JP2010008258A - Strength evaluation method of wood and repair diagnosing method of structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a strength evaluation method of wood which enables the evaluation of the compression strength of evaluation target wood, and a repair diagnosing method of a structure. <P>SOLUTION: Average resistance values and compression strength values in interpenetration of a drill 22 are separately measured with respect to the test pieces cut from a plurality of woods: from these correlation data, the relational expression of the average resistance values and the compression strength values in interpenetration of the drill 22 into the woods is calculated. Next, the drill 22 of a resist graph 10 is interpenetrated in the evaluation target wood T and the average resistance value in interpenetration is set as an evaluated resistance value. Then, the compression strength value of the evaluation target wood is calculated on the basis of the evaluated resistance value and the preliminarily obtained relational expression. By this method, the compression strength of the evaluation target wood only cleared in the presence of a deteriorated place heretofore is evaluated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wood strength evaluation method and a structural repair diagnosis method used for determining whether or not a wooden structure needs to be repaired.

  With the increase in renovation work for wooden structures, it is required to diagnose the soundness (necessity of renovation) of the target structure before renovation work. In particular, when it is desired to perform repair work while leaving as much structural material (wood) as possible used, it is necessary to grasp the strength performance (for example, compressive strength) of the structural member in consideration of the deterioration state. However, a soundness evaluation method including the strength performance of the structural member has not been established.

  Examples of methods for objectively evaluating only the degradation state of wood include a pin driving depth measuring method, an ultrasonic measuring method, and a nail pulling resistance measuring method. In the pin driving depth measurement method, a pin (length 4 cm or 7 cm) is driven into wood with a constant force, and soundness is judged by the penetration depth of the pin into the wood. In the ultrasonic measurement method, the ultrasonic propagation time between two sensors sandwiching wood is measured, and the soundness is judged from the magnitude of the propagation speed. The nail pull-out resistance measurement method determines soundness from the pull-out resistance force of a nail that has been driven with a constant force.

  On the other hand, as another evaluation method, there is a wood decay evaluation method (for example, see Patent Documents 1 and 2). In the wood deterioration diagnosis method of Patent Document 1, the evaluation target wood is hit with an impact hammer, and the hitting speed and the maximum hitting force are obtained from the obtained measurement waveform to diagnose the degree of deterioration. In the wood decay evaluation method of Patent Document 2, a part of an evaluation target wood is collected as a sample piece, accommodated in a sealed container together with a culture medium, and based on the concentration of hydrogen generated from the sealed container after a predetermined period of time. The degree of decay is evaluated.

However, all of the above evaluation methods only specify the deteriorated portion of the structural member, and do not grasp the strength performance of the structural member.
JP 2002-257700 A JP 2004-286590 A

  It is an object of the present invention to obtain a wood strength evaluation method and a structure repair diagnosis method capable of evaluating the compressive strength of an evaluation target wood.

  The wood strength evaluation method according to claim 1 of the present invention includes a resistance value when a drill is inserted into the evaluation target wood, an average resistance value obtained when the drill is inserted into the wood, and a compressive strength value of the wood. Based on the relational expression, the compression strength value of the evaluation target wood is obtained.

  According to the said structure, a relational expression is previously calculated | required by the correlation data of the average resistance value at the time of drill penetration, and a compressive strength value about wood. And the predicted value of the compressive strength of evaluation object wood is obtained only by substituting the resistance value obtained by penetrating the evaluation object wood into the relational expression. Thereby, conventionally, it is possible to evaluate the compressive strength without performing the compressive strength measurement on the evaluation target wood which has been known only in the presence or absence of the deteriorated portion.

  In the wood strength evaluation method according to claim 2 of the present invention, the average resistance value at the time of penetration is the two resistances obtained by penetrating the drill so that the drill does not intersect from two directions perpendicular to each other. The values are further averaged to obtain an average resistance value.

  According to the above configuration, even if there is some variation in the resistance value at the time of drill penetration in the fiber direction, the radial direction, and the tangential direction of the wood, even if there is some variation in the resistance value at the time of drill penetration, Variations can be reduced.

  According to claim 3 of the present invention, there is provided a method for diagnosing a structural repair, wherein the compression strength value of the evaluation target wood obtained by the wood strength evaluation method according to claim 1 or claim 2, and the reference compression strength value of the wood Are compared to diagnose the necessity of repair of the structure including the evaluation target wood.

  According to the above configuration, by inserting a drill into the evaluation target wood and measuring the resistance value, it is possible to estimate the compressive strength value without almost damaging the evaluation target wood, and using this compressive strength value, Diagnosis can be easily made up to the necessity of repair.

