A device for measuring decayed parts of wooden beams in ancient buildings and a repair method

Abstract

The present invention provides a measuring device and repair method for the decayed part of a wooden beam in an ancient building, which aims at the problem that it is difficult to determine the cutting position of the decayed part of the wooden beam in the ancient building. The device comprises a base connected to the top of the wooden beam, a positioning sleeve connected to the groove shaft at the cantilevered end of the base, and an impact steel rod connected to the positioning sleeve. Method: the telescopic length between the impact steel rod and the positioning sleeve is adjusted and locked, so that the distance between the center of the hollow steel ball and the end of the positioning sleeve is equal to the distance between the center of the impact point of the wooden beam and the upper surface of the wooden beam. The base is connected to the upper surface of the wooden beam, the impact steel rod is lifted to a horizontal position and then released, the hollow steel ball impacts the side of the wooden beam to form an impact indentation, the wood decay degree judgment coefficient is obtained by fitting the measured indentation diameter, wood density, moisture content and other parameters, the wood decay degree of each impact point is measured one by one from the end to the middle of the wooden beam, and the area where the wood decay degree judgment coefficient is greater than a set value is determined as a decayed part, which needs to be removed and updated.

Description

Technical Field

[0001] The invention relates to the technical field of protection and repair of wooden structures of ancient buildings, and in particular to a measuring device and a repair method for decayed parts of wooden beams in ancient buildings. Background Art

[0002] The wooden beams in the wooden structures of ancient buildings are the main load-bearing components. Due to natural erosion, fungal invasion or insect bites, serious groove decay often occurs at the tenon position of the end of the wooden beam, and even the tenon dislocation phenomenon occurs, which seriously affects the structural safety. The existing repair methods for the tenon dislocation phenomenon caused by the decay of the end of the wooden beam mainly refer to the "Technical Standard for Maintenance and Reinforcement of Wooden Structures of Ancient Buildings" (GB / T50165-2020), as follows: first remove the rotten part of the original component, and open a mortise at the end of the beam, and insert the new tenon into the mortise. The tenon and the original component are glued with epoxy structural adhesive and fastened with iron parts. However, in actual projects, the specific removal position of the rotten part mainly depends on the naked eye observation and experience judgment of the construction workers. It is difficult to determine the optimal removal position of the rotten part of the wooden beam end. Excessive removal is not conducive to the preservation of the components of ancient building cultural relics, and too little removal affects the repair effect of the components and it is difficult to ensure the structural strength. Summary of the invention

[0003] The cutting position of the decayed part of the wooden beam in the existing ancient building depends on the naked eye observation and experience judgment of the construction workers, and it is difficult to determine the optimal cutting position of the decayed part of the wooden beam end. The purpose of the present invention is to provide a measuring device and a repair method for the decayed part of the wooden beam in the ancient building.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a device for measuring the decayed part of a wooden beam in an ancient building, comprising:

[0005] A base, wherein a fixed end on one side of the base is detachably connected to the top of the wooden beam to be repaired, and a cantilevered end on the other side is cantilevered outside the wooden beam to be repaired, and a groove is provided in the middle of the cantilevered end for installing a positioning sleeve;

[0006] A positioning sleeve, the top end of which is embedded in the groove and connected to the groove shaft;

[0007] The impact steel rod comprises a hollow steel ball and a connecting rod, one end of the connecting rod is fixedly connected to the hollow steel ball, and the other end of the connecting rod is detachably connected to a positioning sleeve.

[0008] The device for measuring the decayed part of a wooden beam in an ancient building of the present invention comprises a base detachably connected to the top of the wooden beam to be repaired, a positioning sleeve connected to a groove shaft at the cantilevered end of the base, and an impact steel rod detachably connected to the positioning sleeve, wherein a hollow steel ball at the end of the impact steel rod is used to impact the surface of the wooden beam to be repaired to form an impact indentation; the impact steel rod is lifted to a horizontal position and then released, and the hollow steel ball freely falls to impact the side of the wooden beam to form an impact indentation, and a calculation formula for a coefficient for judging the degree of decay of the wood is obtained by fitting the measured parameters such as the indentation diameter, wood density, and moisture content, and the degree of decay of the wood at each impact point is measured one by one from the end to the middle of the wooden beam, and an area where the coefficient for judging the degree of decay of the wood is greater than a set value is determined to be a decayed part and needs to be removed and updated; under the premise of satisfying the minimum intervention principle and ensuring the strength of the component, the measuring device can be used to quickly and accurately measure the removal position of the decayed part at the end of the wooden beam at the construction site; moreover, the measuring device has low manufacturing cost, convenient operation, easy implementation, and high construction efficiency.

