The rapid development in construction and material technology arising the needs for simple techniques to increase the shear strength of RC box beams. This paper is devoted to investigating experimentally the structural behavior of RC box beams which have internal in-plane solid diaphragms under the effect of shear stresses. For this purpose, four beam specimens with (200x300x1200mm) dimensions are poured using normal strength concrete of class ( f' c =22MPa) and longitudinal flexural steel of class ( f y =410MPa) without transverse reinforcement (stirrups). Three of these specimens were a box with or without different locations of internal diaphragms and one of them was a solid. The number of the internal diaphragms is the major variable adopted in this study, while, the other variables are kept constant for all tested specimens. The experimental results indicated that the shear strength is increased for about (35%) to (47%) for beams containing internal in-plane diaphragms in comparison with the reference beam. Also, the change of beam section from box section to solid section led to increasing the capacity for about (100%). Keywords: Shear Failure, Box Beam, Reinforced Concrete, Diaphragms, ACI-318 Code DOI: 10.7176/CER/12-8-06 Publication date: August 31 st 2020
{"title":"Shear Failure Control of RC Box Beams Using Internal Transverse Diaphragms","authors":"A. Aziz, D. Hamza","doi":"10.7176/cer/12-8-06","DOIUrl":"https://doi.org/10.7176/cer/12-8-06","url":null,"abstract":"The rapid development in construction and material technology arising the needs for simple techniques to increase the shear strength of RC box beams. This paper is devoted to investigating experimentally the structural behavior of RC box beams which have internal in-plane solid diaphragms under the effect of shear stresses. For this purpose, four beam specimens with (200x300x1200mm) dimensions are poured using normal strength concrete of class ( f' c =22MPa) and longitudinal flexural steel of class ( f y =410MPa) without transverse reinforcement (stirrups). Three of these specimens were a box with or without different locations of internal diaphragms and one of them was a solid. The number of the internal diaphragms is the major variable adopted in this study, while, the other variables are kept constant for all tested specimens. The experimental results indicated that the shear strength is increased for about (35%) to (47%) for beams containing internal in-plane diaphragms in comparison with the reference beam. Also, the change of beam section from box section to solid section led to increasing the capacity for about (100%). Keywords: Shear Failure, Box Beam, Reinforced Concrete, Diaphragms, ACI-318 Code DOI: 10.7176/CER/12-8-06 Publication date: August 31 st 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76254969","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}
This paper investigates the load carrying capacity development of concrete filled bamboo columns when subjected to static axial loads. Concrete Mix C20 and C30 were used to fill bamboo of different diameters and slenderness ratios. Compression tests were performed using Uniaxial Compression Machine under a loading rate of 31 Kn/s. Results revealed that increase in concrete grade had significant effect on the carrying capacity and crushing stresses with C20 increasing the load capacity of concrete filled bamboo by 0.8 times while C30 by 1.5 times. The carrying capacity increases as the diameter of the column is increased but decreases as the slenderness ratio is increased due to reduced stiffness of the column. Increase in column diameter reduces the crushing stresses due to increased carrying area. Deformation behavior showed that specimens filled with concrete mix C20 are more ductile and undergoes large displacements before failure while C30 specimens showed brittleness characteristics in all samples. Keywords: Bamboo. Concrete column, Ductility, Buckling, Deformation, Ultimate failure. DOI: 10.7176/CER/12-8-05 Publication date: August 31 st 2020
{"title":"Structural Behavior of Concrete Filled Bamboo Columns Under Axial Loads","authors":"Shitabuleh Stephen, Sabuni Bernadette, K. Bruce","doi":"10.7176/cer/12-8-05","DOIUrl":"https://doi.org/10.7176/cer/12-8-05","url":null,"abstract":"This paper investigates the load carrying capacity development of concrete filled bamboo columns when subjected to static axial loads. Concrete Mix C20 and C30 were used to fill bamboo of different diameters and slenderness ratios. Compression tests were performed using Uniaxial Compression Machine under a loading rate of 31 Kn/s. Results revealed that increase in concrete grade had significant effect on the carrying capacity and crushing stresses with C20 increasing the load capacity of concrete filled bamboo by 0.8 times while C30 by 1.5 times. The carrying capacity increases as the diameter of the column is increased but decreases as the slenderness ratio is increased due to reduced stiffness of the column. Increase in column diameter reduces the crushing stresses due to increased carrying area. Deformation behavior showed that specimens filled with concrete mix C20 are more ductile and undergoes large displacements before failure while C30 specimens showed brittleness characteristics in all samples. Keywords: Bamboo. Concrete column, Ductility, Buckling, Deformation, Ultimate failure. DOI: 10.7176/CER/12-8-05 Publication date: August 31 st 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"39 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72630609","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}
