Damage evaluation method and residual performance evaluation method

Abstract

To provide a damage evaluation method capable of evaluating a damage state of a reinforced concrete structure in which a reinforcement sheet is attached to a surface of a concrete structure.SOLUTION: A damage evaluation method for evaluating a damage state of a reinforcement beam 106 having a beam 105 and a reinforcement part 1 including a continuous fiber sheet 3 attached on a surface of the beam 105 comprises: a distortion distribution acquisition process of acquiring distortion distribution of the continuous fiber sheet 3 using an optical fiber sensor 13 installed on the continuous fiber sheet 3; and a damage state estimation process of estimating positions of peeled parts 22 of the reinforcement beam 106 and the like on the basis of the distortion distribution acquired in the distortion distribution acquisition process.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a damage assessment method and a residual performance assessment method. [Background technology]

[0002] Conventionally, there is known a reinforced concrete structure that is reinforced by attaching a reinforcing sheet such as a fiber-reinforced sheet to the surface of the concrete structure (see, for example, Patent Document 1 below). With such a reinforcement structure, the reinforcing sheet can be adhered to the surface of the concrete structure without using anchors or the like, so that the concrete structure can be reinforced without being damaged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-069624 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a load such as an earthquake acts on this type of reinforced concrete structure, damage such as cracks in the concrete structure and the associated peeling of the reinforcing sheet may occur. When such damage occurs, the performance of the reinforced concrete structure decreases, so it is necessary to determine, for example, whether the structure can be continued to be used or whether re-reinforcement is necessary. However, if the crack occurs in a location hidden by the reinforcing sheet, it is difficult to visually confirm the damaged state. In other words, even if the performance of the reinforced concrete structure is reduced due to damage, this may not be immediately recognized by visual inspection. Therefore, the present invention aims to provide a damage evaluation method and a remaining performance evaluation method that can evaluate the damaged state of the reinforced concrete structure in a reinforced concrete structure in which a reinforcing sheet is bonded to the surface of the concrete structure. [Means for solving the problem]

[0005] The gist of the present invention is as follows.

[0006] [1] A damage assessment method for evaluating a damage state of a reinforced concrete structure having a concrete structure and a reinforcing portion including a reinforcing sheet adhered to the surface of the concrete structure, the damage assessment method comprising: a condition distribution acquisition process for acquiring a condition distribution of the reinforcing sheet using a sensor consisting of an optical fiber cable installed on the reinforcing sheet; and a damage state estimation process for estimating the damage state of the reinforced concrete structure based on the condition distribution acquired in the condition distribution acquisition process.

[0007] [2] The damage assessment method described in [1], wherein the sensor has a plurality of measurement points arranged in the longitudinal direction of the sensor, and the sensor is capable of acquiring the strain distribution of the reinforcing sheet in the longitudinal direction as the condition distribution of the reinforcing sheet by acquiring the strain of the reinforcing sheet at each of the measurement points.

[0008] [3] A damage assessment method described in [1] or [2], wherein the reinforcing sheet is adhered to the surface of the concrete on which shear force acts, so that the reinforcing portion forms a shear reinforcement structure, and a plurality of the sensors extending in a predetermined direction on the reinforcing sheet are installed on the reinforcing sheet in an array in a direction perpendicular to the predetermined direction, and in the condition distribution acquisition process, the strain distribution of the reinforcing sheet in the predetermined direction is acquired as the condition distribution of the reinforcing sheet.

[0009] [4] A damage assessment method described in [2] or [3], wherein in the damage state estimation process, a portion where a predetermined strain has occurred in the reinforcing sheet is estimated as a peeled portion of the adhesive joint between the concrete structure and the reinforcing sheet based on the strain distribution.

[0010] [5] A residual performance evaluation method for evaluating the remaining performance of the reinforced concrete structure using the damage evaluation method described in [4], wherein the remaining performance is evaluated based on the shortest distance between the peeled portion estimated in the damage state estimation step in the damage evaluation method and an end of the adhesive joint in the specified direction.

[0011] [6] A damage assessment method described in [4] or [5], wherein in the damage state estimation process, the center position of the peeled portion is estimated as the position of a crack occurring in the concrete structure.

[0012] [7] A damage evaluation method described in any one of [2] to [6], further comprising a second distribution acquisition process of acquiring a strain distribution of the concrete structure using a second sensor located between the concrete structure and the reinforcing sheet, installed on the concrete structure and consisting of an optical fiber cable, wherein in the damage state estimation process, the damage state of the reinforced concrete structure is estimated based on the strain distribution of the reinforcing sheet obtained in the state distribution acquisition process and the strain distribution of the concrete structure obtained in the second distribution acquisition process.

