Civil and environmental research最新文献

{"title":"Assessing the Suitability of Bromilow Time-Cost (BTC) Model to Predict Project Time on Road Construction Projects in Botswana","authors":"Aderemi Y. Adeyemi, Bakang T. Motlakase","doi":"10.7176/cer/12-12-04","DOIUrl":"https://doi.org/10.7176/cer/12-12-04","url":null,"abstract":"The construction industry researchers have still found the Bromilow Time-Cost performance model given by T = KC B very relevant to today’s construction processes. The only aspects that change in the model are the coefficient of the equation K, and the power of the cost B. This suggests that the equation characteristics only change with the type of project and the environment in which the project was executed. The model helps to forecast the duration of a project using the estimated final cost of the project. A fast estimate of construction time in the early phase of a project helps the contractor in avoiding time and cost overruns that might lead to dispute and possibly litigation. The motivation for this research was derived from the above assertions. Data for formulating the Bromilow model for road construction projects were collected from a sample of 54 road projects executed by the Botswana Department of Roads. Analysis showed that the Bromilow time-cost performance model for road construction project in Botswana is given by: T = 14. 11116C 0.155488 With R 2 = 0.283266 and adjusted R 2 = 0.269483. Even though the R 2 and the adjusted R 2 were considered a good fit for the data and the R 2 was within the range of what was found in the previous studies around the world which is between 0.205 and 0.850, the model may not provide a good base in Botswana for estimating the duration of a project at the early life when the early cost is known. It is recommended that data on recently completed projects be provided for in-depth analysis of the influence of variables such as funding, payment, rework, change orders , and many other agents of time-overruns might have contributed to project time in the Botswana construction industry. Keywords: suitability , Bromilow’s model, project time, road construction projects, Botswana DOI: 10.7176/CER/12-12-04 Publication date: December 31 st 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"132 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90716809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Fire on Carrying Capacity of Concrete Columns Confinement with Multi-Layers of CFRP","authors":"E. M. Takla, Dr. Ihssan Tarsha","doi":"10.7176/cer/12-12-01","DOIUrl":"https://doi.org/10.7176/cer/12-12-01","url":null,"abstract":"FRP reinforced polymers are widely accepted for use in civil engineering applications to strengthen constructions and application of confinement on the concrete columns, thereby increasing their ductility and increasing their carrying capacity as these materials are characterized by high tensile strength, high strength-to-weight ratio and high corrosion resistance of FRP composites, etc. In addition, the exposure of reinforced concrete structures to fire is one of the most dangers challenges that lead to great destruction and failure the structural in addition to loss of life. With the development of computer simulation theories to study the behavior of elements and structures under the influence of different loads (static, dynamic, thermal, etc.), it is possible to study the behavior of concrete columns under the influence of axial vertical and non-axial structural loads, and compare the results with previous research, thus saving time, effort and cost instead Of laboratory testing. Strengthening concrete columns with fiber-reinforced polymers (FRP) has been studied extensively, but the majority of published studies have focused on circular columns. Most concrete columns in the field have square or rectangular cross sections and resist eccentric loading as well. The objective of this study is to investigate the performance of square reinforced concrete (RC) columns, wrapped with carbon FRP subjected to fire so, in this paper, an analytical study was conducted using the ANSYS Workbench program, which follows the finite element method, to determine the effect of layers number of CFRP on carrying capacity of concrete columns and to know the effect of external standard fire on confined concrete columns with CFRP. The numerical results were compared with experimental results as far as possible, and revealed the accuracy of the analytical models, when compared to the experimental studies. The results shown that with increase the layer number of CFRP, the carrying capacity of concrete columns will increase, no benefit with increase the number of CFRP more than 4 layers where polymers materials are sensitive to fire so that it needs to insulation.","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75050966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of Malaria Risk Using GIS and Multi Criteria: The Case Study of East Gojjam