JP6467304B2 - Bridge dynamic response evaluation method - Google Patents

Description

  The present invention relates to a method for evaluating a dynamic response of a railway bridge, and more particularly to a method for determining an impact coefficient (dynamic response component) of a bridge using a vehicle vertical acceleration response of a traveling train when passing through the bridge.

  In railway bridges such as high-speed railway bridges and viaducts, as shown in FIG. 7, resonance may occur due to periodic excitation caused by the regular axle arrangement of the traveling train, and a large dynamic response may occur. .

Such a large dynamic response generated during train travel has been reflected in the design as an impact coefficient.
On the other hand, the train travel speed has increased dramatically, and the PRC structure (prestressed concrete structure) has been adopted for the majority of railway bridges, and low rigidity girders have become popular. As for the designed structures, there are many cases where the formulas used in the design are not applied, and on-site measurements have confirmed that the resonance of the bridge during running of the train is higher than before. It has been confirmed that a large response is excited by resonance even at a traveling speed of 200 km / h due to the reduction in rigidity of the girders.

  In addition, because high-speed railway bridges have a deflection limit during train travel, if dynamic response components are greatly excited by resonance during train travel, this is an important index for evaluating the dynamic response. The impact coefficient is used as Furthermore, the impact coefficient is also an important indicator in maintenance management because it is closely related to deterioration phenomena such as cracks in railway bridges.

  Conventionally, when evaluating the impact coefficient of a railway bridge, a ring displacement meter, video measurement, U Doppler (non-contact vibration measurement system for structures with a built-in laser Doppler velocimeter), etc. are used. The vertical displacement of the bridge is measured on the bridge side (ground side) (deflection measurement), and the impact coefficient is obtained using this measurement result (see, for example, Patent Document 1).

JP 2012-233758 A

  However, in the conventional bridge dynamic response evaluation method described above, it is necessary to perform one deflection measurement on each bridge side (on the ground side) for each bridge. At that time, even if the structure of the railroad bridge is the same, the structural performance (degree of deterioration, etc.) may vary greatly due to the construction and shared environment. Although it is desirable to implement it on all railway bridges, it is extremely laborious and difficult to implement on all railway bridges on long lines.

  Even if it is implemented for a typical railway bridge, there are cases where deflection measurement itself cannot be performed when it is built on national roads, railways, rivers, etc., or at places where wind is always strong. .

  In view of the above circumstances, the present invention pays attention to the vehicle acceleration response of a train traveling on a bridge, and by using an index based on the vertical acceleration response of the vehicle, the impact coefficient of the bridge is obtained without performing a deflection measurement work. It is an object of the present invention to provide a bridge dynamic response evaluation method that enables dynamic response evaluation / bridge soundness evaluation.

  In order to achieve the above object, the present invention provides the following means.

According to the bridge dynamic response evaluation method of the present invention, an accelerometer that measures vertical acceleration is provided in each of the leading and trailing vehicles of a train, and the vehicle acceleration that measures the vertical acceleration of the leading and trailing vehicles during travel is provided. Measurement of the acceleration data at the time of passing through the bridge and the acceleration data extraction process at the time of passing through the bridge to extract the measurement data of the accelerometer at the time of passing through the bridge. the acceleration amplification factor calculation step by dividing the feature value of the vertical acceleration and calculates the acceleration amplification factor, previously determined Tei was duty bridge by applying said acceleration amplification factor relationship of duty and acceleration amplification factor of bridges And an impact coefficient calculating step for calculating.

  In the bridge dynamic response evaluation method according to the present invention, it is desirable that the vertical acceleration feature amount is at least one of a maximum value, a minimum value, and an RMS of an acceleration waveform when passing through the bridge.

  In the bridge dynamic response evaluation method of the present invention, the impact coefficient of the bridge can be obtained and evaluated simply and comprehensively from the response of the vehicle of the traveling train. That is, the impact coefficient of a huge number of bridges constituting a route can be easily grasped without measuring the deflection of each bridge.

  In addition, since the impact coefficient of the bridge can be easily and comprehensively determined from the response of the train train, it is possible to determine the bridge constructed on national roads, railways, rivers, etc. The impact coefficient can be obtained even for bridges where it is difficult to perform deflection measurement.

  Furthermore, when the train travels on a daily basis, it is also possible to track the change in impact coefficient with time.