[0009] Furthermore, at least three positioning holes are arranged at the fixed end of the base, and the three positioning holes are symmetrically arranged along the axis of the groove. The base is temporarily fixed to the upper surface of the wooden beam to be repaired by screws or steel nails passing through the positioning holes.

[0010] Furthermore, it also includes a level arranged on the top of the base.

[0011] Furthermore, the positioning sleeve is composed of two parts: a hollow sleeve and a solid rod that are integrally formed. The side wall of the hollow sleeve is provided with a plurality of equally spaced through holes. The solid rod of the positioning sleeve is provided with a through hole at the center. The round rod bearing passes through the through hole of the solid rod, and both ends of the round rod bearing are embedded in the corresponding blind holes in the middle of the inner wall of the base groove, so that the positioning sleeve can rotate freely around the round rod bearing.

[0012] Furthermore, the connecting rod side wall is provided with through holes corresponding to the number and position of the hollow sleeve, the connecting rod of the impact steel rod is embedded in the hollow sleeve of the positioning sleeve, the screw rod passes through the corresponding through holes of the connecting rod and the hollow sleeve and is locked and fixed by a nut.

[0013] In addition, the present invention also provides a method for repairing the decayed part of the wooden beam in the ancient building, the steps are as follows:

[0014] S1: Preliminarily determine the rotten part farthest from the end of the wood beam to be repaired, draw the positioning line of the impact indentation according to the height of the wood beam section, and mark the center position of each impact point along the positioning line; embed the connecting rod of the impact steel rod into the hollow sleeve of the positioning sleeve, adjust the telescopic length between the connecting rod and the hollow sleeve, so that the distance between the center of the hollow steel ball and the end of the positioning sleeve is approximately equal to the distance between the center of the impact point of the wood beam and the upper surface of the wood beam, pass the screw through the corresponding through hole of the overlapping area of ​​the connecting rod and the hollow sleeve and lock it with a nut, and record the length of the positioning sleeve and the impact steel rod at this time as L;

[0015] S2: Connect the fixed end of the base to the upper surface of the wooden beam to be repaired, and align the inner edge of the groove of the base with the edge of the upper surface of the wooden beam. Lift the impact steel rod to a horizontal position. After releasing the impact steel rod, the hollow steel ball falls freely and impacts the side of the wooden beam to form an impact indentation. Measure the diameter of the impact indentation on the side of the wooden beam, which is recorded as the indentation diameter d;

[0016] S3: The decay degree of the end of the wood beam is determined by the measured indentation diameter, wood density, moisture content and other parameters, and the wood decay degree judgment coefficient k is obtained. The calculation formula is as follows:

[0017] ;

[0018] In the formula, k is the coefficient for judging the degree of wood decay;

[0019] L is the length of the positioning sleeve and the impact steel rod after they are locked and fixed, in mm;

[0020] d is the indentation diameter, in mm;

[0021] ρ is the material density of the wooden beam to be repaired, in g / cm 3

[0022] w is the moisture content of the wood beam to be repaired, %;

[0023] When k ≥ 2.5, it is judged that the wood in the impact point area is seriously decayed and needs to be removed and replaced with new wood;

[0024] When k < 2.5, it is judged that the wood in the impact point area has not decayed or the degree of decay is not enough to affect the strength of the component, and it does not need to be removed for the time being;

[0025] S4: Move the measuring device gradually from the end of the wood beam to be repaired to the middle at equal intervals, and determine the wood decay degree judgment coefficient k of each impact point one by one. The area where the impact point with k≥2.5 is located is the decayed part. Draw a vertical line with the center of the impact point located at the edge of the decayed part as the critical line of the decayed part of the wood beam. Finally, cut off the decayed part at the end of the wood beam along the critical line of the decayed part, make a new tenon and fix it to the cut-off surface of the original wood beam, and then carry out repairs.

