Effects of prestressing on the structural behavior of cable-stayed bridges

Abstract

In recent decades, mostly thanks to their aesthetic appearance and excellent structural characteristics, cable-stayed bridges have gained increasing popularity. The main principle of cable-stayed bridges is to counteract the dead loads applied to the deck of the bridge by post-tensioning the stay cables and transferring the loads to the ground through the pylons. Optimum distribution of the post-tensioning stay cable forces is said to be one of the most difficult and primordial parameters to design in a cable-stayed bridge project. Indeed, the choice of the stay cable pattern and the stay cable forces impacts grandly the structural behavior of the whole structure. Through history, several cablestayed bridges - even in recent years like the Chirajara bridge in 2018 - have collapsed because of poor design. Hence, knowing exactly the influence of prestressing on one cable-stayed bridge design can be rewarding and welcome.

The Masters thesis in question attempts to give a perhaps first study of the influence of prestressing on the structural behavior of cable-stayed bridges. Finite element modeling, on which are conducted non-linear static and nonlinear modal analyses, completed by structural experiments are used to prove the results obtained. The variables chosen for this parametric study are the number of stay cables on the structure, the tension of the stay cables, and the stay cable pattern - harp and semi-fan patterns. By changing the values of these parameters for the same design of a cable-stayed bridge, it was possible to study their influence on the structural behavior of the whole structure.