JP2004044116A - Remaining life estimating method for bridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hold down the waste of costs required for re-bridging and to minimize social and economical loss of re-bridging work by estimating the remaining life of a bridge in consideration of development of damage and deciding a precise maintenance and repairing plan. <P>SOLUTION: Concerning a bridge as an object, the degree of fatigue damage at the moment is obtained by measuring the traffic number of passing vehicles by each vehicle weight, the development of fatigue damage in future concerning the bridge is estimated from the degree of fatigue damage at the moment, and on the other hand, according to the future urban plan for the periphery of the bridge, a change in number of passing vehicles by each vehicle weight of the future traffic amount caused in the bridge is estimated, and the change of the degree of fatigue damage caused by the change of the future traffic amount is reflected in the development of the previously estimated future fatigue damage to correct the development of the degree of future fatigue damage. The remaining life of the bridge is estimated from the development of the degree of corrected future fatigue damage. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for estimating the remaining life of a bridge.
[0002]
[Prior art]
Many bridges constructed one after another during the high-growth period have reached their mid-life expectancy and have become noticeably obsolete, requiring repair work or replacement in some cases. Sometimes. However, it is not only expensive to replace all of them, but also long-term replacement work is expected to stagnate the surrounding urban functions and cause large social and economic losses. Therefore, instead of simply carrying out rebuilding work after the end of the useful life, an attempt is made to investigate the condition of the bridge and to formulate and execute a maintenance and repair plan to extend the remaining life based on the survey results. Has been made.
[0003]
In order to investigate the condition of the bridge, first measure the stress of the main components of the target bridge, and measure the degree of fatigue damage at the present time (find the degree of fatigue damage given to each part from the stress generated and the number of times during the measurement period) Then, assuming that this value was given to the bridge from the past to the present as the standard fatigue damage degree, assuming the accumulation of the fatigue damage degree at the present time, the bridge reaches the fatigue damage degree that requires replacement Predict how long you can use it until it reaches the end, that is, how long it will last. Also, based on the degree of damage to each part, it is estimated that repairing which part can extend the life of the entire bridge, and effective maintenance and repair work is planned and implemented.
[0004]
[Problems to be solved by the invention]
In conventional methods for predicting remaining life, the degree of damage progress is roughly grasped from the degree of fatigue damage at the time of measurement, and it is assumed that fatigue will continue to progress in the future after construction, and for how long Was predicting whether the fatigue damage level would require replacement. In addition, even when the measurement is performed a plurality of times, the interval is generally long and is measured at intervals of several years to several tens of years.
[0005]
However, the form of the city is changing every day. For example, it is possible that a vacant area will be reborn as a commercial facility that boasts a large amount of customers due to large-scale development. If such a change occurs, the traffic volume of the bridge in the vicinity will increase significantly, and the conventional method of predicting that fatigue will continue to progress as in the past will not be possible in the future. The changes cannot be factored into the forecasts, making it difficult to formulate an appropriate maintenance plan that is appropriate for the future damage of the bridge. In addition, it is conceivable that the nature of the increased vehicle will change depending on the type of new facility. Specifically, relatively light vehicles such as passenger cars increase in commercial facilities, and heavy vehicles such as large trucks increase in facilities such as factories and cargo terminals.
Since the degree of fatigue damage is determined by the generated stress value (which has a correlation with the vehicle weight) and the number of occurrences (number of passing vehicles), it is important to predict how many vehicles and how many vehicles have passed, The conventional method of evaluating with the frequency of temporary generated stress has a problem that many errors are included in predicting the degree of fatigue damage in the past and in the future.
[0006]
The present invention has been made in view of the above circumstances, and by estimating the remaining life based on the progress of damage to the bridge and formulating an appropriate maintenance and repair plan, it is possible to reduce the cost of replacement and reduce the cost of replacement. The aim is to minimize social and economic losses due to the replacement work.