[0026] The method for repairing the decayed part of the wooden beam in the ancient building of the present invention comprises the following steps: firstly, preliminarily judging the decayed part farthest from the end of the wooden beam, marking the center position of the impact point respectively, adjusting the telescopic length between the impact steel rod and the positioning sleeve so that the distance between the center of the hollow steel ball and the end of the positioning sleeve is equal to the distance between the center of the impact point of the upper half of the wooden beam and the upper surface of the wooden beam, the screw rod passes through the through hole corresponding to the overlapping area of ​​the impact steel rod and the positioning sleeve and is locked and fixed by a nut, recording the length of the positioning sleeve and the impact steel rod, connecting the base to the upper surface of the wooden beam to be repaired, lifting the impact steel rod to a horizontal position and then releasing it, the hollow steel ball impacts the side of the wooden beam to form an impact indentation, accurately measuring the diameter of the impact indentation, and fitting the measured indentation diameter, wood density, moisture content and other parameters to obtain a calculation coefficient for judging the degree of wood decay. The calculation formula is used to measure the degree of wood decay at each impact point from the end to the middle of the wooden beam. The area where the wood decay degree judgment coefficient is greater than a set value is judged as the decayed part, which needs to be removed and updated; the repair method uses the calculation formula of the wood decay degree judgment coefficient obtained by fitting parameters such as indentation diameter, wood density, and moisture content to measure the decay degree of each impact point one by one and delineate the decayed part. It is easy to operate, has high construction efficiency, has little interference with wooden components, and does not damage its internal structure; because it can quickly, conveniently and accurately measure the decay degree of the rotten part at the end of the wooden beam at the construction site, it helps construction personnel to accurately find the critical line of the decayed part, thereby determining the specific removal position of the decayed part at the end of the wooden beam, which can not only ensure the strength of the wooden components, but also retain the original wooden components to the greatest extent.

[0027] Furthermore, step S2 also includes bonding carbon paper to the surface of the impact detection area on the side of the wooden beam to be repaired, forming an impact indentation after the hollow steel ball impacts the impact point on the side of the wooden beam, and measuring the diameter of the impact indentation printed on the side of the wooden beam by the carbon paper.

[0028] Furthermore, the step S2 also includes inserting a gasket under the base before the fixed end of the base is fastened to the top of the wooden beam to be repaired, and observing the level until the base is horizontally and stably supported on the top of the wooden beam to be repaired. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of an embodiment of a device for measuring the decayed part of a wooden beam in an ancient building of the present invention;

[0030] Figure 2 for Figure 1 Assembly diagram of each component;

[0031] Figure 3 A schematic diagram of a repair method using a device for measuring decayed parts of wooden beams in an ancient building according to an embodiment of the present invention;

[0032] Figure 4It is a schematic diagram of the impact indentation and critical line of the decayed part of the end of the wooden beam in one embodiment of the present invention.

[0033] The numbers in the figure are as follows:

[0034] Wooden beam 1; rotten part 2; base 11; positioning hole 12; level 14; groove 15; blind hole 16; solid rod 21; hollow sleeve 22; round rod bearing 23; through hole 24; screw 25; hollow steel ball 31; connecting rod 32. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. For the convenience of description, the "upper" and "lower" described below are consistent with the upper and lower directions of the drawings, but this cannot be a limitation of the technical solution of the present invention. Embodiment 1

[0036] Combination Figures 1 to 4 The measuring device for the decayed part of the wooden beam in the ancient building of the present invention is described, and it comprises:

[0037] The base 11 is a rectangular steel member with a size of 120 mm × 60 mm × 20 mm. The fixed end of one side of the base 11 is detachably connected to the top of the wooden beam 1 to be repaired. The other side of the base 11 is cantilevered outside the wooden beam 1 to be repaired, which is a cantilevered end. A groove 15 is provided in the middle of the cantilevered end for installing a positioning sleeve. The width of the groove 15 is 20 mm, and the inward depth of the groove 15 is 40 mm.

[0038] A positioning sleeve, the top end of which is embedded in the groove 15 and connected to the groove 15 axis;

[0039] The impact steel rod comprises a hollow steel ball 31 and a connecting rod 32. One end of the connecting rod 32 is fixedly connected to the hollow steel ball 31, and the other end thereof is detachably connected to the positioning sleeve.

