Ultimate Behaviour of Externally Prestressed Concrete Bridges

This paper presents a numerical model for analysis of the ultimate behaviour of externally prestressed concrete bridges. The proposed model can analyse simply supported or continuous, monolithic or segmental bridges, with external unbonded prestressing and/or internal bonded prestressing. The model calculates the real stress in the prestressing steel at any load level for these types of structures. Some codes recommend constant values or approximate formulas for the increase of stress of the prestressing steel at ultimate limit state. These values are sometimes too conservative or unreasonable high. This article describes the numerical model and some examples of externally prestressed bridges analysed up to failure by bending.