Experimental verification of the influence of time-dependent material properties on long-term bridge characteristics.

Details

• Creators:
  Lewis, Michael ; Karbhari, Vistasp M.
• Corporate Creators:
  University of California, San Diego. Dept. of Structural Engineering
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  Concrete Bridges Maintenance And Repair Post-tensioned Prestressed Concrete Construction
• Publication/ Report Number:
  FHWA/CA/ES-2006/24 ; UCSD / SSRP-06/20
• Resource Type:
  Tech Report
• Geographical Coverage:
  California
• Corporate Publisher:
  California. Department of Transportation
• Abstract:
  Post-tensioned cast-in-place box girder bridges are commonly used in California. Losses in tension in
  
  the steel prestressing tendons used in these bridges occur over time due to creep and shrinkage of
  
  concrete and relaxation of the tendons. The use of existing methods in bridge specifications used to
  
  predict these long-term losses often result in inaccurate estimate of losses leading to severe
  
  serviceability problems. The current research program aims at developing a more precise method for
  
  predicting the long-term prestress loss in concrete bridges. Two spans in a recently constructed posttensioned
  
  concrete bridge were instrumented with vibrating wire strain gages to monitor the longterm
  
  deformations and determine prestress loss. The recorded measurements of prestress loss were
  
  compared with the available equations from several bridge specifications as well as with analytical
  
  models developed for long-term deformations of concrete structures. To ensure accuracy in the
  
  values of the input material parameters, creep and shrinkage of concrete were simultaneously
  
  determined experimentally. This research has shown that shrinkage is highly dependent on
  
  environmental influences. Additionally, measured creep and shrinkage appeared to reach asymptotes
  
  faster than was indicated by best-fit equations, thus ultimate values may be closer to the minimum
  
  extrapolated values. It is noted that the available specifications equations for predicting prestress loss
  
  may not be sufficiently accurate. The analytical predictions of prestress loss exceed the monitored
  
  values in some cases and further investigation is being continued and will be reported in the final
  
  report for this project.
  
  
• Format:
  PDF
• Funding:
  59A0420
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:d3b5d3ddba29c483824f3cb8451b98fc45926a3839497d38a4a2a977744677c7
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/27526/dot_27526_DS1.pdf
• File Type:
  [PDF - 4.67 MB ]