[0040] The device for measuring the decayed part of the wooden beam in the ancient building of the present invention comprises a base 11 detachably connected to the top of the wooden beam 1 to be repaired, a positioning sleeve axially connected to the groove 15 at the cantilevered end of the base 11, and an impact steel rod detachably connected to the positioning sleeve. The hollow steel ball 31 at the end of the impact steel rod is used to impact the surface of the wooden beam 1 to be repaired to form an impact indentation. The impact steel rod is lifted to a horizontal position and then released, and the hollow steel ball 31 falls freely to impact the side of the wooden beam 1 to form an impact indentation. The measured indentation diameter, wood density, moisture content and other parameters are used to measure the decayed part of the wooden beam in the ancient building. The calculation formula of the wood decay degree judgment coefficient is obtained by numerical fitting, and the wood decay degree of each impact point is measured one by one from the end to the middle of the wooden beam 1, and the area where the wood decay degree judgment coefficient is greater than a set value is judged as the decayed part 2, which needs to be removed and updated; under the premise of meeting the minimum intervention principle and ensuring the strength of the component, the measurement device can be used to quickly and accurately measure the removal position of the decayed part 2 at the end of the wooden beam 1 at the construction site; moreover, the measurement device has low manufacturing cost, convenient operation, easy implementation, and high construction efficiency. The present invention is particularly suitable for the repair and construction of wooden beams 1 with larger cross-sectional dimensions and higher value in the wooden structure of palace-style ancient buildings.

[0041] like Figure 1 and Figure 2 As shown, three positioning holes 12 with a diameter of 7 mm are set at the fixed end of the base 11, and the three positioning holes 12 are symmetrically arranged along the axis of the groove 15. The base 11 is temporarily fixed to the upper surface of the wooden beam 1 to be repaired by three screws or steel nails with a diameter of 6 mm penetrating the positioning holes 12, so that the measuring device is stably connected to the top of the wooden beam 1 to be repaired.

[0042] like Figure 1 and Figure 2 As shown, the device for measuring the decay position of the wooden beam 1 in the ancient building of the present invention also includes a level 14 arranged on the top of the base 11. When the base 11 is installed on the top of the wooden beam 1 to be repaired, the level 14 is used to calibrate whether the base 11 is placed horizontally.

[0043] like Figure 2As shown, the positioning sleeve is composed of a hollow sleeve 22 and a solid rod 21 which are made into one piece. The overall size of the positioning sleeve is 150mm×20mm×20mm. The hollow sleeve 22 of the positioning sleeve is a hollow square steel tube with a wall thickness of 2mm. The side wall of the hollow sleeve 22 is provided with a plurality of equally spaced through holes 24. In this embodiment, the side wall of the hollow sleeve 22 is provided with 5 to 10 through holes 24 with a diameter of 5mm, and the center distance between two adjacent through holes 24 is 15mm; the solid rod 21 of the positioning sleeve is 30mm long, and a through hole 24 with a diameter of 6mm is provided at the center of the solid rod 21 20mm away from the tail edge. The round rod bearing 23 passes through the through hole 24 of the solid rod 21, and the two ends of the round rod bearing 23 are embedded in the blind holes 16 corresponding to the middle of the inner wall of the groove 15 of the base 11, and the distance between the round rod bearing 23 and the bottom surface of the groove 15 is 20mm, so that the positioning sleeve can rotate freely around the round rod bearing 23.

[0044] Please continue to refer to Figure 2 The end of the impact steel rod is a hollow steel ball 31 with a diameter of 45mm, a wall thickness of 5mm, and a mass of 900g. The connecting rod 32 is a solid steel pipe with a size of 120mm×16mm×16mm. The side wall of the connecting rod 32 is provided with through holes corresponding to the number and position of the hollow sleeve 22, and the diameter of the through hole is 5mm. The connecting rod 32 of the impact steel rod is embedded in the hollow sleeve 22 of the positioning sleeve, and the screw 25 passes through the corresponding through holes of the connecting rod 32 and the hollow sleeve 22 and is locked and fixed by a nut. When it is necessary to adjust the telescopic length between the positioning sleeve and the impact steel rod according to the height of the impact position, loosen the locking of the bolt and nut, adjust the extension length of the impact steel rod along the positioning sleeve, and make the through hole positions of the overlapping areas of the two correspond, and insert the screw 25 again into the through hole in the overlapping area and lock and fix it by a nut. In this embodiment, the length of the screw 25 is 40mm and the diameter is 5mm.

