A finite element approach for modeling dynamic effects of prestressing in concrete beams

Prestressed concrete structures are widely utilized in civil engineering due to their superior structural efficiency and load-carrying capacity. However, long-term losses in prestressing forces can compromise both structural integrity and service performance. This study develops a finite element model to assess the impact of prestressing force on the natural frequencies of simply supported beams. The model accounts for the combined effects of axial compression and the physical characteristics of the tendon, including variations in eccentricity and geometric profile. Validation against experimental results from the literature demonstrates strong correlation, particularly for the first and second vibration modes, with average discrepancies of 2.48 and 2.68%, respectively. Numerical simulations also reveal that the influence of prestressing is most pronounced during the early stages of loading, with frequency shifts tending to stabilize as the applied load nears critical levels. The proposed framework offers a valuable complementary approach for the indirect estimation of losses in prestressing forces.