Civil Engineering

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Assessment of causes of delay on selected asphalt road Projects in the Southern Region of Ethiopi
(Hawassa University, 2017-10-18) Mengistu G/kirosGesesew
Effect of Cow Dung, Cement and Fiber on Earthen Brick
(Hawassa University, 2018-10-13) Aster Memiru
Now days demand for housing is increasing because of fast population growth. To fulfill this need it is better to search for alternative construction materials, which are economically affordable. Earth is one of the potential construction materials, which can fill this gap. Earth housing is the most common housing used around the world. In Ethiopia, the “cob” type of housing method is the most common one. This research focuses on Adobe blocks that constructed from earth material. The aim of this research is to study the effect of cement, fiber and cow dung on the property (compressive strength and water resistance) of adobe block. Types of stabilizer used are Enset fiber, cement and cow dung. The amount of stabilizer used for this study is 0.2, 0.4 and 0.6% for Enset fiber, 2, 4 and 6% for cement and 5, 10 and 15% for cow dung of the dry mass of the soil. The result of this research indicate that both type and amount of stabilizer (cement, fiber and Cow dung) used affect the property of Adobe block produced. Comparison between the effects of Enset fiber and chid fiber on compressive strength and water resistance of Adobe block is also studied and also their property at failure. The results indicate that blocks stabilized with Enset fiber performed well under compression load and water when soaked. The optimum amount of fiber for compressive strength and water resistance is also determined. The other important finding in this research is the positive effect of cow dung on Adobe block. Loss of material, water absorption and loss of strength after soaking of adobe block stabilized with Cow dung is very less than block stabilized with cement or fiber. Therefore, cow dung significantly improves durability of block. Generally, from this research it can be concluded that well stabilized Adobe block can serve as potential construction material
ASSESSMENT OF PROJECT PERFORMANCE: CASE OF 40/60 SAVING HOUSE DEVELOPMENT ENTERPRISE IN ADDIS ABABA BOLE AYAT LOT II
(Hawassa University, 2018-10-22) ALIYA ABDOSH IBRAHIM
Construction industry has complexity in its nature because it contains large number of parties as clients, contractors, consultants and other stakeholders. Construction projects suffer from many problems and complex issues in performance such as cost, time and quality. The aim of this thesis is to identify and evaluate the main factors affecting the performance of construction projects in the case of Bole Ayat 40/60 condominium. Literature reviews about performance were sited to identify the factors affecting the performance of construction projects. The methodology/research design followed was descriptive research. A questionnaire survey was conducted and 44 factors were identified, categorized, evaluated and ranked from small and micro enterprises, client, consultants and contractors perspectives. The results were analyzed and discussed to obtain the most performance indicators. The relative importance index (RII) method was used here to determine perceptions of the relative importance of the performance indicators in construction projects. The extremely significant factors affecting time performance were shortage of material, financial problem and poor communication and coordination with RII 0.75, 0.74 and 0.71 respectively. Whereas the factors affecting cost performance were fluctuation in the cost of material, lack of cost planning and design change with RII 0.77, 0.693 and 0.691 respectively and factors affecting quality performance were educated and experienced personnel, quality of materials and equipment used in the project with RII 0.81, 0.72 and 0.69 respectively. Recommendations were formulated to improve performance of construction projects. It was concluded that every party participating on the project should have good communication and coordination to avoid design discrepancies and disputes to improve performance; they should have to hire qualified personnel to overcome any technical and managerial problems
SURFACE IRRIGATION POTENTIAL ASSESSMENT OF BONKOKA RIVER CATCHMENT FOR IRRIGATION SCHEME DEVELOPMENT IN DARA WOREDA, SIDAMA ZONE SOUTHERN REGION
(Hawassa University, 2019-03-12) ABRAHAM AMENU ANEBO
Surface irrigation potential assessment is very important for maximizing agricultural production by using surface irrigation method. The objective of this study was to assess surface irrigation potential of Bonkoka river catchment for surface irrigation schemes development in Dara Woreda, Sidama Zone Southern Nation Nationalities Peoples’ Regional State. Surface water irrigation potential assessment was undertaken by using ARCGIS10.3 software application, by using soil data, land slope data and land cover or land use data of study area were used in order to identify suitability of river catchment with respect to soil, land slope, land use or land cover and overlay analysis of soil suitability, slope suitability and land use or land cover suitability were undertaken. And also un-gauge Bonkoka River surface water potential discharge were estimated by using runoff coefficient of gauged Kolla river catchment which had similar soil type, land slope and land use or land cover. Water requirement of crops in the study area was estimated by using Cropwat8.0 software application and the Cropwat8.0 software estimates Reference Evapo-transpiration on monthly basis, Crop Evapo-transpiration, Potential Evapo-transpiration, Crop water requirement. Surface irrigation land suitability analysis result with respect to soil show that 100% of soil (covering an area 2,186 ha) are suitable and suitability analysis result with respect to slope 9% of slope in the study area (covering area 198.52 ha) are in the range of highly suitable to marginal suitable for surface irrigation application. Considering suitability analysis result with respect land cover or land use, land covered by agroforestry covering 28% or 606 ha area and 59% cultivated land (covering area 1,300ha) and remaining 13% grass land (covering area 280 ha) are suitable for surface irrigation application. From overlay analysis of suitability of surface irrigation with respect to soil, slope and land cover or land use result show that 31% of Bonkoka catchment (covering area 676ha) is suitable for surface irrigation.
