JP3574850B2 - Axle load measurement method for vehicles running on bridges - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for measuring an axle load of a vehicle based on a moving load applied to the bridge by the vehicle when the vehicle runs on the bridge.
[0002]
[Prior art]
Measuring the weight of a vehicle traveling on a bridge is important in maintaining the bridge. As such a weight measuring method, for example, a sensor is installed on a road surface, a method of measuring the weight of a vehicle traveling on the sensor, or a method of measuring a bending moment generated on a bridge girder by running of the vehicle, and applying the measured value to the measured value. Conventionally, a method of determining the weight of a vehicle based on such information has been proposed.
[0003]
However, in the former case, there is a problem that the sensor is easily worn out, and maintenance work of the sensor on a bridge with heavy traffic needs to be performed after ensuring the safety of workers sufficiently due to traffic regulations. In such cases, there are problems that data processing and adjustment of the measurement system are complicated, and that accurate measurement of the number of axles and axle weight is difficult even if the total weight of the vehicle can be measured.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems, to facilitate installation and maintenance of a measuring means such as a sensor, and to easily perform data processing and adjustment of a measuring system. To provide a method for measuring axle load.
[0005]
[Means for Solving the Problems]
That is, the method of measuring the axle load of a vehicle traveling on a bridge according to the present invention is as follows.
When measuring the axle load of a vehicle traveling on a bridge,
The axle load of the vehicle is determined based on the amount of change in the fulcrum reaction force with respect to the moving load at a location where the shape of the line of influence of the fulcrum reaction force of the bridge girder with respect to the moving load of the bridge with respect to the moving load of the vehicle changes suddenly. It is a feature that is required.
[0006]
The method for measuring the axle load of a vehicle traveling on a bridge according to the present invention includes:
The type and running speed of the vehicle are obtained based on the amount of change in the fulcrum reaction force of the bridge girder .
[0007]
【The invention's effect】
In the method of measuring the axle load of a vehicle traveling on a bridge according to the present invention, when the vehicle travels on the bridge, paying attention to an influence line that is a function of a response value of a bridge member to a moving load applied to the bridge by the vehicle, At the point where the shape of the influence line changes in the load, that is, where the vehicle suddenly changes with the traveling of the vehicle, the amount of change in the response value to the moving load, for example, the amount of change in the strain is detected. The weight is to be measured.
[0008]
The response value (for example, strain) to the moving load at the measurement location is affected by each axle load when the axle load (that is, the moving load) of each axle of the vehicle reaches the bridge with a time difference. When a moving load due to one axle of a vehicle passes through a point where the shape of the influence line, which is a function of the response value of the bridge member to the axle load, suddenly changes, the waveform of the response value to the moving load there also occurs. On the other hand, since the other axles are located in places other than where the shape of the influence line changes suddenly, the amount of change in the waveform of the response value in a short time interval is mainly due to the load (axle load) due to the axle passing through the measurement point. ). The present invention measures the axle based on this.
[0009]
Therefore, it is sufficient to select only the location where the influence line changes suddenly as the measurement location, so that the number of measurement locations can be reduced, and it is not necessary to install sensors for measurement on the road surface. In addition, the sensor is not worn out in a short period of time, so that the measurement can be performed for a long time at a low cost, and the safety of a worker at the time of installing and maintaining the sensor can be ensured.
[0010]
In addition, since the amount of change in the response value (for example, strain) with respect to the moving load is measured, it is possible to obtain the axial load with high accuracy by a relatively simple data processing procedure.
[0011]
Furthermore, since the measurement location, that is, the location where the shape of the influence line changes abruptly, can be obtained relatively easily by calculation from the design drawing of the bridge to be measured in advance, the measurement location should be set easily and efficiently. Is possible.
[0012]
In particular, in the method of measuring the axle load of a vehicle traveling on a bridge according to the present invention, the fulcrum reaction force of a bridge girder is used as a response value to a moving load, and the axle load is calculated based on a variation amount of the fulcrum reaction force accompanying the passage of the vehicle. You are seeking.
[0013]
As a result, the abutment of the bridge or the fulcrum on the pier can be used as a measurement point, and the number of places where sensors (for example, strain gauges) for measurement are installed can be greatly reduced. Since the sensor does not need to be installed in a short time, the sensor does not wear out in a short period of time, making it possible to perform long-term measurement at a low cost and ensure the safety of workers when installing and maintaining the sensor. You can also. Further, it is also possible to determine the type of the vehicle and determine the traveling speed from the amount of change in the fulcrum reaction force accompanying the passage of the vehicle.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0015]
1 and 2 show an embodiment of the present invention. FIG. 1 is a view along a bridge axis direction of a bridge for which axle load is measured, and FIG. 2 is a view along a width direction. In the bridge 1 for measuring the axle load of a vehicle, a floor slab 7 as a road surface is installed on a girder web 6 bridged between abutments 2 and 3 via bearings 4 and 5, and a vehicle 8 is mounted on the floor slab 7. Is a simple girder plate girder bridge that runs. As shown in FIG. 2, the bridge 1 is an upper and lower two-lane type bridge supporting a floor slab 7 with four girder webs 6, and each girder web 6 is provided with a vertical stiffener 9 and Between the girder webs 4, a plurality of cross girder 10 are bridged, and diagonal reinforcing members 11, 12 are also provided.
