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- Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese
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- Volume 45, Issue 1, 2003
Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese - Volume 45, Issue 1, 2003
Volumes & issues
Volume 45, Issue 1, 2003
The achievement of uniformity of straining during concrete cube testing in South Africa : technical paperSource: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45, pp 2 –8 (2003)More Less
The need for checking on the extent of non-uniform straining of concrete cubes by testing machines in South Africa is reviewed. The magnitude of the effect of non-uniform straining on apparent cube strength is reported. The existing 'strain column' method for preventing non-uniform straining by testing machines is compared to a proposed new procedure in which the amount of strain non-uniformity that occurs in the course of normal cube testing is measured, then the effect it has had on the cube's strength is determined.
The impact of location choice factors on retail suburbanisation based on a stated preference model developed for Cape Town : technical paperAuthor N.J.W. Van ZylSource: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45, pp 9 –18 (2003)More Less
Suburbanisation, which involves the general shift in business activities from the central business district (CBD) of cities to the suburban areas, has lead to multi-dimensional and complex problems. Urban planners have proposed various urban densification strategies, such as corridor development, to address the structural problems of South African cities. To define the most effective policies to attract development to priority development corridors and nodes, metropolitan authorities need to understand the locational choice behaviour of the various urban activities and need to quantify the demand elasticities of the main factors driving locational choice. <br>The paper summarises research conducted for the purposes of the author's PhD thesis at the University of Stellenbosch. The main purpose of the research was to determine the locational choice behaviour of retail businesses in strategic spatial terms, in order to assist metropolitan authorities and planners to formulate effective urban densification strategies and to manage suburbanisation. The paper discusses the market research conducted among a sample of retail managers in Cape Town and the quantification of the relative importance and elasticities of locational choice factors derived from stated preference (SP) models that were calibrated on the survey data. The testing of decentralisation strategies with a retail location spreadsheet model based on the SP model results are discussed as well as policies to promote urban densification and to manage suburbanisation
Source: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45, pp 19 –24 (2003)More Less
Fly ash or pulverised fuel ash is a by-product of the combustion of pulverised coal in thermal power plants. The recognition that fly ash frequently exhibits pozzolanic properties has led to its use as a constituent of concrete. In South Africa the carbon content (as measured by loss on ignition, LOI) and the particle size of classified ash is limited to 5 % LOI and less than 12, 5 % larger than 45 (m respectively. Furthermore, the maximum percentage of cement that can be replaced using ash is normally limited to 30 %. A literature review was undertaken to establish the relevance of these limitations based on international research findings. In this article results published by other researchers were reworked and are presented in graphical form to emphasise the effect of carbon content and particle size. Research results indicate that ash with high carbon content reduces the workability of mixtures thus increasing the water demand thereby reducing the strength of the concrete. No proof could be found that the particle size of ash has an effect on the strength of the concrete. The use of large percentages of ash replacement does result in reduced early strength but for specific applications there could be benefits in replacing high percentages of cement with ash. Research should be conducted to establish whether sources of ash previously deemed unfit for use in concrete could be used in future.
Effect of ductility on load-carrying capacity of steel fibre reinforced concrete ground slabs : technical paperSource: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45, pp 25 –30 (2003)More Less
Steel fibre reinforced concrete (SFRC) is increasingly being used for ground slab applications. The addition of steel fibres to concrete imparts significant post-cracking ductility (toughness). This ductility is used to determine a post-cracking strength, which when combined with the pre-cracking strength forms the so-called 'design strength' for SFRC ground slabs. Consequently, the SFRC slab thickness can be reduced in comparison with plain concrete (brittle) slabs. The aim of this paper was to assess the effect of ductility on the load-carrying capacity of SFRC slabs and subsequently compare the deformation behaviour of the SFRC slab to an equivalent plain concrete slab. Based on the post-cracking strength specified by the steel fibre manufacturer, a SFRC ground slab was designed to collapse at the same load as the failure load of a plain concrete slab. The two slabs were then cast, cured for 28 days and afterwards loaded at their centre points till failure. Although the SFRC slab was designed to be 16, 6 % thinner, the measured failure load and deflection were found to be approximately equal for the two slabs. These test results indicate that the load-carrying capacity of concrete ground slabs can be increased by inclusion of nominal steel fibre contents.
Joint type and the stability behaviour of steel frame beams In Journal of the South African Institution of Civil Engineering, 44(4) 2002, pp.2-7 : discussionSource: Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese 45 (2003)More Less
Extracted from text ... Discussion 'Joint type and the stability behaviour of steel frame beams' by A Masarira in Journal 44(4), 2002 Comments received from Dirk P du Plessis MSAICE The author is to be commended for his very interesting and thought-provoking paper. The paper centres on the DIN equation for lateral-torsional buckling of steel beams and its use of the ? coefficients for bending and warping. Using a finite element program the author was able to determine relative warping stiffnesses for ten joint types beam-to-column connections). He then determined the critical loads for several rectangular portal frames keeping the ..