Experimental investigations on post-flutter performance of a bridge deck sectional model using a novel testing device

Abstract

This paper studies the flutter performances of a streamlined bridge deck sectional model using a recently developed testing device for large-amplitude free vibration test. The reported torsional vibration amplitude of the sectional model exceeds 15°, and higher vibration amplitudes can be achieved if desired. The flutter performances at various initial angles of attack α0, the hysteresis behavior, and the energy budget property of the flutter response are analyzed. Experimental results show that the sectional model exhibits divergent vibrations right after the critical flutter velocities for α0 = 0°, −3°, and −5°, while it performs limit cycle oscillations (LCO) after the critical flutter velocities for α0 = +3° and +5°. Hysteresis phenomena are observed for all tested angles of attack. Both the critical flutter velocity and the vibration amplitudes around the critical velocity may be affected by the initial impulse excitation exerted on the bridge deck. The vertical-to-torsional amplitude ratio decreases with increasing the vibration amplitude for a coupled LCO, while the opposite rule is observed for a divergent vibration. The energy dissipated by the mechanical damping accumulates continuously while the total mechanical energy varies non-monotonously with increasing time. This study is expected to deepen the understanding of the flutter responses of a bridge deck in the presence of nonlinear aerodynamic effects. The experimental results can also serve as a database for validating computational fluid dynamics procedures and nonlinear self-excited force models.