Method for estimating the location of deterioration and damage in bridge-mounted piping, apparatus for estimating the location of deterioration and damage in bridge-mounted piping, and computer program

Abstract

This method allows for a simple estimation of the location of deterioration and damage to bridge-mounted piping. [Solution] A method for estimating deterioration and damage locations of bridge-attached piping, comprising the steps of: measuring the time change of vibration displacement in a vertical plane including the bridge axis direction of the bridge at multiple points in the bridge axis direction of the bridge; measuring the time change of vibration displacement in a vertical plane including the pipe axis direction of the piping at multiple points on the piping attached to the bridge; and estimating the deterioration and damage locations of the piping based on the difference between the vibration displacement of the bridge and the vibration displacement of the piping, and the support position of the piping.

Description

Technical Field

[0001] The present invention relates to a method for estimating deteriorated and damaged locations of bridge-mounted pipes, an apparatus for estimating deteriorated and damaged locations of bridge-mounted pipes, and a computer program.

Background Art

[0002] Patent Document 1 describes a procedure for non-contact measurement of vibrations of in-plant structures such as pipes suspended from a building ceiling, and diagnosing the quality of their installation status. In this procedure, an alarm is issued when the value of the vibration waveform obtained by connecting the peak values of the absolute values of the vibration waveforms measured from the structure exceeds a set value, and it is determined that the installation status of the structure is poor when the difference value between the vibration waveform of the structure and the vibration waveform of the vibration source is increasing, and it is determined that the vibration source is abnormal when the difference value is constant (paragraphs 0056-0061).

[0003] Patent Document 2 describes a building determination system that detects vibrations at multiple locations from a moving image of a bridge, converts them to power by Fourier transform, and determines that the location is deteriorated when the cosine similarity with the power of adjacent elements is below a threshold value, or when the natural frequency has dropped below a preset threshold value, etc.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Infrastructure built during the period of rapid economic growth is now considered dangerous due to aging, and the importance of its maintenance and inspection has been pointed out. In particular, regarding bridges, there are concerns about the effects of fatigue due to vibration caused by chronic increases in load resulting from changes in traffic demand since their construction.

[0006] Many bridges have various types of pipes attached to them, such as water, sewage, and gas lines. These bridge-attached pipes are also subjected to vibrations along with the bridge's vibrations, making early detection of deterioration and damage caused by these vibrations crucial. However, although bridge-attached pipes are attached to the bridge, they are separate structures from the bridge itself. Their vibrations differ from those of the bridge, and the areas where deterioration and damage are expected are also completely different. Furthermore, the types of damage that occur due to the differences in vibration between the bridge and the bridge-attached pipes are also thought to differ. These include water leakage due to pipe wear, fatigue due to repeated bending acting on the bridge-attached pipes, paint peeling and rusting due to friction between the bridge-attached pipes and support members, and dents caused by collisions between the bridge-attached pipes and support members due to loosening of the bridge-attached pipes' fixings.

[0007] Inspections of bridge-attached piping can be carried out by visual inspection or tapping by inspection workers, but in many cases, it is difficult for inspection workers to get close enough to perform an inspection. Inspections require the construction of scaffolding or rope access work, which is costly, time-consuming, and in some cases, dangerous.

[0008] On the other hand, as cited in Patent Documents 1 and 2, proposals have been made to estimate the deterioration state of structures non-contact by focusing on their vibrations. However, these proposals attempt to estimate the condition of piping used in general plants or the deterioration state of bridges themselves, and no technology is known that attempts to estimate the location of deterioration and damage in accordance with the specific circumstances of bridge-attached piping.

[0009] This invention was made in view of the above circumstances, and its purpose is to easily estimate the location of deterioration and damage to bridge-attached piping. [Means for solving the problem]

[0010] The invention disclosed in this application, which aims to solve the above-mentioned problems, has various aspects, and a summary of some of the most representative aspects is as follows.

