How to measure strain in buildings

Abstract

To improve a management quality of soundness of a building in a construction of the existing building.SOLUTION: A distortion measurement method of the present building is configured to: set a measurement object area 30 of a distortion to a building 10 in accordance with a content of a construction; attach an optical fiber 40 to a surface of the measurement object area 30 in a state of close contact, while wiring the optical fiber so that a wiring route parallel with a direction of the distortion expected to occur in the measurement object area 30 is included; connect one end 40a of the optical fiber 40 to a measurement device; detect, by the measurement device, expansion / contraction in a range attached to the measurement object area 30 of the optical fiber 40; and measure an occurrence location and size of the distortion based on the basis of the detection result. Accordingly, the distortion actually occurring in the existing building 10 can be measured in real time, and further the distortion at many locations where the optical fiber 40 is attached to the measurement object area 30 of the building 10 can be measured, which in turn a management quality of soundness of the building 10 can be improved.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a strain measurement method for measuring strain in an existing building during construction work on the building. [Background technology]

[0002] In various construction works for existing buildings, it is necessary to pay as much attention as possible so as not to have unintended effects on the building. As an example, in construction work for replacing seismic isolation devices in concrete structures of existing buildings (see, for example, Patent Document 1), jacks are installed around the seismic isolation devices and the seismic isolation device replacement work is performed with part or the whole of the building jacked up, so management is performed so that unhealthy stress is not input to the building during that time. Conventional methods for such management include a method of setting a management value for the horizontal displacement of the structure between adjacent columns and using AI to manage the changes, and a method of applying a pattern by spraying or the like to a measurement surface where the action of stress is expected to occur, generating a three-dimensional mesh, detecting the deformation of the three-dimensional mesh, and measuring strain, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-084038 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned method using AI, the stress on the concrete is assumed on paper as horizontal displacement = deformation angle, and the control value is set, which differs from the stress actually input to the concrete structure, and proper control was not performed. Also, in the method using a 3D mesh, the measurement surface on which the 3D mesh was generated is monitored with a camera, so the measurement points are limited and control is insufficient. The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to improve the quality of management of the soundness of buildings during construction of existing buildings. [Means for solving the problem]

[0005] (Mode of the invention) The following aspects of the invention are illustrative of the configuration of the present invention, and are described in terms of items to facilitate understanding of the various configurations of the present invention. Each item does not limit the technical scope of the present invention, and the technical scope of the present invention may include any embodiment in which some of the components of each item are replaced or deleted, or other components are added, while taking into account the best mode for carrying out the invention.

[0006] (1) A method for measuring strain in an existing building during construction work, comprising the steps of: setting a strain measurement area in the building according to the content of the construction work; and setting a wiring route parallel to the direction of strain expected to occur in the measurement area. The optical fiber is guided along the surface of the measurement target area. While wiring, The above An optical fiber is attached in close contact with the surface of the measurement target area, one end of the optical fiber is connected to a measurement device, and the measurement device measures the expansion and contraction of the optical fiber in the area where it is attached to the measurement target area. Continuously over the entire range A method for measuring strain in a building (Claim 1) that detects strain and measures the location and magnitude of the strain based on the detection results.

[0007] The method for measuring strain in a building described in this section involves setting a measurement area for measuring strain in an existing building, centering on, for example, a location that is likely to be subjected to load due to the effects of construction, depending on the contents of the construction work on the existing building. Then, taking into consideration the direction and magnitude of the external force applied due to the effects of the construction work, the direction of strain occurring in the measurement area is assumed, and if strain is expected to occur at multiple locations in the measurement area, the direction of strain at each of those locations is assumed. Furthermore, an optical fiber is wired along the surface of the measurement area so that the wiring route is parallel to the assumed direction of strain, and the optical fiber is attached in close contact with the surface of the measurement area.

[0008] A measuring device is then connected to one end of the optical fiber, and the measuring device measures the expansion and contraction of the area of ​​the optical fiber that is attached to the measurement target area. Continuously over the entire range That is, the optical fiber is attached in close contact with the surface of the measurement target area, including a wiring route parallel to the expected direction of strain, so when strain occurs in the measurement target area, it expands and contracts under the influence. Therefore, the measuring device detects the position and magnitude of such expansion and contraction in the optical fiber, and from this detection result, the position and magnitude of the strain occurring in the measurement target area of ​​the building are measured.