Zone, Ethiopia","authors":"A. Mihiretie","doi":"10.7176/cer/12-12-03","DOIUrl":"https://doi.org/10.7176/cer/12-12-03","url":null,"abstract":"Malaria is one of the most severe public health problems worldwide with 300 to 500 million cases and about one million deaths reported to date, 90% of which were reported from Sub Saharan African countries like Ethiopia. The main objective of the study was Assessment of malaria risk areas by using the GIS-based MCA approaches in East Gojjam zone. Weighted overlay technique of multi-criteria analysis was used to develop the malaria risk map. The malaria risk map was produced depending upon the overlay analysis of the malaria hazard map and some factors like land use land cover, population density, health stations. The malaria risk map was classified into four suitability index such as very highly suitable, high suitable, moderately suitable, and low suitable. The result shows that around 21.02% areas is very highly suitable for malaria risk, 24.49% is high suitable, 24.66% is moderately suitable and 29.83 % is low suitable for malaria risk areas.","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"138 5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85539012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Rice Husk Ash on Sub-Grade Bearing Strength in Stabilization of Expansive Soils for Low Volume Roads in Kenya","authors":"Catherine Mugai, Benedette Sabuni, E. Neyole, Faith Mugai","doi":"10.7176/cer/12-11-04","DOIUrl":"https://doi.org/10.7176/cer/12-11-04","url":null,"abstract":"The cost of cement and lime used in stabilizing soils can be reduced by using locally available rice husk ash which is known to contain pozzolanic properties. This paper studies the variations in sub-grade bearing strength of clay when rice husk ash (RHA), lime and cement are added in varying proportions. Chemical analysis was first carried out to establish the silica content in the RHA. CBR test was conducted to establish the strength properties of the various soil mixes. RHA was used as the main stabilizing agent added at varying proportions of 0%, 5%, 10%, 15% and 20%. Lime and cement proportions were constant in each batch but varied across the six batches as 0%, 2% lime, 4% lime, 6% lime, 1.5% cement and 2% cement. The test results show that RHA in combination with lime can be used as an economic and eco friendly stabilizing agent giving a significant improvement in the sub-grade bearing strength of cotton soil. Keywords: key words, Rice Husk Ash (RHA), California Bearing Ratio (CBR), Sub-grade, Lime, Cement DOI: 10.7176/CER/12-11-04 Publication date: November 30 th 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90063162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of the Hydraulic Performance of the Drainage System in Dire Dawa Town","authors":"Moges Tariku","doi":"10.7176/cer/12-11-01","DOIUrl":"https://doi.org/10.7176/cer/12-11-01","url":null,"abstract":"The constructed drainage structure was expected to carry the design discharge which generated from the catchment area and dispose safely to the outlet points. The study has mainly focused to assessing current status of drainage system and evaluates the hydraulic performance of the drainage system. The rational methods have been used to calculate proposed discharge and HY-8 software used for culvert analysis. The current drainage status of the towns was poor, the road performance was reduced to deliver, the service life of the road reduced, and the cost for maintaining the road increased, the compression between the proposed and existed carrying capacity of drainage structures showed that the exist drainage structures are hydraulically insufficient. HY 8 result shows the existed culvert was hydraulically insufficient and 50-63.5% of the proposed peak discharge overtopped and flows on the road. Keywords: Poor drainage, Road performance, Hydraulic Performance DOI: 10.7176/CER/12-11-01 Publication date: November 30 th 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89711218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural Behavior of Reinforced Concrete Hybrid Wide Beams under Shear Effect","authors":"R. Abbas","doi":"10.7176/cer/12-11-05","DOIUrl":"https://doi.org/10.7176/cer/12-11-05","url":null,"abstract":"The present work contains experimental study for the structural performance of reinforced concrete wide beams made from two grades of concrete (32.6 and 63.7 MPa) subjected to shear effect. The specimens involve ten wide beams of dimensions 1200×220×110 mm. The wide beams were divided into two groups according (a/d) ratio, the first group are of (a/d) ratio (2.5) and the second group are of (a/d) ratio (3.5). The first wide beam in each group is normal strength concrete, the second sample is high strength concrete while the third beam is made from normal strength concrete at top and high strength concrete at bottom, the fourth sample is made from high strength concrete at top and normal strength concrete at bottom, the last beam is divided in to three sections, the mid section from normal strength concrete while