  Since this invention was set as the said structure, the compressive strength of evaluation object timber can be evaluated.

  Embodiments of a wood strength evaluation method and a structure repair diagnosis method according to the present invention will be described with reference to the drawings. Here, an evaluation method using a resist penetration graph (Resistograph: registered trademark) manufactured by Instrumenta_Mechanik_Labor_GmbH of Germany and model IML-RESI_F300 will be described.

  As shown in FIG. 1, the resist graph 10 is provided on a main body portion 12 made of a substantially rectangular parallelepiped box whose longitudinal direction is the direction toward the evaluation target wood T, and on the bottom surface side of the main body portion 12. And a grip portion 14 that grips and supports the main body portion 12.

  Inside the main body 12, a drill 22 whose axial direction is the direction toward the evaluation target wood T, and a drive unit (not shown) that performs rotation drive (arrow R direction) and straight drive (arrow X direction) of the drill 22. Is stored. The drill 22 is a special alloy drill in which a 3 mm wide cone is attached to the tip of a steel shaft having a diameter of 1.5 mm. Further, the drill 22 is movable toward the evaluation target wood T through an opening formed on the surface of the main body 12 facing the evaluation target wood T.

  In addition, a measurement unit (not shown) that measures and quantifies internal resistance (penetration resistance) received when the drill 22 penetrates the evaluation target wood T is obtained inside the main body unit 12, and is obtained by the measurement unit. And a storage unit (not shown) for storing the measured values. The penetration resistance of the drill 22 measured by the measurement unit is not only stored in the storage unit, but also output as a waveform graph to the chart recorder 18 provided on the upper portion of the main body unit 12.

  The coordinate resolution when the drill 22 penetrates into the evaluation target wood T is 0.1 mm. The length of the drill 22 is 300 mm in the above model, but 400 mm and 500 mm can be selected by selecting the model of the resist graph 10 according to the application. Further, conical wedge portions 20 that are in contact with the evaluation target wood T are provided at three locations around the above-described opening through which the drill 22 moves.

  On the other hand, a battery unit 16 is provided at the bottom of the gripping unit 14 and is connected to a charger and supplies power to the drive unit of the resist graph 10. Further, the grip 14 is provided with a switch 24 that is switched ON and OFF when the measurer grips and presses the grip 14 and starts or stops the operation of the resist graph 10.

  In the resist graph 10, two types of measurement levels (level 1 and level 2) can be selected according to the hardness of the evaluation target wood T. In general, Level 1 covers coniferous timber and Level 2 covers hardwood timber.

  FIG. 2 is a graph showing an example of the measurement result of the penetration resistance value when the drill 22 is penetrated into wood having a measurement thickness of 100 mm using the resist graph 10. The graph of FIG. 2 is a smooth curve because the obtained data is displayed after smoothing processing, but the actual graph has a variation in penetration resistance values in the vertical direction.

  The horizontal axis of the graph is the penetration depth of the drill 22 from the surface of the evaluation target wood T, and the vertical axis is the penetration resistance value measured when the drill 22 penetrates. One scale on the horizontal axis corresponds to 10 mm, but one scale on the vertical axis is not set as a unit, and is used as a value for relatively comparing the penetration resistance of the drill 22.

  The graph of FIG. 2 is measured for healthy wood without deterioration. Here, the penetration depth at which a plurality of peaks are seen is a position corresponding to an annual ring of wood, and indicates that the position is hard. In addition, when using wood that has deteriorated parts due to decay, etc., the penetration resistance value remains zero or close to zero at the penetration depth of the deteriorated part, so it is possible to determine the deteriorated part. .

  Next, a method for creating a test piece will be described. This test piece is prepared in order to obtain correlation data between the penetration resistance according to the resist graph 10 (see FIG. 1) and the compressive strength described later.

  FIG. 3A shows a large beam 32 of the wooden structure 30 at the time of dismantling selected for obtaining a test piece. Here, the girder 32 is made of beige laminated wood, and is considered to be sounder (a state in which the decay has not progressed relatively) compared to the decay area A (shaded area in the figure) and the decay area A. A description will be given assuming that the healthy region B exists.

  The determination of the presence or absence of the decay area A may not be based on an objective method performed by penetration resistance measurement or the like, but may be performed based on empirical determination such as visual inspection, percussion, palpation, and smell. This is because a low penetration resistance value may be obtained as compared with the penetration resistance value of the healthy region B. Here, in order to obtain a test piece, a rectangular parallelepiped block 34 including the decay area A and the healthy area B is cut out from the large beam 32.