[0011] (1) A method for estimating deterioration and damage locations of bridge-attached piping, comprising: (1) measuring the time change of the amount of vibration displacement in a vertical plane including the bridge axis direction of the bridge at multiple points in the bridge axis direction of the bridge; (2) measuring the time change of the amount of vibration displacement in a vertical plane including the pipe axis direction of the piping at multiple points of the piping attached to the bridge; and (3) estimating the deterioration and damage locations of the piping based on the difference between the amount of vibration displacement for the bridge and the amount of vibration displacement for the piping, and the support positions of the piping.

[0012] (2) In (1), the estimation step involves determining the support position of the piping as a deteriorated or damaged location of the piping, depending on the magnitude of the difference in the amount of vibration displacement at the support position of the piping. A method for estimating the location of deterioration and damage in bridge-mounted piping.

[0013] (3)(2) A method for estimating deteriorated and damaged locations of bridge-attached piping, wherein the estimation step further estimates the deteriorated and damaged locations of the piping based on the maximum value of the stress acting on the piping, which is calculated from the amount of deformation of the piping obtained based on the amount of vibration displacement of the piping.

[0014] (4)(1) A method for estimating the location of deterioration and damage of bridge-attached piping, wherein the support positions of the piping are the positions where the piping is fixed to the bridge and the positions of both ends of the piping.

[0015] (5)(2) The estimation step is a method for estimating a deteriorated or damaged location of a bridge-attached pipe, wherein the support position of the pipe is determined to be a deteriorated or damaged location of the pipe according to the magnitude of the difference between the amount of vibrational movement in the bridge axis direction and the amount of vibrational movement in the pipe axis direction, and the magnitude of the difference between the amount of vibrational movement in a direction perpendicular to the bridge axis direction and the amount of vibrational movement in a direction perpendicular to the pipe axis direction.

[0016] (6) A device for estimating deterioration and damage locations of bridge-attached piping, which estimates the deterioration and damage locations of piping based on the difference between the measured values ​​of the change in vibration displacement over time in a vertical plane including the bridge axis direction of the bridge at multiple points along the bridge axis direction of the bridge, and the measured values ​​of the change in vibration displacement over time in a vertical plane including the pipe axis direction of the piping at multiple points along the piping attached to the bridge, and the support positions of the piping.

[0017] (7) A computer program to cause a computer to function as a device for estimating deteriorated and damaged locations of bridge-attached piping, which estimates the deteriorated and damaged locations of piping based on the difference between measured values ​​of the change in the amount of vibration displacement in a vertical plane including the bridge axis direction of the bridge at multiple points in the bridge axis direction of the bridge, and measured values ​​of the change in the amount of vibration displacement in a vertical plane including the pipe axis direction of the piping at multiple points in the piping attached to the bridge, and the support positions of the piping. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic side view showing a bridge and its attached piping that are subject to the implementation of the method for estimating the location of deterioration and damage to bridge-attached piping according to an embodiment of the present invention. [Figure 2] This photograph illustrates various forms in which piping is attached to bridges. [Figure 3] This table shows the types of deterioration damage estimated from vibration data, the data and estimation criteria used for the estimation, and examples of the location of the estimated deterioration damage. [Modes for carrying out the invention]

[0019] Figure 1 is a schematic side view showing a bridge 1 and its attached piping 2, which are subject to the implementation of the bridge-attached piping estimation method according to an embodiment of the present invention.

[0020] As a general structure, at both ends of the bridge 1, the main girder 103 is supported by the bearings 102 provided on the body 101 of the abutment 100. A bridge deck 104 is attached to the upper part of the main girder 103, and the ground outside the bridge, usually the access road, is gently connected to its upper surface via the expansion joint 105.

[0021] What is shown in FIG. 1 is a so-called girder bridge as a type of bridge, but other types of bridges, such as truss bridges, arch bridges, suspension bridges, etc. are also acceptable, and depending on the bridge length, piers may be provided as appropriate.

[0022] The pipe 2 is installed along the main girder 103. Specifically, the pipe 2 is supported by the main girder 103 at appropriate positions by brackets 106 fixed to the main girder 103. Also, since both ends of the pipe 2 penetrate through the parapet 107 of the abutment 100 and are connected to the outside of the bridge, both ends of the pipe 2 are restrained and supported by the abutment 100.

