By using a nonlinear computer analysis, a parametric study is developed in order to examine the accuracy of the Moment Magnifier Method of the American Concrete Institute Code (ACI 318-83). The variables used in the parametric study are: axial load intensity, P/Po; column reinforcement ratio, rho; slenderness ratio, klu; shape of column cross section, flexural stiffness ratio, and distribution of axial loads. In the parametric study, 216 cases of single bay fixed-base portal frames are examined. The higher moment for each one of these frames at failure are then compared with the design moment predicted by the Moment Magnifier Method of the American Concrete Institute Code (ACI 318-83). The Moment Magnifier Method proved to be very conservative when the columns are subjected to high level of axial loads and when the slenderness ratio is increased.

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The Department of Water Affairs and Forestry infrastructure has shown a decline in condition from 2006 to 2011, according to the Infrastructure Report Card. With the increase in population, the additional demand placed on the already ageing infrastructure together with inadequate maintenance exacerbates the deterioration of these structures. Much has been done to improve the provision of basic water services to South Africans, however to ensure that basic water services remain intact, maintenance of the existing structures is of paramount importance. The storage of potable water in a hygienic manner is essential to the water provision network, thus focus is placed on water reservoirs (in particular reinforced concrete water reservoirs). It has been identified that there is a lack of appropriate policies, practices, procedures and guidelines related to the maintenance of municipal water reservoirs. The solution that this study proposes is to develop a maintenance prioritization method for reinforced concrete water reservoirs. This method specifically provides the user (i.e facility manager) with a systematic approach to assessing and allocating a condition value to the reservoir, which is used to prioritize maintenance activities. This method follows the approach used by the TRH/TMH manuals and bridge management systems that are implemented throughout South Africa. This method includes, the breakdown of essential reservoir components thus facilitating the development of future asset registers, the deterioration mechanisms that affect these reservoirs along with the appropriate identification methodologies and the percentage contributions of each component to the overall condition of the facility. The research for the prioritization method is conducted by combining literature with feedback from industry professionals. The literature featured investigation of the components of concrete reservoirs and deterioration mechanisms that affect these components. The results of the feedback from the industry professionals indicated that some of the components contribute more to the overall condition of the facility than others. This contribution is based on the importance of the component with regard to the provision of service and safety. Thus, in the case of a concrete reservoir, the walls are more essential to the provision of service and safety than the access components, thus its contribution percentage is higher. The research suggests that if the prioritization method could successfully be implemented, it will provide the users additional information that can be used to prioritise maintenance activities at both component and network level. Further, it may allow for the development of a comprehensive asset register of concrete reservoirs and may also aid in the financial planning related to the maintenance of these structures. / AFRIKAANSE OPSOMMING: Die Departement van Waterwese en Bosbou se infrastruktuur het n afname in kondisie gradering getoon van 2006 tot 2011 volgens die Infrastruktuur Verslag Kaart. Die toename in die bevolking veroorsaak bykomende druk op die reeds verouderende infrastruktuur wat tesame met swak instandhouding die agteruitgang van hierdie strukture vererger. Baie is gedoen om die voorsiening van basiese waterdienste aan Suid-Afrikaners te verbeter, maar dit is uiters noodsaaklik dat bestaande strukture in stand gehou word om te verseker dat basiese waterdienste beskikbaar bly. Die berging van drinkwater op ’n higiëniese wyse is noodsaaklik vir die watervoorsieningsnetwerk met die gevolg dat daar op waterreservoirs, spesifiek gewapende beton waterreservoirs, gefokus word. Daar is vasgestel dat daar nie toepaslike praktyke, prosedures en riglyne met betrekking tot die instandhouding van van munisipale waterreservoirs bestaan nie. Die oplossing wat deur hierdie studie voorgestel word, is om ’n onderhoud prioritisering metode vir gewapende beton waterreservoirs te ontwikkel. Hierdie metode bied spesifiek aan die gebruiker (reservoir bestuurder) ’n sistematiese benadering om ’n toestandwaarde ten opsigte van die reservoir te bepaal en toe te wys, wat gebruik word om instandhoudingsaktiwiteite te prioritiseer. Hierdie metode volg die benadering van die TRH/TMH en brug bestuur sisteme, wat geimplimenteer word reg deur Suid Afrika. Hierdie metode sluit in die klassifiseering van hoof komponente van ’n gewapende beton reservoir wat die ontwikkeling van toekomstige bateregisters, die degenerasiemeganismes wat hierdie reservoirs beïnvloed tesame met die gepaste identifiseringsmeganismes en die bydrae volgens persentasie van elke komponent tot die algehele toestand van die fasiliteit, fasiliteer. Die navorsing ten opsigte van die prioritiserings metode is uitgevoer deur literatuur met terugvoer van bedryfskundiges te kombineer. Die literatuur wat geraadpleeg is handel oor die ondersoek na die komponente van gewapende beton reservoirs en degenerasiemeganismes wat hierdie komponente beïnvloed. Die studie dui aan dat, aan die hand van die bedryfskundiges se terugvoer, sommige komponente meer as ander tot die algehele toestand van die fasiliteit bydra. Hierdie bydrae is gebaseer op die belangrikheid van die komponent in terme van die voorsiening van dien ek veiligheid. Dus, is die geval van n beton reservoir, is die mure meer van beland as die toegans komponente in terme van voorsiening van diens en veiligheid. Die navorsing gee te kenne dat indien die prioritiserings metode suksesvol geïmplementeer kan word, dit die gebruiker bykomende inligting kan gee wat gebruik kan word om die instandhoudingsaktiviteite te prioritiseer op beide netwerk en komponente vlak. Verder, mag daar ’n omvattende bateregister van gewapende beton reservoirs ontwikkel kan word wat dus sal help met die finansiële beplanning rondom die instandhouding van hierdie strukture.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Civil Engineering / Master / Master of Philosophy

published_or_final_version / abstract / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Civil Engineering / Master / Master of Philosophy

published_or_final_version / abstract / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Civil Engineering / Master / Master of Philosophy

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Currently, in Texas, there is a need for different repairs on pavements and bridge decks; rapid repair materials designed for these repairs are available but the service life and durability of these products are often inadequate. Thus, the goal for the Texas Department of Transportation (TxDOT) is to implement repairs with an extended service life in a timely manner, in order to cause minimal disruption. Research performed under TxDOT Project 6723 (Development of Rapid, Cement-based Repair Materials for Transportation Structures) evaluated a wide range of rapid repair materials, including calcium aluminate cement (CAC), calcium sulfoaluminate cement (CSA), fly ash alkali activated blends, and ordinary portland cement. Some of the properties which contribute to a long-term service life are: mechanical properties, early-age volume change, and the heat evolution; often, the early-age development of these repair materials can cause later durability issues. These properties were examined through a variety of experiments and test in the laboratory, as well as, in the field. / text