This study intended to examine Swedish upper secondary school students' argumentation related to the socioscientific issues about sustainable consumption and production, where the students take a position more specifically about a vegetarian diet. Examining sustainable development as an SSI becomes natural here as it is a constantly emerging feature in both the media but also within the school where it is used to give students a developing knowledge to be able to make informed decisions for future problems. This gave the idea to sustainable consumption and production which is one of the sub-goals (goal 12) of the UN goals for sustainable development which can be linked to the question of whether expanding vegetarian diets in schools would be better for sustainable development. In order to understand students' informal argumentation, the choice is to use the SEE-SEP model, which was used as a tool that gives the possibility to categorize arguments and gain an understanding of which grounds the arguments were based upon. The study will also examine the students' development of arguments during the course of the study to examine if there are changes to the argumentations during the study. The results show that students chose to mainly use environment/ecology and science-based arguments during the course of the study. An overview of the arguments shows that the students choose to use the knowledge aspect as their main support when it comes to the design of the arguments. The process of the study shows that there are changes in the design of the arguments and which categories are chosen to build the arguments.

This study investigated the relationship between hydrological, and to some extent, meteorological droughts, and meteorological variables and catchment characteristics in 235 Swedish catchments between 1983 and 2013. This was done in order to investigate what factors affect the drought sensitivity in Swedish catchments and to map the occurrence of droughts in Sweden between 1983 and 2013. There have been studies about which meteorological phenomena and catchment characteristics that promote hydrological droughts, but for Sweden this is relatively unexplored. To investigate droughts during the study period three indices were used: the Standardized Precipitation Index (SPI), which is an index for meteorological droughts, the Standardized Streamflow Index (SSI), which predicts hydrological droughts and a threshold index for streamflow droughts. These indices were used to identify the number of drought events and the total number of drought days. For the majority of the 235 Swedish catchments there were no significant trends for the number of drought events or the total number of drought days during the 30-year period. The SPI and the SSI were found to correlate best in time when adding a one-month lag period to the SSI time series. The correlations between the indices and the meteorological variables and the catchments properties varied depending on how the catchments were grouped according to latitude or elevation. For example, the number of drought events was positively correlated to the mean elevation of the catchments in north and central Sweden when using the SSI while there were no significant correlations with elevation in southern Sweden. Another example is that it was almost only in northern Sweden where significant correlations between the percentage of bedrock and drought characteristics were identified. The percentage of bedrock can be used as an indication for how much groundwater a catchment can store. The correlations also look different for the different indices. For example, when looking at all catchments together the number of drought events identified with the SPI was negatively correlated to latitude and mean elevation while the number of drought events identified with the SSI was positively correlated to the same variables. For further research into this topic it would be wise to study winter and summer droughts separately to better identify which are the driving variables. / I den här studien undersöktes sambanden mellan hydrologiska, och till viss del meteorologiska, torrperioder och bakomliggande meteorologiska drivvariabler och avrinningsområdesegenskaper i 235 svenska avrinningsområden mellan 1983 och 2013. Detta gjordes i syfte att undersöka vilka faktorer som påverkar känsligheten för torka i svenska avrinningsområden och för att kartlägga förekomsten av torrperioder i Sverige mellan 1983 och 2013. Internationellt finns det studier på vilka meteorologiska fenomen och egenskaper hos avrinningsområden som leder till risk för fler torrperioder, men för Sverige är det ett relativt outforskat område. För att undersöka torrperioder under den aktuella perioden användes tre index: Standardized Precipitation Index (SPI), vilket är ett index för meteorologiska torrperioder, Standardized Streamflow Index (SSI), som används för hydrologiska torrperioder och ett tröskelvärdes-index för att identifiera hydrologisk torka. Indexen användes för att identifiera antalet torrperioder och totala antalet dagar med torka under studieperioden. För majoriteten av de 235 avrinningsområdena gick det inte att se några signifikanta trender för antalet torrperioder eller totala antalet dagar med torka under perioden 1983-2013. SPI och SSI korrelerade bäst med varandra över tiden när SSI-tidsserien försköts med en månad. Korrelationerna mellan torrperioderna identifierade med de olika indexen och de meteorologiska variablerna och avrinningsområdesegenskaperna varierade beroende på hur avrinningsområdena grupperades efter latitud eller medelhöjd. Till exempel, i norra och centrala Sverige korrelerade antalet torrperioder för SSI positivt med medelhöjden medan det i södra Sverige inte fanns några signifikanta korrelationer. Ett annat exempel är att det nästan bara var i norra Sverige som det fanns korrelationer mellan procenten berggrund och de identifierade torrperiodsegenskaperna. Procenten berggrund i jordlagret kan användas som en indikation på hur mycket grundvatten som kan lagars i ett avrinningsområde. Korrelationerna skiljde sig också åt för de olika indexen. Till exempel, sett över alla avrinningsområden så var antalet torrperioder beräknat med SPI negativt korrelerade med latitud och medelhöjd medan antalet torrperioder beräknat med SSI var positivt korrelerade med dessa egenskaper. För vidare forskning inom detta område rekommenderas att titta separat på vinter- och sommartorkor för att bättre kunna identifiera potentiella drivvariabler.

