Browsing by Author "Muller, Theodorus Ernst"
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- ItemA comparison of structural optimization techniques with extension towards multi-objective problems(Stellenbosch : Stellenbosch University, 2017-12) Muller, Theodorus Ernst; Van der Klashorst, Etienne; Van Rooyen, G. C.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: Structural optimization is becoming an integral part of the modern structural design process in the search to yield more economical structures. The optimization of structures is typically performed with the objective to minimize weight or displacement primarily for cost reasons. Normally only one objective is considered, but methods enabling the consideration of multiple objectives have been developed. With respect to truss and frame structures, there are three well-known aspects which can be considered during the optimization process, namely, member sizing, shape and topology. These aspects refer to the size of the structure's members, the internal member configuration and its nodal positioning respectively. During the optimization, these aspects can be considered individually, simultaneously or sequentially, although typically only member size is considered due to its simplicity. This study aims to quantify the weight reduction in the resulting truss structure by applying a more complex optimization approach such as considering the three aspects simultaneously. Furthermore, this study also aims to determine whether or not a meaningful weight reduction can be achieved by adjusting the prescribed deflection limit of a frame structure whose maximum deflection can be regarded as non-critical, for example a rural warehouse. These aims are achieved by researching both general and structural optimization as well as available algorithms for successfully optimizing a structure. Software is developed to find solutions to both single- and multi-objective optimization problems. The software is used to optimize various truss problems found in literature by considering different combinations of the aforementioned structural aspects. The software is also used to optimize a selection of frame structures in a multi-objective It is concluded that a 22% more economical solution can be found by considering the three aspects simultaneously as opposed to considering only member size. From the frame structures considered in this study, it is concluded that the majority of the structure's weight can be reduced before the deflection limit is reached. Therefore, an increase in the displacement limit is not required.