Seismic Behavior of Cable-Stayed Bridges: Past, Present and Future

Abstract

Bridges require structural integrity and accessibility after an earthquake. However, over the years, these systems have proven to be highly vulnerable, as evidenced by the major earthquakes of San Fernando (1971), Loma Prieta (1989), Northridge (1994), Kobe (1995), and Taiwan (1999). In all of these events, it became clear that these structures, due to their strategic importance for inter- and intra-urban communication, must guarantee their usability for emergency communications after a severe event. Among the existing bridge typologies, cable-stayed bridges are undoubtedly a very important alternative, as they allow for the longest spans, along with suspension bridges. Due to their importance, it is desirable that bridges with spans exceeding 200 m be designed conservatively. As a general rule, it is common to require an elastic or near-elastic structural response for a design earthquake with a very low probability of occurrence. Therefore, in order to maintain an elastic response in structural elements and, at the same time, have a structure capable of dissipating energy, energy dissipation devices or base isolation can be used as passive seismic control strategies. Originally developed for military use, energy dissipation devices and base isolation quickly began to be adopted in the civilian sector to improve the seismic performance of buildings, and are now widely used, especially in bridges, buildings, and special structures. More recently, the use of active (semi-active, hybrid) control strategies is tentatively beginning to be implemented in these structures, primarily for vibration control in cables and tendons, which, as is well known, are very vulnerable to the effects of wind and rain.