[0045] The dimensions of the components of the device for measuring the decayed portion 2 of a wooden beam 1 in an ancient building of this embodiment are determined according to common specifications of wooden beams 1 in ancient building repair projects, and can be applied to most ancient building wooden beam 1 repair projects. Embodiment 2

[0046] Combination Figures 1 to 4 The method for repairing the decayed part of the wooden beam in the ancient building of the present invention is described, using the device for measuring the decayed part of the wooden beam in the ancient building described in Example 1, and the specific steps are as follows:

[0047] S1: Perform an appearance inspection on the decayed end of the wooden beam 1 to be repaired, preliminarily determine the decayed part 2 farthest from the end of the wooden beam 1, observe the upper and lower parts of the wooden beam 1 respectively, record the distance between the decayed part 2 of the upper part of the wooden beam 1 and the end of the wooden beam 1 as L1, and the distance between the decayed part 2 of the lower part of the wooden beam 1 and the end of the wooden beam 1 as L2, draw the positioning lines of the impact indentations of the upper and lower parts respectively according to the cross-sectional height of the wooden beam 1, and mark the center position of each impact point along the positioning line; embed the connecting rod 32 of the impact steel rod into the hollow sleeve 22 of the positioning sleeve, adjust the telescopic length between the connecting rod 32 and the hollow sleeve 22, so that the distance between the center of the hollow steel ball 31 and the end of the positioning sleeve is approximately equal to the distance between the center of the impact point of the upper part of the wooden beam 1 and the upper surface of the wooden beam 1, pass the screw 25 through the through hole corresponding to the overlapping area of ​​the connecting rod 32 and the hollow sleeve 22 and lock it with a nut, and record the length of the positioning sleeve and the impact steel rod at this time as L;

[0048] S2: Place the disassembled wooden beam 1 to be repaired flat on the ground, connect the fixed end of the base 11 to the upper surface of the wooden beam 1 to be repaired, and align the inner edge of the groove 15 of the base 11 with the edge of the upper surface of the wooden beam 1, lift the impact steel rod to a horizontal position, and after releasing the impact steel rod, the hollow steel ball 31 falls freely and impacts the side of the wooden beam 1 to form an impact indentation, and accurately measure the diameter of the impact indentation on the side of the wooden beam 1, which is recorded as the indentation diameter d;

[0049] S3: The decay degree of the end of the wooden beam 1 is determined by the measured indentation diameter, wood density, moisture content and other parameters, and the wood decay degree judgment coefficient k is obtained. The calculation formula is as follows:

[0050] ;

[0051] In the formula, k is the coefficient for judging the degree of wood decay;

[0052] L is the length of the positioning sleeve and the impact steel rod after they are locked and fixed, in mm;

[0053] d is the indentation diameter, in mm;

[0054] ρ is the material density of the wood beam 1 to be repaired, in g / cm 3

[0055] w is the moisture content of the wood beam 1 to be repaired, %;

[0056] When k≥2.5, it is judged that the wood in the impact point area is seriously decayed and needs to be removed and replaced with new wood; when k<2.5, it is judged that the wood in the impact point area has not yet decayed or the degree of decay is not enough to affect the strength of the component, and it does not need to be removed for the time being. Figure 4As shown, the solid circle a represents the impact indentation with k ≥ 2.5, the hollow circle b represents the impact indentation with k < 2.5, the dotted line represents the critical line of the decayed part 2 to be removed, and the dotted line c represents the side center line of the wooden beam 1; this step is to observe the correlation between the results and various parameters after conducting decay impact tests on a large number of woods of different decay degrees and different tree species, and it is found that the decay degree of wood is strongly correlated with parameters such as impact indentation, wood density and moisture content. It is proposed to use key parameters such as impact indentation, wood density and moisture content to judge the decay degree of wooden components, and the wood decay degree judgment formula obtained by analyzing and fitting the corresponding parameters has a high judgment accuracy.

