Precast concrete I-girders are commonly used by the Florida DOT to support short to moderately spanned highway bridges. These girders are subjected to daily and seasonal temperature variation during storage at precast yards. Thermal gradient over the depth of such girders can cause unwanted effects such as cracking, twisting or camber. This study was undertaken to investigate the temperature gradients and strains caused by differential temperature on precast girders. Types II, IV, V and VI AASHTO girders were instrumented with thermocouples and vibrating wire strain gages at a precast yard in two phases. Dataloggers were used to collect and store data over two week periods in summer and winter. Temperature and strain data were normalized with respect to the initial data. Data distributions over the depth and length of precast girders were developed. These distributions were compared with theoretical distributions from a computer program. It was found that the heat of hydration released soon after concrete casting in precast girders was significant during the first 24 hours. The temperature increase due to this effect can be as much as 48 deg F. Subsequently, the temperatures stabilize and undergo daily maximums (3 pm to 4 pm) and minimums (6 am to 7 am). The daily temperature range may near 30 deg F, while the daily peak may be near 100 deg F. It was found that the surface area of precast girders plays an important role in determining the radiational heat lost from these girders. In general, more heat is retained in the flanges of precast girders than the webs. Also, it was noted that the temperature remains essentially constant over girder length. Hypothetical thermal expansion coefficients developed for type VI girders varied over a wide range. This proves that a constant thermal coefficient should not be used to predict thermal strains in precast girders.

  • Corporate Authors:

    Florida State University, Tallahassee

    Department of Civil Engineering, 2525 Pottsdamer Street
    Tallahassee, FL  United States  32310

    Florida Department of Transportation

    Haydon Burns Building, 605 Suwanee Street
    Tallahassee, FL  United States  32301

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Yazdani, N
  • Publication Date: 1992-7


  • English

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 132 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00625453
  • Record Type: Publication
  • Report/Paper Numbers: FL/DOT/RMC/0583-3556, WPI No. 0510583
  • Created Date: Dec 4 1996 12:00AM