Session Dates
24 Aug 2012 - 25 Aug 2012
Abstract
The objective of this paper is to introduce appropriate constraints in the shape optimization of a cold- formed steel column such that the resulting optimized shapes retain the strength benefits of unconstrained optimal solutions combined with practical manufacturing and constructional needs. Unconstrained shape optimization of cold-formed steel columns, where the cross-section that maximizes axial capacity is found, has previously been performed. Here, practical manufacturing and construction constraints are introduced into the optimization algorithm. Members with three lengths: 2 ft, 4 ft, and 16 ft, are considered. Optimized sections from multiple runs show uniformity and bear a close resemblance to unconstrained results. A point-symmetric ‘S’-shaped section has maximum capacity for long columns and a singly-symmetric ‘∑’-shaped section with complex lips performs best for shorter columns. The observed strength loss from the unconstrained optimal design, to the constrained optimal design, is within ten percent. A simultaneous perturbation stochastic approximation algorithm, with the idea of injecting randomness in the gradient approximation to save computational cost, is adopted as the local optimizer. A systematic survey on a family of lipped channel cross-sections using the same amount of material was carried out. Comparison reveals that the optimized shapes have much larger capacities and exhibit the potential to seed a new generation of commercial products.
Department(s)
Civil, Architectural and Environmental Engineering
Research Center/Lab(s)
Wei-Wen Yu Center for Cold-Formed Steel Structures
Meeting Name
21st International Specialty Conference on Cold-Formed Steel Structures
Publisher
Missouri University of Science and Technology
Document Version
Final Version
Rights
© 2012 Missouri University of Science and Technology, All rights reserved.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Leng, J.; Li, Z.; Guest, J. K.; and Schafer, B. W., "Constrained Shape Optimization of Cold-formed Steel Columns" (2012). CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018). 2.
https://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session2/2
Constrained Shape Optimization of Cold-formed Steel Columns
The objective of this paper is to introduce appropriate constraints in the shape optimization of a cold- formed steel column such that the resulting optimized shapes retain the strength benefits of unconstrained optimal solutions combined with practical manufacturing and constructional needs. Unconstrained shape optimization of cold-formed steel columns, where the cross-section that maximizes axial capacity is found, has previously been performed. Here, practical manufacturing and construction constraints are introduced into the optimization algorithm. Members with three lengths: 2 ft, 4 ft, and 16 ft, are considered. Optimized sections from multiple runs show uniformity and bear a close resemblance to unconstrained results. A point-symmetric ‘S’-shaped section has maximum capacity for long columns and a singly-symmetric ‘∑’-shaped section with complex lips performs best for shorter columns. The observed strength loss from the unconstrained optimal design, to the constrained optimal design, is within ten percent. A simultaneous perturbation stochastic approximation algorithm, with the idea of injecting randomness in the gradient approximation to save computational cost, is adopted as the local optimizer. A systematic survey on a family of lipped channel cross-sections using the same amount of material was carried out. Comparison reveals that the optimized shapes have much larger capacities and exhibit the potential to seed a new generation of commercial products.
