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2019 Bi-Annual conference

Conference Papers

Below are the published paper for the 2019 Bi-Annual Conference

Abstruct

The new generation of geotechnical codes are developed on the basis of Limit State Design principles in accordance with Annex D of ISO 2394:2015. Limit state design philosophy requires verification through partial factors that the occurrence of both ultimate and serviceability limit states are sufficiently improbable. The first step in the calibration of the partial factors is the establishment of the target reliability index (βT). However, the unfortunate status quo is such that more emphasis is placed on the ultimate limit state.   Worldwide βT and the associated partial factors for ultimate limit state have been well studied and prescribed in codes of practice. In the South African loading code SANS 10160: 2011 which has also been adopted in Botswana and other SADC countries, βT for ultimate limit state has been set to 3.0.  To achieve consistency in design, it is imperative that concerted effort be devoted to establishing βT for serviceability limit state.   Accordingly this paper uses a Kondner-type hyperbolic load transfer function to derive the target reliability index for serviceability limit state implied in current pile foundations design practice.  The analysis is based on a pile load test database from the Southern African geological setting and pile design practice. The results of the analysis shows that Serviceability limit state reliability index implied in the current Southern African pile design range from 2.5 to 3.2.

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The California Bearing Ratio (CBR) is the most common empirical pavement design method worldwide.  In Botswana the CBR is used as the basis for (i) the structural design of road pavements using the catalogue approach, (ii) classifying the strength of the subgrades and (iii) classifying the quality of pavement construction materials. However the CBR does not measure any of the fundamental engineering properties of the soil that critically influence its performance. Furthermore the CBR test is time consuming as the specimen has to be soaked for four days before testing. It also requires a large quantity of materials and as hence relatively expensive. Accordingly there is concerted effort worldwide to correlate the CBR with simple, fast and cheap soil tests.   The objectives of this paper are (i) to investigate the strength and direction of the relationship between California Bearing ratio and Unconfined Compressive strength (UCS) and (ii) to predict the CBR values from UCS test results.  These objectives were achieved by performing correlation and regression analyses on CBR and UCS laboratory test results.  The results show that there is an appreciable negative correlation between the two parameters with a correlation coefficient of greater than 0.5. Furthermore, there are cases where the predicted CBR values are close to the actual measured values and thus implying that there is a potential for predicting CBR values from simple UCS laboratory tests results.

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Sand harvesting from rivers and open areas in Botswana has been taking place without effective monitoring resulting in visible damage to river banks and beds as well as leaving deep borrow pits that people and animals can fall in and sustain serious injuries. This has caused concern to citizens as well as government authorities responsible for regulating mining activities in the country.

The damage has led to perceived changes to physical features of water courses by widening them and subsequently interfering with the flow of water during rainy seasons. Farming activities along affected water courses such as watering livestock from wells dug in river beds as well as wild life that has been depending on green forage along river banks have been disrupted.

The use of crusher dust from stone quarries has been the target of investigations in the bid to save the rivers and open sand fields. Availability, suitability and cost effectiveness of using crusher dust is being scrutinized.

This paper has made recommendations to universally solve the sand problem while protecting the environment.

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The use of x-ray whole body scanners on human subjects for medical applications or to detect contraband seem to meet with universal approval. The intention to use it in the commercial work environment to search for precious commodities, introduces a different perception to the justification process. On the basis of these developments, it is important that the general public is succinctly informed about whole-body x-ray scanners so that they can weigh the pros and cons concerning advantages and disadvantages as well as possible consequences that may emanate from their use.

The aim of this paper is to provide basic scientific and technical information for any reader about exposure to what is regarded to be “low to very low” doses of ionizing radiation. It is intended to provide a platform for a debate that can guide readers to make informed decisions concerning non-medical exposure to penetrating x-rays.

Abstruct

The use of x-ray whole body scanners on human subjects for medical applications or to detect contraband seem to meet with universal approval. The intention to use it in the commercial work environment to search for precious commodities, introduces a different perception to the justification process. On the basis of these developments, it is important that the general public is succinctly informed about whole-body x-ray scanners so that they can weigh the pros and cons concerning advantages and disadvantages as well as possible consequences that may emanate from their use.

The aim of this paper is to provide basic scientific and technical information for any reader about exposure to what is regarded to be “low to very low” doses of ionizing radiation. It is intended to provide a platform for a debate that can guide readers to make informed decisions concerning non-medical exposure to penetrating x-rays.

