Tensile detection device

Abstract

To provide a compression detection device that can ascertain ex post facto the maximum tensile force that a concrete structure has previously received.SOLUTION: A tensile detection device according to one embodiment is a tensile detection device 1 embedded in a concrete structure S with multiple structural reinforcements. The concrete structure S has a fixing area A where fixing parts S5 of the multiple structural reinforcements are provided. The tensile detection device 1 is embedded in concrete S4 and is equipped with a detection device 11 for detecting residual strain left in the fixing area A with tensile force against the concrete S4 and a core material 12 to which the detection device 11 is fixed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a tensile detection device for detecting tensile force acting on a concrete structure.

Background Art

[0002] Japanese Patent No. 6145344 describes an impact detection method and a detection device for detecting an impact in a structure using an FBG sensor (Fiber Bragg Grating Sensor). This detection device includes an FBG sensor attached to a structure, an optical fiber amplifier, an optical circulator, and a coupler. A strain measurement optical filter, a temperature measurement optical filter, and a photoelectric converter are connected to the coupler. When strain occurs in the structure, the reflected light from the FBG sensor is input to a light source converter via the optical fiber amplifier and the coupler, and the application history of the impact force on the structure is acquired by the light source converter.

[0003] Japanese Patent No. 4187250 describes a method and a system for diagnosing a structure using an optical fiber. In this system, an optical fiber is attached to a target member of the structure, and the initial strain of the target member is measured by the optical fiber. The optical fiber continuously monitors the strain history of a specific part of the target member and diagnoses the soundness of the structure from the initial strain and the strain history.

[0004] Japanese Unexamined Patent Application Publication No. 2013 - 250120 describes a method for detecting damage to a structure. In the damage detection method, a damage detection device is attached to the lower surface of a bridge girder disposed between a pair of bridge piers. The damage detection device includes a first base and a second base fixed to the surface to be inspected of the bridge girder, and a detection member disposed between the first base and the second base. As the detection member, an optical fiber incorporating an optical strain detection means is used.

[0005] Japanese Patent Application Laid-Open No. 2001-59796 describes a strength prediction device for an oil tank. The strength prediction device includes a base on which the side plate of the oil tank is erected, an optical fiber laid on the side plate of the oil tank, a strain measuring device, and a monitoring device. The strain measuring device measures the strain associated with the external force applied to the oil tank via the optical fiber. The monitoring device monitors the presence or absence of cracks based on the amount of strain measured by the strain measuring device.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, in a concrete structure, there is a problem that it is difficult to retrospectively grasp the tensile force applied to the concrete structure due to an earthquake or the like. For example, as described above, a method of detecting the strain of a concrete structure using an optical fiber cable is known. However, the strain detected by the optical fiber cable is the strain at the moment when the pulsed light is incident, and it is impossible to grasp the past history or the maximum response of the tensile force received by the concrete. That is, there is a current situation where it is impossible to retrospectively grasp the maximum tensile force received in the past with respect to the behavior of a concrete structure due to an earthquake or the like.

[0008] An object of the present disclosure is to provide a compression detection device capable of retrospectively grasping the maximum tensile force received by a concrete structure in the past.

Means for Solving the Problems

[0009] The tensile detection device according to the present disclosure is a tensile detection device embedded in a concrete structure provided with structural reinforcement materials such as a plurality of reinforcing bars and steel materials. In the concrete structure, reinforcing bars, steel materials, etc. are arranged so as to be able to resist tensile forces, and a fixing region for fixing these structural reinforcement materials is provided. The tensile detection device is embedded in the concrete of the concrete structure, and includes a detection device that detects the residual strain remaining in the fixing region along with the tensile force applied to the concrete, and a core material to which the detection device is fixed. The concrete structure has a column portion extending in the vertical direction and an expansion portion expanding at the lower end of the column portion. The concrete structure includes a plurality of structural reinforcement materials extending in the vertical direction inside the column portion and the expansion portion. The lower ends of the plurality of structural reinforcement materials are defined as a fixing region having a fixing portion. The fixing region is provided in the expansion portion. The core material extends together with the plurality of structural reinforcement materials. The core material is composed of a material with a yield strength higher than that of the structural reinforcing material. The diameter of the core material is smaller than the diameter of the structural reinforcing material. The detection device extends along the structural reinforcement material. The detection device measures the distribution of the residual strain of the core material after the tensile force generated in the core material due to the horizontal seismic force applied to the concrete structure acts.