  Subsequently, as shown in FIG. 3B, the cut block 34 is further divided into a plurality of blocks 36 and 38, and an adhesive layer is formed for each lamina layer constituting the blocks 36 and 38. The plate materials 36A to 36E and the plate materials 38A to 38E are cut out so as not to be included. The thicknesses of the cut plate materials 36A to 36E and plate materials 38A to 38E are 20 to 25 mm.

  Subsequently, as shown in FIG. 3C, the individual plate members 36A to 36E and the plate members 38A to 38E are cut into strips to produce rod-shaped members 40A to 40E. Then, test pieces of 20 mm × 20 mm × 40 mm are cut out from the decay area A and the healthy area B of each rod-like material 40A to 40E. In addition, this test piece cuts out two sheets which adjoined in the same site | part as one set, and makes one the 1st test piece 42 and the other the 2nd test piece 44.

  Here, the reason for paying attention to the correlation between the penetration resistance and the compressive strength will be described. The penetration resistance represents the difficulty of penetration when the drill 22 is penetrated into wood. For this reason, the penetration resistance of the drill 22 generally increases as the density of the wood increases. On the other hand, the compressive strength of wood generally increases as the density of the wood increases.

  From these relationships, it is considered that when the penetration resistance is large, the compressive strength is also large, and the penetration resistance and the compressive strength can be evaluated as a substantially proportional relationship. If this relational expression was obtained by measurement in advance, it was thought that the compressive strength, which was difficult to measure locally, could be predicted from the penetration resistance that was easy to measure locally.

  Next, a penetration resistance measuring method using the first test piece 42 will be described.

  As shown in FIG. 4, the wood has three axes orthogonal to each other in the fiber direction (arrow L direction), the radial direction (arrow R direction), and the tangential direction (arrow T direction). The strength properties of wood vary greatly depending on the axial direction of these, but the dark summer wood part (the part that grew from summer to early autumn: also called late wood), which is recognized as an annual ring, and the light spring part (Parts grown from spring to early summer: also called early wood) have different strength properties.

  In consideration of the anisotropy of the strength property of the wood, the penetration direction of the drill 22 (see FIG. 1) into the first test piece 42 is set to two directions (arrows D1 and D2 directions). The direction of the arrow D1 and the direction of the arrow D2 are set so as to be substantially orthogonal in a plan view. In FIG. 4, a = b = 20 mm and c = 40 mm.

  In the penetration resistance measurement of the first test piece 42, first, the drill 22 of the resist graph 10 (see FIG. 1) is perpendicular to the side surface (LR plane) of the first test piece 42 and passes through the center of the cross section as much as possible. The penetration resistance is measured by penetrating in the direction of arrow D1.

  Subsequently, the drill 22 is moved in the direction of the arrow D2 so as not to intersect with the through hole formed by the measurement in the direction of the arrow D1 but perpendicular to the side surface (LT plane) of the first test piece 42 and through the center of the cross section as much as possible. The penetration resistance is measured by penetrating into. The obtained measurement data is integrated and averaged to obtain average penetration resistance values (X1 and X2) in the D1 and D2 directions.

  Here, in practice, the relationship between the penetration direction and the annual ring direction as shown in FIG. 4 is not necessarily established, and the annual ring direction takes various angles with respect to the cross section of each test piece. In order to reduce the influence of this angle, that is, the variation in the measured value due to the difference in angle, the average penetration resistance values X1 and X2 in two substantially orthogonal directions (D1 and D2 directions) are further averaged to obtain an average resistance value M. M = (X1 + X2) / 2. This average resistance value M is used as the penetration resistance value of the first test piece 42.

  In addition, since a pine is used as a test piece, the measurement sensitivity of the resist graph 10 may basically be level 1, but the measurement is also performed with the measurement sensitivity of level 2 here.

  Next, a compressive strength measuring method using the second test piece 44 will be described.

The compressive strength is measured by a test method according to JIS-Z2101 (wood test method). In addition, the longitudinal direction of the second test piece 44 is parallel to the fiber direction, and the compressive strength value σ is set such that the cross-sectional area of the second test piece 44 is A [mm ² ] and the maximum load is Pm [N]. It calculates | requires by (sigma) = Pm / A [N / mm < ² >].

  Next, a method for obtaining a relational expression between penetration resistance and compressive strength will be described.

  With the average resistance value M obtained with the first test piece 42 as the horizontal axis and the compressive strength value σ obtained with the second test piece 44 as the vertical axis, the plurality of first test pieces 42 and second test pieces 44 Regression analysis is performed using the obtained data. The regression equation (primary regression line) obtained in this way is used as a relational expression between penetration resistance and compressive strength. For reference, the 5% lower limit straight line is also obtained.

