Finite element modeling of concrete beams prestressed with external tendons

In this study, a numerical model based on the finite element method incorporating an arc-length solution algorithm for materially and geometrically nonlinear analysis of concrete beams prestressed with external tendons is established. The second-order effects are taken into account. The effects of external tendons are expressed by equivalent nodal loads of the beam element and therefore analysis of externally prestressed concrete beams can be conducted with the ordinary bonded concrete beams. The section tangent stiffness matrix is derived by the layered approach, and then the nonlinear beam flexural theory is utilized to determine the element tangent stiffness matrix. An updated normal plane arc-length solution algorithm is used to trace the nonlinear response of the beams from zero loads up to ultimate loads. This algorithm can deal well with the changes of response during loading, so that the possible limit points on the load–deflection response prior to the ultimate limit state can be easily passed. Results predicted by the analysis are in good agreement with the experimental data.