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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Assessing Cumulative Effects in Georgian Bay, Ontario Using a Food Web Structure as a Metric

Salt, Rachel 30 August 2013 (has links)
Cumulative effects, often minor individually but collectively significant, are continually being grappled with by researchers, policy makers and practitioners. Despite this the Canadian approach to cumulative effects assessment is thought by many to be ineffective. In this thesis I investigate the literature that surrounds cumulative effects and uncovered three distinct themes that occur chronologically: genesis, project-based approach and integration. During the genesis phase cumulative effects nomenclature, ideas and frameworks was created. The main theme of this era was to asses these effects at a large scale and to have a strong understanding of a systems ecology prior to the assessment. This approach was found to be too complex and so a more narrow project-based approach was implemented and still remains today. This approach is heavily criticized and as such researchers are now trying to find an approach that integrates these two divergent themes into a regional level assessment. I have found there to be several frameworks but an absence of effective regional methodologies. There is a need for regional metrics if this approach is to ever be institutionally supported. Food web structure can be evaluated at multiple scales and has been shown to be responsive to environmental variation; thus, it has potential for application as a metric for cumulative effects. Here, using stable isotope analysis, I field test integrative measures of food web structure (food chain length, habitat coupling, trophic omnivory) at sites of varying degrees of anthropogenic stressors in Georgian Bay, Ontario to evaluate the use of food webs as a metric for cumulative effects assessment. I found that food web structure varied significantly among sites. Sites with high levels of stress displayed structural characteristics reflective of human activities such as shorter food chain lengths, increased trophic omnivory, and reduced habitat coupling relative to the non-stressed sites. These results indicate that food web structure as an ecosystem level metric may provide insight into anthropogenic activities, and may be applied routinely as a metric for doing Cumulative Effects Assessment. / University of Guelph, Saugeen Ojibway Nation, Georgian Bay Forever
132

A Study in Preference Elicitation under Uncertainty

Hines, Greg January 2011 (has links)
In many areas of Artificial Intelligence (AI), we are interested in helping people make better decisions. This help can result in two advantages. First, computers can process large amounts of data and perform quick calculations, leading to better decisions. Second, if a user does not have to think about some decisions, they have more time to focus on other things they find important. Since users' preferences are private, in order to make intelligent decisions, we need to elicit an accurate model of the users' preferences for different outcomes. We are specifically interested in outcomes involving a degree of risk or uncertainty. A common goal in AI preference elicitation is minimizing regret, or loss of utility. We are often interested in minimax regret, or minimizing the worst-case regret. This thesis examines three important aspects of preference elicitation and minimax regret. First, the standard elicitation process in AI assumes users' preferences follow the axioms of Expected Utility Theory (EUT). However, there is strong evidence from psychology that people may systematically deviate from EUT. Cumulative prospect theory (CPT) is an alternative model to expected utility theory which has been shown empirically to better explain humans' decision-making in risky settings. We show that the standard elicitation process can be incompatible with CPT. We develop a new elicitation process that is compatible with both CPT and minimax regret. Second, since minimax regret focuses on the worst-case regret, minimax regret is often an overly cautious estimate of the actual regret. As a result, using minimax regret can often create an unnecessarily long elicitation process. We create a new measure of regret that can be a more accurate estimate of the actual regret. Our measurement of regret is especially well suited for eliciting preferences from multiple users. Finally, we examine issues of multiattribute preferences. Multiattribute preferences provide a natural way for people to reason about preferences. Unfortunately, in the worst-case, the complexity of a user's preferences grows exponentially with respect to the number of attributes. Several models have been proposed to help create compact representations of multiattribute preferences. We compare both the worst-case and average-case relative compactness.
133

Die Untersuchung der replikativen Seneszenz kaniner dermaler Fibroblasten als Beitrag zur Alternsforschung

