Study On The Flutter Derivatives Of The π-shaped Girder Section Based On Numerical Simulation

The Flutter stability analysis is essential when studying the wind-induced vibrations of bridge. Bridge Flutter is a self-excited divergent vibration, when it happens, there would be a devastating disaster. Flutter derivatives is the core of most of the existing methods on flutter analysis, which is also the key parameters determining the critical flutter speed. This paper focused on the flutter derivatives of π-shaped cross section, doing the following work:First, this paper introduced the bridge wind-induced effects briefly, and reviewed the flutter stability research history as well as the latest developments, made a summary analysis to the recognition theories and methods of bridge flutter derivatives providing a theoretical basis for the wind tunnel test and numerical simulation of this paper, introduced the basic theories of the computer fluid dynamics, found the appropriate numerical algorithms and models for this paper’s study via analyzing those theories.Then, made out the flutter derivatives of a π girder section with air nozzles through the numerical simulation and wind tunnel tests separately, compared the two results finding that four main flutter derivative values are in good agreement, but the four deputy flutter derivatives had slightly larger differences in individual conditions. Generally speaking, the numerical algorithms on making out the flutter derivatives of π-shaped cross-section for this paper is available. Analyzed the influence of wind attack angle on the flutter derivatives of π-shaped cross-section through the numerical simulation results.Finally, proposed a size coefficient φ of π-shaped cross section which is defined as the ratio of the π-shaped sectional width B and the distance L between the legs. Numerically calculated four π-shaped cross-section studying the influence of the size coefficient φ on the flutter derivatives. The results showed that under different wind-attack angles and different wind speeds, φ affects the flutter derivatives differently, thus we should study each flutter derivatives with the change of φ in connection with the wind attack angle and wind speed. At the same wind speed, φ affects almost nothing for A1, A2 andA4. When the wind attack angle is 0 °, + 3 °, + 5 °, φ has no effect onH4 either. In other conditions, the size coefficient φ of π-shaped cross-section has different effects on the five other flutter derivatives.