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.

Aerodynamics of Highway Sign Structures: From Laboratory Tests and Field Monitoring to Structural Design Guidelines

“…(1) reducing the blockage area without compromising the visibility (e.g., reduce area of flashing lights and material surrounding the lights); (2) including vibration dampers common to larger structures (Christenson and Hoque 2011;Giaralis and Petrini 2017);…”

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

“…Aero-dynamic damper plates were also developed and implemented because of their low cost and easy installation to mitigate the galloping-induced vibration of mast arms [11]. Moreover, tuned mass dampers (TMDs) were demonstrated to be capable of effectively reducing vibrations of traffic signal structures [12,13]. However, traditional TMDs need a large mass to achieve effective vibration reduction, which requires a large space to accommodate and adds additional weight to the flexible structures.…”

Optimisation of the Parameters of a Vibration Damper Installed on a Historic Bridge

“…One of them can be the use of a device such as a dynamic absorber, which has been used for over a century [1,2], especially in the case of dynamic loads. Numerous ways and means of pre-emptively preventing harmful vibrations are already known, and research on the parameters of optimal absorbers continues for both deterministic [1][2][3][4][5][6][7][8][9][10][11] and stochastic excitations [13][14][15][16][17][18][19][20][21][22][23]. Various types of vibration absorbers are used to reduce vibration levels in different engineering structures, such as bridges [3], tall buildings [4], chimneys [5], pipeline structures [6], traffic signal structures [7], wind turbines [12], thinwalled structures [13] etc.…”

“…Numerous ways and means of pre-emptively preventing harmful vibrations are already known, and research on the parameters of optimal absorbers continues for both deterministic [1][2][3][4][5][6][7][8][9][10][11] and stochastic excitations [13][14][15][16][17][18][19][20][21][22][23]. Various types of vibration absorbers are used to reduce vibration levels in different engineering structures, such as bridges [3], tall buildings [4], chimneys [5], pipeline structures [6], traffic signal structures [7], wind turbines [12], thinwalled structures [13] etc. The absorbers play a special role because they can be used during the construction of a structure and also when unsatisfactory dynamic properties appear during its operation.…”

“…The parameters of absorbers should be optimised. Many parameters can be adopted as an optimization criterion, for example, the minimum vibration variance [15], the minimum of an excess factor [8], the minimum fatigue of the material [7] etc. The optimisation of A b s t r a c t The paper presents theoretical analyses of renovating a historical bridge in order to decrease stresses.…”