A kind of wood ancient building bearing structure's fiber grating load vibration monitoring device

Abstract

This invention belongs to the field of monitoring technology for the load-bearing structure of ancient wooden buildings, and solves the technical problems existing in the current field of fiber optic grating sensing, such as the single physical quantity monitored for the load-bearing structure of ancient wooden buildings, small measurement range, inability to change the measurement range, high false alarm rate, and cross-sensitivity to temperature and strain. It provides a fiber optic grating load vibration monitoring device for the load-bearing structure of ancient wooden buildings. The adsorption component is adsorbed onto the bottom of the load-bearing structure of the ancient wooden building used for monitoring. When the load-bearing structure of the ancient wooden building is subjected to external pressure or vibration, the corresponding load strain grating or vibration grating undergoes corresponding strain, and the wavelength signal of the returned light from the grating changes. The returned light signal enters the fiber optic grating demodulator through optical fiber. The fiber optic grating demodulator demodulates the strain parameter through the wavelength change and converts it into a load or vibration signal on the host computer. This invention can realize simultaneous monitoring of multiple directions, multiple points, and multiple physical quantities of the load-bearing structure of ancient buildings.

Description

Technical Field

[0001] This invention belongs to the field of monitoring technology for load-bearing structures of ancient wooden buildings, and specifically relates to a fiber optic grating load vibration monitoring device for load-bearing structures of ancient wooden buildings. Background Technology

[0002] Due to structural aging, human damage, and other reasons, the structural health of ancient wooden buildings is currently a cause for concern. Therefore, health monitoring of the load-bearing structures of ancient wooden buildings is particularly important. Existing methods for monitoring the health of load-bearing structures of ancient wooden buildings mainly rely on electrical methods. These methods utilize electronic sensors deployed in load monitoring systems to monitor the health of the load-bearing structures. However, this method has several drawbacks: Firstly, it does not consider the impact of equipment aging and external environmental factors on the electronic sensors. Furthermore, electronic sensors are susceptible to electromagnetic interference, have limited usability in humid and magnetic field environments, and may even cause irreversible damage to the wooden structure under extreme weather or special circumstances. Secondly, due to the unique nature of ancient wooden buildings, it is difficult to frequently update the relevant equipment to avoid damaging the structures. This causes the accuracy of the electronic sensors to gradually decrease over time, potentially leading to erroneous judgments.

[0003] In recent years, fiber Bragg grating (FBG) sensing technology has been widely used due to its small size, light weight, low loss, integrated sensing capabilities, and resistance to electromagnetic interference. Furthermore, its sensitivity to various physical quantities such as temperature and strain allows for the measurement of multiple physical parameters in different situations based on certain mathematical principles. Compared to commonly used electrical measurement methods, FBG sensors, due to their passive nature, avoid safety hazards caused by circuit failures or overheating, enabling all-weather, all-round, and large-scale real-time online monitoring, making them more suitable for the actual monitoring of the load-bearing structures of wooden ancient buildings. However, current FBG sensing technology suffers from several technical limitations, including the ability to monitor only a single physical quantity for the load-bearing structures of wooden ancient buildings, a small measurement range, inability to change the measurement range, a high false alarm rate, and cross-sensitivity to temperature and strain. Summary of the Invention

[0004] In order to solve at least one of the above-mentioned technical problems in the prior art, the present invention provides a fiber optic grating load vibration monitoring device for the load-bearing structure of wooden ancient buildings.