  Here, FIG. 5 shows a flowchart summarizing the above procedure for obtaining the relational expression between the penetration resistance of wood and the compressive strength. In FIG. 5, first, as step S <b> 1, a test piece is cut out from a decayed or sound structure wood. Subsequently, as step S <b> 2, the test piece is cut into a first test piece 42 and a second test piece 44.

  Subsequently, in step S <b> 3, the penetration resistance of the first test piece 42 is measured with the resist graph 10. On the other hand, in step S4, the compressive strength of the second test piece 44 is measured by a compression test.

  Subsequently, as step S5, a linear regression equation is obtained from a plurality of correlation data of the average resistance value M of penetration resistance measurement and the compressive strength value σ. By performing these procedures in advance, a relational expression between the penetration resistance and the compressive strength of the resist graph 10 (see FIG. 1) is prepared.

  Here, FIGS. 6 and 7 show measurement data of the average resistance value M and the compressive strength value σ of n = 104 (set) in the level 1 and level 2 measurement of the resist graph 10 as an example. 6 and 7 show the penetration resistance measurement of the same first test piece 42 with the sensitivity setting of the resist graph 10 set to levels 1 and 2, and the measurement number n = 104 (shared). In addition, as the compressive strength value, the compressive strength value obtained by the second test piece 44 is used for both Level 1 and Level 2.

  The compressive strength of the evaluation target wood T with respect to the penetration resistance of the drill 22 can be calculated (estimated) by the regression equation described in FIGS. 6 and 7 (R in the drawings is a correlation coefficient). Note that the test pieces (the first test piece 42 and the second test piece 44) include not only those that are completely decayed but also those that contain many healthy parts or those that are almost entirely healthy. However, regardless of the presence or absence of a healthy portion, the compressive strength of the portion is uniquely determined with respect to the obtained average resistance value. For this reason, the measurement result of this embodiment is applicable also to healthy material.

  Moreover, although FIG. 6, FIG. 7 is a measurement result using the test piece of a beige structural laminated material, since compressive strength is uniquely determined with respect to the average resistance value calculated | required as mentioned above, I think that these relational expressions do not differ greatly depending on the tree species (soft or hard). For this reason, it is considered that the relationship between the penetration resistance of the drill 22 and the compressive strength can be obtained even when other tree species are used. In particular, if the sensitivity of level 2 of the resist graph 10 is used, it can be applied to the soundness evaluation of relatively hard categories of wood.

  The moisture content of the n = 104 test pieces used in the measurements of FIGS. 6 and 7 was 11 to 14% when measured using a resistance moisture meter. This seems to be because, even when the wood is deteriorated, it is already dried when it is collected (cut out).

  Next, the operation of the embodiment of the present invention will be described. Here, it is assumed that a relational expression (regression formula) between the penetration resistance and the compressive strength is prepared in advance according to the flowchart of FIG.

  FIG. 8 shows a flowchart of a wood strength evaluation method and a structural repair diagnosis method. First, as step S1, a drill 22 of a resist graph 10 (see FIG. 1) is inserted into an evaluation target wood T of a local wooden structure that requires renovation diagnosis, and an average resistance value M (evaluation resistance value) is obtained. obtain. Here, penetration of the drill 22 is performed in two directions orthogonal to each other of the evaluation target wood T, and an average value of the two obtained resistance values is set as an evaluation resistance value.

  Subsequently, as step S2, the evaluation resistance value is substituted into the relational expression between the penetration resistance value and the compression strength, and the compression strength value σ of the evaluation target wood T is obtained. As a relational expression between penetration resistance and compressive strength, a linear regression equation is basically used, but a linear equation with a lower limit of 5% can also be used.

  Subsequently, as step S3, the compression strength value σ of the evaluation target wood T obtained in step S2 is compared with the reference compression strength value of the wood, and the repair of the local wooden structure including the evaluation target wood T is performed. Diagnose necessity. Here, the standard strength Fc (compressive strength) of wood of 2000 Ministry of Construction Notification No. 1452 is used as the standard compressive strength value of wood. Since the reference strength Fc varies depending on the tree type, classification, and grade, it is set according to the tree type, classification, and grade of the evaluation target wood T.

For example, Fuku = 27.0 [N / mm ² ] is obtained for the first grade structural material grade 1 used in this embodiment. Thus, when the compressive strength value σ obtained by the above regression equation is a value smaller than 27.0 [N / mm ² ], it is diagnosed that the local evaluation target wood needs to be replaced or reinforced. Moreover, when the obtained compressive strength value (sigma) is 27.0 [N / mm < ² >] or more, it diagnoses that replacement | exchange or reinforcement is unnecessary.