[0007]
[Means for Solving the Problems]
As a means for solving the above problems, a method for estimating the remaining life of a bridge having the following configuration is employed. That is, the present invention according to claim 1 is a method for estimating a remaining life of a bridge for estimating how long the bridge can be used until the degree of fatigue damage requiring replacement is reached, that is, how long the remaining life is. ,
While measuring the number of vehicles passing by the vehicle weight at the current time for the bridge to determine the degree of fatigue damage, while estimating the progress of future fatigue damage for the bridge from the degree of fatigue damage at the current time,
Based on the future city planning around the bridge, estimate the change in the number of future traffic that will occur on the bridge by vehicle weight,
The change in the degree of fatigue damage caused by the change in the traffic volume in the future is corrected to the predicted value of the progress of future fatigue damage by reflecting the progress of the future fatigue damage estimated earlier,
The remaining life of the bridge is predicted from the corrected future progress of fatigue damage.
[0008]
According to a second aspect of the present invention, in the method for predicting a remaining life of a bridge according to the first aspect, a future change in traffic volume of the bridge based on the city plan is determined based on information of another area where the same city plan is performed. It is characterized by estimating based on
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
The method for diagnosing the remaining life of a bridge according to the present invention will be conceptually described with reference to FIG. First, the current degree of fatigue damage of a target bridge is measured, and the future fatigue damage of this bridge is estimated from the current degree of fatigue damage. For example, it is assumed that the fatigue damage level at which the bridge needs to be replaced based on its structure and the like is X, and that t0 years have passed since construction. The fatigue damage degree of this bridge at the present time is measured, and the result is assumed to be Z0 / year. If the damage degree has not been measured in the past, it is assumed that the damage has occurred at Z0 / year, the fatigue damage accumulation from the construction to the present time is Z0 × t0, and the current level is estimated to be Y. . If the degree of fatigue damage continues to increase in this state, it will reach the degree of fatigue damage X requiring replacement in t1 years after construction. That is, the remaining life of this bridge is provisionally estimated to be t1-t0 years.
[0010]
Next, future changes in traffic volume on the bridge are estimated based on information on other areas where similar city planning has already been implemented, based on the city planning planned around this bridge in the future. For example, if a city plan is to be implemented t2 years after the present time, a change in traffic volume before and after the implementation of the plan in another area where the same city plan is implemented is investigated.
[0011]
Then, if the traffic volume after the implementation of the plan has increased 1.5 times that before the implementation, it is estimated that the implementation of the city planning after t2 years will also increase the traffic volume of the bridge to 1.5 times the conventional one. The extent to which the degree of fatigue damage changes due to an increase in traffic volume is estimated based on the bridge structure. If it is estimated that the rate of increase in the degree of fatigue damage will change to twice the initially estimated rate of increase due to the implementation of city planning two years later, the progress of the degree of fatigue damage will be accelerated, and the construction will be completed three years after construction. The fatigue damage degree X requiring replacement is reached. That is, the remaining life of this bridge after incorporating the city planning is predicted to be t3-t0 years.
Similarly, it is also possible to correct a past estimated value of fatigue damage progression from a past city planning execution record.
[0012]
Next, a method for estimating the remaining life of a bridge will be described more specifically.
The major factor that causes fatigue damage to the bridge is due to the load of the vehicle passing through the bridge, and is correlated with the sum of the product of the vehicle weight and the traffic amount (量 (vehicle weight x traffic volume)). The prediction of the degree of influence corresponds to the prediction of the vehicle weight and the traffic volume of the passing vehicle.
First, a method for measuring the degree of fatigue damage of a bridge will be described with reference to FIG. At the time of the measurement, the stress acting on the main components constituting the bridge 1 (for example, a floor slab, a pier, a bridge girder, etc., which is installed on the bridge girder 2 in this embodiment) is measured. The measurement period is a period sufficient to represent the annual standard value of the traffic volume of the bridge. Generally, 3 to 6 months are preferable, but when long-term measurement is difficult, the measurement is performed for several days to several weeks including holidays and weekdays. In addition, if a true value is obtained by actual measurement by permanently installing a measuring device, the accuracy of future prediction can be improved.
If these measurement systems are configured as a remote monitoring system using communication, it is effective because it is not necessary to go to the site for data collection.
[0013]
In measuring the stress, a strain sensor 3 for capturing the strain generated in the bridge girders, a temperature sensor 4 for correcting an error due to air temperature, and a vehicle passing through the bridge girders 2 based on the measurement results of the strain sensors 3 and the temperature sensors 4 A measuring device 5 for obtaining the generated stress and estimating the weight of the passing vehicle, and recording the weight of the passing vehicle output from the measuring device 5, the weight of the vehicle passing through the bridge 1 during a certain period and the number of vehicles by the vehicle weight are calculated. A measurement system including a computer 6 for calculating and recording is used.
