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IASS-SLTE Symposium 2014: Shells, Membranes and Spatial Structures: Footprints


IASS Symposium 2014

SESSION: General 9: Computational Tools, Shape Finding and Optimization

An automated robust design methodology for suspended structures

< Table of Contents for General 9: Computational Tools, Shape Finding and Optimization
  • Proceedings Name: IASS-SLTE Symposium 2014: Shells, Membranes and Spatial Structures: Footprints
  • ISSN: (Electronic Version) 2518-6582
  • Session: General 9: Computational Tools, Shape Finding and Optimization
  • Title: An automated robust design methodology for suspended structures
  • Author(s): Edward M. SEGAL, Landolf RHODE-BARBARIGOS, Rajan D. FILOMENO COELHO, Sigrid ADRIAENSSENS
  • Keywords: robust design, suspended structure, dynamic relaxation, multicriteria optimization, polynomial chaos expansion, polyester-rope suspended footbridge
Abstract
Suspended structures such as cable roofs and bridges are lightweight spatial tensile systems. The objective of this paper is to present an automated robust design methodology for suspended structures. Whereas design methods for these systems may focus either on optimality or robustness, the proposed method accounts for static and dynamic behavior while optimizing for multiple criteria and dealing with uncertainties (robustness) simultaneously. Numerical simulations combine dynamic relaxation for the nonlinear structural analysis with a non-dominated sorting genetic algorithm (NSGA-II) for the multicriteria optimization. The formulation used is general and adaptable to allow for handling of multiple objectives and constraints concurrently. To obtain robust designs, the procedure accounts for random uncertainties. Uncertainties are given for the model inputs and translated into outputs with associated uncertainties. Polynomial chaos expansion (PCE) is used to generate reduced-order stochastic structural analysis models in order to get statistical robust measures with reasonable computational time. A case study of a polyester-rope suspended footbridge is used to demonstrate how the methodology accommodates both static and dynamic parameters. Test cases in which Young’s Modulus and prestress are taken as random variables are examined. Two objectives (maximization of the lowest in-plane natural frequency and minimization of rope volume) and two static constraints (maximum stress and maximum slope) are considered simultaneously. Pareto fronts for the deterministic and robust designs are compared and found to be similar for all test cases examined; therefore, for this case study the deterministic solution is also the most robust. The general automated design methodology presented in this paper can be applied to other suspended systems where different constraints, objectives, and uncertainties, may be of interest. Thus, this methodology serves as a powerful computational tool for the design of robust suspended structures.

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