2ND-ORDER GENERALIZED BEAM THEORY

This paper introduces the second-order terms associated with geometric nonlinearity into the basic equation of Generalised Beam Theory. This gives rise to simple explicit equations for the load to cause bucklin g in individual modes under either axial load or uniform bending momen t. It is then shown how the explicit procedure can be extended to cons ider the interaction between local, distortional and global buckling m odes. More general load cases require the use of numerical methods of analysis and the finite difference method offers a suitable procedure. The success of Generalised Beam Theory for a wide range of situations is demonstrated by comparing the results obtained using it with both test results and other analyses. It is shown that it offers particular advantages in the analysis of buckling problems in cold-formed sectio ns.