American Journal of Civil Engineering最新文献

{"title":"Evaluating the Effects of Watershed Characteristics on River Flow for the Case of Fetam River, Ethiopia","authors":"Solomon Bogale Aynalem, Megersa Gemechu Liben","doi":"10.11648/J.AJCE.20200806.12","DOIUrl":"https://doi.org/10.11648/J.AJCE.20200806.12","url":null,"abstract":"Evaluating the effects of watershed characteristics have impacted on the stream flow of the watershed by changing the magnitude of surface runoff and ground water flow. This study is mainly focusing the effects of watershed characteristics on the stream flow by changing SURQ and GWQ for the wet months (June, July, August) and dry months (January, February, March) through satellite Remote Sensing (RS) and Geographic Information System (GIS) integrated with the SWAT model, climate characteristics on stream flow, slope and rainfall effects on stream flow. ArcGIS used to generate land use and cover maps from Landsat TM and ETM+ acquired, respectively, in 1995, 2005 and 2015. The result of this analysis showed that the cultivated land has expanded during the study period of 1975-2002. Using the three generated land cover maps, three SWAT models set up were run to evaluate the effects of watershed characteristics on the stream flow of the study area. The performance of the SWAT model was evaluated through sensitivity analysis, calibration, and validation. Ten flow parameters were identified to be sensitive for the stream flow of the study area and used for model calibration. The model calibration was carried out using observed stream flow data from 1975 to 1993 and a validation period from 1993 to 2002. Both the calibration and validation results showed good match between measured and simulated stream flow data with the coefficient of determination (R2) of 0.89 and Nash-Sutcliffe efficiency (ENS) of 0.78 for the calibration, and R2 of 0.91 and ENS of 0.88 of the validation period. The result of this analysis indicated that the mean monthly stream flow increased by 21.92m3/s for the wet months while for the dry months decreased by 13.1 m3/s. Generally, the analysis indicated that flow during the wet months has increased, while the flow during the dry months decreased. The SURQ increased, while GWQ decreased from 1975 to 2002 due to the increment of cultivated lands. The model results showed that the stream flow characteristics changed due to the land cover changes during the study period.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"10 1","pages":"139"},"PeriodicalIF":0.0,"publicationDate":"2020-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84841937","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":"A Study on the Mechanical Properties of the Hybrid Fiber-Reinforced Mortar Using the Macro Steel and Micro Carbon Fibers","authors":"Gwang-Hee Heo, Jong-Gun Park, Hyung-Min Jun, Dong-Ju Seo, Sung-Gon Koh","doi":"10.11648/J.AJCE.20200806.11","DOIUrl":"https://doi.org/10.11648/J.AJCE.20200806.11","url":null,"abstract":"In the present study, an experiment was conducted to investigate the mechanical properties such as fluidity, compressive strength and flexural performance (flexural strength and toughness) of a single fiber-reinforced mortar (FRM) using only macro steel fiber (SF) or micro carbon fiber (CF) with different material properties and SF-CF hybrid FRM using a mixture of macro SF and micro CF. The specimens incorporated macro SF and micro CF in the mix proportions of 100-0%, 75-25%, 50-50%, 25-75% and 0-100% by volume at a total fiber volume fraction of 1.0%. Their mechanical properties were further compared and reviewed with the plain mortar at 28 days of age. The experimental results of fresh mortar showed that the table flow of mortar using only macro SF was slightly reduced compared to plain mortar, whereas the table flow of mortar using only micro CF and SF-CF hybrid mortar decreased significantly with increase of micro CF. It was revealed from the test of the hardened mortar that the SF-CF=75-25% (M3) specimen showed the highest compressive and flexural strength, and the SF-CF=50-50% (M6) specimen obtained the highest flexural toughness. Therefore, it was possible to confirm the synergistic reinforcement effect of that enhanced the strength and improved the flexural performance by hybrid of macro SF and micro CF. Based on the results of this experiment, the optimal mix proportion of SF-CF hybrid FRM is proposed in this paper to improve the compressive strength, flexural strength and flexural toughness.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"16 1","pages":"128"},"PeriodicalIF":0.0,"publicationDate":"2020-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85876302","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":"An Investigation on Coffee Thread Blight Caused by Corticium koleroga (Cke) Hoehnel and Its Associated Factors in Southwest Ethiopia","authors":"Nagassa Dechassa, A. Chala, K. Belachew, E. Shikur","doi":"10.11648/J.JDDMC.20200603.11","DOIUrl":"https://doi.org/10.11648/J.JDDMC.20200603.11","url":null,"abstract":"Thread blight caused by Corticium koleroga is a devastating disease that causes severe damage to C. arabica in south-western Ethiopia. However, it is one of the least researched diseases in Ethiopia. Therefore, the current work was designed with the objectives to assess the incidence and severity of the disease and identifying major factors associated with the disease intensity in south-western Ethiopia. For this purpose, field surveys were conducted on 180 farmers’ fields in 12 districts of major coffee growing areas in south-western Ethiopia during 2017 cropping season. The average thread blight incidence varied from 0% to 46% while mean disease severity ranged from 0% to 44%. The thread blight disease incidence and severity were higher at areas representing highland and midland altitudes compared with lowland altitudes. Thread blight severity was positively and strongly associated with rainfall (r=0.75) and relative humidity (r=0.85), but the disease severity was negatively and strongly associated with mean temperature (r=-0.79) and shade level (r=-0.50), while it was positively and intermediately correlated to altitude (r=0.44) and coffee production systems (r=0.36). The present study revealed the importance of coffee thread blight in south-western Ethiopia and identified factors associated with the disease intensity. Future research should be directed towards surveying more agro-ecologies to have a complete picture on the importance of thread blight disease across the country and to recommend disease management strategies.