Aeroelastic Analysis of Miradoiros Bridge in La Coruña (Spain)

In this paper the task of obtaining flutter derivatives and the computer evaluation of flutter speed was carried out for a cable stayed bridge with a main span of 658 m to be designed over the Ria of La Coruna in Spain. The bridge will be located in a very windy site and therefore some studies are required to find out the safety level against flutter aeroelastic phenomena. The set of eighteen flutter derivatives is important information required to carry out aeroelastic analysis aimed to identify the safety level of cable supported bridges against wind induced phenomena. In the case of flutter derivatives are the components of the aeroelastic damping and stiffness matrices that relate the lift, drag and moment forces to the vector of displacements and velocities of bridge deck. So far flutter derivatives are usually obtained by testing a reduced model of a deck segment in a wind tunnel. For doing that, two different alternatives exist: forced vibration approach or free vibration approach. In this occasion the free vibration approach with the sectional model of the deck supported by eight vertical and four horizontal springs was used and by carrying out tests for different speed flow. The complete set of eighteen coefficients A * i, P * i, H * i (i = 1,…6) was identified. Once flutter derivatives are obtained, flutter speed of the complete bridge can be calculated as it was explained in Jurado and Hernandez (2000), by the computational solving of a non linear eigen-problem which comes from the dynamic equilibrium equation for the deck.