  As described above, according to the wood strength evaluation method and the structural repair diagnosis method of the present invention, correlation data between the average resistance value M when the drill 22 penetrates the resist graph 10 and the compressive strength value σ for wood. Thus, the regression equation is obtained in advance. And the estimated value of the compressive strength of the evaluation object wood T is obtained only by substituting the evaluation resistance value obtained by penetrating the drill 22 into the evaluation object wood T into the regression equation. Thereby, it is possible to evaluate the compressive strength without taking a sample and performing a strength test with the evaluation target wood T that has conventionally only known the presence or absence of a deteriorated portion.

  Moreover, even if there is some variation in the penetration resistance value of the drill 22 in the direction perpendicular to each other in the fiber direction, radial direction, and tangential direction of the wood, the variation in the measured value depending on the direction is reduced by averaging. Can do.

  Furthermore, the compressive strength value σ can be estimated by simply inserting the drill 22 into the evaluation target wood T and measuring the average resistance value M, and the obtained compressive strength value σ is compared with the reference strength of the wood to compare the wooden structure in the field. Since it is possible to diagnose whether or not the structure needs to be repaired, the repair diagnosis becomes easy.

  Moreover, in the measurement of penetration resistance value, only a hole with a diameter of about 3 mm is formed in the evaluation target wood T, and it is mixed with nodes, scratches, surface dirt, etc. that originally exist around the hole, and the hole is hardly recognized. Strength estimation and repair diagnosis can be performed in a state close to nondestructive inspection.

  Moreover, even if the evaluation target wood T is a member having a large cross section, the compression strength can be accurately estimated including the inside of the member from the result of simple field measurement. Compared to the case where the test is performed, the cost of dismantling, transportation, experiment, etc. becomes unnecessary. Furthermore, since the strength of the evaluation target wood T can be estimated in a short time, the earthquake-resistant reinforcement can be planned and executed quickly.

  In addition, this invention is not limited to said embodiment.

  The tree species of the target wood T is not limited to the torch, but includes most coniferous trees such as cedar, hinoki and karamatsu, and various hardwoods such as zelkova and chestnut, and most of the wood that can be measured with the resist graph 10. Can be targeted.

  In the present embodiment, the number of correlation data n between the penetration resistance value and the compressive strength value is 104, but the present invention is not limited to this, and the number of data can be arbitrarily set. From the viewpoint of obtaining an accurate regression equation, it is desirable that the number of n is larger, and it is necessary to prepare a test piece so that the distribution of penetration resistance values becomes wider.

It is the schematic of the resist graph which concerns on embodiment of this invention. It is a graph of the penetration resistance value with respect to the penetration depth of the drill obtained by the resist graph which concerns on embodiment of this invention. (A)-(c) It is process drawing which shows the cutting-out method of the test piece which concerns on embodiment of this invention. It is a perspective view of the test piece which concerns on embodiment of this invention. It is a flowchart which shows the preparation method of the relational expression of the penetration resistance of wood and compressive strength which concerns on embodiment of this invention. It is a graph which shows the relationship between an average resistance value and compressive strength when the test piece which concerns on embodiment of this invention is measured by the sensitivity of the level 1 of a resist graph. It is a graph which shows the relationship between an average resistance value and compressive strength when the test piece which concerns on embodiment of this invention is measured by the sensitivity of the level 2 of a resist graph. It is a flowchart which shows the strength evaluation method of the wood which concerns on embodiment of this invention, and the repair diagnostic method of a structure.

Explanation of symbols

10 Registration Graph 22 Drill (Drill)
42 First test piece (first test piece)
44 Second specimen (second specimen)
T Wood to be evaluated (wood to be evaluated)

Claims (3)

The resistance value when a drill penetrates the target wood,
A wood strength evaluation method for obtaining a compression strength value of an evaluation target wood based on a relational expression between an average resistance value at the time of drill penetration into wood and a compression strength value of wood obtained in advance.   The average resistance value at the time of penetration penetrates the drill so that it does not cross from two directions orthogonal to each other, and the two resistance values obtained are further averaged to obtain an average resistance value. The wood strength evaluation method described in 1. The compression strength value of the evaluation target wood obtained by the wood strength evaluation method according to claim 1 or 2 is compared with the reference compression strength value of the wood, and the structure having the evaluation target wood is repaired. A repair diagnosis method for structures that diagnoses the necessity of maintenance.

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