STABILITY OF COLD-FORMED MEMBERS

A finite element method capable of predicting the buckling capacity of arbitrarily shaped thin-walled structural members under any general l oad and boundary conditions is presented. A rectangular thin plate ele ment with 30 degrees of freedom is used. The linear and geometric stif fness matrices for this element are derived explicitly using symbolic manipulation, thereby eliminating the need for the expensive process o f numerical integration. Further, the explicit form of the stiffness m atrices makes it easier to interpret the physical significance of the various stiffness terms. For sections composed of rigid flanges and fl exible web, a lower-order plate element is used in combination with a general beam-column element to form a super element for predicting dis tortional buckling modes. Formex formulation is used for the automatic generation of the data necessary for the analysis. Numerical examples of thin-walled structural members involving local, distortional and f lexural-torsional buckling modes are presented to demonstrate the accu racy, efficiency and versatility of the method.