MODELING LEVEL CROSSINGS’ TRAVEL TIME AND DELAY CHARACTERISTICS OF ADDIS ABABA LIGHT RAIL TRANSIT (AA-LRT)
(Hawassa University, 2019-04-17) DARIC TESFAYE
Traffic modeling is simplified representation of a part of traffic reality that provides a better understanding and interpreting of the complex traffic interactions. The objectives of this study is modeling level crossings travel time and delay characteristics of Addis Ababa light rail transit (AA-LRT) using simulation and mathematical models and evaluate the operational characteristics of the level crossings. In the process of achieving the objectives, the study investigate about peak period vehicle volumes, compositions, routings, LRV arriving frequency ,speed and the delays experienced. To meet the objective of this research intersection geometry data from field and traffic flow data at selected intersections is done by video recording and manual counting. In addition travel time data using light rail transit and minibus taxi is collected by traveling using these modes to a statistical number of repetitions. Suitable data inputs in forms of traffic volume, vehicle composition, vehicle routing, speed, train headway, travel time and delay at different incidences including level crossings are prepared. These suitable data inputs are introduced into VISSIM and SPSS analysis soft wares. Finally, the results were interpreted and the key research findings were presented in two types; i.e. through VISSIM simulation and SPSS statistical models. At the CMC level crossing the baseline without LRT scenario the average delay of traffic is 134.62s/veh ,the actual scenario with 00:05:41 LRV headway the average delay of traffic is 135.2 s/veh the delay increased by 0.43% and twice arrival frequency scenario the delay is 136.22s/veh with an increase in delay of 0.76% from the actual conditions. At the Sebategna level crossing the baseline without LRT scenario the average delay of traffic is 22.31s/veh ,the actual scenario with 00:06:30 LRV headway the average delay of traffic is 23.53 s/veh the delay increased by 5.47% and twice arrival frequency scenario the delay is 33.11s/veh with an increase in delay of 40.7% from the actual conditions. Additionally as observed in the mathematical model equation, the train’s travel time is dependent on running time, delay at grade intersection, open door close door time, close door start movement time and stop open door time in descending order. It is concluded that the average additional delays at level crossings increase from the base scenario and with increasing light rail crossing frequencies. In addition, delay at the level crossing is the second important variable that contributes for the variability of train travel time at peak hours.
EVALUATION OF HORIZONTAL ALIGNMENT DESIGN CONSISTENCY FOR TWO – LANE RURAL HIGHWAY: A CASE STUDY ALONG SHASHEMENE - WOLAYTA SODO AND SHASHEMENE - ASELA ROAD SEGMENTS
(Hawassa University, 2019-10-10) ALEMAYEHU AYELE
Design consistency is the conformance of highway’s geometric and operational features with driver’s expectancy. Techniques to evaluate consistency of a design are change in operating speed and change of vehicle stability along the horizontal alignment. To use operating speed and vehicle stability as the consistency tools requires the ability to accurately predict speed as a function of the horizontal roadway geometry. The current Ethiopian road Authority geometric design manual is based on design speed. However, due to the constraints resulting from roadway elements, right of way, and environmental features, inconsistency in operating speed based and vehicle stability based cannot be guaranteed. In order to make informed decisions to ensure highway geometric design consistency, the consistency evaluation of horizontal geometric design of operating speed and vehicle stability on simple curve and tangent section was studied. Forty five sections for both of horizontal curve and tangent section were selected from Shashemene to Wolayta Sodo and Shashemene to Asela. Roadway geometric design variables were obtained from design documents and through field measurements. The speeds of passenger cars, buses, and trucks were measured on each curve and its approaching tangent, under dry day time condition. This study focused on two major issues, in evaluating the horizontal geometric design consistency of selected alignments and developing operating speed predicting models for selected section. Therefore, the results obtained from consistency evaluation of change operating speed between simple curve and tangent section shows that twenty sections were in poor conditions, between design speed and operating speed shows that nine section in simple curves and thirty one sections in tangents sections were in poor conditions. Whereas, consistency evaluation between changes of side friction assumed and side friction demanded shows that twenty seven section in horizontal curves were in poor condition. Finally, both two models were found for horizontal curves and tangents. Model found for horizontal curve and tangents were governed by the combination of grade, super elevation and tangent length. This study would provide information about the improvement design manual for the existing level of design inconsistency and to develop guidelines that designers can use to improve the geometric design consistency of roadway features on high-speed of two-lane rural highway road.