[0013] [8] The damage assessment method described in any one of [1] to [7], wherein a plurality of the sensors are connected in series to each other. Effect of the Invention

[0014] According to the present invention, it is possible to provide a damage assessment method and a remaining performance assessment method capable of evaluating the damage state of a reinforced concrete structure in which a reinforcing sheet is adhered to the surface of the concrete structure. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view showing a bridge to which a damage assessment method and a residual performance assessment method according to a first embodiment are applied. FIG. [Diagram 2]1A is a cross-sectional view showing an example of a reinforcing girder, FIG. 1B is a cross-sectional view showing another example of the reinforcing girder, and FIG. 1C is a side view thereof. [Diagram 3] (a) is a cross-sectional view showing an example of the vicinity of the adhesive joint taken along one optical fiber sensor, (b) is the strain distribution of the continuous fiber sheet, (c) is a cross-sectional view showing another example of the vicinity of the adhesive joint taken along one optical fiber sensor, and (d) is the strain distribution of the continuous fiber sheet. [Figure 4] FIG. 2A is a diagram showing an example of a peak in a strain distribution, and FIG. 2B is a diagram showing an example of a strain section in the strain distribution. [Diagram 5] This is a side view of the reinforcement part viewed from the Y direction, with an example of an estimated crack and peeling part superimposed. [Figure 6] FIG. 11 is an exploded perspective view showing a reinforcement part of a girder to which the damage assessment method and the residual performance assessment method of the second embodiment are applied. [Figure 7] (a) is a cross-sectional view showing an example of the vicinity of the adhesive joint, and (b) is the strain distribution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [First embodiment] Hereinafter, an embodiment of the damage assessment method and the remaining performance assessment method according to the present invention will be described in detail with reference to the drawings. The damage assessment method and the remaining performance assessment method of this embodiment are applied to a bridge 100 shown in FIG. 1. In the following, X, Y, and Z may be used in the description, with the bridge axis direction of the bridge 100 being the X direction, the direction perpendicular to the bridge axis being the Y direction, and the vertical direction being the Z direction. As shown in FIG. 1, the bridge 100 includes a pier 101, a beam 103 that protrudes from the upper end of the pier 101 in the direction perpendicular to the bridge axis, a plurality of girders 105 that are supported on the beam 103 and extend in the bridge axis direction, and a deck 107 that is supported on the plurality of girders 105. The pier 101, the beam 103, the girder 105, and the deck 107 are all reinforced concrete structures.

[0017] In the bridge 100, reinforcement structures are constructed for seismic reinforcement of each part, such as seismic reinforcement of the pier 101, bending reinforcement and shear reinforcement of the beam 103, bending reinforcement and shear reinforcement of the girder 105, and bending reinforcement of the deck 107. Of these, the damage assessment method and the remaining performance assessment method of this embodiment are intended to assess the girder 105 reinforced by the reinforcing part 1. Hereinafter, the girder 105 reinforced by the reinforcing part 1 is referred to as a "reinforced girder 106." In other words, the reinforcing girder 106 (reinforced concrete structure) includes the girder 105 (concrete structure) and the reinforcing part 1 that reinforces the girder 105.

[0018] FIG. 2(a) is a cross-sectional view showing an example of the reinforcing girder 106. FIG. 2(b) is a cross-sectional view showing another example of the reinforcing girder 106, and FIG. 2(c) is a side view thereof. As described above, the reinforcing girder 106 includes the girder 105, which is a reinforced concrete structure, and the reinforcing part 1 that reinforces the girder 105. The reinforcing part 1 has a continuous fiber sheet 3 (reinforcing sheet) bonded to the surface of the girder 105. The continuous fiber sheet 3 is a sheet made of FRP (Fiber Reinforced Plastics), and is light, thin, has high tensile strength, and has a small increase in dead load in the structure to be reinforced, so that it is generally used suitably for reinforcing concrete structures. This type of continuous fiber sheet may also be simply called an "FRP sheet." As shown in FIG. 2(a), the continuous fiber sheet 3 may be arranged to cover three surfaces, namely the bottom surface and both side surfaces 9, 9 of the girder 105, and to wrap the girder 105. Alternatively, as shown in FIG. 2(b), the continuous fiber sheet 3 may be disposed only on the side surfaces 9,9.

[0019] In this embodiment, the reinforcement part 1 will be described with attention to a portion constructed on one side surface 9 of the girder 105. The side surface 9 of the girder 105 is a vertical surface extending long in the bridge axis direction and perpendicular to the Y direction. As described above, the reinforcement part 1 has a continuous fiber sheet 3 bonded to the side surface 9. The reinforcement part 1 is a shear reinforcement structure constructed on the side surface 9 on which shear force acts within the surface of the girder 105. The continuous fiber sheet 3 has a vertical width slightly narrower than that of the girder 105, and is bonded to the range from the upper end to the lower end of the side surface 9. In addition, in the X direction, the continuous fiber sheet 3 is bonded to the side surface 9 over a predetermined length of the reinforcing girder 106. The entire bonded portion 10 between the continuous fiber sheet 3 and the side surface 9 corresponds to the entire target area of ​​the damage assessment method and the residual performance assessment method of this embodiment.