[0009] With the above-mentioned configuration, the strain that actually occurs in an existing building is measured in real time, so that the strain caused by unexpected factors that could not be understood by desk calculation alone can also be measured. Furthermore, since the strain is measured over the entire range of the optical fiber attached to the measurement target area of ​​the building, it is measured at positions spaced at intervals of several mm on a line rather than at points, improving the quality of management of the soundness of the building. Moreover, the only construction required for measurement is the attachment of the optical fiber, and the measurement itself is performed by a measuring device, so that the strain can be easily measured without leaving any effect on the building after measurement. This makes it applicable to various existing buildings, such as modern buildings made of concrete, buildings that include environments where electromagnetic fields and fires are strictly prohibited, buildings that do not have drawings and are difficult to estimate on paper, and wooden buildings that are culturally important.

[0010] (2) A method for measuring strain in a building, as set forth in the above (1), comprising: setting a plurality of measurement target areas; attaching a plurality of the optical fibers to the plurality of measurement target areas and connecting them to the measuring device; and simultaneously measuring the plurality of measurement target areas using the measuring device (Claim 2). The method for measuring strain in a building described in this section involves setting multiple measurement target areas in an existing building and attaching multiple optical fibers to these multiple measurement target areas. At this time, one or more optical fibers may be attached to one measurement target area depending on the strain expected to occur in each of the measurement target areas, and one optical fiber may be attached across two or more measurement target areas. Then, one end of each of the multiple optical fibers is connected to a measuring device, and the strains occurring in the multiple measurement target areas are measured simultaneously by the measuring device. As a result, even if strains due to construction are expected to occur at various positions on the building, they can be measured simultaneously by the measuring device, thereby further improving the quality of management of the soundness of the building.

[0011] (3) In the above items (1) and (2), the construction work is work to replace or install a seismic isolation device by jacking up at least a part of the building, and a method for measuring strain in the measurement target area is provided (Claim 3). The method for measuring strain in a building described in this section is applied to construction work in which at least a part of an existing building is jacked up to replace a seismic isolation device, or to retrofit construction work in which a new seismic isolation device is installed. During this construction work, at least when the building is jacked up, strain is measured in a measurement target area set in a location that is expected to be easily subjected to load due to jacking up. As a result, the strain generated in the building during jacking up is measured in real time, so that construction work can be carried out with greater consideration given to safety, not only when the entire building, but even when only a part of the building is jacked up.

[0012] (4) A method for measuring strain in a building according to any one of (1) to (3) above, wherein the measurement target area is made of a concrete component, and the optical fiber is attached to the measurement target area using an adhesive (Claim 4). In the method for measuring strain in buildings described in this section, the measurement target area in which the strain is measured and set according to the contents of the construction is made up of concrete members, and an optical fiber is attached to the measurement target area using an adhesive. This allows the optical fiber to be attached in close contact with the concrete surface of the measurement target area, and changes such as strain occurring in the measurement target area are transmitted to the optical fiber more accurately, improving the strain detection capability. Furthermore, the adhesive makes the attachment work easier, even when the optical fiber is attached to a wide measurement target area or multiple measurement target areas.

[0013] (5) A method for measuring strain in a building according to the above (4), comprising the steps of: applying a pre-coating with the adhesive to the concrete surface of the measurement target area; and then attaching the optical fiber using the adhesive (Claim 5). In the method for measuring strain in a building described in this section, when attaching an optical fiber to a measurement target area made of concrete members, the concrete surface of the measurement target area is pre-coated with an adhesive, and then the optical fiber is attached there using the same adhesive. This increases the adhesion of the optical fiber to the concrete surface of the measurement target area, and prevents the optical fiber from breaking in the unlikely event that cracks or the like occur in the concrete.

