Civil Engineering
Permanent URI for this collectionhttps://etd.hu.edu.et/handle/123456789/675
Browse
55 results
Search Results
Item PERFORMANCE OF HOLLOW CONCRETE BLOCKS WITH CRUSHED WASTE GLASS AS PARTIAL REPLACEMENT OF FINE AGGREGATE(Hawassa University, 2020-10-23) YOSEF KUMA AYANAConstruction is booming in developing countries like Ethiopia. As construction is increasing, demand and price of the construction materials are increasing. Among building construction components hollow concrete block is being widely used. From concrete block making materials fine aggregate is higher constituent. The uses of river sand as fine aggregate leads to exploitation of natural resources and also environmental concerns related to the disposal of various waste materials have escalated to a worrying level, among those: crushed wastes glass is one of them. Therefore, to make the construction industry sustainable, the use of waste materials in place of natural resources is one of the recommended. The main objectives of this study was to investigate the performance of class C hollow concrete blocks with crushed waste glass as partial replacement of fine aggregate and to determine the replacement percentages at which crushed waste glass can be effectively put into service and also compare the cost of crushed waste glass partially replaced in hollow concrete block with the conventional ones. The method used was experimental study. The crushed waste glass partial replaced fine aggregate with 10%, 20% and 30% by volume and the control mix was prepared. The compressive strength test was carried out at the 7th, 14th and 28th days, whereas the density and water absorption tests were carried out on the 28th day. As per the finding, the control mix compared with the replacement specimen, the density is decreased as the proportion of crushed waste glass increases and decreases by 5.6% at a 30% replacement, the water absorption decreases as crushed waste glass content increases and it decreased by 2.5% at a 30% replacement, the compressive strength with up to 20% replacement increases by 59.72%, but after that, it starts decreasing for 30% replacement by 10.64%, results showed that replacement of 20% fine aggregate by crushed waste glass was found to have optimal compressive strength, and also the production of block using 20% crushed waste glass saves cost compared to the conventional once by 2.06% in 1m2 area.Item EVALUTION OF THE CONTRIBUTION OF GEOMETRIC DESIGN OF THE ROAD INTERSECTION IN ALLEVIATING TRAFFIC ACCIDENT IN SHASHEMENE TOWN(Hawassa University, 2020-08-18) YASIN ASSEFA MOSSAEfficiency of intersections contributes significantly towards the efficiency of urban road networks. Whereas intersections constitute a very small part of the entire transportation network, more than 50% of all motor vehicle accidents occur at intersections. Because of the overrepresentation of intersection-accidents, intersections require special attention in the planning and designing of road networks. Thus, the main aim of this research study is the evaluation of the contribution of geometric design of the road intersections in alleviating traffic accident in the Shashemene town. Abosto and Kudus Mikael signalized intersections while Tekliye, Semaniyaand (81), arada Sefer, Gibrna, Zero Amst (05) and Mobile non signalized intersections were chosen for this thesis. These intersections were selected for the study from different locations within the town. They have more traffic accident than any other similar junctions do in Shashemene town. The geometric, traffic and accident data were collected during the morning and afternoon peak time periods using site observation, field measurement and video camera in each of the selected junctions. The study use four distinct scientific principles namely: accident frequency, accident rate, empirical Bayesian and critical accident method to identify black spot locations at selected intersections. Out of the methods, empirical Bayesian proved superiority so that much of the conclusion was based on this method. Log linear Poisson regression and Negative binomial regression model was used to investigate the effect of road geometric design elements on the road crash occurrence in the selected junctions.The results of paper proved that road junction Semaniyand, Tekliye, Kudus Mikael and Abosto were highly prone to accidents than other road junctions in Shashemene town with adjusted accident frequency values of 27.85, 26.54, 25.25 and 22.65 respectively. And also the result of this study shows, there is a strong correlation between road geometric design elements and road crash occurrence. The modeling result indicated that the explanatory variables such as lane width, super elevation, gradient, and intersection sight distance, shoulder width, median type, and