This study was conducted by aiming quantification of the potential of rooftop rainwater harvesting (RT-RWH) in general and (1) comparing alternative methodologies for measuring roof catchment areas, (2) analyzing demand-supply gap between harvested rainwater and toilet flushing water demand in particular for the study area. A comparison was made between the roof catchment area measurement techniques such as; Google Earth (GE), Master Plan and field survey. The coefficient of determination (R 2 ) was used as a comparison tool for deciding which measurement techniques are better, so as to recommend for accurate usages for practical purposes for roof catchments areas measurements. Hence, R 2 values of field measurement versus Master Plan, field measurement versus GE, and Master Plan versus GE were found to be 0.997, 0.959 and 0.971 respectively. In the meantime, it was proved that measuring roof catchment areas by the Master Plan is better than GE for the case of this study area. In addition to this, the water harvesting potential of the study area was estimated and compared with the toilet flushing water demand (which accounts for the major portions of domestic water demand of the study area). The annually harvested rainwater of the study area was estimated to be 1 25,172m 3 and the respective annual toilet flushing water demand was 6,090,314m 3 . This result showed that 18.13% of water consumption of toilet flushing of the study area could be covered by the harvested rainwater, which is an indispensable figure to alleviate and minimize the ever-increasing water scarcity of the study area to some extent. Keywords: Rooftop-Rainwater Harvesting; Google Earth; Field Survey; Master Plan; Potential Assessment DOI: 10.7176/CER/12-8-03 Publication date: August 31 st 2020
{"title":"Investigation on Rooftop Rainwater Harvesting Potential and Roof Catchment Area Measurement Techniques in Addis Ababa, Ethiopia","authors":"Yalemzewd Abere Mulu","doi":"10.7176/cer/12-8-03","DOIUrl":"https://doi.org/10.7176/cer/12-8-03","url":null,"abstract":"This study was conducted by aiming quantification of the potential of rooftop rainwater harvesting (RT-RWH) in general and (1) comparing alternative methodologies for measuring roof catchment areas, (2) analyzing demand-supply gap between harvested rainwater and toilet flushing water demand in particular for the study area. A comparison was made between the roof catchment area measurement techniques such as; Google Earth (GE), Master Plan and field survey. The coefficient of determination (R 2 ) was used as a comparison tool for deciding which measurement techniques are better, so as to recommend for accurate usages for practical purposes for roof catchments areas measurements. Hence, R 2 values of field measurement versus Master Plan, field measurement versus GE, and Master Plan versus GE were found to be 0.997, 0.959 and 0.971 respectively. In the meantime, it was proved that measuring roof catchment areas by the Master Plan is better than GE for the case of this study area. In addition to this, the water harvesting potential of the study area was estimated and compared with the toilet flushing water demand (which accounts for the major portions of domestic water demand of the study area). The annually harvested rainwater of the study area was estimated to be 1 25,172m 3 and the respective annual toilet flushing water demand was 6,090,314m 3 . This result showed that 18.13% of water consumption of toilet flushing of the study area could be covered by the harvested rainwater, which is an indispensable figure to alleviate and minimize the ever-increasing water scarcity of the study area to some extent. Keywords: Rooftop-Rainwater Harvesting; Google Earth; Field Survey; Master Plan; Potential Assessment DOI: 10.7176/CER/12-8-03 Publication date: August 31 st 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90452032","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}
Currently the impact of climate change affects many water resources projects that result in pattern change of annual runoff, reservoirs pool level change, increasing of irrigation demand due to increasing temperature and evaporation and etc., and thus it is important to assess its impact on streamflow. This study mainly forecast streamflow of Dabus river Sub Basin. The future climate variables which were downscaled by Climate Limited area Model (CLM) at the basin level for A1B emission scenario was used for future flow simulation. For streamflow generation HEC-HMS model was used by using the bias corrected precipitation and Evapotranspiration which was estimated by FAO Penman-Monteith. After the flow was forecasted, the performance of the model was assessed via calibration at Dabus near Asosa, Sechi near Mendi and Aleltu at Nedjo using Relative Volume Error (D), coefficient of determination (R 2 ) and Nash-Sutcliffe Efficiency (NSE) performance coefficients. Then the model was validated using the parameters optimized during model calibration. The trend of Dabus streamflow forecasted at its outlet to main basin river (Abbay River) was assessed. The projected mean annual maximum temperature increases from the baseline period by 0.43 0 C, 1.3 0 C and 2.5 0 C for short-term, midterm and long-term respectively whereas minimum temperature increases by 0.47 0 C, 1.53 0 C and 2.83 0 C. Generally the projected future maximum and minimum temperature shows an increasing trend whereas precipitation shows variation (does not reveal clearly increasing or decreasing) for earlier century and decreasing trend in mid and late century. The evapotranspiration shows an increasing trend. The HEC-HMS model shows a good performance at Dabus near Asosa which resulted D=0.0066, R 2 =0.90 and NSE=0.89 during calibration and D=4.9285, R 2 =0.84 and NSE=0.82 during validation. The streamflow of Dabus River Basin shows an average annual increase of 2.83% for short-term forecast (2011-2040) and decrease of 2.83% and 4.56% for mid-term forecast (2041-2070) and long-term forecast (2071-2100) respectively.
