TREATMENT OF INITIAL DEFORMATIONS IN THE INTEGRATED FORCE METHOD

A new force finite element formulation, termed the Integrated Force Me thod, has been developed in recent years for the structural analysis. In the Integrated Force Method all independent forces are treated as u nknown variables which are calculated by simultaneously imposing the f orce equilibrium and strain compatibility. The Integrated Force Method is extended in this study for the treatment of initial strains. Initi al strains are incorporated into compatibility conditions through the vector of initial deformations. A general expression for the vector of initial deformations is derived by discretizing the expression for th e complementary potential energy of the structure. Two special cases o f initial strains are analyzed in detail: (i) thermal strains and (ii) support settlements. The vector of initial deformations due to therma l loadings is derived by introducing expressions for thermal strains i nto the general expression, and that due to support settlements is der ived directly by equating the work done by external and internal force s, respectively. Two example problems with available analytical soluti ons are solved using the present developments. A good agreement of res ults with analytical solutions is observed.