A PORTABLE SELF-MONITORING INSTRUMENT FOR LOAD HISTORY STUDIES

Development and operation of portable instrument for recording strain events in bridges under field service conditions are described. The instrument consists of a transducer, which is clamped to the flange of a bridge by four allen screws, a set of mechanical counters driven by electronic logic circuitry, a battery pack, and a tamper-proof enclosure. As much as eighty days continuous opeation can be realized before batteries must be serviced. Each counter is incremented every time the strain reaches the triggering level selected for that counter. Triggering levels are selected so as to be distributed over a range slightly greater than the strain range expected in the bridge. For the usual case where the triggering levels are all in the elastic range, a simple hand calculation will produce a stress histogram from the counter readings. The theory and a procedure for predicting bridge life from the collected data are also presented. Results of a short field test indicate that the instrument provides a practical and economical means for relatively unskilled personnel to collect stress history data.

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 86 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00139715
  • Record Type: Publication
  • Report/Paper Numbers: Study 74-3
  • Files: TRIS
  • Created Date: Sep 21 1976 12:00AM