Issue 1, 1990 Civil Engineer in South Africa - Volume 32,
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Arbeidsproduktiwiteit in padkonstruksie in Suid-Afrika : 1977 - 1986 : technical paper
Civil Engineer in South Africa 32, pp 11 –22 (1990)
Die produktiwiteit van aanwending van hulpbronne in siviele ingenieurskonstruksie vir die oprigting van nuttige infrastruktuur is deurslaggewend vir ekonomiese vooruitgang omdat die konstruksiesektor &apos;n groot aandeel in die land se ekonomiese aktiwiteit het. Omdat produktiwiteit gemeet moet word voordat dit verbeter kan word, word &apos;n sewevlak-hierargiese indeling van konstruksiebedrywighede voorgestel, en op elkeen van hierdie vlakke kan en moet produktiwiteit gemeet, gemonitor en verbeter word.
Vir Vlak 5 in die hierargie, nl &apos;Konstruksiesektor&apos;, word &apos;n omvattende indeks vir arbeiderproduktiwiteit in konstruksie afgelei. Dit word getoon dat die indeks se waarde vir elke jaar bereken kan word indien die verandering van jaar tot jaar (vanaf die basisjaar) van drie entiteite bekend is, nl die aantal arbeiders betrokke by die konstruksie, die totale omset van die konstruksiesektor en die geweegde gemiddeldes van tendertariewe in daardie sektor.
Daarna word &apos;n indringende ontleding van alle padkontrakte in Suid-Afrika in die tien jaar 1977-1986 gedoen en daar word aangetoon, beide in tabelvorm en grafies, dat, vir padkonstruksie, arbeiderproduktiwiteit in die eerste gedeelte van die tydperk skerp gedaal het en oor die laaste gedeelte weer skerp gestyg het - noodgedwonge weens die resessionere toestande en dus moordende mededinging om beskikbare werk wat oor daardie tydperk gegeld het.
Daar word aan die hand gedoen dat die metodologie wat hier ontwikkel is, uitgebrei en benut word as bestuurshulpmiddel vir die optimale skedulering van infrastruktuur-ontwikkeling.
Productivity in the use of resources required for civil engineering construction to erect necessary infrastructure is vital for economic progress, because the construction sector is an important component of economic activity in the country. Because productivity has to be measured before it can be improved, a seven-tier hierarchy of construction activities is proposed. Productivity can and should be measured, monitored and improved on each of the seven levels.
For Level 5, &apos;construction sector&apos;, a comprehensive index of labour productivity is developed. It is shown that the index can be calculated for any year if the changes from one year to the next in three entities are known, viz the quantity of labour in construction, the gross turnover of the sector and the weighted mean of all tender rates in that sector.
An in-depth analysis of all road contracts in South Africa for the period 1977-1986 is used as a basis to show, in both tabular and graphical format, that labour productivity in road construction decreased markedly during the first half of this period and thereafter increased sharply owing to the recessionary conditions and the resulting competition for available work.
It is proposed that the methodology developed here be extended and applied as a management tool for the optimal scheduling of infrastructural development.
Appraisal of deflection and cracking models for partially prestressed members : technical paper
Civil Engineer in South Africa 32, pp 23 –33 (1990)
This paper analyses experimental work on partially prestressed members previously reported in the literature, in the light of various existing design models for deflection and cracking. Using the available data in a parametric study, the most suitable design approaches are identified. In some instances improved formulations are derived. In addition, recommendations are made for further experimental work that is required to confirm the long-term deflection and cracking behaviour of partially prestressed members.