[0020] In the reinforcing portion 1, as shown in Figs. 2(b) and 2(c), an optical fiber cable 11 is installed on the surface of the continuous fiber sheet 3. The optical fiber cable 11 is installed on the surface opposite to the adhesive surface between the continuous fiber sheet 3 and the beam 105. The optical fiber cable 11 is adhered to the surface of the continuous fiber sheet 3 so as to be integrated with the continuous fiber sheet 3, and can expand and contract in accordance with the expansion and contraction of the continuous fiber sheet 3. Note that instead of adhering the optical fiber cable 11 to the continuous fiber sheet 3, an FRP sheet into which an optical fiber cable has been woven in advance may be adhered to the surface of the beam 105. This method omits the process of adhering the optical fiber cable.

[0021] One end of the optical fiber cable 11 is connected to a measuring instrument 15. An analyzing device 17 is further connected to the measuring instrument 15. The measuring instrument 15 inputs pulsed light into the optical fiber cable 11, receives various scattered lights returning from each position (each measuring point P) in the longitudinal direction of the optical fiber cable 11, and transmits information on the intensity, wavelength, etc. of the received scattered lights to the analyzing device 17. The scattered lights include Rayleigh scattered light and Brillouin scattered light. Examples of the measuring instrument 15 include an OTDR (Optical Time Domain Reflectometer) that uses Rayleigh scattered light and a BOTDR (Brillouin Optical Time Domain Reflectometer) that uses Brillouin scattered light. Note that in the actual optical fiber cable 11, measuring points P are set at equal intervals over the entire longitudinal direction of the optical fiber cable 11, but only some of the measuring points P are illustrated in FIG. 2(c). Moreover, the measurement points P in FIG. 2(c) are shown only diagrammatically, and in an actual optical fiber cable 11, the measurement points P are present at intervals even smaller than those in FIG. 2(c).

[0022] The analysis device 17 is a computer including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The analysis device 17 analyzes the intensity and wavelength of the scattered light at each position in the longitudinal direction of the optical fiber cable 11 based on the principle that the intensity and wavelength of the scattered light depend on the strain applied to the optical fiber cable 11. Through such analysis, the analysis device 17 acquires the strain occurring at each position (each measurement point P) in the longitudinal direction of the optical fiber cable 11 at a predetermined pitch. Therefore, by using the optical fiber cable 11 integrated with the continuous fiber sheet 3 as a strain sensor, it is possible to acquire the strain distribution of the continuous fiber sheet 3 in the extension direction of the optical fiber cable 11.

[0023] 2(c), the optical fiber cable 11 extends in a zigzag pattern on the continuous fiber sheet 3. More specifically, the optical fiber cable 11 on the continuous fiber sheet 3 extends in a rectangular wave pattern over the entire range in the X direction of the reinforcing beam 106 while regularly bending so that portions extending in the Z direction and portions extending in the X direction are alternately connected. The portion of the optical fiber cable 11 extending in the Z direction extends over almost the entire vertical width of the continuous fiber sheet 3.

[0024] In the damage evaluation method of the present embodiment, each of the many portions of the optical fiber cable 11 that mainly extend in the Z direction is used as an optical fiber sensor 13. Each optical fiber sensor 13 includes a plurality of measurement points P included in the optical fiber cable 11 described above. Therefore, the optical fiber sensor 13 acquires the Z direction strain of the continuous fiber sheet 3 at each measurement point P, thereby making it possible to acquire the Z direction strain distribution of the continuous fiber sheet 3. That is, in each optical fiber sensor 13, the Z direction strain of the continuous fiber sheet 3 at the position of the optical fiber sensor 13 is acquired. In the reinforcing section 1 having such an optical fiber cable 11, it can be said that a plurality of optical fiber sensors 13 extending in the Z direction are arranged in the X direction and installed on the continuous fiber sheet 3. And, it can be said that the plurality of optical fiber sensors 13 are connected in series with the portions of the optical fiber cable 11 extending in the X direction interposed between them. It can also be said that the optical fiber cable 11 has a plurality of optical fiber sensors 13 arranged in the X direction. The arrangement pitch of the optical fiber sensors 13 in the X direction may be, for example, approximately the same as the arrangement interval of the shear reinforcement bars of the girder 105.

[0025] In the bridge 100 as described above, during an earthquake or the like, a shear force acts on the reinforcing girder 106 in the Z direction. This shear force may damage the reinforcing girder 106. Specifically, the shear force may cause cracks on the side surface 9 of the girder 105. In addition, peeling may occur at the adhesive portion 10 between the side surface 9 and the continuous fiber sheet 3, starting from the cracked portion. When such damage occurs, the performance of the reinforcing girder 106, such as the shear strength, decreases, so it is necessary to determine whether the bridge 100 can be used after the earthquake occurs and whether re-reinforcement is necessary. For this reason, it is necessary to evaluate the damage state of the reinforcing girder 106 and the remaining performance remaining in the reinforcing girder 106 at the present time. The damage evaluation method of this embodiment evaluates the damage state of the reinforcing girder 106, and includes a strain distribution acquisition process and a damage state estimation process, which will be described next.