median width, angle of intersection, side walk width and curves radius had significant effects on the occurrence of road traffic crashesItem PERFORMANCE EVALUATION OF OFF-STREET PARKING IN ADDIS ABABA CITY (A CASE STUDY IN SELECTED CENTRAL BUSINESS DISTRICTS)(Hawassa University, 2020-10-21) ALEMSEGED ESHETE TEKLEWOLDCar-parking sector has always been of great importance in terms of urban mobility, since it is a fundamental element in achieving a high level of accessibility in the city centers. Central Business Districts (CBD) are areas of dense traffic which result in parking problems. Addis Ababa, the administrative and financial capital of Ethiopia, is experiencing continued growth and change. But due to the fact that more than 60% of the vehicles in the country are operated in this city, parking problem is crucial. Parking plays an important role in mobility, access and the economic development of Addis Ababa. The space that parking requires can be problematic in any city, but it poses particular problem in Central Business Districts (CBD). Due to the absence of clearly designated areas of parking in Ethiopia, shortage of parking facilities has been a long standing problem in the country. Especially cities with greater economic activities, greatly faced to traffic congestion and delay problems. The general objective of this research is to evaluate the efficiency of off-street car parking in the Central Business District area of Addis Ababa City. Depending upon their greater demand requirement for a parking facilities, three central business districts of the capital (i.e. ‘Megenagna’, ‘Bole’ and ‘Merkato’) were chosen for detailed analysis. From the stated locations; 11, 13 and 11 off-street parking sites were selected for further analysis respectively. For data collection in and out data collection technique were used. Data was collected from May to September 2019 during the interval of time 8 am-6 pm. From the accumulation graph, peak hour for the demand was selected. The performance analysis result shows that off-street parking’s in the central business district of the city is over their capacity. Demand study was also made to ‘Megenagna’ site by using land use analysis method. From the demand analysis 2,454 additional parking spaces were required to afford the existing demand. In addition to this, structured interview was made to the users of the parking facilities to strengthen the analysis. The research conclude that the main problem of parking in the areas is lack of enough off-street parking space supplies, lack of parking policy and management system, absence of parking signs and marks which results in confusion for finding available parking spaces and lack of knowledge of users for parking usage and shared parking strategiesItem SEISMIC PERFORMANCE EVALUATION OF REINFORCED HCB FULLY GROUTED MASONRY WALLS AND ITS PERFORMANCE COMPARING WITH UNREINFORCED FULLY GROUTED MASONRY WALLS(Hawassa University, 2021-10-22) ZERIHUN TALE BIZUNEHA reinforced hollow concrete block masonry walls constructed by assembling masonry units, and it was the key structural element widely used to resist lateral loads in masonry buildings. Unreinforced hollow concrete block Masonry wall rapidly fails because of lateral load like an earthquake. Hence this study attempts to evaluate responses of a reinforced and unreinforced fully grouted hollow concrete block masonry wall, select the best walls based on differing their aspect (H/L) ratio, horizontal and vertical reinforcement ratio, and spacing. Also, know the behavior of reinforced and unreinforced fully grouted hollow concrete block masonry wall under lateral load and determine its percentage effectiveness. The study was conducted using finite element ABAQUS software for which a total of 24 masonry wall models were considered. For validation of the finite element method, reinforced masonry walls experimentally worked by M. Hany (2016), and the experimental results compared with the numerically modeled. The comparison of the results indicated that both experimental and numerical results agreed very well. After the validation, the effect of seismic load on reinforced and unreinforced fully grouted hollow concrete block masonry walls investigated by the quasi-static method. The comparison for ultimate load carrying capacity, stiffness degradation, and displacement ductility of each investigation parameter are carried out from the comparative analysis. It was found that the aspect ratio 1.39 wall vertical reinforcement ratio increases from 0.26% to 0.36%, the ultimate strength increase by 15.344% for push and 14.578% for pull direction. And also, the vertical reinforcement spacing increases the Ultimate strength of the wall decrease. The Ultimate shear resistance of the wall is reduced by 17.21% for push and 