Modeling of wind-induced vibration control and energy harvesting of traffic signal structures

Traffic signal support structures are slender, highly flexible, and lightly damped. Therefore, they are particularly susceptible to wind-induced vibrations, which result in repeated load stresses and fatigue failures. A tuned energy harvesting inerter damper (TEHID)is proposed to reduce wind-induced vibrations of traffic signal support structures and convert the wasted vibration energy into electricity. The TEHID creates a large inertia mass by converting the low-frequency vibration motion of the light head to a high-speed rotation thereby eliminating the need for a large physical mass and accommodation space required by the conventional tuned mass damper (TMD). This paper focuses on the nonlinear dynamics modeling of the wind-induced vibration control and energy harvesting system for traffic signal support structures. The traffic signal structure is modeled as an L-shaped beam with multi-segments and the TEHID is simplified as a three-element device consisting of a spring, a damper, and an inerter. The nonlinear equations and the boundary conditions governing the motion of the integrated vibration control and energy harvesting system are derived from the energy method and presented herein. Modal analysis is conducted and the derived natural frequencies and mode shapes are compared with the finite element simulation results to validate the analytical model.