{"title":"Streamflow Modeling Under the Impact of Climate Change. (Case Study of Dabus River Sub-Basin, Ethiopia)","authors":"J. Mohammed","doi":"10.7176/cer/12-7-03","DOIUrl":"https://doi.org/10.7176/cer/12-7-03","url":null,"abstract":"Currently the impact of climate change affects many water resources projects that result in pattern change of annual runoff, reservoirs pool level change, increasing of irrigation demand due to increasing temperature and evaporation and etc., and thus it is important to assess its impact on streamflow. This study mainly forecast streamflow of Dabus river Sub Basin. The future climate variables which were downscaled by Climate Limited area Model (CLM) at the basin level for A1B emission scenario was used for future flow simulation. For streamflow generation HEC-HMS model was used by using the bias corrected precipitation and Evapotranspiration which was estimated by FAO Penman-Monteith. After the flow was forecasted, the performance of the model was assessed via calibration at Dabus near Asosa, Sechi near Mendi and Aleltu at Nedjo using Relative Volume Error (D), coefficient of determination (R 2 ) and Nash-Sutcliffe Efficiency (NSE) performance coefficients. Then the model was validated using the parameters optimized during model calibration. The trend of Dabus streamflow forecasted at its outlet to main basin river (Abbay River) was assessed. The projected mean annual maximum temperature increases from the baseline period by 0.43 0 C, 1.3 0 C and 2.5 0 C for short-term, midterm and long-term respectively whereas minimum temperature increases by 0.47 0 C, 1.53 0 C and 2.83 0 C. Generally the projected future maximum and minimum temperature shows an increasing trend whereas precipitation shows variation (does not reveal clearly increasing or decreasing) for earlier century and decreasing trend in mid and late century. The evapotranspiration shows an increasing trend. The HEC-HMS model shows a good performance at Dabus near Asosa which resulted D=0.0066, R 2 =0.90 and NSE=0.89 during calibration and D=4.9285, R 2 =0.84 and NSE=0.82 during validation. The streamflow of Dabus River Basin shows an average annual increase of 2.83% for short-term forecast (2011-2040) and decrease of 2.83% and 4.56% for mid-term forecast (2041-2070) and long-term forecast (2071-2100) respectively.","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85124597","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}
Groundwater is a vital water source in arid and semi-arid regions. In East Owienat area groundwater is an only available water source. This study assessed the characteristics of the hydrogeological system and the baseline condition of the aquifer using field data and numerical modeling. The main objective of this research is to study the impacts of groundwater development on groundwater aquifer sustainability and to select the optimum development scenario, which achieves sustainable development with a minimal effect on aquifer potentiality. Groundwater flow was simulated using the Visual MODFLOW package. The model was calibrated under steady state conditions in January 1985. The model was verified from January 1985 to January 2018 according to observation point's data. The calibrated model then was used for the prediction simulations. Different extraction scenarios were suggested and evaluated to predict the behavior of groundwater aquifer and select the most feasible scenario. The evaluated groundwater extraction scenarios included: current extraction, proposed extraction and seasonally pumping of groundwater scenario. The results indicated that the seasonal operational aquifer scenario is highly recommended for a long-term management plan to achieve groundwater sustainability. This paper presents the different proposed scenarios to achieve sustainability of groundwater development in East Owienat area. The conclusions from the present study are mainly based on the field data analysis which was used to detect the prevailing hydrogeological environment. The concept of the study proposed a long term management plan to achieve sustainability. A conceptual flow model (MODFLOW) was implemented to simulate and calibrate the groundwater flow in East Owienat area based on the groundwater levels during the period between January 1985 (before starting the reclamation activities) and January 2018. Four scenarios were evaluated based on the final results of the verification period (1985-2018) to predict the impact of the different groundwater withdrawals on the aquifer behavior with time. The output of the four future scenarios (maps and graphs) was a helpful tool to predict the future hydrogeological situation of the aquifer system and to select the reliable, applicable and secure scenario as outlined for long term sustainable development. Before starting the groundwater development in East Owienat, the initial groundwater regional flow was flowing from southwest to northeast direction. While by continuous groundwater development, the flow was changed as radial flow towards the center of the well field in the development area, as a result of the excessive groundwater extraction. Application of numerical modeling has been proven to be efficient and accurate. It proved that the seasonal operational aquifer scenario is highly recommended for a long term management plan to achieve groundwater sustainability. More aquifer operation scenarios should be trying to