14.25% for pull direction for in-plane load when the spacing of Ø16 vertical reinforcement increases from 200mm to 400mm. The aspect H/L ratio increase from 1.39 to 1.95 the ultimate strength decrease by 38.15% for push direction and 41.89% for pull direction. Generally, aspect ratio, vertical reinforcement spacing, and vertical reinforcement ratio variation highly influence hollow concrete masonry wall seismic performance relative to horizontal reinforcementItem PRIORITIZATION AND ASSIGNMENT OF OPTIMAL MAINTENANCE STRATEGY OF PAVED ROAD SEGMENTS BY USING HDM-4 TOOL (A CASE STUDY IN SODO DISTRICT OF THE ETHIOPIAN ROADS AUTHORITY(Hawassa University, 2020-08-17) TSEGAWU WORKU KERCHOEfficient Pavement management maintenance system are backbone for an optimal maintenance strategies. Currently, 36% of the road segments under Sodo road network maintenance district (RNMD) are also in poor condition of performance. The poor state of the road network is caused mainly because of not applying timely and optimal maintenance. In addition to this, in countries like Ethiopia, a yearly limited budget is insufficient to maintain all deteriorated roads in the country.To counteract this problems, this study was aimed at setting prioritization and assignment of optimal maintenance strategy for 10 paved road segments of 690Km under Sodo RNMD by using highway development and management tool (HDM-4). To meet this objective pertinent data were collected from Sodo RNMD and many offices. Then, the collected data under different input type were entered manually into the HDM-4 software to make it ready for economic analysis. Four types of maintenance alternatives with different types of maintenance standards and intervention levels were used in this study for comparison of alternatives. After HDM-4 project analyses were carried, among the alternatives, an alternative with a higher value of net present value per cost (NPV/C) was considered as an optimal maintenance alternative for each road segment. Among the maintenance alternatives alternative two (Routine + SBST + 50mm asphalt concrete overlay) has generated a higher value of NPV/c than other alternatives and were considered as an optimal maintenance alternative for 5 road segments. Finally, the prioritization of segments for annual maintenance according to profitability was done by comparing the internal rate of return (IRR) values of each segment with an optimal alternative. In this regard, the Alaba to Sodo road segment was found to be a project with the highest value of IRR= 393.6% and should be prioritized first for maintenance. The remaining segments were prioritized likewise based on their respective IRR values. So It was found that using HDM–4 analysis in the process of establishing road maintenance strategies will reduce lifetime cost and increase benefits and profitabilityItem CHALLENGES OF TECHNOLOGY TRANSFER IN CONSTRUCTION INDUSTRY: THE CASE OF PREFABRICATED ELEMENTS IN BUILDING CONSTRUCTION IN ADDIS ABABA CITY(Hawassa University, 2021-04-27) ASGELE KIDU GEBREHIWOTMany construction innovations incorporate technologies that have been transferred from one geographical area or discipline to another for the facing numerous difficulties in the industry. Technology Transfer (TT) is in the interest of many developing countries; however it is not pacing forward as its target. Many of developing countries set policy to transfer prefabricated construction technique, yet there was a problem on its succeeding. Technology transfer initiatives can be instrumental in solving a lot of challenges in building construction. Dynamic change is needed today to overcome new challenges in the construction industry. Adoption of prefabrication is one of the possible solutions to such problems. This paper assessed the challenges of transferring and expansion of prefabricated building construction techniques through both qualitative and quantitative research method. Besides, this study aims to evaluate the current status of prefabrication building transferring and adoption in Ethiopia and, identified the best channels of transferring and expanding the technology. An extensive literature review was conducted on this subject towards the understanding of TT and prefabricated building construction in developing countries. And, a set of questionnaire and semi-structured interview was used to collect the data. As well as two case studies was conducted. Mean index and RII method using SPSS, and Excel has been used to analyze the results. On this study the practice of prefabricated building technology in Ethiopia shows almost to non-existence. As numerous challenging factors are impeding the adoption, and development of prefabricated technology in developing countries. The result shows, limited awareness and trust on the technology and shortage