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Concept of Value Engineering and Current Project Management Practice in Ethiopian Building Construction Projects
Tsigereda Garomsa,
Elmer De Castro Agon,
Sintayehu Assefa
Issue:
Volume 7, Issue 1, January 2019
Pages:
1-8
Received:
30 December 2018
Accepted:
12 February 2019
Published:
27 February 2019
Abstract: In construction projects, when one-program costs more than planned, decision makers are forced to delay or cancel other activity. Value Engineering can play a key role in overcoming such problems by ensuring programs stay within project duration, estimated budget and saving costs. This study was conducted to assess the applicability of value engineering concept and the current management practice of Ethiopian building construction projects. In this study, knowhow of Ethiopian building construction project experts on value engineering principles were studied and the current management practice was examined. In order to gather required information, questionnaire, interview with project managers and archival review was conducted. Data was analyzed both qualitatively and quantitatively. The result of this study shows, main challenges in the project area were: delay in progress payment by owner, poor site management, weak follow up by consultant, and delay in material delivery from contractor side. Almost all experts in the project have no knowledge on the principle of value engineering and has no willingness to implement the principle. The evaluation made using value engineering principle shows the current management practice was more conventional and the industry is still facing delay of projects, cost overrun and poor quality while there are opportunities to minimize such problems.
Abstract: In construction projects, when one-program costs more than planned, decision makers are forced to delay or cancel other activity. Value Engineering can play a key role in overcoming such problems by ensuring programs stay within project duration, estimated budget and saving costs. This study was conducted to assess the applicability of value engine...
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Development of a Self-balanced Rock True Triaxial Compression Instrument
Tang Yanchun,
Wang Yue,
Liu Ruilong,
Zhou Hui,
Mao Qingfeng
Issue:
Volume 7, Issue 1, January 2019
Pages:
9-16
Received:
25 December 2018
Published:
8 March 2019
Abstract: Based on the analysis of the structure and the performance of similar instruments at home and abroad, a Self-balanced Rock True Triaxial Compression instrument (SRT) was developed. For SRT, complex stress realization, based on three-dimensional stress alone control and change; and the self-balanced structure is adopted on the basis of frame design, which makes the instrument simple and compact; design of lateral composite press plate with embedded rolling roller, the influence of test results on the effect of friction on the side end surface of the specimen under lateral stress constraint can be eliminate effectiveness; The design scheme of transverse double sliding rod is adopted, its validity can be designed by horizontal alignment, and the problem of eccentric compression of specimen can be partly alleviated in horizontal direction. By changing the alkali of the mothed triaxial chamber, both true triaxial and conventional triaxial compression can be tested. Test results of true triaxial and conventional compression of rocks with different lithology were carried out by SRT. The results, such as the deformation and failure characteristics of rock strength in complex stress conditions, have been obtained by SRT, which indicates that the design of SRT is feasible and feasible. The development of this instrument can promote the further development of Chinese rock triaxial testing machine.
Abstract: Based on the analysis of the structure and the performance of similar instruments at home and abroad, a Self-balanced Rock True Triaxial Compression instrument (SRT) was developed. For SRT, complex stress realization, based on three-dimensional stress alone control and change; and the self-balanced structure is adopted on the basis of frame design,...
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Production of Lightweight Concrete Using Corncob Ash as Replacement of Cement in Concrete
Sintayehu Assefa,
Mamaru Dessalegn
Issue:
Volume 7, Issue 1, January 2019
Pages:
17-20
Received:
11 February 2019
Accepted:
11 March 2019
Published:
25 March 2019
Abstract: One of the biggest issues, all over the world is getting affordable house to the community. In developing countries, where it is difficult for most people to satisfy basic needs, construction of modern house is a big challenge. Different ways were tried by researchers and scholars to find alternative construction materials. One of this is replacing the costly construction material of cement with locally available material, especially with those considered as waste. Corncob is an agricultural waste, which is considered as one of binding materials. Very few researchers tried to use corncob ash as a means of producing lightweight concrete. So, this research was aimed to check whether corncob ash is used to produce lightweight concrete by replacing cement as a binding material or not. In order to reach on conclusion, corncob was collected from agricultural farmers and burned in furnace at a temperature of 850°C. The burned ash powder was sieved in order to remove coarser material and replacement of cement was done by 5%, 10%, 15%, 20%, 25%, 30%, and 35% with corncob ash. For each replacement, including control, 3 samples were prepared based on ASTM standards. After curing for 7 and 28 days in curing tank, the weight and compressive strength of samples were checked. Based on the experimental result, as the percentage of corncob ash increase, the weight of cubes decreased and 15% and above corn cob ash replacement makes concrete cubes lightweight. The compressive strength was also decreasing as the amount of replacement increase. However, up to 15% replacement, compressive strength is found within the range of concrete grade requirement.
