Measuring method of strain dynamic coefficient

Abstract

The invention discloses a measuring method of the strain dynamic coefficient. The measuring method comprises the following steps that step (10): dynamic strain sample collection is carried out, wherein a grating strain meter is matched to a strain acquisition system, then the grating strain meter acquires dynamic strain of a measuring point, and a dynamic strain sample is formed; step (20): the FIR Kaiser window filter parameters are designed, an ideal filter mode is set to be the ideal low pass filtering mode, and the cut-off frequency, the transition band and the ripple of the FIR Kaiser window filter are determined; step (30): the FIR Kaiser window filter is generated, and the dynamic strain sample is filtered; step (40): the dynamic coefficient of the structure local strain is measured. The measuring method can accurately measure the dynamic coefficient of the structure local strain.

Description

technical field [0001] The invention relates to a method for measuring the dynamic coefficient of strain, in particular to a method for determining the local dynamic coefficient of a structure based on a measured dynamic strain sample. Background technique [0002] In the process of design, maintenance, safety assessment and reinforcement of bridge structures, the so-called "dynamic coefficient" is usually used to characterize the intensity of bridge structure vibration under the action of trains. It is defined as the ratio of the dynamic response (dynamic deflection or stress) to the static response (static deflection or stress) produced by train operation to the structure. If the dynamic coefficient is not used properly, it will greatly affect the economic indicators of bridge construction and maintenance. The dynamic coefficient is generally derived from the overall dynamic response of the main structure of the bridge under the load of the train, while the local vibratio...

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Problems solved by technology

[0003] At present, in various civil engineering and construction fields, there are several methods for determining the dynamic strain coefficient based on dynamic strain collection samples: (1) Empirical identification method: based on the collected dynamic strain samples, the static strain time history of the local position of the structure is determined empirically , the kinetic coefficient is determined by dividing the dynamic strain peak value of the collected sample by the static strain peak value obtained from experience. This method requires practitioners to have rich experience and knowledge, and the accuracy is poor; (2) Theoretical calculation and assumption method: this method It is necessary to establish a mechanical calculation model or a finite element calculation model of the bridge structure in advance, and calculate the local static strain time history of the structure under the same load as the collected sample, and finally divide the dynamic strain peak value of the collected sample by the calculated static strain peak value to determine Dynamic coefficient, this method depends on the accuracy of the calculation model, and the feasibility is poor; (3) wavelet packet decomposition method: this method performs wavelet packet decomposition on the collected dynamic strain samples, and selects the low frequency components in the wavelet packet as the static strain Time history curve, the kinetic coefficient is determined by dividing the dynamic strain peak value of the collected sample by the static strain peak value obtained by the low-frequency component decomposed by the wavelet packet. This method requires practitioners to have rich knowledge of wavelet packet and signal processing. It is suitable for Therefore, it is necessary to study a new method with good feasibility, high accuracy and strong applicability for the determination of the local dynamic coefficient of the structure based on the sample collected by dynamic strain

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