[0057] S4: Move the measuring device gradually from the end of the wooden beam 1 to be repaired to the middle every 60mm, and obtain the wood decay degree judgment coefficient k of each impact point one by one. The area where the impact point is located where k≥2.5 is the decayed part 2. Draw a vertical line with the center of the impact point located at the edge of the decayed part 2 as the center, as the critical line of the decayed part 2 of the wooden beam 1, and find the critical line of the decayed part 2 in the upper and lower halves of the end of the wooden beam 1 respectively, that is, after the critical line of the decayed part 2 in the upper half is determined, turn over the wooden beam 1, fix the base 11 to the other bottom surface of the wooden beam 1, repeat the above steps, find the critical line of the decayed part 2 in the lower half of the wooden beam 1, and the critical line is the cutting line of the decayed part 2 at the end of the wooden beam 1. Finally, cut off the decayed part 2 at the end of the wooden beam 1 along the critical line of the decayed part 2 in the upper and lower halves, and refer to the original size of the original wooden beam 1, use the same tree species or higher grade wood to make a new tenon, and splice and fix it to the cut-off surface of the original wooden beam 1 for repair.

[0058] The method for repairing the decayed part of the wooden beam in the ancient building of the present invention comprises the following steps: first, preliminarily judging the decayed part 2 farthest from the end of the wooden beam 1, marking the center position of the impact point respectively, adjusting the telescopic length between the impact steel rod and the positioning sleeve, making the distance between the center of the hollow steel ball 31 and the end of the positioning sleeve equal to the distance between the center of the impact point of the upper half of the wooden beam 1 and the upper surface of the wooden beam 1, the screw rod 25 passes through the through hole 24 corresponding to the overlapping area of ​​the impact steel rod and the positioning sleeve and is locked and fixed by a nut, recording the length of the positioning sleeve and the impact steel rod, connecting the base 11 to the upper surface of the wooden beam 1 to be repaired, lifting the impact steel rod to a horizontal position and then releasing it, the hollow steel ball 31 impacts the side of the wooden beam 1 to form an impact indentation, accurately measuring the diameter of the impact indentation, and fitting the measured indentation diameter, wood density, moisture content and other parameters to obtain the judgment of the degree of wood decay. The calculation formula of the coefficient is used to measure the wood decay degree of each impact point one by one from the end to the middle of the wooden beam 1, and the area where the wood decay degree judgment coefficient is greater than a set value is judged as the decayed part 2, which needs to be removed and updated; the repair method uses the calculation formula of the wood decay degree judgment coefficient obtained by fitting parameters such as indentation diameter, wood density, and moisture content to measure the decay degree of each impact point one by one and delineate the decayed part 2. It is easy to operate, has high construction efficiency, has little interference with wooden components, and does not damage its internal structure; because it can quickly, conveniently and accurately measure the decay degree of the rotten part at the end of the wooden beam 1 at the construction site, it helps construction personnel to accurately find the critical line of the decayed part 2, thereby determining the specific removal position of the decayed part 2 at the end of the wooden beam 1, which can not only ensure the strength of the wooden components, but also retain the original wooden components to the greatest extent.

[0059] The step S2 also includes bonding carbon paper to the surface of the impact detection area on the side of the wooden beam 1 to be repaired, and forming an impact indentation after the hollow steel ball 31 impacts the impact point on the side of the wooden beam 1, and using a vernier caliper to accurately measure the diameter of the impact indentation printed on the side of the wooden beam 1 by the carbon paper. The imprint of the carbon paper can mark the impact point position on the surface of the wooden beam 1 more clearly and without damage.

[0060] The step S2 also includes inserting a gasket under the base 11 and observing the level 14 before the fixed end of the base 11 is fastened to the top of the wooden beam 1 to be repaired, until the base 11 is horizontally and stably supported on the top of the wooden beam 1 to be repaired.

[0061] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of the claims.

