The efficiency of a structure defines the relationship between its performance and cost. Studies of structural efficiency will inevitably lead to improved structural performance and/or reduced material consumption. There are various routes to achieve more efficient structures, and the use of mechanics/structural concepts provides one important option. These concepts are valid for a broad range of structures, easy to understand and play a decisive role in a conceptual or scheme design stage which is the most influential stage for determining structural efficiency. However, there are few systematic studies of structural efficiency from the perspective of mechanics concepts. This provides the rationale for exploring mechanics concepts to improve the efficiency of structures. Three effective concepts are used as a basis for this study, that more direct force paths, smaller internal forces and more uniform force/stress distribution lead to a stiffer or more efficient structure. These concepts can only be realized in particular types of structure through taking appropriate measures. Therefore, this thesis aims to improve structural efficiency by making good use of some existing measures, developing new measures, providing a theoretical basis to some effective measures and abstracting general principles from some available measures based on the three concepts. The following items are investigated in this thesis: 1. For two existing approaches searching for efficient structural forms, the intuitive use and mathematical realisation (evolutionary structural optimization (ESO)) of structural concepts, their complementary characters are first identified which inspire a comparative study of the solutions. Through this study, the efficient profiles of a mid-span loaded thick beam and effective bracing arrangements for laterally braced frames are revealed; governing concepts affecting structural efficiency in particular conditions are discussed; and some design measures for designing efficient structural forms in the two groups of cases are presented. 2. As new measures, design criteria for effective bracing systems in simple and tall frames are developed, based on the concepts of direct force paths and small internal forces. The criteria are shown to be effective as a two-stage design procedure, with the arrangement of braced panels followed by that of bracing member orientation. 3. A theoretical study of an existing beam stiffening measure using external tendons is conducted, focusing on the stiffness and natural frequencies of a stiffened beam. It provides quantitative estimation of the stiffening effect and theoretical evaluation of the governing factors and optimal profile for designing the profiled tendons. 4. The effective measures leading to the high efficiency of the Raleigh Arena are identified and studied. The efficiency of the Arena is evaluated quantitatively using numerical methods. The concept of smaller internal forces can be abstracted from one physical measure used in the Arena.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:553441 |
| Date | January 2012 |
| Creators | Yu, Xiaoye |
| Contributors | Ji, Tianjian |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/improving-the-efficiency-of-structures-using-mechanics-concepts(01e6d6f8-c88c-4ff3-8db6-4dde36415c72).html |
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