[0026] (Strain distribution acquisition process) The strain distribution acquisition process acquires information on the residual strain of the continuous fiber sheet 3 remaining after the occurrence of an earthquake. In the strain distribution acquisition process, the strain distribution of the continuous fiber sheet 3 is acquired using a large number of optical fiber sensors 13 installed on the continuous fiber sheet 3. A one-dimensional Z-direction strain distribution of the continuous fiber sheet 3 along the optical fiber sensor 13 is obtained by one optical fiber sensor 13. Specifically, as described above, pulsed light is incident on the optical fiber cable 11 from the measuring instrument 15, and scattered light returning from each position in the longitudinal direction of the optical fiber cable 11 is received by the measuring instrument 15. Information on the intensity, wavelength, etc. of the scattered light received by the measuring instrument 15 is transmitted to the analyzing device 17. Each position in the longitudinal direction of the optical fiber cable 11 can be associated with each position in the Z direction on the optical fiber sensor 13, so that the one-dimensional Z-direction strain distribution of the continuous fiber sheet 3 along the optical fiber sensor 13 is obtained in the analyzing device 17. Then, by obtaining the Z direction strain distribution as described above from each of the numerous optical fiber sensors 13 arranged in the X direction, the two-dimensional strain distribution of the continuous fiber sheet 3 within the XZ plane can be obtained.

[0027] (Damage state estimation process) In the damage state estimation step, the damage state of the reinforcing girder 106 is estimated based on the strain distribution of the continuous fiber sheet 3 obtained in the above-mentioned strain distribution acquisition step. In this case, the damage state of the reinforcing girder 106 includes the state of cracks in the girder 105 and the state of peeling of the adhesive portion 10 (peeling of the continuous fiber sheet 3 from the girder 105). More specifically, the damage state includes the position of the crack in the girder 105 and the position of peeling of the adhesive portion 10 (peeling of the continuous fiber sheet 3 from the girder 105). The principle of estimating the position of the crack in the girder 105 and the position of peeling of the adhesive portion 10 from the strain distribution obtained by the optical fiber sensor 13 is as follows.

[0028] FIG. 3(a) shows a cross-sectional view of the vicinity of the adhesive joint 10 taken along one optical fiber sensor 13. When the girder 105 is subjected to a shear force due to an earthquake, a crack 21 may occur in the girder 105 as shown in FIG. 3(a). The crack 21 divides the side surface 9 of the girder 105 in the Z direction within the above cross section. Then, the continuous fiber sheet 3 is locally stretched in the Z direction at the position of the crack 21, and a strain in the continuous fiber sheet 3 in the Z direction is generated and concentrated at this position. In this case, the strain distribution acquired by the optical fiber sensor 13 has a peak 31 at the position of the crack 21 as shown in FIG. 3(b).

[0029] Furthermore, when the crack 21 opens, the strain of the continuous fiber sheet 3 increases in the vicinity of the crack 21, and the adhesive stress between the girder 105 and the continuous fiber sheet 3 increases. When the adhesive stress exceeds the adhesive strength, peeling of the adhesive joint 10 occurs. That is, as shown in FIG. 3(c), the peeled portion 22 of the adhesive joint 10 may spread in the Z direction from the crack 21. Then, the adhesive stress is not transmitted to the continuous fiber sheet 3 in the peeled portion 22. Therefore, in this case, the strain distribution acquired by the optical fiber sensor 13 has a strain section 32 showing a substantially constant strain over the entire range of the peeled portion 22, as shown in FIG. 3(d). Even after the load caused by the earthquake is removed, the strain caused by the crack 21 and the peeled portion 22 as described above remains as a residual strain, and continues to appear in the strain distribution acquired by the optical fiber sensor 13, as shown in FIG. 3(b) and FIG. 3(d).

[0030] Based on this knowledge, if the analytical device 17 obtains a distribution having a peak 31 as shown in Figure 3(b), it is estimated that a crack 21 in the girder 105 has occurred at the position of the peak 31 in the cross section along the optical fiber sensor 13.

[0031] Furthermore, when the analysis device 17 obtains a distribution having a strain section 32 that spreads in the Z direction over a certain range as shown in Fig. 3(d), the above-mentioned strain section 32 is estimated to be the peeled portion 22 in the cross section along the optical fiber sensor 13. Furthermore, it is estimated that a crack 21 in the girder 105 has occurred at the center position 33 in the Z direction of the above-mentioned strain section 32.

[0032] In the analysis device 17, peaks 31 and strain sections 32 appearing in the strain distribution are distinguished and determined as follows: Fig. 4(a) is an example of a strain distribution showing an enlarged view of the vicinity of peak 31, and Fig. 4(b) is an example of a strain distribution showing an enlarged view of the vicinity of strain section 32. For example, as shown in Fig. 4(a), a distribution state in which the strain continuously decreases as one moves away from the point where the strain is maximum on either side is determined to be peak 31. On the other hand, as shown in Fig. 4(b), a distribution state in which the strain fluctuates irregularly is determined to be strain section 32.

