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From:
Abdullah Mahmoud (1), Shahabeddin Torabian (2), Angelina Jay (3), Andrew Myers (3), Eric Smith (4), Benjamin W. Schafer (1)
(1) Department of Civil Engineering, Johns Hopkins University,
(2) Department of Civil Engineering, Johns Hopkins University and School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran,
(3) Dept. of Civil and Env. Eng., Northeastern University,
(4) Keystone Tower Systems
“Modeling protocols for elastic buckling and collapse analysis of spirally welded circular hollow thin-walled sections”, Proceedings of the Annual Stability Conference Structural Stability Research Council (SSRC) Nashville, Tennessee, March 24-27, 2015
ABSTRACT: The elastic buckling and ultimate capacity of thin-walled steel circular hollow sections manufactured with spiral welding and subjected to axial force or pure bending are studied numerically in ABAQUS and experimentally validated to provide a numerical modeling protocol. This effort, focused on shell finite element analysis and the development of validated modeling protocols, is a part of a larger effort to definitively understand the limit-states and provide design standards for spirally welded steel wind turbine towers. The modeling protocol incorporates fundamental modeling parameters including element type, mesh aspect ratio, mesh style including structured mesh versus spiral mesh along the spiral welds, mesh size along the length, mesh size on the circular cross-section, material modeling, geometrical imperfections, and weld imperfections. The geometrical dimensions in the parametric analyses were selected in accordance with reasonable archetype dimensions and practical plate thicknesses and cross- sectional diameters applicable to wind turbine towers. An eigen-buckling convergence study including both buckling shapes and capacities was performed under pure bending and compressive axial force to find a base-line modeling protocol. To validate the base-line modeling protocol, a spirally welded tube specimen recently tested at Northeastern University was simulated via geometric and material nonlinear shell finite element analysis. The validated protocol will be applied to a larger parametric collapse analyses to generalize the experimental results and to develop reliability based design methods for spirally welded wind turbine towers.
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