Streit, Susanne 15 May 2006 (has links) (PDF)
Mit der vorliegenden Arbeit sollte nachgewiesen werden, dass bei in vitro kultivierten kaninen dermalen Fibroblasten einer Hunderasse nach einer bestimmte Kultivierungszeit replikative Seneszenz entsteht und dass das replikative Vermögen dieser Zellen in der Zellkultur abhängig vom Alter des Spendertieres ist. Dreißig Beagle aus zwei Versuchstieranstalten wurden als Hautspender genutzt. Diese Tiere wurden in die drei Altersgruppen jung, adult und alt unterteilt. Mit Hilfe einer Hautstanze wurde bei allen Tieren im Bereich der rechten Skapula ein Hautstück gewonnen. Diese Hautstücken wurden in Zellkulturflaschen verbracht. Die aus diesem Explantat auswandernden Zellen stellten die Grundlage für die Primärkultur dar. Die Zellen wurden in regelmäßigen Abständen subkultiviert. Dabei wurden immer die Gesamtzellzahl und die Vitalität der Kulturen bestimmt. Diese Werte bildeten die Grundlage für die Berechnung der Parameter des replikativen Vermögens der Zellen. Auf Grundlage der erstellten Wachstumskurven konnte die Generationszeit der Zellen berechnet werden. Parallel zur Kultivierung der Zellen erfolgte die morphologische Betrachtung der Zellen mit Hilfe eines Phasenkontrastmikroskops und histologischen Färbungen, die unter dem Lichtmikroskop näher beurteilt wurden. / This thesis aims to demonstrate that, after a certain period of time, replicative senescence develops in canine dermal fibroblasts of a certain dog breed when cultured in vitro. It is also shown that the replicative capacity of these cells is related to the age of the donor animal. Thirty Beagles from two experimental facilities were used as skin donors. The animals were divided in three age groups: young, adult and old. Skin samples from the right scapula were taken from all animals by means of a punch biopsy and transferred to cell culture vessels. The primary culture was based on the cells emigrating from these explants. The cells were subcultured at regular intervals, at which the total number of cells and the vitality of the cultures were also determined. Based on these parameters, the replicative capacity of the cells was calculated and growth curves were created, which were then used to calculate the generation times of the cells. Parallel to cultivation, the cells underwent morphological dissection using a phase contrast microscope on the one hand and a light-optical microscope with histological staining on the other hand.
134

Estimation of the parameters of stochastic differential equations

Jeisman, Joseph Ian January 2006 (has links)
Stochastic di®erential equations (SDEs) are central to much of modern finance theory and have been widely used to model the behaviour of key variables such as the instantaneous short-term interest rate, asset prices, asset returns and their volatility. The explanatory and/or predictive power of these models depends crucially on the particularisation of the model SDE(s) to real data through the choice of values for their parameters. In econometrics, optimal parameter estimates are generally considered to be those that maximise the likelihood of the sample. In the context of the estimation of the parameters of SDEs, however, a closed-form expression for the likelihood function is rarely available and hence exact maximum-likelihood (EML) estimation is usually infeasible. The key research problem examined in this thesis is the development of generic, accurate and computationally feasible estimation procedures based on the ML principle, that can be implemented in the absence of a closed-form expression for the likelihood function. The overall recommendation to come out of the thesis is that an estimation procedure based on the finite-element solution of a reformulation of the Fokker-Planck equation in terms of the transitional cumulative distribution function(CDF) provides the best balance across all of the desired characteristics. The recommended approach involves the use of an interpolation technique proposed in this thesis which greatly reduces the required computational effort.
135

Maîtrise de la tenue en fatigue des cordons de soudure / Fatigue Life Assessment of Welded Joints

