Study on Nonlinear Aerodynamic Characteristics of a Semi-Closed Box Bridge Deck Based on Coupled Amplitude Variation

Abstract

This paper explores the nonlinear characteristics of the self-excited aerodynamic forces of a semi-closed box deck section to perfect the theory of aeroelastic response analysis. A numerical wind tunnel model was established based on the computational fluid dynamics (CFD) method. The heaving-pitching coupled motion is realized by loading user-defined function (UDF) and dynamic grid technology. The self-excited aerodynamic forces varying with amplitude are identified and analyzed, and the reliability of the aerodynamic results obtained by numerical simulation is verified in the wind tunnel test. In the heaving-pitching coupled motion, the results show that the nonlinear characteristics of aerodynamic forces, especially the aerodynamic moment, are mainly affected by the pitching motion. The phenomenon of high-order harmonic energy transfer is observed with the increase in pitching amplitude, and the main component of high-order harmonic can be determined by the pitching amplitude. The contribution of heaving motion to aerodynamic forces nonlinear components is small, but its influence on nonlinear characteristics is complex. Small amplitude heaving motion plays a positive damping role in heaving-pitching coupled motion, and its scope and effect of positive damping action are affected by pitching motion. The extreme value heaving amplitude of positive damping action is observed in the aerodynamic lift.