SKILLED LABOR PERFORMANCE ASSESSMENT ON SELECTED PUBLIC BUILDING CONSTRUCTION PROJECT OF SNNPRS
(Hawassa University, 2019-10-13) BIZUNESH BEKELE
Skilled labor force is one of the vital elements for the continuity and successful implementation of construction. This study explored the current status of skilled labor performance in building project of SNNPRS. The main approaches used in collecting information for the study were through a questionnaire survey, case study, interview and personal observations of some major construction sites of SNNPRS. Methodological triangulation and member checking bolstered the trustworthiness of those interpretations. The questionnaire survey was distributed to 114 respondents and a total of 105 responses were received and case studies of seven projects of three trades for each which are concrete, masonry and bar bending was taken. For the analysis of the data, statistical analysis by using SPSS software and descriptive statistics were employed. The finding of the research indicated that most trade not fulfills individual level performance criteria. The crew level performance for most projects with productivity performance ability ratio (PAR) was greater than one indicating that the studied crews’ productivity performance was low. The main factor which affect performance of skilled labor in the order of their rank were lack of follow up the work progress, cash flow and financial difficulties, Lack of Training for workers, Inadequate briefing, too much work load and absence of clear uniform standard to accept work. Skilled labor capability impacts the project objectives which are safety, quality, cost and schedule. Thus the researcher recommends possible ways to manage or reduce such factors. Periodic training should prepare in advance in order to improve skill performance and Project managers shall introduce performance management system at individual and crew level so as to have reliable planning and controlling system to manage their work. This study will contribute contractors which undertake construction projects and about ways of improving their current status of skilled labor.
ASSESSMENT OF TRAFFIC CONGESTION AND ITS IMPACT OVER SELECTED ROAD CORRIDOR IN ADDIS ABABA CITY
(Hawassa Inversity, 2019-10-19) DAWIT GETACHEW ERGA
Traffic congestion problem is becoming a common problem in most developing countries of world. This study was conducted with an objective making assessment of traffic congestion and its impact over the selected road corridor in Addis Ababa City. Through reconnaissance survey the corridor from ‘Awutobis Tera’ Bus station to ‘Lamberet Menahereya’ in Addis Ababa city was identified and for analysis purpose the corridor was divided into three sections. The study was conducted starting from June up to October, 2019. Both quantitative and qualitative approach were used. 384 samples were used to conduct questionnaire survey for traffic congestion cause analysis. Out of this 32.5% of the required sample were drawn from section A, 27% from section B and the rest 40.5% was from section C. For making analysis on the performance level of road corridors and economic cost of traffic congestion, traffic volume, travel time delay, average travel speed and vehicle occupancy data were collected manually for a period of 12 hours a day at 15 minutes intervals on respective road corridors and for intersections the data were collected for two hours interval during rush periods. In addition to traffic condition data, the geometric data were also measured as part of the study. The analysis on causal factors for traffic congestion was conducted by SPSS software and analysis on level and economic cost of traffic congestion of the selected road corridor was conducted by utilizing both SIDRA and Microsoft excel. Based on the result of analysis multi variable linear regression model, the imbalance between vehicle volume and road capacity, number of pedestrians that cross and move along the side of the road, inflexible work schedule, inadequate mass transit service along the corridor and illegal on street vehicle parking were identified as the main causes of traffic congestion over the road corridor. As the result from SIDRA and Microsoft excel showed that the intersections along the corridor and the road corridor in section C were operating beyond the standard set by HCM 2010 which recommends LOS ‘C’ or ‘D’. As per the economic analysis result of the study showed about 2667.8 person-hours/year and ETB104048.75 /year per individual traveler are being wasted due to traffic congestion over the study road corridor. Building vehicle parking apartment, elevated pedestrian crossway and improving performance of intersections were some of the engineering measures recommended to overcome the traffic congestion problem of the corridor.
