JP2015090339A - Method of analyzing yield strength of wooden framework member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of analyzing the yield strength of a wooden framework member for easily and accurately calculating an area where there have been a discoloration part and an increase in temperature, to efficiently analyze the yield strength including buckling yield strength of a wooden framework member after combustion.SOLUTION: There is provided a method of analyzing yield strength by a computer 11 having an image analysis program incorporated therein, the method including a yield strength analyzing step S4 of tracing a carbonized part 20a of a cross section 20 of a wooden framework member after combustion on an image of the cross section 20 on a display 14 to analyze the yield strength of the wooden framework member after combustion having the possessing yield strength reduced due to heating during the combustion. The yield strength analyzing step S4 includes calculating overlapping parts 23a and 23b where the cross section 20a after combustion is overlapped with an area formed by the locus of a circle having a predetermined radius and centering a tracing point, which moves while tracing, and analyzing the overlapping parts 23a and 23b, assuming that the possessing yield strength of the overlapping parts is reduced due to heating during the combustion, by using the assumed Young's modulus, which is obtained by multiplying the Young's modulus by a coefficient of reduction.

Description

  TECHNICAL FIELD The present invention relates to a method for analyzing the strength of a wooden frame member, and in particular, to analyze the strength of a wooden frame member such as a column and a beam after combustion by a computer incorporating an image analysis program. Regarding the method.

  When the surface of wood is ignited and carbonized, a carbonized layer is formed in the combustion part. This carbonized layer is provided with a heat insulating property that blocks the supply of oxygen necessary for burning wood and protects a healthy portion inside the carbonized layer from high-temperature heating. In addition, the thermal conductivity of wood itself is as small as about 1/10 of concrete, and wood contains a considerable amount of water even in an air-dried state. It will take a considerable amount of time.

  Furthermore, wood has been found to vary such that when its surface is subjected to constant heating, the internal temperature rise decreases from the surface side toward the center side, and as the internal temperature rises, It has also been found that the structural yield strength decreases (for example, see Non-Patent Document 1).

  On the other hand, for example, the fireproof performance of a wooden bearing wall is evaluated by, for example, heat-resistant heating in a state where a predetermined load is loaded on a test wall having a height of one floor, and for a predetermined time, heat-shielding property, flame-proofing property and Although it is conducted by checking whether the non-damage property does not exceed the respective allowable limits (full-scale load heating test), the area where facilities for performing such a fire-resistant heating test can be established is limited. In addition, since the burden of the cost and labor is large, it is desired that the fireproof performance can be effectively predicted by a small experiment or calculation.

  And, for example, the fireproof performance of the wall of a timber framed wooden building is considered to be dominated by the non-damage property among the heat shielding properties, flame proof properties and non-damage properties. Since it is considered that the non-damage property of the column is governed by the buckling of the column due to flame heating, a method for predicting the fireproof performance by a compression test using only the column as a test body has been studied. As such a method, for example, a specimen of a column that reproduces the mechanical state after fire-resistant heating, which is expected for non-damage during fire-resistant heating of a wooden wall, is prepared, and obtained by a compression experiment on the created specimen. From the obtained results, a method for predicting the buckling load of a true wall column for 30 minutes for fire prevention and 45 minutes for quasi-fire resistance is proposed by applying a certain coefficient to the buckling load formula of Euler. (For example, refer nonpatent literature 2).

  However, in the prediction of the fire resistance of the wooden wall of Non-Patent Document 2, for example, assuming that the carbonization depth of 45 minutes after heating is 30 mm, the cross section corresponding to the carbonization depth is cut from the three directions of the heating surface front and both side surfaces. The temperature distribution inside the burning column is set for each depth from the charring end (the outermost part on the non-carbonized heating side), and the Young's modulus in each range surrounded by the set temperature distribution isotherm By replacing the remaining rate with the decrease in the cross-sectional area of each cross section, the cross section of the test specimen is designed assuming that the column is burned. However, if there is a burning in the column that is different from what is assumed in the actual full-scale load heating test, it is judged whether the prediction is correct, whether the test result is acceptable or not. hard. In addition, when assuming the state of incineration during refractory heating at the beginning of the calculation, it was usual to simplify the carbonization position and temperature rise position and set it to the disadvantaged model for safety reasons. It was difficult to understand the actual ability value of the sensor, and it was difficult to accurately verify the non-damage.

