Beam Pre-stress Loads and Lack-of-fit

Pre-stress and lack of fit loads are similar, but the definition differs. A pre-stress is considered as a force applied to the element at some position in the section relative to the neutral axis. A lack of fit is assumed to affect only the axial terms relating to the element. For a pre-stress of force and offsets of y and z the resulting nodal forces and moments are

For the lack of fit and the initial strain the nodal forces are respectively