[0014] (6) A method for measuring strain in a building according to any one of (1) to (5) above, in which the measuring device detects expansion and contraction of the optical fiber by injecting a tunable laser into the optical fiber and detecting Rayleigh scattered light that occurs within the optical fiber (Claim 6). The strain measurement method for a building described in this section detects the position and magnitude of expansion and contraction occurring in the optical fiber by injecting a tunable laser into the optical fiber from one end of the optical fiber using a measurement device and detecting the Rayleigh scattered light generated in the optical fiber. That is, the wavelength distribution of the Rayleigh scattered light in the optical fiber is determined by the density unevenness and impurities during the manufacture of each optical fiber, so by measuring it in advance, the wavelength distribution of the Rayleigh scattered light in the normal state when no expansion and contraction occurs in the optical fiber is grasped. Then, since the wavelength distribution of the Rayleigh scattered light changes at the point where expansion and contraction occurs in the optical fiber, the position and the degree of change in the wavelength distribution of the Rayleigh scattered light during measurement are detected from the previously grasped wavelength distribution of the Rayleigh scattered light in the normal state, and the expansion and contraction of the optical fiber is detected. This improves the detection accuracy of the expansion and contraction occurring in the optical fiber, in other words, the detection accuracy of the strain occurring in the measurement target area where the optical fiber is attached, and further improves the quality of management of the soundness of the building.

[0015] (7) A method for measuring strain in a building, in accordance with items (1) to (6) above, which sets a control value for the magnitude of strain depending on the material constituting the area to be measured, and monitors whether the measurement result of the magnitude of strain obtained by the measuring device exceeds the control value (Claim 7). The method for measuring strain in buildings described in this section involves setting a control value for the magnitude of strain that serves as a guideline for when an abnormality occurs, depending on the material that constitutes the measurement target area, and monitoring whether the magnitude of strain in the measurement target area measured by the measurement device exceeds the set control value. As a result, if the measurement result of the measurement device exceeds the control value, it is assumed that an abnormality has occurred in the measurement target area, and visual confirmation and measures according to the results are quickly carried out, thereby strengthening the management system for buildings under construction. Effect of the Invention

[0016] Since the present invention has the above-described configuration, it is possible to improve the quality of management of the soundness of buildings during construction of existing buildings. [Brief description of the drawings]

[0017] [Figure 1] 1 is a flow chart showing an example of a procedure of a method for measuring strain in a building according to an embodiment of the present invention. [Diagram 2] These are conceptual images of a building when jacked up, where (a) is an image showing the assumed direction of strain, and (b) is an image showing the optical fiber wiring route. [Diagram 3] The figure shows an image of optical fiber bonding, where (a) is a side view of the optical fiber attachment surface, and (b) is a cross-sectional image perpendicular to the extension direction of the optical fiber. [Figure 4] 1 is a block diagram showing an example of the configuration of a measuring device used in a method for measuring strain in a building according to an embodiment of the present invention. [Diagram 5] 5 is a graph showing an example of a calculation result displayed by the measurement device of FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. Here, detailed descriptions of the same or corresponding parts as those in the prior art will be omitted, and the same or corresponding parts are indicated by the same reference numerals throughout the drawings. The method for measuring strain in a building according to the embodiment of the present invention measures strains occurring in various existing buildings during construction work on those buildings. FIG. 1 shows an example of the procedure of such a method for measuring strain in a building, as an example of application to replacement work of a seismic isolation device on an existing concrete building, and the method for measuring strain in a building according to the embodiment of the present invention will be described below along the flow diagram of FIG. 1. However, the method for measuring strain in a building according to the embodiment of the present invention is not limited to the flow diagram of FIG. 1, and may be a flow in which some of the steps shown in FIG. 1 are deleted, changed, or appropriately added depending on the type of building or the contents of the construction work.

[0019] S10 (Setting of measurement target area): A measurement target area for measuring strain is set in the building according to the contents of the construction work to be performed on the existing building. That is, in this embodiment, as shown in FIG. 2, for example, a measurement target area 30 is set in the existing building 10 made of concrete 32, taking into consideration that the building 10 will be jacked up while the seismic isolation device 22 is replaced. For this reason, multiple (or one) measurement target areas 30 are set according to the scale of the building 10, focusing on areas expected to be easily subjected to load due to jacking up, such as areas near the area to be jacked up, and areas expected to be irregular in shape and to be subjected to stress differently from other areas.

