Thesis (MScIng)--University of Stellenbosch, 2007. / Bibliography.

Thesis (MScEng (Civil Engineering)--University of Stellenbosch, 2007. / The introduction of toughened glass into the construction industry has had several significant consequences. For the first time, glass panels can be used without continuous edge supports, and as a result can be used as load-bearing element. An excellent and very common example of the use of glass as structural element is a freestanding glass balustrade. During an undergraduate investigation, a number of impact tests were performed on continuous supported freestanding glass balustrade panels at the University of Stellenbosch [6]. It was observed that none of the balustrade panels complied with the guidelines for impact loading stipulated in the SABS [7] loading standards. The failure to meet the loading requirements highlighted the need to investigate the design of glass balustrades. This thesis describes the investigation undertaken to determine the static- and dynamic loading capacity of freestanding glass balustrades. Following a review of South African and international design standards, the static- and dynamic material properties of toughened glass was established by means of a laboratory test series. The laboratory test series consisted of both a destructive laboratory test series and finite element analysis, the outcome of which determined the static- and dynamic material properties of toughened glass. The series also included the influence of different connection types. A second phase employed the identified material properties of toughened glass to determine the loading capacity of full-scale balustrades. Using finite elements each balustrade set-up was loaded as required by the relevant South African loading standards. The finite element analyses identified which balustrade set-ups could resist the required imposed loads. Finally, a second laboratory test series was undertaken, the aim of which was to verify the finite element results. The successful resistance of the tested balustrade set-ups confirmed the finite element model. Recommendation to the existing design- and loading standards are made based on the results of the thesis.

Low-rise buildings are often subjected to high wind loads during hurricanes that lead to severe damage and cause water intrusion. It is therefore important to estimate accurate wind pressures for design purposes to reduce losses. Wind loads on low-rise buildings can differ significantly depending upon the laboratory in which they were measured. The differences are due in large part to inadequate simulations of the low-frequency content of atmospheric velocity fluctuations in the laboratory and to the small scale of the models used for the measurements. A new partial turbulence simulation methodology was developed for simulating the effect of low-frequency flow fluctuations on low-rise buildings more effectively from the point of view of testing accuracy and repeatability than is currently the case. The methodology was validated by comparing aerodynamic pressure data for building models obtained in the open-jet 12-Fan Wall of Wind (WOW) facility against their counterparts in a boundary-layer wind tunnel. Field measurements of pressures on Texas Tech University building and Silsoe building were also used for validation purposes. The tests in partial simulation are freed of integral length scale constraints, meaning that model length scales in such testing are only limited by blockage considerations. Thus the partial simulation methodology can be used to produce aerodynamic data for low-rise buildings by using large-scale models in wind tunnels and WOW-like facilities. This is a major advantage, because large-scale models allow for accurate modeling of architectural details, testing at higher Reynolds number, using greater spatial resolution of the pressure taps in high pressure zones, and assessing the performance of aerodynamic devices to reduce wind effects. The technique eliminates a major cause of discrepancies among measurements conducted in different laboratories and can help to standardize flow simulations for testing residential homes as well as significantly improving testing accuracy and repeatability. Partial turbulence simulation was used in the WOW to determine the performance of discontinuous perforated parapets in mitigating roof pressures. The comparisons of pressures with and without parapets showed significant reductions in pressure coefficients in the zones with high suctions. This demonstrated the potential of such aerodynamic add-on devices to reduce uplift forces.

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