  On the other hand, the applicant of the present application does not perform a full-scale load heating test, but performs a small-scale combustion test on a wood specimen constituting a wooden frame member, and performs accurate non-damage verification. Has developed a method for verifying the non-damage of a wooden frame member that can be efficiently performed (see, for example, Patent Document 1).

  The non-damage verification method for wooden frame members of Patent Document 1 is for verifying the non-damage after burning of wooden frame members such as columns and beams. Conducting a heating experiment, grasping the discoloration status of wood at a predetermined temperature in advance, and grasping in advance the correlation between the increase in internal temperature and the decrease in structural strength of the wood material of the wooden frame member In addition, after performing a combustion test on the wood specimen constituting the wooden frame member, in the predetermined cross section of the specimen, the carbonized portion is removed, and the temperature rise range is set from the measured discoloration portion of the wood. From the above-mentioned correlation, the non-damage property of the wooden frame member after combustion is verified in consideration of the decrease in structural strength due to the increase in internal temperature.

"Fireproof design of wooden buildings" by Nakamura Ryoichi and Makoto Yamada, published in October 1998 “Prediction of fireproof performance of wooden wall” Mariko Shimizu et al., Architectural Institute of Japan, 611 P165-170, January 2007, published by Architectural Institute of Japan

Japanese Patent No. 5242500

  However, in the non-damage verification method of the wooden frame member of Patent Document 1, in the predetermined cross section of the test body after performing the combustion test, the region of the discolored portion for setting the temperature rise range, the carbonization and the discoloration However, the work of identifying the area where the temperature is considered to have risen is mainly performed manually. For this reason, even if it is a wooden frame member of the same cross-sectional shape, since the shape of the carbonized part differs with each wooden frame member according to the state of incineration at the time of combustion, each wooden frame member Therefore, it takes a lot of time and labor to accurately identify the discolored area and the area where the temperature is likely to rise.

  In the cross section after burning of the wooden frame member, the present invention can easily change the discolored area for setting the temperature rise range or the area where the temperature rise is considered, without much labor. In addition, it is possible to calculate the strength of a wooden frame member such as a column and a beam after combustion, and to efficiently analyze the strength of the wooden frame member such as a column and a beam. It is an object to provide a storage medium storing an analysis program.

  The present invention is a proof stress analysis method for analyzing the proof strength (including buckling proof strength and bending proof strength) of a wooden frame member such as a column or a beam by a computer incorporating an image analysis program. An image reading step for reading an image of a cross section of the wooden frame member together with a background of an opposite color (including complementary color and black), and a cross section of the wooden frame member read together with the background and displayed on the display The image placement step of placing the image in a reference frame set on the display in a state matched with the scale in the reference frame, and the wooden frame member placed in the reference frame on the display By tracing the carbonized part in the cross section with respect to the image of the cross section, the wooden frame member including the part whose retained yield strength has been reduced by heating at the time of combustion is obtained. A strength analysis step for analyzing the structure, wherein the strength analysis step includes a region formed by a locus of a circle having a predetermined radius centered on a tracing point that moves while tracing, and a cross section of the wooden frame member. Calculate the overlapping part, which is the cross-sectional area where the two overlap, and assume that the retained yield strength of this overlapping part is reduced by heating during combustion, and analyze it using an assumed Young's modulus multiplied by a predetermined reduction factor Thus, the above object is achieved by providing a method for analyzing the strength of a wooden frame member for calculating the strength after burning of the wooden frame member.

  And the yield strength analysis method of the wooden frame member of the present invention performs image processing on the cross-sectional image of the wooden frame member arranged in the reference frame on the display in the image arrangement step, A cross-sectional sampling display step for displaying the cross section of the wooden frame member excluding the background on the display, and a calculation of the cross section of the wooden frame member displayed on the display in the cross-sectional sampling display step in the strength analysis step. It is preferable that a proof stress reduction unit display step for displaying the overlapped portion.