[0010] In this tensile detection device, the concrete structure has structural reinforcement materials. The concrete structure has a fixing region provided with a fixing portion of the structural reinforcement material. The tensile detection device includes a detection device and a core material, and the detection device fixed to the core material detects the residual strain associated with the tensile force. Therefore, by detecting the residual strain left in the fixing region by the detection device fixed to the core material, it is possible to grasp whether or not the tensile force that the concrete has received so far has been equal to or greater than a predetermined value. That is, since the magnitude of the residual strain generated in the fixing region varies depending on the strength of the tensile force, by detecting the residual strain by the detection device, it is possible to grasp whether or not the tensile force that the concrete has received so far has been equal to or greater than a predetermined value. Therefore, it is possible to retrospectively grasp the past history or the maximum response of the tensile force received by the concrete.

[0011] The detection device may be an optical fiber cable fixed to the core material. In this case, the residual strain in the fixing region can be detected with high precision by the optical fiber cable. In the optical fiber cable, since strain can be detected along the portion where the optical fiber cable contacts, for example, the distribution of the residual strain in the direction in which the structural reinforcing material extends can be detected. Therefore, since the optical fiber cable can detect the distribution of the residual strain along the structural reinforcing material with high precision, the history of the tensile force received in the past can be grasped with higher precision.

[0012] Core Since the yield strength of the material is higher than the yield strength of the structural reinforcing material, the amount of residual strain in the fixing region can be more reliably made proportional to the maximum tensile force received in the past. Therefore, the past history or the maximum response of the tensile force can be detected with higher precision.

[0013] The core material has an extending portion extending along the structural reinforcing material and a branching portion branching from the extending portion in the fixing region, and the branching portion may yield when the tensile force on the concrete is equal to or greater than a predetermined value. In this case, by the detection device detecting the presence or absence of the yield of the branching portion, it is possible to easily grasp whether or not the tensile force transmitted to the fixing region was equal to or greater than a predetermined value.

Advantages of the Invention

[0015] According to the present disclosure, the maximum tensile force received by the concrete structure in the past can be grasped retrospectively.

Brief Description of the Drawings

[0016]

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Mode for Carrying Out the Invention

[0017] Hereinafter, taking a concrete structure using reinforcing bars as a structural reinforcing material as an example, embodiments of the tensile detection device according to the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted as appropriate. Also, the drawings may be drawn with some parts simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those described in the drawings.

[0018] FIG. 1(a) is a longitudinal sectional view schematically showing a concrete structure S in which a tensile detection device 1 according to an embodiment is embedded. As shown in FIG. 1(a), the tensile detection device 1 detects a tensile force acting on the concrete structure S in a state of being embedded in the concrete structure S. As an example, the concrete structure S has a footing. That is, the concrete structure S has a column portion S1 extending in the vertical direction D1 and an extension portion S2 extending at the lower end of the column portion S1. For example, the concrete structure S is a pier.

[0019] The concrete structure S has a plurality of structural reinforcing bars S3 and concrete S4. The plurality of structural reinforcing bars S3 are an example of a structural reinforcing material. The structural reinforcing bar S3 is, for example, the main reinforcing bar of the concrete structure S. As an example, the structural reinforcing bar S3 extends along the vertical direction D1. The concrete structure S has a fixing region A where the fixing portions S5 of the plurality of structural reinforcing bars S3 are provided. The fixing region A is provided, for example, in the footing (expansion portion S2) of the concrete structure S.

[0020] The tensile detection device 1 is arranged, for example, along the structural reinforcing bar S3. The tensile detection device 1 is embedded in a concrete structure S including a plurality of structural reinforcing bars S3. The tensile detection device 1 includes a detection device 11 embedded in the concrete S4, a core material 12 to which the detection device 11 is fixed, and a measuring instrument 13 provided at an end of the detection device 11. In the present embodiment, an example in which a part of the plurality of structural reinforcing bars S3 is the core material 12 will be described.