{"title":"Sustainable Development of Groundwater in East Owienat, Egypt","authors":"H. Abu-Bakr","doi":"10.7176/cer/12-7-06","DOIUrl":"https://doi.org/10.7176/cer/12-7-06","url":null,"abstract":"Groundwater is a vital water source in arid and semi-arid regions. In East Owienat area groundwater is an only available water source. This study assessed the characteristics of the hydrogeological system and the baseline condition of the aquifer using field data and numerical modeling. The main objective of this research is to study the impacts of groundwater development on groundwater aquifer sustainability and to select the optimum development scenario, which achieves sustainable development with a minimal effect on aquifer potentiality. Groundwater flow was simulated using the Visual MODFLOW package. The model was calibrated under steady state conditions in January 1985. The model was verified from January 1985 to January 2018 according to observation point's data. The calibrated model then was used for the prediction simulations. Different extraction scenarios were suggested and evaluated to predict the behavior of groundwater aquifer and select the most feasible scenario. The evaluated groundwater extraction scenarios included: current extraction, proposed extraction and seasonally pumping of groundwater scenario. The results indicated that the seasonal operational aquifer scenario is highly recommended for a long-term management plan to achieve groundwater sustainability. This paper presents the different proposed scenarios to achieve sustainability of groundwater development in East Owienat area. The conclusions from the present study are mainly based on the field data analysis which was used to detect the prevailing hydrogeological environment. The concept of the study proposed a long term management plan to achieve sustainability. A conceptual flow model (MODFLOW) was implemented to simulate and calibrate the groundwater flow in East Owienat area based on the groundwater levels during the period between January 1985 (before starting the reclamation activities) and January 2018. Four scenarios were evaluated based on the final results of the verification period (1985-2018) to predict the impact of the different groundwater withdrawals on the aquifer behavior with time. The output of the four future scenarios (maps and graphs) was a helpful tool to predict the future hydrogeological situation of the aquifer system and to select the reliable, applicable and secure scenario as outlined for long term sustainable development. Before starting the groundwater development in East Owienat, the initial groundwater regional flow was flowing from southwest to northeast direction. While by continuous groundwater development, the flow was changed as radial flow towards the center of the well field in the development area, as a result of the excessive groundwater extraction. Application of numerical modeling has been proven to be efficient and accurate. It proved that the seasonal operational aquifer scenario is highly recommended for a long term management plan to achieve groundwater sustainability. More aquifer operation scenarios should be trying to","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"99 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75823426","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}
Vulnerability to the impacts of land degradation has been frequently reported in Ethiopia. However, the level of vulnerability and its determinants vary in spatial and temporal. The objective of this study was to estimate farm households’ vulnerability to the impact of land degradation and its determinants in the Central Omo-Gibe river sub-basin, southwestern Ethiopia. Primary data were collected from 383 farm households using multistage random sampling techniques. The principal component analysis was employed to give different weights for indicators and estimate the households’ vulnerability index so as to categorize farm households based on their level of vulnerability . The result showed that 44.91%, 39.16% and 15.93% of the sample farm households were found to be less, moderately and highly vulnerable to the impact of land degradation, respectively. The ordered logistic regression result showed that age, sex, marital status, family size, dependency ratio, extension service, social participation, livestock ownership, land tenure security, land size and distance to the nearest main road, perceived reduction cropland productivity and plot-level land degradation affected households’ vulnerability to the impact of land degradation. Therefore, policymakers and local development practitioners should give priority to the highly vulnerable households focusing on the major factors affecting vulnerability strengthen human, financial, natural and physical including infrastructure and institutional capitals to minimize the impact of land degradation in the study area. Keywords: Land degradation, Vulnerability, Ordered logistic regression, Principal Component Analysis , Omo-Gibe basin, Ethiopia DOI: 10.7176/CER/12-7-01 Publication date: July 31 st 2020