INFLUENCE OF WATER CONTENT AND DRY DENSITY ON THE SHEAR STRENGTH CHARACTERSTICS OF REMOLDED EXPANSIVE SOILS IN ADDIS ABABA, THE CASE STUDY OF KOYE AREA
(Hawassa University, 2020-03-19) TEMESGEN ASFAW ANTE
OPERATIONAL ANALYSIS OF UNSIGNALIZED INTERSECTION AND ROUNDABOUT UNDER MIXED TRAFFIC FLOW CONDITION OF SELECTED INTERSECTIONS IN ADAMA CITY
(Hawassa University, 2020-10-06) DARARA BERHANU KURU
Urban traffic congestion is currently severe in most cities in the world due to economic and social development. Prevalently, Ethiopia is one of the countries that are in rapid economic development. This influences the travel pattern of the community from their origin to any destination. Adama is one of busy transportation center in Ethiopia. The city is situated along the road that connects Addis Ababa with Dire Dawa. A large number of trucks use this same route to travel to and from the seaports of Djibouti. A little attention has been paid to junctions and their capacities. There are a few studies conducted to assess the capacity of junctions in Adama. The main objective of this study was to evaluate operational performance on both unsignalized and roundabout junctions which are necessary for transport professional’s and governors to put tangible information for future traffic growth of Adama city. This thesis addresses the most important element of operational performance of unsignalized intersections and roundabouts traffic intersections in Adama City on capacity analysis. The methodology employed for this study was the quantitative descriptive research design which used quantitative data and analyzed using SIDRA 8.1 intersection software model. The movements of the vehicles were observed at three roundabouts and seven unsignalized intersections for a duration of two hours. The necessary geometric data for the analysis (average entry width, circulatory road width, number of entry and circulatory lanes, and island diameter), traffic movement data with vehicle characteristics and pedestrian volume were collected. The capacity analysis was done based on the gap acceptance method that is adopted by SIDRA 8.1 software program. Based on analysis results, Derartu Tulu roundabouts and six of selected unsignalized intersections i.e Mebrathayil,Sartera,Wonji,Tikur Abay and Alem Hotel junctions are currently serving in poor condition of level of service of F by having v/c ratio >1. Genda Gara and Medanihalem roundabouts are serving at their best operating condition having level of service A.The rest two unsignalized intersection Geda and Diamond Cafe have level of service of D and C respectively. The overall level of service of the unsignalized intersections and roundabouts are serving at poor level of service. Thus, after carrying out additional detail investigation and taking into consideration future traffic growth appropriate improvement should be made by concerned bodies
CONSTRUCTION HEALTH AND SAFETY LEGISLATION, COMPARING ETHIOPIA AND UNITED STATES OF AMERICA
(Hawassa University, 2020-10-12) BITSEAT ZELEKE TESFAYE
Construction industry has various risks due to the activities, individuals and many companies in different scales that it contains. Besides, construction materials, machinery, tools, tasks and handling skills all come with their own risks. Therefore, construction industry is prone to many potential hazard and accident. Accidents can be avoided mostly by implementing health and safety laws and regulations by ensuring those protocols are continuously maintained. In this study, Ethiopian construction health and safety legislation are discussed and suggestions for amendments are recommended. As different researches show that the Ethiopia construction industry has a safety problem moreover, the safety legislations are not being enforced in careful way. Therefore, in order to minimize the problem observed, it is recommended to amend and modify current legislation and control strategies with different ways of enforcement in construction industry to more rigorous legislation and control practices to enhance construction safety level in Ethiopia. Moreover, for making a better legislation and for recommending on how to amend the current legislation, comparison is made with comparative study by document review. The comparison is between American and Federal Democratic Republic Ethiopia (FDRE) construction OHS legislations and laws from the point of view of thirteen topics, the two countries have different legislative systems and implementation method, and which are from different continents, but America has strong economy and strong construction industry better than Ethiopia. There is no hesitation that the America is one of the world’s leaders in Occupational Health and Safety (OHS) issue. As the comparison shows their exist key difference across the Legislations, from those the American Act states employer and employee’s right and responsibility in detail and obligate the employer to make the workers aware of their right under the Act but Ethiopian neither include any rights of workers nor obligate employers to aware workers right. Moreover, Best practice and lessons from American legislation is included on the comparison, like some crucial ideas are left out and not included in the legislation of Ethiopia. I.e. precaution for Concrete construction, Conveyor, Cranes and Derricks, Precaution for Confined space are some lessons. The differences of these two countries OHS legislation and weakness of the OHS legislation of Ethiopia were acquired, with some suggestions legislations were promoted to be more beneficial and the findings of the study provide the gap exist on Ethiopian construction health and safety legislation’s and recommend on gaps found and insights XVII and discussions are given and recommend for reviewing FDRE health and safety legislation. It was concluded from the study that the legislation of Ethiopia have some gaps which does not clearly state different terms in detail. Specifically Ethiopian Building Proclamation does not clearly identify the scope of application of the proclamation moreover, the scope of exclusion under Ethiopian Building Construction Standard (EBCS) 14 demolishing work, is narrow and does not provide sufficient information and do not consider current construction method of Ethiopia
