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.

Residual tensile force estimation method for earth anchor using elasto-magnetic sensing system

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Nondestructive Testing and Health Monitoring Techniques for Structural Effective Prestress

“…Te value of induced voltage depends on magnetic permeability of the measured object. Te abovementioned double-coil type sensor is also the most widely used one of the ME sensors [65,66,69,73,[75][76][77]80]. However, this type of sensor shows some shortcomings, such as complex design, difcult installation, low signal-to-noise ratio, and slow response [41,71].…”

Comprehensive Indicators for Evaluating and Seeking Elasto-Magnetic Parameters for High-Performance Cable Force Monitoring

“…Detailed operation principles of the charging–discharging circuit can be found in our previously reported results in Ref. [ 18 ]. The charging and discharging process can be switched by controlling the state of two IGBTs (type: IXYX120N120C3, IXYS Corporation, Milpitas, CA, USA) in the circuit.…”

“…The strength of the pulsed magnetic field provided by the excitation coil can be roughly estimated as H ( t )= N 1 U R ( t )/ R s , where N 1 represents the number of coil turns in the primary coil. Digital integration of the voltage signal induced in the secondary coil, U o ( t ), in a magnetization period T can be used to calculate the magnetic induction intensity B ( t ) in the cable [ 18 ]: where N 2 and A m are the turns and cross-sectional area of the secondary coil, respectively; A s is the sectional area of the tested steel cable; μ 0 is the vacuum permeability.…”

“…According to the mechanism of the EM effect, the entire magnetization process of the steel strand/cable is affected by the externally applied tensile force. As a result, plenty of parameters, which are sensitive to the variation in tensile force, can be extracted from the measured EM signals whether it was obtained by a coil or a magnetic sensor [ 18 ]. The calibration results denoting the relationship between the parameters of the EM signal and the cable force highly depend on the used EM sensor and instrument.…”