Pub Date : 2022-03-25DOI: 10.17159/2309-8775/2022/v64no1a4
R. Juala, Y. Ballim, J. Mulopo
This paper reports on the possible use of sewage sludge ash as a pozzolanic supplementary cementitious material to Portland cement. Samples of sewage sludge were incinerated at 700°C, 800°C and 900°C and these were then cooled in the furnace (FISSA), in air (AISSA) or by quenching in water. The resulting ashes were ground to suitable fineness and used to prepare cement pastes and mortars in which the binder consisted of 30% ash and 70% Portland cement. The paste samples were used for microscopic and chemical assessment of the evolution of hydration products, while the mortars were used to assess the effects of the ashes on workability and compressive strength of laboratory-prepared samples using a water/binder ratio of 0.5. Fly ash was used as a reference pozzolanic material to assess the performance of sewage sludge ashes. Analysis of the sewage sludge ashes showed the presence of cementitious compounds and hydration products that suggest that this material can be used as a partial replacement of Portland cement. However, sewage sludge ash reduces the workability of the mortar. Compressive strength results indicate that the highest strength is obtained when the sewage sludge is incinerated at 900°C and then quenched in water.
{"title":"Assessment of local sewage sludge ash as a supplementary cementitious material - effects of incineration temperature and cooling rate of the ash","authors":"R. Juala, Y. Ballim, J. Mulopo","doi":"10.17159/2309-8775/2022/v64no1a4","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64no1a4","url":null,"abstract":"This paper reports on the possible use of sewage sludge ash as a pozzolanic supplementary cementitious material to Portland cement. Samples of sewage sludge were incinerated at 700°C, 800°C and 900°C and these were then cooled in the furnace (FISSA), in air (AISSA) or by quenching in water. The resulting ashes were ground to suitable fineness and used to prepare cement pastes and mortars in which the binder consisted of 30% ash and 70% Portland cement. The paste samples were used for microscopic and chemical assessment of the evolution of hydration products, while the mortars were used to assess the effects of the ashes on workability and compressive strength of laboratory-prepared samples using a water/binder ratio of 0.5. Fly ash was used as a reference pozzolanic material to assess the performance of sewage sludge ashes. Analysis of the sewage sludge ashes showed the presence of cementitious compounds and hydration products that suggest that this material can be used as a partial replacement of Portland cement. However, sewage sludge ash reduces the workability of the mortar. Compressive strength results indicate that the highest strength is obtained when the sewage sludge is incinerated at 900°C and then quenched in water.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45749244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-25DOI: 10.17159/2309-8775/2022/v64no1a6
Y. Wang, L. Wang, L. Sun
This paper investigates the occurrence and severity of collisions involving multiple vehicles on mountain expressways (MMEs) in Western China. A total of 1 521 crash samples occurring on one typical mountain expressway in Shaanxi, China, between 2012 and 2017, were analysed through a partially constrained generalised ordered logit to identify the significant risk factors contributing to the severity of such crashes. Elasticity analysis was performed to quantify the effects of each independent explanatory variable on the collision severity outcomes. Fourteen total explanatory variables were found to have a significant and pronounced influence on the likelihood of MME crashes. These include the type of collision, the at-fault driver's age, driving while fatigued, cell phone use while driving, alcohol-impaired driving, speeding, risky following and dangerous overtaking behaviour, sharp curves in the roadway and slippery pavement conditions, seasons, day of the week, time of day, and adverse weather (rain/snow/fog). The impacts of the variables on the collision severity were also explored. Taken together, the findings may serve as a useful guide for developing legislation and technical countermeasures to ensure traffic safety on mountain expressways in Western China.