{"title":"Determinants of Farm Households’ Vulnerability to the Impact of Land Degradation in the Central Omo-Gibe Basin, Ethiopia","authors":"Fisseha Seyoum","doi":"10.7176/cer/12-7-01","DOIUrl":"https://doi.org/10.7176/cer/12-7-01","url":null,"abstract":"Vulnerability to the impacts of land degradation has been frequently reported in Ethiopia. However, the level of vulnerability and its determinants vary in spatial and temporal. The objective of this study was to estimate farm households’ vulnerability to the impact of land degradation and its determinants in the Central Omo-Gibe river sub-basin, southwestern Ethiopia. Primary data were collected from 383 farm households using multistage random sampling techniques. The principal component analysis was employed to give different weights for indicators and estimate the households’ vulnerability index so as to categorize farm households based on their level of vulnerability . The result showed that 44.91%, 39.16% and 15.93% of the sample farm households were found to be less, moderately and highly vulnerable to the impact of land degradation, respectively. The ordered logistic regression result showed that age, sex, marital status, family size, dependency ratio, extension service, social participation, livestock ownership, land tenure security, land size and distance to the nearest main road, perceived reduction cropland productivity and plot-level land degradation affected households’ vulnerability to the impact of land degradation. Therefore, policymakers and local development practitioners should give priority to the highly vulnerable households focusing on the major factors affecting vulnerability strengthen human, financial, natural and physical including infrastructure and institutional capitals to minimize the impact of land degradation in the study area. Keywords: Land degradation, Vulnerability, Ordered logistic regression, Principal Component Analysis , Omo-Gibe basin, Ethiopia DOI: 10.7176/CER/12-7-01 Publication date: July 31 st 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"268 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77969841","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}
Ground investigation is a prerequisite for any construction work that ultimately transfers its loads to the earth. Geotechnical investigation eliminates the uncertainties of ground conditions and can be planned for and considered accordingly during actual design and construction. In Kenya, ground investigation is not given the weight it deserves since most players in the sector use their experience and physical inspection to judge on the soil conditions. This is however very risky especially for high-rise buildings. Moi University, the case study, is one of the institutions that has in its plan, a series of construction developments. This study aimed at investigating, determining and mapping of index properties and bearing capacity of subsurface soil. Direct shear box and tri-axial tests results were used to map soil bearing capacity by geospatial interpolation within geographical information system platform (GIS). 9 trial pits mapped by triangulation and visual inspection were excavated and soil samples obtained at a depth of up to 3 m. The soil samples were tested for soil index and engineering properties and classified using the USCS approach. A relationship between tri-axial and direct shear box test results was developed by correlating soil bearing capacity results from the two tests. This paper provides a thematic map of the bearing capacity for the study area derived from spatial interpolation. Four geospatial interpolation methods namely; Ordinary Kriging (OK), spline, Natural Neighbour (NN) and Inverse Distance Weighting (IDW) were used. In this paper, the most suitable method for interpolating the soil bearing capacity of the four methods is provided. Six of nine sample test results were used for interpolation and the other three used for validation and error correction. Ordinary Kriging generated satisfactory results for soil bearing capacity for the study area with a relative error of 2.23 % and R 2 of 0.9993. From the safe bearing capacity map, the ground conditions of the study area varied gradually with the bearing capacity ranging from to . Generally, the amount of clay in the soil within the area affected to a large extent, the soil bearing capacity. Keywords: Soil bearing capacity, Geospatial interpolation, Deterministic interpolation, correlation. DOI: 10.7176/CER/12-7-05 Publication date: July 31 st 2020
