Determination of Flutter Derivatives of Bridge Decks By Covariance-driven Stochastic Subspace Identification

In this paper, the covariance-driven stochastic subspace identification technique (SSI-COV) was presented to extract the flutter derivatives of bridge decks from the buffeting test results. An advantage of this method is that it considers the buffeting forces and responses as inputs rather than as noises. Numerical simulations and wind tunnel tests of a streamlined thin plate model conducted under smooth flows by the free decay and the buffeting tests were used to validate the applicability of the SSI-COV method. Then, the wind tunnel tests of a two-edge girder blunt type of industrial-ring-road (IRR) bridge deck were conducted under smooth and turbulence flows. The flutter derivatives of the thin plate model identified by the SSI-COV technique agree well with those obtained theoretically. The results obtained for the thin plate and the IRR bridge deck are used to validate the reliability and applicability of the SSI-COV technique to various wind tunnel tests and conditions of wind flows. The results also show that for the blunt-type IRR bridge deck, the turbulence wind will delay the onset of flutter, compared with the smooth wind.