In this thesis, the influence of soil-structure interaction (SSI) of end-frame bridges for high-speed railways was studied. Impedance functions, representing the SSI, was calculated and analyzed. The impedance functions were applied to end-frame bridge models which were analyzed for use in HSR. A new high-speed railway link is currently being planned in Sweden by the Swedish Transport Administration (Trafikverket). \textit{Ostl\"{a}nken} is planned to run between the cities of Stockholm and Link\"{o}ping with a maximum speed limit of 320km/h. As high-speed traffic induces high dynamic impact on bridges, dynamic analysis to ensure safety and passenger comfort is needed according to Eurocode. Thus, there is a demand of dynamically safe bridges that are also cost-effective. One cost-effective bridge is the soil integrated end-frame bridge, however, there are no design advice in Eurocode today on how to take SSI into consideration. The aim of the thesis has therefore been to investigate if the influence of SSI on end-frame bridges for HSR. This thesis was executed using the frequency domain approach to solve dynamic problems in finite element software. Furthermore, impedance functions have been obtained representing the SSI. Impedance functions take dynamic stiffness and dynamic damping into consideration where the damping consists of two parts: material damping and radiation damping due to energy dissipation in the form of elastic waves. To limit the model size, an absorbing region (AR) was used to mitigate waves originating from the source. The accuracy of impedance functions is dependent on several parameters and demands a great computational capacity to reach, mostly governed by the radiation condition. A parameter study of impedance functions was conducted, including parameters such as geometry, modulus of soil and detail levels. The impedance functions were then attached to bridge models on which trains modelled as moving point loads were applied. Envelopes of the acceleration and displacements have been presented and analyzed. Shear strain checks were made in order to verify the assumption of linear-elastic material behavior of the embankment. By using SSI in form of impedance functions attached to bridge models, numerical results show a great reduction of vibrations in models. The study suggests that a large end-frame, either long or high or both, may reduce acceleration as well as displacements. A stiffer embankment material may further reduce vibrations. Shear strain checks confirm that the assumption of linear-elastic soil behavior was true. / I det här exjobbet har påverkan av jord-struktur interaktion (soil-structure interaction - SSI) av ändskärmsbroar för höghastighetsbana blivit studerat. Impedansfunktioner som representerar SSI har beräknats och analyserats. Impdansfunktionerna har sedan applicerats på bromodeller och analyserats för höghastighetstrafik. Sveriges första höghastighetsbana håller just nu på att planeras av Trafikverket. Ostlänken kommer att bli den första delen och är planerad att gå från Stockholm till Linköping med en högsta hastighet av 320 km/h. Då höghastighetstrafik introducerar stor dynamisk på verkan på broar behövs dynamisk analys genomföras enligt Eurocode för att kunna säkerställa broarnas säkerhet och komfortkrav. Därför finns idag ett behov av dynamiskt säkra broar som också är kostnadseffektiva. En typ av kostnadseffektiv bro är den med jord integrerade ändskärmsbron. I dagens Eurocode finns dock inga konstruktionsråd vad gäller jord-struktur interaktion av ändskärmarna. Målet med detta examensarbete har därför varit att undersöka påverkan av SSI och besluta huruvida användandet av ändskärmsbron på