Validation of Coaxial Cable Sensors for Dynamic Crack Detection in RC Columns Under Blast Loads

This study is aimed at validating the sensitivity and resolution of topology-based cable sensors with field testing of three columns, conducting the proof-of-concept tests of an Electrical Time-Domain Reflectometry (ETDR) measurement instrument for real-time detection of the location and time of cracks under cyclic loading, and detecting cracks in RC columns and correlating crack measurements with the strain values on nearby reinforcing bars. To achieve the project objectives, three columns were tested under blast loads: one control specimen and two retrofitted specimens. One cable sensor was installed on the rear (tension) face of each column prior to any strengthening. Proof-of concept blast tests indicated that the sensor and ETDR measurement instrument used during the tests shows the overall distribution of cracks and the location of plastic hinges. The sensitivity of the sensors for crack detection is high in comparison with the noise level. However, the local peaks were not observed for individual cracks due to the limited spatial resolution associated with the measurement instrument used during the blast tests. In the plastic hinge area, the time history of crack opening and closing corresponds well with the strain change measured from the nearby steel reinforcing bar. The large cracks observed during the blast were also seen after the blast was over, indicating the “memory” feature as observed from slowly loaded columns.

Language

  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References;
  • Pagination: 40p

Subject/Index Terms

Filing Info

  • Accession Number: 01108448
  • Record Type: Publication
  • Report/Paper Numbers: NUTC R207, Report No. 00017865
  • Contract Numbers: DTRT06-G-0014
  • Files: UTC, TRIS, USDOT
  • Created Date: Aug 13 2008 1:06PM