J. Mahachi | Wits University (original) (raw)
Papers by J. Mahachi
CRC Press eBooks, Oct 30, 2023
The utilization of innovative building systems to address shortage of lowcost housing in South Af... more The utilization of innovative building systems to address shortage of lowcost housing in South Africa gained interest in recent years. However, low adoption rate of these systems is partly due to concerns surrounding their structural performance compared to conventional building systems. Determining reliable structural performance criteria is crucial to address this issue. This study aims to address this gap in literature by investigating the development of structural performance criteria for innovative building systems. The study employs both qualitative and quantitative research methods, including numerical simulations. Current building codes, regulations and unique challenges of various climatic conditions are considered. The results provide a critical evaluation of current knowledge on structural performance criteria for innovative building systems and identifies areas for improvement. The findings will contribute to developing updated criteria for assessing these systems, resulting in quality low-cost housing solutions and greater adoption rate.
South African Journal of Science
A house fulfils a fundamental need for human habitation. Acquisition of a house (through purchase... more A house fulfils a fundamental need for human habitation. Acquisition of a house (through purchase or construction) is probably one of the greatest expenses for most people in South Africa. However, the complex South African housing industry has two markets: one market financed by the private sector and the other subsidised by the government. Despite several measures put in place by the government, the housing backlog in South Africa is still unacceptably high, at more than 2.3 million houses. 1 Furthermore, in South Africa, there have been challenges of limited uptake of innovative building technologies in house construction. Fairclough 2 and Burger 3 have noted that innovations have changed how homes are made in many countries, their performance, affordability, and functionality. Although the South African regulatory environment is not prescriptive in the materials and products used in building construction, there has been a slow uptake of innovative building products compared to that in other countries. In this article, the term 'innovative building products' refers to any non-conventional building products that have been assessed and certified by Agrèment South Africa 4 (www.agrement.co.za). There are no South African National Standards to assess the performance of these products. The use of innovative building products in South Africa has important economic ramifications, including eradicating the housing backlog, providing better-quality housing and construction products, and possibly reducing the life cycle cost of the houses.
: t South Africa has come a long way in addressing the housing backlog for the poor and has even ... more : t South Africa has come a long way in addressing the housing backlog for the poor and has even taken further steps by providing a regulatory environment for energy efficient houses. The benefits of including energy efficiency are increasingly becoming realized, not only due to reduction in pollution but due to the additional electricity crisis affecting most South Africans. Many challenges, however, lie ahead with finding a balance between eradicating informal settlements and providing energy efficiency measures, taking into account the escalating cost of building materials. The South African regulatory environment provides for the implementation of innovative building technologies (IBT). However, the uptake of these IBTs to assist in fast delivery of houses and social infrastructure is very slow. The aim of this paper is to report on an investigation carried out on a few case studies where IBTs have been used in housing developments, by collating the data from the projects, analy...
Acta Structilia, 2021
Housing is a critical socioeconomic driver in the vast majority of developing countries, includin... more Housing is a critical socioeconomic driver in the vast majority of developing countries, including South Africa. It involves many aspects such as construction quality, affordability, geographic location, long-term financing, and the environment. A key research concern is the quantification of the construction quality of houses and how this may be used to assist in the delivery of better quality houses. This article is based on studies undertaken on housing construction sites in South Africa. A construction assessment tool is developed using principles similar to those used by CONQUAS in Singapore and Malaysia. The tool thus developed is capable of measuring the quality of 'as-built' construction elements of a house against national technical standards and specifications, within reasonable time and cost. Studies on the quality of houses were then conducted on 700 houses (two low-income projects and one middle-income project). The results showed that the two low-income projects had average quality scores of 58% and 64%, while the middle-income project scored 80%. Details of the sub-elements of the scores indicated the developmental needs of the contractors involved in the projects. Using the
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
This paper presents a review of the most relevant issues related to the structural and architectu... more This paper presents a review of the most relevant issues related to the structural and architectural design of large sport stadia, with the particular concern of wind loading aspects of these types of structures. The role and relevance of wind-tunnel tests of such facilities are highlighted. The paper summarises the wind engineering inputs in preparation for the 2010 FIFA World Cup tournament in South Africa however it is also relevant to the forthcoming 2012 European FIFA event in Poland and Ukraine.
