Investigation of elevated global cable forces in prestressed concrete cable-stayed bridges during service conditions

This study investigates the excessive cable forces observed in a double-tower prestressed concrete (PC) cable-stayed bridge during its operational phase. Comparative analysis between field-measured data and design specifications reveals that the actual bearing capacity of multiple stay cables significantly exceeds the code-specified allowable limits, compromising structural safety requirements. A finite element model was established using Midas Civil software, leveraging operational monitoring data to simulate the bridge construction process. The analysis specifically investigated the effects of girder self-weight variations, prestressing force adjustments, and main beam alignment changes on cable force distribution patterns. The numerical analysis demonstrates that beam self-weight augmentation and main beam alignment alterations collectively account for 62.3 % of the total measured cable force increment, representing the primary contributing factors. In contrast, the impact of prestressed over-tension and subsequent loss (maintaining less than 10 % variation) on cable forces was found to be statistically insignificant, suggesting these parameters have minimal influence on the overall cable force distribution pattern.