Abstruct

The purpose of this paper is to design a geyser timer that is remotely controlled, display the status of the appliance in real time and then transmit this data to a monitoring and evaluation system for recording. The advantage is that energy consumers can control their appliance commitment thereby promote energy reduction and hence economic benefit to the consumer through the use of effective demand side management. This controller was also tested on other household appliances. This work mainly incorporated the use of Arduino and Global System for Mobile communication GSM.  Some of the major components include a driver circuit for controlling the geyser mainly through the use of a relay, and a phone screen display to indicate the status of the appliance and finally the GSM module sim900 with a phone that has a Subscriber Identity Module (SIM) card for sending and receiving commands. The advantage of this is the flexibility of the use of local sim card. The findings of the work were that appliances can be controlled using a mobile phone by way of using sms. The timer also worked efficiently in turning the appliances off or on after at any set time. Every time there was a change of control state of the appliance an sms notification is send to the receiver there by allowing for constant monitoring of the system.

Abstruct

The purpose of this paper is to design a geyser timer that is remotely controlled, display the status of the appliance in real time and then transmit this data to a monitoring and evaluation system for recording. The advantage is that energy consumers can control their appliance commitment thereby promote energy reduction and hence economic benefit to the consumer through the use of effective demand side management. This controller was also tested on other household appliances. This work mainly incorporated the use of Arduino and Global System for Mobile communication GSM.  Some of the major components include a driver circuit for controlling the geyser mainly through the use of a relay, and a phone screen display to indicate the status of the appliance and finally the GSM module sim900 with a phone that has a Subscriber Identity Module (SIM) card for sending and receiving commands. The advantage of this is the flexibility of the use of local sim card. The findings of the work were that appliances can be controlled using a mobile phone by way of using sms. The timer also worked efficiently in turning the appliances off or on after at any set time. Every time there was a change of control state of the appliance an sms notification is send to the receiver there by allowing for constant monitoring of the system.

Abstruct

Radon monitoring and Radon mapping is vital, especially, for countries where the Environmental Radioactivity levels are high. Such studies are of profound importance in countries like Botswana where large scale mining activities are involved. This is more so for Botswana where Uranium reserves are identified near Serule.   It is essential to know, before Uranium mining starts, the base levels of Radon and its progeny which are mainly responsible for human exposure that finally lead to increased Lung cancer incidents.  With a view to contribute to Radon monitoring data in the major cities of Botswana, experimental indoor Radon data has been collected in a house in Mahalapye village, Botswana and the results are presented.

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Sophisticated living and working standards together with reduced prices for air-conditioning units have significantly increased the demand for air-conditioning in Africa. Considering the importance of decoupling the electrical power load on the electric grid to avoid breakdowns in times of peak load, the use of solar-thermal energy for the air-conditioning of buildings carries a huge undeveloped potential. Solar Desiccant and Evaporative Cooling (DEC) air-conditioning provides a renewable alternative to the customarily employed technologies as it uses low temperature solar heat instead of electricity. The climate specific effectiveness of solar DEC-systems and relevant preferable adaptions of the system design have been predominantly analysed based on individual simulation for selected sites. In order to systematically deduce design-specific outline data for the application of the solar DEC-technology at climatically different sites a methodological zoning approach was developed. This paper presents a brief literature review of applied climate specific analyses of solar air-conditioning systems. Subsequently the developed methodology and the climate selection are described. The core of this paper describes a technology specific climate data analysis for the African sites of Maun (Botswana), Johannesburg (South Africa) and Cairo (Egypt). Consequently planning strategies regarding the site-specific effectiveness of solar DEC-systems as well as system designs for different African climates are discussed.

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Over the past few decades, the price of raw materials in the steel-making industry, such as aluminum, copper and zinc, increased significantly. Moreover, at the end of the 20th century and during the first decade of the 21st century a very volatile fluctuation of the price of nickel, an alloying element in austenitic stainless steels, was observed. This fluctuation in the price of nickel then posed very serious consequences for the general cost and hence affordability of austenitic stainless steels as materials of choice for various applications. It follows that this then lead to further explorations of other alternatives, which lead to an increased interest in ferritic stainless steels with added superior properties similar to those of the austenitic stainless steels. The ferritic 436 is one such stainless steel, which has over the years seen its use, ranging from house hold products to the more sophisticated automotive industry applications, increase significantly. This study sort to explore further these various properties of the ferritic 436 steel to better understand its emerging widespread use. The study sort to compare the effects of some heat-treatment processes of a sample of the material (transfer bar sample from the roughing mill) on the mechanical properties of the steel by comparing the effects of three different quenching methods and/or mediums on its morphology and hardness. These quenching mediums included quenching in water, quenching in an ice-cold medium at 0oC, as well as cooling in air. Most of these heat-treatment, according to literature, have the possible effect of allowing the material to recrystallize into a much more equiaxed grain morphology with possible smaller grain sizes, and hence better properties, amidst at different degrees and/or extends from one quenching medium to another. Although indications of this expected norm were observed to some extent, especially on the grain morphology, the hardness test results did not show any significant improvement in mechanical properties associated with the various quenching mediums. This however has been possibly linked to the quality of controlling the quenching medium environments, as well as the contribution of the temperature at which the material was austenitized prior to quenching (995oC), both of which have been proven in literature to also affect mechanical properties of steels.