  Therefore, according to the bridge dynamic response evaluation method of the present invention, extraction of weak points based on actual structural performance and selection of detailed measurement points become much easier, and investigation and management can be made more efficient. become.

It is a figure which shows the relationship between bridge deflection and the head vehicle acceleration / tail vehicle acceleration. It is a figure which shows the bridge dynamic response evaluation method which concerns on one Embodiment of this invention, and is a flowchart which shows the impact coefficient estimation method of a bridge using the acceleration of a traveling vehicle. It is a figure which shows an example of the relationship between the acceleration amplitude rate and impact coefficient in a bridge with span length of 25 m. It is a figure which shows the estimation precision of the estimation formula (2) based on an acceleration amplitude rate. It is a figure which shows an example of the relationship between the acceleration amplitude rate and impact coefficient in a bridge with span length of 45 m. It is a figure which shows the estimation precision of the estimation formula (3) based on an acceleration amplitude rate. It is a figure which shows an example of the resonance waveform of the railway bridge at the time of train travel.

  Hereinafter, a bridge dynamic response evaluation method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6.

  First, in a railway bridge, as shown in FIG. 1, the greater the deflection of the bridge, the greater the acceleration of the vehicle. In addition, there is almost no dynamic response on the bridge when the train passes the top vehicle (only static response).

  In the bridge dynamic response evaluation method of this embodiment, paying attention to the characteristics of the above-mentioned railway bridge, as shown in FIG. 1 and FIG. 1, the first carriage 1c or the second carriage of the first vehicle 1a and the last vehicle 1b of the train 1 is used. The accelerometer 2 is provided on 1d, and the acceleration in the vertical direction when the leading vehicle 1a and the last vehicle 1b travel on the train is measured (vehicle acceleration measuring step). In addition, the traveling speed of the train is measured at any time.

  Note that the accelerometer 2 is not necessarily limited to being provided on the first carriage 1c or the second carriage 1d of each vehicle 1a, 1b. That is, the accelerometer 2 may be installed by selecting an arbitrary position so as to reduce errors caused by measurement points and vehicle vibration as much as possible.

  Then, as shown in FIG. 2, in the bridge dynamic response evaluation method of the present embodiment, based on the bridge data storing the traveling speed of the train 1, the span length, the starting kilometer, the terminal kilometer, and the design impact coefficient, The measurement data of the accelerometer 2 when the train 1 is passing through the target bridge is extracted (acceleration data extraction process when passing through the bridge).

Further, the feature amount is calculated from the vertical acceleration of the first and last vehicles 1a and 1b passing through the target bridge (the acceleration feature value calculation step of the first / last vehicle).
Here, examples of the feature amount of the vertical acceleration of each vehicle 1a, 1b include the maximum value, the minimum value, and RMS (average amplitude) of the acceleration waveform when passing through the bridge.

Next, as shown in the following equation (1), a value obtained by dividing the feature quantity of the vertical acceleration waveform measured by the last vehicle 1b by the feature quantity of the vertical acceleration measured by the leading vehicle 1a (acceleration amplification coefficient Ca). Is calculated (acceleration amplification coefficient calculation step).

  Next, by applying the acceleration amplification coefficient Ca calculated by the equation (1) to the relational expression between the bridge impact coefficient and the acceleration amplification coefficient obtained in advance, the bridge impact coefficient / impact coefficient estimated value ia (= (static + dynamic) Target deflection) / (static deflection) -1) is calculated (impact coefficient calculation step).

  Here, FIG. 3, FIG. 4 and the following formula (2) are the impact coefficient and acceleration amplification coefficient of the bridge when the RMS is used as the feature amount of the vertical acceleration of the bridge having a span length of less than 40 m and the vehicles 1a and 1b. The relationship and relational expression are shown.

  In addition, FIG. 5 and FIG. 6 and the following equation (3) are obtained by calculating the impact coefficient and acceleration amplification coefficient of the bridge when the RMS is used as the feature amount of the vertical acceleration of the bridge having a span length of 40 m or more, vehicles 1a and 1b. Relations and relational expressions are shown. In addition, v in a type | formula is a travel speed of a train.

  As shown in these figures, Equation (2), which is an estimation formula for the impact coefficient ia of a bridge with a span length of less than 40 m, is based on the actual measurement results of a 10-car train and a railway bridge. It is confirmed that the impact coefficient of 1 or more can be estimated with an error of approximately 40% or less by comparison with the numerical simulation result in consideration of the dynamic interaction.