{"title":"Determination and Mapping of the Bearing Capacity of Subsurface Soil: A Case Study of Moi University, Eldoret Kenya","authors":"Sum Kipyego, Davis Sagini, B. Omondi","doi":"10.7176/cer/12-7-05","DOIUrl":"https://doi.org/10.7176/cer/12-7-05","url":null,"abstract":"Ground investigation is a prerequisite for any construction work that ultimately transfers its loads to the earth. Geotechnical investigation eliminates the uncertainties of ground conditions and can be planned for and considered accordingly during actual design and construction. In Kenya, ground investigation is not given the weight it deserves since most players in the sector use their experience and physical inspection to judge on the soil conditions. This is however very risky especially for high-rise buildings. Moi University, the case study, is one of the institutions that has in its plan, a series of construction developments. This study aimed at investigating, determining and mapping of index properties and bearing capacity of subsurface soil. Direct shear box and tri-axial tests results were used to map soil bearing capacity by geospatial interpolation within geographical information system platform (GIS). 9 trial pits mapped by triangulation and visual inspection were excavated and soil samples obtained at a depth of up to 3 m. The soil samples were tested for soil index and engineering properties and classified using the USCS approach. A relationship between tri-axial and direct shear box test results was developed by correlating soil bearing capacity results from the two tests. This paper provides a thematic map of the bearing capacity for the study area derived from spatial interpolation. Four geospatial interpolation methods namely; Ordinary Kriging (OK), spline, Natural Neighbour (NN) and Inverse Distance Weighting (IDW) were used. In this paper, the most suitable method for interpolating the soil bearing capacity of the four methods is provided. Six of nine sample test results were used for interpolation and the other three used for validation and error correction. Ordinary Kriging generated satisfactory results for soil bearing capacity for the study area with a relative error of 2.23 % and R 2 of 0.9993. From the safe bearing capacity map, the ground conditions of the study area varied gradually with the bearing capacity ranging from to . Generally, the amount of clay in the soil within the area affected to a large extent, the soil bearing capacity. Keywords: Soil bearing capacity, Geospatial interpolation, Deterministic interpolation, correlation. DOI: 10.7176/CER/12-7-05 Publication date: July 31 st 2020","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"112 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85490427","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}
M. Sidik, Adamu Ibrahim, F. Bondinuba, F.D.K. Fugar
This paper examines the underlying factors behind contractor selection in Ghana in terms of policy and practice. The paper relied on quantitative data with 199 respondents of consultants and clients of construction projects. Using factor analysis, five (5) factors emerged; managerial capabilities, quality standards, resource availability, duration, project cost and location as the most influential factors. The paper concludes that through the classification and/or reclassification of selection factors, practitioners and professionals would find it easier in using these factors to make very informed decisions in contractor selection for future projects and also help client achieve both economic and social value for money.
{"title":"Contractor Selection for Construction Works in Ghana: Towards Policy and Practice","authors":"M. Sidik, Adamu Ibrahim, F. Bondinuba, F.D.K. Fugar","doi":"10.7176/cer/12-7-07","DOIUrl":"https://doi.org/10.7176/cer/12-7-07","url":null,"abstract":"This paper examines the underlying factors behind contractor selection in Ghana in terms of policy and practice. The paper relied on quantitative data with 199 respondents of consultants and clients of construction projects. Using factor analysis, five (5) factors emerged; managerial capabilities, quality standards, resource availability, duration, project cost and location as the most influential factors. The paper concludes that through the classification and/or reclassification of selection factors, practitioners and professionals would find it easier in using these factors to make very informed decisions in contractor selection for future projects and also help client achieve both economic and social value for money.","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87619206","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}
Design and contract documentation processes which occur throughout the life cycle of the contract, is often mentioned an area that engenders contractual disputes in Ghana. This paper investigated the factors causing poor quality of design and contract documentation (DCD) and how this impact on successful project implementation in Ghana. It used questionnaire approach as the main method to obtain data which was analyzed using Relative Importance Index (RII) and Kendall’s concordance testing. Out of forty factors noted to contribute to DCD deficiencies, six were identified as critical: selection of designers on the basis of lowest price, unwillingness to pay fees commensurate with design services, last minute changes by clients, insufficient design reviews, inadequate clients’ briefs, slow payment systems and insufficient or missing input information from the client. To minimize or prevent DCD deficiencies in Ghana’s construction industry, the research recommends that briefs are adequate, clear and precise; consultancy fees are commensurate to the required service quality; consultants to ensure adequate review of design and contract documentation with all stakeholders and clients to select consultants based on merits. The measures suggested by the paper are believed to contribute to good quality contract documentation which can consequently improve project implementation in Ghana.