the sides from high strength concrete. All the tested wide beams were reinforced with 4φ8mm longitudinal bars in bottom and 2φ5mm in top without web reinforcement. In both groups, comparing to first beam, the second beam exhibits greater ultimate load by about (42.8% and 41%) respectively, the third beam show increasing in ultimate load by (8.5% and 5.26%) while the fourth beam denote increasing in ultimate load by (19% and 15.8%), finally, the increasing in ultimate load of the fifth beam is about (33.3% and 32.6%). Wide beams made totally or partially from high strength concrete show larger deflection values than the reference beams. Crack width values at service and final stages were recorded. All the tested wide beams were failed in shear. Keywords: wide beams; shear effect; High Strength Concrete; hybrid beams. DOI: 10.7176/CER/12-11-05 Publication date: November 30 th 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82666524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pre-Scaling up of In Situ Moisture Conservation Techniques on Maize (Zea mays L.) yield in Dugda District","authors":"Dulo Husen","doi":"10.7176/cer/12-11-02","DOIUrl":"https://doi.org/10.7176/cer/12-11-02","url":null,"abstract":"The activity was conducted during 2019 cropping season in Dugda District of Tepho Choroke Kebele.  The objective was to scale up the selected in situ moisture conservation structures with maize crop (Tied ridge and furrow closed at both ends), improved farmers' knowledge and skills on application of improved technology through training and analyzed cost benefit of the structures. Five FREG groups were established in Tepho Choroke kebele of Dugda District. The total number FREG members were hold 30 male and 10 female farmers. A total of 130  farmers, 2 DAs, 4 SMS and 16 others were participated on the training respectively. The mean yield obtained from tied ridge and furrow closed at both ends were 99.41 and 86.74 kg ha -1 , respectively and sold 850 Birr Qt -1 at the current price. The net benefit obtained from tied ridge and furrow closed at both ends were 56,230 and 45,194 - Birr ha - 1 , respectively. This implied that, the profit obtained from tied ridge was much better than furrow closed at both ends. This structure is much better in increasing yield and crop residue of maize. In addition, the total estimated profit obtained from furrow closed at both end are much better than the usual farmers practice. This also implied that in situ moisture conservation structure ( tied ridge and furrow closed at both ends) are more economical and better if it is more scaled up in the study area and similar agro ecologies. Extension worker and Woreda Agricultural Bureau should have given attention to popularized and scaling up this technology to overcome problem of moisture deficit and food insecurity and improve agricultural production in the study area and similar agro ecologies. Keywords: FREG, Furrow closed at end, Moisture deficit, Net benefit, Tied ridge DOI: 10.7176/CER/12-11-02 Publication date: November 30 th 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":" 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91412348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of Climate Change Impact on Streamflow (A Case Study of Dabus River,Abay Basin Ethiopia) Using CORDEX-RCP and SWAT Model","authors":"Bernabas Tesfaye","doi":"10.7176/jees/10-11-04","DOIUrl":"https://doi.org/10.7176/jees/10-11-04","url":null,"abstract":"Climate change is becoming one of the most debating and threatening issues in terms of global context which alter regional hydrologic conditions and results in a variety of impacts on water resource systems. The aim of this study is to assess the impact of climate change on the stream flow of Dabus Sub-basin which located in upper Blue Nile Basin of Ethiopia. The CORDEX RCM downscaled and bias corrected were used for the climate projection.  To estimate the level of impact of climate change, climate change scenarios of precipitation and temperature were divided into three time windows of 25 years as the whole from (2025-2099). Soil and water assessment Tool (SWAT) was calibrated and validated for stream flow simulation using SWAT-CUP with a method of SUFI2. The results showed that the value of calibration and validation reveals a good agreement with R 2 =0.84 during calibration and R 2 =0.82 during validation whereas NSE= 0.75 during calibration and NSE=0.72 during validation. The maximum and minimum temperatures increase for the three time horizons under both scenarios with largest increase under RCP8.5.  