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This study investigated and reported on factors contributing to construction cost in Botswana from the perspective of construction contractors operating in the country. Major problems (factors) facing the construction industry worldwide were captured from the literature review. These factors were the subject of ranking by the 16 construction contractors operating in the country and registered as grades D and E. These were purposively sampled as they are very few in the country. The results revealed that the five cost factors that ranked highest in descending order of contribution are construction management factors (0.668)), construction item factors (0.603), cost estimating factors (0.535), environmental factors (0.515) and financing factors (0.406). The five factor variables that ranked highest in descending order are: cost of materials (0.858), incorrect project planning, (0.806), frequent design changes (0.754), lack of coordination between designers and contractor (0.753), contract management (0.742). The main factor contributing to high cost of construction in Botswana is cost of materials. Government the major client of the construction industry in Botswana was advised to train manpower in construction management and embark on diversification policy that would reduce inflation to which the problem of high cost of construction materials could be traced.

Conference Photos

Conference Papers

Below are the published paper for the 2019 Bi-Annual Conference

Abstruct

The new generation of geotechnical codes are developed on the basis of Limit State Design principles in accordance with Annex D of ISO 2394:2015. Limit state design philosophy requires verification through partial factors that the occurrence of both ultimate and serviceability limit states are sufficiently improbable. The first step in the calibration of the partial factors is the establishment of the target reliability index (βT). However, the unfortunate status quo is such that more emphasis is placed on the ultimate limit state.   Worldwide βT and the associated partial factors for ultimate limit state have been well studied and prescribed in codes of practice. In the South African loading code SANS 10160: 2011 which has also been adopted in Botswana and other SADC countries, βT for ultimate limit state has been set to 3.0.  To achieve consistency in design, it is imperative that concerted effort be devoted to establishing βT for serviceability limit state.   Accordingly this paper uses a Kondner-type hyperbolic load transfer function to derive the target reliability index for serviceability limit state implied in current pile foundations design practice.  The analysis is based on a pile load test database from the Southern African geological setting and pile design practice. The results of the analysis shows that Serviceability limit state reliability index implied in the current Southern African pile design range from 2.5 to 3.2.

Abstruct

The new generation of geotechnical codes are developed on the basis of Limit State Design principles in accordance with Annex D of ISO 2394:2015. Limit state design philosophy requires verification through partial factors that the occurrence of both ultimate and serviceability limit states are sufficiently improbable. The first step in the calibration of the partial factors is the establishment of the target reliability index (βT). However, the unfortunate status quo is such that more emphasis is placed on the ultimate limit state.   Worldwide βT and the associated partial factors for ultimate limit state have been well studied and prescribed in codes of practice. In the South African loading code SANS 10160: 2011 which has also been adopted in Botswana and other SADC countries, βT for ultimate limit state has been set to 3.0.  To achieve consistency in design, it is imperative that concerted effort be devoted to establishing βT for serviceability limit state.   Accordingly this paper uses a Kondner-type hyperbolic load transfer function to derive the target reliability index for serviceability limit state implied in current pile foundations design practice.  The analysis is based on a pile load test database from the Southern African geological setting and pile design practice. The results of the analysis shows that Serviceability limit state reliability index implied in the current Southern African pile design range from 2.5 to 3.2.

About BIE

Botswana Institution of Engineers (BIE) is a professional institution consisting of engineers from all engineering disciplines. It was formed in 1983 by a group of engineers concerned about the development, practice and status of engineering in the country, particularly with regard to the importance of its contribution in national development. It was previously known as the Botswana Engineers Society but was changed in 1995 to Botswana Institution of Engineers, following a major review of its constitution.

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P.O. Box 40535 Gaborone, Botswana
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Email: info@bie.org.bw

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