of initial funds are the most challenging factors in transferring and expanding of prefabricated building technology in Ethiopia. Shortage of infrastructure is also one of the critical obstacle in expanding the technology. Furthermore, as the succeeding of adopting and developing of one technology was measure through the mechanism used to adapt and improve the technology. Hence the study shows trainings was the best way to transfer and sustain prefabricated technology. As well as sub-contracting was the second best way in transferring and sustaining the technology. Other critical channel to improve the technology was working in research and development.Item STABILIZATION OF LATERITIC GRAVEL USING PRECIPITATED CALCIUM CARBONATE FOR THE USE OF SUBBASE CONSTRUCTION FOR LOW VOLUME ROADS: A CASE STUDY OF BATU TOWN(Hawassa University, 2021-10-26) FEYYISA GOBENA KUMBILateritic gravel materials do not satisfy the gradation requirement for subbase course as it is mostly composed of larger grain sized particles lacking of fine materials. The two most important factors likely to affect the engineering behavior of lateritic gravel materials were the gradation and the strength of the gravel particles which not satisfied by materials they are using at the moment. This thesis study has been done to check the use of blended precipitated calcium carbonate with lateritic gravel as subbase material for the construction of low volume roads in Batu town based on Ethiopia Roads Authority standard requirements for subbase materials. In the beginning engineering properties of both materials were studied by doing some laboratory tests on each materials differently and later the mechanical stabilization of lateritic gavel was carried out in blending of lateritic gravel with different proportion of Precipitated calcium carbonate. The optimum amount of precipitated calcium carbonate required for stabilization is obtained after the compaction test, as a result the maximum dry density attained was found to be 2.1g/cc after the blending of 30 percent precipitated calcium carbonate with 70 percent lateritic gravel. As the test result revealed the California bearing ratio values of blended materials were 42% which is more than Ethiopia Roads Authority specification requirement for low volume roads subbase. In addition to the improvement of California bearing ratio values the blending of precipitated calcium carbonate with lateritic gravel results in fulfill the Ethiopia Roads Authority specification requirement for gradation as it constitutes fine particles. The correlation of soaked California bearing ratio value and other independent variables like maximum dry density and optimum moisture content developed using Minitab statistical software to be Soaked California bearing ratio = -7.86 + 29.24 maximum dry density – 0.17 optimum moisture content. In conclusion the test results favors the use of blended Precipitated calcium carbonate and lateritic gravel as subbase material for low volume roads that can results in reduced cost road construction, reduced environmental problem caused by Precipitated calcium carbonate on children, improved California bearing ratio value and urban land use.Item CONTRACTORS’ CASH FLOW MANAGEMENT PRACTICES IN HAWASSA CITY(Hawassa University, 2020-07-25) TESHOME DEBESA NARAMOContractors follow certain procedures to manage income (inflows), expenditures (outflows), and deficits in their projects. Effective management of these components is essential to the survival and continual improvement of the competitiveness of construction companies and successfulness of the construction projects. However, in Ethiopia, management of these components of the cash flow exhibits performance shortfalls. The financial management practices of contactors in South Nations Nationalities People’s Regional State are poor and ineffective, and cash flow problems are problems of most contractors at different grade levels. Improving the performance needs understanding the practice and identifying the problems. It is in this light that, this study focuses on three specific objectives: assessing the current cash flow management practices of contractors, identification of causes of contractors’ poor cash flow management practices and the level of impact of contractors’ poor cash flow management practices on construction project performance in terms of cost and time. These objectives were achieved through quantitative and qualitative analysis of primary data; questionnaire survey and interview. Initially, different relevant literature were reviewed in depth in order to understand the practice and identify the variables for the questionnaire to address the objectives. The findings indicate that the cash flow management practices of the prime contractors are generally poor. The