höghastighetsbanor är legitimerat, eller om den ska undvikas. Det här examensarbetet har utgått från att lösa dynamiska problem i frekvensdomänen med hjälp av FEM. Impedansfunktioner som representerar jord-struktur interaktionen har tagits fram. Impedansfunktioner tar dels hänsyn till dynamisk styvhet och dels dynamisk dämpning. Den dynamiska dämpningen består av två delar; den första är materialdämpning och den andra är vågdämpning där energi dissiperar i vågform. För att begränsa FE modellens storlek har en absorbing region tillämpats för att absorbera vågorna vid randen. Impedansfunktionernas konvergens beror på flertalet parametrar och kräver en hög datakapacitet för att fås, mestadels beroende av radiatorvillkoret. En parameterstudie utfördes för att kunna analysera sensitiviteten hos impedansfunktionerna. Vidare applicerades dessa impedansfunktioner på skal- och balk-bromodeller på vilka HSLM laster påfördes. Skjuvtöjningskontroller gjordes för att verifiera att antagandet om linjärelastiskt materialbeteende var korrekt. Genom att ta hänsyn till SSI i form av impedansfunktioner tyder numeriska resultat på att vibrationer kan reduceras i hög grad. Envelopper visar att en stor ändskärm, antingen lång, hög eller bådadera, kan reducera accelerationer liksom förskjutningar. En styvare bank kan ytterligare reducera vibrationer.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Background Caesarean section deliveries are the most common procedures performed by obstetricians in Zimbabwe. Surgical site infections (SSI) following caesarean section delivery result in increased hospital stay, treatment, cost, hospital readmission rates and related maternal morbidity and mortality. There is no national surveillance system for SSIs in Zimbabwe, however, information is available on number of cases of post-operative wound infection after caesarean section, but the denominator and definition used is not consistent. The objective of this study were develop and strengthen the surveillance system in Zimbabwe, to establish a clinical-based system in a setting with limited microbiological access, to measure post-operative SSI after caesarean section and to describe the associated risk factors and to determine whether feedback of SSI data has any effect on the surgical site infection incidence rate. Methodology This was a before and after study with two rolling cohort periods conducted at two Central hospitals in Harare, Zimbabwe. An Infection Prevention and Control (IPC) intervention was conducted in-between. During the pre-intervention period, baseline demographic and clinical data were collected using a structured questionnaire, and during the post-intervention period the impact of the interventions was measured. Convenience sampling was employed. Results A total of 290 women consented to participate in the study in the pre intervention period, 86.9% (n= 252) completed the 30-days post-operative follow-up and the incidence rate of SSI was 29.0% (n=73, 95% CI:23.4-35.0) Interventions developed included: training in Infection Prevention and Control for health workers; implementation of a protocol for cleaning surgical instruments; dissemination of information on post-operative wound management for the women. After implementation of the intervention, 314 women were recruited for the post-intervention, 92.3%(n= 290) completed the 30-day follow-up and there was a significant (p<0.001) reduction in the incidence rate of SSIs to 12.1 % (n=35, 95% CI: 8.3 -15.8) during this period. Development of SSI after caesarean section was found to be significantly associated with emergency surgery (p<0.001), surgical wound class IV (p=0.001) and shaving at home (p<0.001) at both