[0033] In the damage state estimation step, the crack 21 and the peeled portion 22 are estimated in each cross section along each optical fiber sensor 13 by the calculation of the analysis device 17, and the positions of the crack 21 and the peeled portion 22 are estimated two-dimensionally throughout the entire reinforcement part 1. FIG. 5 is a side view of the reinforcement part 1 from the Y direction, including an example of the crack 21 and the peeled portion 22 estimated here. In the damage state estimation step in this embodiment, for example, as shown in FIG. 5, the position of the crack 21 extending obliquely on the side surface 9 and the position of the peeled portion 22 extending obliquely in a band shape centered on the crack 21 are estimated. The positions of the crack 21 and the peeled portion 22 estimated in this way may be converted into a visual diagram, for example, and output to a display device provided with the analysis device 17. A user can recognize the damage state of the reinforcement girder 106 by looking at the screen on the display device.

[0034] The remaining performance evaluation method of this embodiment uses the above-mentioned damage evaluation method to evaluate the remaining performance (shear strength) remaining in the reinforcement girder 106 at the present time after an earthquake, for example. In addition to the above-mentioned damage evaluation method, the remaining performance evaluation method of this embodiment includes a remaining performance estimation step, which will be described next.

[0035] (Residual performance estimation process) In the remaining performance estimation process, the remaining shear strength of the reinforcing girder 106 is evaluated based on the shortest distance between the peeled portion 22 estimated in the above damage state estimation process and the end of the adhesive joint 10 in the Z direction. The principle of estimating the shear strength based on the above shortest distance is as follows.

[0036] Consider a case where a load such as an earthquake acts on the reinforcing girder 106 in the state shown in FIG. 5. When the peeled portion 22 grows in the Z direction due to this load and reaches the upper end edge 10t or the lower end edge 10s of the adhesive portion 10, the continuous fiber sheet 3 is completely peeled off from the side surface 9. Then, due to the peeling of the continuous fiber sheet 3, the reinforcing effect of the reinforcing portion 1 is lost, leading to shear failure of the reinforcing girder 106. Therefore, it can be considered that the shortest length L of the unpeeled portion between the peeled portion 22 and the upper end edge 10t or the lower end edge 10s (hereinafter referred to as "peeling margin") corresponds to the margin (i.e., shear strength) of the reinforcing girder 106 until shear failure. The peeling margin L is the shortest distance in the Z direction between the peeled portion 22 and the upper end edge 10t or the lower end edge 10s.

[0037] In other words, there is a correlation between the above-mentioned peeling margin length L and the remaining shear strength of the reinforcing girder 106. In the example of Fig. 5, the peeled portion 22 is located relatively close to the upper edge 10t, so the peeling margin length L corresponds to the distance between the upper edge 10t and the point of the peeled portion 22 that is closest to the upper edge 10t.

[0038] Based on this knowledge, the analysis device 17 calculates an estimate of the remaining shear strength of the reinforcing girder 106 through a predetermined correlation based on the peeling margin length L. The above correlation may be determined in advance by prior experiments or the like and stored in the analysis device 17. The estimated shear strength thus determined may be output to a screen of a display device provided in the analysis device 17 and presented to a user as an evaluation value of the remaining performance of the reinforcing girder 106. Based on the presented information, the user can quantitatively determine the remaining performance of the reinforcing girder 106.

[0039] The value of the peeling margin length L can be considered as a kind of index showing the shear strength of the reinforcing girder 106. Therefore, it is not essential that the value of the peeling margin length L is converted into the value of the shear strength of the reinforcing girder 106 as described above, and the peeling margin length L may be treated as an evaluation value of the remaining performance of the reinforcing girder 106. That is, for example, the value of the peeling margin length L may be output on a screen of a display device provided in the analysis device 17.

[0040] According to the damage evaluation method of the present embodiment as described above, even if the cracks 21 and the peeled off portion 22 occur in the invisible portion of the reinforcing girder 106 covered with the continuous fiber sheet 3, the damage state of the reinforcing girder 106, such as the positions of the cracks 21 and the peeled off portion 22, can be estimated and evaluated. According to the remaining performance evaluation method of the present embodiment, the remaining performance (shear strength) currently existing in the reinforcing girder 106 as described above can be evaluated. Therefore, the user can judge whether the bridge 100 can be used after the occurrence of an earthquake and the need for re-reinforcement. In particular, since the reinforcing girder 106 is a member that bears a shear force and shear failure of the reinforcing girder 106 has a large effect on the entire bridge 100, it is highly necessary to correctly evaluate the remaining performance. In addition, the state of deterioration of the reinforcing portion 1 in the reinforcing girder 106 due to aging and environmental effects can also be detected.

[0041] As a reinforcing structure for making it easier to visually check the damage state of the reinforcing girder 106, for example, a reinforcing structure in which the continuous fiber sheet 3 is adhered only to one side surface 9 of the reinforcing girder 106, or a reinforcing structure in which the continuous fiber sheet 3 is adhered in stripes at intervals in the X direction can be considered. However, in these reinforcing structures, the reinforcing effect may be insufficient because the reinforcing area is small. In contrast, according to the damage evaluation method and the remaining performance evaluation method of this embodiment, the damage state and remaining performance can be evaluated even when the continuous fiber sheet 3 is adhered to the entire surface of the girder 105. However, the damage evaluation method and the remaining performance evaluation method of this embodiment can also be applied to the reinforcing structure in which the continuous fiber sheet 3 is adhered only to one side surface 9 of the reinforcing girder 106, or the reinforcing structure in which the continuous fiber sheet 3 is adhered in stripes at intervals in the X direction, as described above.