  Further, in the yield strength analysis method for a wooden frame member according to the present invention, in the yield strength analysis step, an area defined by a locus of a circle having a first radius centered on a tracing point that moves while tracing, Calculating the first overlapping portion where the cross-section overlaps, and calculating the second overlapping portion where the region of the circle of the second radius larger than the first radius overlaps the cross-section of the wooden frame member; The wooden bearing shaft is analyzed by using the assumed Young's modulus obtained by multiplying the Young's modulus by the first reduction factor or the second reduction factor, assuming that the retained yield strength of these parts is reduced by heating during combustion. It is preferable to calculate the yield strength of the assembled member after combustion.

  Further, in the strength analysis method for a wooden frame member according to the present invention, the first radius is 5 mm, the second radius is 30 mm, the first reduction factor is 0.5, The reduction factor of 2 is preferably 0.8.

  Furthermore, in the yield analysis method of the wooden frame member according to the present invention, in the yield analysis step, an equivalent cross-section neutral axis is calculated with respect to a cross section of the wooden frame member after combustion including a portion where the retained yield strength is reduced. Preferably, a neutral axis calculation step is included.

  Moreover, this invention achieves the said objective by providing the yield analysis program of the wooden frame member which makes a computer perform each step in the yield strength analysis method of the above-mentioned wooden frame member.

  Furthermore, the present invention achieves the above object by providing a computer-readable storage medium storing the above-described wooden frame member strength analysis program.

  According to the strength analysis method of a wooden frame member, the strength analysis program of a wooden frame member, or the storage medium storing the analysis program according to the present invention, a lot of labor is required in the cross section of the wooden frame member after combustion. Therefore, it is possible to easily and accurately calculate the discolored area for setting the temperature rise range and the area where the temperature rise is thought to have occurred. The yield strength after combustion of the member can be analyzed efficiently.

It is a system configuration figure explaining a computer system containing a computer for enforcing a yield strength analysis method of a wooden frame member concerning a preferred embodiment of the present invention. It is a flowchart explaining each step of the strength analysis method of the wooden frame member which concerns on preferable one Embodiment of this invention. It is the picked-up image of the cross section of the wooden framework member after a combustion image | photographed with the background used as an opposite color. It is a display figure on a display explaining the image of the section of the wooden frame member read at the image reading step. It is a display figure on a display explaining an image arrangement | positioning step. It is a display figure on a display explaining a section extraction display step. It is a display figure on a display explaining the situation which traces the carbonized part with respect to the image of the section of a wooden frame member in a proof stress analysis step. It is a display figure on a display explaining a proof stress reduction part display step. It is a display figure on a display explaining a neutral axis calculation step. It is a flowchart explaining the substep in a yield strength analysis step. It is a chart explaining the correlation with the raise of the internal temperature in the wood of the raw material of a wooden frame member, and the fall of structural yield strength (residual yield strength).

  The strength analysis method for a wooden frame member according to a preferred embodiment of the present invention is implemented using a computer system 10 including a computer 11 having a database 12 as shown in FIG. The proof stress analysis method of this embodiment is a buckling proof strength, particularly as a proof strength after burning of a wooden framing member such as a column or a beam, by the non-damage verification method for wooden framing members described in Patent Document 1 described above. When analyzing, it is considered that there was a discoloration area for setting the temperature rise range and the temperature rise without much labor for the cross section after burning of the collected wooden frame member This method is employed as a method for calculating the partial area easily and accurately.

  Here, the computer 11 constituting the computer system 10 is known as a computer having a database 12, and the database 12 is a CPU, ROM, RAM, I / F, storage means, input means, display means, output means. Etc.

  The CPU of the computer 11 controls the overall operation of the database 12 while using the RAM as a work area in accordance with a control program incorporated in the ROM. In addition, since various data analysis programs and other computer programs are incorporated in the hard disk, the CPU analyzes the buckling strength after burning of the wooden frame member and various other types as described later. Processing can be performed. The storage unit of the database 12 stores, for example, image data captured using a shooting unit such as a digital camera or a scanner in the data storage unit 13 and reads out the stored image data to analyze data. It can be used for other processing. The computer 11 is connected to a display unit 14 including a display, a printing unit 15 including a printer, an input unit 16 including a keyboard and a mouse, and the like.

