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Upgrade of Seismically Deficient Steel Frame Structures Built in Canada Between the 1960s and 1980s Using Passive Supplemental DampingKyriakopoulos, Nikolas 20 November 2012 (has links)
A typical 1960s Type 2 Construction steel MRF hospital structure in Quebec,
representative of a prevalent construction philosophy of the time, was investigated and
modelled in OpenSees using an advanced strength degradation model. The structure
was then subjected to a nonlinear time-history analysis (NLTHA) for Montreal (MTL)
and Vancouver (VAN) ground motions and was found to be deficient under the design
hazard levels. Retrofits were proposed for the two orthogonal frames at both sites
using a performance-based approach. An experimental program determined that the
connections had less ductility than expected and began deteriorating around 2.0%
interstorey drift. The OpenSees model was updated according to the experimental
connection behaviour and the predicted NLTHA performance of the structure
worsened. The proposed retrofit designs for both orthogonal frames in both MTL and
VAN were updated with the new connection behaviour and final retrofit designs were
proposed.
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Upgrade of Seismically Deficient Steel Frame Structures Built in Canada Between the 1960s and 1980s Using Passive Supplemental DampingKyriakopoulos, Nikolas 20 November 2012 (has links)
A typical 1960s Type 2 Construction steel MRF hospital structure in Quebec,
representative of a prevalent construction philosophy of the time, was investigated and
modelled in OpenSees using an advanced strength degradation model. The structure
was then subjected to a nonlinear time-history analysis (NLTHA) for Montreal (MTL)
and Vancouver (VAN) ground motions and was found to be deficient under the design
hazard levels. Retrofits were proposed for the two orthogonal frames at both sites
using a performance-based approach. An experimental program determined that the
connections had less ductility than expected and began deteriorating around 2.0%
interstorey drift. The OpenSees model was updated according to the experimental
connection behaviour and the predicted NLTHA performance of the structure
worsened. The proposed retrofit designs for both orthogonal frames in both MTL and
VAN were updated with the new connection behaviour and final retrofit designs were
proposed.
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573 |
The Framing of China's Bird Flu Epidemic by U.S. Newspapers Influencial in China: How the New York Times and The Washington Post Linked the Image of the Nation to the Handling of the DiseaseSong, Ning 07 August 2007 (has links)
This study conducted a framing research that analyzed coverage of the bird flu (avian flu) in China by two major American newspapers that are influential in China (The New York Times and Washington Post). The goal was to examine how these two prestigious newspapers frame the bird flu epidemic in China and how they represent the country in this international health crisis. This study employed textual analysis regarding the way bird flu news articles were framed in terms of problem definition, causal explanation, moral evaluation and solution recommendations in both newspapers. The study found the epidemic was framed as more than just a public health crisis. Multiple news frames were found in both newspapers' coverage of bird flu, depicting the event as a cultural, social and political crisis to the nation and to the world.
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Occupy Wall Street in alternative and mainstream media : A comparative analysis of the social movement’s framing in the mediaNegus, Andra Stefania January 2012 (has links)
The thesis provides an analysis of the different ways the Occupy Wall Street was presented by OccupyWallSt.org ( the movement’s own media source), and The New York Times, The Wall Street Journal and USA Today from July 2011 up to the end of June 2012. This was done by using Entman’ theory of media framing together with Castells’ network theory of power. The former provided a way of addressing the different types of frames that mainstream media utilize, while the latter offered an understanding of how power is built through the media processes. Additionally, Castells’ theory described another type of media frame which is mostly used by alternative media, the counter frame, which could successfully be applied to study the content that the social movement decided to provide about itself.The study first employs a quantitative approach by using Crawdad, a centering resonance analysis (CRA) software. This provides a reliable pool of data that was then analyzed by using the above theories. Additionally, in order to check the reliability of the qualitative conclusions, a statistical test was done for the overall top centers resulting from the CRA.
