Thermal gradients in Southwestern United States and the effect on bridge bearing loads : final report.

Details

• Creators:
  White, Leanne ; Ryan, Keri L. ; Buckle, Ian G.
• Corporate Creators:
  University of Nevada, Reno. Solaris University Transportation Center ; University of Nevada. Dept. of Civil & Environmental Engineering
• Corporate Contributors:
  United States. Department of Transportation. University Transportation Centers (UTC) Program
• Subject/TRT Terms:
  • Bearing capacity
  • Bridge bearings
  • Bridge design
  • Environmental impacts
  • Girder bridges
  • Heat flow
  • Prestressed concrete bridges
  • Temperature gradients
  • Thermal analysis
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States;Nevada;Las Vegas (Nevada)
• Edition:
  Final report
• Corporate Publisher:
  University of Nevada, Reno. Solaris University Transportation Center
• Description:
  Thermal gradients became a component of bridge design after soffit cracking in prestressed
  
  concrete bridges was attributed to nonlinear temperature distribution through the depth of
  
  the bridge. While the effect of thermal gradient on stress distributions has been previously
  
  investigated in concrete bridges, less research has been done investigating the effect on
  
  bearing loads. The climate condition of the southwestern portion of the United States may
  
  cause larger thermal gradients than recommended by AASHTO LRFD Bridge Design
  
  Specifications.
  
  The main objective of this study was to evaluate the effect of thermal gradients in the
  
  southwestern region of the United States on bearing design. This study consisted of two
  
  parts, heat flow analysis using long-term meteorological data and two case study bridges
  
  in Nevada analyzed for bearing loadings including several variations of thermal gradient
  
  loading. One bridge was a two-span concrete posttensioned box girder bridge in Las Vegas,
  
  the second bridge was a two-span composite steel girder bridge in Reno.
  
  Heat flow analysis was conducted using meteorological data from weather stations in
  
  Northern and Southern Nevada to evaluate the AASHTO LRFD thermal gradient
  
  recommended for Nevada. Results showed that AASHTO LRFD Zone 1 thermal gradient
  
  is an unconservative estimate of conditions in the southwestern states for both concrete and
  
  composite superstructures. Analysis in CSiBridge using area models of the concrete bridge
  
  in Las Vegas indicated that the largest predicted thermal gradient obtained through heat
  
  flow analysis increased total exterior bearing loads 12% relative to total load including the
  
  AASHTO thermal gradient. Analysis using area models of the composite steel girder
  
  bridge in Reno indicated that the unaltered temperature profile obtained through heat flow
  
  increased the total exterior bearing 27% relative to total load including the AASHTO
  
  thermal gradient at Abutment 1. Variation of constant temperature through the steel girder
  
  influenced both longitudinal and transverse loading. Reducing the temperature through the
  
  girder maximized bending moment and support reactions, while unaltered temperature
  
  through the girder maximized individual bearing loads. Thus, it is uncertain whether
  
  constant temperature through girder should be included.
• Format:
  PDF
• Funding:
  DTRT13-G-UTC55;P224-14-803/TO #13
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/32588/dot_32588_DS1.pdf
• File Type:
  [PDF - 3.06 MB]
• Collection(s):
  University Transportation Centers ; US Transportation Collection
• Main Document Checksum:
  urn:sha-512:eea3eed6dae7d73b43b0448c1dec407a95c3821dbfb0706c9466b869bb4e84c319f7d36f366fee1fd2bb4d94e4eb84688b5304b22d2a40084c46c068ef23d692