[0005] This invention is achieved using the following technical solution: a fiber optic grating load vibration monitoring device for the load-bearing structure of a wooden ancient building, comprising a metal sheet, a load measuring unit, a vibration sensing unit, an adsorption component, a fiber optic grating demodulator, and a host computer; the metal sheet includes a transverse sheet and a longitudinal sheet, which are located on the same plane and connected vertically at their ends; the upper and lower surfaces of the metal sheet are symmetrically provided with grooves for placing optical fibers and four load measuring units; two load measuring units on the upper and lower surfaces of the transverse sheet are symmetrically arranged and used to monitor the transverse pressure on the load-bearing structure; two load measuring units on the upper and lower surfaces of the longitudinal sheet... The system is symmetrically arranged and used to monitor the longitudinal pressure on the load-bearing structure. The load measurement unit includes an elastic element, a strain gauge for load measurement, and two range adjustment units symmetrically arranged on both sides of the elastic element. The strain gauge for load measurement is etched onto an optical fiber and attached to the elastic element. The range adjustment units are used to adjust the test range of the load measurement unit. A square through-hole is cut into the surface of a metal sheet to house two vibration sensing units. The vibration sensing unit at the transverse end of the sheet monitors the transverse vibration of the load-bearing structure, and the vibration sensing unit at the longitudinal end monitors the longitudinal vibration of the load-bearing structure. The vibration sensing unit includes a strain gauge for vibration measurement. The structure consists of a grating, a vibrating cantilever beam, and a small mass ball. The first ends of the two elastic materials of the vibrating cantilever beam are connected at an acute angle, with the small mass ball fixed at the apex of the included angle. The second ends of the two elastic materials of the vibrating cantilever beam are fixed at the two apex corners of a square through-hole. A vibration strain grating is etched onto an optical fiber, with one end connected to the small mass ball. The optical fiber is laid starting from the upper surface of a transverse thin plate, passing sequentially through the load measurement unit and vibration sensing unit on the upper surface of the transverse thin plate, the vibration sensing unit and load measurement unit on the upper surface of the longitudinal thin plate, and then leading from the hole at the top of the longitudinal thin plate to the lower surface of the longitudinal thin plate, and then through the load measurement unit on the lower surface of the longitudinal thin plate... The load measurement unit on the lower surface of the transverse thin sheet is finally bonded to the lower surface of the longitudinal thin sheet; the adsorption component is fixed on the upper surface of the metal thin sheet and adsorbed onto the bottom of the monitored wooden ancient building's load-bearing structure; the optical fiber with a grating is connected to the host computer through a fiber optic grating demodulator. When the wooden ancient building's load-bearing structure is subjected to external pressure or vibration, the corresponding load strain grating or vibration strain grating will undergo corresponding strain, and the wavelength signal of the grating's return light will change. The return light signal enters the fiber optic grating demodulator through the optical fiber, and the fiber optic grating demodulator demodulates the strain parameters through the wavelength change and converts them into load or vibration signals on the host computer.

[0006] Preferably, the range adjustment unit includes a pull rod, a movable fixture, a metal baffle, a lightweight spring, and a slider. The groove portion corresponding to the load measurement unit is an I-shaped groove. The metal baffle is overlapped and fixedly connected to the wide end of the I-shaped groove near the strain gauge for load measurement. The movable fixture is fixedly connected to the end of the metal baffle away from the strain gauge for load measurement. The movable fixture is nested and engaged with the pull rod. The pull rod passes through the metal baffle and is connected to the elastic element through the lightweight spring and the slider. By changing the relative position of the pull rod and the movable fixture, the test range of the load measurement unit is adjusted.

[0007] Preferably, the portion of the pull rod located in the I-shaped groove has multiple slots; the movable tool has a Z-shaped structure, including a straight arm, a folding arm, and a pivot. The straight arm is fixed to a metal baffle with bolts, and the folding arm is rotatably connected to the straight arm via the pivot. The folding arm can extend into or rotate out of one of the multiple slots to adjust the position of the pull rod. The two movable tools are symmetrically arranged on both sides of the pull rod.

[0008] Preferably, the strain gratings for the load at the transverse sheet are arranged along the length of the transverse sheet, and the strain gratings for the vibration at the transverse sheet are arranged along the width of the transverse sheet; the strain gratings for the load at the longitudinal sheet are arranged along the length of the longitudinal sheet, and the strain gratings for the vibration at the longitudinal sheet are arranged along the width of the longitudinal sheet.

[0009] Preferably, taking the connection between the transverse and longitudinal thin plates as the starting point, the two metal baffles in the load measuring unit are located at 1 / 3 and 2 / 3 of the length of the transverse or longitudinal thin plate, respectively, and the hole at the top of the longitudinal thin plate is located at 3 / 4 of the length of the longitudinal thin plate.

[0010] Preferably, the square through hole for accommodating the vibration sensing unit is located at 1 / 4 of the length of the transverse or longitudinal sheet, and the vibration sensing unit is suspended in the square through hole and is in the same plane as the metal sheet.