pre- intervention and post-intervention periods. Stellenbosch University https://scholar.sun.ac.za iii Conclusion This study shows that caesarean section can be performed with low incidence of SSI if appropriate interventions such as training in IPC, adequate cleaning of equipment and education in wound-care for the mother are adhered to. It also demonstrated a simple surveillance data collection tool can be used on a wide scale in resource limited countries to assist policy makers with monitoring and evaluation of SSI rates as well as assessment of risk factors. / AFRIKAANSE OPSOMMING: Agtergrond Keisersnitte is die mees algemene prosedure wat uitgevoer word deur obstetriese dokters in Zimbabwe. Chirurgiese wond infeksies wat op keisersnitte volg lei tot verlengde hospitaal verblyf, behandeling, koste, heropname koerse en verwante moederlike morbiditeit en mortaliteit. Alhoewel daar geen nasionale waaktoesig sisteem vir chirurgiese wondinfeksies is nie, is informasie beskikbaar vir ‘n aantal gevalle wat post-operatiewe wondinfeksie na ‘n keisersnit onwikkel het, maar die noemer en definisie word inkonsekwent gebruik. Die doel van hierdie studie was om die waaktoesig sisteem in Zimbabwe te ontwikkel en te versterk, om ‘n klinies-gebasseerde sisteem te vestig in ‘n opset met beprekte mikrobiologiese toegang, om postoperatiewe chirurgiese wond infeksies na keisersnitte te meet en om die geassosieerde risikofaktore te beskryf en om vas te stel of terugvoering van chirurgiese wondinfeksie data enige effek op die infeksiekoerse na keisersnitverlossings gehad het. Metodologie Hierdie was ‘n voor-en-na studie met twee kohort periodes uitgevoer by twee sentrale hospitale in Harare, Zimbabwe. ‘n Infeksievoorkoming en –beheer intervensie was tussenin uitgevoer. Tydens die pre-intervensie periode was basislyn demografiese en kliniese data ingesamel deur middel van ‘n gestruktureerde vraeboog, en gedurende die post-intervensie fase was die impak van die intervensies gemeet. Gerieflikheidsteekproefneming was geimplementeer. Resultate ‘n Totaal van 290 vroue het toestemming verleen om aan die studie deel te neem in die pre-intervensie periode, waarvan 86.9% (n=252) die 30 day post-operatiewe opvolg voltooi het en die insidensiekoers van chirurgiese wondinfeksies was 29.0% (n=73, 95% CI:23.4-35.0) Intervensies wat onwikkel was het ingesluit: opleiding in Infeksie Voorkoming en -Beheer vir gesondheidswerkers; die implementering van ‘n protokol om chirurgiese instrumente skoon te maak; disseminering van informasie oor post-operatiewe wondhantering vir vroue. Na die implimentering van die intervensie was 314 vroue gewerf in die post-intervensie fase, waarvan 92.3% (n=290) die 30 dae opvolg voltooi het. Daar was ‘n beduidende (p<0.001) verlaging in die insidensiekoers van chirurgiese wondinfeksies na 12.1% (n=35, 95% CI: 8.3-15.8) gedurende hierdie periode. Stellenbosch University https://scholar.sun.ac.za v Daar was bevind dat chirurgiese wondinfeksies beduidend geassosieer was met noodchirurgie (p<0.001), chirurgiese wondklassifikasie IV (p=0.001) en skeer van hare by die huis (p<0.001) by beide die pre-intervensie en post-intervensie periodes. Gevolgtrekking Hierdie studie wys dat keisersnitte uitgevoer kan word met ‘n lae insidensie van chirurgiese wondinfeksies indien toepaslike intervensies, soos opleiding in infeksievoorkoming en beheer, voldoende skoonmaak van toerusting en opvoeding in wondsorg vir die moeders. Dit het ook aangedui dat ‘n eenvoudige data-insameling instrument op ‘n wye basis gebruik kan word in beperkte-hulpbron lande om beleidmakers te help met monitering en evaluering van chirurgiese wondinfeksie koerse, asook die assessering van risikofaktore.

