inferior do subsolo dos três edifícios. Após análise dos três edifícios, verificou-se que o caso ER 1, localizado em classe ambiental de agressividade forte (III), a mais agredida pelo meio ambiente, e o estudo de caso ER 2, localizado a uma distância significativa da orla marinha em Classe de Agressividade Ambiental II, apresentaram grau de deterioração media (GD) de 36,98 e 31,23 respectivamente, com recomendação para inspeção periódica e intervenção a médio prazo. Já o estudo de caso ER 3, que está localizado dentro da uma classe de agressividade forte (III), em orla marinha, porém com barreiras de proteção que evitam a incidência direta da névoa salina, encontra-se com alto grau de deterioração (GD = 103,94), sugerindo uma intervenção imediata com riscos de colapso

Made available in DSpace on 2017-06-01T17:57:28Z (GMT). No. of bitstreams: 1 benigno.pdf: 3630982 bytes, checksum: 145549a81097148696e4a7118a0508af (MD5) Previous issue date: 2006-07-25 / The products and services of architecture and engineering need to assist with quality, the expectations and needs of who hire them. This research project proposes the accomplishment of an inventory of the city of Recife consumers' most frequent complaints to Consumer Defense Consultantship ADC, that works inside of the Regional Council of Engineering, Architecture and Agronomy of the State of Pernambuco CREA - PE, and starting from them to identify causes and reasons that made their occurrence. The data will also be researched along with the builders, through the reports of final evaluation of their constructions. It will also be studied some tragedies in the civil construction where these structures collapsed. By the analysis of them, we look for subsidies for the prevention and/or remediation of the detected problems. Besides, it is expected that starting from this diagnosis it will be possible to trace guidelines for continuous education in the most several levels / Os produtos e serviços de arquitetura e engenharia precisam atender com qualidade as expectativas e necessidades de quem os contratam. Esta dissertação apresenta um levantamento das queixas mais freqüentes dos consumidores da cidade do Recife e Região Metropolitana a Assessoria de Defesa do Consumidor - ADC, que funciona dentro Conselho Regional de Engenharia, Arquitetura e Agronomia do Estado de Pernambuco CREA - PE, sobre os defeitos encontrados decorrentes dos erros cometidos no processo da indústria da construção civil, e a partir deles diagnosticar as suas causas e as razões que levaram à sua ocorrência. Busca-se com a análise dos mesmos, subsídios para indicar a prevenção e/ou remediação dos problemas detectados. Espera-se que a partir deste diagnóstico seja possível, inclusive, sugerir a instalação de uma educação continuada nos mais diversos níveis do ensino da engenharia

Throughout recent history, famous records of building failures may be found, unfortunately accompanied by great human loss and major economic consequences. One of the mechanisms of failure is referred to as ‘progressive collapse’: one or several structural members suddenly fail, whatever the cause (accident or attack). The building then collapses progressively, every load redistribution causing the failure of other structural elements, until the complete failure of the building or of a major part of it. The civil engineering community’s attention to this type of event was first drawn by the progressive collapse of the building called Ronan Point, following a gas explosion in one of the last floors. Different simplified procedures for simulating the effects of progressive collapse can now be found in the literature, some of them described in detail. However, no extensive study can be found, in which these procedures are compared to more complete approaches for progressive collapse simulation, aiming at the comparison of the assumptions underlying them. To further contribute to the elaboration of design codes for progressive collapse, such a study would therefore be of great interest for practitioners.<p>All parties involved with the subject of progressive collapse are currently attempting to bridge the gap between the work done on the research front on the one hand, what can be considered as a fitting numerical model for regular industrial use on the other, and finally, the normalisation committees. The present research work aims at providing insight as to how the gaps between these poles may be reduced. The approach consists in studying the various hypotheses one by one, and gradually adding complexities to the numerical model, if they prove to be warranted by the need for sufficient accuracy. One of the contributions of the present work stems from this approach, in that it provides insight regarding the validity of the various simplifying assumptions. It also leads to the development of procedures which are kept as simple as possible, in an attempt to design them as best as possible for regular industrial use.<p>The objective of simplifying assumptions validation is pursued in Chapter 2. This chapter consists of the text of a paper entitled “Comparison and study of different progressive collapse simulation techniques for RC structures”, in which the main simplifying assumptions of the progressive collapse guidelines are detailed and assessed. The DoD [1] and GSA [2] static linear and non-linear procedures are investigated, and compared to more complete approaches in order to assess their validity.<p>In the next two chapters, two new procedures for design against progressive collapse are developed. They are based on quasi-static computations, their main objective being to account accurately for dynamic inertial effects. The first of these chapters consists in the text of a paper entitled “A new pushover analysis procedure for structural progressive collapse based on a kinetic energy criterion”, in which energetic considerations allow for the development of a static equivalent pushover procedure. The second chapter consists of the text of a paper entitled “A new pushover analysis procedure for structural progressive collapse based on optimised load amplification factors”, which uses load amplification factors resulting from optimisation procedures in order to account for dynamic inertial effects. The contributions of these two papers lie in the fact that they offer an improved accuracy on the results, when compared with other procedure available in the literature, which follow the same general principles. The two proposed procedures are thoroughly validated by systematic comparisons with results obtained with the more costly dynamic non-linear computations.<p>Finally, an additional chapter focuses on the various approaches that can be adopted for the simulation of reinforced concrete beams and columns. Because a rather simple model for reinforced concrete is used in Chapter 2, the bulk of this chapter consists in the implementation of a more complex fibre-based non-linear beam element. Comparisons performed with this model provide insight to the limitations of the simpler model, which is based on the use of lumped plastic hinges, but show this simpler model to be valid for the purposes of the present work.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished