Computational Fluid Dynamics Investigation of High Mast Illumination Poles: Influence of Light Fixtures

Details

• Creators:
  Junge, Briceson ; Bennett, Caroline ; Collins, William ; Li, Jian ; Ewing, Mark
• Corporate Creators:
  University of Kansas. Dept. of Civil, Environmental and Architectural Engineering
• Corporate Contributors:
  Kansas Department of Transportation. Bureau of Research ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  Aerodynamic Force Data Analysis Evaluation Failure Fluid Dynamics Fluid Mechanics Lighting Lighting Equipment Luminaires Simulation
• Publication/ Report Number:
  KS-26-01
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Kansas
• Edition:
  Final Report: September 2019 – August 2022
• Corporate Publisher:
  Kansas. Dept. of Transportation. Bureau of Research
• Abstract:
  High Mast Illumination Poles (HMIPs) are lighting towers that are taller than 55 ft (16.8 m) and are typically located along highways and rest stops. In March 2019, a wind event, referred to as a “bomb cyclone,” caused several HMIPs in Kansas to excite and experience large-amplitude deflections on the order of several feet called “lock-in” behavior. Lock-in behavior is when the frequency of vibration matches a natural frequency of the structure and excess deformations will be observed. Pole vibrations can be caused by multiple wind actions and wind-structure interactions, including aeroelastic phenomenon like vortex shedding. Following the bomb cyclone event in 2019, the poles were inspected, and cracks were identified around the handhole openings in several of the structures. These poles were taken out of service having only been in service for approximately one year. Their premature failure caused significant concern. New, LED luminaires had been implemented with the construction of these poles. The Kansas Department of Transportation (KDOT) sought to learn if selection of LED luminaires (rather than older-style incandescent fixtures) had any influence on the behavior observed during this event. The goal of this research project was to examine and compare the behavior of wind flow past LED and incandescent luminaires used in Kansas using computational fluid dynamics (CFD) modeling. Two-dimensional models were developed in Abaqus/CFD 2016 representing a projection of the full lighting assembly at the top of an HMIP. Simulations were created for each luminaire type on assemblies including three and four fixtures. The angle of wind relative to the light fixture and wind speed were varied throughout the simulations. Three-fixture simulations used wind angles of attack of 0, 30, and 60 degrees and four-fixture simulations used wind angles of attack of 0, 22.5, and 45 degrees. All assemblies and wind angles of attack were simulated for wind speeds of 15 (6.7), 25 (11.2), 30 (13.4), 35 (15.6), and 45 mph (20.1 mps). Time histories of the resulting forces on the lighting assemblies in the along-wind and cross-wind directions were extracted from the models. Power spectral density (PSD) curves were developed, identifying the dominant frequencies in the time-history data. The peaks in the PSD curves were extracted and compared with the first three natural frequencies of four representative HMIP archetypes used in the state. Natural frequencies of those four HMIP archetypes were determined using structural models of the poles using Abaqus/CAE 2017. To account for uncertainties in the analyses, ±10% bounds around each natural frequency were used when comparing the peaks in the PSD data with structural natural frequencies. When a peak fell within these bounds, it was treated as a “hit,” having potential to excite that natural frequency mode and produce lock-in behavior. Hit counts were used to evaluate the data and compare each fixture type, angle of wind attack, and wind speed.
• Format:
  PDF
• Funding:
  C2153
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:44df90cebfc4b7f7722c793569eceaa951f3762deb9a6b6729bc4fe2ffe5e6c12a21053a6b33012374aaf9954b68d8baf144e43a2bace95e939b4422ee18950d
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/88858/dot_88858_DS1.pdf
• File Type:
  [PDF - 8.09 MB ]