{"title":"Assessing the Factors that Cause Poor Quality of Design and Contract Documentation and the Influence on Project Implementation in Ghana","authors":"Abu Fatawu, I. Adamu, M. Sidik, Moo Fortunatus","doi":"10.7176/cer/12-7-08","DOIUrl":"https://doi.org/10.7176/cer/12-7-08","url":null,"abstract":"Design and contract documentation processes which occur throughout the life cycle of the contract, is often mentioned an area that engenders contractual disputes in Ghana. This paper investigated the factors causing poor quality of design and contract documentation (DCD) and how this impact on successful project implementation in Ghana. It used questionnaire approach as the main method to obtain data which was analyzed using Relative Importance Index (RII) and Kendall’s concordance testing. Out of forty factors noted to contribute to DCD deficiencies, six were identified as critical: selection of designers on the basis of lowest price, unwillingness to pay fees commensurate with design services, last minute changes by clients, insufficient design reviews, inadequate clients’ briefs, slow payment systems and insufficient or missing input information from the client. To minimize or prevent DCD deficiencies in Ghana’s construction industry, the research recommends that briefs are adequate, clear and precise; consultancy fees are commensurate to the required service quality; consultants to ensure adequate review of design and contract documentation with all stakeholders and clients to select consultants based on merits. The measures suggested by the paper are believed to contribute to good quality contract documentation which can consequently improve project implementation in Ghana.","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"42 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91404140","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}
Social distancing is one of the prescribed means of preventing the spread of deadly diseases such as COVID-19. This study aims at examining how the concepts of social distancing and self-isolation are affected by housing spatial conditions among the urban poor which comprise a demographic exposed to community spread in less-than-standard housing conditions. Through a qualitative assessment of the problem which comprised theoretical reviews and field observations, the study identifies overcrowding, multi-generational homestead composition, extreme poverty and unchecked mixed-usage of residential spaces as major challenges to effective social distancing (and self-isolation) in the Lohwol-Topp settlement in Rayfield, Jos South LGA of Plateau state, Nigeria. The study proposes firstly documentation and refined assessment of local overcrowding standards by professionals in the built environment in order to determine the extent in domestic situations as well as the standardisation of buildings using low cost materials of construction for health and well-being. The study also justifies the incorporation of possible isolation spaces in multi-generation homesteads for high risk residents in the layout of urban slum homesteads and the comprehensive documentation and monitoring of mixed use home based enterprises in urban slums which could hinder contact-tracing of random visitors.
{"title":"The Effect of Housing Conditions on Social Distancing During A Pandemic in Selected Urban Slums in North Central Nigeria","authors":"E. Enwerekowe, Ann Muopwun Katyen","doi":"10.7176/cer/12-7-04","DOIUrl":"https://doi.org/10.7176/cer/12-7-04","url":null,"abstract":"Social distancing is one of the prescribed means of preventing the spread of deadly diseases such as COVID-19. This study aims at examining how the concepts of social distancing and self-isolation are affected by housing spatial conditions among the urban poor which comprise a demographic exposed to community spread in less-than-standard housing conditions. Through a qualitative assessment of the problem which comprised theoretical reviews and field observations, the study identifies overcrowding, multi-generational homestead composition, extreme poverty and unchecked mixed-usage of residential spaces as major challenges to effective social distancing (and self-isolation) in the Lohwol-Topp settlement in Rayfield, Jos South LGA of Plateau state, Nigeria. The study proposes firstly documentation and refined assessment of local overcrowding standards by professionals in the built environment in order to determine the extent in domestic situations as well as the standardisation of buildings using low cost materials of construction for health and well-being. The study also justifies the incorporation of possible isolation spaces in multi-generation homesteads for high risk residents in the layout of urban slum homesteads and the comprehensive documentation and monitoring of mixed use home based enterprises in urban slums which could hinder contact-tracing of random visitors.","PeriodicalId":10219,"journal":{"name":"Civil and environmental research","volume":"29 6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79687893","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}
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