[0016]
In the present embodiment, the measurement of the axle load of the vehicle on the bridge 1 is determined from the fulcrum reaction force of the bridge 1. Here, the fulcrum reaction force on the abutment 3 is measured using the strain gauge 13. FIG. 3 and FIG. 4 show the locations where strain gauges are attached in detail. The strain gauge 13 is attached to a vertical stiffener 9 provided on a girder web 6 installed on the abutment 3 via a bearing 5.
[0017]
The strain gauge 13 attached to the vertical stiffener 9 is connected to a dynamic strain meter (not shown) to measure the time history waveform of the strain. That is, a strain due to the fulcrum reaction force is generated in the vertical stiffener 9 with the passage of the vehicle, in this case, a compression strain proportional to the fulcrum reaction force is generated. Therefore, the change in the compression strain is measured to determine the fulcrum reaction force. be able to. Further, by obtaining the time history waveform, it is possible to obtain a change in the fulcrum reaction force accompanying the passage of the vehicle.
[0018]
FIG. 5 is a graph showing the temporal change of the influence line of the fulcrum reaction force due to the movement of the load on the simple girder, that is, the shape of the influence line. The horizontal axis represents the distance from the origin of the simple girder, and the vertical axis represents the distance. Indicates the value of the influence line. Here, the origin of the simple girder is one end on the side where the load enters, and the fulcrum reaction force indicates a value at the other end. The value of the influence line shown on the vertical axis is dimensionless with -1 being the maximum value.
[0019]
As is clear from the figure, the value of the influence line is maximum at the fulcrum of interest and is 0 at the other fulcrum. Also, it can be seen that the shape of the influence line is also rapidly changing from the maximum value to the minimum value at the fulcrum of interest. This is because the load applied to the girder suddenly disappears when the load moving on the girder withdraws from the girder, and the fulcrum reaction force also disappears at the same time. This indicates that the fulcrum of interest is a point where the shape of the influence line of the fulcrum reaction force changes abruptly.
[0020]
Next, an experiment performed to verify the axle load measurement method according to the present invention and the results thereof will be described.
[0021]
FIG. 6 shows a vehicle model used for measuring the axle load of a vehicle traveling on a bridge for verification of the axle load measurement method according to the present invention. The vehicle 20 used as a model is a six-wheel truck, in which the front wheels (first shaft 20a) have an axle load of 5 tonf and the rear wheels (the second shaft 20b and the third axle 20c) have an axle load of 10 tonf. The axle load is measured by measuring the change in the fulcrum reaction force when the vehicle 20 enters the bridge 1 shown in FIG. 1 from the left side (the abutment 2 side), travels on the bridge 1 and exits the right side (the abutment 3 side). , Determined from the variation in strain detected by the strain gauge 13 provided at the measurement location (see FIGS. 1 to 4).
[0022]
FIG. 7 is a graph showing the temporal change (time history waveform) of the strain at the measurement point (see FIGS. 1 to 4), in which the horizontal axis represents time and the vertical axis represents strain (strain gauge value). From the figure, it can be seen that when each axle of the vehicle 20 passes through the measurement point, that is, on the fulcrum, the value of the strain as the response value changes rapidly. This indicates that, as described above, the load suddenly disappears when each axle passes over the fulcrum, so that the fulcrum reaction force caused by the load also suddenly disappears, and this is detected by the strain gauge 13. ing.
[0023]
Next, in order to perform the sudden change of the distortion more accurately, the forward difference was calculated for the time history waveform of FIG. 7 to obtain a difference waveform. FIG. 8 shows this differential waveform, in which the horizontal axis represents time, and the vertical axis represents the load converted from the strain value.
[0024]
When the difference waveform is obtained by performing forward difference calculation on the time history waveform, a peak occurs in the difference waveform where the original waveform changes suddenly, and the difference amount becomes extremely small in other portions. Therefore, the time at which this peak occurs indicates the load, that is, the time at which the vehicle passed the axle, and the axle load can be obtained by converting the strain at this time. The axle load is defined assuming that the sum of the area of the vertical stiffener to which the strain gauge is attached and the area of the girder web immediately above the bearing is A, the strain is ε, and the Young's modulus of the girder web is E, the fulcrum reaction force (load) P is , And the following equation
P = A × E × ε
Can be obtained by
[0025]
From FIG. 8, the obtained axle weight is 2.5 tonf on the first axis, and 5 tonf on each of the second and third axes. This is half the actual axle load of the vehicle shown in FIG. 6, but as shown in FIG. 2, the bridge 1 has a structure in which the road surface for two lanes is supported by four girder webs 4, This is because one lane is supported by two girder webs 4, that is, the axle weight of the vehicle is equally applied to the two girder webs 4.