SIMULATION OF PILE LOADING TEST IN A LAYERED SOIL WITH VERTICAL LOADING BY USING FINITE DIFFERENCE METHOD BASED SOFTWARE
(2020-10-13) BEREKET GEBRESELASSIE GIRMAY
Pile loading tests are usually performed in various projects to determine the ultimate pile capacity. However, the cost of running these tests and the time it takes is one of the difficulties that engineers face in current geotechnical practices. Finite difference method and finite element methods have comparable accuracy. However, finite difference method based tool was used for the analysis due to its simplicity, computational efficiency and simple structure codes. The research presents a numerical simulation of pile loading test using a finite difference program “FLAC 3D”. The chosen software is memory and simulation time efficient. It solves almost all kinds of geotechnical problems, but the only downside is that it initially takes some time to get the feel of the software, but once understood, it can solve any problem and it also supports a wide range of material models. The objective of this study is to simulate a pile load test with vertical loading in a layered soil, in order to estimate the load-settlement characteristics and to determine the effect of young’s modulus, angle of internal friction, lateral earth pressure coefficient, and the dilation angle on the load-settlement curve. Input parameters of the simulation were collected from Nib, United, and Zemen international bank's new headquarter projects. In the case of piles with incomplete data, the parameters were estimated from site experience data and/or using different equations obtained from a literature. The proposed numerical model has been validated with field data and published results provided by other studies. The validation produced good results with a minor deviation except for nib bank piles. The significant deviation in nib bank piles is due to the generalized soil parameters used in the analysis. The numerical analysis underestimated the ultimate pile capacity. However, Lateral pressure coefficient manipulation yields improved results. Underprediction of load-settlement curves of nib bank piles was due to lower young’s modulus values estimated from various equations. The study on one of the piles showed that the base resistance carries the upper hand of the total capacity. The importance of using finer mesh near high-stress gradient zones was examined and it has been found that finer mesh generated based on the developed relation produced a good performance. If the required constitutive model, initial and boundary conditions, and good quality input data are available, the proposed numerical model can be used as an alternative method for the design purpose on projects involving pile foundations
PREDICTION OF UNDRAINED SHEAR STRENGTH AND SWELLING PRESSURE OF FINE GRAINED SOIL USING ARTIFICIAL NEURAL NETWORK BASED MODEL: THE CASE OF KOYE FECHE SITE
(Hawassa University, 2020-12-16) TEFERI WORKAFERAHU
This research presents an Artificial Neural Network based correlation of undrained shear strength and swelling pressure with the standard index test results of Koye-Feche fine grained soil. Simple index test results used for the analysis include unit weight, natural moisture content, liquid limit, plastic limit, liquidity index and plasticity index. Unlike conventional methods, ANNs do not depend on simplified assumptions, have universal function approximation capacity, noisy or missing data resistance, accommodate multiple nonlinear variables for unknown interactions, and have a good generalization capability. A total of four models were proposed for prediction. The first three models were produced for Cu while the remaining one was developed for Ps. Swelling pressure and undrained shear strength were trained in an ANNs program and the results were compared with the experimental values. An automated optimization script has also been developed that can be successfully used to pick the optimal network architecture. Performance indices (i.e. Correlation coefficient and root mean square error) were computed to check the prediction capacity of the ANN models. The devised ANN model was compared with the conventional regression analysis and found superior in all cases. The results obtained from ANN and existing empirical formulas were compared to those obtained from the experiments. It was found that the values predicted from the ANN models match the experimental values much better than those obtained from the equations. Undrained shear strength results showed a strong correlation with the combined Liquid Limit and Plasticity Index input parameters. Whereas, Dry unit weight, natural moisture content, liquid limit and plastic index are powerful predictor of swelling pressure. It has been verified that the ANN models can be used satisfactorily to predict undrained shear strength and swelling pressure as a rapid inexpensive substitute for laboratory techniques. Further research should be conducted to extend all aspects of this research, such as by collecting more data in order to improve results