Journal of the South African Institution of Civil Engineering
The current roof anchoring methods for houses in South Africa are described in the standard SANS ... more The current roof anchoring methods for houses in South Africa are described in the standard SANS 10400. The adequacy of these prescribed roof anchoring methods for low-income houses (LIHs) is questionable, due to several recently reported failures caused by strong winds. This study quantitively investigates the performance of the prescribed roof anchoring methods through numerical methods, and focuses on LIHs with light-weight roofs supported on single-leaf masonry walls. The masonry walls comprise either solid bricks or hollow cement blocks. The peak wind reaction forces that are expected to occur at the roof anchor systems were determined through a series of static analyses. Finite element analysis techniques were performed to predict the capacity of the roof anchor systems. The predicted resistance of the roof anchor systems was compared to the calculated peak wind reaction forces at the roof anchors to determine the adequacy of the roof anchor systems. The results of the researc...
With South Africa being one of the most water-scarce countries in the world, the limited water re... more With South Africa being one of the most water-scarce countries in the world, the limited water resources available must be well preserved and consciously utilized. Thepurpose of the research was to quantify the daily amount of groundwater pumpedout of the University's basement area, determining the impact that it has when discharged into the surrounding environment as well as the socioeconomic benefits it holds for the community and theUniversity. By analyzing data recorded from installed meters, it was determined that there was an average of 192.89m of groundwater extracted daily from March 2016 to February 2019. It was established that a total of 55.8% of this water was not utilised by the University and was discharged into the municipal stormwater system which was essentially wasted. Further investigations found that the installed meters did not account for all of the water flowing out of the basement area into the stormwater drain and that the amounts are greater than antici...
The impact of the COVID-19 pandemic has shown the lack of adequate housing and infrastructures ar... more The impact of the COVID-19 pandemic has shown the lack of adequate housing and infrastructures around the world The crisis has brought to light the fact that many countries do not have the means to offer adequate treatment medical centres for their population promptly According to the World Health Organisation (WHO), a COVID patient must be appropriately quarantined or isolated for treatment and this requires a comfortable and safe space to facilitate the speedy recovery of the patient However, most of the existing hospitals and clinics are built with concrete, timber, and steel (generally referred to as conventional building technologies), which take more time and sometimes costly to construct Fortunately, other methods can speed up the construction process and also offer an improved environment for the patient and other users in comparison to the conventional building technologies One such method is known as the non-conventional building technology, also known under various nomenc...
The current South African Code of Practic e for structural use of masonry uses four partial safet... more The current South African Code of Practic e for structural use of masonry uses four partial safety factors γm, for materials depending on construction control a nd quality control. With the boom in the construction industry, new entrants i the industry lack skills and the construction quality, particularly of masonry structures, is com promised. This has been proven by a number of structural failures and poor workmanship in the hom e building industry. However, the values of γm are based on the British Standards with some slight modifications to take into account local conditions. In this paper, focus is on establishing the reliability level as prescribed in the current code. The parametric calibration is based on curren t stochastic models and on statistical data collated by the National Home Building Registration Council (NHBRC) using a well researched quality assessment tool (Building Quality Index for Houses). Highlights are also made on the current work-in-progress in testing m...
The current methods for roof anchoring South African Low-Income Houses are described in the stand... more The current methods for roof anchoring South African Low-Income Houses are described in the standard SANS 10400. The adequacy of these prescribed roof anchoring methods is questionable due to several recently reported failures caused by strong winds. This study investigates the performance of the prescribed roof anchoring methods through quantitative research and numerical methods, and focuses on LIH with light-weight roofs supported on single leaf masonry walls. The masonry walls comprise of solid bricks. The peak wind reaction forces that are expected to occur at the roof anchor systems were determined through a series of static analyses. Finite Element Analysis techniques were then performed to predict the capacity of the roof anchor system. The results of the research suggest that LIHs prescribed roof anchor systems constructed from solid bricks perform poorly under the expected South African strong wind climate. This study suggests further research is required to develop adequa...