  In the present embodiment, the CPU 11 of the computer 11 incorporates a later-described strength analysis program including a known image analysis program as a data analysis program. Thereby, various analyzes can be performed using the image data (see FIG. 3) of the cross section 20 of the wooden frame member after combustion including the background 21 of the opposite color stored in the data storage unit 13. It is like that.

  The method of analyzing the proof stress of the wooden frame member according to the present embodiment is, for example, the proof strength of analyzing the buckling proof strength as the proof strength after burning of the wooden frame member such as a column or a beam by the computer 11 incorporating the image analysis program. 2. An analysis method for reading an image of a cross section 20 (see FIG. 3) of a wooden frame member after combustion together with a background 21 of an opposite color (including complementary colors and black) as shown in FIG. In step S1 (see FIG. 4), the image of the cross section 20 of the wooden frame member read together with the background 21 and displayed on the display 14 is displayed in the reference frame 17 set on the display 14 in the reference frame 17. For the image placement step S2 (see FIG. 5) for placement in a state matched with the scale of FIG. 5 and the image of the cross section 20 of the wooden frame member placed in the reference frame 17 on the display 14, the cross section 20 By tracing the carbonized portion 20a in the wood, the strength analysis step S4 for analyzing, for example, the buckling strength after combustion of the wooden frame member including the portion whose retained strength is reduced by heating during combustion (see FIG. 7) In the proof stress analysis step S4, a cross section in which a region formed by a circular locus having a predetermined radius centering on a tracing point that moves while tracing and a cross section 20 of the wooden frame member after combustion overlap. The overlapping portions 23a and 23b, which are regions, were calculated (see FIG. 8), and the retained strength of the overlapping portions 23a and 23b was reduced by heating during combustion, and the Young's modulus was multiplied by a predetermined reduction factor. By analyzing using the assumed Young's modulus, the yield strength after burning of the wooden frame member is calculated.

  Further, the method for analyzing the strength of the wooden frame member according to the present embodiment performs image processing on the image of the cross section 20 of the wooden frame member arranged in the reference frame 17 on the display 14 in the image arrangement step S2. Then, a section extraction display step S3 (see FIG. 6) for displaying the cross section 20 of the wooden frame member excluding the background 21 on the display 14, and the wooden frame displayed on the display 14 in the section extraction display step S3. The cross section 20 of the member includes a strength reduction portion display step S5 (see FIG. 8) for displaying the overlapping portions 23a and 23b calculated in the strength analysis step S4.

  In the present embodiment, prior to starting the image analysis program incorporated in the computer 11 or the proof stress analysis program, a known digital camera or scanner capable of creating image data is used as an imaging unit, and FIG. As shown, a cross-section 20 of the sampled wooden framing member after combustion is photographed with a background 21 of the opposite color. That is, a predetermined cross section 21 of the wooden shaft member after combustion is photographed with a light blue background as a background, for example. In the present embodiment, a square arrangement frame 22 having a size of one side which is preferably the same size as the square reference frame 17 set on the display 14 in the image arrangement step S2 is used as a wooden frame. A cross section 20 of the wooden frame member is photographed together with the arrangement frame 22 and the background 21 in a state of being disposed at a position surrounding the cross section of the member. The image data of the cross section 20 of the wooden frame member obtained by the photographing means is read into the computer 11 in the image reading step S1 via a wired or wireless communication line or an external storage medium.

  In the image reading step S1, after the image analysis program and the strength analysis program are started, the burned wooden frame member including the arrangement frame 22 and the background 21, which has been photographed using photographing means such as a digital camera or a scanner, is captured. The image data of the cross section 20 is read into the computer 11 via a wired or wireless communication line or an external storage medium. The read image data of the cross section 20 of the wooden shaft member after combustion is stored in the data storage unit 13 and displayed on the display 14 as shown in FIG. By performing an operation to be described later on the cross section 20 of the burned wooden frame member displayed on the display 14 by using an input unit 16 such as a keyboard or a mouse, the wooden frame frame is obtained in the proof stress analysis step S4. The buckling strength after combustion of the member is calculated.

