CN104266857A - Fast bridge load impact coefficient measuring method based on wireless modality technology - Google Patents

Abstract

The invention relates to a fast bridge load impact coefficient measuring method based on the wireless modality technology. Only one time of test needs to be carried out on two test points of a structure, structural modality parameters are recognized according to the analysis results such as the autopower spectrums, the cross-power spectrums, the phase positions and the coherence functions of two response points, the first-order bent modality of a bridge is accordingly determined, and finally the bridge load impact coefficient can be rapidly measured according to the determined first-order bent modality parameters. Cost is low, precision is high, the needed time is short, and the anti-noise capacity is high. Practicality is high, and the fast bridge load impact coefficient measuring method has good prospects that the fast bridge load impact coefficient measuring method can be widely applied to fast measurement of the bridge load impact coefficient in the actual project.

Description

Based on the bridge load coefficient of impact method for fast measuring of wireless modalities technology

Technical field

The present invention relates to a kind of recognition methods of modal parameter of Railway Bridge Dynamic Test technology, especially a kind of bridge load coefficient of impact method for fast measuring based on wireless modalities technology.

Background technology

In bridge experiment, can evaluate the train operation performance of bridge structure according to the measured value of coefficient of impact, actual measurement coefficient of impact greatly then illustrates that the train operation performance of bridge structure is poor, and the smooth degree of bridge floor is bad, and vice versa.If Bridge Impact Coefficient can not be measured quickly and accurately, the bridge collapse phenomenon that carload causes may be caused, time serious, also major accident may occur, cause imponderable heavy losses.Utilize dynamic vibration test data to identify bridge structure parameter, not only can obtain bridge modal parameter, realize the Quick Measurement to bridge load coefficient of impact, and can effectively avoid bridge collapse accident, ensure the person and national wealth safety.But, in the modal parameters test of tradition Bridge Impact Coefficient, require sensor to be arranged in whole bridge floor, required number of sensors is many, data cable long, the required manpower and materials of equipment installation are large, the bridge shut-in time is long, and the data subsequent analysis processing time is long.

Summary of the invention

The technical problem to be solved in the present invention is: propose a kind of bridge load coefficient of impact method for fast measuring based on wireless modalities technology, can realize the Quick Measurement to bridge load coefficient efficiently, thus effectively avoid bridge security accident.

The technical solution adopted in the present invention is: a kind of bridge load coefficient of impact method for fast measuring based on wireless modalities technology, comprises the following steps:

1) utilize physical environment energisation mode, place two bridge mould measurement modules at the not a node positional symmetry of bridge single order mode of flexural vibration and determine two measuring points, and the time-domain signal collection of measuring point response is carried out to two measuring points; Two bridge mould measurement module symmetry are placed on bridge floor center and along bridge deck width direction.

2) time-domain signal collected is carried out Fourier function F FT to convert, obtain the auto-power spectrum of two measuring points, cross-power spectrum, phase place and coherence function;

3) according to the peak value of the curve of auto-power spectrum, cross-power spectrum, phase place and coherence function determination single order model frequency; If two measuring point phase differential are close to 0 °, then represent that two spot moving directions are consistent, this Mode Shape is that single order bends the vibration shape; If two measuring point phase differential are close to 180 °, then represent that two spot moving directions are contrary, this Mode Shape is single order torsion vibration mode;

4) according to step 3) in the single order mode of flexural vibration natural frequency of bridge structure determined, calculate coefficient of impact μ:

As f<1.5Hz, μ=0.05;

As 1.5Hz≤f≤14Hz, μ=0.1767ln f-0.0157;

As f>14Hz, μ=0.45;

In formula, f is structure fundamental frequency, and unit is hertz Hz, i.e. single order mode of flexural vibration natural frequency.

The inventive method only once need be tested structure two measuring points, can greatly reduce bridge dynamic characteristic measuring cost and time on the one hand, adopt bridge wireless mould measurement module on the other hand, the built-in high sensitivity of module, low-frequency velocity sensor, perfect signal fits tune, voltage amplification, anti-aliasing filtering, data acquisition hardware system, built-in high-performance lithium electric battery, it has, and anti-noise ability is strong, wirelessly transmitting data, the feature such as practical.

The invention has the beneficial effects as follows: only once need test structure two measuring points, modal parameters is identified again by the auto-power spectrum of two response point, cross-power spectrum, the analysis result such as phase place and coherence function, and determine the single order mode of flexural vibration of bridge thus, realize the Quick Measurement to bridge load coefficient of impact finally by the single order mode of flexural vibration parameter determined; Not only cost is low, precision is high, required time is few, anti-noise ability is strong; And practical, be widely used in the good prospect of Practical Project Bridge coefficient of impact Quick Measurement.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the present invention is further described.