International Conference on Structural Engineering, Mechanics and Computation, Cape Town, 6-8 Sep... more International Conference on Structural Engineering, Mechanics and Computation, Cape Town, 6-8 September 2010
This paper presents a comparison investigation into analysis methods to determine the buckling ca... more This paper presents a comparison investigation into analysis methods to determine the buckling capacity of South African cold-formed steel lipped channel sections. The research considers the evaluation of buckling capacities of five different column lengths using five different methods: 1. experimental tests; 2. the Direct Strength Method (DSM) as prescribed in SANS 10162-2; 3. Eurocode 3; 4. simplified Finite Element Analysis (FEA), i.e. only beam modelling elements; and 5. finely refined FEA, i.e. plate modelling elements. All columns have a 75 x 50 x 20 x 2.0 (h x b x c x t mm) cold-formed lipped channel cross-section. A comparison of the experimental buckling results to the aforementioned methods shows that the Eurocode 3 and DSM buckling resistance values overestimate the buckling loads by 23.8% and 12.7%, respectively. For the two Finite Element Model (FEM) buckling analyses; the simplified FEA method yields an overestimation of 76.9% and the finely refined FEA yields an overe...
Materials Today: Proceedings
Abstract This paper presents the results of an experimental investigation carried out to assess t... more Abstract This paper presents the results of an experimental investigation carried out to assess the effect of some selected curing techniques on the compressive strength of concrete produced by partially replacing ordinary Portland cement (OPC) with Palm Oil Fuel Ashes (POFA) at percentage levels 0%, 10% and 15%. The influence of the POFA and the various curing techniques were evaluated by determining the compressive strength of the concrete produced. The results showed that the compressive strength of concrete increase as the percentage of POFA increases, and it also showed that the curing by immersion in water has the most effect on the strength of concrete.
Materials Today: Proceedings
CRC Press eBooks, Oct 30, 2023
The utilization of innovative building systems to address shortage of lowcost housing in South Af... more The utilization of innovative building systems to address shortage of lowcost housing in South Africa gained interest in recent years. However, low adoption rate of these systems is partly due to concerns surrounding their structural performance compared to conventional building systems. Determining reliable structural performance criteria is crucial to address this issue. This study aims to address this gap in literature by investigating the development of structural performance criteria for innovative building systems. The study employs both qualitative and quantitative research methods, including numerical simulations. Current building codes, regulations and unique challenges of various climatic conditions are considered. The results provide a critical evaluation of current knowledge on structural performance criteria for innovative building systems and identifies areas for improvement. The findings will contribute to developing updated criteria for assessing these systems, resulting in quality low-cost housing solutions and greater adoption rate.
South African Journal of Science
A house fulfils a fundamental need for human habitation. Acquisition of a house (through purchase... more A house fulfils a fundamental need for human habitation. Acquisition of a house (through purchase or construction) is probably one of the greatest expenses for most people in South Africa. However, the complex South African housing industry has two markets: one market financed by the private sector and the other subsidised by the government. Despite several measures put in place by the government, the housing backlog in South Africa is still unacceptably high, at more than 2.3 million houses. 1 Furthermore, in South Africa, there have been challenges of limited uptake of innovative building technologies in house construction. Fairclough 2 and Burger 3 have noted that innovations have changed how homes are made in many countries, their performance, affordability, and functionality. Although the South African regulatory environment is not prescriptive in the materials and products used in building construction, there has been a slow uptake of innovative building products compared to that in other countries. In this article, the term 'innovative building products' refers to any non-conventional building products that have been assessed and certified by Agrèment South Africa 4 (www.agrement.co.za). There are no South African National Standards to assess the performance of these products. The use of innovative building products in South Africa has important economic ramifications, including eradicating the housing backlog, providing better-quality housing and construction products, and possibly reducing the life cycle cost of the houses.
