An Experimental Investigation of the Aeroelastic Instability of the Suspension Bridges.

In the previous report the authors suggested that the flutter speed of a two-dimensional suspension bridge could be estimated by the linearized flutter theory including the nonsteady linearized aerodynamic force terms, the values of which were obtained from a sectional partial model experiments. In this report that linearized flutter equations for a three-dimensional suspension bridge are given, which are derived from the strip theory as in the case of an aircraft. The results of wind tunnel experiments with a complete threedimensional model and a partial sectional model are given. Comparison of these results with the values calculated from the equations stated above using the experimental nonsteady linearized aerodynamic force terms shows considerably good agreement. Therefore it can be concluded that we may be able to estimate the flutter speeds of three-dimensional suspension bridges using the flutter equations with the measured nonsteady aerodynamic forces.