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"21 1","pages":"22"},"PeriodicalIF":0.0,"publicationDate":"2020-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78534525","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":"Inference on the Surveying Methods at the 8th Century in Japan","authors":"Kaoru Yoshida","doi":"10.11648/J.AJCE.20200805.11","DOIUrl":"https://doi.org/10.11648/J.AJCE.20200805.11","url":null,"abstract":"Ancient regional records on geography named Fudoki were compiled in Japan at the 8th century. There were about 60 provinces at that time, but only 5 Fudoki (transcripts) have remained at present. Among them, Izumo Fudoki (edited in 733) is not only almost complete, but also contains detailed geographic data (surveying data) not found in the others. The surveying data are distances between major points, heights and sizes of mountains, sizes of lakes and isles etc. However, there are many differences when comparing these surveying data with actual sites. The Fudoki researchers had tried many times to interpret the relationships between the two, but many unclear points have remained. During the time, we civil engineers had little interest in the Fudoki. In this paper, we estimated the surveying methods by comparing the Fudoki data with map data and confirming the sites, then obtained the following conclusions. The distances were almost correct, the heights of the mountains were converted using the number of steps, the perimeters of the mountains were calculated with the trails as diameters, and the sizes of the lakes and isles were the lengths of the waterways. The surveying methods at that time were simple, but the results obtained were practical. We think that these ancient surveying methods were widely used, not in one region or one period.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"1 1","pages":"106"},"PeriodicalIF":0.0,"publicationDate":"2020-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88276581","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":"Challenges Facing Local Contractors Working with Chinese Contractors in Addis Ababa Building Projects","authors":"Solomon Esaiyas, G. Kahssay","doi":"10.11648/J.AJCE.20200804.12","DOIUrl":"https://doi.org/10.11648/J.AJCE.20200804.12","url":null,"abstract":"Building construction projects particularly represents one of the largest sectors of the construction industry. Currently, the rise in construction of high rising buildings are observed in Addis Ababa, the capital city of Ethiopia. The number and size of building construction projects that are being constructed in the city are increasing through time and most of these projects were being carried out by Chinese contractors. Local contractors are also involved in those projects via a subcontracting strategy. However, it is not easy for local contractors to succeed by working with their foreign counterparts who have massive international experience and capacity. The aim of this study was assessing and identifying the challenging factors affecting local contractors’ performance in Chinese building projects in Addis Ababa. In order to achieve the objectives of this study, both quantitative and qualitative research approach were used with primary and secondary source of data. This study employed three types of data collection techniques such as a questionnaire surveys, interviews and observations. The target population for this study are local contractors and consultants involved in building projects that are carried out by Chinese contractors. In this study the researcher used Census/Parametric method of survey. That mean all target population of this study are included in this investigation, based on the consent and willingness of the participants. The Relative Importance Index (RII) was used as an instrument for analyzing data collected through questionnaire in tabular form by using Likert’s scale of five ordinal measures. Based on the analysis, it was found that the most challenging factors affecting local contractors’ performance in Chinese building projects were financial constraints, information exchange problems, cultural differences, unfamiliarity with Chinese work methodology and project complexity with a RII value of 0.84, 0.81, 0.77, 0.73 and 0.71 respectively. This study also identified and discussed the major cause and impact of those challenges and proposed measures to minimize their effect on the local performance in the upcoming projects through interviews from respondents and analyzed by using content analysis.