[0011] Preferably, the adsorption assembly includes a vacuum suction cup and a suction cup base. The suction cup base is fixed to the upper surface of the metal sheet by lightweight bolts and nuts, and the vacuum suction cup is adsorbed onto the bottom of the wooden ancient building's load-bearing structure.

[0012] Preferably, the adsorption components are three in number, and are respectively fixed at the junction of the transverse and longitudinal sheets of the metal sheet, at the end of the transverse sheet away from the longitudinal sheet, and at the end of the longitudinal sheet away from the transverse sheet.

[0013] Preferably, both the load strain grating and the vibration strain grating are Bragg gratings, and both are provided with a grating protective shell on their outer sides.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] This invention utilizes a single optical fiber etched with multiple strain gratings to simultaneously monitor strain in both the transverse and longitudinal directions, resulting in more accurate results. Furthermore, it incorporates vibration information that could potentially damage the load-bearing structure of ancient buildings into the monitoring scope, enabling simultaneous monitoring of multiple directions, points, and physical quantities within the load-bearing structure of ancient buildings. By symmetrically attaching strain gratings to the upper and lower surfaces of a thin metal sheet and employing a differential algorithm, this invention achieves temperature self-compensation, making it less susceptible to environmental factors and more accurate compared to existing technologies. The range of the fiber grating can be adjusted by adjusting the pull rod, and the device is mounted on the bottom of the load-bearing structure using a suction cup mounting structure, without damaging the structure of the ancient building itself. This invention is suitable for monitoring various load-bearing structures of ancient buildings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the range adjustment unit of the present invention (first direction);

[0019] Figure 3 This is a schematic diagram of the range adjustment unit of the present invention (second direction);

[0020] Figure 4 This is a structural diagram of the temperature self-compensating grating of the present invention;

[0021] Figure 5 This is a schematic diagram of the adsorption component structure of the device of the present invention;

[0022] Figure 6 This is a schematic diagram of the detection system of the present invention.

[0023] In the diagram: 1-Transverse sheet; 2-Vertical sheet; 3-Fiber optic cable; 4-Elastic element; 5-Strain grating for load; 6-Strain grating for vibration; 7-Vibrating cantilever beam; 8-Small ball; 9-Hole; 10-Fiber grating demodulator; 11-Host computer; 12-Pull rod; 12.1-Multi-position slot; 13-Moving fixture; 13.1-Straight arm of the moving fixture; 13.2-Folding arm of the moving fixture; 13.3-Rotating shaft of the moving fixture; 14-Metal baffle; 15-Lightweight spring; 16-Slider; 17-Vacuum suction cup; 18-Suction cup base; 19-Grate protective shell. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should fall within the scope of the technical content disclosed in the present invention. It should be noted that in this specification, relational terms such as "first" and "second" are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0026] This invention provides an embodiment:

[0027] like Figures 1 to 6As shown, a fiber optic grating load vibration monitoring device for the load-bearing structure of a wooden ancient building includes a metal sheet, a load measurement unit, a vibration sensing unit, an adsorption component, a fiber optic grating demodulator 10, and a host computer 11. The metal sheet includes a transverse sheet 1 and a longitudinal sheet 2, which are located on the same plane and connected vertically at their ends. The upper and lower surfaces of the metal sheet are symmetrically provided with grooves for placing optical fibers 3 and four load measurement units. Two load measurement units on the upper and lower surfaces of the transverse sheet 1 are symmetrically arranged and used to monitor the transverse pressure on the load-bearing structure. Two load measurement units on the upper and lower surfaces of the longitudinal sheet 2 are symmetrically arranged and used to monitor the longitudinal pressure on the load-bearing structure. The load measurement unit includes an elastic element 4, a load strain grating 5, and two range adjustment units symmetrically arranged on both sides of the elastic element 4. The load strain grating 5 is engraved on the optical fiber 3 and pasted on the elastic element 4, and undergoes tensile and compressive deformation as the elastic element 4 deforms. The range adjustment units are used to adjust the test range of the load measurement unit.