Coelho, Fabricio dal Cero 22 October 2014 (has links)
Les châssis automobiles sont composés en majorité de pièces mécano-Soudées soumises à deschargements multiaxiaux complexes. Par leur géométrie particulière et les transformations induites par leprocédé de fabrication, les joints soudés sont des sites privilégiés d’amorçage et de propagation de fissures enfatigue. Une méthode de calcul fiable et maniable représente un enjeu majeur pour l’industrie automobile, carelle permet de détecter les points critiques dès la phase d’avant projet, d’éviter le surdimensionnement et deréduire le nombre des prototypes physiques.Afin de découpler les incertitudes et permettre l’analyse isolée des effets induits par le chargementmultiaxial lui-Même et par les caractéristiques particulières du joint soudé, cette étude est divisée en deux parties.La première partie se concentre sur le chargement multiaxial complexe. Le comportement d’un « matériauécole », l’acier C35, est étudié sous spectre de chargement de type « automobile ». Différentes méthodes deprévision de la durée de vie sont ensuite comparées sous deux critères : la qualité de prédiction et la simplicitéd’utilisation. La deuxième partie est centrée sur l’étude du comportement des assemblages soudés et lasimulation de leur durée de vie. Pour ce faire, une éprouvette représentative des pièces de liaison au sol et duprocédé de fabrication a été conçue. L’étude micrographique de l’assemblage combinée à des essais instrumentésa permis de construire un modèle EF représentatif de la structure. Deux modes de sollicitation sont utilisés lorsdes essais de fatigue dans le but d’activer différents mécanismes de dommage en amplitude constante et enspectre « automobile ».Finalement, la méthodologie « Weld Stress Gradient » est proposée pour intégrer l’effet du gradient decontraintes en proximité des points critiques du joint soudé au calcul de fatigue. Cette méthodologie, associée aucritère de Vu (prise en compte du chargement complexe) et à la règle de cumul de dommage non linéaire« DCA » (prise en compte de l’interaction entre les blocs de chargement du spectre), permet d’obtenir desrésultats encourageants pour l’assemblage étudié. / Automotive chassis are composed mostly of welded parts subjected to complex multiaxial loadings.Welds are potential sites to initiation and propagation of fatigue cracks because of their particular geometry andtransformations induced by manufacturing process. A reliable and tractable fatigue design methodology is achallenge for automotive industry designers because it allows detecting the critical points from the upstreamphase, avoiding oversizing and reducing the number of physical prototypes.This study is divided into two parts allowing the distinction of effects induced by multiaxial loadingsand particular characteristics of the welded joints. The first part focuses on the complex multiaxial loading. Thebehavior of a “well known material”, the 1045 steel, is studied under "automobile" spectrum loading. Differentfatigue life prediction methods are compared under two criteria: quality of prediction and simplicity of use. Thesecond part focuses on the study of behavior and fatigue life simulation of welded structures. To achieve thisgoal, a representative specimen of chassis parts and manufacturing process has been designed. A representativeFE model is constructed, based on micrographic observations and instrumented tests. Two loading modes areused in fatigue tests in order to activate different damage mechanisms at constant amplitude and under"automobile" spectrum.Finally, the methodology "Weld Stress Gradient" is proposed to incorporate in fatigue analysis theeffect of the stress gradient at the vicinity of weld joints critical points. This methodology, combined with Vucriterion (taking into account complex loadings) and "DCA" nonlinear cumulative damage rule (taking intoaccount interaction between spectrum loading blocks), provides encouraging results for the studied specimen.
136

A literatura infantil como prática de letramento através da oralidade

Farias, Angelica Torres Vilar de 09 April 2014 (has links)
Made available in DSpace on 2015-05-14T12:43:14Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2139146 bytes, checksum: 9e187e84e45b7764d32fd45fab5ae376 (MD5) Previous issue date: 2014-04-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Reading is a theme frequently discussed in researches and in the academic environment. We intend with the present research, to analyze and reflect about the reading of infant literature which text are written as recreations of the oral textual genre that Cascudo (1984, p. 329) classifies as Cumulative Tale, in which refers to its approach, in the intention of literacy, in classes from fundamental teaching I. Specifically we intent to research about the oral expression and oral genres present in books of infant and juvenile literature founded at MEC libraries in public schools from Taperoá. We consider making a survey of books which texts would be ‗inspired or that revisited the thematic or the forms of oral expression of popular culture. We aimed to point representations of oral expression (explicit of implicit) in the texts chosen for analysis. This choice conducted the research to the analysis of these books, in the sense of support a pedagogical work, in the classroom, in order to increase the student s literacy process. It was observed, among other aspects referent to the oral expression in the classroom, that the mediation of reading realized by the teacher, with reading activities, will collaborate to these results. In this study, we are based in assumptions of Kleiman (1995, 2005, 2012), Geraldi (1996, 1997, 2001), Soares (2000, 2003, 2004, 2012), Dolz & Schneuwly (2004), Marcuschi (1997, 2001, 2003, 2005, 2010), Ong (1998) and Zumthor (2003, 2010). From a more ample universe of research, we analyzed a selection of four books of infant literature, which texts can be classifies as cumulative tales. The book s analysis provided an amplification of our vision about the importance of the oral expression that can be developed from readings of infant literature, in the literacy process of a subject. / A leitura é um tema frequentemente discutido no seio da sociedade e abordado em pesquisas, no meio acadêmico. Pretendemos, com a pesquisa que culmina com este trabalho, refletir sobre leitura de livros de literatura infantil cujos textos são redigidos como recriações do gênero textual oral que Cascudo (1984, p. 329) classifica como Conto Acumulativo, no que se refere à sua abordagem, na intenção do letramento, em turmas de ensino fundamental I. Especificamente, intencionamos pesquisar sobre oralidade e gêneros orais presentes em livros de literatura infantil e juvenil pertencentes ao acervo das bibliotecas do MEC, em escolas públicas de Taperoá. Consideramos fazer um levantamento dos livros cujos textos seriam inspirados ou revisitam temáticas ou formas orais de dizer da cultura popular. Buscamos apontar representações significativas de oralidade (explícitas ou implícitas) nos textos escolhidos para análise. A análise contemplou possibilidades de esses livros apoiarem um trabalho pedagógico, na sala de aula, com vistas a desenvolver atividades visando o letramento dos alunos, ou seja, observar a mediação do professor durante a leitura no sentido de favorecer esses resultados. Para tanto, baseamo-nos em estudos como os de Kleiman (1995, 2005, 2012), Geraldi (1996, 1997, 2001), Soares (2000, 2003, 2004, 2012), Dolz & Schneuwly (2004), Marcuschi (1997, 2001, 2003, 2005, 2010), Ong (1998) e Zumthor (2003, 2010). De um universo mais amplo pesquisado, ficou estabelecido um recorte de quatro livros de literatura infantil, cujas características os classificam como contos acumulativos. A análise dos livros à luz da mediação de leitura em sala de aula do Ensino Fundamental I demonstrou a importância das atividades orais que podem ser desenvolvidas utilizando livros de literatura infantil no processo de letramento das crianças envolvidas nesse processo.
137