Claims

1. A method for repairing the decayed part of a wooden beam in an ancient building, the measuring device used comprises: A base, wherein a fixed end on one side of the base is detachably connected to the top of the wooden beam to be repaired, and a cantilevered end on the other side is cantilevered outside the wooden beam to be repaired, and a groove is provided in the middle of the cantilevered end for installing a positioning sleeve; a positioning sleeve, wherein the top end of the positioning sleeve is embedded in the groove and connected to the groove shaft; an impact steel rod, comprising a hollow steel ball and a connecting rod, wherein one end of the connecting rod is fixed to the hollow steel ball, and the other end thereof is detachably connected to the positioning sleeve; the steps are as follows: S1: Preliminarily determine the rotten part farthest from the end of the wood beam to be repaired, draw the positioning line of the impact indentation according to the height of the wood beam section, and mark the center position of each impact point along the positioning line; embed the connecting rod of the impact steel rod into the hollow sleeve of the positioning sleeve, adjust the telescopic length between the connecting rod and the hollow sleeve, so that the distance between the center of the hollow steel ball and the end of the positioning sleeve is equal to the distance between the center of the impact point of the wood beam and the upper surface of the wood beam, pass the screw through the through hole corresponding to the overlapping area of ​​the connecting rod and the hollow sleeve and lock it with a nut, and record the length of the positioning sleeve and the impact steel rod at this time as L; S2: Connect the fixed end of the base to the upper surface of the wooden beam to be repaired, and align the inner edge of the groove of the base with the edge of the upper surface of the wooden beam. Lift the impact steel rod to a horizontal position. After releasing the impact steel rod, the hollow steel ball falls freely and impacts the side of the wooden beam to form an impact indentation. Measure the diameter of the impact indentation on the side of the wooden beam, which is recorded as the indentation diameter d; S3: The decay degree of the end of the wood beam is determined by the measured indentation diameter, wood density, and moisture content parameters, and the wood decay degree judgment coefficient k is obtained. The calculation formula is as follows: ； In the formula, k is the coefficient for judging the degree of wood decay; L is the length of the positioning sleeve and the impact steel rod after they are locked and fixed, in mm; d is the indentation diameter, in mm; ρ is the material density of the wooden beam to be repaired, in g / cm 3 ; w is the moisture content of the wood beam to be repaired, %; When k ≥ 2.5, it is judged that the wood in the impact point area is seriously decayed and needs to be removed and replaced with new wood; When k < 2.5, it is judged that the wood in the impact point area has not decayed or the degree of decay is not enough to affect the strength of the component, and it does not need to be removed for the time being; S4: Move the measuring device gradually from the end of the wood beam to be repaired to the middle at equal intervals, and determine the wood decay degree judgment coefficient k of each impact point one by one. The area where the impact point with k≥2.5 is located is the decayed part. Draw a vertical line with the center of the impact point located at the edge of the decayed part as the critical line of the decayed part of the wood beam. Finally, cut off the decayed part at the end of the wood beam along the critical line of the decayed part, make a new tenon and fix it to the cut-off surface of the original wood beam, and then carry out repairs.

2. The method for repairing the decayed part of the wooden beam in the ancient building according to claim 1, characterized in that: The step S2 also includes bonding carbon paper to the surface of the impact detection area on the side of the wooden beam to be repaired, forming an impact indentation after the hollow steel ball impacts the impact point on the side of the wooden beam, and measuring the diameter of the impact indentation printed on the side of the wooden beam by the carbon paper.

3. The method for repairing the decayed part of the wooden beam in the ancient building according to claim 1, characterized in that: The step S2 also includes inserting a gasket under the base before the fixed end of the base is fastened to the top of the wooden beam to be repaired, and observing the level until the base is horizontally and stably supported on the top of the wooden beam to be repaired.

4. The method for repairing the decayed part of the wooden beam in the ancient building according to claim 1, characterized in that: The fixed end of the base is provided with three positioning holes, and the three positioning holes are symmetrically arranged along the axis of the groove. The base is temporarily fixed to the upper surface of the wooden beam to be repaired by screws or steel nails penetrating the positioning holes.

5. The method for repairing the decayed part of the wooden beam in the ancient building according to claim 1, characterized in that: The positioning sleeve is composed of two parts: a hollow sleeve and a solid rod that are made into one piece. The side wall of the hollow sleeve is provided with a plurality of equally spaced through holes. The center of the solid rod of the positioning sleeve is provided with a through hole. The round rod bearing passes through the through hole of the solid rod, and both ends of the round rod bearing are embedded in the blind holes corresponding to the middle part of the inner wall of the base groove, so that the positioning sleeve can rotate freely around the round rod bearing.

6. The method for repairing the decayed part of the wooden beam in the ancient building according to claim 1, characterized in that: The connecting rod side wall is provided with through holes corresponding to the number and position of the hollow sleeve. The connecting rod of the impact steel rod is embedded in the hollow sleeve of the positioning sleeve. The screw rod passes through the corresponding through holes of the connecting rod and the hollow sleeve and is locked and fixed by a nut.

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