ASSESING PERFORMANCE EVALUATION PRACTICE OF BUILDING CONSTRUCTION PROJECT IN HAWASSA CITY
(Hawassa University, 2021-03-18) BIRUK KEBEDE BEKELE
Project performance has been considered to be tied to project success and this is also tied to project objectives. Based on this to evaluate performance effectively and efficiently we should develop an objective and consistent measurable criteria. These criteria are called performance dimensions. According to many study performance dimension has been encounter performance shortfall in construction industry worldwide and in developing country at large. Especially in Ethiopia and the city Hawassa the problem is clearly shows. The research aimed at assessing the performance evaluation practice on four Dimensions namely Time, Cost, Quality and health and safety and its challenges and also develops a framework to efficiently practice performance evaluation in construction project in Hawassa city. The study adopts both quantitative and qualitative approach to assess the performance evaluation practice in Hawassa city. Simple random samplings were used to select the representative sample form entire population. Quantitative approach used questionnaire while qualitative approach uses semi-structure interview and case study to stimulate the relevant response from the major stakeholders in the Hawassa building construction project. The data collected by questionnaire were analyzed using frequency and mean for objective one and one sample t-test for objective two. In doing so The study concludes most contractors has limited budget set for evaluation purpose, most contractor evaluate their project in every phase of project. And most contractor use “time variation” formula to measure time, percent net variation over final cost formula to measure cost, system quality method to measure quality, fatality rate to measure safety. The study found that, limited financial resource, poor quality of data collected, poor communication, lack of monitoring and evaluation plans in planning, and budgeting, weak legal and institutional framework and Poor demand for monitoring and evaluation. Lack of monitoring and evaluation units within the organization and Weak linkage between planning and evaluation are the most challenges in Hawassa construction project. And all projects never use the most common framework like Balance score card, European foundation for quality management, Key Performance Indicator and Earned Value Management. Finally the research recommends that contractors in Hawassa should allocate budget, use reliable framework and organize independent unit for performance evaluation. The study develops performance evaluation framework helps to project success and uses as benchmark for other study in Hawassa cit
FINITE ELEMENT ANALYSIS OF REINFORCED CONCRETE COLUMN WITH CORE DRILLIN
(Hawassa Unversity, 2021-07-17) BILISUMMAA ARARSA DEMISSIE
Reinforced concrete column is one of the compression structural member carry axial or slightly slanted compressive loads, with or without moment. In RC column opening provided for multiple purpose such as plumbing of pipes and electric wiring. The provision of such openings may result in the loss of strength, stiffness and ductility. Therefore, providing core hole needs some precaution in account of failures of the column. Most of researchers have studied effect of opening considering, hole position, hole diameter, hole shape and grade of concrete. However, there is lack of study on drilling concrete core with considering of steel grade, reinforcement area ratio, level of service load. Therefore, this study demonstrates finite element analysis of reinforced concrete column with drilled concrete core considering effect of opening in account of steel grade, reinforcement area ratio, level of service, cross section of column and drilling location. It shows deformation versus column capacity, concrete vertical strain, bar strain distribution around hole, capacity reduction relative to controlling specimen, core position effect and P-delta effect. Finite element analysis consist initial step associated with boundary condition and first step which nonlinear static stress analysis takes place. For checking accuracy of finite element analysis validation performed with available experimental literature. The results from finite element simulation of hole effect indicates; Increase grade of reinforcement; improve capacity of drilled column and axial deformation decreased by the range 6.18 % up to14.59 % relative to solid column. Reinforcement area ratio reduces axial deformation 31.2% between drilled specimens and cross-section of column increases; deformation decrease 18.18% axial deformation. In addition to this; hole position at end side has large reduction in axial capacity of column and resulted increase lateral deformation. Hole at end side has greater effect in lateral deformation relative to axial deformation
ASSESSEMENT ON THE CHALLENGES AND EFFECTIVENESS OF PEAK HOUR TRAFFIC MANAGEMENT IN ADDIS ABABA: A CASE STUDY FROM MEGENAGNA TO AYAT ROAD
(Hawassa University, 2021-10-11) ASTEWAY MEKONNEN TENAW
