Multistage Indicial Functions and Postflutter Simulation of Long-Span Bridges

Abstract

This article addresses a time-domain method for the postflutter analysis of long-span suspension bridges. The energy input properties of indicial functions (IFs) were first analyzed, and based on the findings, the concept of multistage IFs was brought forward to describe the nonlinear aeroelastic properties of bridge decks. The application of the multistage IFs to the nonlinear postflutter analysis entails resolution of two basic issues: smooth switching between groups of IFs and the integration of the mean wind loads. To avoid nonphysical transient responses that result from the abrupt involvement of a group of IFs, a strategy was developed that shows that groups of IFs participate in the aeroelasticity simulation simultaneously and independently; however, in this strategy, only two appropriate groups of IFs were engaged in denoting the aeroelasticity. To avoid double counting of the mean wind loads and to reflect the nonlinear properties of the loads correctly, separation of the pseudosteady effects from the aerodynamic loads denoted by IFs is suggested. The numerical example presented in this paper indicates that multistage IFs can be applied successfully to describe amplitude-dependent nonlinear aeroelastic effects and to conduct a time-domain postflutter analysis.