[0042] Second Embodiment Next, a second embodiment of the damage assessment method and remaining performance assessment method of the present invention will be described. In addition to the first embodiment described above, the damage assessment method and remaining performance assessment method of this embodiment further includes a second strain distribution acquisition step described below. Also, the damage state estimation step of this embodiment differs from the first embodiment in that information obtained in the second strain distribution acquisition step is further utilized. Other points are the same as those of the first embodiment, so duplicated explanations will be omitted.

[0043] 6 is an exploded perspective view of the reinforcing portion 201 according to this embodiment. As shown in FIG. 6, the reinforcing portion 201 further includes an optical fiber cable 42 in addition to the reinforcing portion 1 of the first embodiment. The optical fiber cable 42 is provided separately from the optical fiber cable 11, and is installed on the side surface 9 of the beam 105 at the bonding portion 10. The optical fiber cable 42 is sandwiched between the side surface 9 and the continuous fiber sheet 3, and is bonded to the side surface 9 so as to be integrated therewith. The optical fiber cable 42 exists so as to be embedded in the adhesive layer that bonds the continuous fiber sheet 3 to the side surface 9, but since the optical fiber cable 42 is bonded to the side surface 9 with an adhesive force stronger than that of the adhesive layer, it can expand and contract in accordance with the expansion and contraction of the beam 105.

[0044] The optical fiber cable 42 has a rectangular wave shape overlapping with the optical fiber cable 11 when viewed from the Y direction, and has a plurality of second optical fiber sensors 43 positioned so as to overlap with each of the optical fiber sensors 13. One end of the optical fiber cable 42 is connected to the measuring instrument 15 and the analysis device 17, and the analysis device 17 obtains a one-dimensional Z-direction strain distribution of the girder 105 along each of the second optical fiber sensors 43.

[0045] (Second strain distribution acquisition process) In the second strain distribution acquisition process, a strain distribution in the Z direction of the girder 105 on the side surface 9 is acquired using a large number of second optical fiber sensors 43 arranged in the X direction.

[0046] (Damage state estimation process) In the damage state estimation step, the state of damage to the reinforcing girder 106 (cracks in the girder 105, peeling of the adhesive portion 10) is estimated based on the strain distribution in the Z direction of the continuous fiber sheet 3 obtained by the optical fiber sensor 13 in the strain distribution acquisition step and the strain distribution in the Z direction of the girder 105 obtained by the second optical fiber sensor 43 in the second strain distribution acquisition step. The principle by which the state of damage to the reinforcing girder 106 is estimated from the strain distribution of the continuous fiber sheet 3 and the strain distribution of the girder 105 is as follows.

[0047] If the continuous fiber sheet 3 and the girder 105 are completely bonded, the strains of both should be the same. In this case, it can be estimated that the portion where the strain of the continuous fiber sheet 3 differs from the strain of the girder 105 is the peeled portion 22. As a specific example, as illustrated in FIG. 7(b), a strain distribution S1 is obtained by the strain distribution acquisition step, and a strain distribution S2 is obtained by the second strain distribution acquisition step. That is, the strain distribution S1 is the strain distribution of the continuous fiber sheet 3, and the strain distribution S2 is the strain distribution of the girder 105. In this case, the analysis device 17 compares the strain distribution S1 with the strain distribution S2, and estimates that the portion S9 where there is a difference between the two is the peeled portion 22, as shown in FIG. 7(a). In addition, since the peak 47 appearing in the strain distribution S2 is considered to be caused by the crack 21 in the girder 105, the analysis device 17 may estimate that the position of the above-mentioned peak 47 is the position of the crack 21 that has occurred in the girder 105.

[0048] According to the damage assessment method and remaining performance assessment method of this embodiment as described above, by comparing the strain between the continuous fiber sheet 3 and the girder 105 using the optical fiber sensor 13 and the second optical fiber sensor 43, it is possible to more accurately estimate the positions of the cracks 21 and peeled off portions 22, and ultimately to more accurately assess the remaining performance of the reinforcing girder 106.

[0049] Third Embodiment Next, a third embodiment of the damage assessment method and remaining performance assessment method of the present invention will be described. The damage state estimation process and remaining performance estimation process in this embodiment differ from the first embodiment in that the state of the shear reinforcement (not shown) of the girder 105 is estimated as the damage state of the reinforcing girder 106, instead of the state of cracks in the girder 105 and the state of peeling of the adhesive portion 10. Since the other points are the same as those in the first embodiment, duplicated explanations will be omitted. The damage state estimation process in this embodiment is as follows.

