Temperature-insensitive cable tension monitoring during the construction of a cable-stayed bridge with a custom-developed pulse elasto-magnetic instrument

Abstract

Pulse elasto-magnetic method has numerous applications for monitoring cable tension force in cable-stayed bridges. In conventional pulse elasto-magnetic measurements, the feature parameters in frequency domain are seldom discussed. In this study, attempts are made to seek new parameters in frequency domain which are mainly influenced by cable tension force and less sensitive to temperature. A custom-developed pulse elasto-magnetic instrument is employed to conduct cable tension monitoring in the construction stage of a cable-stayed bridge. The field testing results show that only after temperature compensation, the monitoring results of the feature parameters extracted from the magnetic characteristic curve can reflect the stepped changes of cable tension force. Surprisingly, a new frequency-domain parameter, the summation of spectra amplitudes in a carefully selected frequency range, is found to be insensitive to temperature and can well reflect the stepped change behavior of cable tension force. The feasibility of this temperature-insensitive parameter for cable force measurements was verified by field test in two stay cables. The averaged value of the new parameter at each stage linearly depends on cable tension force. The findings about the new frequency-domain parameter may facilitate temperature-insensitive cable tension monitoring in cable-stayed bridge with a pulse elasto-magnetic instrument.