Understanding human culture : theoretical and experimental studies of cumulative culture

Miu, Elena January 2017 (has links)
There is something extraordinary about human culture. The striking complexity of our technologies, institutions, beliefs, and norms has allowed us to colonise the entire planet. One aspect in which human culture is unique relates to its cumulative nature – we accumulate and build on knowledge from the previous generations, leading to incremental improvement in skill, which allows us to produce technologies no one individual could have invented on their own. Understanding the drivers and dynamics of this type of cumulative culture is essential for understanding how human culture has interacted with human evolution. This thesis is concerned with precisely that, and uses a mixture of theoretical and experimental approaches linking individual-level decisions to population-level processes in cumulative culture contexts. Chapter 1 provides some essential background information. In Chapter 2 I used an agent-based simulation model to show that refinement, or incremental improvement in cultural traits, can lead to a drastic decrease of cultural diversity at the population level. This pattern was confirmed using experimental data from a collaborative programming competition in Chapter 3, where I showed that in a cumulative setting, the differential riskiness of copying and innovation drives participants to converge on very similar solutions, leading to a loss of cultural diversity. In Chapter 4 I explored individual differences in social learning strategies, finding considerable variation in how individuals rely on copying, with more successful individuals being more exploratory. I found that successful individuals had more influence on subsequent entries, which is consistent with a prestige bias. Finally, Chapter 5 addressed the link between group structure, diversity, and cumulative improvement. I found that larger groups accumulate more improvement than smaller groups, but smaller groups can also inhibit the convergence patterns we witnessed in larger groups, suggesting an optimal level of connectivity responsible for cumulative improvement.
138

Política e finanças : um estudo sobre o impacto das contribuições a campanhas políticas nas empresas brasileiras

Davi, Mariana Gesswein January 2016 (has links)
Este trabalho visa identificar possíveis vantagens que as empresas obtêm ao contribuir com campanhas políticas. Para isso, foi utilizada uma extensa base de dados com informações de doações a candidatos aos cargos de deputado, senador e presidente nas eleições de 2006 e 2010. As variáveis de interesse analisadas foram o retorno anormal cumulativo à época da divulgação do resultado das eleições e o retorno sobre o patrimônio líquido no ano posterior a cada eleição. Foram estimadas regressões de dados em painel através de mínimos quadrados ordinários, e incluídos efeitos fixos de ano e setor das empresas. Os resultados indicam que não apenas o mercado antecipa benefícios futuros para as empresas que contribuíram com campanhas – o que se reflete em retornos anormais cumulativos positivos à época da eleição – mas também estas empresas apresentam retornos sobre o patrimônio líquido superiores aos daquelas que não participaram do processo político. Além disso, doações a candidatos vencedores geram retorno superior aos de doações a candidatos perdedores; o que vai ao encontro da hipótese de retribuição de favores. De forma similar, contribuições a candidatos filiados à coligação do presidente eleito também apresentaram impacto superior quando comparadas com doações a candidatos da oposição. / This paper aims to identify potential benefits that companies obtain by contributing to political campaigns. We used an extensive database with information on donations to House, Senate and Presidency candidates in the 2006 and 2010 elections. The variables of interest analyzed were the cumulative abnormal return by the time the results of each election became know and the return on equity in the year following the election. Panel regressions were estimated as ordinary least squares (OLS), and fixed effects of year and industry were included. The results indicate that not only the market anticipates future benefits for companies that contributed to campaigns - which is reflected in positive cumulative abnormal returns at the announcement of the election results - but these companies also have higher returns on equity than those that were not involved in the political process. In addition, donations to winning candidates generate higher returns than donations to losing candidates; which supports the return of favors hypothesis. Similarly, contributions to candidates affiliated to the president’s coalition's also had higher impact when compared to donations to the oposition candidates.
139

