Experimental Investigation on the Nonlinear Coupled Flutter Motion of a Typical Flat Closed-Box Bridge Deck

Experimental Investigation on the Nonlinear Coupled Flutter Motion of a Typical Flat Closed-Box Bridge Deck

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The nonlinear post-flutter instabilities were experimentally investigated through two-degree-of-freedom sectional model tests on a typical flat closed-box bridge deck (width-to-depth ratio 9.14).Laser displacement sensors and piezoelectric force balances were used in the synchronous measurement of dynamic displacement and aerodynamic force.

Beyond linear flutter boundary, the sectional model exhibited heave-torsion coupled limit cycle oscillation (LCOs) with an unrestricted increase of stable amplitudes with reduced velocity.The post-critical LCOs vibrated in here a complex mode with amplitude-dependent mode modulus and phase angle.Obvious heaving static deformation was found to be coupled with the large-amplitude post-critical LCOs, for which classical quasi-steady theory was not applicable.

The aerodynamic torsional moment and lift during post-critical LCOs were measured neflintw-r6mpw through a novel wind-tunnel technique by 4 piezoelectric force balances.The measured force signals were found to contain significantly higher-order components.The energy evolution mechanism during post-critical LCOs was revealed via the hysteresis loops of the measured force signals.