Laboratory Simulation of Wind Vibrations in Roadside Structures

A method of frequency domain analysis in a laboratory is presented for simulating wind vibration affecting roadside transportation structures. The approach is intended to be complementary to or in lieu of a test in a large-scale wind tunnel. A full-size two-pole roadside sign was erected in a laboratory and attached to an electromechanical actuator. Dynamic response of the structure to an impact load from the actuator was converted into the frequency domain to determine a harmonic transfer function. Records of velocities from several actual strong wind events recorded in free-field conditions were combined with drag coefficients to predict the variation of pressure on the structure. Time histories of force that are to be imposed by the actuator on the signposts were developed using frequency response functions and converting them into the frequency domain by fast Fourier transform. Results show that nearly identical structural response of a roadside sign to simulated wind events can be obtained by using an actuator in a laboratory environment.