{"title":"What leads to severe multi-vehicle crashes on mountainous expressways in Western China?","authors":"Y. Wang, L. Wang, L. Sun","doi":"10.17159/2309-8775/2022/v64no1a6","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64no1a6","url":null,"abstract":"This paper investigates the occurrence and severity of collisions involving multiple vehicles on mountain expressways (MMEs) in Western China. A total of 1 521 crash samples occurring on one typical mountain expressway in Shaanxi, China, between 2012 and 2017, were analysed through a partially constrained generalised ordered logit to identify the significant risk factors contributing to the severity of such crashes. Elasticity analysis was performed to quantify the effects of each independent explanatory variable on the collision severity outcomes. Fourteen total explanatory variables were found to have a significant and pronounced influence on the likelihood of MME crashes. These include the type of collision, the at-fault driver's age, driving while fatigued, cell phone use while driving, alcohol-impaired driving, speeding, risky following and dangerous overtaking behaviour, sharp curves in the roadway and slippery pavement conditions, seasons, day of the week, time of day, and adverse weather (rain/snow/fog). The impacts of the variables on the collision severity were also explored. Taken together, the findings may serve as a useful guide for developing legislation and technical countermeasures to ensure traffic safety on mountain expressways in Western China.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48549370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-25DOI: 10.17159/2309-8775/2022/v64n1a1
G. Fanourakis
Various pedological soil classification systems exist worldwide, including an internationally accepted system and various national systems, many of which have been incorporated into databases that include maps. Various physical and chemical soil properties are used for classifying soils according to these pedological systems. This paper proposes an approach which may be used to determine the engineering properties of soils from the physical and chemical properties that are used to pedologically classify soils by systems, and, in particular, the South African Binomial System. These engineering properties include the USCS and AASHTO classification groups which may, in turn, be used as a means of rapidly determining the general suitability of areas for proposed development, particularly during the reconnaissance investigation stages of transportation route locations and township developments, with a resultant saving of time and money. The model was verified using data from the study area, as well as from an area located approximately 190 km from the study area. A total of 88% of the classification groups determined by the model, in the study area, were correct. Furthermore, only 6% of the classifications were incorrect by a maximum of two groups. The classifications determined for the soils outside the study area were all correct.
{"title":"A mathematical model for determining engineering soil classifications from pedological data","authors":"G. Fanourakis","doi":"10.17159/2309-8775/2022/v64n1a1","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64n1a1","url":null,"abstract":"Various pedological soil classification systems exist worldwide, including an internationally accepted system and various national systems, many of which have been incorporated into databases that include maps. Various physical and chemical soil properties are used for classifying soils according to these pedological systems. This paper proposes an approach which may be used to determine the engineering properties of soils from the physical and chemical properties that are used to pedologically classify soils by systems, and, in particular, the South African Binomial System. These engineering properties include the USCS and AASHTO classification groups which may, in turn, be used as a means of rapidly determining the general suitability of areas for proposed development, particularly during the reconnaissance investigation stages of transportation route locations and township developments, with a resultant saving of time and money. The model was verified using data from the study area, as well as from an area located approximately 190 km from the study area. A total of 88% of the classification groups determined by the model, in the study area, were correct. Furthermore, only 6% of the classifications were incorrect by a maximum of two groups. The classifications determined for the soils outside the study area were all correct.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43974600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-25DOI: 10.17159/2309-8775/2022/v64no1a5
S. Hossell, C. Roth
The pseudo-dynamic experimentation technique was investigated to evaluate the damage occurring in a reinforced concrete footing with stub column due to the overall response of a linear elastic two-storey, two-bay moment-resisting steel frame structure that is subjected to an earthquake excitation with increasing peak ground acceleration. The implicit Newmark's method with static condensation was utilised in the present study to solve the governing equation of motion of the multi-degree-of-freedom system. Five pseudo-dynamic experiments were performed by scaling the El Centro ground motion record, which occurred in California on 18 May 1940, to produce peak ground accelerations that ranged between 0.34 g and 2 g. All the laboratory experiments were undertaken under a constant axial load for the duration of the applied earthquake excitation, and utilised Rayleigh damping to model the energy loss within the overall structure. The pseudo-dynamic method provides a reliable method to relate damage suffered by the stub column due to the overall structure's response to the applied earthquake excitation. The method enables the structural capacity and failure mechanisms of the reinforced concrete stub column to be observed in relation to the seismic demand. The hysteretic response of the stub columns and energy dissipation characteristics were determined, and it was shown that the yield strength of the longitudinal reinforcement within the stub column has a significant impact on the maximum shear capacity and damage incurred by the stub column. The damage is more pronounced with an increase in the number of cycles of vibration, particularly at displacements that exceed the yield strength of the reinforcement. An increase in the hysteretic energy dissipated by the reinforced concrete stub column results in a concomitant increase in the observed damage to the stub column in the form of concrete cracking, reinforcement yielding and spalling of the concrete.
