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


IASS Symposium 2014

SESSION: Structural Morphology 3: Morphology and Transformables

Optimizing a trussed frame subjected to wind using Rhino, Grasshopper, Karamba and Galapagos

< Table of Contents for Structural Morphology 3: Morphology and Transformables
  • Proceedings Name: IASS-SLTE Symposium 2014: Shells, Membranes and Spatial Structures: Footprints
  • ISSN: (Electronic Version) 2518-6582
  • Session: Structural Morphology 3: Morphology and Transformables
  • Title: Optimizing a trussed frame subjected to wind using Rhino, Grasshopper, Karamba and Galapagos
  • Author(s): Evan J. GERBO, Edmond P. SALIKLIS
  • Keywords: optimization, genetic algorithm, structural analysis, form finding
Abstract
This paper presents an approach to optimization of efficiency in a building trussed frame. The process of optimization was the repeated reconstruction of models in an attempt to create a structure that has minimal weight in its columns and in its diagonal braces, coupled with minimal lateral deflection at the roof level, for a given applied lateral wind load on one side of the trussed frame. The optimization was handled entirely in the virtual environment provided by Rhino, Grasshopper, Karamba and the evolutionary algorithm Galapagos. This parametric model created a loop that automatically redesigned columns, and braces as well as the width of the bay at each story level. This process is completed with an Evolutionary Solver that uses genetic fitness to eliminate unwanted characteristics (here larger weight and larger top deflection) and to select genes (here member sizes and bay width per story) that evolved towards genetic success (here minimum weight as well as minimum lateral roof movement). A unique feature of this optimization is the efficient reduction of variables that were genetically modified. This reduction greatly enhanced the speed of the process and made the optimization so efficient that 40 or 50 generations of modifications can occur in a few minutes on a laptop. Several braced frames were used in the parametric model, these were subjected to ASCE 7 Wind Loads and the results of the structural analysis performed by Karamba on the optimized structures were compared to results from a commercially available traditional structural analysis package. The comparisons were excellent, giving us further confidence into delving deeper into the physics engine of Karamba, apart from traditional finite element programs.

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