[Library of Congress, Washington, DC]
Wind can cause spectacular—and sometimes dangerous—vibrations in long-span bridges. One of the most critical phenomena is aeroelastic flutter, an instability that arises from the interaction between wind, structural motion, and aerodynamic forces. Understanding and preventing flutter is a key challenge in bridge engineering, especially as modern bridges become longer, lighter, and more flexible. Our research group investigates flutter and wind-induced vibrations in large civil structures, combining mechanics, aerodynamics, and innovative structural design.
Efficient simulations for flutter evaluation
A central part of our research is the study of flutter derivatives, which describe how aerodynamic forces change when a structure moves. These derivatives are essential for predicting flutter and understanding the physics behind wind–structure interaction. In our group, we obtain flutter derivatives using Computational Fluid Dynamics (CFD) simulations, allowing us to study complex geometries carry out extensive parametric studies.
Because high-fidelity CFD simulations can be computationally expensive, we also work on developing more efficient methodologies to extract flutter derivatives. One example is a multi-frequency excitation approach, where the bridge cross-section is forced to oscillate at several frequencies at the same time. This allows us to extract more aerodynamic information from a single simulation, significantly reducing computational cost while maintaining accuracy. Such methods are especially attractive for large parametric studies and early-stage design.
Flutter mitigation with distortionable bridge decks
Traditionally, flutter mitigation focuses on iterating on geometrical variations of the original geometry until a more stable version is found. In our work, we explore alternative and unconventional strategies that rethink how structures can safely interact with the wind. Rather than completely suppressing motion, we study how controlled deformation can be used to improve stability. This opens new possibilities for designing bridges that are both efficient and resilient.
One of our key design concepts is a flutter mitigation strategy based on allowing limited distortion of the bridge cross-section. By carefully connecting different parts of the deck, the structure gains an additional way to deform when exposed to strong winds. This extra motion can disrupt the aerodynamic mechanisms that lead to flutter and, when combined with damping, helps absorb energy from the wind instead of amplifying it. The result is a significant increase in the wind speed required to trigger instability.