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"9 1","pages":"87"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82210289","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":"Effectiveness of Joint Venture for Local Contractors in a Mega Project Construction","authors":"Dagninet Cherinet","doi":"10.11648/j.ajce.20200804.13","DOIUrl":"https://doi.org/10.11648/j.ajce.20200804.13","url":null,"abstract":"Mega Construction Projects are defined as a very large investment construction project, or aggregate of projects, characterized by magnified cost, extreme complexity, increased risk, lofty ideals, and high visibility, in a combination that represents a significant challenge to the stakeholders, a significant impact to the community and pushes the limit of construction experience. The main objective of this study was to assess effectiveness of joint venture for local contractor to construct a mega project construction. The specific objective of this study was to determine the effective way of formation and implementation procedure, to determine legal procedures and steps of joint venture between local contractors, to analyze different kinds of joint venture among local contractors and to analyze risk of joint venture among local contractors to construct a mega project construction. The study used both qualitative and quantitative research, and data collection method used was interview, close ended questionnaires’, different books, articles, and web sites. The study uses also purposive sampling technique. The study revealed that the most motivation factor and reason to form a Joint Venture in construction is to obtain technology transfer, the most selection criteria to select a construction JV partner is ability, experience and skills of JV partner and to succeed in JV performance a JV management should be strong. The study indicated that some of the articles form the commercial code explains about JV need an amendment. The study also indicates legal issues should be considering in Ethiopian commercial code to facilitate formation construction JV. This study also revealed the best JV type suitable for local contractors to establish domestic JV is a contractual JV type. Finally, the study shows that the most factors to create a problem in construction JV is unclear partner roles and the dominant risk factor associated with construction JV is partner parent company in financial problem. Also, the study came up with conclusion that the existing legal norm context about CJV should be revised with amendment of some of the articles from the existing commercial code of Ethiopia.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"3 1","pages":"97"},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87214871","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":"Analysis of Vegetation Effects on Slope Stability of Embankment","authors":"M. Hasan, Mehejabin Chowdhury Ankan","doi":"10.11648/j.ajce.20200804.11","DOIUrl":"https://doi.org/10.11648/j.ajce.20200804.11","url":null,"abstract":"Embankments play a significant role in protecting cities from many natural disasters. Erosion and landslides of embankments and natural slopes are common phenomena occurring every year in Bangladesh. It has become a great concern of protecting embankments and natural slopes from failure. In many cases, traditional methods for protecting embankments and natural slopes are not effective during their designed lives. In such a condition, bio-engineering has been adopted in many countries as an effective and environment friendly measure for the protection of slopes. The role played by vegetation in improving slope stability is now well recognized. Many research works have been done in many countries on many species of trees that are locally available and suitable for the climatic and soil conditions of that country. In this study, an attempt has been made to evaluate the performance of lebbek tree and royal poincianain protecting the Rajshahi City Protection embankment. In-situ direct shear test was performed on block samples to determine the in-situ shear strength of rooted soil and soil without root. A numerical analysis has been performed to compute the factor of safety and shear strength of slope soil with root and without root. Also the effect of different types of vegetation on slope stability is observed by numerical analysis. It has been found that the values of factor of safety vary between 1.781 and 1.926 in case of slope without root whereas the values of factor of safety vary between 1.997 and 2.173 in case of slope with root. In numerical analysis, the shear strength of soil varies between 40.311 kPa to 41.782kPa in case of slope without root whereas in case of slope with root this value varies between 50.929 kPa to 52.13 kPa. The average percentage of increase in shear strength for lebbek tree root is 14.35% whereas this value for royal poinciana is 24.29%. It has been also found thatthe factor of safety of soil slopes without vegetation, with uniform vegetation, cylindrical vegetation and semi-spherical vegetation are 1.605, 1.653, 1.654 and 1.616 respectively. From the results, it is understood that plants with cylindrical root architecture increase the most significantly slope stability. It also appears that lebbek tree and royal poinciana may be low-cost and environment friendly alternative solution for the protection of embankment in Bangladesh.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"1 1","pages":"77"},"PeriodicalIF":0.0,"publicationDate":"2020-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89129419","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":"Study of Characteristics of Bricks Produced in Kathmandu, Nepal","authors":"S. Subedi","doi":"10.11648/j.ajce.20200803.13","DOIUrl":"https://doi.org/10.11648/j.ajce.20200803.13","url":null,"abstract":"The quality of brick is determined by its physical, mechanical and microstructure characteristics. The main objective of this study was to assess the characteristics of different types of bricks produced under various clay composition, different types of kiln used, and various firing temperature, and cooling process, which are considered as the major factors affecting the brick quality. A mixed-method approach was used to carry out this study. Both primary and secondary data were collected form field observations, discussions, lab experiments, and literature review. Literature review was done to identify the relationship between affecting factors and brick characteristics. The status of bricks produced was assessed through lab tests. The results from both methods were compared and