[0021] In the present embodiment, the detection device 11 is an optical fiber cable. The measuring instrument 13 measures the deformation of the core material 12 as strain by measurement using Rayleigh scattered light, for example, using the detection device 11. However, the measuring instrument 13 may measure the strain by measurement using Brillouin scattered light using the detection device 11. When the measuring instrument 13 inputs the measurement light K1 to the detection device 11, backward scattered light K2 is generated in the detection device 11. The spectrum (intensity for each frequency) of the backward scattered light K2 changes due to strain. The intensity of the backward scattered light K2 is smaller than the intensity of the measurement light K1. In the measurement using Rayleigh scattered light, the strain generated in the detection device 11 is detected by measuring the change in the spectrum of the backward scattered light K2. Since the backward scattered light K2, which is Rayleigh scattered light, has a higher intensity than Brillouin scattered light, it has the advantages of high accuracy and being relatively resistant to light loss. In the detection device 11, for example, the strain of the core material 12 can be detected with an accuracy of 1 μ strain.

[0022] Alternatively, instead of the measurement using the Brillouin scattered light or the measurement using the Rayleigh scattered light described above, the measuring instrument 13 may measure the strain of the core material 12 by the optical frequency domain reflectometry method (OFDR method: Optical Frequency Domain Reflectometry). In the OFDR method, the detection device 11 is linearly frequency-modulated, and the information on the distance to the light reflection point in the detection device 11 is measured as a beat signal by an interferometer. In the OFDR method, using the detection device 11, the strain generated in the core material 12 can be measured in detail distributively with a measurement interval of 0.6 mm and a spatial resolution of 0.6 mm with high precision of ±1 μm or more.

[0023] FIG. 1(b) is a longitudinal sectional view schematically showing the behavior when a horizontal seismic force F acts on the concrete structure S. When a horizontal seismic force F acts on the concrete structure S, a tensile force corresponding to the bending moment distribution is generated in the structural reinforcing bars S3 of the concrete structure S, and the tensile force is also transmitted to the fixing region A inside the footing to which the structural reinforcing bars S3 are fixed, according to the acting tensile force and the adhesion stress of the structural reinforcing bars S3.

[0024] A part of the tensile force transmitted to the fixing region A remains as the residual strain of the structural reinforcing bars S3 even after the horizontal seismic force F has disappeared (after unloading) due to the adhesion stress of the structural reinforcing bars S3. The tensile detection device 1 detects the maximum response of the tensile force acting on the concrete structure S by measuring the range where the residual strain occurs and the degree of the residual strain. That is, when a tensile force acts on the core material 12, adhesion failure occurs according to the acting tensile force. When a tensile force acts on the core material 12, adhesion failure occurs, accompanied by a locally irreversible decrease in the adhesion force according to the acting tensile force. Since this influence remains as residual strain even in the state where the horizontal seismic force F has been unloaded, the tensile detection device 1 detects this residual strain.

[0025] Fig. 2(a) is a diagram schematically showing the maximum response of the tensile force on the structural reinforcing bar S3 when subjected to the horizontal seismic force F. As shown in Fig. 2(a), in the structural reinforcing bar S3 of the concrete structure S, the tensile force increases from above in the column part S1 toward the extension part S2, and the tensile force reaches its maximum at the base S6 of the column part S1. Then, the tensile force decreases as it goes downward from the base S6.

[0026] Fig. 2(b) is a diagram schematically showing the residual strain when the tensile force acts on the structural reinforcing bar S3 of the concrete structure S as shown in Fig. 2(a). In Figs. 2(a) and 2(b), the case of a small tensile force is shown by a dashed line, and the case of a large tensile force is shown by a one-dot chain line, respectively. As shown in Figs. 2(a) and 2(b), when a tensile force acts on the structural reinforcing bar S3, residual strains Z1 and Z2 then occur in the structural reinforcing bar S3.

[0027] Residual strains Z1 and Z2 occur in both the case of a large tensile force and the case of a small tensile force, but the residual strain Z2 in the case of a large tensile force is larger than the residual strain Z1 in the case of a small tensile force. Also, the residual strain Z2 in the case of a large tensile force extends more vertically downward than the residual strain Z1 in the case of a small tensile force, and the tip position P where the adhesion breaks differs according to the magnitude of the tensile force (horizontal seismic force F). In the case of a large tensile force, the tip position P becomes deeper compared to the case of a small tensile force. In the tensile detection device 1 according to the present embodiment, it is possible to grasp the maximum response of the tensile force acting on the concrete structure S by detecting the tip position P (lower end position) of the residual strain.

