Effectiveness of RWIS Bridge Temperature Simulators

Bridge deck simulators (BDSs), 6 in. (15 cm) concrete cubes with an embedded temperature probe, are intended as a cost-effective substitute for RWIS pavement sensors to represent conditions likely on bridge decks in an area near an RWIS station. In this study, the effectiveness of the BDSs to predict the temperature on nearby bridge decks was evaluated. Nine sites were selected by Ohio Department of Transportation (ODOT) across the state of Ohio (six in northeastern region and three in southwestern region) which were instrumented in BDSs and Nu Metrics pavement sensors on the bridge deck and (with one exception) on the road surface off the bridge. The use of BDSs appears to be unique to Ohio. A survey in the state of Ohio indicated little use was being made of BDS information. RWIS temperature data collected at five minute intervals during winter season 2004-2005 were analyzed and the unusable data were weeded out by removing redundant entries, blank or incomplete entries, extreme temperature readings, and entries where sensor data were not updated. Correlation analysis was performed on the "cleaned" data from the nine sites for the air and BDS temperatures versus bridge deck and road temperatures, and also for air versus BDS temperatures. Separate correlations were made with all-day data and with nighttime data free of solar radiation effects. For both all -day and nighttime data, the BDS was found to better correlate with bridge deck and road temperatures than was the air temperature. The nighttime data were then further analyzed to determine 90%, 95%, 99% prediction limits for the prediction of bridge deck and road temperatures based on the BDS and air temperature values. Again, the prediction limits for bridge and road temperatures using the BDS were generally tighter than when using air temperature. Finite element analyses (FEA) were performed for the nine sites using ALGOR V18 software to investigate the temperature behavior of the bridge deck and the BDS for the air temperature profiles reflecting extreme positive and negative temperature gradients recorded at each site. The FEA modeling provided information about how the BDS and the bridge deck temperature change as a function of the air temperature and time. Larger concrete cube sizes, up to 24 in. (61 cm) on a side, were investigated with FEA in an exporatory manner. The 24 in. (61 cm) cube almost exactly matched the simulated bridge deck temperature profiles under a variety of air temperature loads. The FEA temperature profiles showed that the existing BDS does not always closely represent the true temperature behavior of the bridge deck, but that a concrete cube 4 times larger on a side would compare much better. Yearly training of maintenance personnel in the use of the BDS and RWIS is recommended.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Technical report
  • Features: Appendices; Figures; Maps; Photos; References; Tables;
  • Pagination: 244p

Subject/Index Terms

Filing Info

  • Accession Number: 01054615
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/OH-2007/09
  • Contract Numbers: State Job No. 134216
  • Files: NTL, TRIS, ATRI, USDOT, STATEDOT
  • Created Date: Jul 22 2007 2:26PM