Fatigue Analysis of a Cable-Stayed Bridge under Wind Loads Combined with Traffic Effects

This paper presents a comprehensive and systematic framework for analyzing the fatigue effects on cable-stayed bridges subjected to the combined action of traffic and wind. The methodology integrates structural modeling, realistic load characterization, and fatigue assessment procedures to provide a reliable tool for evaluating the long-term performance of such bridges. The approach was applied to the Sidi-Maarrouf cable-stayed bridge in Casablanca, Morocco, which served as a representative case study. A detailed finite element model of the bridge was developed in ANSYS Mechanical, where stress influence surfaces of the stay cables were established. Realistic input data were incorporated: traffic loads derived from recorded vehicle flows at the bridge entrances, and wind effects computed from meteorological measurements recorded at the Mohamed V Airport weather station, located close to the bridge site. Special attention was devoted to the analysis of wind-induced vibrations, which were shown to have a limited impact on the overall structural response. Fatigue analyses were subsequently performed to quantify cable damage under two scenarios: traffic loading alone and combined traffic–wind actions. The results revealed that wind-induced fatigue is negligible compared to traffic-induced effects. Beyond this case study, the proposed framework provides a systematic approach to evaluate fatigue performance. It includes a practical procedure to identify wind velocity thresholds leading to significant fatigue damage, as well as the construction of safety factor variation curves that can assist in decision making. These contributions demonstrate the applicability of the framework to other cable-stayed bridges, supporting both design improvements and maintenance strategies.