Effects of prestress on strains and deflections in pretensioned beams

In this research, nonlinear structural analysis along with finite element analysis were carried out for a pretensioned concrete beam at different levels of pretension in order to examine the effect of the change in the tendon force on the geometric stiffness of the beam. Several results were obtained for deflection, horizontal displacement and surface strains to investigate how they are affected by the level of pretension under the application of the same load in each case. These computations were compared with the tendon force to conclude whether they can be used to estimate the pretension level by means of simple measurements. The purpose was to develop a methodology for quantifying the prestress losses by taking advantage of the dependence of the prestressed concrete beam stiffness on the tendon force.