  In the image placement step S2, as shown in FIG. 5, for example, a square reference frame 17 with a clear side length is set and displayed on the display 14 by the function of the strength analysis program. Further, the position and size of the image data of the cross-section 20 of the burned wooden frame member that is read in the image reading step S1 and displayed on the display 14 are adjusted so that the arrangement frame 22 exactly overlaps the reference frame 17. By doing so, alignment is performed so that the image of the cross section 20 is displayed in the approximate center of the reference frame 17. As a result, the scale of the image of the cross section 20 of the wooden frame member after combustion displayed on the display 14 matches the scale inside the reference frame 17.

  Here, the reference frame 17 set on the display 14 is not necessarily provided by displaying a square or other shape frame on the screen, and the entire screen of the display 14 is set to a predetermined scale, The entire screen can be used as the reference frame 17. In this case, for example, a reference line segment having a known length or shape between two points at both ends is set and displayed on the display 14, and the cross section 20 of the wooden framework member after combustion is similar to the reference line segment. The position of the image data is such that the captured line segment exactly overlaps the reference line segment on the display 14 displaying such image data. By adjusting the size, the scale of the reference frame 17 by the entire screen of the display 14 and the scale of the image of the cross section 20 of the wooden frame member after combustion can be matched.

  Further, the buckling strength analysis method for the wooden frame member of the present embodiment includes a section extraction display step S3, and this section extraction display step S3 is performed prior to the strength analysis step S4. . That is, in the cross-section sampling display step S3, for example, binarization processing is performed on the image data of the cross-section 20 of the wooden frame member after combustion read together with the background 21 having the opposite color by the function of the image analysis program. Thus, as shown in FIG. 6, it is possible to easily obtain a sampling image 20 ′ in which only the cross section 20 of the burned wooden frame member is extracted. The extracted image 20 ′ of the cross section 20 of the wooden frame member after combustion is preferably displayed on the display 14 together with image data before performing the binarization process.

  In the extracted image 20 ′ extracted from the section 20 of the wooden frame member after combustion, which is displayed on the display 14 in the section extraction display step S3, the combustion before the binarization processing is performed in the proof stress analysis step S4. With respect to the image data of the cross section 20 of the later wooden frame member, as the carbonized portion 20a is traced by the trace line 24, the trace line 24 'of the traced portion is the same as shown in FIG. Can be displayed as follows. Further, in the extracted image 20 'in which only the cross section 20 of the wooden shaft member after combustion is extracted, the carbonized portion 20a' can be traced by the trace line 24 '.

  Further, in the present embodiment, for example, by finishing the operation of tracing the carbonized portions 20a and 20a ′, and clicking on the “setting completed” portion on the display 14, for example, by the proof stress reducing portion display step S5, The area calculated by the locus of a circle having a predetermined radius centered on a tracing point that moves while tracing the carbonized portions 20a and 20a ′ and the cross-sections 20 and 20a ′ of the wooden frame members calculated in the yield strength analysis step S4. As shown in FIG. 8, the overlapping portions 23a and 23b, which are overlapping cross-sectional areas, can be displayed in a color-coded state on the extracted image 20 ′.

  In the present embodiment, as will be described later, calculation is performed as a first overlapping portion 23a where a region of a circular path having a first radius centering on a tracing point that moves while tracing and a cross section 20 of the wooden frame member overlap. There is no carbonization or discoloration calculated as the second overlapping portion 23b in which the discolored portion, the region by the locus of the circle of the second radius larger than the first radius, and the cross section of the wooden frame member overlap. A portion that is thought to have risen in temperature is displayed in a color-coded state.

  In this embodiment, in the proof stress analysis step S4, the carbonized portion of the cross section 20 is traced with respect to the image of the cross section 20 of the wooden frame member arranged in the reference frame 17 on the display 14. Thus, for example, the buckling strength after combustion is analyzed for the wooden frame member including the portion where the retained strength is reduced by heating during combustion. That is, in the proof stress analysis step S4, an overlapping portion 23a, which is a cross-sectional area where a region of a circular locus having a predetermined radius centered on a tracing point that moves while tracing and a cross-section 20 of the wooden frame member after combustion overlaps. 23b is calculated (see FIG. 8), and the retained strength of the overlapping portions 23a and 23b is assumed to be reduced by heating during combustion, and is analyzed using an assumed Young's modulus obtained by multiplying the Young's modulus by a predetermined reduction factor. By doing so, the buckling strength after combustion of the wooden frame member is calculated.