[0023] If necessary, an expansion joint 200 is provided in the middle of the pipe 2 as appropriate. The expansion joint is used to absorb the displacement in the length direction when the pipe 2 expands and contracts due to temperature changes between day and night and seasons, or the influence of the temperature of the fluid in the pipe, etc., so as to prevent excessive compressive or tensile stress from occurring in the pipe 2 and causing damage such as buckling or breakage.

[0024] FIG. 1 is a side view of the bridge 1, and the horizontal direction in the figure is the bridge axis direction. Strictly speaking, the main girder 103 of the bridge 1 is gently curved depending on the type of the bridge 1, and the bridge axis direction does not necessarily coincide with the horizontal direction. Also, in the vertical plane including the bridge axis, the direction perpendicular to the bridge axis direction does not necessarily coincide with the vertical direction. However, since the curvature of the main girder 103 is generally gentle, in this specification, it is not necessary to clearly distinguish between the two. Also, since the pipe 2 is installed along the bridge 1, its pipe axis direction generally coincides with the bridge axis direction.

[0025] In other words, in this specification, when we refer to the bridge axis direction or the pipe axis direction, we may actually use the horizontal direction instead. Also, when we refer to a direction perpendicular to the bridge axis direction or perpendicular to the pipe axis direction in a vertical plane, we may actually use the vertical direction instead. In other words, in light of the technical aspects of the present invention, in the following, the bridge axis direction and pipe axis direction may be understood to include the horizontal direction, and the direction perpendicular to the bridge axis direction and perpendicular to the pipe axis direction in a vertical plane may be understood to include the vertical direction.

[0026] Now, because the load on bridge 1 fluctuates due to vehicles and other objects passing over it, vibrations occur, causing the entire main girder 103 to deform dynamically. Since pipe 2 is supported by the main girder 103, it is also affected by the vibrations of bridge 1 and deforms dynamically. However, except for the fact that bridge 1 and pipe 2 are supported by brackets 106, they are independent and separate structures, so the manner of their vibrations differs from each other, and their deformations are not identical. Therefore, it is thought that due to this inconsistency in deformation caused by vibrations, there will be areas in pipe 2 that are prone to partial deterioration and damage. If it is possible to easily estimate such areas prone to deterioration and damage, or areas where deterioration and damage is thought to have occurred, then inspection workers can be dispatched according to the estimation results to inspect or repair those areas, thereby maintaining the integrity of the pipes at minimal cost.

[0027] Therefore, in this embodiment, both the time change in the amount of vibration displacement in a vertical plane including the bridge axis direction of the bridge 1 is measured at multiple points along the bridge axis direction of the bridge 1, and the time change in the amount of vibration displacement in a vertical plane including the pipe axis direction of the pipe 2 is measured at multiple points along the pipe 2 attached to the bridge 1.

[0028] This measurement is performed by means appropriate to the type of bridge 1, the mounting method of the piping 2, its bridge location, and the surrounding topography. Figure 2 is a photograph illustrating various types of mounting methods for the piping 2 on bridge 1. Figure 2(a) is a so-called side mounting, similar to the example in Figure 1, where the piping 2 is mounted on the side of the main girder 103. Figure 2(b) is a so-called bottom mounting, where the piping 2 is mounted so as to be suspended from the underside of the main girder 103. Figure 2(c) is a so-called box girder internal mounting, where the piping 2 is mounted inside the main girder 103.

[0029] When the piping 2 is exposed to the outside of the bridge 1 and visible, as shown in Figure 1 with side or bottom mounting, optical vibration measurement is possible. Optical vibration measurement methods include taking video with a camera and obtaining vibration waveforms at each point from the movement of feature points or markers attached to the main girder 103 or piping 2, or laser measurement. If optical vibration measurement methods are difficult to use, vibration meters or accelerometers can be appropriately installed on the main girder 103 or piping 2, or optical fibers can be laid along the main girder 103 or piping 2 and the deformation of the optical fibers can be estimated from the optical response.

