The role of aerodynamic forces in a mathematical model for suspension bridges

TL;DR

This paper investigates how aerodynamic forces affect suspension bridge stability, revealing they do not trigger torsional oscillations and proposing a combined structural and aerodynamic interaction as the cause of instability.

Contribution

It introduces a mathematical model incorporating aerodynamic forces and demonstrates their non-influence on torsional oscillation onset, offering a new explanation for bridge instability.

Findings

Aerodynamic forces do not influence torsional oscillation onset.

Instability arises from interaction between structural nonlinearity and aerodynamics.

Provides a new perspective on the origin of torsional instability.

Abstract

In a fish-bone model for suspension bridges studied by us in a previous paper we introduce linear aerodynamic forces. We numerically analyze the role of these forces and we theoretically show that they do not influence the onset of torsional oscillations. This suggests a new explanation for the origin of instability in suspension bridges: it is a combined interaction between structural nonlinearity and aerodynamics and it follows a precise pattern. This gives an answer to a long-standing question about the origin of torsional instability in suspension bridges.