16 Gennaio, 2018 15:15

Sezione di Analisi

Torsional instability in two nonlinear isolated models for suspension bridges

Alessio Falocchi, Politecnico di Milano

Aula seminari 6° piano

Many observations throughout history have recorded that torsional instability afflicts suspension bridges. In the scientific community there is not an unanimously accepted explanation about the origin of instability. We present two new dynamical isolated models derived from variational principles and we study two nonlinear hyperbolic partial differential equations, involving the vertical displacement and the torsional rotation of the deck.
In the first model we consider three different nonlinearities to model the hangers slackening mechanisms; in the second one we deal with the nonlinearities due to the geometric configuration of the main cables, supposed deformable, and we prove the existence and uniqueness of a weak solution. We show some numerical experiments, highlighting the torsional instability phenomena with respect to the longitudinal modes excited. Our results suggest that the origin of the instability is hidden in the nonlinear behavior of these structures.