Collapse of pressurized elastoplastic tubular members under lateral loads

The present work examines the collapse of tubular members subjected to lateral (transverse) quasi-static loading in the presence of uniform pressure. In particular, it investigates pressure effects on the ultimate lateral load of tubes and on their energy absorption capacity. External pressure is mainly considered, whereas internal pressure effects are also discussed. Tubes are modeled with shell finite elements, accounting for geometric and material nonlinearities. Relatively thick steel and aluminum tubes (D/t less than or equal to 50), which exhibit significant inelastic deformations, are considered. Two-dimensional cases are examined first, where lateral loading is imposed by either two rigid plates or by two opposite radial loads. Three-dimensional cases are also analyzed, where the load is applied either through a pair of opposite wedge-shaped indenters or a single spherical indenter. The results are presented in terms of load-deflection curves for different levels of pressure, and indicate that the presence of pressure has significant effects on tube response. Deformed shapes of tubes are depicted and discussed, and comparison with test data from non-pressurized pipes is conducted. Finally, simplified analytical models are presented for two-dimensional and three-dimensional load configurations, which yield closed-form expressions, compare fairly well with the finite element results and illustrate some important features of tube response in an elegant manner. (C) 2004 Elsevier Ltd. All rights reserved.