The Elastic Lateral Stability of Trusses

The article gives an approximate analysis, using the energy method, for the elastic stability out of their plane of trusses with outstanding compression chords, the tension chord being held in position. Previous discussions of this problem have usually considered it in terms of the stability of the compression chord as a member subjected to various elastic restraints. In the present treatment, the truss is considered as a whole, account being taken of the flexural and torsional rigidities of all the members, and of partial restraint of the tension chord against twisting. The analysis is interpreted in relation to a number of common arrangements of vertical and diagonal web members. The analysis is derived for a truss in which the compression chord is of uniform section, carrying a uniform thrust, but the use of some of the results as approximate criteria of stability for non-uniform conditions is also discussed.