[0020] S20 (Consideration of direction of strain occurrence): Consider the direction of strain that is expected to occur for each of the measurement target areas 30 set in S10 above. For example, Fig. 2(a) shows how the upper structure 12 is jacked up by a jack 20 in order to replace the seismic isolation device 22 installed between the upper structure 12 and the lower structure 14 in an existing building 10, and a measurement target area 30 is set near the jacked-up location of the upper structure 12. In such a measurement target area 30, it is expected that a deflection as indicated by the symbol DL will occur due to the load from the jack 20, indicated by the upward arrow in the figure, and the weight of the upper structure 12, indicated by the downward arrow in the figure. For this reason, at the position of the arrow indicated by the symbol SA, strain due to shear in the vertical direction in the figure indicated by that arrow is assumed, at the position of the arrow indicated by the symbol CA, strain due to compression in the horizontal direction in the figure indicated by that arrow is assumed, and at the position of the arrow indicated by the symbol TA, strain due to tension in the horizontal direction in the figure indicated by that arrow is assumed. Note that for construction other than the replacement work of the seismic isolation device 22, the direction of strain generation can be assumed depending on the direction and position of the external force applied by the construction work.

[0021] S30 (Optical fiber wiring route consideration): Consider the wiring route of the optical fiber 40 to be attached to the measurement target area 30 and used for strain measurement. At this time, consider the wiring route of the optical fiber 40 as shown in FIG. 2(b) so as to include a wiring route parallel to the direction of strain as shown in FIG. 2(a) assumed in S20 above. That is, referring to both FIG. 2(a) and (b), in the vicinity of the arrow SA indicating strain due to shear, set a wiring route along the up-down direction in the figure parallel to the direction of the arrow SA, in the vicinity of the arrow CA indicating strain due to compression, set a wiring route along the left-right direction in the figure parallel to the direction of the arrow CA, and in the vicinity of the arrow TA indicating strain due to tension, set a wiring route along the left-right direction in the figure parallel to the direction of the arrow TA. Note that, depending on the position where the strain is expected to occur and the number of strains, a wiring route in which two or more optical fibers 40 are attached to one measurement target area 30 or a wiring route in which one optical fiber 40 is attached across two or more measurement target areas 30 may be considered.

[0022] S40 (setting of strain control value): A strain control value is set according to the material constituting the measurement target area 30. In the embodiment shown in FIG. 2, since the measurement target area 30 is composed of concrete 32, for example, a strain control value is set at a magnitude that serves as an indication of the occurrence of abnormalities such as cracks in the concrete 32. The strain control value is a positive value for tensile strain and a negative value for compressive strain. The strain control value set here is used to monitor the magnitude of strain occurring in the measurement target area 30 in S120 described later.

[0023] S50 (perform pre-coating): Taking into consideration the wiring route of the optical fiber 40 examined in S30 above, a pre-coating 52 (see FIG. 3(b)) is applied with an adhesive while adjusting the thickness in the area where the optical fiber 40 is to be attached on the surface of the concrete 32 that constitutes the measurement target area 30. The adhesive used for this pre-coating 52 is the same as the adhesive 50 (see FIG. 3(b)) used to adhere the optical fiber 40 in S70 described below. Note that prior to the application of the pre-coating 52, treatments such as exposing the base material of the concrete 32, polishing the surface of the concrete 32 to make it flat, and degreasing the surface of the concrete 32 may be performed. S60 (Optical fiber wiring and temporary fixing): As shown in FIG. 2(b), while wiring the optical fiber 40 according to the wiring route considered in S30 above, the optical fiber 40 is temporarily fixed in the measurement target area 30 on top of the pre-coating 52 applied in S50 above using masking tape or the like.

[0024] S70 (Optical fiber bonding): The optical fiber 40 temporarily fixed in S60 above is bonded to the measurement target area 30 over the pre-coating 52 with an adhesive 50, as shown in Fig. 3(b). The adhesive 50 used for this bonding and the pre-coating 52 is selected to have no effect on the members constituting the measurement target area 30, to follow deformations such as strain in the measurement target area 30, and to be unlikely to change due to other factors. Furthermore, depending on the situation, the optical fiber 40 may be further protected by covering it with vinyl tape, liquid rubber, sponge tape, etc. after bonding with the adhesive 50.

