Values of Rayleigh Damping Coefficients in Non-Linear Dynamic Simulation (Aluminium)

I'm working with a model of a rigid catenary. The majority of the pieces are made of aluminium.

I know that I need the frequences in order to calculate propperly the coefficients but I only want an aproximation.

Could someone give me a typical range of this values?

I have tried 2 options:

- Both coefficientes = 0  -------> Very high vibration of the beam

- Both coefficientes = 1 -------> Very low vibration of the beam

Thank you.

SolidworksSimulation