[0028] By the detection device 11 detecting the residual strain of the core material 12 (structural reinforcing bar S3), it is possible to grasp how much tensile force has occurred in the concrete structure S in the past. That is, by measuring the distribution of the residual strain of the core material 12 with the detection device 11, the maximum value of the tensile force acting on the concrete structure S can be estimated.

[0029] Next, the effects obtained from the tensile detection device 1 according to the present embodiment will be described in detail. As shown in FIGS. 1(a), 1(b), 2(a), and 2(b), in the tensile detection device 1, the concrete structure S has a plurality of structural reinforcing bars S3. The concrete structure S has a fixing region A provided with fixing portions S5 of the plurality of structural reinforcing bars S3. The tensile detection device 1 includes a detection device 11 and a core material 12, and the detection device 11 fixed to the core material 12 detects residual strains Z1, Z2 accompanying the tensile force.

[0030] Therefore, by detecting the residual strains Z1, Z2 left in the fixing region A by the detection device 11 fixed to the core material 12, it is possible to grasp whether or not the tensile force that the concrete S4 has received so far is equal to or greater than a predetermined value. That is, since the magnitude of the residual strains Z1, Z2 generated in the fixing region A changes depending on the strength of the tensile force, by the detection device 11 detecting the residual strains Z1, Z2, it is possible to grasp whether or not the tensile force that the concrete S4 has received so far is equal to or greater than a predetermined value. The above "predetermined value" indicates a predetermined value of the tensile force corresponding to the position of the discrete measurement points.

[0031] Therefore, since it is possible to grasp the maximum tensile force received by the concrete S4 by detecting the residual strains Z1, Z2 left in the fixing region A, it is possible to retrospectively grasp from the residual strains Z1, Z2 whether or not the maximum tensile force received by the concrete S4 in the past is equal to or greater than a predetermined value. Therefore, it is possible to retrospectively grasp the past history or the maximum response of the tensile force received by the concrete S4.

[0032] As described above, the detection device 11 may be an optical fiber cable fixed to the core material 12. In this case, the residual strain distribution in the fixing region A can be detected with high resolution by the optical fiber cable. Therefore, the history of the tensile force can be grasped with higher accuracy. In the optical fiber cable, since strain can be detected along the location where the optical fiber cable contacts, for example, the distribution of the residual strain in the direction in which the structural reinforcing bar S3 extends can be detected. Therefore, the optical fiber cable can detect the distribution of the residual strains Z1 and Z2 along the structural reinforcing bar S3 with high resolution, so that the history of the tensile force can be grasped with higher accuracy.

[0033] In the present embodiment, the core material 12 is a part of the plurality of structural reinforcing bars S3. In this case, a part of the plurality of structural reinforcing bars S3 can be used as the core material 12 to which the detection device 11 is fixed. Therefore, the tensile detection device 1 can be easily installed.

[0034] (Second Embodiment) Next, the tensile detection device 21 according to the second embodiment will be described with reference to FIGS. 3 and 4. A part of the configuration of the tensile detection device 21 overlaps with a part of the configuration of the tensile detection device 1 described above. Therefore, hereinafter, the description overlapping with the configuration of the tensile detection device 1 will be given the same reference numerals and will be appropriately omitted.

[0035] The tensile detection device 21 includes a detection device 11, a measuring instrument 13, and a core material 22 embedded in the concrete S4 separately from the plurality of structural reinforcing bars S3. The core material 22 is made of a material having a higher yield strength than the structural reinforcing bar S3. In this case, the core material 22 can make the adhesion break section proportional to the tensile force and the maximum strain, and the detection of the tensile force can be continued even if the structural reinforcing bar S3 yields.