discussed thoroughly. The purposive sampling method was adopted to collect brick samples from six different brick factories situated in Kathmandu and lab tests were carried out in the Engineering Material Lab at Institute of Engineering (IOE) Pulchowk Campus, Lalitpur, Nepal. Deformation, bulk density, water absorption capacity, and compressive strengths of sampled bricks were observed and then compared with standard code values as well as with previous findings. The study showed that none of the brick samples was found within the standard benchmarks, and the bulk density was low, however, the water absorption capacity and compressive strength values of all the sampled bricks were found to be within the allowable limit, even though they were close to the lower bound. The study also discussed technical, social and environment policy related issues that are important for producing and making the best use of quality bricks. The study results may be applied to other places where similar situation exists.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"93 1","pages":"64"},"PeriodicalIF":0.0,"publicationDate":"2020-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80463791","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":"Waste Rubber Tires: A Partial Replacement for Coarse Aggregate in Concrete Floor Tile Production","authors":"Gemeda Etefa, Alemu Mosisa","doi":"10.11648/j.ajce.20200803.12","DOIUrl":"https://doi.org/10.11648/j.ajce.20200803.12","url":null,"abstract":"Concrete tile is one of the most used construction materials in the world. Cement and aggregate, which are the most important constituents used in concrete tile production, they are the vital materials needed for the construction industry. This led to a continuous and increasing demand of natural materials used for their production. Parallel to the need for the utilization of the natural resources emerges a growing concern for protecting the environment and a need to preserve natural resources (such as aggregate) by using alternative materials which are recycled or waste materials. In this research, a study was carried out on the use of used rubber tires as a partial replacement for coarse aggregates in concrete tile production using locally available waste tires. A review of relevant literatures was done to study previous works in the subject matter. The research was carried out by conducting tests on the raw materials to determine their properties and suitability for the experiment. Concrete mix designs are prepared using the DOE method and a total of 12 mixes were prepared consisting of two concrete grades (C25 and C30). The specimens were produced with percentage replacements of the coarse aggregate by 10, 20, 30, 40 and 50% of rubber aggregate with and without supper plasticizer (admixture). Moreover, a control mix with no replacement of the coarse aggregate was produced to make a comparative analysis. The prepared samples consist of concrete cubes, cylinders and beams. Laboratory tests were carried out on the prepared concrete samples. The lists of tests conducted are; material property, slump, unit weight, compressive strength, splitting tensile strength and flexural strength tests. The data collection was mainly based on the tests conducted on the prepared specimens in the laboratory. The test results were compared with the respective conventional concrete properties and show that there is a reduction in compressive strength of the concrete due to the inclusion of rubber aggregates. This is improved by using admixture to some extent, but lower density and enhanced ductility are the same, and there was a slight increase in flexural strength without admixture. The overall results show that it is possible to use recycled rubber tires in concrete tile production as a partial replacement for coarse aggregates. Nevertheless, the percentage of replacement should be limited to 10%.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"43 1","pages":"57"},"PeriodicalIF":0.0,"publicationDate":"2020-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84534975","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":"Sensitivity of Permafrost Adjacent to Bored Pile in Wetland Tundra During Concrete Hydration Heating","authors":"Ziying Liu, Tianlai Yu, Lipeng Gu, N. Yan, Hongxiang Zhang, Z. Piao","doi":"10.11648/J.AJCE.20200802.13","DOIUrl":"https://doi.org/10.11648/J.AJCE.20200802.13","url":null,"abstract":"The permafrost in wetland area is very sensitive to temperature change due to its special geological conditions. By observing the temperature data of the pile-soil junction of the bored concrete pile, as well as measuring the geotechnical parameters and thermophysical parameters of the soil around the pile, it statistically analyzes the significant correlation factors related to the time when the temperature of the pile-soil junction rises to the peak, including the dry density and liquid index of the frozen soil. The formula for calculating peak time is summarized and the fitting effect is compared. The results show that peak time is positively correlated with dry density and obeys cubic curve. It is negatively correlated with the liquid index and follows the growth function curve. The peak time was not significantly correlated with the buried depth of the temperature sensor, peak temperature corresponding to the peak time, natural ground temperature, original temperature of pile wall, soil thermal conductivity, volume heat capacity, natural moisture content and plasticity index of frozen soil. The influence of concrete ratio on peak time is significant, and its correction coefficient follows S-shaped curve.","PeriodicalId":7606,"journal":{"name":"American Journal of Civil Engineering","volume":"53 1","pages":"37"},"PeriodicalIF":0.0,"publicationDate":"2020-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80741464","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}