  Equation (3), which is an estimation formula for the impact coefficient ia of a bridge with a span length of 40 m or more, is roughly equivalent to an impact coefficient of 0.8 or more by comparison with the numerical simulation result considering the vehicle / bridge dynamic interaction. It has been confirmed that estimation is possible with an error of 30% or less.

  Further, in the bridge dynamic response evaluation method of the present embodiment, when a plurality of runs are performed and there are more vehicle acceleration waveforms, the processing shown in FIG. 2 is sequentially performed and the estimated impact is stored in the bridge database. Accumulate coefficients.

  Furthermore, when there are a plurality of vehicle acceleration waveforms, the measurement date is added as information to be recorded in the bridge database. Further, the estimated impact coefficient, train speed, and bridge ID are stored in the bridge database.

  And the estimated impact coefficient of each bridge in the whole route is output (impact coefficient output process of object bridge). At this time, for example, the top number% of bridges with a large estimated impact coefficient, the top number% of bridges with a large estimated impact coefficient relative to the design impact coefficient, and the estimated impact coefficient in a bridge of the same structural type or the same span length is large. By using a ranking format that focuses on indicators, such as the top several percent of bridges, it is possible to extract weak spots based on actual structural performance and select detailed measurement locations.

  Therefore, in the bridge dynamic response evaluation method of the present embodiment, it is possible to easily and comprehensively obtain and evaluate the impact coefficient of the bridge from the acceleration responses of the leading vehicle 1a and the trailing vehicle 1b of the traveling train 1. . That is, the impact coefficient of a huge number of bridges constituting a route can be easily grasped without measuring the deflection of each bridge.

  In addition, since the impact coefficient of the bridge can be easily and comprehensively determined from the responses of the vehicles 1a and 1b of the traveling train 1, bridges constructed on national roads, railways, rivers, etc. The impact coefficient can be obtained even for bridges where it is difficult to perform deflection measurement, such as strong bridges.

  Furthermore, when the traveling of the train 1 is carried out on a daily basis, it is also possible to track the change with time of the impact coefficient.

  Therefore, according to the bridge dynamic response evaluation method of this embodiment, extraction of weak points based on actual structural performance and selection of detailed measurement points become much easier, and the efficiency of investigation and management can be greatly improved. It becomes possible.

  Further, according to the equation (2), one or more impact coefficients in a bridge with a span length of less than 40 m can be estimated with an error of about 40%. Moreover, since it is not underestimated 40% or more even if it is less than 1, a bridge with a large impact coefficient is not overlooked.

  Further, according to the equation (3), an impact coefficient of 0.8 or more in a bridge having a span length of 40 m or more can be estimated with an error of about 30%. Moreover, since it is not underestimated 30% or more even if it is less than 0.8, a bridge having a large impact coefficient is not overlooked.

  As mentioned above, although one Embodiment of the bridge dynamic response evaluation method of this embodiment of this embodiment concerning this invention was described, this invention is not limited to said one embodiment, and does not deviate from the meaning. The range can be changed as appropriate.

1 train 1a first vehicle 1b last vehicle 1c first vehicle 1d second vehicle 2 accelerometer

Claims (2)

A vehicle acceleration measuring step of providing an accelerometer for measuring vertical acceleration on each of the leading vehicle and the trailing vehicle of the train, and measuring the vertical acceleration of the leading vehicle and the trailing vehicle during traveling;
Acceleration data extraction process at the time of passing through the bridge for extracting measurement data of the accelerometer when passing through the bridge;
And acceleration amplification factor calculation step of a feature amount of the waveform of the vertical acceleration measured by the accelerometer to calculate the acceleration amplification factor by dividing by the feature amount of vertical acceleration measured by the leading vehicle of the end vehicle,
Bridge dynamic response evaluation method characterized by and a previously determined Tei was duty calculation step of fitting the acceleration amplification factor relationship of duty and acceleration amplification factor of the bridge calculates the duty cycle of the bridge . In the bridge dynamic response evaluation method according to claim 1,
The bridge dynamic response evaluation method, wherein the feature amount of the vertical acceleration is at least one of a maximum value, a minimum value, and an RMS of an acceleration waveform when passing through the bridge.

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