Modern Approaches to Modeling and Predicting Bridge Instabilities

Georgia State University Research Foundation, Inc., Atlanta GA

Investigators

Abstract

Modern pedestrian and suspension bridges and other large mechanical structures are designed using industry-standard packages, yet disastrous resonant vibrations are observed, necessitating multi-million dollar repairs. The main research objective of this project is to contribute to experimentally-validated dynamical systems approaches to understanding mechanisms of the dynamical instability of bridges and other complex mechanical structures interacting with pedestrian loads. The investigator develops predictive methods and engineering-scale, yet mathematically tractable, biomechanical models of humans' responses to bridge motion and vibrations of grandstands. He implements new dynamical assessment criteria to inform the development of software packages that can substantially improve both the design of new bridges and other mechanical structures and the assessment of serviceability of existing structures. Results from this research may lead to improved safety and economic benefits. Graduate and undergraduate students are engaged in the research of the project. This project contributes to a rigorous high-dimensional approach to the collective dynamics of non-smooth oscillators. It aims to improve existing inverted pendulum models of pedestrians' response to lateral bridge motion and to combine stability theory with multi-scale asymptotic analysis to reveal the true cause for the onset of pedestrian-induced bridge instabilities. It also targets a largely unexplored area in modeling and predicting bridge instabilities that includes bidirectional vertical interactions between humans and oscillating mechanical structures. At the interfaces between rigorous mathematical and computational theories, structural engineering, and human behavior, the project offers a transition from a rigorous mathematical theory to practical engineering analysis where predictive methods and pedestrian models can be used as "crash test dummies" to probe specific bridge designs. Graduate and undergraduate students are engaged in the research of the project. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.