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

IASS Symposium 2014

SESSION: Computational Methods

Revisiting Harrison’s iterative method for the analysis of inflatable dams

< Table of Contents for Computational Methods
  • Proceedings Name: IASS-SLTE Symposium 2014: Shells, Membranes and Spatial Structures: Footprints
  • ISSN: (Electronic Version) 2518-6582
  • Session: Computational Methods
  • Title: Revisiting Harrison’s iterative method for the analysis of inflatable dams
  • Author(s): Matthew STREETER, Landolf RHODE-BARBARIGOS, Sigrid ADRIAENSSENS
  • Keywords: numerical method, form-finding and analysis, membrane, inflatable structure, dam
Inflatable dams are flexible membrane structures inflated by air and/or water that pose a potential solution to storm surge flooding from the increasing number and intensity of tropical storms hitting the eastern seaboard of the United States of America. Like all membrane structures, inflatable dams are form-found structures. Therefore, the dam’s initial equilibrium shape must be determined by either experimental or numerical form-finding methods. However, contrary to traditional membrane applications, the applied loading due to the air/water on a dam is coupled with its shape as changes in the form of the membrane also induce changes in the loading. In this paper, the numerical method, proposed by Harrison in 1970, for the cross-sectional static analysis of an inflatable dam is revisited. Harrison studied air-inflated and water-inflated dams under different conditions of upstream and downstream water depth and internal pressure. The membrane section is assumed to be composed of a large number of linear tensile elements. An equilibrium profile is achieved through an iterative process by solving local equilibrium at each node until the specified positions of the anchored points are matched (satisfy boundary conditions). The method is found to be computationally advantageous when good initial guess values for the tension and orientation of the first element are provided. However, Harrison’s method in its original version is only adequate for systems with sufficient anchor point separation and cannot support systems combined with a rigid gate element, limiting its application for pneumatically actuated gate systems. In this study, Harrison’s original algorithm is implemented, validated and extended to include single anchor-point systems, an internal pressure update as well as gate-supporting systems. With the extensions proposed in this paper, we extend the scope of the method providing an alternative computational tool for the preliminary analysis of inflatable dams.

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