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A comparison of structural optimization techniques with extension towards multi-objective problems

dc.contributor.advisorVan der Klashorst, Etienneen_ZA
dc.contributor.advisorVan Rooyen, G. C.en_ZA
dc.contributor.authorMuller, Theodorus Ernsten_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.en_ZA
dc.date.accessioned2017-11-13T08:10:22Z
dc.date.accessioned2017-12-11T10:45:45Z
dc.date.available2017-11-13T08:10:22Z
dc.date.available2017-12-11T10:45:45Z
dc.date.issued2017-12
dc.identifier.urihttp://hdl.handle.net/10019.1/102719
dc.descriptionThesis (MEng)--Stellenbosch University, 2017.en_ZA
dc.description.abstractENGLISH 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.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Strukturele optimering vorm 'n belangrike deel van die moderne struktuurontwerp proses om ten einde meer ekonomiese strukture te verkry. Strukture word tipies geoptimeer met die doel om die betrokke struktuur se gewig of verplasing te minimeer. Alhoewel metodes ontwikkel is vir die oorweging van meer as een doel, word normaalweg slegs een oorweeg. Ten opsigte van vakwerk en raam strukture is daar drie aspekte wat oorweeg kan word tydens die optimeringsproses, naamlik elementgrootte, vorm en topologie. Hierdie aspekte verwys respektiewelik na die grootte van elemente, die interne element konfigurasie en die posisionering van knooppunte. Tydens die optimeringsproses kan hierdie aspekte individueel, gelyktydig of agtereenvolgend oorweeg word, alhoewel meestal slegs die element groottes oorweeg word weens die eenvoudigheid daarvan. 'n Doelwit van hierdie studie is om die verbetering in die vakwerk struktuur wanneer 'n meer komplekse optimeringstegniek toegepas word te kwantifiseer, soos byvoorbeeld om al drie aspekte gelyktydig in ag te neem. Verder het hierdie studie ook 'n doelwit om te bepaal of 'n noemenswaardige gewigsbesparing gemaak kan word indien die voorgeskrewe verplasingslimiet van 'n raamstruktuur, wat se verplasing as nie-krities beskou kan word soos byvoorbeeld 'n landelike pakhuis, aangepas word. Hierdie doelwitte word behaal deur beide algehele en strukturele optimering na te vors as ook beskikbare optimeringsalgoritmes. Sagteware is ontwikkel om oplossings vir beide enkel en veeldoelige optimeringsprobleme te vind. Hierdie sagteware word gebruik om verskeie vakwerk probleme vanuit die literatuur te optimeer deur verkillende kombinasies van die voorafgenoemde strukturele aspekte te oorweeg. Die sagteware word ook gebruik om 'n seleksie raamstrukture te optimeer deur beide gewig en verplasing op 'n veeldoelige wyse te minimeer. Dit word gevind dat 'n 22% meer ekonomiese oplossing verkry kan word deur al drie die aspekte gelyktydig te beskou teenoor slegs die element groottes. Vanaf die geoptimeerde raamstrukture word dit gevind dat die meerderheid gewig alreeds bespaar kan word voordat die limiet bereik is. Daarom is 'n aanpassing van die limiet nie nodig nie.af_ZA
dc.format.extent194 pages : illustrationsen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.subjectTruss structuresen_ZA
dc.subjectUCTDen_ZA
dc.subjectStructural optimizationen_ZA
dc.subjectGenetic algorithmsen_ZA
dc.subjectCombinatorial optimizationen_ZA
dc.subjectStructural framesen_ZA
dc.titleA comparison of structural optimization techniques with extension towards multi-objective problemsen_ZA
dc.typeThesisen_ZA
dc.rights.holderStellenbosch Universityen_ZA


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