Temperament differences during the first year of life in infants at high-risk for autism spectrum disorder

Hardiman, Kelsey 08 April 2016 (has links)
With the growing number of children who receive a diagnosis of Autism Spectrum Disorder (ASD), there is an increasing need to identify risk markers that will allow for earlier diagnosis of this disorder. Since no single atypical behavior has been found that is shared by all 12-month-old infants who are later diagnosed with ASD, it is likely that a constellation of markers combine in a way that is more predictive of outcome at this age. Establishing a Cumulative Risk Index (CRI) is one way to investigate which combination of early risk markers is most predictive of later ASD diagnostic outcome. Temperament is one construct of behavior that could act as an early risk marker for ASD and therefore, could add predictive power to a CRI for this disorder. Temperament is defined as a "behavioral style" that includes individual differences in reactivity and self-regulation and emphasizes emotional, attentional and activity related characteristics. Another important aspect of temperament is that it exerts bidirectional influences upon the social environment. Therefore, the study of temperament could provide a method for understanding how children with ASD influence and are influenced by the environment of a testing session. Though important information has been collected about early temperament in children with ASD, much of the data is limited due to its dependence on retrospective and parent-report measures. One measure that allows for direct assessment of temperament during a controlled testing session is the Infant Behavior Record (IBR). The purpose of this study is to investigate early temperament in ASD by using the IBR as an assessment of temperament behaviors in high-risk 12-month old infants. Through this, we hope to reveal group differences in IBR scores, establish a relationship between temperament scores and cognitive test performance, and increase predictive value of the CRI when IBR scores are included. For this study, a revised version of the IBR was filled out while watching video record of the administration of the Mullen Scales of Early Learning (MSEL) at an infant's 12-month lab visit. Scores for the IBR reflected the examiner's impressions of the infant's orientation to objects and people and emotional state. Through using the IBR to study task orientation (TO), affect/extraversion (AE) and activity level (AL) in high-risk infants, this study found that only decreased AE behaviors distinguished high-risk infants who went on to develop ASD (HRA+ASD) from high-risk infants who did not receive an ASD diagnosis (HRA-ASD) (p=.08). To determine the relationship of temperament and cognitive assessment performance, IBR scores were compared to MSEL scores. This study found that across all participants, TO and AE behaviors were positively correlated with MSEL scores (AE rs=.27, p<.001; TO rs=.37, p<.001). This relationship remained true for both the high-risk (AE rs=.20, p<.001; TO rs=.23, p<.001) and the low risk groups (AE rs=.32, p<.001; TO rs=.54, p<.001), as well as for the HRA-ASD infants (AE, trend, p=.057; rs=.24, p<.001; TO rs=.459, p<.001), and the low-risk infants who did not go on to receive a diagnosis of ASD (AE rs=.35, p<.001; TO rs=.47, p<.001). The only group in this study that was found to have no correlations between temperament scores and MSEL scores was HRA+ASD. Since only AE behaviors distinguished HRA+ASD infants, this was the only IBR factor added to a pilot model of the CRI. This study found that the inclusion of AE to a pilot model of the CRI did not add significant predictive value to the model (p=.15). Through using the IBR to investigate temperament in HRA infants, the findings of this study suggest that there are some important differences in temperament behaviors for HRA+ASD infants. Specifically, reduced AE behaviors seem to distinguish the HRA+ASD infants from the other outcome groups. Also, this study found that increased TO and AE behaviors were associated with better performance on a cognitive assessment for all groups except HRA+ASD. These two findings are important, as they differentiate this outcome group from all others, suggesting that there may be a different set of mechanisms employed during a testing session for HRA+ASD infants. This study also found that AE risk did not contribute predictive value to a CRI for this disorder. Taken together these findings suggest that though temperament profiles appear to differ in HRA+ASD infants during the first year of life, this construct of behavior is not a valuable early behavioral risk marker for identifying ASD.
140

