The Determination of the Critical Loads of Plane Frames

The critical load of a plane frame is that at which the resistance offered by the frame to any random disturbance is nil. For this state the stiffness matrix corresponding to all possible disturbances is singular. The elements of this matrix are quantities used in the moment distribution methods pieviously proposedthe moment distribution methods pieviously proposed and for most loads, not close to the critical load, the stability, or otherwise, of the frame is determined by inspection without performing the moment distribution. For loads near the critical load the problem is transformed into the calculation of the largest latent root of an allied matrix. This calculation is simpler than moment distribution.

S. J. McMinn