[0028] The range adjustment unit includes a pull rod 12, a movable fixture 13, a metal baffle 14, a light spring 15, and a slider 16. The groove corresponding to the load measurement unit is an I-shaped groove. The metal baffle 14 is overlapped and fixed to the wide end of the I-shaped groove near the load strain gauge 5. The movable fixture 13 is fixed to the end of the metal baffle 14 away from the load strain gauge 5. The movable fixture 13 is nested and engaged on the pull rod 12. The pull rod 12 passes through the metal baffle 14 and is connected to the elastic element 4 through the light spring 15 and the slider 16. By changing the relative position of the pull rod 12 and the movable fixture 13, the pre-tension of the load strain gauge 5 is adjusted, thereby adjusting the test range of the load measurement unit of this device.

[0029] The portion of the pull rod 12 located within the I-shaped slot has multiple slots 12.1. The movable fixture 13 has a Z-shaped structure, including a straight arm 13.1, a folding arm 13.2, and a pivot 13.3. The straight arm 13.1 is bolted to the metal baffle 14. The folding arm 13.2 is rotatably connected to the straight arm 13.1 via the pivot 13.3. The folding arm 13.2 can extend into or rotate out of one of the slots 12.1 to adjust the position of the pull rod 12. The two movable fixtures 13 are symmetrically arranged on both sides of the pull rod 12. The test range of the load measurement unit of this device can be adjusted according to the site conditions, thereby improving the applicability and operability of the device.

[0030] The surface of the metal sheet has square through holes for placing two vibration sensing units. The vibration sensing unit at the transverse sheet 1 is used to monitor the transverse vibration of the load-bearing structure, and the vibration sensing unit at the longitudinal sheet 2 is used to monitor the longitudinal vibration of the load-bearing structure. The vibration sensing unit includes a vibration strain grating 6, a vibration cantilever beam 7, and a mass ball 8. The first ends of the two elastic materials of the vibration cantilever beam 7 are connected at an acute angle, and the mass ball 8 is fixed at the apex of the included angle. The second ends of the two elastic materials of the vibration cantilever beam 7 are respectively fixed at the two apex corners of the square through hole. The vibration strain grating 6 is engraved on the optical fiber 3 and one end is connected to the mass ball 8.

[0031] The optical fiber 3 is laid from the upper surface of the transverse thin plate 1, and sequentially passes through the load measurement unit and vibration sensing unit on the upper surface of the transverse thin plate 1, the vibration sensing unit and load measurement unit on the upper surface of the longitudinal thin plate 2, and is led from the hole 9 at the top of the longitudinal thin plate 2 to the lower surface of the longitudinal thin plate 2. Then it passes through the load measurement unit on the lower surface of the longitudinal thin plate 2 and the load measurement unit on the lower surface of the transverse thin plate 1, and is finally bonded to the lower surface of the longitudinal thin plate 2. The optical fiber 3 with grating is connected to the host computer 11 through the fiber optic grating demodulator 10.

[0032] The adsorption components are fixed to the upper surface of the metal sheet and adsorbed onto the bottom of the wooden ancient building's load-bearing structure being monitored. The adsorption components include a vacuum suction cup 17 and a suction cup base 18. The suction cup base 18 is fixed to the upper surface of the metal sheet by lightweight bolts and nuts, and the vacuum suction cup 17 is adsorbed onto the bottom of the wooden ancient building's load-bearing structure. There are three adsorption components, which are respectively fixed at the connection between the transverse sheet 1 and the longitudinal sheet 2 of the metal sheet, at the end of the transverse sheet 1 away from the longitudinal sheet 2, and at the end of the longitudinal sheet 2 away from the transverse sheet 1.

[0033] In this embodiment, the load at the transverse sheet 1 is represented by a strain grating 5 arranged along the length of the transverse sheet 1, and the vibration at the transverse sheet 1 is represented by a strain grating 6 arranged along the width of the transverse sheet 1; the load at the longitudinal sheet 2 is represented by a strain grating 5 arranged along the length of the longitudinal sheet 2, and the vibration at the longitudinal sheet 2 is represented by a strain grating 6 arranged along the width of the longitudinal sheet 2.