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Cognitive dissonance, mental frames and the financial value of agricultural co-operativesLamprinakis, Lampros 05 June 2008 (has links)
<p>The co-operative as an economic and social institution has long been recognized for its contribution to economic development as well as its positive effect on local communities. However, over the last decade or so substantial structural changes in the agricultural sector have undermined some of the most prominent North American co-operatives. In some cases, co-ops asked for bankruptcy protection, others ceased operations while some were transformed to for-profit firms. The present study offers three essays that explore the challenges that co-operatives are facing in terms of their relationship with their members in local markets, the decision-making process of their leaders and the co-ops' role in the modern economy.</p>
<p>These first two essays are linked by the fact that they both develop models that are about cognitions. Examining cognition offers some new insights to understanding the process behind the decline of agricultural co-ops. In the first essay the model examines consumers' cognitions, while the model in the second essay examines management's cognitions. The essays differ on the agent's ability to change the perceptions that result from those cognitions. Essay One assumes that consumers' perceptions are partially flexible and thus can change over time with some cost; on the other hand, essay Two assumes that beliefs are inflexible due to the high cost of changing them.</p>
<p>Essay One examines the relationship between a co-operative and its membership in a local market using an economic psychological approach. More specifically, the essay presents a modified rational-choice model to investigate how cognitive dissonance can influence members' loyalty. The effect of cognitive dissonance is analyzed in a case where a local co-operative operates alongside with an investor-owned firm (IOF) in a market. The model illustrates how cognitive dissonance can give rise to switching costs for those consumers who wish to switch to the IOF. Analytical results demonstrate the effect of these switching costs on equilibrium market shares and discuss how a drop in the dissonance cost because of managerial decisions by the co-op can result in dramatic drops in its market share.</p>
<p>Essay Two illustrates how management's mental frame can be incorporated into an economic model and develops a theoretical underpinning for the link between a strong mental frame and the financial difficulties that a firm might experience. The case of the Saskatchewan Wheat Pool with its Project Horizon plan is proposed as an example of a situation where the established mental frame gave rise to a belief regarding future member support that had a significant influence on the decision-making process of the co-op's CEO. The analysis includes a game theoretic model of a duopoly between a co-operative and an IOF, where mental framing is explicitly incorporated into the primitives of the model. Analytical results illustrate how the CEO's belief regarding member commitment can influence decision-making and therefore affect the market share and profits of the firm.</p>
<p>Essay Three uses non-parametric econometric techniques to examine the stock price effect of a co-op's acquisition by a publicly-traded IOF. The potential for this study emerged as a result of the takeover of Dairyworld, a dairy co-op, by Saputo, a publicly-traded private corporation. The study uses the prediction-error approach to estimate Saputo's returns after the acquisition as a deviation from its expected returns. A non-parametric bootstrap technique simulates Saputo's stock returns and examines its behavior around the acquisition date. The empirical results are consistent with a number of hypotheses, including the pro-competitive role that co-operatives are believed to have in the economy. The essay also includes a comprehensive discussion regarding the greater financial value that co-ops have for IOFs.</p>
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PReklam? : En kvantitativ studie som undersöker vad gymnasieelever i årskurs 3 förknippar med begreppet PRPogarcic, Dajana, Moberg, Jessie January 2011 (has links)
Background and aim: Media development and digitalization has expanded the PR industry's working area. More participants are on the media market and it is becoming more and more difficult to define what PR really is and what the PR agencies/departments really do. Is PR marketing, information, event marketing or maybe propaganda? We believe that the complexity to define the term PR can lead to a loss of critical approach to the business, especially among young people. Has the PR industry managed to eliminate their negative image among students in upper secondary school and what do they associate with PR today? The aim of this essay is to examine what a selection of students associate with the term PR and if they are critical to the PR industry or not. Method/Material: The method is a quantitative survey. The target group is senior students in upper secondary public school in central Stockholm. Theory: Social construction, PR-theory, framing and former studies about the students and general public opinion about the PR business. PR background, PR expansion in Sweden, Definition of PR, Social media and PR, PR’s relationship with propaganda, democracy, marketing Main Results: Our target group associates PR with advertisements, commercials and ads. The majority is neither critical nor uncritical to the PR industry.
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Optimal Wind Bracing Systems For Multi-storey Steel BuildingsYildirim, Ilyas 01 August 2009 (has links) (PDF)
The major concern in the design of the multi-storey buildings is the structure to have enough lateral stability to resist wind forces. There are different ways to limit the lateral drift. First method is to use unbraced frame with moment-resisting connections. Second one is to use braced frames with moment-resisting connections. Third one is to use pin-jointed connections instead of moment-resisting one and using bracings. Finally braced frame with both moment-resisting and pin-jointed connections is a solution.
There are lots of bracing models and the designer should choose the appropriate one. This thesis investigates optimal lateral bracing systems in steel structures. The method selects appropriate sections for beams, columns and bracings, from a given steel section set, and obtains a design with least
weight. After obtaining the best designs in case of weight, cost analysis of all structures are carried out so that the most economical model is found. For this purpose evolution strategies optimization method is used which is a member of the evolutionary algorithms search techniques.