: t South Africa has come a long way in addressing the housing backlog for the poor and has even ... more : t South Africa has come a long way in addressing the housing backlog for the poor and has even taken further steps by providing a regulatory environment for energy efficient houses. The benefits of including energy efficiency are increasingly becoming realized, not only due to reduction in pollution but due to the additional electricity crisis affecting most South Africans. Many challenges, however, lie ahead with finding a balance between eradicating informal settlements and providing energy efficiency measures, taking into account the escalating cost of building materials. The South African regulatory environment provides for the implementation of innovative building technologies (IBT). However, the uptake of these IBTs to assist in fast delivery of houses and social infrastructure is very slow. The aim of this paper is to report on an investigation carried out on a few case studies where IBTs have been used in housing developments, by collating the data from the projects, analy...
Acta Structilia, 2021
Housing is a critical socioeconomic driver in the vast majority of developing countries, includin... more Housing is a critical socioeconomic driver in the vast majority of developing countries, including South Africa. It involves many aspects such as construction quality, affordability, geographic location, long-term financing, and the environment. A key research concern is the quantification of the construction quality of houses and how this may be used to assist in the delivery of better quality houses. This article is based on studies undertaken on housing construction sites in South Africa. A construction assessment tool is developed using principles similar to those used by CONQUAS in Singapore and Malaysia. The tool thus developed is capable of measuring the quality of 'as-built' construction elements of a house against national technical standards and specifications, within reasonable time and cost. Studies on the quality of houses were then conducted on 700 houses (two low-income projects and one middle-income project). The results showed that the two low-income projects had average quality scores of 58% and 64%, while the middle-income project scored 80%. Details of the sub-elements of the scores indicated the developmental needs of the contractors involved in the projects. Using the
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, Aug 23, 2022
This paper presents a review of the most relevant issues related to the structural and architectu... more This paper presents a review of the most relevant issues related to the structural and architectural design of large sport stadia, with the particular concern of wind loading aspects of these types of structures. The role and relevance of wind-tunnel tests of such facilities are highlighted. The paper summarises the wind engineering inputs in preparation for the 2010 FIFA World Cup tournament in South Africa however it is also relevant to the forthcoming 2012 European FIFA event in Poland and Ukraine.
Journal of the South African Institution of Civil Engineering
The current roof anchoring methods for houses in South Africa are described in the standard SANS ... more The current roof anchoring methods for houses in South Africa are described in the standard SANS 10400. The adequacy of these prescribed roof anchoring methods for low-income houses (LIHs) is questionable, due to several recently reported failures caused by strong winds. This study quantitively investigates the performance of the prescribed roof anchoring methods through numerical methods, and focuses on LIHs with light-weight roofs supported on single-leaf masonry walls. The masonry walls comprise either solid bricks or hollow cement blocks. The peak wind reaction forces that are expected to occur at the roof anchor systems were determined through a series of static analyses. Finite element analysis techniques were performed to predict the capacity of the roof anchor systems. The predicted resistance of the roof anchor systems was compared to the calculated peak wind reaction forces at the roof anchors to determine the adequacy of the roof anchor systems. The results of the researc...
With South Africa being one of the most water-scarce countries in the world, the limited water re... more With South Africa being one of the most water-scarce countries in the world, the limited water resources available must be well preserved and consciously utilized. Thepurpose of the research was to quantify the daily amount of groundwater pumpedout of the University's basement area, determining the impact that it has when discharged into the surrounding environment as well as the socioeconomic benefits it holds for the community and theUniversity. By analyzing data recorded from installed meters, it was determined that there was an average of 192.89m of groundwater extracted daily from March 2016 to February 2019. It was established that a total of 55.8% of this water was not utilised by the University and was discharged into the municipal stormwater system which was essentially wasted. Further investigations found that the installed meters did not account for all of the water flowing out of the basement area into the stormwater drain and that the amounts are greater than antici...
