Browsing by Author "Eden, Shiferaw"

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    Effect of Layered Reinforcement Arrangement on Deformation and Cracking of Reinforced Concrete Beams
    (Addis Ababa University, 2020-09) Eden, Shiferaw; Bedilu, Habte (PhD)
    The purpose of this work is to study the effect of layered reinforcement arrangement on the deformation and cracking of reinforced concrete beams in both flexural and tensile loading. The study is based on analytical simulation of four flexural beams and eleven tensile beams in objective of studying the response and behavior of concrete and reinforcement with different arrangements of reinforcements. Even though experiments observed in different literatures show a good agreement with code predictions, there are still inadequacies in predicting reinforced concrete elements cracking behavior with different arrangements of reinforcement bars. In order to increase adequacy of serviceability results related with effect of reinforcement bar arrangement on reinforced concrete elements cracking behavior, detailed assessment is required. The analytical simulation was attempted using a non-linear finite element tool called ABAQUS CAE for beams with different arrangement of reinforcement bars and different concrete grades. Results of simulation from flexural elements showed that different reinforcement layouts show correlation with flexural stiffness and do not show direct relationship with reinforced concrete structures cracking behavior. Considering the tensile members, the strain observed in the specimens varies not only along the bar but also with in the surface of the concrete section. Adequacy of evaluating the cracking behavior in the members is closely associated with assessing the strain in the concrete since the strain in the reinforcements is similar in the cases considered.
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    Modeling Inflation Volatility and its Effect on Economic Growth in Ethiopia
    (A.A.U, 2012-06) Eden, Shiferaw; Fantu, Guta (Dr)
    Inflation volatility is a serious problem in the conduct of monetary policy. This is because it makes economic planning difficult, affects investment decision and hence growth. This study is aimed at modeling inflation volatility and analyzes its effect on economic growth in Ethiopia. The study uses quarterly data on Consumer Price Index (CPI) and Gross Domestic Product (GOP) for the period 1991 /92 -2010/ 11 . To model inflation volatility as time varying process an extended form of GARCH (Generalized Autoregressive Conditional Heterosedasticity) model i.e. Threshold GARCH is used. The study finds strong evidence for the existence of Freidman-Ball hypothesis. TGARCH model is used to allow for asymmetric effect of positive and negative inflationary shocks and the result indicates strong asymmetric effect of inflationary shocks on inflation uncertainty. Co integrated VAR model and granger causality test are also used to see the relationship between inflation, inflation uncertainty and growth. From the cointegrated VAR model the growth rate of GOP affects inflation positively in the long run and negatively in the short run. The granger causality result indicates that inflation granger causes inflation uncertainty positively and inflation uncertainty granger causes output growth negatively. To prevent the negative consequences of inflation including uncertainty problem National Bank of Ethiopia (NBE) should restore public confidence via credible policy instruments. Furthennore detennining the threshold level of inflation-gro:vth relationship is important • to know the type of relationship that exists between growtl'i and ~n.