First optimum design of steel frames is introduced in the thesis. Then evolution strategies technique is explained. This is followed by some information about design loads and bracing systems are given. It is continued by the cost analysis of the models. Finally numerical examples are presented. Optimum designs of three different structures, comprising twelve different bracing models, are carried out. The calculations are carried out by a computer program (OPTSTEEL) which is recently developed to achieve size optimization design of
skeletal structures.
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Nonlinear Analysis Of Rc Frames Retrofitted With Structural Steel ElementsAkpinar, Ugur 01 September 2010 (has links) (PDF)
Deficient concrete structures are serious danger in seismic zones. In order to minimize economical and human loss, these structures should be retrofitted. Selecting suitable retrofitting schemes requires detailed investigation of these systems. Considering these facts, this study aims to calibrate analytical models of systems with chevron braces and internal steel frames / and evaluate their seismic performances. First, analytical models of the frames with braces and internal steel frames were prepared and then their responses were compared with cyclic responses of experimental studies. Results of these models were used to determine performance limits by the methods proposed by TEC2007 and ASCE/SEI-41. Then, calibrated models were employed for time history analyses with various scales of Duzce ground motion and analytical results were compared with experimental findings. Seismic performance of these systems was also evaluated by using aforementioned codes. Finally, evaluated retrofitting schemes were applied to a 4-story 3-bay reinforced concrete frame that was obtained from an existing deficient structure and effectiveness of applied retrofitting schemes was investigated in detail.
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Seismic Upgrading Of Reinforced Concrete Frames With Structural Steel ElementsOzcelik, Ramazan 01 June 2011 (has links) (PDF)
This thesis examines the seismic internal retrofitting of existing deficient reinforced concrete
(RC) structures by using structural steel members. Both experimental and numerical studies
were performed. The strengthening methods utilized with the scope of this work are chevron
braces, internal steel frames (ISFs), X-braces and column with shear plate. For this purpose,
thirteen strengthened and two as built reference one bay one story portal frame specimens
having 1/3 scales were tested under constant gravity load and increasing cyclic lateral
displacement excursions. In addition, two ½ / scaled three bay-two story frame specimens
strengthened with chevron brace and ISF were tested by employing continuous pseudo
dynamic testing methods. The test results indicated that the cyclic performance of the Xbrace
and column with shear plate assemblage technique were unsatisfactory. On the other
hand, both chevron brace and ISF had acceptable cyclic performance and these two
techniques were found to be candidate solutions for seismic retrofitting of deficient RC
structures. The numerical simulations by conducting nonlinear static and dynamic analysis
were used to estimate performance limits of the RC frame and steel members. Suggested
strengthening approaches, chevron brace and ISF, were also employed to an existing five
story case study RC building to demonstrate the performance efficiency. Finally, design
approaches by using existing strengthening guidelines in Turkish Earthquake Code and
ASCE/SEI 41 (2007) documents were suggested.
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Optimum Design Of Steel Structures Via Differential Evolution Algorithm And Application Programming Interface Of Sap2000Dedekarginoglu, Ozgur 01 March 2012 (has links) (PDF)
The objective of this study is to investigate the use and efficiency of Differential Evolution (DE) method on structural optimization. The solution algorithm developed with DE is computerized into software called SOP2011 using VB.NET. SOP2011 is automated to achieve size optimum design of steel structures consisting of 1-D elements such as trusses and frames subjected to design provisions according to ASD-AISC (2010) and LRFD-AISC (2010). SOP2011 works simultaneously with the structural analysis and design software SAP2000 in order to find the global or near optimum designs for real size truss and frame structures in which the optimization problem is classified as constrained, discrete size optimization. Software interacts with SAP2000 through the Open Application Programming Interface (OAPI), which provides an access to information of SAP2000 inputs and outputs. It is programmed for finding reasonable and optimized results for truss and frame steel structures by choosing appropriate ready sections for structural members considering the minimum weight via DE technique.
Based on the comparison of the obtained results with the literature, DE algorithm with penalty function implementation is proved to be an efficient optimization technique amongst several major methods used for discrete constrained size optimization of real size steel structures. Also, it has been shown that by using optimized designs obtained by DE, weight of the structures can be reduced up to 67.9% for steel truss structures and 41.7% for steel frame structures compared to SAP2000 auto design procedure, hence resulting a significant saving of materials, cost, work hours and energy required for the project.
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