{"title":"Evaluation of the seismic response of a reinforced concrete footing with stub column to increasing peak ground acceleration using pseudo-dynamic experimentation","authors":"S. Hossell, C. Roth","doi":"10.17159/2309-8775/2022/v64no1a5","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64no1a5","url":null,"abstract":"The pseudo-dynamic experimentation technique was investigated to evaluate the damage occurring in a reinforced concrete footing with stub column due to the overall response of a linear elastic two-storey, two-bay moment-resisting steel frame structure that is subjected to an earthquake excitation with increasing peak ground acceleration. The implicit Newmark's method with static condensation was utilised in the present study to solve the governing equation of motion of the multi-degree-of-freedom system. Five pseudo-dynamic experiments were performed by scaling the El Centro ground motion record, which occurred in California on 18 May 1940, to produce peak ground accelerations that ranged between 0.34 g and 2 g. All the laboratory experiments were undertaken under a constant axial load for the duration of the applied earthquake excitation, and utilised Rayleigh damping to model the energy loss within the overall structure. The pseudo-dynamic method provides a reliable method to relate damage suffered by the stub column due to the overall structure's response to the applied earthquake excitation. The method enables the structural capacity and failure mechanisms of the reinforced concrete stub column to be observed in relation to the seismic demand. The hysteretic response of the stub columns and energy dissipation characteristics were determined, and it was shown that the yield strength of the longitudinal reinforcement within the stub column has a significant impact on the maximum shear capacity and damage incurred by the stub column. The damage is more pronounced with an increase in the number of cycles of vibration, particularly at displacements that exceed the yield strength of the reinforcement. An increase in the hysteretic energy dissipated by the reinforced concrete stub column results in a concomitant increase in the observed damage to the stub column in the form of concrete cracking, reinforcement yielding and spalling of the concrete.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42375761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-25DOI: 10.17159/2309-8775/2022/v64no1a3
F. P. Bakker, N. de Koker, C. Viljoen
The South African wind loading standard SANS 10160-3:2019 recently adopted an improved map of characteristic basic wind speeds and increased the wind loading partial safety factor from 1.3 to 1.6. These changes represent an overhaul of the design wind loads throughout South Africa and were the result of several studies on the wind loading standard. Since these studies were conducted, substantially more wind speed data has been made available. This investigation aimed to use this data to assess the current design loads by estimating location-specific design values that maintain the current reliability level of the standard. A statistical test was developed to assess whether the design values in SANS 10160-3:2019 could be supported by the new data. It was found that several updates could be considered. These were incorporated into a new recommended map of basic wind speeds that could be considered for inclusion in the next revision of SANS 10160-3.