[0014]
In order to determine the vehicles passing through the bridge 1 by vehicle weight, the change in stress input from the strain sensor 3 to the measuring device 5 is referred to. When the vehicle passes through the bridge 1, a waveform of a stress change as shown in FIG. The weight (vehicle weight) of the vehicle that generated this waveform has a correlation with the magnitude of the change in the waveform, that is, the area of the region S cut out by the change in the waveform. The heavier the vehicle weight, the more the stress waveform changes, and the area of the region S increases.
[0015]
Therefore, the measuring device 5 calculates the area of the region S every time the waveform of the stress change is input, and estimates and outputs the weight of the vehicle that generated the waveform according to the size. The temperature sensor 4 is used to correct a change in the amount of distortion caused by a change in temperature characteristics of a member forming a pavement asphalt or a bridge due to a change in air temperature. In the computer 6, the vehicle weight input from the measuring device 5 is classified by vehicle weight having a predetermined width, and the number of vehicles passing by vehicle weight is counted. For example, the number of vehicles passing through the bridge 1 during a certain period, classified by the design reference weight of the bridge, according to the vehicle weight, is A vehicles for vehicles of 16 tons or less, B vehicles for over 16 tons, and B vehicles for over 16 tons. C units and D units are more than 25 tons (see FIG. 4).
[0016]
After counting the number of passing vehicles by vehicle weight for a period sufficient to measure the average traffic volume of the bridge, first, the degree of fatigue damage z acting on the bridge 1 during this measurement period is estimated by the following equation. .
z = a × A units + b × B units + c × C units + d × D units (a, b, c, and d are the degrees of fatigue damage when passing one vehicle in each weight category)
Next, based on the measurement period, the degree of fatigue damage (increase rate of the degree of fatigue damage) Z progressing in one year is calculated (Z = z / measurement period (year)). Assuming that the damage progresses in the past and in the future with the degree of damage Z, t1 = X / Z, and the provisional remaining life of the bridge 1 can be estimated (corresponding to the above-mentioned t1-t0).
[0017]
On the other hand, future changes in traffic volume occurring on the bridge 1 are estimated based on a city plan scheduled around the bridge 1 in the future (after the above t2 years). In the estimation, the type and approximate weight of the passing vehicle are estimated according to the type of the new facility / building. For example, when facilities such as an amusement park are established, the increase in the number of passenger cars can be predicted.When a shopping center is established, the number of cars and delivery trucks will increase. The traffic of large trucks carrying products can be expected to decrease. The increase or decrease in individual traffic is estimated based on the scale of the facility. It is also possible to refer to changes in traffic volume before and after the implementation of the plan in other areas where similar city planning has already been implemented. Specifically, if there is a bridge corresponding to bridge 1 in another area, the number of vehicles passing by the same vehicle weight is measured for this bridge in the same period as above, and if not, the location environment of bridge 1 The number of passing vehicles on the road at a point close to is counted by vehicle type, the approximate vehicle weight is set according to the vehicle type, and the number of passing vehicles by vehicle weight is estimated. The number of passing vehicles by vehicle weight after the implementation of the plan obtained in this way is replaced by the number of passing vehicles by vehicle weight before the implementation (if this is uncertain, the number of passing vehicles of bridge 1 by current vehicle weight is substituted. ), The change in the number of vehicles passing by vehicle weight is clarified, and the traffic volume of the bridge 1 after the implementation of the city planning is estimated.
[0018]
For example, in other areas, the number of vehicles weighing 16 tons or less increased by A 'and the number of vehicles exceeding 16 tons increased by B' in the measurement period (the above-mentioned measurement period for the target bridge 1) compared to before the plan was implemented. If it is assumed that C 'units have decreased by more than 20 tons and D' units have increased by more than 25 tons, this result is reflected in the number of bridges 1 that have passed by vehicle weight according to the current vehicle weight. (See FIG. 5). Then, the fatigue damage degree z ′ of the bridge 1 during a certain measurement period is estimated from the following equation from the distribution of the number of passing bridges by vehicle weight after the implementation of the city planning.
z ′ = a × (A + A ′) units + b × (B + B ′) units + c × (CC ′) units + d × (D + D ′) units Next, based on the measurement period, one year after the implementation of city planning The degree of progressive fatigue damage (increase rate of the degree of fatigue damage) Z ′ is calculated (Z ′ = z ′ / measurement period (year)).