[0050] (Damage state estimation process) In the damage state estimation step, the degree of strain or yield of the shear reinforcement of the girder 105 is estimated based on the strain distribution of the continuous fiber sheet 3 obtained in the above-mentioned strain distribution acquisition step. The principle of estimating the degree of strain or yield of the shear reinforcement of the girder 105 from the strain distribution obtained by each optical fiber sensor 13 is as follows. In the strain distribution acquisition step, for example, the strain distribution of the continuous fiber sheet 3 as shown in FIG. 3(d) is obtained. By integrating the strain of this strain distribution, the displacement amount (elongation) of the continuous fiber sheet 3 can be obtained. If it is assumed that the concrete part of the girder 105 is a rigid body, the elongation of the continuous fiber sheet 3 is equal to the width of the crack 21. In addition, there is a correlation between the width of the crack 21 and the strain of the shear reinforcement of the girder 105. Therefore, if the correlation between the width of crack 21 and the strain of the shear reinforcement of girder 105 is known, it is possible to obtain the strain of the shear reinforcement of girder 105 based on the strain distribution obtained by each optical fiber sensor 13. The correlation between the width of crack 21 and the strain of the shear reinforcement of girder 105 as described above may be obtained in advance by prior experiments or the like and stored in analysis device 17.

[0051] According to the above principle, in the damage state estimation step of this embodiment, the analysis device 17 estimates the strain of the shear reinforcement of the girder 105 based on the strain distribution of the continuous fiber sheet 3. The estimated strain of the shear reinforcement thus obtained is the evaluation value of the damage state of the reinforcement part 1 in the damage evaluation method of this embodiment. Since the yield strain of the shear reinforcement is a known value that depends on the material of the shear reinforcement, the analysis device 17 compares the estimated strain obtained above with the yield strain to determine whether the shear reinforcement has yielded.

[0052] (Residual performance estimation process) In the remaining performance estimation process, if the shear reinforcement has not yielded, the analysis device 17 calculates the margin to yield (for example, the difference between the above-mentioned estimated strain value and the yield strain). This margin is an index showing the remaining performance of the reinforcing girder 106. If the shear reinforcement has yielded, the degree of yield (for example, the difference between the above-mentioned estimated strain value and the yield strain) is calculated. The calculated margin to yield and the degree of yield are output to a screen, for example, on a display device provided in the analysis device 17, and presented to the user. The user can quantitatively determine the remaining performance of the reinforcing girder 106 based on the presented information.

[0053] [Fourth embodiment] Next, a fourth embodiment of the damage assessment method and the remaining performance assessment method of the present invention will be described. This embodiment is different from the first embodiment in that a DAS (Distributed Acoustic Sensing) measurement process described later is performed instead of the strain distribution acquisition process in the first embodiment. In the vibration distribution acquisition process in this embodiment, an optical fiber sensor 13 is used as a sensor for sensing vibration in the DAS measurement. In addition, the damage state estimation process in this embodiment is also different from the first embodiment as described later. Since the other points are the same as those in the first embodiment, duplicated explanations will be omitted. The DAS measurement process and the damage state estimation process in this embodiment are as follows. In the DAS measurement process, a DAS measuring instrument (not shown) is connected to the optical fiber cable 11 instead of the measuring instrument 15 in FIG. 2.

[0054] (DAS measurement process) When the reinforcing beam 106 vibrates due to an external force applied from the outside, the vibration is transmitted to the optical fiber sensor 13 via the continuous fiber sheet 3, and the optical fiber sensor 13 dynamically expands and contracts (vibrates). The external force may be intentionally applied by hitting the reinforcing beam 106 with a hammer or the like, or may be a traffic load on the bridge 100. When the external force is applied, the analysis device 17 obtains a distribution of the vibration state of the continuous fiber sheet 3 in multiple cross sections along each optical fiber sensor 13 based on the scattered light from the optical fiber cable 11. That is, a two-dimensional distribution of the vibration state of the continuous fiber sheet 3 in the XZ plane is obtained. The above-mentioned DAS measurement may also be called a "distributed vibration measurement method," "distributed acoustic sensing," "distributed vibration sensing," or the like.

[0055] (Damage state estimation process) Here, it is considered that the vibration characteristics are different between the portion of the continuous fiber sheet 3 that has peeled off from the side surface 9 of the girder 105 and the portion that has not peeled off. For example, it is considered that the portion of the continuous fiber sheet 3 that has peeled off from the side surface 9 of the girder 105 will have a lower vibration frequency in the DAS measurement compared to the portion that has not peeled off. Based on this principle, in the damage state estimation process, it is estimated that the portion of the continuous fiber sheet 3 that has a lower vibration frequency in the DAS measurement process than the surrounding area is the peeled portion 22.

[0056] According to the damage assessment method and remaining performance assessment method of this embodiment, it is possible to assess the damage state of the reinforcing girder 106, where the time of damage cannot be identified, such as deterioration of the reinforcing part 1 due to environmental factors such as salt damage and frost damage.