{"title":"Incorporation of additional information into the South African Wind Load Formulation","authors":"F. P. Bakker, N. de Koker, C. Viljoen","doi":"10.17159/2309-8775/2022/v64no1a3","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64no1a3","url":null,"abstract":"The South African wind loading standard SANS 10160-3:2019 recently adopted an improved map of characteristic basic wind speeds and increased the wind loading partial safety factor from 1.3 to 1.6. These changes represent an overhaul of the design wind loads throughout South Africa and were the result of several studies on the wind loading standard. Since these studies were conducted, substantially more wind speed data has been made available. This investigation aimed to use this data to assess the current design loads by estimating location-specific design values that maintain the current reliability level of the standard. A statistical test was developed to assess whether the design values in SANS 10160-3:2019 could be supported by the new data. It was found that several updates could be considered. These were incorporated into a new recommended map of basic wind speeds that could be considered for inclusion in the next revision of SANS 10160-3.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45408427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-25DOI: 10.17159/2309-8775/2022/v64n1a2
G. Fanourakis
In South Africa, a Land Type Survey (LTSS) has been conducted of the entire country. The information available from the LTSS is readily and inexpensively made available to the public (in the form of maps and accompanying memoirs). This survey includes information on the climate, terrain and soils. The soil information given includes qualitative data (such as pedological classifications, soil profiles and soil types), as well as quantitative physical and chemical properties of representative soils tested. Such information is used primarily for agricultural purposes. This paper proposes an approach for inferring information, of relevance in reconnaissance geotechnical engineering surveys, from Land Type data, to supplement geotechnical investigation data. The proposed procedure was verified using actual information from a geotechnical report. This investigation indicated that general engineering properties can be inferred from qualitative pedological data. In addition, statistically significant engineering properties (including the grading, Atterberg Limits and the USCS and AASHTO classifications) were determined from quantitative pedological data, in 86% of cases, for the soils considered. It is evident from this research that data from the Land Type survey data can be successfully used for geotechnical investigation purposes for certain developments (such as roads and townships) where the depth of interest is relatively shallow.
{"title":"Utilising Land Type data for geotechnical investigations","authors":"G. Fanourakis","doi":"10.17159/2309-8775/2022/v64n1a2","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64n1a2","url":null,"abstract":"In South Africa, a Land Type Survey (LTSS) has been conducted of the entire country. The information available from the LTSS is readily and inexpensively made available to the public (in the form of maps and accompanying memoirs). This survey includes information on the climate, terrain and soils. The soil information given includes qualitative data (such as pedological classifications, soil profiles and soil types), as well as quantitative physical and chemical properties of representative soils tested. Such information is used primarily for agricultural purposes. This paper proposes an approach for inferring information, of relevance in reconnaissance geotechnical engineering surveys, from Land Type data, to supplement geotechnical investigation data. The proposed procedure was verified using actual information from a geotechnical report. This investigation indicated that general engineering properties can be inferred from qualitative pedological data. In addition, statistically significant engineering properties (including the grading, Atterberg Limits and the USCS and AASHTO classifications) were determined from quantitative pedological data, in 86% of cases, for the soils considered. It is evident from this research that data from the Land Type survey data can be successfully used for geotechnical investigation purposes for certain developments (such as roads and townships) where the depth of interest is relatively shallow.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47651627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-31DOI: 10.17159/2309-8775/2021/v63n4a2
R. Marsh, A. Brent, I. D. De Kock
The construction industry is one of the largest consumers of natural resources. Improving the sustainability of construction industry activities is therefore key to mitigating the negative impact of the industry on the environment. Given the extent of the environmental challenges faced by many countries, the transition towards the adoption of sustainable alternatives in the construction industry must include dimensions of changing human behaviour. These dimensions include influencing the capability, opportunity, and motivation to adopt the desired change in behaviour. In order to improve the adoption and implementation of sustainable practices within the construction industry, the behaviour change processes of stakeholders need to be considered. This study describes how the Capability, Opportunity, Motivation-Behaviour (COM-B) model and Theoretical Domains Framework (TDF) were used to identify the barriers to and drivers of sustainable construction practices by construction industry stakeholders. The study included a structured questionnaire survey completed by 108 construction industry stakeholders and indicated a need to improve the capability, opportunity, and motivation amongst construction industry stakeholders to facilitate the adoption of sustainable construction practices. The questionnaire identified that an increase in the awareness, knowledge, interest, and demand for sustainable construction will facilitate the adoption thereof. Additionally, providing training and access to education on best practices for sustainability can positively influence the behaviour of stakeholders and improve their confidence in implementing sustainable construction practices. Economic factors such as the cost of implementing sustainable solutions and the perception of the economic and social benefits of sustainable construction were identified as the critical barriers. These barriers and drivers are mapped to five TDF domains (knowledge, skills, social influences, beliefs about capabilities, and beliefs about consequences), which can be targeted for behaviour change amongst construction industry stakeholders in future interventions.
