Proceedings of the Annual Stability Conference Structural Stability Research Council St. Louis, Missouri, April 2-5, 2019 On the buckling behavior of thin-walled steel tubes subjected to combinations of axial compression and external lateral pressure Cilmar Basaglia 1 , Dinar Camotim 2 , Nuno Silvestre 3 Abstract This paper reports the results of a numerical investigation on the buckling behavior of thin-walled steel tubes subjected to combinations of axial compression and external lateral pressure – these results are obtained by means of a GBT-based beam finite element formulation, recently developed by the authors, and also ANSYS shell finite element analyses. After providing a brief overview of the main concepts and procedures involved in performing GBT buckling analyses of circular cylindrical steel shells (such as cylinders/tanks and pipes), a parametric study is presented. It deals with the assessment of the buckling behavior of thin-walled steel tubes (radius-to-thickness ratio below 100) under various combinations of axial compression and external lateral pressure. In particular, the joint influence of the loading, length-to- radius ratio and radius-to-thickness ratio on the tube critical buckling load and mode shape is investigated. 1. Introduction The undersea or underground pipelines and jacket offshore platforms used in the petroleum industry are often formed by circular thin-walled steel tubes that are normally acted by combinations of axial compression and external lateral pressure. When such tubes exhibit slender cross-sections they are highly susceptible to the occurrence of local and/or global buckling phenomena, a feature that renders the numerical assessment of their structural behavior and strength a complex task (Teng & Rotter 2004). Various approaches have been used to assess the buckling behavior of circular cylindrical steel shells under hydrostatic external pressure. Probably the most popular of them consists of using the energy method to determine the critical buckling pressure (Arjomandi 2010). On the other hand, an analytical solution to obtain bifurcation/buckling loads of cylindrical tubes under combined external pressure and axial compression, using Donnell’s simplified equations, was developed, almost half a century ago, by Krishnamorthy (1974) – however, the major difficulty associated with the development and usage of closed form solution stems from (i) the presence of expressions with various undetermined coefficients and (ii) the mathematical determination of the number of lobes, i.e. , circumferential waves associated with the tube buckling mode. The numerical assessment of the structural response of circular cylindrical steel shells under hydrostatic external pressure also constitutes a complex task. Indeed, rigorous numerical analyses can only be performed by resorting to shell finite element models, a time-consuming 1 FEC, DES, University of Campinas. <[email protected]> 2 CERIS, DECivil, Instituto Superior Técnico, Universidade de Lisboa. <[email protected]> 3 IDMEC, DEM, Instituto Superior Técnico, Universidade de Lisboa. <[email protected]>
On the buckling behavior of thin-walled steel tubes subjected to combinations of axial compression and external lateral pressure
May 16, 2023
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