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Volume 14 (3S); 25 Sep, 2024 [Booklet] [ICCESR-2024]

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Research Paper

Mapping Buildings from Semi-Informal Settlements Using Non-Parametric Classifiers: A Case of Old Naledi

Mpoeleng W, Segobye M, Ouma Y, Moreri K, Manisa BM, Nkwae B, Maphale L and Nkhwanana N.

J. Civil Eng. Urban., 14(3s): 149-157, 2024; pii:S225204302400014-14

DOI: https://dx.doi.org/10.54203/jceu.2024.14

Abstract
Building footprints are essential for planning and designing new infrastructure like water reticulation, electricity transmission, sewer, and road networks. They are also necessary for delivery, census, and disaster management. It is therefore important to have up-to-date maps and GIS databases for service provision. However, mapping building of footprints in semi-informal settlements is problematic because of the spatial heterogeneity of settlements. This study evaluates three non-parametric machine learning algorithms for extracting building footprints from WorldView-2 (WV2) satellite imagery in a semi-informal settlement. WV2 satellite imagery data was fused with gray-level co-occurrence matrices (GLCM) to enhance building extraction. The algorithms used include the Gaussian Mixture Model (GMM), Random Forest (RF), and Support Vector Machine (SVM). The results indicate that GLCM does not improve the detection of buildings when using the GMM algorithm, but it increases building detection with RF and SVM. The GMM algorithm achieved the highest average accuracy of 92% for building detection. However, SVM and RF have an overall accuracy of 79% and 70% respectively. Though RF did not perform very well in identifying individual buildings, its overall accuracy was high. The outcome indicates that machine learning algorithms can adequately map building footprints from high-resolution satellite imagery.
Keywords: Building detection, WorldView-2, machine learning, Gray-Level Co-Occurrence Matrix (GLCM)

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Research Paper

Moment Gradient Factor Verification for Selected Monosymmetric Beams under Linear Moment Gradients

Mudenda K.

J. Civil Eng. Urban., 14(3s): 164-171, 2024; pii:S225204302400016-14

DOI: https://dx.doi.org/10.54203/jceu.2024.16

Abstract
The reuse of doubly symmetric beams by converting them into monosymmetric section beams offers some promising outcomes and has potential for mitigating carbon footprint of structures. However, due to their complexity monosymmetric sections must be used in a configuration that allows the monosymmetry effects to act beneficially. Although the South African design standard for hot-rolled steel does not provide any guidance on the design of monosymmetric beams, the Southern African steel construction handbook provides a formula for determining the critical elastic buckling moment for monosymmetric beams. This guidance implies that the moment gradient factor used for doubly symmetric sections can be used on monosymmetric sections as well. The aim of the study was to verify the validity of this approach of extending the moment gradient factor used for doubly symmetric beams to monosymmetric beams for two specific types of monosymmetric sections. It was found that although this approach appears to be justified for monosymmetric members in single curvature bending it may produce unconservative values of the critical buckling load in double curvature bending between restraint points. The level of un-conservatism also varies for different spans of the same member. This makes it difficult to specify a single moment modification factor value for these cases. The sensitivity in terms of load reduction observed for double curvature bending case was different for the two members examined with this attributed to differences in how the shear centre moves relative to the centroid. It is recommended that the critical buckling load for monosymmetric sections be determined on a case specific basis for members in double curvature from linear moment gradients. Under single curvature bending the moment gradient factor for doubly symmetric members appears to give acceptable predictions of the critical load.
Keywords: Steel beam, Monosymmetric, Lateral-torsional buckling, Moment gradient factor 

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Research Paper

Experiences Encountered while Using Construction Contracts during Project Delivery in Botswana

Ssegawa JK, Ntshwene K, and Kamaruddeen AM.