[0036] The core material 22 may be composed of a material capable of ensuring negative friction after unloading. Here, "negative friction" refers to the friction that acts to prevent unloading in the process of unloading the tensile force acting on the core material 22. Also, the adhesion-breaking performance of the core material 22 may be due to the adhesion of the core material 22 to the concrete S4. Further, the tensile detection device 21 may further include a coating material that covers the surface of the core material 22, and the tensile detection device 21 may evaluate the adhesion to the concrete S4 through the coating material.

[0037] The core material 22 has, for example, a stranded wire structure. In this case, since irregularities are formed on the surface of the core material 22, the adhesion performance of the core material 22 to the concrete S4 can be enhanced. As an example, the core material 22 is a carbon fiber cable. In this case, the core material 22 is a cable formed by compounding and twisting carbon fibers and a thermosetting resin.

[0038] The material of the core material 22 may contain aramid fibers or basalt fibers. In this case, the adhesion performance of the core material 22 can be further enhanced. Also, the adhesion-breaking section with respect to the tensile force can be controlled by the elastic modulus of the core material 22. For example, by increasing the elastic modulus, the tensile force is more likely to be transmitted to the fixing region A, the adhesion-breaking section becomes larger, and it becomes easier to detect. However, the core material 22 may be composed of a material other than the above, and may be, for example, a PC steel wire or a deformed PC steel bar.

[0039] The core material 22 preferably has a small diameter so as not to affect the bending characteristics. The diameter of the core material 22 is, for example, 10 mm or more and not more than the diameter of the structural reinforcing bar S3. When the diameter of the core material 22 is 10 mm or more, the workability of installing the core material 22 can be improved. When the diameter of the core material 22 is not more than the diameter of the structural reinforcing bar S3, it is possible not to affect the above bending characteristics.

[0040] As described above, the tensile detection device 21 according to the second embodiment can obtain the same operational effects as those of the aforementioned tensile detection device 1. Furthermore, in the tensile detection device 21, the core material 22 is made of a material having a yield strength higher than that of the structural reinforcing bar S3. Therefore, since the yield strength of the core material 22 is higher than the yield strength of the structural reinforcing bar S3, the amount of residual strain in the fixing region A can be more reliably made proportional to the tensile force. Accordingly, the past history or the maximum response of the tensile force can be detected with higher accuracy.

[0041] (Third Embodiment) Subsequently, the tensile detection device 31 according to the third embodiment will be described with reference to Fig. 5(a). The tensile detection device 31 is different from the second embodiment in that it includes a core material 32 having a shape different from that of the core material 22. However, the material of the core material 32 may be the same as the material of the core material 22, for example. The core material 32 has an extending portion 33 extending in the direction E in which the tensile force H acts, and a branching portion 34 branching from the extending portion 33 and extending in a direction intersecting the direction E. For example, the extending portion 33 extends along the structural reinforcing bar S3, and the branching portion 34 is a fixing bar branching from the extending portion 33 in the fixing region A.

[0042] The core material 32 is embedded in the concrete S4. The core material 32 has, for example, a plurality of branching portions 34. As an example, the variation in the yield resistance of the branching portions 34 is smaller than the variation in the yield resistance of the concrete structure S. The plurality of branching portions 34 may branch from the extending portion 33 in different directions (radially, for example).

[0043] The core material 32 has a set C of branching portions 34 having the same position in the direction E. The number of branching portions 34 in the set C is, for example, two, but may be one or three or more. Fig. 5(a) shows an example in which the number of branching portions 34 in the set C is two, the core material 32 includes three sets C, and a total of six branching portions 34 are provided.

[0044] For example, assuming that a tensile force H1, a tensile force H2 greater than the tensile force H1, and a tensile force H3 greater than the tensile force H2 each act on the tensile detection device 31, when the tensile force H1 acts, only one branch portion 34 of the set C located on the measuring instrument 13 side (upper side) yields. When a tensile force H2 greater than the tensile force H1 acts, the branch portions 34 of two sets C located on the measuring instrument 13 side (upper side) yield.

[0045] And when a tensile force H3 greater than the tensile force H2 acts, all the branch portions 34 of the set C yield. Therefore, by the detection device 11 detecting the presence or absence of yielding in the branch portion 34, the maximum response of the tensile force H that occurred in the past can be detected. Specifically, the tensile detection device 31 measures the residual strain generated in the core material 32 (branch portion 34) using the detection device 11, and estimates the maximum value of the tensile force acting on the core material 32 from the measured residual strain.

