Presentation Title：Bridge Aerodynamics: The Next Frontiers

Speaker：Ahsan Kareem

Robert M. Moran Professor of Engineering

Member, US National Academy of Engineering

Distinguished Member of ASCE

President, International Association of Wind Engineering

Director, NatHaz Modeling Laboratory

Abstract：

Based on the general framework of the linear thin airfoil theory, aerodynamic and aeroelastic analysis of bridges has evolved over the last few decades in both time and frequency domains. For contemporary bridges with complex deck cross-sections, or increasing span-length, or both aeroelastic forces exerted on the evolving bridge deck cross-sections exhibit a clear departure from the linearized analysis framework that have been the basis of conventional schemes. Therefore, wind effects on bridges are not adequately represented by conventional linear analysis framework. This trend and observations of nonlinearity in the bridge aeroelasticity in wind-tunnel experiments have prompted the need for the development of a new general analysis framework attentive to both linear and nonlinear wind-bridge interactions. To address this challenge this seminar focuses on revisiting the current state- of-the art and identify the next frontiers and offer advanced computational and experimental tools to address these challenges.

The existing conventional linear and nonlinear analysis frameworks are first systematically reviewed with a focus on the study of the relationships among them and to understand their ability in simulating nonlinear unsteady aerodynamics. Several advanced low-dimensional modeling techniques, characterized by different levels of analysis of nonlinearity and unsteadiness, are then proposed. In this context, advanced models that work in tandem with computational models based on CFD and new experimental approaches will be discussed in light of predictive tools for buffeting; onset of flutter and post flutter instabilities; the role of turbulence; VIV; rain induced vibrations and strategies for enhancing the aerodynamics of bridge decks through shape optimization, slotted and multiple decks; cable deck interactions; strategies for the development of a performance based bridge design.