A simple beam-like finite element model for the analysis of concrete beams prestressed with unbonded tendons

Abstract

This paper presents a new beam-like finite element model for the analysis of the mechanical response of a reinforced concrete beam prestressed with unbonded curved tendons under short-term static loading. To develop a numerically efficient and computationally inexpensive model while still capturing the most important characteristics of the beam’s deformation, only the material nonlinearity is fully considered, as suggested by current engineering standards, whereas the kinematics are consistently linearized in the model. To ensure successful completion of the analysis even for statically indeterminate structures, where the effect of concrete softening may start well before the point of the beam’s final collapse and could result in convergence issues, localisation of deformations and concrete softening under compression are treated according to a well-established crack-band principle. Reliability and efficiency of the developed model are proven on the examples of simply supported and continuous beams, for which well-documented experimental results are available in literature. The model provides the user with a quick and easy-to-understand finite element tool for practical use in design of prestressed structures.