Progressive collapse analysis of thin-walled box columns

Box columns are often used as main strength members of various types of thin-walled structures such as ships, ship-shaped offshore structures, and aerospace structures. Until and after the ultimate limit state is reached, box columns exhibit highly nonlinear structural behavior in terms of geometrical and material aspects. In particular, the effects of local buckling, global buckling, and their interaction play a significant role in the resulting consequences of box columns under extreme actions. In order to calculate the maximum load-carrying capacity of box columns, it is thus highly required to perform the progressive collapse analysis to take into account progressive failures of individual components and their interacting effects. The aim of the present study is to demonstrate a method that is useful for the progressive collapse analysis of thin-walled box columns in terms of computational efficiency and accuracy. Theoretical outline of the method is addressed. Short, medium and long box columns in length are studied in terms of interacting effects between local component failure modes and global system failure modes. The effect of unloaded edge conditions of individual plate elements is also studied. A comparison of the method with more refined nonlinear finite element method computations is made. © 2007 Elsevier Ltd. All rights reserved.