Collapse Simulations of Can-Welded Steel Cylinders with Measured Imperfections under Pure Bending

The objective of this paper is to validate and apply a series of finite-element models for the flexural strength of thin-walled, can-welded steel cylinders, as utilized in the supporting structure of wind turbine towers. An existing set of flexural experiments on 1-m-diameter can-welded steel tubes that included detailed laser scanning of the initial geometry are employed as benchmarks for modeling. Modeling assumptions included element selection, mesh, and aspect ratio; end boundary conditions; loading; material modeling; and detailed consideration of geometric imperfections. Although the initial geometry of the tubes is fully established, interpolation is required due to some features of the specimens (e.g., weld beads) and the scanning method. The developed simulations show good agreement with the benchmark tests. Although the tests can only be conducted to flexure about a single axis, the simulations can be extended to explore the flexural capacity about any imposed axis. This is relevant for the intended application of wind turbine support towers—and through simulation the envelope of expected flexural strength about any axis is developed. Guidance is then provided on which imperfection magnitudes and locations are most well correlated with strength along with discussions for further improvements and future work relevant to simulating thin-walled tubes as applied in wind turbine support towers.