The impact of the COVID-19 pandemic has shown the lack of adequate housing and infrastructures ar... more The impact of the COVID-19 pandemic has shown the lack of adequate housing and infrastructures around the world The crisis has brought to light the fact that many countries do not have the means to offer adequate treatment medical centres for their population promptly According to the World Health Organisation (WHO), a COVID patient must be appropriately quarantined or isolated for treatment and this requires a comfortable and safe space to facilitate the speedy recovery of the patient However, most of the existing hospitals and clinics are built with concrete, timber, and steel (generally referred to as conventional building technologies), which take more time and sometimes costly to construct Fortunately, other methods can speed up the construction process and also offer an improved environment for the patient and other users in comparison to the conventional building technologies One such method is known as the non-conventional building technology, also known under various nomenc...
The current South African Code of Practic e for structural use of masonry uses four partial safet... more The current South African Code of Practic e for structural use of masonry uses four partial safety factors γm, for materials depending on construction control a nd quality control. With the boom in the construction industry, new entrants i the industry lack skills and the construction quality, particularly of masonry structures, is com promised. This has been proven by a number of structural failures and poor workmanship in the hom e building industry. However, the values of γm are based on the British Standards with some slight modifications to take into account local conditions. In this paper, focus is on establishing the reliability level as prescribed in the current code. The parametric calibration is based on curren t stochastic models and on statistical data collated by the National Home Building Registration Council (NHBRC) using a well researched quality assessment tool (Building Quality Index for Houses). Highlights are also made on the current work-in-progress in testing m...
The current methods for roof anchoring South African Low-Income Houses are described in the stand... more The current methods for roof anchoring South African Low-Income Houses are described in the standard SANS 10400. The adequacy of these prescribed roof anchoring methods is questionable due to several recently reported failures caused by strong winds. This study investigates the performance of the prescribed roof anchoring methods through quantitative research and numerical methods, and focuses on LIH with light-weight roofs supported on single leaf masonry walls. The masonry walls comprise of solid bricks. The peak wind reaction forces that are expected to occur at the roof anchor systems were determined through a series of static analyses. Finite Element Analysis techniques were then performed to predict the capacity of the roof anchor system. The results of the research suggest that LIHs prescribed roof anchor systems constructed from solid bricks perform poorly under the expected South African strong wind climate. This study suggests further research is required to develop adequa...
International Conference on Structural Engineering, Mechanics and Computation, Cape Town, 6-8 Sep... more International Conference on Structural Engineering, Mechanics and Computation, Cape Town, 6-8 September 2010
This paper presents a comparison investigation into analysis methods to determine the buckling ca... more This paper presents a comparison investigation into analysis methods to determine the buckling capacity of South African cold-formed steel lipped channel sections. The research considers the evaluation of buckling capacities of five different column lengths using five different methods: 1. experimental tests; 2. the Direct Strength Method (DSM) as prescribed in SANS 10162-2; 3. Eurocode 3; 4. simplified Finite Element Analysis (FEA), i.e. only beam modelling elements; and 5. finely refined FEA, i.e. plate modelling elements. All columns have a 75 x 50 x 20 x 2.0 (h x b x c x t mm) cold-formed lipped channel cross-section. A comparison of the experimental buckling results to the aforementioned methods shows that the Eurocode 3 and DSM buckling resistance values overestimate the buckling loads by 23.8% and 12.7%, respectively. For the two Finite Element Model (FEM) buckling analyses; the simplified FEA method yields an overestimation of 76.9% and the finely refined FEA yields an overe...
Materials Today: Proceedings
Abstract This paper presents the results of an experimental investigation carried out to assess t... more Abstract This paper presents the results of an experimental investigation carried out to assess the effect of some selected curing techniques on the compressive strength of concrete produced by partially replacing ordinary Portland cement (OPC) with Palm Oil Fuel Ashes (POFA) at percentage levels 0%, 10% and 15%. The influence of the POFA and the various curing techniques were evaluated by determining the compressive strength of the concrete produced. The results showed that the compressive strength of concrete increase as the percentage of POFA increases, and it also showed that the curing by immersion in water has the most effect on the strength of concrete.
Materials Today: Proceedings