Abstract: One of the biggest issues, all over the world is getting affordable house to the community. In developing countries, where it is difficult for most people to satisfy basic needs, construction of modern house is a big challenge. Different ways were tried by researchers and scholars to find alternative construction materials. One of this is replacing...
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A Logistic Model Predicting Occurrence Probability of Debris Flow
Issue:
Volume 7, Issue 1, January 2019
Pages:
21-26
Received:
17 January 2019
Published:
28 April 2019
Abstract: This paper presents a logistic model for predicting the occurrence probability of debris flows based on rainfall intensity and duration. The data from a total of 354 rainfall events were used to calibrate the model, among which 249 were triggering a debris flow while 105 were not. The model will be useful to the decision making of debris flow early warning in the future. That is, given the estimated occurrence probability = 70% subject to a combination of rainfall intensity and duration, there is a 30% probability that the early warning will be a false alarm. By contrast, if decision makers decide not to issue an early warning, then there is a 70% chance leading to a missed alarm. Subsequently, integrating the consequences of missed alarm and false alarm into the equation, the respective risks can be computed, based on which decision makers can make a more robust decision whether an early warning is needed or not by choosing the scenario with a lower risk.
Abstract: This paper presents a logistic model for predicting the occurrence probability of debris flows based on rainfall intensity and duration. The data from a total of 354 rainfall events were used to calibrate the model, among which 249 were triggering a debris flow while 105 were not. The model will be useful to the decision making of debris flow early...
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Rules Regulating the Change in Physiological Parameters of Rats Under Simulated Microgravity and Different Ambient Temperatures
Jie Qian,
Gengxin Xie,
Jie Zheng,
Bo Duan,
Yajun Cao,
Xi Wang,
Fengjie Li,
Changpeng Hu
Issue:
Volume 7, Issue 1, January 2019
Pages:
27-34
Received:
18 January 2019
Published:
28 April 2019
Abstract: To investigate the rules regulating changes in mean chest temperature (MCT), mean rectal temperature (MRT) and mean body weight (MW)in rats at simulated microgravity and different ambient temperatures (ATs). The −30º rat tail suspension (TS) method was used to simulate microgravity over a 7 day period at 18°C, 20°C, 23°C and 26°C AT through comparison between the TS group and control group. Each group contained six male SD rats (including one verification rat). MCT and MRT of TS group rats increased at all four levels of AT. MCT and MRT reached maximum growth rates of 0.315 and 0.118 at ATs of 20°C and 23°C, respectively. MW was reduced at ATs of 20°C and 23°C, whereas it increased at 18°C and 26°C AT in the TS group. The rates of changes of MCT, MRT and MW at different ATs were analyzed using linear regression analysis for both the control (Equation 1) and TS (Equation 2) groups. Using A new equation (Equation 3) without the influence of other factors was derived after Equation 1 minus Equation 2 to derive. The result shows that the coefficients of Equation 3 are different under the four ATs. TS and AT have coupling effects on the MCT, MRT and MW of rats.
Abstract: To investigate the rules regulating changes in mean chest temperature (MCT), mean rectal temperature (MRT) and mean body weight (MW)in rats at simulated microgravity and different ambient temperatures (ATs). The −30º rat tail suspension (TS) method was used to simulate microgravity over a 7 day period at 18°C, 20°C, 23°C and 26°C AT through compari...
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The Finite Element Analysis of the Differential Settlement Prediction for the Adjacent Longitudinal Precast Box Culvert
Zenagebriel Gebremedhn,
Jilong Li,
Guofu Qiao
Issue:
Volume 7, Issue 1, January 2019
Pages:
35-40
Received:
14 March 2019
Published:
28 April 2019
Abstract: This paper presents the finite element analysis of the differential settlement prediction for the adjacent longitudinal precast box culvert and subject to different loading conditions including different loading area. These culverts were investigated based on the finite element method was used to analyze the numerical solution of the problems under the condition of assembled of the standard three dimensional adjacent box culvert with beneath soil, side soil and floor reaction under different loading conditions and loading areas. It is located on right side soil of box culvert concerning to settlement which is using brick element in ABAQUS software. The culvert, floor reaction and soil were modeled using standard parameters of three dimensional solid geometric and material linearity. Finally, the settlement foundation was predicted using the finite element modeling and analysis, the screw bolt constraint is equivalent to the binding contact (tie constraint) so that the screw bolt connection has a negative impact on the performance of the side wall of adjacent longitudinal box culvert specifically if there is a settlement occurred.
Abstract: This paper presents the finite element analysis of the differential settlement prediction for the adjacent longitudinal precast box culvert and subject to different loading conditions including different loading area. These culverts were investigated based on the finite element method was used to analyze the numerical solution of the problems under...
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