[0030] The vibration measurement conditions are determined according to the type of deterioration damage expected to the piping 2. When targeting deterioration damage caused by vibrations from traffic on the bridge 1, vibration data should be acquired for 10 to 300 seconds, more preferably 30 to 90 seconds, at a frequency of 10 to 120 Hz, more preferably 30 to 90 Hz, during times when traffic volume is expected to be high. When targeting deterioration damage caused by deformation due to the difference in temperature between day and night, vibration data should be acquired for 1 to 7 days at a frequency of once every 1 to 120 minutes, more preferably every 30 to 90 minutes. When targeting deterioration damage caused by deformation due to seasonal temperatures, vibration data should be acquired throughout the year at a frequency of, for example, every week, from one day to one month.

[0031] Furthermore, for both bridge 1 and pipe 2, vibration measurements should be taken at approximately 20 to 1000 measurement points along the bridge axis or pipe axis. It is preferable that the positions of the vibration measurement points in the bridge axis direction and the number of measurement points are the same for bridge 1 and pipe 2, but they do not necessarily have to coincide. It is acceptable as long as the measurements are taken at positions and at a number of points that complement each other to the extent that the total amount of deformation due to vibration of bridge 1 and pipe 2 can be compared along the bridge axis or pipe axis.

[0032] Therefore, the vibration data obtained from this vibration measurement of bridge 1 and pipe 2 shows the amount of vibration displacement in a vertical plane including the bridge axis direction or pipe axis direction over time, at multiple measurement points in the bridge axis direction or pipe axis direction. Furthermore, since both are measured simultaneously, it is possible to compare the deformation that occurred in bridge 1 and the deformation that occurred in pipe 2 at a certain time (a certain moment), and to obtain the difference between them.

[0033] Once these vibration data, namely the measurement results of the amount of vibration displacement for bridge 1 and the amount of vibration displacement for pipe 2, are obtained, the location of deterioration and damage to pipe 2 can be estimated based on this vibration data and the mounting conditions for pipe 2. Here, the mounting conditions for pipe 2 include the support position of pipe 2 and the insertion position of the expansion joint 200. The position where pipe 2 is supported on the main girder 103 by bracket 106 corresponds to the support position here, and the positions at both ends of pipe 2 that penetrate the parapet 107 of the abutment 100 also correspond to the support position here.

[0034] Figure 3 shows a table listing the types of deterioration damage estimated from vibration data, the data and estimation criteria used for the estimation, and examples of the estimated location of the deterioration damage.

[0035] For the types of deterioration and damage described in the top two sections, wear due to friction and damage due to impact to pipe 2, the difference between the vibration displacement of bridge 1 and the vibration displacement of pipe 2 is used as data for estimation, and the location of deterioration and damage is estimated based on the magnitude of the difference at the bracket support position.

[0036] In most cases, the bracket 106 is a rigid member and behaves as one with the main girder 103, whereas the pipe 2 may be fixedly supported to the bracket 106 so as to be one with it, or it may be supported in a movable manner that allows relative movement. Therefore, whether the pipe 2 is fixedly supported or supported in a movable manner at its support position, if the amount of vibrational movement of the pipe 2 and the main girder 103 are the same under certain conditions, then at that support position, the pipe 2 behaves as one with the main girder 103, so the amount of vibrational movement of the bridge 1 and the amount of vibrational movement of the pipe 2 should be the same, and the difference should be zero. On the other hand, at locations where fixed support is loose, or at support positions where movable support is provided, a difference may occur between the amount of vibrational movement of the pipe 2 and the amount of vibrational movement of the bridge 1.

[0037] If this differential vibration is observed in the bridge axis direction or the pipe axis direction, it is considered that the pipe 2 is rubbing against the inside of the bracket 106 in the pipe axis direction. Repeated rubbing can cause deterioration damage to the pipe 2, such as a reduction in wall thickness due to wear of the pipe 2, or corrosion due to rust caused by peeling of the paint coating. Therefore, as shown in the top row of the table in Figure 3, the position where this difference is greatest is estimated as the location of deterioration damage suspected to be due to frictional wear of the pipe 2, depending on the magnitude of the difference between the vibration displacement in the bridge axis direction and the vibration displacement in the pipe axis direction at the bracket support position.