identified critical causes of these poor practices are lack of skill to manage cash flow, using payments for other purposes (not for the intended project purposes), poor project cash flow analysis, contractors’ dependency only on the client’s payments, poor project cash flow forecasting, and poor cash flow management strategies. These all causes have high negative impact on project time and cost performances.Item ASSESSMENT ON PROCUREMENT PROCESS AND EVALUATION CRITERIA SETTING PRACTICES IN BUILDING CONSTRUCTION: THE CASE OF SELECTED SNNPR BUILDING PROJECTS(Hawassa University, 2020-10-19) TAMIRAT ASHURO BETAMOThe procurement process for building construction work starts from procurement planning and then follows preparation of tender document, advertising the tender, submission of bids by the tenderers, evaluation of the submitting tender and award of the contract. This study assessed procurement process and tender evaluation criteria setting practices in selected SNNPR governmental building projects. The study were conducted on selected SNNPR governmental building projects by which their tender floated for grade BC-5/GC-5 and above contractors for building construction works for the last five fiscal years at selected level or “Ferji” (I) One 4 (four) zones. The result of the study indicates that 76.56% of participants agreed that technical qualifications, competence, and experience requirement of the bidder during bidding document were prepared by respective professionals but 60.94% participants agreed that there was no review of prepared technical requirements criteria’s and documents by second party professionals before tender floating. General & specific work experience and professional qualifications requirement with respect of minimum requirement from participants 60.93% for general & specific work experience and 62.5% for professional qualifications requirement of them agreed that the request was more than the projects minimum requirement stated at directives. Under financial criteria financial resource and annual turnover requirements did not aligned to the project demand. 67.19% of respondents agreed that equipment request was more than the projects minimum requirement and bidders were restricted not to propose leased or rented equipment for the project implementation. 54.69% of respondents agreed that current open NCB system in SNNPR governmental building project gives equal chance to participate at bid for all eligible bidders and 64.06% of them also agreed that contractors awarded as lowest responsive bid selected on this system are not effective at their project implementation. Procurement plan have been given lower attention at SNNPR governmental building projects during the overall procurement process. The study identifies that the most and common challenges and problems during procurement process and evaluation criteria setting at SNNPR governmental building projects for construction parties were unfair selective restriction and setting subjective criterions, inappropriate procurement plan in procurement processes and forgery document preparation and submission by contractorsItem RETROFITING OF REINFORCED CONCRETE COLUMNS USING COMPOSITE JACKETING(Hawassa University, 2020-04-15) SIMRET BERHEColumns are important cause for the stability of a constructed building, which are widely used in building frames and carries compressive loads. The purpose of Reinforced Concrete (RC) columns jacketing in this study is retrofitting of existing columns with poor structural performance and increase their strength and ductility. The methodology used is modeling and simulation for predicting performance in the real world. Simulation and modeling is used to understand whether under what condition and in which way a part will fail and what loads it can withstand. In this research work, it is found that the strength and cross section of the overlay concrete has significant effect on the capacity of axially loaded reinforced concrete composite jacketed columns. For C30, C50 and C70 concrete grade in the core the axial capacity of the jacketed column is enhanced by 3-10%. On the other hand, using different thickness and the same concrete grade considered, the axial capacity of the reinforced concrete jacketed column is 50-56% higher than axial capacity of the old concrete section. Similarly, for same grade of concrete of C30, C50 and different cross section the change in the capacity of the reinforced concrete composite jacketed axial columns became 148.3% and 161.6% of the core section respectively. It is also found that, the capacity of reinforced concrete composite jacketed axial columns is slightly affected by the variation loadings (eccentricity effect). Experimental model is used to calibrate the interface properties and material models in ABAQUS