抄録
The effective strength is defined as the strength of the equivalent continuum and derived for the rigidly connected lattice structures which subjected to the elastic buckling of constituent members. Main conclusions are as follows. The intensity of the effective strength of a rigidly connected truss is between one and four times of that of the pin jointed truss of the same members if the latter is stable. The instability pattern unit appears on a few of structural units and may change according to the stress states. For example, in-plane three-way lattice, in-plane parallel chord trusses, and a double-layer lattice plate are treated. By using the effective strength, the structural design becomes easy especially for rigidly connected trusses. Also, the next theorem has been proved and used. The matrix of the equilibrium equation for lattice structures in difference expression is the transposed matrix of that of the compatibility equation by changing the sign of the power of the shift operator, and vice-versa.
