Browsing by Author "Viljoen, C."

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    A comparison of technical and practical aspects of Eurocode 3-1-1 and SANS 10162-1 hot-rolled steelwork design codes
    (South African Institution of Civil Engineering, 2016) Walls, R. S.; Viljoen, C.
    In South Africa engineers are starting to use the Eurocode guidelines for steelwork design, and it is important to understand the implications and differences in results that are obtained when applying the different codes. This paper presents a comparison between the Eurocode 1993-1-1:2005 and SANS 10162-1:2005 hot-rolled steelwork design codes. Numerical comparisons of predicted member design strengths for the important modes of failure and the complexity of calculations are presented, along with considerations regarding the parameters used in design. The following are explicitly shown for both codes: (a) differences in the classification of commonly used H, I, PFC and equal L sections, (b) differences in tension resistance calculations, (c) comparisons of all axial buckling curves, (d) calculations for a selection of members in flexural buckling which have different classifications, and (e) a summary of the shear resistances of commonly used H and I sections. It is shown that, on average, Eurocode 3 predicts higher member design strengths than the SANS 10162 code for most failure modes, primarily because of material partial safety factors closer to unity, less conservative buckling curves and the consideration of plastic resistance of sections. These EC3 design capacities can be higher by up to 11% for tension, 35% in compression, 31% in bending and 51% in shear, although there are cases where strengths of up to 33% lower were calculated, such as for an IPEAA-200 in shear. Results are influenced by design geometric tolerances, which are based on section classifications. The Eurocode's equations and design methodologies are more complex and computationally demanding. Since South Africa has started moving in the direction of adapting or adopting Eurocodes with the SANS 10160 Loading Code (from EN 1) and SANS 10100 Structural Concrete Code (from EN 2), it should be considered whether or not the steelwork code should be adopted or adapted in a similar fashion in the future.
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    Reliability assessment of the South African wind load design formulation
    (South African Institution of Civil Engineering, 2018-09) Botha, J.; Retief, J. V.; Viljoen, C.
    ENGLISH ABSTRACT: The representation of the strong wind climate and the reliability calibration of wind loading are the main components of the provisions for local conditions in the South African wind load standard. The reliability implications of new probability models for wind load and an updated map of the characteristic wind speed are assessed in this paper. Wind load probability distributions are based on a combination of new models for free-field wind pressure, pressure coefficients and terrain factors with existing information. The results from both assessments show that the wind load partial factor of 1.3 does not result in adequate reliability performance for typical design situations. A partial factor of 1.6 is recommended. Where an increased partial factor for wind loading will result in a corresponding increase in the design wind load, the introduction of an updated map of the characteristic wind speed for South Africa is shown to result in an overall reduction of wind load. Regional analysis, however, indicates that there are regions in the Western and Eastern Cape that will have increased design wind loads. Combined with an updated partial factor of 1.6, the aggregate increase in design wind loads across South Africa is shown to be 11%.