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
• Abstract:
  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.
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• 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