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Mass and stiffness distributions in optimized ungrouped unbraced frames
Abstract This paper investigates the distribution of mass and stiffness in multi-storey, ungrouped, unbraced, optimized frames. Ungrouped structures are impractical to design and construct. However, optimized, ungrouped structures suggest how structural systems can be improved, and the loads can be carried more efficiently. The Virtual Work Optimization (VWO) method is used to minimize the weight of the structures considered. A 60-storey structure found in the literature is optimized to compare the distribution of mass and stiffness in grouped and ungrouped configurations. A parametric study of frames subjected to lateral loads, ranging in height from 5 to 30 stories, is carried out. Structures are designed to satisfy both strength and deflection criteria. Three different section databases are used for each case study to investigate whether the nature of discrete sections influences results. When ungrouped frames subject to lateral loads are optimized the total stiffness and mass per floor decrease approximately linearly with decreasing height, followed in some cases by a constant region of mass and stiffness, and a decrease in the foundation region. Distinct patterns emerge where members are stiffened on diagonal paths across the width of the structure. The distribution of mass in the frames suggests truss or megabrace behaviour.
Mass and stiffness distributions in optimized ungrouped unbraced frames
Abstract This paper investigates the distribution of mass and stiffness in multi-storey, ungrouped, unbraced, optimized frames. Ungrouped structures are impractical to design and construct. However, optimized, ungrouped structures suggest how structural systems can be improved, and the loads can be carried more efficiently. The Virtual Work Optimization (VWO) method is used to minimize the weight of the structures considered. A 60-storey structure found in the literature is optimized to compare the distribution of mass and stiffness in grouped and ungrouped configurations. A parametric study of frames subjected to lateral loads, ranging in height from 5 to 30 stories, is carried out. Structures are designed to satisfy both strength and deflection criteria. Three different section databases are used for each case study to investigate whether the nature of discrete sections influences results. When ungrouped frames subject to lateral loads are optimized the total stiffness and mass per floor decrease approximately linearly with decreasing height, followed in some cases by a constant region of mass and stiffness, and a decrease in the foundation region. Distinct patterns emerge where members are stiffened on diagonal paths across the width of the structure. The distribution of mass in the frames suggests truss or megabrace behaviour.
Mass and stiffness distributions in optimized ungrouped unbraced frames
Walls, Richard (author) / Elvin, Alex (author)
International Journal of Steel Structures ; 10 ; 233-242
2010-09-01
10 pages
Article (Journal)
Electronic Resource
English
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