[0025] In this embodiment, as shown in Fig. 2(b) and Fig. 3(a), one end 40a of the optical fiber 40 extends outward without being bonded to the measurement target area 30, the one end 40a is connected to the remote module 46, and the other end 40b is attached to the measurement target area 30 after being appropriately terminated. Furthermore, in Fig. 3(a), the area between the measurement point 42 and the measurement point 44 is shown as the range in which measurement is performed by the optical fiber 40, and the area between the measurement point 42 and the other end 40b is bonded as shown in Fig. 3(b), and the area between the measurement point 42 and the one end 40a is covered with a Teflon (registered trademark) tube or the like, and a part of the Teflon (registered trademark) tube is further covered with a protective tube 48 made of stainless steel or the like. However, the necessity of such a member for protection is optional.

[0026] S80 (connection of measuring device): A measuring device 60 as shown in FIG. 4 is connected to one end 40a of the optical fiber 40 via a remote module 46 in this embodiment. An extension cable 54 is interposed between the remote module 46 and the measuring device 60, so that the measuring device 60 can be installed at any position away from the measurement target area 30. The measuring device 60 in FIG. 4 includes a transceiver 62 that transmits and receives light to and from the optical fiber 40, a calculation unit 64 that performs calculations such as measuring strain according to the light reception results of the transceiver 62, and a display unit 66 that displays the calculation results of the calculation unit 64. The transceiver 62 is connectable to a plurality of optical fibers 40, and transmits and receives light to and from them simultaneously. Such a measuring device 60 is realized by a combination of dedicated hardware including a personal computer and the like, and dedicated software executed thereon.

[0027] S90 (preparation judgment): It is judged whether or not the steps S20 to S80 have been performed for all measurement target regions 30 set in S10. Then, if the steps S20 to S80 have been performed for all measurement target regions 30, the process proceeds to S100, and if there are any measurement target regions 30 for which the steps S20 to S80 have not been performed, the process returns to S20 etc. and performs the unperformed steps for those measurement target regions 30. S100 (start of jacking up): As shown in Fig. 2, in order to replace the seismic isolation device 22, the superstructure 12 of the existing building 10 is gradually raised and jacked up by the jack 20. Note that although only one jack 20 is shown in Figs. 2(a) and (b), the jack 20 is installed in various positions including around each of the multiple seismic isolation devices 22 installed in the building 10, and they all jack up the building 10 at the same time, thereby jacking up the whole or part of the building 10.

[0028] S110 (detection of optical fiber expansion / contraction): When jacking up of the building 10 is started, the measurement device 60 detects expansion / contraction of the optical fibers 40 occurring in each of the measurement target areas 30. Specifically, in this embodiment, a tunable laser is continuously incident from the transmitting / receiving unit 62 to each of the optical fibers 40 connected thereto. The transmitting / receiving unit 62 receives the Rayleigh scattered light returning from each optical fiber 40, and the calculation unit 64 compares the wavelength of the Rayleigh scattered light received from each optical fiber 40 with the wavelength distribution of the Rayleigh scattered light of each optical fiber 40 acquired in advance. From the comparison result, a change in the wavelength distribution of the Rayleigh scattered light indicating that the optical fiber 40 has expanded / contracted is detected, and the position where the expansion / contraction of the optical fiber 40 has occurred and the magnitude of the expansion / contraction are calculated for each of the optical fibers 40 connected to the transmitting / receiving unit 62.

[0029] S120 (strain measurement and monitoring): The measuring device 60 measures the position and magnitude of the strain generated in the measurement target area 30 from the position and magnitude of the expansion and contraction of the optical fiber 40 detected in S110 above. Fig. 5 shows an example of a graph displayed by the display unit 66, in which the magnitude of the expansion and contraction generated in the optical fiber 40 at a certain point in time is taken as the vertical axis and the distance from one end 40a of the optical fiber 40 is taken as the horizontal axis. For example, assuming that the distance along the optical fiber 40 from one end 40a of the optical fiber 40 to the measurement point 42 is 8m, the measurement result of the strain at the measurement point 42 shown in Fig. 3(a) will appear at a distance of 8m in a graph such as that shown in Fig. 5.