[0034] Starting from the junction of the transverse sheet 1 and the longitudinal sheet 2, the two metal baffles 14 in the load measurement unit are located at 1 / 3 and 2 / 3 of the length of the transverse sheet 1 or the longitudinal sheet 2, respectively. The hole 9 on the upper part of the longitudinal sheet 2 is located at 3 / 4 of the length of the longitudinal sheet 2. The square through hole for accommodating the vibration sensing unit is located at 1 / 4 of the length of the transverse sheet 1 or the longitudinal sheet 2. The vibration sensing unit is suspended in the square through hole and is in the same plane as the metal sheet. Both the load strain grating 5 and the vibration strain grating 6 are Bragg gratings, and both are equipped with a grating protective shell 19 on their outer sides.

[0035] The specific working method and principle of this device are as follows:

[0036] The device of this invention is adsorbed onto the bottom of the load-bearing structure of the wooden ancient building using an adsorption component. The load vibration monitoring device of this invention is connected to one end of a fiber optic demodulator 10 via an optical fiber 3 with an etched grating, and the other end of the fiber optic demodulator 10 is connected to a host computer 11. The fiber optic demodulator 10 is an integrated module, which internally includes a scanning laser, a photoelectric converter, a 1*4 splitter, and a 1*2 coupler. The light emitted by the fiber optic demodulator enters the grating-etched optical fiber 3 and passes sequentially through the load strain grating 5 and the vibration strain grating 6 on the upper surface of the transverse thin plate 1, the vibration strain grating 6 and the load strain grating 5 on the upper surface of the longitudinal thin plate 2, and then through the load strain grating 5 on the lower surface of the longitudinal thin plate 2 and the load strain grating 5 on the lower surface of the transverse thin plate 1.

[0037] According to the principle of fiber Bragg gratings: when the light emitted by the fiber Bragg grating demodulator 10 passes through the Bragg grating, light with a wavelength different from the center wavelength of the Bragg grating continues to propagate along its original direction without reflection, while light with the same wavelength as the center wavelength of the Bragg grating is reflected by the Bragg grating and returns along the original path to the fiber Bragg grating demodulator 10 for demodulation, further restoring the information of the physical quantity to be measured. The fiber Bragg grating demodulator 10 transmits the demodulated data to the host computer 11, and displays the load information and vibration information of the bearing structure on the host computer 11 for relevant personnel to view.

[0038] When the load-bearing structure of a wooden ancient building is subjected to external pressure, the external pressure is applied to the load measuring unit on the metal sheet through the load-bearing structure. Both the two load strain gratings 5 ​​placed on the longitudinal sheet 2 and the two load strain gratings 5 ​​placed on the transverse sheet 1 undergo strain. The wavelength signal of the returned light from the strain gratings changes accordingly. The returned light signal enters the fiber optic demodulator 10 through the grating-etched optical fiber 3. The fiber optic demodulator 10 demodulates the strain parameters based on the wavelength change and converts them into corresponding load information on the host computer 11. The transverse and longitudinal pressure values ​​are displayed on the host computer. By observing the strain information distributed at various points on the surface of the load-bearing structure, the operator can determine the load value on the load-bearing structure. The operator can set a strain threshold on the host computer 11. When a value exceeds the set threshold, the host computer 11 issues an alarm, reminding the operator to take timely countermeasures. Since the center wavelength of the Bragg fiber optic grating is affected by both temperature and strain, there is a problem of temperature-strain cross-sensitivity. This invention achieves temperature self-compensation by attaching strain gratings symmetrically to the upper and lower surfaces of the metal sheet and using a differential algorithm. The method for achieving temperature self-compensation is as follows:

[0039] In the load measurement unit, the center wavelengths of the strain gratings located at symmetrical positions on the upper and lower surfaces of the metal sheet should be consistent. That is, the center wavelengths of the two loads on the longitudinal sheet 2 and the two loads on the transverse sheet 1 should be consistent. The principle of temperature self-compensation will be explained below using the load measurement unit of the transverse sheet 1 as an example.

