Advanced Numerical Modeling of Cracked Tubular Joints: BEM and FEM Comparison
Publication: Journal of Bridge Engineering
Volume 17, Issue 3
Abstract
A critical aspect in the design of tubular bridges is the fatigue performance of the structural joints. The estimation of a fatigue crack life using the linear elastic fracture mechanics (LEFM) theory involves the calculation of stress intensity factors (SIF) at a number of discrete crack depths. The most direct way is to carry out modeling by either the finite-element method (FEM) or the boundary-element method (BEM). For tubular joints commonly found in tubular bridges and off-shore structures, due to the complicated geometry resulting from the tube intersections and welding, the construction of the numerical model often becomes a complex process. This paper presents two different model construction techniques that have been developed independently at the Swiss Federal Institute of Technology (EPFL) and the Nanyang Technological University (NTU), Singapore, that are based in the BEM and the FEM, respectively. The SIF values obtained by these two methods are compared. It is found that as long as consistent geometric models are employed, compatible SIF values can be obtained by both approaches. The best and the most consistent values are obtained for the deepest point along the crack front and should be used for fatigue-life computations.
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Acknowledgments
The first author would like to acknowledge the funding assistance provided by the Swiss National Science Foundation (SNSF) for his Ph.D. study and the School of Civil and Environmental Engineering, NTU for his academic visit to NTU, Singapore, in February 2009.
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Information
Published In
Journal of Bridge Engineering
Volume 17 • Issue 3 • May 2012
Pages: 432 - 442
Copyright
© 2012. American Society of Civil Engineers.
History
Received: Oct 25, 2010
Accepted: May 24, 2011
Published online: May 26, 2011
Published in print: May 1, 2012
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