in structural mechanics, the linear deviations of points in a stucture and the angles of rotation of sections and also the combinations of these quantities (mutual displacements) that characterize the changes in the position of the structure caused by loading forces, temperature effects, or settling of the supports. Displacements are determined when evaluations are made of the rigidity and related service qualities of structures. They are obtained as auxiliary quantities in the design of statically indeterminate systems and are used in estimating the stability and the vibration of structures.
To determine displacements in rod systems, Mohr’s formula is usually used. In general, the dependence of displacements on the bending moments, longitudinal forces, and transverse forces that appear in the elements of the system under the action of the effective loads are taken into account. In some cases, only the effect of the bending moments (in beams and bedplates) or the longitudinal forces (in girders) is considered.