{"title":"Understanding the barriers and drivers of sustainable construction adoption and implementation in South Africa: A quantitative study using the Theoretical Domains Framework and CQM-B model","authors":"R. Marsh, A. Brent, I. D. De Kock","doi":"10.17159/2309-8775/2021/v63n4a2","DOIUrl":"https://doi.org/10.17159/2309-8775/2021/v63n4a2","url":null,"abstract":"The construction industry is one of the largest consumers of natural resources. Improving the sustainability of construction industry activities is therefore key to mitigating the negative impact of the industry on the environment. Given the extent of the environmental challenges faced by many countries, the transition towards the adoption of sustainable alternatives in the construction industry must include dimensions of changing human behaviour. These dimensions include influencing the capability, opportunity, and motivation to adopt the desired change in behaviour. In order to improve the adoption and implementation of sustainable practices within the construction industry, the behaviour change processes of stakeholders need to be considered. This study describes how the Capability, Opportunity, Motivation-Behaviour (COM-B) model and Theoretical Domains Framework (TDF) were used to identify the barriers to and drivers of sustainable construction practices by construction industry stakeholders. The study included a structured questionnaire survey completed by 108 construction industry stakeholders and indicated a need to improve the capability, opportunity, and motivation amongst construction industry stakeholders to facilitate the adoption of sustainable construction practices. The questionnaire identified that an increase in the awareness, knowledge, interest, and demand for sustainable construction will facilitate the adoption thereof. Additionally, providing training and access to education on best practices for sustainability can positively influence the behaviour of stakeholders and improve their confidence in implementing sustainable construction practices. Economic factors such as the cost of implementing sustainable solutions and the perception of the economic and social benefits of sustainable construction were identified as the critical barriers. These barriers and drivers are mapped to five TDF domains (knowledge, skills, social influences, beliefs about capabilities, and beliefs about consequences), which can be targeted for behaviour change amongst construction industry stakeholders in future interventions.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42801877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-31DOI: 10.17159/2309-8775/2021/v63n4a3
R. van der Merwe, Jeffrey Mahachi
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 research suggest that, for LIHs constructed from solid bricks, the prescribed roof anchor systems perform poorly under the expected South African strong wind climate. The results indicated that the roof anchors will pull out at peak basic wind speeds of between 27 m/s and 32 m/s, and cracks will develop in the masonry prior to anchor pull-out. This study suggests that further research is required to develop adequate roof anchoring methods for LIHs with light-weight roofs, supported on solid brick walls, and that the relevant codes should be amended accordingly. Furthermore, the results showed that the prescribed roof anchor systems for LIHs constructed from hollow blocks performed well and were able to withstand the expected wind loads under the South African strong wind climate.