J. Civil Eng. Urban., 14(3s): 172-181, 2024; pii:S225204302400017-14

DOI: https://dx.doi.org/10.54203/jceu.2024.17

Abstract
Various forms of contracts guide the construction project delivery processes across the world. To make procurement more accessible and faster, various institutions have developed what is known as standard forms of contracts (SFoC). These institutions believe that SFoCs could be used in an adopted or adapted mode to reduce the burden of writing contracts every time a project is procured. This article discusses the results of a study that investigated the effectiveness of identified SFoCs and the experiences encountered by key stakeholders in using the contracts during construction project delivery. Study participants were drawn from contractor, consulting and client organisations and completed a questionnaire with both closed and open-ended questions. 11 attributes synthesised from literature were used to measure the effectiveness of a contract. Three major SFoCs were identified as being used in Botswana: the  Joint Contract Tribunal (JCT),  the New Engineering Contract (NEC) and International Federation of Consulting Engineers  (FIDIC). The FIDIC has a long history of use, but in recent years, the NEC entered the arena. Due to the low usage of the JCT, the discussion centred on the NEC and FIDIC contracts. Some insights were drawn from the study. Respondents did not find a big difference in the effectiveness of the two contracts (WME for NEC =3.3 and FIDIC =3.1). However, there were a few attributes for which the NEC seemed to be a better contract. These were a) simple and non-legalistic language with self-contained clauses and b) a communicative and proactive risk management regime, which respondents identified with a propensity to reduce or avoid disputes. The study had the limitations of having used a small (38) sample of respondents and the fact that NEC has not been used in the country for the length of time as the FIDIC contract.
Keywords: Construction contract, Standard forms of contract, Contract Administration, Construction industry, Botswana 

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Research Paper

Designing Ergonomic Safety Boots for Sustainable Construction in Botswana: A Case Study of Worker Foot Health
Botshabelo K, Sealetsa O, Setlhatlhanyo K. Moalosi R, Rapitsenyane Y, and Dichabeng P.

J. Civil Eng. Urban., 14(3s): 191-198, 2024; pii:S225204302400019-14

DOI: https://dx.doi.org/10.54203/jceu.2024.19

Abstract
The most essential asset in every construction work is the workers. In this regard, sustainability in construction must include and be centred on this vital resource. However, research indicates that civil engineers and construction workers often advocate for sustainability in infrastructural developments. This critical asset in construction often needs more consideration when people are engaged in construction work despite the many ergonomics challenges widely reported in the industry. This leads to workers in this industry being grossly afflicted by injuries such as musculoskeletal disorders, particularly of the foot. In addition, changes in global temperatures, attributed to global warming, situate civil engineers and construction workers, as they often work in open and challenging terrains, at risk of heat-related illnesses such as heat hyperpyrexia and heat exhaustion, which may also aggravate these musculoskeletal disorders conditions. However, it is pretty disturbing to notice that such illnesses are less investigated, particularly musculoskeletal disorders of the feet, which may be exasperated by the dire heat conditions noticeable in Botswana. This is because there is often a need for more knowledge and understanding of the risks associated with musculoskeletal disorders (MSDs). Furthermore, expertise in ergonomics is limited to assisting in the design of work as well as its conditions. This bequeaths both civil engineers and construction workers to operate under very challenging conditions despite pursuance of sustainability. Therefore, this case study investigated the prevalence of musculoskeletal disorders of the feet in the construction industry in Botswana with the purpose of designing a safety boot that matches the anthropometric measurements of the construction workers' feet. The research culminates in the design of a safety boot that is based on the workers' anthropometric measurements to prevent the occurrence of MSDs. The results of the study indicate that workers in this industry suffer from toe bunions, cons, toe deformities, smelly feet, etc. The study additionally indicates foot size differences across Botswana’s tribes. These differences may have severe implications for the use of safety boots and the development of ergonomics illnesses, mainly since the current safety boots used are imported from elsewhere with no modification to address the anthropometric feet measurements of Batswana. It is anticipated that the research will provide the necessary awareness that can help civil engineers explore sustainability not only from the context of infrastructural development (objects) but also from the perspective of workers (humans). This underscores the need for further research and action in this critical area.
Keywords: Construction Worker Ergonomics, Musculoskeletal Disorders, Safety Boot Design, Anthropometric Measurements, Heat-related Illnesses, Sustainable Construction Practices

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Research Paper

Effects of Resampled DEM on Watershed Characteristics and Prediction of Sediment Load in Oyun Watershed, Kwara, Nigeria

Adeogun AG, Mansur AW and Mohammed AA.