La sécurité des systèmes d’information s’inscrit dans la dépendance croissante des entreprises envers leur SI en perspective du nombre grandissant d’incidents de sécurité. Dans cette recherche, nous nous intéressons à la gestion des risques SI, pour laquelle la littérature souligne le manque d’implication des top-managers. Nous abordons cette problématique sous l’angle de la décision des dirigeants, au travers de quatre approches théoriques : modèles des perceptions managériales des risques SI, perception des risques en psychologie, théorie néo-institutionnelle et théorie sur l’adoption symbolique des innovations. L’objectif est de rendre intelligible les influences sur l’adoption symbolique de la SSI. Nous employons une méthode qualitative organisée autour de 17 études de cas dans des entreprises d’activités variées. La SSI y est observée comme un processus de décision de gestion des risques SI. Nos résultats montrent la pertinence d’étudier la SSI selon une perspective individuelle de gestion des risques. D’une part, les caractéristiques de l’évaluation psychologique des risques éclairent les biais pour la gestion du risque SI. D’autre part, l’étude de ces biais apporte une perspective nouvelle sur la compréhension de l’investissement des top-managers pour la SSI. Nous montrons l’insensibilité des top-managers à l’exposition du risque, une préférence à aborder les risques sous l’angle des menaces. Aussi, nous exposons les influences qui contribuent à adopter une SSI technique et non managériale pourtant suggérée dans la littérature. Enfin, notre analyse fait émerger des perspectives pour prolonger la compréhension d’une SSI réactive, décriée par les auteurs en SSI. / The information system security for which the interest joins in the increasing dependence of companies to them information system and in prospect of increasing number of security incidents. We are interested in the information system risk management, for whom the literature underlines the lack of involvement of top-managers.We approach the concern under the view of the decision of top executives for ISS, through four theoretical streams: the models of the managerial perceptions of IS risks, the risks perception in psychology, the institutional theory and the theory about symbolic adoption of the innovations. The aim is to make intelligible the influences on the symbolic adoption of such ISS approach. We use a qualitative method organized around 17 case studies in companies with varied activities. Our results highlight the relevance to study the ISS according to an individual perspective of risk management. On one hand, the characteristics of the psychological evaluation of the risks enlighten the biases for the management of the information system risk. On the other hand, the study of these biases brings a new perspective on the understanding of the investment of the top executives for the ISS. In particular, we underline the insensitivity of the top managers in the exposure of the risk, a preference to approach the risks under a threats point of view. We expose the influences which contribute to adopt a technical and not managerial ISS such as suggests by the Research. Finally, our analysis brings to the foreground perspectives to extend the comprehension of a reactive ISS, defame by ISS’ academics.

Detecção de dano em estruturas de engenharia de grandes dimensões através da análise de suas características dinâmicas envolve diversos campos de estudo. O primeiro deles trata da identificação dos parâmetros modais da estrutura, uma vez que executar testes de vibração livre em tais estruturas não é uma tarefa simples, necessita-se de um método robusto que seja capaz de identificar os parâmetros modais dessa estrutura a ações ambientais, campo esse chamado de análise modal operacional. Este trabalho trata do problema de detecção de dano em estruturas que possam ser representadas através de modelos em pórticos planos e vigas e que estejam submetidos à ação de vibrações ambientais. A localização do dano é determinada através de um algoritmo de otimização conhecido como Backtracking Search Algorithm (BSA) fazendo uso de uma função objetivo que utiliza as frequências naturais e modos de vibração identificados da estrutura. Simulações e testes são feitos a fim de verificar a concordância da metodologia para ambos os casos. Para as simulações, são utilizados casos mais gerais de carregamentos dinâmicos, e dois níveis de ruído (3% e 5%) são adicionados ao sinal de respostas para que esses ensaios se assemelhem aos ensaios experimentais, onde o ruído é inerente do processo. Já nos ensaios experimentais, apenas testes de vibração livre são executados. Diversos cenários de dano são propostos para as estruturas analisadas a fim de se verificar a robustez da rotina de detecção de dano. Os resultados mostram que a etapa de identificação modal estocástica através do método de identificação estocástica de subespaço (SSI) teve ótimos resultados, possibilitando, assim, a localização da região danificada da estrutura em todos os casos analisados. / Damage detection in large dimensions engineering structures through the analysis of their dynamic characteristics involves several fields. The first one deals with the structure modal identification parameter, since running free vibration tests in such structures is not a simple task, robust methods are needed in order to identify the modal parameters of this structure under ambient vibrations, this field is known as operational modal analysis. This work deals with the problem of damage detection in structures under ambient vibrations that can be represented by FEM using frame and beam elements. The damage location is determined through an optimization algorithm know as Backtracking Search Algorithm (BSA). It uses as objective function the identified natural frequencies and modes of vibration of the structure. Numerical and experimental tests are performed to assess the agreement of the methodology for both cases. For the numerical tests, more general cases of dynamic loads are used, and two noise levels (3% and 5%) are added to the response signal to assessing the robustness of the methodology close to the field conditions, in which noise is inherent of the process. In the experimental tests, only free vibration tests are performed. Several damage scenarios are proposed for the analyzed structures to check the robustness of the damage detection routine. The results show that the stochastic modal identification using the stochastic subspace identification (SSI) method had excellent results, thus allowing the location of the damaged region of the structure in all analyzed cases.

