THE CALCULATION OF MODAL CROSS-SECTION PROPERTIES FOR USE IN THE GENERALIZED BEAM THEORY

A previous paper presented a method of analysis for any open unbranche d thin-walled section considering both rigid body movement and cross-s ection distortion (including local buckling). It described briefly the calculation procedures required in order to obtain section properties related to each of a number of cross-section distortion modes. These properties were generally calculated using first-order theory. This pa per describes in full how second-order theory can be used to calculate the section properties for all modes, including each of the four rigi d body modes. In the process of developing the second-order generalize d beam theory, additional section properties evolve which enable the f irst-order equilibrium equation to be modified to consider second-orde r elastic critical load problems.