[0038] Furthermore, if this differential vibration is observed in a direction perpendicular to the bridge axis direction or perpendicular to the pipe axis direction, it is considered that the pipe 2 is moving within the space inside the bracket 106 and repeatedly colliding with the inner surface of the bracket 106. Such repeated collisions can cause damage such as abrasion and cracking. Therefore, as shown in the second row from the top of the table in Figure 3, the position where this difference is greatest is estimated as the location of deterioration damage suspected to be caused by collisions of the pipe 2, depending on the magnitude of the difference between the amount of vibrational displacement perpendicular to the bridge axis direction and the amount of vibrational displacement perpendicular to the pipe axis direction at the bracket support position.

[0039] Thus, the estimation of the deterioration and damage locations of pipe 2, as shown in the top row and second row from the top of the table in Figure 3, is possible by using the measurement results of both the vibration displacement of bridge 1 and the vibration displacement of pipe 2, and based on the difference between the two and the support position of pipe 2. Furthermore, by determining the support position as a deterioration and damage location of pipe 2 according to the magnitude of the difference between the vibration displacement in the bridge axis direction and the vibration displacement in the pipe axis direction, and the magnitude of the difference between the vibration displacement in the direction perpendicular to the bridge axis direction and the vibration displacement in the direction perpendicular to the pipe axis direction, it is possible to separately estimate different deterioration and damage phenomena that may occur at the support position of pipe 2.

[0040] The third row from the top in the table in Figure 3, showing damage to pipe 2 due to bending, is estimated using vibration data of pipe 2. The location where the dynamic stress acting on pipe 2 is at its maximum along its entire length is considered the location where failure due to metal fatigue, etc., is most likely to occur, and this location is estimated as the location of deterioration damage.

[0041] Here, the vibration data of pipe 2 in the direction perpendicular to the pipe axis indicates the displacement of pipe 2 in the shear direction at a given moment. By taking the second derivative of this displacement curve in the direction of the pipe axis and multiplying it by the Young's modulus of the material and the second moment of area, the bending moment generated in pipe 2 can be obtained. By dividing the bending moment by the section modulus, the maximum bending stress at that cross section can be calculated. Since the maximum value of this normal stress at a cross section can be calculated over the entire length of pipe 2, this maximum value becomes the maximum stress calculated from the deformation of pipe 2. In other words, the location of the deterioration damage to pipe 2 due to bending is estimated based on the maximum stress acting on pipe 2, which is calculated from the deformation of pipe 2.

[0042] If the location of deterioration and damage is estimated using the method shown in the table in Figure 3, then, based on the type of deterioration and damage indicated and its location, inspection workers can actually go to Bridge 1, inspect the piping 2 at the location of the deterioration and damage, and carry out necessary repairs such as correcting improper support by bracket 106, repainting the piping 2, and replacing materials and parts, thereby maintaining the piping 2 in good condition.

[0043] The estimation of deterioration and damage locations shown in Table 3 may be performed automatically using a device. Specifically, by inputting the measured values ​​of the time change in the amount of vibration displacement in a vertical plane including the bridge axis direction of the bridge 1, and the amount of vibration displacement in a vertical plane including the pipe axis direction of the pipe 2 at multiple points on the pipe attached to the bridge 1, the device estimates and outputs the type of deterioration and damage and the location of deterioration and damage using the estimation criteria shown in Figure 3, thereby enabling efficient and rapid estimation of deterioration and damage locations. In particular, with respect to the types of deterioration and damage shown in the top two rows of Figure 3, the device estimates the deterioration and damage locations of the pipe 2 based on the difference between the measured values ​​of the time change in the amount of vibration displacement in a vertical plane including the bridge axis direction of the bridge 1 and the measured values ​​of the time change in the amount of vibration displacement in a vertical plane including the pipe axis direction of the pipe 2 at multiple points on the pipe 2 attached to the bridge 1, and the support position of the pipe 2.

[0044] Such a device for estimating the deterioration and damage locations of bridge-attached piping can be realized using a general-purpose computer with a processor, memory, and input / output capabilities. Specifically, by running a computer program on the computer that estimates the deterioration and damage locations of piping 2 based on the difference between the measured values ​​of the time change in the amount of vibration displacement in a vertical plane including the bridge axis direction of bridge 1 at multiple points along the bridge axis direction of bridge 1, and the measured values ​​of the time change in the amount of vibration displacement in a vertical plane including the pipe axis direction of piping 2 at multiple points along piping 2 attached to bridge 1, as well as the support positions of piping 2, the computer can be used as a device for estimating the deterioration and damage locations of bridge-attached piping.