Detecção de dano em estruturas de engenharia de grandes dimensões através da análise de suas características dinâmicas envolve diversos campos de estudo. O primeiro deles trata da identificação dos parâmetros modais da estrutura, uma vez que executar testes de vibração livre em tais estruturas não é uma tarefa simples, necessita-se de um método robusto que seja capaz de identificar os parâmetros modais dessa estrutura a ações ambientais, campo esse chamado de análise modal operacional. Este trabalho trata do problema de detecção de dano em estruturas que possam ser representadas através de modelos em pórticos planos e vigas e que estejam submetidos à ação de vibrações ambientais. A localização do dano é determinada através de um algoritmo de otimização conhecido como Backtracking Search Algorithm (BSA) fazendo uso de uma função objetivo que utiliza as frequências naturais e modos de vibração identificados da estrutura. Simulações e testes são feitos a fim de verificar a concordância da metodologia para ambos os casos. Para as simulações, são utilizados casos mais gerais de carregamentos dinâmicos, e dois níveis de ruído (3% e 5%) são adicionados ao sinal de respostas para que esses ensaios se assemelhem aos ensaios experimentais, onde o ruído é inerente do processo. Já nos ensaios experimentais, apenas testes de vibração livre são executados. Diversos cenários de dano são propostos para as estruturas analisadas a fim de se verificar a robustez da rotina de detecção de dano. Os resultados mostram que a etapa de identificação modal estocástica através do método de identificação estocástica de subespaço (SSI) teve ótimos resultados, possibilitando, assim, a localização da região danificada da estrutura em todos os casos analisados. / Damage detection in large dimensions engineering structures through the analysis of their dynamic characteristics involves several fields. The first one deals with the structure modal identification parameter, since running free vibration tests in such structures is not a simple task, robust methods are needed in order to identify the modal parameters of this structure under ambient vibrations, this field is known as operational modal analysis. This work deals with the problem of damage detection in structures under ambient vibrations that can be represented by FEM using frame and beam elements. The damage location is determined through an optimization algorithm know as Backtracking Search Algorithm (BSA). It uses as objective function the identified natural frequencies and modes of vibration of the structure. Numerical and experimental tests are performed to assess the agreement of the methodology for both cases. For the numerical tests, more general cases of dynamic loads are used, and two noise levels (3% and 5%) are added to the response signal to assessing the robustness of the methodology close to the field conditions, in which noise is inherent of the process. In the experimental tests, only free vibration tests are performed. Several damage scenarios are proposed for the analyzed structures to check the robustness of the damage detection routine. The results show that the stochastic modal identification using the stochastic subspace identification (SSI) method had excellent results, thus allowing the location of the damaged region of the structure in all analyzed cases.

No description available.

