Wind-Induced Lock-In Excitation of Tall Structures

by Kenny C.S. Kwok, Lect.; School of Civ. Engrg., Univ. of Sidney, New South Wales, Sidney 2006, Australia,
William H. Melbourne, Prof. of Fluid Mech.; Dept. of Mech. Engrg., Monash Univ., Victoria, Australia,

Serial Information: Journal of the Structural Division, 1981, Vol. 107, Issue 1, Pg. 57-72

Document Type: Journal Paper


Circular and square tower models were tested in a boundary layer wind tunnel. At close to the critical reduced velocity and particularly at low values of structural damping, displacement dependent lock-in excitation was found to cause large increases in cross-wind displacement response, especially for the circular tower, in a suburban type wind model. Critical cross-wind response amplitudes were determined from the response characteristics. These response amplitudes represent the level of cross-wind response of a structure above which the response can not be accounted for by the random wake excitation process and that lock-in excitation is significant. A prediction procedure, which consists of a random excitation model and a sinusoidal lock-in excitation model, is described. Cross-wind response predicted by these models agreed well with the measured response.

Subject Headings: Wind forces | Excitation (physics) | Displacement (mechanics) | Boundary layers | Wind tunnel | Tunnels | Wind speed | Damping

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