[0030] 2(b), by grasping the position of the optical fiber 40 wired to measure each of the shear strain (SA), compressive strain (CA), and tensile strain (TA) in FIG. 2(a) as a distance from one end 40a of the optical fiber 40, the measurement result of each strain will appear at each distance position on a graph such as FIG. 5. In this way, by linking the distance position (distance from one end 40a) of each optical fiber 40 with the wiring route of each optical fiber 40 in the measurement target area 30, the strain generated in the measurement target area 30 can be measured from the measurement result such as FIG. 5.

[0031] Furthermore, in this step S120, the strain control value set in S40 is used to monitor whether or not abnormal strain occurs. As an example, FIG. 5 shows control value lines ML1 and ML2 indicating the respective control values, with the strain control value on the tensile side being +75μ and the strain control value on the compressive side being -250μ, although not limited to these values. When the strain control values ​​are set in this way, monitoring may be performed so that the measured strain value does not exceed the control value line ML1 and does not fall below the control value line ML2. When a strain that exceeds the control value lines ML1 and ML2 is measured, the measuring device 60 may issue a warning by voice or display. It can be seen from the graph in FIG. 5 that the magnitude of the strain is generally within ±25μ in the range from one end 40a of the optical fiber 40 to 20 m, and that no particularly problematic strain occurs. The above step S110 and this step S120 are to be performed continuously at least until jacking up of the building 10 is completed.

[0032] S130 (end of jacking up): When the replacement work of all the seismic isolation devices 22 planned for the construction is completed, the upper structure 12 is gradually lowered and the jacking up of the existing building 10 with the jacks 20 is completed. In this embodiment, the measurement of strain by the measuring device 60 is also completed at the same time, but depending on the situation, the measurement of strain by the measuring device 60 may be continued for any time after the jacking up of the building 10 is completed. With the steps up to this point, the procedure of an example of a method for measuring strain in a building according to an embodiment of the present invention is completed.

[0033] Here, the method for measuring strain on a building according to the embodiment of the present invention is not limited to the configurations shown in Figs. 1 to 5. For example, the measurement target area 30 is not limited to the vicinity of the jack-up point of the building 10, but may be set at any location made of any material. The existing building 10 is not limited to concrete, but may be made of wood or stone. If the measurement target area 30 is made of a material other than concrete, an appropriate mounting means is used that can mount the optical fiber 40 in close contact without affecting the material. Furthermore, the content displayed by the display unit 66 of the measuring device 60 may be various contents showing the calculation results of the calculation unit 64 other than the graph of Fig. 5, and for example, the magnitude of strain at any measurement point may be displayed over time. Also, in the graph of Fig. 5, the horizontal axis of the distance of the optical fiber 40 is not limited to the distance from one end 40a of the optical fiber 40, but may display any distance range from any position.

[0034] According to the embodiment of the present invention having the above configuration, the following effects can be obtained. That is, in the method for measuring strain in a building according to the embodiment of the present invention, as shown in Fig. 2, a measurement target area 30 for measuring strain is set in the existing building 10, centering on a place where a load is likely to be applied due to the influence of the construction, for example, in the existing building 10 according to the contents of the construction work (see S10 in Fig. 1). Then, taking into consideration the direction and magnitude of the external force applied due to the influence of the construction work, the direction of strain occurring in the measurement target area 30 is assumed, and at this time, if strain is assumed to occur at multiple places in the measurement target area 30, the direction of strain at each of those places is assumed (see S20 in Fig. 1). Furthermore, the optical fiber 40 is wired along the surface of the measurement target area 30 so that the wiring route is parallel to the assumed direction of strain occurrence, and the optical fiber 40 is attached in close contact with the surface of the measurement target area 30 (see S60 and S70 in Fig. 1).