{"title":"An investigation of South African low-income housing roof anchor systems","authors":"R. van der Merwe, Jeffrey Mahachi","doi":"10.17159/2309-8775/2021/v63n4a3","DOIUrl":"https://doi.org/10.17159/2309-8775/2021/v63n4a3","url":null,"abstract":"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 research suggest that, for LIHs constructed from solid bricks, the prescribed roof anchor systems perform poorly under the expected South African strong wind climate. The results indicated that the roof anchors will pull out at peak basic wind speeds of between 27 m/s and 32 m/s, and cracks will develop in the masonry prior to anchor pull-out. This study suggests that further research is required to develop adequate roof anchoring methods for LIHs with light-weight roofs, supported on solid brick walls, and that the relevant codes should be amended accordingly. Furthermore, the results showed that the prescribed roof anchor systems for LIHs constructed from hollow blocks performed well and were able to withstand the expected wind loads under the South African strong wind climate.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44180183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-31DOI: 10.17159/2309-8775/2021/v63n4a6
L. De Beer, C. Venter
Many governments in the global south are grappling with challenges of improving the quality of informal transport, and an inability to pay for service improvements. This paper asks the question whether efficiency benefits might be gained through strategic implementation of once-off infrastructure interventions providing priority to informal vehicles at intersections. We note that informal drivers already indicate this demand through (illegal) driving behaviour in traffic. We use a drone to observe indicative behaviours among minibus-taxi drivers in South Africa. We identify interventions that would formalise this behaviour: a single lane pre-signal strategy, queue-jumping lane, and dedicated public transport lane. The objective of the paper is to quantify the potential economic impacts of such treatments on minibus-taxi operators, passengers and other road users. The findings indicate that substantial savings could be realised in terms of travel time, user cost, and operating cost to taxi passengers and drivers without additional costs being incurred by other road users. The single-lane pre-signal strategy, the queue-jumping lane and the dedicated taxi lane saw a decrease in total hourly cost of 12%, 14% and 30% respectively, including construction cost, user cost, and agency cost, indicating a net social benefit. If part of these savings were passed on to passengers, priority infrastructure could serve as an implicit subsidy to public transport users.
{"title":"Priority infrastructure for minibus-taxis: An analytical model of potential benefits and impacts","authors":"L. De Beer, C. Venter","doi":"10.17159/2309-8775/2021/v63n4a6","DOIUrl":"https://doi.org/10.17159/2309-8775/2021/v63n4a6","url":null,"abstract":"Many governments in the global south are grappling with challenges of improving the quality of informal transport, and an inability to pay for service improvements. This paper asks the question whether efficiency benefits might be gained through strategic implementation of once-off infrastructure interventions providing priority to informal vehicles at intersections. We note that informal drivers already indicate this demand through (illegal) driving behaviour in traffic. We use a drone to observe indicative behaviours among minibus-taxi drivers in South Africa. We identify interventions that would formalise this behaviour: a single lane pre-signal strategy, queue-jumping lane, and dedicated public transport lane. The objective of the paper is to quantify the potential economic impacts of such treatments on minibus-taxi operators, passengers and other road users. The findings indicate that substantial savings could be realised in terms of travel time, user cost, and operating cost to taxi passengers and drivers without additional costs being incurred by other road users. The single-lane pre-signal strategy, the queue-jumping lane and the dedicated taxi lane saw a decrease in total hourly cost of 12%, 14% and 30% respectively, including construction cost, user cost, and agency cost, indicating a net social benefit. If part of these savings were passed on to passengers, priority infrastructure could serve as an implicit subsidy to public transport users.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44072132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-31DOI: 10.17159/2309-8775/2021/v63n4a4
S. van der Westhuyzen, J. Wium
High-rise timber buildings have experienced a resurgence internationally during the past two decades. This paper presents an investigation into the financial feasibility of a multi-storey mass timber building for South Africa through a development cost comparison. Two 8-storey commercial buildings - a mass timber frame and a reinforced concrete frame - were first designed by independent engineering consultants. A focus group workshop, conducted with industry professionals, assisted with the development of construction schedules. Subsequently, a financial model was developed to determine the overall development cost and financial feasibility of each option. Finally, a sensitivity analysis was conducted to investigate the effect ol certain variables on the overall profitability of the mass timber frame development. The focus group workshop identified that the construction of the reinforced concrete frame building and mass timber frame building will take 42 weeks and 21 weeks, respectively. The total capital investment required for the mass timber frame development was found to be 10% more than that of the reinforced concrete frame development (R115 691 000 versus R 105 118 000). A five-year internal rate of return (IRR) of 20.9% and 25.7% was calculated for the mass timber and reinforced concrete frame developments, respectively. A significant finding of the sensitivity analysis was that the mass timber frame building proved to generate a higher five-year IRR than that of the reinforced concrete frame once the mass timber building achieved a rental premium of 7.8% or more. The sensitivity analysis further showed that the importation of the mass timber elements remains an expensive option, with a 16.4% five-year IRR for the imported mass timber frame (at a R17:€1 exchange rate).
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