Study of Deflection of Single and Multi-Storey Light Frame Wood Shear Walls

Bagheri, Mohammad Mehdi 01 August 2018 (has links)
The behavior of wood shear walls has been the focus of researchers and engineers for many years due to their availability in the North American construction landscape. A review of the established literature showed that most of the research have focused on the shear wall behavior as a whole with no investigation specifically targeting the individual components of its deflection. Also, little to no attention has been given to the investigation of the cumulative effects especially when the out-of-plane diaphragm stiffness is considered. The current study aims at investigating the effects of construction details variation on the behavior of the shear walls and evaluating whether the current deflection equation, as per wood design standard (CSA 2014) can adequately predict the overall wall stiffness. A total of 27 full-scale single-storey walls, with different construction details and aspect ratios, were tested under either static or monotonic (as both are the same) loading. The parameters that were varied in the testing were the stud size and spacing, nail diameter and spacing, sheathing panel type and thickness and hold-down anchoring system/type. For the two-storey walls, two different loading cases were considered, namely where the load was applied at the top or bottom storey only. The results showed that the strength and stiffness correlated almost directly to the inverse of the wall aspect ratio. There was no clear trend when considering the effect of the walls’ aspect ratios on ductility. Unexpectedly, walls with aspect ratios not permitted according to the wood design standard (4:1 and 6:1) followed similar strength and stiffness trends and had sufficient ductility ratios as those with smaller aspect ratios. This observation explains in part some of the discrepancies found between engineering calculations and behavior of actual building with light frame wood shear walls. Significant discrepancies were found when comparing the various deflection constituent with those estimated using the design expression. Adding more end studs and changing the size of the studs had no significant effect on the overall wall capacity and little effect on its stiffness. Reducing the stud spacing had, as expected, no effect on the wall capacity; however, the results showed that the bending stiffness was affected by the overall number of studs in the wall and not solely by the end studs. Shear walls sheathed with plywood panels exhibits slightly higher peak load and initial stiffness than those with OSB, which was mainly attributed to the greater panel thickness, and possibly density, of the plywood. Both sheathing types provided similar levels of ductility, as expected. Thicker sheathing increased the capacity and stiffness of the wall with no significant change observed in ductility ratio. The wall strength was significantly affected by the nail diameter and nail spacing, but no difference was observed when the nail edge/end distance was increased. The results also showed that discrete hold-down system behaved in a non-linear manner with a significantly greater initial stiffness than that assumed in design. The study also showed that having continuous hold-down connections has a positive effect on the capacity, stiffness and ductility of the wall when compared with discrete hold-downs. Having no hold-down adversely affects the wall capacity and stiffness, but did not affect the ductility of the wall. For the two-storey walls, the deflection estimated based on the cumulative effect assumption showed slight differences when compared with that observed in the experimental study. It was observed that the majority of the cumulative effect stems from the rigid body rotation due to deformation in the hold-down devices. A Computer shear wall model (through SAP2000) was developed using linear “frame” and “membrane” elements for the framing and sheathing members, respectively, whereas the sheathing to framing nails and hold-down were modeled using nonlinear springs. It was found that the model was capable of predicting the peak load, ultimate deflection and yield loads with reasonable accuracy, but overestimated the initial stiffness and ductility of the walls. In general, when the force-displacement curves were compared it was evident that the model was capable of predicting the wall behaviour with reasonable accuracy. When investigating the cumulative effects using the model, the results clearly showed that the assumption of cumulative effects due to rigid body rotation is valid for stacked shearwalls with no consideration for the floor diaphragm. The effect of the diaphragm on the behavior of the shear walls, in particular its out-of-plane rigidity was simulated by modeling the floors as beam. The out of plane stiffness of the shear walls was investigated for idealized (infinitely stiff or flexible) as well as “realistic”. The results showed reductions in the shearwall deflection in the magnitude of approximately 80% considering the out of plane rigidity of the diaphragm. It was also concluded that considering conservative estimates of out of plane stiffness might lead to a very significant reduction in deflection and that assuming the floor diaphragm to be infinitely rigid out of plan seems reasonable. For diaphragms supported on multiple panels further reduction in the deflection was observed. More work, particularly at the experimental level, is needed to verify the finding obtained in the numerical investigation related to the effect of out of plane diaphragm stiffness.

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