Beside the construction of a high quality road network, managing operational performance of the highway system directly increases a nation’s economic output by reducing travel time and costs. The Addis Ababa Traffic Management Agency tries to implement different remedial measures on the city arterials which aim to improve their operational performance; especially during the day’s peak period. Measuring the challenges and effectiveness of those management practices in the capital is the focus and novelty of this research. Due to its representative nature with two ways and an eight lane geometric feature, the route from Megenagna to Ayat is selected as a cases study. Observations like congestion pattern, video recording, direct field measurements and secondary data were the main sources for the analysis. Volume to capacity ratio analysis method was used to measure the existing operating performance of the route. The method of queue and delay analysis in working zone areas was used to quantify the delay on the route. Results from the performance analysis shows that, congestion is a concept beyond the serving capacity of roadway facilities. Even though the maximum traffic flow exhibited is only 80% of the road segments capacity, results from the queue analysis shows 255 veh-hr vehicles in waiting to traverse the segment. The delay analysis also shows a need of extra 13.74 minutes to clear the queued vehicles. Interruption from pedestrians and diverted vehicles, bottleneck geometrical features and safety conditions are the main identified challenges of the traffic management practice. Implementing the reversible lane as a remedy helps in diverting up to 21.22% of the peak traffic to the less congested direction and decreased the time loss by 1.67 minutes. Regulating the random crossing pattern of pedestrians, cycle time increment of traffic light on specific segments and restricting usage of on street parking during peak periods are proposed recommendation to improve the traffic flow.
ASSESSMENT OF THE IMPACT OF RURAL ROAD TRANSPORT ON SOCIO-ECONOMIC DEVELOPMENT.
(Hawassa University, 2021-10-14) ARARSA BEKELE KILISA
Roads are the dominant mode of transportation in Ethiopia but it has been neglected to a large extent in the past, Socio-economic development and subsequent economic growth on the country is hampered by several limiting factors, including the lack of adequate roads infrastructure. Investment in transport infrastructure plays a significant role in stimulating development. An increased interest in rural roads investment potential has developed in recent years. This is mainly due to the need for development of rural as well as the positive impact that road investment could generate on rural communities, should they have an adequate support roads infrastructure network that is sustained over the long term. Due to improvement in transportation network, reduction in transportation costs can be realized in numerous ways, such as reduction in travel time, decrease in vehicle operating costs, increased safety and reduction in the level of air and noise pollution. In addition to reduction in transportation cost, it also increase comfort to passengers and also enhancing land value. Economic analysis is a critical component of a comprehensive project evaluation methodology that considers all key quantitative and qualitative impacts of road. The scope of present study consists of evaluating the impact on rural road investment and checking economic viability of the project. Maintaining and upgrading for two lanes with gravel shoulder of flexible pavement road namely, Tulla Kenera Yaye Section of TKY is taken as a case study. In spite of heavy initial investment in maintaining and upgrading to two lane with gravel shoulder of flexible pavement, economic analysis carried out using HDM-IV and RED model results indicates that there is great saving towards Vehicle Operating cost (VOC) and Travel Time cost (TTC) after maintenance. The paper also indicates the benefits of rural road investments as well as the type of mechanisms used in practice to estimate its impact
STRUCTURAL PERFORMANCE OF ME-PET FIBER REINFORCED CONCRETE
(Hawassa University, 2021-10-18) ADDIS ALEMAYEHU KIYAMO
The aim of this paper is to investigate the effectiveness of manufacture embossed polyethylene terephthalate (PET) fibers in enhancing strength, deformation and durability of C25 concrete. This was achieved by both (i) adding to the concrete mix these above said recycled polyethylene fibers and (ii) maintaining the C25 plain concrete without the fibers for control purposes. Fresh properties of concre was prepared with the addition of various percentages of the PET fiber at 0, 0.5, 1.0, 1.5 and 2% of the concrete by volumetric fractions. Compressive strength tests were performed on forty-two (42) 150mm concrete cubes and splitting tensile strength tests were performed on twelve (12) (150*300) mm cylinder with the addition of various percentages of the PET fiber at 0, 0.5, 1.0, 1.5 and 2% of the concrete by volumetric fractions. Flexural strength tests were also performed on fifteen (15) 150mm×150mm×600mm concrete beams with the addition of PET fibers at 0, 0.5, 1.0, 1.5, and 2.0% of concrete by volume. The other parameter considered was deflection behavior the concrete beams with the mentioned amounts of fiber addition. To study the durability properties, 90 days’ compressive strength test, water absorption test, and effect of elevated temperature on residual compressive strength test were conducted on C25 concrete. The test results showed a significant increase in compressive and splitting tensile strength up to 21% and 27% at 1.0% of PET fiber respectively. Flexural strength of the concrete beams on the other hand increased by 17.5% for 1.0% fiber concrete compared to the control. The results of deflection performance of concrete beam with PET fibers also produced larger deflections at near maximum load.