Fig. 1 is schematic flow sheet of the present invention;

Fig. 2 is bridge measuring point schematic diagram;

Fig. 3 is bridge vertical single order mode of flexural vibration vibration shape schematic diagram;

Fig. 4,5 be bridge two measuring point from spectrogram;

Fig. 6 is cross-spectrum and the phase diagram of bridge two measuring point;

Fig. 7 is the coherence function figure of bridge two measuring point.

Embodiment

The present invention is further detailed explanation with preferred embodiment by reference to the accompanying drawings now.These accompanying drawings are the schematic diagram of simplification, only basic structure of the present invention are described in a schematic way, and therefore it only shows the formation relevant with the present invention.

As shown in the flowchart of fig.1, based on the bridge load coefficient of impact method for fast measuring of wireless modalities technology, comprise the following steps:

1) utilize physical environment energisation mode, two DH5907N wireless modalities test modules are installed on left and right sides measuring point in the middle part of bridge; And two measuring points are carried out to the time-domain signal collection of measuring point response;

Mounting points as shown in Figure 2; Wherein, DH5907N wireless modalities test module is selected from the wireless modalities test module that Jiangsu Dong Hua measuring technology incorporated company produces.

2) time domain data recorded by DH5907N wireless modalities test module to computing machine, then calculates the auto-power spectrum, cross-power spectrum, cross-spectrum phase and the coherence function that time domain data are converted into these two time-domain signals by wireless transmission by dynamic signal acquisition analytic system; As shown in figs. 4-7.

Wherein, dynamic signal acquisition analytic system adopts the DHDAS dynamic signal acquisition analytic system that Jiangsu Dong Hua measuring technology incorporated company produces.

3) according to the peak value of the curve of auto-power spectrum, cross-power spectrum, phase place and coherence function determination single order model frequency; As shown in Figure 3;

If two measuring point phase differential are close to 0 °, then represent that two spot moving directions are consistent, this Mode Shape is that single order bends the vibration shape; If two measuring point phase differential are close to 180 °, then represent that two spot moving directions are contrary, this Mode Shape is single order torsion vibration mode;

4) when after the single order mode of flexural vibration natural frequency determining bridge structure, coefficient of impact μ is calculated:

As f<1.5Hz, μ=0.05;

As 1.5Hz≤f≤14Hz, μ=0.1767ln f-0.0157;

As f>14Hz, μ=0.45;

In formula, f is structure fundamental frequency, and unit is hertz Hz, i.e. single order mode of flexural vibration natural frequency.

The just the specific embodiment of the present invention described in above instructions, various illustrating is not construed as limiting flesh and blood of the present invention, person of an ordinary skill in the technical field after having read instructions can to before described embodiment make an amendment or be out of shape, and do not deviate from the spirit and scope of the invention.

Claims (4)

1., based on a bridge load coefficient of impact method for fast measuring for wireless modalities technology, it is characterized in that comprising the following steps:

1) utilize physical environment energisation mode, place two bridge mould measurement modules at the not a node positional symmetry of bridge single order mode of flexural vibration and determine two measuring points, and the time-domain signal collection of measuring point response is carried out to two measuring points;

2) time-domain signal collected is carried out Fourier function F FT to convert, obtain the auto-power spectrum of two measuring points, cross-power spectrum, phase place and coherence function;

3) according to the peak value of the curve of auto-power spectrum, cross-power spectrum, phase place and coherence function determination single order model frequency;

4) according to step 3) in the single order mode of flexural vibration natural frequency of bridge structure determined, calculate coefficient of impact μ.

2., as claimed in claim 1 based on the bridge load coefficient of impact method for fast measuring of wireless modalities technology, it is characterized in that: described step 1) in, two bridge mould measurement module symmetry are placed on bridge floor center and along bridge deck width direction.

3. as claimed in claim 1 based on the bridge load coefficient of impact method for fast measuring of wireless modalities technology, it is characterized in that: described step 3) in, if two measuring point phase differential are close to 0 °, then represent that two spot moving directions are consistent, this Mode Shape is that single order bends the vibration shape;

If two measuring point phase differential are close to 180 °, then represent that two spot moving directions are contrary, this Mode Shape is single order torsion vibration mode.

4., as claimed in claim 1 based on the bridge load coefficient of impact method for fast measuring of wireless modalities technology, it is characterized in that: described step 4) in, the account form of coefficient of impact μ is:

As f<1.5Hz, μ=0.05;

As 1.5Hz≤f≤14Hz, μ=0.1767lnf-0.0157;

As f>14Hz, μ=0.45;

In formula, f is structure fundamental frequency, and unit is hertz Hz, i.e. single order mode of flexural vibration natural frequency.