[0046] FIG. 5(b) shows an example in which the material of the branch portion 34 is different from the material of the extending portion 33. As shown in FIG. 5(b), the material and number of the branch portion 34 can be appropriately changed. The material of the extending portion 33 is, for example, carbon fiber reinforced plastic (CFRP: Carbon Fiber Reinforced Plastics), and the branch portion 34 is a stud-shaped steel material.

[0047] The extending portion 33 has, for example, a round bar shape. As an example, the branch portion 34 has a general portion 34b extending from the extending portion 33 and a diameter-expanded portion 34c located on the side opposite to the extending portion 33 of the general portion 34b. FIG. 5(b) shows an example in which the number of branch portions 34 in the set C is 2, the core material 32 includes 4 sets C, and a total of 8 branch portions 34 are provided.

[0048] As shown in FIGS. 5(b), 6(a), 6(b), and 6(c), when the tensile force H1 acts, the residual strain Z11 occurs only in the branch portion 34 (branch portion 34A) of the set C located on the side of the measuring instrument 13. When a tensile force H2 greater than the tensile force H1 acts, the residual strain Z12 occurs in the branch portions 34 (branch portion 34A and branch portion 34B) of the two sets C located on the side of the measuring instrument 13. Then, when a tensile force H3 greater than the tensile force H2 acts, the residual strain Z13 occurs in the branch portions 34 (branch portion 34A, branch portion 34B, and branch portion 34C) of the three sets C located on the side of the measuring instrument 13.

[0049] As described above, in the tensile detection device 31 according to the third embodiment, the core material 32 has an extending portion 33 extending along the structural reinforcing bar S3 and a branch portion 34 branching from the extending portion 33 in the fixing region A. The branch portion 34 yields when the tensile force H on the concrete S4 is equal to or greater than a predetermined value. Therefore, by the detection device 11 detecting the presence or absence of yielding of the branch portion 34, it is possible to easily grasp whether the tensile force H in the fixing region A was equal to or greater than a predetermined value (for example, whether it was equal to or greater than the tensile force H1, whether it was equal to or greater than the tensile force H2, or whether it was equal to or greater than the tensile force H3).

[0050] In addition, since the variation in the yield strength of the branch portion 34 is small, there is an advantage that it is easy to establish a correlation between the applied tensile force H and the maximum strain and the section where the branch portion 34 yields and strain remains in the branch portion 34. When the extending portion 33 is made of CFRP and the branch portion 34 is a stud-shaped steel material, the above advantages become more prominent.

[0051] As described above, various embodiments of the tensile detection device according to the present disclosure have been described. However, the tensile detection device according to the present disclosure is not limited to the foregoing embodiments or various examples, and can be appropriately changed within the scope of the gist described in the claims. That is, the configuration, shape, size, material, number, and arrangement mode of each part of the tensile detection device can be appropriately changed within the scope of the above gist.

[0052] For example, in the foregoing embodiment, an example in which the structural reinforcing member is the structural reinforcing bar 3 has been described. However, the structural reinforcing member is not limited to reinforcing bars. The structural reinforcing member may be, for example, an SC structure, a CFRP structure, or a post-construction anchor or the like. Further, in the foregoing embodiment, an example in which the tensile detection device 1 is embedded in the concrete structure S provided at the base of the pier has been described. However, the tensile detection device is also applicable to concrete structures other than the base of the pier. For example, as shown in FIGS. 7 and 8, the tensile detection device according to the present disclosure may be applied to the joint structure T2 of the steel pipe pile T21 or the joint structure T3 of the SC pile T31. Since these joint structures may be plasticized in terms of seismic behavior and the like, it is important to detect the tensile force with the tensile detection device.

[0053] The joint structure T2 includes a steel pipe pile T21 and a footing T22 located vertically above the steel pipe pile T21. The joint structure T2 includes a plurality of reinforcing bars T23 extending in the vertical direction D1 while being inserted into both the steel pipe pile T21 and the footing T22, and the detection device 11 of the tensile detection device is attached along at least any one of the plurality of reinforcing bars T23.