[0035] Then, a measuring device 60 such as that shown in Fig. 4 is connected to one end 40a of the optical fiber 40 (see S80 in Fig. 1), and the measuring device 60 detects the expansion and contraction of the optical fiber 40 in the range where it is attached to the measurement target area 30 (see S110 in Fig. 1). That is, the optical fiber 40 includes a wiring route parallel to the expected direction of strain generation and is attached in close contact with the surface of the measurement target area 30, so that when strain occurs in the measurement target area 30, it expands and contracts under the influence of the strain. Therefore, the measuring device 60 detects the position and magnitude of the expansion and contraction that has occurred in the optical fiber 40, and measures the position and magnitude of the strain that has occurred in the measurement target area 30 of the building 10 from the detection result (see S120 in Fig. 1).

[0036] With the above-mentioned configuration, the strain actually occurring in the existing building 10 can be measured in real time, so that the strain occurring due to unexpected factors that could not be understood by desk calculation alone can also be measured. Furthermore, since the strain can be measured in the entire range where the optical fiber 40 is attached to the measurement target area 30 of the building 10, it is possible to measure at positions spaced apart by several mm on a line rather than at points, and the quality of management of the soundness of the building 10 can be improved. Moreover, since the construction performed on the building 10 for measurement is only the attachment of the optical fiber 40, and the measurement itself is performed by the measuring device 60, it is possible to easily measure the strain without leaving any effect on the building 10 after the measurement. This makes it possible to apply the present invention to various existing buildings 10, such as modern buildings such as concrete buildings, buildings that include environments where electromagnetic fields and fires are strictly prohibited, buildings that do not have drawings and are difficult to estimate on paper, and wooden buildings that are culturally important.

[0037] Furthermore, the method for measuring strain in a building according to the embodiment of the present invention involves setting a plurality of measurement target areas 30 in an existing building 10, and attaching a plurality of optical fibers 40 to the plurality of measurement target areas 30. Then, one end 40a of each of the plurality of optical fibers 40 is connected to a measuring device 60, and strains occurring in the plurality of measurement target areas 30 are simultaneously measured by the measuring device 60. As a result, even if strains due to construction are expected to occur at various positions in the building 10, they can be measured simultaneously by the measuring device 60, making it possible to further improve the quality of management of the soundness of the building 10.

[0038] The method for measuring strain in a building according to the embodiment of the present invention is applied to construction work in which at least a part of an existing building 10 is jacked up to replace a seismic isolation device 22, or to retrofit construction work in which a new seismic isolation device 22 is installed, as shown in Fig. 2. During this construction work, at least when the building 10 is jacked up (see S100 and S130 in Fig. 1), strain is measured in a measurement target area 30 set in a location that is assumed to be easily subjected to load due to jacking up. This makes it possible to measure strain occurring in the building 10 during jacking up in real time, so that construction work can be carried out with greater consideration given to safety, not only when the entire building 10 but also when only a part of the building 10 is jacked up.

[0039] Furthermore, in the method for measuring strain in a building according to the embodiment of the present invention, the measurement target area 30, in which the strain set according to the contents of the construction is measured, is made of a member made of concrete 32, and when attaching the optical fiber 40 to the measurement target area 30, an adhesive 50 is used as shown in FIG. 3(b). This allows the optical fiber 40 to be attached in close contact with the surface of the concrete 32 in the measurement target area 30, and changes such as strain occurring in the measurement target area 30 can be transmitted to the optical fiber 40 more accurately, thereby improving the strain detection ability. Furthermore, even when the optical fiber 40 is attached to a wide measurement target area 30 or multiple measurement target areas 30, the adhesive 50 makes it easy to perform the attachment work.

[0040] Furthermore, in the method for measuring strain in a building according to the embodiment of the present invention, when attaching the optical fiber 40 to the measurement target area 30 composed of a member made of concrete 32, a pre-coating 52 with an adhesive 50 is applied to the surface of the concrete 32 in the measurement target area 30 (see S50 in FIG. 1), and then the optical fiber 40 is attached thereto using the same adhesive 50. This makes it possible to increase the adhesion of the optical fiber 40 to the surface of the concrete 32 in the measurement target area 30, and also makes it possible to prevent the optical fiber 40 from breaking in the unlikely event that a crack or the like occurs in the concrete 32.