[0057] [Reference form] Next, a damage assessment method and a residual performance assessment method according to a reference embodiment will be described. In the strain distribution acquisition step in the first embodiment, the strain distribution of the continuous fiber sheet 3 is acquired using an optical fiber sensor 13, but in the strain distribution acquisition step in this reference embodiment, the strain distribution of the continuous fiber sheet 3 is acquired by a sampling moiré method. Other points are the same as in the first embodiment, so duplicated explanations will be omitted.

[0058] (Strain distribution acquisition process) The strain distribution acquisition process using the sampling moire method is performed, for example, as follows. Immediately after the reinforcement work of the reinforcing girder 106 (immediately after the continuous fiber sheet 3 is bonded to the girder 105), a lattice pattern is drawn on the surface of the continuous fiber sheet 3, and this lattice pattern is photographed by a digital camera. Thereafter, an image of the lattice pattern photographed again at the time of evaluating the damage state of the reinforcing girder 106 is superimposed on the image of the lattice pattern immediately after the reinforcement work, and the resulting stripe pattern (moire stripes) is analyzed to measure the displacement and strain of the continuous fiber sheet 3 compared to immediately after the reinforcement work of the reinforcing girder 106. When this sampling method is used, the strain distribution in the photographed range can be obtained two-dimensionally, so that the peeled portion 22 can be estimated with higher accuracy.

[0059] If the continuous fiber sheet 3 is black or a color close to black and it is difficult to draw a lattice pattern on the continuous fiber sheet 3, the surface of the continuous fiber sheet 3 may be painted in a light color after construction, and then the lattice pattern may be drawn on the topcoat material that is generally used in the adhesive construction method for continuous fiber sheets.

[0060] The present invention can be embodied in various forms including the above-mentioned embodiment and various modifications and improvements based on the knowledge of a person skilled in the art. In addition, it is also possible to configure modified examples by utilizing the technical matters described in the above-mentioned embodiment. The configurations of the respective embodiments may be used in appropriate combination. For example, the damage assessment method and the residual performance assessment method of the present invention may be applied not only to the girder 105 but also to the reinforcement parts of the bridge pier 101, the beam 103, or the deck 107. Furthermore, the damage assessment method and the residual performance assessment method of the present invention are not limited to bridges and can be applied to various concrete structures. [Explanation of symbols]

[0061] 1,201...reinforcement part, 3...continuous fiber sheet (reinforcement sheet), 9...side, 10...adhesive part, 10t...upper edge, 11...optical fiber cable, 13...optical fiber sensor, 21...crack, 22...peeled part, 42...optical fiber cable, 43...second optical fiber sensor, 105...girder (concrete structure), 106...reinforcing girder (concrete structure), L...peeling length (shortest distance), P...measurement point.

Claims

1. A damage evaluation method for evaluating a damage state of a reinforced concrete structure having a concrete structure and a reinforcing portion including a reinforcing sheet adhered to a surface of the concrete structure, comprising: a state distribution acquisition step of acquiring a state distribution of the reinforcing sheet using a sensor configured with an optical fiber cable and installed on the reinforcing sheet; a damage state estimation step of estimating a damage state of the reinforced concrete structure based on the state distribution obtained in the state distribution acquisition step; A damage assessment method comprising:

2. The sensor has a plurality of measurement points arranged in a longitudinal direction of the sensor, The damage assessment method according to claim 1 , wherein the sensor is capable of acquiring the strain of the reinforcing sheet at each of the measurement points, thereby acquiring the longitudinal strain distribution of the reinforcing sheet as the state distribution of the reinforcing sheet.

3. The reinforcing sheet is adhered to the surface of the concrete on which a shear force acts, so that the reinforcing portion forms a shear reinforcement structure, A plurality of the sensors extending in a predetermined direction on the reinforcing sheet are arranged in a direction perpendicular to the predetermined direction and installed on the reinforcing sheet, In the state distribution acquisition step, The damage assessment method according to claim 2 , wherein a strain distribution in the specified direction of the reinforcing sheet is acquired as the state distribution of the reinforcing sheet.

4. In the damage state estimation step, The damage assessment method according to claim 3 , wherein a portion of the reinforcing sheet where a predetermined strain occurs is estimated as a peeled portion of an adhesive portion between the concrete structure and the reinforcing sheet based on the strain distribution.

5. A residual performance evaluation method for evaluating a residual performance of the reinforced concrete structure by using the damage evaluation method according to claim 4, A residual performance evaluation method in which the residual performance is evaluated based on the shortest distance between the peeled portion estimated in the damage state estimation process in the damage evaluation method and the end of the adhesive portion in the specified direction.

6. In the damage state estimation step, The damage assessment method according to claim 4 , wherein a center position of the peeled portion is estimated as a position of a crack occurring in the concrete structure.

7. a second distribution acquisition step of acquiring a strain distribution of the concrete structure using a second sensor that is located between the concrete structure and the reinforcing sheet and that is installed in the concrete structure and is made of an optical fiber cable; In the damage state estimation step, The damage assessment method described in claim 3, wherein a damage state of the reinforced concrete structure is estimated based on the strain distribution of the reinforcing sheet obtained in the state distribution acquisition process and the strain distribution of the concrete structure obtained in the second distribution acquisition process.

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