J. Civil Eng. Urban., 14(3s): 199-205, 2024; pii:S225204302400020-14

DOI: https://dx.doi.org/10.54203/jceu.2024.20

Abstract
Understanding the terrain and its impact on watershed characteristics, streamflow, and sediment loading is crucial for effective water resource management. This study investigates the influence of resampled Digital Elevation Models (DEM) on the prediction of watershed characteristics, streamflow, and sediment loading upstream of Oyun River Watershed, Nigeria. Various DEM resolutions, ranging from 30-meter to 90-meter, were analysed to assess their effects on hydrological predictions. To delineate the watershed, a DEM of 90-meter resolution was sourced from the space Shuttle Radar Topography Mission (SRTM), and the ASTER global DEM data sources. The 90-meter resolution was resampled to four different resolutions which are 75-meter, 60-meter, 45-meter, and 30-meter resolutions. The watershed and streamline were delineated, and the hydrologic simulation was performed using Soil and Water Assessment Tool (SWAT). The research findings revealed that changes in DEM resolution had a negligible impact on streamflow predictions within the Oyun River Watershed. However, a noticeable impact was observed in the prediction of sediment concentration. The 90-meter resolution DEM yielded the lowest predicted sediment concentration, measuring 2.28 mg/l, while the 30-meter resampled DEM produced the highest value at 5.21mg/l. Similarly, the sediment yield (SYLD t/ha) exhibited considerable variation across the different DEM resolutions, with the 90-meter DEM demonstrating the lowest value of approximately 528.90 t/ha, and the 30-meter DEM registering the highest at 2145.57 t/ha. Overall, this research highlights the necessity of careful DEM selection in hydrological modelling to ensure a comprehensive understanding of watershed dynamics, particularly in regions where sediment transport and water quality are of paramount concern.
Keywords: DEM, Hydrological Modelling, Nigeria, Sediment Loads, Watershed

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Research Paper

Stakeholders Influence on Construction Project Success

Mwakamui HK, Ntshwene K.

J. Civil Eng. Urban., 14(3s): 206-211, 2024; pii:S225204302400021-14

DOI: https://dx.doi.org/10.54203/jceu.2024.21

Abstract
For the past decade Botswana’s construction industry has been embroiled in a lot of controversies based on construction project constraints. These are characterized by construction project delays, budget overruns as well as scope creep and some of these construction projects have been deemed unsuccessful by different stakeholders. To find a mitigating factor for these problems, construction project constraints must be investigated beyond just the triple constraints to provide a solution for the Botswana construction industry. Therefore, the overall purpose of this study was to investigate how construction project constraints and stakeholders influence the outcome of a project. The study adopted a qualitative approach through face-to-face interviews with selected stakeholders such construction professionals, clients and other beneficiaries in the Gaborone and greater Gaborone areas. Thematic analysis was used to analyze data. The findings of the study established that the success of a construction project is subjective and is based on who is being asked, the construction professionals, the client and other beneficiaries had different perspectives on success of a project. The study revealed that initial constraints in a construction project tend to be carried along to the final stages of a construction project. However new few construction project constraints also emerge at the final stages of a construction project. The study found that stakeholders such as the client and other beneficiaries have a significant impact on construction projects due to their influence both positive and negative depending on the level of engagement.
Keywords: Factors of project success, Project constraints, Stakeholders, Triple constraints

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Review

Navigating Climate Change: A Review of Policies in Botswana, Africa, and Beyond

Makoba M, Chaba TL, and Ramontsho QJ.

J. Civil Eng. Urban., 14(3s): 220-228, 2024; pii:S225204302400023-14

DOI: https://dx.doi.org/10.54203/jceu.2024.23

Abstract
This paper is an insightful perspective analysis of Botswana climate change policies in an effort to establish their effectiveness in relation to regional and international initiatives. For a critical review of both mitigation and adaptation efforts by different countries, the effectiveness is analysed, including their strengths and inadequacies noted, and recommendations made towards enhancing policy coherence and effectiveness. It examines the steps Botswana and other countries have taken to cut greenhouse gas emissions, improve energy efficiency, support the use of renewable energy sources, and implement sustainable land management practices. The paper also delves into Botswana's efforts to build climate resilience, such as creating a National Adaptation Plan and incorporating climate considerations across various sectors.
Keywords: Climate change policies, Policy review, International agreements, Sustainable development, Botswana

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Research Paper

Flexible Vegetation Behavior under Varying Areal Densities and Effects on Flow Structures: Numerical Observations

Busari AO and John KA.