The largest increase of mean annual maximum temperature under RCP4.5 is 1.31 o C while under RCP8.5 that increase by 3.097 o C in future periods of  (2075-2099). Similarly, The largest increase of  annual minimum temperature under RCP4.5 scenario by 1.28 o C while 1.42 o C under RCP8.5 in future periods of (2075-2099). Compared to the base line period the total annual precipitation decrease for the three time horizons under both scenarios. A decrease of mean annual precipitation under RCP4.5 are 12.8% , 18.26% and 21.27% while under RCP8.5, it show decrease by 13.76%, 14.87% and 13.6% in the future periods of (2025–2049), (2050-2074)and (2075-2099) respectively. The stream flow projections are made in the future with two emission scenarios of RCP4.5 and RCP8.5, the study show that an average annual decrease in the stream flow up to 11.97% for RCP4.5 and up to 13.37% for RCP8.5 in the next 75 years. Keywords : Dabus Sub basin; SWAT; RCP Scenario; CORDEX RCM ; Climate Change DOI: 10.7176/JEES/10-11-04 Publication date: November 30 th 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"331 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91458789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Removal of Arsenic from Paint Industries Wastewater by Chemically Modified Low Cost Adsorbent Derived from Sugar Cane Bagasse","authors":"M. A. Yalew","doi":"10.7176/cer/12-10-03","DOIUrl":"https://doi.org/10.7176/cer/12-10-03","url":null,"abstract":"Arsenic is one of the most toxic heavy metals to the environment which cause community health problem due to its high toxic nature. Several physiochemical techniques, such as adsorption, ion exchange, lime softening, reverse osmosis, coagulation and precipitation are used for arsenic removal but in this study, adsorption was used because of its simplicity to use and availability of a wide range of adsorbents. Adsorption is the process which is used for the removal of heavy metals from wastewater. Although there are Various adsorbents methods used to remove different type of heavy metal ions for study, iron impregnated activated carbon which was derived from sugarcane bagasse, was investigated as potential adsorbent for the removal of arsenic from aqueous solution. The synthetic wastewater was prepared in the laboratory to conduct the experiments. Batch experiments were conducted to obtain the optimum conditions for arsenic adsorption. Effect of experimental parameter such as pH, adsorbent dose, and initial arsenic ion concentration was determined at constant contact time of 30min and atmospheric temperature. The optimum conditions obtained were, pH 7, 1mg adsorbent dose and initial concentration of 20mg/L. Adsorption behavior could be described using the Langmuir and Freundlich isotherm models. Adsorption data was well fitted in Langmuir isotherm model. The maximum adsorption efficiency was found to be 96.5% at optimum experimental parameters of pH 7, adsorbent dose of 1g and initial arsenic concentration of 20mg/L. Keywords: Chemical activation, Carbonization, Impregnation, Activated Carbon, Adsorption, Settling, Filtration, Arsenic Removal DOI: 10.7176/CER/12-10-03 Publication date: October 31 st 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89890180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluations of Stream Flow Response to Land Use and Land Cover Changes in Wabe Watershed, Omo-Gibe Basin, Ethiopia","authors":"Y. Abose","doi":"10.7176/cer/12-10-02","DOIUrl":"https://doi.org/10.7176/cer/12-10-02","url":null,"abstract":"Land Use and Land Cover Change (LU/LC) is one of the notable human induced worldwide changes. Hence, understanding the stream flow responses of a watershed to this dynamic change is becoming fundamental for water resources management planning. The study was conducted with the objective to analyses the impact of Land use and Land cover changes on stream flow response of Wabe watershed, in Omo-Gibe basin. Land use and land cover maps were developed using satellite image of Landsat5 TM 1988, Landsat7 ETM+ 2001 and Landsat8 OLI/TIRS 2018 through maximum likelihood algorithm of supervised classification using ERDAS Imagine 2014 and ArcGIS software for satellite image processing and map preparation. A physical based, semi-distributed hydrological model SWAT was used to simulate LU/LC change effects on the stream flow responses of watershed. During the study period the land use and land cover has changed due to natural and anthropogenic activity. The results depicted that there was an incessant expansion of agricultural land, built-up area and forest cover, on the other hand declining of agroforestry; grassland and woodland were happened during from the 1988 to 2018 periods. Due to the occurred LU/LC changes, the mean monthly stream flow were increased by 5.97m 3 /s for wet season and similarly the dry season flow showed increasing by 0.96m 3 /s during the study periods from 1988 up to 2018. Generally the result indicated that large changes of the stream flow in the watershed. Hence result notified an urgent intervention, so as to regulate the LU/LC change and to reduce its strong impacts on the stream flow of the Wabe watershed. Keywords: Land use/Land covers, stream flow, Wabe watershed, SWAT Model DOI: 10.7176/CER/12-10-02 Publication date: October 31 st 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"60 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89059623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}