[0019]
With the information so far, the increase rate Z of the fatigue damage degree of the bridge 1 from the time of construction to the present time, and from the present time t2 years before the implementation of the urban planning, and the increase rate Z ′ of the fatigue damage degree after the implementation of the urban planning are as follows. Presumed. Assuming that the rate of increase in the degree of fatigue damage changes with the implementation of city planning after t2 years, the period of time required to reach the degree of fatigue damage (corresponding to X above) requiring replacement from construction to construction is shortened accordingly. From the present time, the period in which the shortened amount is taken into account is the remaining life of the bridge 1 incorporating the city planning (corresponding to the above t3-t0 years) (see FIG. 1). In this way, more accurate estimation of the remaining life can be performed.
Similarly, it is possible to estimate the influence of the change in the traffic volume due to the city planning performed in the past on the remaining life of the bridge 1, so that the re-evaluation from the time of construction to the present time can be performed. Further, it is possible to estimate how much the remaining life will be prolonged when the passage of a specific vehicle (particularly a heavy vehicle) is restricted in the future so as not to pass through the bridge 1.
[0020]
By the way, in the present embodiment, the case where the strain sensor 3 is installed on the bridge girder 2 of the bridge 1 and the change in stress when the vehicle passes is simply described. The number of axles of a passing vehicle is detected by detecting the number of vehicles, and the size and weight of the vehicle are estimated from the number to obtain more detailed information on the passing vehicle. In this case, a plurality of strain sensors 3 should be installed apart from each other in the longitudinal direction of the bridge 1 to obtain a more detailed stress waveform.
[0021]
【The invention's effect】
As described above, according to the present invention, a future change in traffic volume occurring on a bridge is estimated as the number of vehicles by vehicle weight based on a future city plan around the bridge, and fatigue caused by the future traffic volume change is estimated. The progress of the future fatigue damage is corrected by reflecting the change in the damage degree to the progress of the future fatigue damage estimated earlier, and the remaining life of the bridge is predicted from the corrected progress of the future fatigue damage. By doing so, it becomes possible to more accurately predict the remaining life by incorporating changes in the environment surrounding the bridge. In addition, by grasping the more accurate remaining life and formulating an accurate maintenance and repair plan, it is possible to reduce the waste of replacement costs and to prevent social and economic losses due to replacement work. it can.
[Brief description of the drawings]
FIG. 1 is a graph used to conceptually explain the present invention and showing the relationship between the number of years elapsed since bridge construction and the degree of fatigue damage of the bridge.
FIG. 2 is a schematic diagram showing the structure of a measurement system used for stress measurement.
FIG. 3 is a graph showing a waveform of a stress change detected by passage of a vehicle.
FIG. 4 is a graph showing the number of vehicles passing by bridge weight counted on a bridge to be surveyed before implementation of city planning.
FIG. 5 is a graph showing the estimated number of passing vehicles (estimated values) by vehicle weight at a bridge to be surveyed after implementation of city planning.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bridge 3 Strain sensor 4 Temperature sensor 5 Measuring device 6 Computer

Claims (2)

A method for estimating the remaining life of a bridge that predicts how long it can be used until the bridge reaches the degree of fatigue damage that requires replacement, that is, how long the remaining life is,
While measuring the number of vehicles passing by the current vehicle weight for the bridge to determine the degree of fatigue damage, while estimating the progress of future fatigue damage for the bridge from the degree of fatigue damage at the current time,
Based on future city planning around the bridge, estimate the change in the number of vehicles by weight of future traffic that will occur on the bridge,
The change in the degree of fatigue damage caused by the change in the future traffic volume is corrected to the predicted value of the progress of future fatigue damage by reflecting the change in the degree of fatigue damage estimated earlier,
A method for predicting the remaining life of a bridge, comprising predicting the remaining life of the bridge from the corrected future progress of fatigue damage. 2. The remaining life prediction method for a bridge according to claim 1, wherein a future change in the traffic volume of the bridge based on the city planning is estimated based on information on other areas where the same city planning is performed. .

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