GEOTECHNICAL INVESTIGATION ON CAUSES OF ROAD FAILURE OF DODOLA –GOBA ASPHALT ROAD PROJECT AND THEIR REMEDIAL MEASURES
(Hawassa University, 2022-10-06) BEREKET DEBEBE ESHETE
Dodola – Goba asphalt road, found in South East Ethiopia, was prematurely failed before serving its design life. From total stretch (130km) of the project, this study focus and detail investigations has been carried out on Adaba -Dinsho road section which was failed critically within 3 (three) years after it has been opened for traffic. A number of maintenance had been performed to make the road passable, but each maintained sections are failing with in short period. In this study, the real cause of the road failures has been identified and proper remedial measurements for failed section has been proposed. To asses this, field and laboratory investigations which includes visual inspection, field test, physical measurements and laboratory tests to determine geotechnical properties of sub grade, sub base and base course materials by comparison of the materials quality as per ERA 2014 and/or AASHTO design manuals were carried out. Finally based on the investigation, presence of too much moisture content on sub grade and pavement materials due to improper design and late maintenance of drainage, improper geometrical design, moisture sensitive geology/soil and seasonal variation of ground water are the major factors of failures. Also poor geotechnical properties of road base and sub base of materials due to substandard material quality and improper construction methods are the major causes of road failures. Correcting drainage system and geometric design of the road and reconstruction of pavement layers by standard material quality and methods are the proper remedial measure for failed section
Land Degradation Dynamics Under Land Use Land Cover and Climate Change Projection Towards the Appraisal of Potential Soil and Water Conservation Practices in the Gidabo Watershed, Ethiopian Rift Valley Lakes Basin
(Hawassa University, 2024-10-11) Rediet Girma Legesse
The intricate relationship between land use, climate dynamics, and land degradation profoundly impacts the sustainability of ecosystems and human well-being in Ethiopia. This study, conducted in the Gidabo Watershed (GW) within the Ethiopian Rift Valley Lakes Basin (ERVLB), aimed to assess the long-term land use land cover (LULC), evaluate regional climate models (RCMs), assess land degradation indicators, and propose management alternatives. To address these objectives, multidisciplinary approach integrating, remote sensing, geospatial analysis, statistical metrics and hydrological modeling were used. The study identified nine major LULC classes i.e., water body, grass land, forest, agriculture, bare/barren land, built-up, agroforestry, shrub and marsh land. The watershed experienced significant LULC changes between 1985 and 2021, predominantly driven by agricultural expansion at the expense of forest, shrub, and grasslands. Future (2035 and 2050) projections using a hybrid Multi-Layer Perceptron (MLP) and Cellular Automata-Markov chain (CA-MC) model indicated further agricultural expansion, accompanied by declines in forest and grasslands. Furthermore, the study evaluated 11 CORDEX-Africa RCMs and their mean ensemble performance, revealing varied accuracies in reproducing rainfall and temperature patterns over GW from 1991 to 2005. The observed climate trends indicated a significant declining rainfall (-13.38 mm/year) and warming temperatures, with future projections (RCP4.5 and RCP8.5) showing consistent temperature increases. Additionally, the study investigated the impact of LULC and climate change on surface runoff and sediment yield using SWAT model. The results revealed notable increases in surface runoff and sediment yield attributed to LULC changes. Whereas, climate change alone exhibited a diverse influence, with both increases and decreases in surface runoff and sediment yield. Similarly, the combined effects of LULC and climate change demonstrated that certain scenarios led to the increases in surface runoff and sediment yield, while others reduced these processes. This might be attributed to the offset of runoff and sediment reduction by climate change. Soil erosion rates were found to be high, particularly most of the southern and eastern parts of the watershed will generate the highest amount of surface runoff and sediment yield in to the future. Addressing these concerns, soil/stone bund, terracing, contour farming, and reforestation practice can significantly reduce the annual sediment yield in the future. The land degradation neutrality (LDN) assessment from 1985–2003 to 2003–2021 revealed land productivity decline, land cover degradation, SOC loss, and the expansion of land degradation trajectories by 26%. Overall, the findings provide valuable information for stakeholders.