[0026]
In the above measurement, the response value (fulcrum reaction force) to the vehicle traveling on the up lane of the bridge 1 is obtained. However, actually, the fulcrum reaction force is also generated by the vehicle traveling on the down lane. However, the fulcrum reaction force generated at the fulcrum on the up lane side due to the load from the vehicle traveling on the down lane is due to the lateral load distribution on the bridge 1, and there are cases where a load is directly applied to the girder web on the up lane side. Has a different shape of the line of influence of the fulcrum reaction force. The fulcrum reaction force due to this load distribution is transmitted, for example, by the cross beam 10 and the diagonal reinforcing members 11 and 12 (see FIG. 2), and the shape of the influence line due thereto is different from that shown in FIG. Usually, there is no sudden change.
[0027]
Therefore, the time history waveform of the strain gauge 13 is measured for a certain period of time while the vehicle is passing, a difference waveform of the obtained time history waveform is obtained, the passing time of a specific vehicle is detected from the peak, and the distortion time at that time is detected. The axle load of the vehicle can be obtained from the variation.
[0028]
In addition, the type of the vehicle can be determined and the traveling speed can be obtained from the interval of the peak waveform occurrence time. In this case, for example, a TV camera is installed on the bridge or in the vicinity thereof, and it is possible to identify the vehicle by comparing the time at which the vehicle passes with the time at which the strain occurs, and strain gauges are provided at the fulcrums at both ends of the girder web. Install, determine the difference waveform of the strain due to the passage of one vehicle, determine the difference between the peak occurrence time by comparing the two, and determine the passing speed of the vehicle by dividing the distance between the fulcrum by this occurrence time difference It is also possible.
[0029]
Furthermore, since it is possible to obtain the peak of the axle load by a specific vehicle by obtaining the difference between the time history waveforms of the strains, even when a plurality of vehicles are traveling in the same lane or adjacent lanes at the same time. Axial load measurement is possible.
[0030]
As described above, the method for measuring the axle load of a vehicle traveling on a bridge according to the present invention can easily and accurately obtain the axle load of a vehicle with relatively simple equipment and measuring procedures.
[0031]
In particular, the number of measurement points can be reduced, and it is not necessary to install a sensor or the like for measurement on the road surface. Therefore, the sensor is not worn out in a short period of time, and has a low cost for a long period of time. Measurement can be performed, and the safety of workers during installation and maintenance of the sensor can be ensured.
[0032]
Note that the present invention is not limited to the embodiment described above. In the above-described embodiment, the fulcrum reaction force is set as a measurement target. However, another response value of a bridge member that fluctuates with movement of a vehicle, for example, a bending moment or the like can be selected as a measurement target.
[Brief description of the drawings]
FIG. 1 is a view along a bridge axis direction of a bridge for measuring axle load of a vehicle according to an embodiment of the present invention.
FIG. 2 is a view along the width direction of the bridge of FIG. 1;
3A and 3B are views showing in detail a strain gauge mounting position in the bridge of FIG. 1, wherein FIG. 3A is a view in a bridge axis direction and FIG. 3B is a view in a width direction.
FIG. 4 is a top view of a strain gauge mounting position in the bridge of FIG. 1;
FIG. 5 is a diagram showing an influence line of a fulcrum reaction force when a load moves on a simple girder.
FIG. 6 is a diagram schematically illustrating a vehicle model for performing axle load measurement according to the present invention.
FIG. 7 is a graph showing a time change of a strain caused by a fulcrum reaction force generated at the fulcrum when the vehicle shown in FIG. 6 travels on the bridge of FIG. 1;
FIG. 8 is a diagram showing an axial load obtained by calculating a difference between the waveforms of FIG. 7;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bridge 2, 3 Abutment 4, 5 Bearing 6 Girder web 7 Floor slab 8 Vehicle 9 Vertical stiffener 10 Horizontal girder 11, 12 Diagonal reinforcement 13 Strain gauge 20 Vehicle model

Claims (2)

When measuring the axle load of a vehicle traveling on a bridge,
The axle load of the vehicle is determined based on the amount of change in the fulcrum reaction force with respect to the moving load at a location where the shape of the line of influence of the fulcrum reaction force of the bridge girder with respect to the moving load of the bridge with respect to the moving load of the vehicle changes suddenly. A method for measuring the axle load of a vehicle traveling on a bridge, the method being characterized in that: The method of claim 1, wherein
A method of measuring the axle load of a vehicle traveling on a bridge, wherein a type and a traveling speed of the vehicle are obtained based on a variation amount of a fulcrum reaction force of the bridge girder.

Images