College student satisfaction is a concept that has become more prevalent in higher education research journals. Little attention has been given to the psychometric properties of previous instrumentation, and few studies have investigated the structure of current satisfaction instrumentation. This dissertation: (a) investigated the tenability of the theoretical dimensional structure of the Noel-Levitz Student Satisfaction Inventory™ (SSI), (b) investigated an alternative factor structure using explanatory factor analyses (EFA), and (c) used multiple-group CFA procedures to determine whether an alternative SSI factor structure would be invariant for three demographic variables: gender (men/women), race/ethnicity (Caucasian/Other), and undergraduate classification level (lower level/upper level). For this study, there was little evidence for the multidimensional structure of the SSI. A single factor, termed General Satisfaction with College, was the lone unidimensional construct that emerged from the iterative CFA and EFA procedures. A revised 20-item model was developed, and a series of multigroup CFAs were used to detect measurement invariance for three variables: student gender, race/ethnicity, and class level. No measurement invariance was noted for the revised 20-item model. Results for the invariance tests indicated equivalence across the comparison groups for (a) the number of factors, (b) the pattern of indicator-factor loadings, (c) the factor loadings, and (d) the item error variances. Because little attention has been given to the psychometric properties of the satisfaction instrumentation, it is recommended that further research continue on the SSI and any additional instrumentation developed to measure student satisfaction. It is possible that invariance issues may explain a portion of the inconsistent findings noted in the review of literature. Although measurement analyses are a time-consuming process, they are essential for understanding the psychometrics characterized by a set of scores obtained from a survey, or any other form of assessment instrument.

Detecção de dano em estruturas de engenharia de grandes dimensões através da análise de suas características dinâmicas envolve diversos campos de estudo. O primeiro deles trata da identificação dos parâmetros modais da estrutura, uma vez que executar testes de vibração livre em tais estruturas não é uma tarefa simples, necessita-se de um método robusto que seja capaz de identificar os parâmetros modais dessa estrutura a ações ambientais, campo esse chamado de análise modal operacional. Este trabalho trata do problema de detecção de dano em estruturas que possam ser representadas através de modelos em pórticos planos e vigas e que estejam submetidos à ação de vibrações ambientais. A localização do dano é determinada através de um algoritmo de otimização conhecido como Backtracking Search Algorithm (BSA) fazendo uso de uma função objetivo que utiliza as frequências naturais e modos de vibração identificados da estrutura. Simulações e testes são feitos a fim de verificar a concordância da metodologia para ambos os casos. Para as simulações, são utilizados casos mais gerais de carregamentos dinâmicos, e dois níveis de ruído (3% e 5%) são adicionados ao sinal de respostas para que esses ensaios se assemelhem aos ensaios experimentais, onde o ruído é inerente do processo. Já nos ensaios experimentais, apenas testes de vibração livre são executados. Diversos cenários de dano são propostos para as estruturas analisadas a fim de se verificar a robustez da rotina de detecção de dano. Os resultados mostram que a etapa de identificação modal estocástica através do método de identificação estocástica de subespaço (SSI) teve ótimos resultados, possibilitando, assim, a localização da região danificada da estrutura em todos os casos analisados. / Damage detection in large dimensions engineering structures through the analysis of their dynamic characteristics involves several fields. The first one deals with the structure modal identification parameter, since running free vibration tests in such structures is not a simple task, robust methods are needed in order to identify the modal parameters of this structure under ambient vibrations, this field is known as operational modal analysis. This work deals with the problem of damage detection in structures under ambient vibrations that can be represented by FEM using frame and beam elements. The damage location is determined through an optimization algorithm know as Backtracking Search Algorithm (BSA). It uses as objective function the identified natural frequencies and modes of vibration of the structure. Numerical and experimental tests are performed to assess the agreement of the methodology for both cases. For the numerical tests, more general cases of dynamic loads are used, and two noise levels (3% and 5%) are added to the response signal to assessing the robustness of the methodology close to the field conditions, in which noise is inherent of the process. In the experimental tests, only free vibration tests are performed. Several damage scenarios are proposed for the analyzed structures to check the robustness of the damage detection routine. The results show that the stochastic modal identification using the stochastic subspace identification (SSI) method had excellent results, thus allowing the location of the damaged region of the structure in all analyzed cases.