Acta Scientiarum Polonorum

An incremental solution of a member in bending and compression by displacement method with shear force impact is presented, wherein individual incremental steps, both the geometrical characteristics of the cross-section and the position of the neutral axis, can be changed. Functions of loads, internal forces and displacements are represented by trigonometric series. In every load step internal forces and deformation state is memorised, therefore history of the load and stiffness is taken into account. This solution is useful both in static calculations of structures being strengthened as well as in structures, in which degradation of stiffness under load occurs as a result of wall stability loss. The member may be loaded by uniformly distributed load, any number of concentrated forces and nodal moments.