Virtual distortions are incompatible deIormations imposed on structures (e. g. , by nonhomogeneous heating or by local imperIections) causing a compatible state OI deIormation (initial deformations) and a selI-equilibrated state OI stress (initial stresses). The theory OI virtual distortions provides an eIIicient tool which can be used to treat many problems that diIIer Irom the physical point OI view. Thermal stresses, material deIects, residual stresses in plasticity are examples OI problems that can be analysed emploing the virtual distortions approach, where the temperature Iield, dislocations and plastic distortions (permanent plastic deIormations) are described by virtual distortions. The presented approach allows the development OI eIIicient computational methods Ior numerical analysis OI such problems. States OI compatible deIormations and selI-equi1 ibrated stresses caused by virtual distortions in homogeneous and compound (biphase) bodies are analysed in the Iirst part OI the book. The results OI these considerations are explored in the next two chapters. The Iormulation OI the approach discussed in Chapter 1 and based on continuum mechanics was presented previously in the papers [5, 17] while its application to the analysis OI skeletal structures was discussed in [47].