The application of the prestressing technique to steel structures makes it possible to increase the load-carrying capacity as well as to extend the elastic region of existing steel bridge systems. The aim of this particular research is not only to develop a method of nonlinear analysis of prestressed composite plate girders based on the incremental deformation method, but also to demonstrate the feasibility of applying the prestressing technique to the strengthening of existing steel bridges. The accuracy of the proposed analysis was verified by comparisons with test results on full scale prestressed composite plate girders with various levels of prestressing, eccentricity of draped tendons, and differing tendon material properties. Using this method it was possible to predict the ultimate response and failure modes of the various prestressed composite plate girders. The performance of different types of prestressed composite plate girders under static loading was analytically evaluated for the strengthening of existing steel bridge systems. Furthermore, a method of performance evaluation related to the load-carrying capacity and deflection control of the prestressed composite plate girders with external tendons is proposed, based on consideration of the analytical results, with some optimum geometric and material parameters. Finally, the design concept of prestressed composite plate girders with external tendons is discussed in relation to the construction of new bridges, and in the strengthening of existing bridges.
prestressed composite plate girder
external tendon
mechanical behavior
bridge strengthening
design concept