[0045] Such a computer-based device for estimating the location of deterioration and damage in bridge-attached piping does not necessarily need to operate standalone; it may be implemented as an application running on a server accessible via a network. In that case, as long as a data communication environment is in place, the vibration data obtained at the vibration measurement point of bridge 1 can be transmitted via the network to a server functioning as a device for estimating the location of deterioration and damage in bridge-attached piping. The server will then immediately return the estimated location of deterioration and damage, which can be used to diagnose the soundness of piping 2 and estimate the location of deterioration and damage on the spot, thus facilitating inspection and maintenance of bridge-attached piping.

[0046] It should be noted that the specific configuration of Bridge 1, the types of deterioration damage to be estimated, and the estimation criteria shown in this embodiment described above are provided as examples only, and are not intended to limit the technical scope of the present invention to such specific configurations. Depending on the actual structure of the bridge to which the piping is attached, and the content requiring inspection, the specific configuration, the types of resulting damage to be estimated, and the estimation criteria may be changed, deleted, or added as appropriate. [Explanation of Symbols]

[0047] 1 Bridge, 2 Piping, 100 Abutment, 101 Main structure, 102 Bearing, 103 Main girder, 104 Bridge deck, 105 Expansion joint, 106 Bracket, 107 Parapet, 200 Expansion joint.

Claims

1. The steps include measuring the time change in the amount of vibrational displacement in a vertical plane including the bridge axis direction of the bridge at multiple points along the bridge axis direction of the bridge, The steps include measuring the time change in the amount of vibration displacement in a vertical plane including the pipe axis direction of the piping at multiple points on the piping attached to the bridge, A step of estimating the location of deterioration and damage to the piping based on the difference between the amount of vibration displacement of the bridge and the amount of vibration displacement of the piping, and the support position of the piping. A method for estimating the location of deterioration and damage in bridge-attached piping.

2. The estimation step involves determining the support position as a location of deterioration or damage to the pipe, based on the magnitude of the difference in the amount of vibration displacement at the support position of the pipe. A method for estimating the location of deterioration and damage to bridge-attached piping according to claim 1.

3. The estimation step further estimates the location of deterioration and damage in the piping based on the maximum stress acting on the piping, which is calculated from the deformation of the piping obtained based on the amount of vibration displacement of the piping. A method for estimating the location of deterioration and damage to bridge-attached piping according to claim 2.

4. The support positions for the piping are the positions where the piping is fixed to the bridge and the positions at both ends of the piping. A method for estimating the location of deterioration and damage to bridge-attached piping according to claim 1.

5. The estimation step involves determining the support position as a location of deterioration or damage to the piping, based on the magnitude of the difference between the amount of vibration displacement in the bridge axis direction and the amount of vibration displacement in the pipe axis direction at the support position of the piping, and the magnitude of the difference between the amount of vibration displacement in the direction perpendicular to the bridge axis direction and the amount of vibration displacement in the direction perpendicular to the pipe axis direction. A method for estimating the location of deterioration and damage to bridge-attached piping according to claim 2.

6. A device for estimating deterioration and damage locations of bridge-attached piping, which estimates the deterioration and damage locations of piping based on the difference between measured values ​​of the change in vibration displacement over time in a vertical plane including the bridge axis direction of the bridge at multiple points along the bridge axis direction of the bridge, and measured values ​​of the change in vibration displacement over time in a vertical plane including the pipe axis direction of the piping at multiple points along the piping attached to the bridge, and the support positions of the piping.

7. A computer program for causing a computer to function as a device for estimating deterioration and damage locations of bridge-attached piping, which estimates the deterioration and damage locations of piping based on the difference between measured values ​​of the time change in the amount of vibration displacement in a vertical plane including the bridge axis direction of the bridge at multiple points in the bridge axis direction of the bridge, and measured values ​​of the time change in the amount of vibration displacement in a vertical plane including the pipe axis direction of the piping at multiple points in the piping attached to the bridge, and the support positions of the piping.

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