[0040] When the transverse sheet 1 is subjected to external pressure, the rate of change of the two loads on the transverse sheet 1 using the center wavelength of the strain grating 5 is shown in formulas (1) and (2):

[0041]

[0042]

[0043] In the formula, λ A , λ B These are the center wavelengths of the strain gratings used to measure the two loads on the transverse thin sheet; Δλ A , Δλ B These represent the changes in the center wavelength of the strain grating for the two loads on the transverse thin sheet, respectively; ε A ε B The strain values ​​ΔT represent the strain measured by strain gratings for two loads on the transverse thin sheet. A ΔT B These represent the temperature changes measured by strain gratings for two loads on the transverse thin sheet; α is the thermal expansion coefficient of the fiber grating; ζ is the thermo-optic coefficient of the fiber grating; and P... eThe optical elasticity coefficient of the fiber grating is given. Since the device is under the same temperature, ΔT is... A =ΔT B Furthermore, the center wavelengths of the two strain gratings are the same, and the measured strains are equal in magnitude and opposite in direction, i.e., λ A =λ B , ε A =-ε B Subtracting formulas (1) and (2) yields: It can be seen that the strain measured by the strain grating at this time is not related to the temperature change, but only to the elastic coefficient of the fiber grating and the wavelength change rate of the two gratings. Therefore, this structure eliminates the problem of temperature strain cross-sensitivity when the strain grating measures strain.

[0044] When the load-bearing structure of the wooden ancient building is subjected to vibration, the mass ball 8 on the longitudinal thin plate 2 drives the vibrating cantilever beam 7 to vibrate. The vibration strain grating 6 connected to the mass ball 8 will undergo corresponding strain, and the wavelength signal of the light returned by the grating will change accordingly. The returned light signal enters the fiber optic demodulator 10 through the fiber optic cable 3 with the grating etched on it. The fiber optic demodulator 10 demodulates the vibration parameters by measuring the wavelength change and converts them into vibration signals on the host computer 11. The working principle of the transverse thin plate 1 is the same as described above. The staff can observe the vibration signals in each direction and thereby obtain the vibration value of the load-bearing structure. The staff can set a strain threshold on the host computer. When a value exceeds the set threshold, the staff will be alerted to take timely countermeasures.

[0045] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A fiber optic grating load vibration monitoring device for the load-bearing structure of a wooden ancient building, characterized in that: It includes a metal sheet, a load measurement unit, a vibration sensing unit, an adsorption assembly, a fiber optic demodulator (10), and a host computer (11). The metal sheet includes a transverse sheet (1) and a longitudinal sheet (2), which are located on the same plane and connected vertically at their ends. The upper and lower surfaces of the metal sheet are symmetrically provided with grooves for placing optical fibers (3) and four load measuring units. Two load measuring units on the upper and lower surfaces of the transverse sheet (1) are symmetrically arranged and used to monitor the transverse pressure on the load-bearing structure. Two load measuring units on the upper and lower surfaces of the longitudinal sheet (2) are symmetrically arranged and used to monitor the longitudinal pressure on the load-bearing structure. The load measuring unit includes an elastic element (4). The load is measured by a strain gauge (5) and two range adjustment units symmetrically arranged on both sides of the elastic element (4). The strain gauge (5) is engraved on the optical fiber (3) and attached to the elastic element (4). The range adjustment units are used to adjust the test range of the load measurement unit. The range adjustment unit includes a pull rod (12), a movable tool (13), a metal baffle (14), a light spring (15), and a slider (16). The groove corresponding to the load measurement unit is an I-shaped groove. The metal baffle (14) is overlapped and fixed to the I-shaped groove near the strain gauge (5). At the wide slot end, the movable fixture (13) is fixed to the end of the metal baffle (14) away from the strain gauge (5) for load application. The movable fixture (13) is nested and engaged on the pull rod (12). The pull rod (12) passes through the metal baffle (14) and is connected to the elastic element (4) through a light spring (15) and a slider (16). The test range of the load measuring unit is adjusted by changing the relative position of the pull rod (12) and the movable fixture (13). The part of the pull rod (12) located in the wide slot of the I-shaped groove has multiple slots (12.1). The movable fixture (13) is Z-shaped. The structure includes a straight arm (13.1), a folding arm (13.2), and a pivot (13.3). The straight arm (13.1) is fixed to the metal baffle (14) by bolts. The folding arm (13.2) is rotatably connected to the straight arm (13.1) via the pivot (13.3). The folding arm (13.2) can extend into or rotate out of one of the slots of the multi-position slot (12.1) to adjust the position of the pull rod (12). Two movable parts (13) are symmetrically arranged on both sides of the pull rod (12). The surface of the metal sheet has square through holes for placing two vibration sensing units. The vibration sensing unit at the transverse sheet (1) is used to monitor the transverse vibration of the load-bearing structure, and the vibration sensing unit at the longitudinal sheet (2) is used to monitor the longitudinal vibration of the load-bearing structure. The vibration sensing unit includes a vibration strain grating (6), a vibration cantilever beam (7), and a mass ball (8). The first ends of the two elastic materials of the vibration cantilever beam (7) are connected at an acute angle, and the mass ball (8) is fixed at the apex of the included angle. The second ends of the two elastic materials of the vibration cantilever beam (7) are respectively fixed at the two apex corners of the square through hole. The vibration strain grating (6) is engraved on the optical fiber (3) and one end is connected to the mass ball (8). The optical fiber (3) is laid from the upper surface of the transverse sheet (1), and passes through the load measurement unit and vibration sensing unit on the upper surface of the transverse sheet (1), the vibration sensing unit and load measurement unit on the upper surface of the longitudinal sheet (2), and is led from the hole (9) at the top of the longitudinal sheet (2) to the lower surface of the longitudinal sheet (2), and then through the load measurement unit on the lower surface of the longitudinal sheet (2) and the load measurement unit on the lower surface of the transverse sheet (1), and finally bonded to the lower surface of the longitudinal sheet (2); the load at the transverse sheet (1) is arranged by strain grating (5) along the length direction of the transverse sheet (1), and the vibration at the transverse sheet (1) is arranged by strain grating (6) along the width direction of the transverse sheet (1); the load at the longitudinal sheet (2) is arranged by strain grating (5) along the length direction of the longitudinal sheet (2), and the vibration at the longitudinal sheet (2) is arranged by strain grating (6) along the width direction of the longitudinal sheet (2); The adsorption component is fixed on the upper surface of the metal sheet and adsorbed on the bottom of the wooden ancient building's load-bearing structure being monitored. The optical fiber (3) with a grating is connected to the host computer (11) through the fiber optic grating demodulator (10). When the wooden ancient building's load-bearing structure is subjected to external pressure or vibration, the corresponding load strain grating (5) or vibration strain grating (6) will undergo corresponding strain. The wavelength signal of the grating's return light changes. The return light signal enters the fiber optic grating demodulator (10) through the optical fiber (3). The fiber optic grating demodulator (10) demodulates the strain parameters through the wavelength change and converts them into load or vibration signals on the host computer (11).