[0041] Furthermore, referring to Figs. 2 and 4, the strain measurement method for a building according to the embodiment of the present invention detects the position and magnitude of the expansion and contraction generated in the optical fiber 40 by using a measurement device 60 to input a tunable laser into the optical fiber 40 from one end 40a of the optical fiber 40 and detecting the Rayleigh scattered light generated in the optical fiber 40. That is, the wavelength distribution of the Rayleigh scattered light in the optical fiber 40 is determined by the density unevenness and impurities at the time of manufacturing each optical fiber 40, so by measuring it in advance, the wavelength distribution of the Rayleigh scattered light in the normal state when no expansion or contraction occurs in the optical fiber 40 is grasped. Then, since the wavelength distribution of the Rayleigh scattered light changes at the point where the expansion or contraction occurs in the optical fiber 40, the position and the degree of change in the wavelength distribution of the Rayleigh scattered light during measurement are detected from the previously grasped wavelength distribution of the Rayleigh scattered light in the normal state, and the expansion and contraction of the optical fiber 40 is detected. This makes it possible to improve the detection accuracy of the expansion and contraction generated in the optical fiber 40, in other words, the detection accuracy of the strain generated in the measurement target area 30 to which the optical fiber 40 is attached, and therefore it becomes possible to further improve the management quality of the soundness of the building 10.

[0042] In addition, the method for measuring strain in a building according to the embodiment of the present invention sets a control value for the magnitude of strain that serves as a guideline for when an abnormality occurs, depending on the material that constitutes the measurement target area 30 (see S40 in FIG. 1), and monitors whether the magnitude of strain in the measurement target area 30 measured by the measuring device 60 exceeds the set control value using control value lines ML1 and ML2, for example, as shown in FIG. 5 (see S120 in FIG. 1). As a result, when the measurement result of the measuring device 60 exceeds the control value, it is assumed that an abnormality has occurred in the measurement target area 30, and visual confirmation and measures according to the result can be quickly carried out, thereby strengthening the management system for the building 10 under construction. [Explanation of symbols]

[0043] 10: existing building, 22: seismic isolation device, 30: measurement target area, 32: concrete, 40: optical fiber, 40a: one end, 50: adhesive, 52: pre-coating, 60: measurement device

Claims

1. A method for measuring strain in an existing building during construction work on the building, comprising: A region for measuring strain is set in the building according to the content of the construction work; wiring an optical fiber along a surface of the measurement target area so as to include a wiring route parallel to a direction of strain expected to occur in the measurement target area, and attaching the optical fiber in close contact with the surface of the measurement target area; Connecting one end of the optical fiber to a measurement device; A method for measuring strain in a building, characterized in that the measuring device continuously detects the expansion and contraction over the entire range of the area in which the optical fiber is attached to the measurement target area, and measures the location and magnitude of the strain based on the detection results.

2. The method for measuring strain in a building as described in claim 1, characterized in that a plurality of measurement target areas are set, a plurality of the optical fibers are attached to the plurality of measurement target areas and connected to the measuring device, and the plurality of measurement target areas are simultaneously measured by the measuring device.

3. The construction work is a work to replace or install a seismic isolation device by jacking up at least a part of the building, 3. The method for measuring strain in a building according to claim 1, further comprising the step of measuring the strain in the measurement target area at least when the building is jacked up.

4. the measurement target area is made of a concrete member, 4. The method for measuring strain in a building according to claim 1, wherein the optical fiber is attached to the measurement target area using an adhesive.

5. 5. The method for measuring strain in a building according to claim 4, further comprising the step of: applying a pre-coating with the adhesive to the concrete surface in the measurement target area; and then attaching the optical fiber using the adhesive.

6. A method for measuring strain in a building as described in any one of claims 1 to 5, characterized in that the measuring device detects the expansion and contraction of the optical fiber by injecting a tunable laser into the optical fiber and detecting Rayleigh scattered light that occurs within the optical fiber.

7. A method for measuring strain in a building described in any one of claims 1 to 6, characterized in that a control value for the magnitude of strain is set according to the material that constitutes the measurement target area, and it is monitored whether the measurement result of the magnitude of strain measured by the measuring device exceeds the control value.

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