[0054] Similar to the joint structure T2, the joint structure T3 includes an SC pile T31, a footing T32, and a plurality of reinforcing bars T33 inserted into both the SC pile T31 and the footing T32. Also in the joint structure T3, by attaching the detection device 11 of the tensile detection device to any one of the plurality of reinforcing bars T33, it is possible to detect the tensile force. As described above, an example in which the tensile detection device is applied to the steel pipe pile T21 or the SC pile T31 has been described. However, the tensile detection device may be applied to a steel pipe soil cement pile or a PHC pile.

[0055] As shown in FIG. 9, the tensile detection device according to the present disclosure may be applied to the support T4. As an example, the support T4 is a seismic isolation device. In this case, the support T4 has an upper flange T41, a lower flange T42, and a laminated rubber T43 interposed between the upper flange T41 and the lower flange T42. The support T4 is fixed to the concrete T44 by a plurality of anchor bars T45 embedded in the concrete T44, and the detection device 11 of the tensile detection device is attached along at least any one of the plurality of anchor bars T45. In this case, the behavior of the anchor bar T45 coming out of the concrete T44 can be detected by the detection device 11. Note that the support T4 may be other than a seismic isolation device, and for example, it may be provided as an attachment part of a bridge-fall prevention device.

[0056] As described above, various modifications to which the tensile detection device according to the present disclosure is applied have been described. However, the tensile detection device according to the present disclosure can be further modified. For example, in the above-described embodiment, the detection device 11 which is an optical fiber cable has been described. However, the detection device may be other than an optical fiber cable. For example, the detection device may include a plurality of strain gauges instead of the optical fiber cable. For example, it may be a tensile detection device in which a plurality of strain gauges are attached to a core material and the tensile force is estimated from the measurement results of the plurality of strain gauges.

Description of Reference Numerals

[0057] 1, 21, 31... Tensile detection device, 11... Detection device (optical fiber cable), 12, 22, 32... Core material, 13... Measuring instrument, 33... Extension part, 34, 34A, 34B, 34C... Branch part, 34b... General part, 34c... Diameter-expanded part, A... Fixing area, C... Group, D1... Vertical direction, E... Direction, F... Horizontal seismic force, H, H1, H2, H3... Tensile force, K1... Measuring light, K2... Backscattered light, P... Tip position, S, T1... Concrete structure, S1... Column part, S2... Expansion part, S3... Structural reinforcing bar (structural reinforcement), S4... Concrete, S5... Fixing part, S6... Base part, T2, T3... Joint structure, T4... Support, T21... Steel pipe pile, T22... Footing, T23, T33... Reinforcing bar, T31... SC pile, T32... Footing, T41... Upper flange, T42... Lower flange, T43... Laminated rubber, T44... Concrete, T45... Anchor bar, Z1, Z2, Z11, Z12, Z13... Residual strain.

Claims

1. A tensile detection device embedded in a concrete structure provided with a structural reinforcing material, wherein the concrete structure has a fixing region where a fixing portion of the structural reinforcing material is provided, a detection device embedded in the concrete of the concrete structure, for detecting a residual strain remaining in the fixing region along with a tensile force applied to the concrete, and a core material to which the detection device is fixed, characterized in that it comprises: the concrete structure has a column portion extending in the vertical direction and an extension portion expanding at the lower end of the column portion, the concrete structure includes a plurality of the structural reinforcing materials extending in the vertical direction inside the column portion and the extension portion, and the lower ends of the plurality of the structural reinforcing materials are the fixing region having the fixing portion, the fixing region is provided in the extension portion, the core material extends together with the plurality of the structural reinforcing materials, the core material is made of a material having a yield strength higher than that of the structural reinforcing material, the diameter of the core material is smaller than the diameter of the structural reinforcing material, the detection device extends along the structural reinforcing material, and the detection device measures the distribution of the residual strain of the core material after a tensile force generated in the core material due to a horizontal seismic force applied to the concrete structure acts thereon. Tensile detection device.

2. The detection device is an optical fiber cable fixed to the core material. The tensile detection device according to claim 1.

3. The core material has an extending portion extending along the structural reinforcing material and a branching portion branching from the extending portion in the fixing region, and the branching portion yields when the tensile force applied to the concrete is equal to or greater than a predetermined value. The tensile detection device according to claim 1 or claim 2.

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