Reducing Fatigue in Wind-Excited Support Structures of Traffic Signals with Innovative Vibration Absorber

Abstract

Support structures of traffic signals are flexible, lightly damped structures that are highly susceptible to wind-induced vibration. The sustained large-amplitude deflections caused by these dynamic vibrations can result in fatigue cracking and failure. The proposed innovative vibration absorber reduces fatigue in support structures of traffic signals with the use of the mass of the signal head as a damped-vibration absorber. This novel concept, referred to as a signal head vibration absorber (SHVA), provides energy absorption in the form of increased damping to the lightly damped signal support structure. A prototype smart vibration absorber, envisioned as an inexpensive retrofit to signal support structures that were experiencing excessive wind-induced vibration, was tested in a full-scale laboratory experiment at the University of Connecticut. The SHVA was experimentally shown to have increased the damping in the signal support structure from 0.2% of the critical damping ratio to 10.1%. For steady state vibration, this difference is equivalent to a 98.3% reduction in the response and virtually eliminates any deflections. A single SHVA can be applied to a wide range of signal support structures while still achieving reasonable performance. The SHVA can change the way vibration in traffic signal support structures is mitigated.