J. Civil Eng. Urban., 14(3s): 229-237, 2024; pii:S225204302400024-14

DOI: https://dx.doi.org/10.54203/jceu.2024.24

Abstract
This study carried out extensive numerical studies on a refined “One dimensional (1-D) Reynolds Averaging Navier-Stokes (RANS) Model” for vegetated open channel flow.  In the 1-D RANS model, the Spalart Allmaras closure model was used to model the turbulence caused by eddies within the vegetation zone and the interface between the top of the vegetation and the clear water zone. In this work, numerical simulations using 1-D RANS model are carried out using dataset obtained from the laboratory under different hydraulic conditions of varying areal vegetation densities. Three classes of highly flexible vegetation densities were simulated: low, medium and highly dense vegetation. The model predictions in terms of mean vertical stream-wise velocity profile and Reynolds Shear Stresses were compared with the laboratory flume experimental results. The 1-D RANS model performances were satisfactory for low and medium densities.  However, discrepancies were seen in the model prediction for highly dense vegetation. Hence, the hydraulic roughness parameters in the numerical model has been modified for model re-calibration to capture the position of zero-displacement of velocities. Using the modified parameters, the velocity profiles and the Reynolds Shear Stresses were predicted with very low uncertainty.
Keywords: Zero-displacement parameter, 1-D RANS model, Reynolds shear stresses, areal density, flexible vegetation

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Research Paper

Performance-Based Evaluation of Steel Fibre Reinforced Normal- and High-Strength Concretes Using Statistical Analysis of Experimental Database

Adewuyi AP, and Animbom O.

J. Civil Eng. Urban., 14(3s): 238-246, 2024; pii:S225204302400025-14

DOI: https://dx.doi.org/10.54203/jceu.2024.25

Abstract
The widespread acceptance of concrete can be attributed to its unique characteristics, despite inherent drawbacks such as brittleness and weak tensile strength. The study was aimed at evaluating the optimal content and characterization of steel fibres required to impede crack propagation and enhance overall strength of concrete. The influence of critical factors like fibre content, length, diameter, and volume fraction on the performance of steel fibre reinforced concretes (SFRC) through statistical analysis of 209 experimental data. The influence of these factors on the compressive, flexural, and tensile strengths of concrete was analyzed as a function of the mean and coefficient of variation of the normalized strength values. The study found that steel fibres in concrete produced success rates of 67.9% (7.1% average strength improvement = ASI) in compressive strength, 78.5% (38.2% ASI) in flexural strength and 84.2% (23.8% ASI) in tensile strength. The study further separately examined the impact of steel fibres on both normal strength concretes (NSC) and high strength concretes (HSC). The findings indicated an overall success rate of 60% (6.97% ASI), 69.9% (38.36% ASI), and 75.6% (23.59% ASI) for compressive, flexural, and split tensile strength, respectively, in NSC. However, higher degree of strength enhancement of 74.0% (7.16% ASI), 84.8% (39.21% ASI), and 86.6% (23.51% ASI) were recorded for compressive, flexural, and split tensile strength, respectively in HSC. The research underscores the effectiveness of incorporating steel fibres as a reinforcement strategy in enhancing various strength aspects of concrete.
Keywords: Fibre reinforced concrete, steel fibres, compressive strength, tensile strength, flexural strength, normalized strength, average strength improvement.

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Research Paper

Empirical Scrutiny of Geopolymer Concrete Containing Locally-produced Superplasticizer under Varied Temperatures

Agashua LO, Arum C, Oluyemi-Ayibiowu BD, and Ikumapayi CM.

J. Civil Eng. Urban., 14(3s): 247-262, 2024; pii:S225204302400026-14

DOI: https://dx.doi.org/10.54203/jceu.2024.26

Abstract
Cement manufacturing companies contribute greatly to carbon-dioxide emission during production, hence there is need for novel eco-friendly or biodegradable cementitious material, which has the same strength and also durable. Geopolymers which are eco-friendly waste materials, which can also reduce construction cost are therefore considered for this purpose. The geopolymer stabilizing materials, fly ash (FA), kaolin clays powder (KCP), rice husk ash (RHA), and alkaline activator (procured sodium silicate, waste-created sodium silicate and sodium hydroxide) were added at 0, 2.5, 5, 7.5, and 10%, to the naturally created superplasticizer geopolymer concrete (GPC), so as to solve the problem of workability and efflorescence associated with fly ash based GPC. FTIR results shows major absorbance band at the region between 950 and 3250 cm−1. It means that addition of the naturally made superplasticizer to the geopolymer concrete lowered the viscosity and increased the flow behavior of concrete. The geopolymer concrete consists of super plasticizer (1.5%) and optimum of various binders i.e. 5% FA + 7.5% KC + 10% RHA + aggregate + water. At temperature above 70°C both compressive strength and weight decreases, for naturally made and purchased sodium silicate. The optimal geopolymer product showed substantial strength and durability enhancements at 70°C temperatures, with strength and durability values decline above 70°C, indicating material deterioration. A positive correlation between hot-state temperature, strength and durability properties was also established. The R2 of the Feret on the test set reaches 0.967, indicating its excellent predictive performance.
Keywords: Rice Husk, Fourier Transform Infrared Spectroscopy, Waste-created sodium silicate, Superplasticizer; Eco-friendly

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Research Paper

An Analysis of Water Demand of the Rural Population within the Iishana System, Namibia

Junias E, Valentine KY, Afis BO, Pires EES, Johannes P, Fahrenberg M, Reinhardt CI, Jüpner R and Schulte A.

