On the Imperfection Sensitivity ofThin-Walled Frames

The analysis of two L-frames made up by channel sections subjected to various constraint conditions has been performed in order to determine their buckling and postbuckling behaviour. The analysis has been carried out in the framework of the asymptotic bifurcation theory, using a one-dimensional nonlinear elastic beam model able to account for warping. For each case considered, the first two buckling loads have been determined, together with the associated eigenmodes. For the frames showing an asymmetric postbuckling behaviour only the initial slope of the bifurcated path has been determined. In case of symmetric behaviour, also the secondary modes and the initial curvatures of the bifurcated path have been evaluated. The effects of small initial imperfections have also been studied in order to estimate the real load carrying capacity of the frames for all the cases examined.

[1]  C. Truesdell,et al.  The Non-Linear Field Theories Of Mechanics , 1992 .

[2]  V. Vlasov.  Thin-walled elastic beams , 1961 .

[3]  Bernard Budiansky,et al.  Theory of buckling and post-buckling behavior of elastic structures , 1974 .

[4]  Lei Zhang,et al.  - Warping and bimoment transmission through diagonally stiffened beam-to-column joints , 2005 .

[5]  Nicola Luigi Rizzi,et al.  A Parametric Postbuckling Analysis of an Asymmetric Two-Bar Frame , 1980 .

[6]  Dinar Camotim,et al.  Global buckling analysis of plane and space thin-walled frames in the context of GBT , 2008 .

[7]  Nicola Luigi Rizzi,et al.  The effects of warping on the postbuckling behaviour of thin-walled structures , 2011 .

[8]  Steen Krenk,et al.  Warping of joints in I-beam assemblages , 1991 .

[9]  John Roorda,et al.  Stability of Structures with Small Imperfections , 1965 .

[10]  L. Zubov.  Direct and inverse Poynting effects in elastic cylinders , 2001 .

[11]  Nicola Rizzi,et al.  The effects of warping constraints on the buckling of thin-walled structures , 2010 .

[12]  Giuseppe Ruta,et al.  A beam model for the flexural–torsional buckling of thin-walled members with some applications , 2008 .

[13]  Nicola Luigi Rizzi,et al.  Nonstandard Models for Thin-Walled Beams With a View to Applications , 1996 .

[14]  W. T. Koiter.  Over de stabiliteit van het elastisch evenwicht , 1945 .

[15]  A. H. Chilver,et al.  Frame buckling: An illustration of the perturbation technique , 1970 .