2. The fiber optic grating load vibration monitoring device for the load-bearing structure of a wooden ancient building according to claim 1, characterized in that: Starting from the connection point of the transverse sheet (1) and the longitudinal sheet (2), the two metal baffles (14) in the load measurement unit are located at 1 / 3 and 2 / 3 of the length of the transverse sheet (1) or the longitudinal sheet (2), respectively, and the hole (9) on the upper part of the longitudinal sheet (2) is located at 3 / 4 of the length of the longitudinal sheet (2).

3. The fiber optic grating load vibration monitoring device for the load-bearing structure of a wooden ancient building according to claim 2, characterized in that: The square through hole for accommodating the vibration sensing unit is located at 1 / 4 of the length of the transverse sheet (1) or longitudinal sheet (2). The vibration sensing unit is suspended in the square through hole and is in the same plane as the metal sheet.

4. The fiber optic grating load vibration monitoring device for the load-bearing structure of a wooden ancient building according to claim 3, characterized in that: The adsorption assembly includes a vacuum suction cup (17) and a suction cup base (18). The suction cup base (18) is fixed to the upper surface of the metal sheet by light bolts and nuts, and the vacuum suction cup (17) is adsorbed onto the bottom of the wooden ancient building's load-bearing structure.

5. The fiber optic grating load vibration monitoring device for the load-bearing structure of a wooden ancient building according to claim 4, characterized in that: The adsorption components are three in number, and are respectively fixed at the connection between the transverse sheet (1) and the longitudinal sheet (2) of the metal sheet, at the end of the transverse sheet (1) away from the longitudinal sheet (2), and at the end of the longitudinal sheet (2) away from the transverse sheet (1).

6. The fiber optic grating load vibration monitoring device for the load-bearing structure of a wooden ancient building according to claim 1, characterized in that: Both the load strain grating (5) and the vibration strain grating (6) are Bragg gratings, and both the load strain grating (5) and the vibration strain grating (6) are provided with a grating protective shell (19) on the outside.

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