Full-scale investigation of wind-induced vibrations of mast-arm traffic signal structures.

Details

• Creators:
  Sinh, Hung Nguyen ; Riedman, Michelle ; Letchford, Christopher ; O'Rourke, Michael
• Corporate Creators:
  Rensselaer Polytechnic Institute. Dept. of Environmental and Civil Engineering
• Corporate Contributors:
  United States. Dept. of Transportation. Research and Innovative Technology Administration ; United States. Federal Highway Administration
• Subject/TRT Terms:
  Cantilevers Fatigue (Mechanics) Field Tests Sign Supports Stresses Traffic Signals Turbulence Vibration Vortex Shedding Wind
• Publication/ Report Number:
  C-10-07
• Resource Type:
  Tech Report
• Geographical Coverage:
  New York
• Corporate Publisher:
  New York (State). Dept. of Transportation
• Abstract:
  Because of their inherent
  
  fl
  
  exibility and low damping ratios, cantilevered mast
  
  -
  
  arm
  
  tra
  
  ffi
  
  c signal structures are suscepti
  
  b
  
  le to
  
  wind
  
  -
  
  induced vibrations.
  
  These vibrations
  
  cause stru
  
  ctural stresses and strains to develop in a cyclical fashion which can
  
  lead
  
  to reduced service life due to fatigue and, in extreme cases, full collapse.
  
  In 2001, after the collapse of several of these
  
  structures throughout the United
  
  States, American Assoc
  
  iation of State Highway and Transportation O
  
  ffi
  
  cials (AASHTO)
  
  code standards were updated to include fatigue provisions for tra
  
  ffi
  
  c signal supporting
  
  structures.
  
  In New York State, there is
  
  particular concern regarding structures
  
  spanning longer than 14 me
  
  ters which currently do not meet these updated fatigue
  
  provisions. To address this concern, a full
  
  -
  
  scale experiment was conducted using an
  
  existing 25 meter mast
  
  -
  
  arm tra
  
  ffi
  
  c signal
  
  structure, located in Malta, NY, in which
  
  the response of the structure was
  
  observed in relation to in
  
  -
  
  situ wind conditions.
  
  In previous studies, high
  
  -
  
  amplitude vertical vibrations of mast
  
  -
  
  arm tra
  
  ffi
  
  c signal
  
  structures have been shown to be due to
  
  vortex shedding, a phenomenon in
  
  which alternatingly shed, low
  
  -
  
  pressure vortices in
  
  duce oscillating forces onto the
  
  mast
  
  -
  
  arm causing a cross
  
  -
  
  wind response. When the frequency of vortices being shed
  
  from the mast
  
  -
  
  arm corresponds to the
  
  natural frequency of the structure, a resonant
  
  condition is created. The resonant condition causes the l
  
  ong
  
  -
  
  lasting, high
  
  -
  
  amplitude
  
  vibrations
  
  ,
  
  which may lead to the fatigue failure of these structures.
  
  Turbulence in the approach
  
  fl
  
  ow is known to
  
  a
  
  ff
  
  ect the cohesiveness of vortex
  
  shedding. Results from this full
  
  -
  
  scale experiment indicate that the surrounding
  
  terrain conditions, which a
  
  ff
  
  ect the turbulence intensity of the wind, greatly in
  
  fl
  
  uence
  
  the likelihood of occurrence of long
  
  -
  
  lasting, high
  
  -
  
  amplitude vibrations and also
  
  impact whether reduced service life due to fatigue is likely to be a concern
  
  
• Format:
  PDF
• Collection(s):
  University Transportation Centers US Transportation Collection
• Main Document Checksum:
  urn:sha256:1f8d36cf75525efbe119c3a56fa710088974adbb8749606b3ad5b753adcab5d5
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/28330/dot_28330_DS1.pdf
• File Type:
  [PDF - 8.14 MB ]