Browsing by Author "Wium, Jan"

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    Assessment of the behaviour factor for the seismic design of reinforced concrete structural walls according to SANS 10160 : part 4
    (South African Institution of Civil Engineering, 2012-04) Le Roux, Rudolf; Wium, Jan
    Reinforced concrete structures, designed according to proper capacity design guidelines, can deform inelastically without loss of strength. Therefore, such structures need not be designed for full elastic seismic demand, but could be designed for a reduced demand. In codified design procedures this reduced demand is obtained by dividing the full elastic seismic demand by a code-defined behaviour factor. There is, however, no consensus in the international community regarding the appropriate value to be assigned to the behaviour factor. The purpose of this study is to assess the value of the behaviour factor currently prescribed by SANS 10160-4 (2011) for the design of reinforced concrete structural walls. This is done by comparing displacement demand to displacement capacity for a series of structural walls. The first step in seismic force-based design is the estimation of the fundamental period of the structure. The influence of this first crucial step is investigated in this study by considering two period calculation methods. It was found that, regardless of the period calculation method, the current behaviour factor value prescribed in SANS 10160-4 (2011) is adequate to ensure that inter-storey drift of structural walls would not exceed code-defined drift limits.
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    The management of constructability knowledge in the building industry through lessons learnt programme
    (South African Institution of Civil Engineering, 2014-04) Kuo, Vincent; Wium, Jan
    In the 1980s the term "constructability" evolved in the USA. The proponents of this concept believe that constructability, which embraces both design and management functions, is comprehensive in facilitating construction operations and solving problems on site. Constructability problems are common on the construction site, due to the lack of construction experience in the design team and the absence of tools to assist designers in addressing constructability. Moreover, designs are predominantly done early in the project in the absence of contractor input, and there is yet no explicit means of defining or measuring constructability. This paper aims to address constructability problems in building construction, by understanding the nature of constructability knowledge and investigating how construction experience may be effectively disseminated amongst project participants, particularly through the use of lessons learnt programmes and inter-disciplinary knowledge sharing. It has been found that there is fundamental misalignment between consultants and contractors on the perceptions of criteria for a constructible design, implications of design decisions, and certain traits that may represent optimised vs poor constructability. The discrepancy in communication is the elemental cause of constructability problems and this research has demonstrated how lessons learnt programmes can be an effective tool in attaining better constructability knowledge management and collaboration.
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    Rocking shear wall foundations in regions of moderate seismicity
    (South African Institution of Civil Engineering, 2013-10) Van der Merwe, Johann E.; Wium, Jan
    ENGLISH ABSTRACT: This paper presents a study which investigates the feasibility of a concept to reduce the size of shear wall foundations for earthquake forces in regions of moderate seismicity. The approach is to allow rocking of the shear wall foundation and to include the contribution of a shear wall and reinforced concrete frame to assist as a lateral force-resisting system. A simplified multi degree-of-freedom model with non-linear material properties was used to investigate this lateral-force-resisting system subjected to base accelerations from recorded ground motions. An example building was studied with the shear wall foundation designed to resist 0%, 20%, 40%, 60%, 80% and 100% of the design overturning moment from the seismic event. Non-linear time-history analyses were performed with input from seven scaled ground-motion records. It is shown that the concept warrants more detailed studies and that a significantly reduced shear wall foundation size is possible without failure of the lateral force-resisting system.