J. Civil Eng. Urban., 14(3s): 263-270, 2024; pii:S225204302400027-14

DOI: https://dx.doi.org/10.54203/jceu.2024.27

Abstract
The Namibian people, particularly, those living within the Iishana system, which is a subset of the Cuvelai Basin, often encounter recurrent floods and droughts. After each rainy season, the Iishana system dries up gradually, hence, water for both agriculture and potable purposes becomes crucial. With the anticipated new water infrastructural development and rehabilitation of existing ones, it will be necessary to ascertain the water demand of the rural population, for the quantification of the supply potential to improve water availability. This study adopts historical water consumption per capita recommended within the Iishana system to determine the rural population demand. Considering a thirty years’ population projection, the water demand of the Iishana system is properly estimated. Moreover, the historical hydrological dataset daily data for the period 2012-2021 was used for the analysis. The current demand is estimated at 2,479 cubic meters per day. The projections of water demand for the rural population for 2033, 2043, and 2053 are 0.9, 0.5, and 0.1 Mm3/year, respectively.  More so, the surface water resource potential of the system is estimated at an average of 300 mm/year. The region loses more water through evaporation than it receives in the wet season. Around 2500 mm of water evaporates from the surface annually, giving a water deficit of 2200 mm/year. The region's flat, shallow landscape, high evaporation rate, and the inadequacy of infrastructure have made the area vulnerable in terms of water security for both agricultural and potable purposes, resulting in droughts after the rainy season. With these findings, it is recommended to build water infrastructures within the region to improve the well-being and livelihood of rural communities.  
Keywords: Water demand, water supply, rural population, per capita demand, Iishana system, Namibia

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Proceedings of The International Conference on Civil Engineering for Sustainability and Resilience in the 21st Century and Beyond (ICCESR-2024)

University of Botswana, Gaborone, Botswana,

25–26 June, 2024

The International Conference on Civil Engineering for Sustainability and Resilience in the 21st Century and Beyond (ICCESR-2024), organized by the Department of Civil Engineering at the University of Botswana, brought together academia, practitioners, researchers, policy makers and regulators to discuss emerging and pertinent issues relating to sustainability and resilience in Civil Engineering and related disciplines. The conference thematic areas encompassed developments and improvements in innovative designs, construction and smart technologies and the formulation of appropriate policies in the face of climate change to ensure sustainability and resilience.

This Special Issue of the Journal of Civil Engineering and Urbanism is a compilation of the proceedings of the ICCESR-2024 conference.

Dr. Damilola Oyejobi

Secretary, ICCESR-2024 Organizing committee

https://conferences.ub.bw/index.php/ICCESR/ICCESR-2024

Guest Editors

Prof. Yashon Ouma
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Prof. Ssegawa, Joseph
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Dr. Damilola Oyewumi Oyejobi
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Dr. Ali A Firoozi
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana


Selected Reviewers

Prof. Mahongo Dithinde
Department of Civil Engineering, University of Botswana

Dr. Kealeboga Moreri
Department of Civil Engineering, University of Botswana

Dr. Adekunle Philips Adewuyi
Department of Civil Engineering, University of Botswana

Dr. Stephen A Alabi
Department of Civil Engineering, University of Botswana

Dr. Ajibola Ibrahim Quadri
Federal University of Technology, Akure, Ondo State, Nigeria

Mr. Lawrence Zahemen Tuleun
Department of Civil Engineering, University of Ilorin, Ilorin, Kwara State, Nigeria

Dr. Lopang Maphale
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Mr Nyaladzani Nkhwanana
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Engr. Abdulkadir Taofeeq Sholagberu
Department of Water Resources & Environmental Engineering, University of Ilorin, Ilorin, Nigeria

Dr. Nonso Izuchukwu Ewurum
Department of Architecture & Planning, University of Botswana, Gaborone, Botswana

Dr. Njideka Maryclara Aguome
Department of Architecture & Planning, University of Botswana, Gaborone, Botswana

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