  In the present embodiment, as shown in FIG. 10, the proof stress analysis step S4 includes, as sub-steps, a temperature distribution setting step S4a, an intensity distribution setting step S4b, an equivalent cross section calculation step S4c, and a damage damage verification step S4d. The neutral shaft calculation step S4e is included, and by these sub-steps, for example, the buckling strength after combustion is analyzed for the wooden frame member including the portion where the retained strength is reduced by heating during combustion. Can be done. These sub-steps are performed by a yield strength analysis program incorporated in the computer 11.

  In the temperature distribution setting step S4a, the carbonized portions 20a and 20a 'in the cross sections 20 and 20' are applied to the images of the cross sections 20 and 20 'of the wooden frame member disposed in the reference frame 17 on the display 14. By tracing, an overlapping portion 23a, 23b, which is a cross-sectional area where a region of a circle having a predetermined radius centered on a tracing point that moves while tracing and a cross-section 20, 20 ′ of the wooden frame member overlap, is formed. Calculate.

  Here, in the present embodiment, as described in Patent Document 1 described above, for example, prior to performing a combustion test on a specimen of wood constituting a wooden frame member, the raw material wood of the wooden frame member A heating experiment is performed on the wood to grasp in advance the discoloration of the wood at a predetermined temperature. That is, cypress, cedar, bay pine, or SFP is preferably cut as a discoloration test piece having a width of about 105 mm, a thickness of 52 mm, and a length of about 500 mm, for example, and placed inside an electric furnace. For example, at a temperature of 100 ° C., 150 ° C., 180 ° C., 220 ° C., and 250 ° C., for example, after heating and discoloration for about 2 to 7 hours until the heating temperature and the wood temperature become equal, the color is taken out from the electric furnace. . These taken-out discoloration test specimens are used as color samples for setting the temperature rise range from the discoloration portion in a predetermined cross section of the test specimen after performing a combustion test described later.

  Further, in the present embodiment, for example, prior to performing a combustion test on a wood specimen constituting a wooden frame member, as a factor of the rise in internal temperature in the wood of the raw material of the wooden frame member and structural strength For example, a correlation with a decrease in Young's modulus is grasped in advance. The correlation between the increase in internal temperature and the decrease in Young's modulus in wood can be easily grasped from, for example, the content described in Non-Patent Document 1 described above. For example, from the results of the elastic modulus (Young's modulus) and the residual rate of fracture load (%) described in Table 3-3 on page 40 of Non-Patent Document 1 above, the internal temperature and the residual yield strength as shown in FIG. And get a relationship.

  Then, the approximate line shown in FIG. 11 can be drawn from the relationship between the internal temperature and the residual yield strength shown in FIG. 11, and thereby, the relationship between the cross-sectional position and the Young's modulus as shown in Table 1 is obtained. Can do.

  In the relationship between the cross-sectional position and the Young's modulus shown in Table 1, a discolored portion (a portion that is not carbonized but has a color difference from a healthy portion. According to the color sample from the discoloration test specimen described above, for example, visually Discoloration that can be discriminated with occurs in the range of about 150 to 180 ° C. and often has a yellow or brown color.) Is 0-5 mm from the carbonized end (cross-sectional edge where the carbon of the carbonized portion is dropped). It is an area. In this region, the assumed residual proof stress is reduced to 50%, and the assumed Young's modulus (the assumed Young's modulus obtained by multiplying the Young's modulus by a predetermined reduction factor) is 0.5E.

  In addition, according to the above-mentioned Non-Patent Document 1, the situation of variation in internal temperature when wood is heated for a certain period of time is known, and for example, when heating according to the standard heating curve of ISO834 is directly received for 30 to 45 minutes In the region within about 30 mm including the discolored portion from the carbonization end, a temperature rise is recognized, and the value is larger as the carbonization end is closer. In this region, the portion excluding the discolored portion is a portion where there is no carbonization or discoloration but is considered to have risen in temperature. In this portion where there is no carbonization or discoloration but is thought to have risen in temperature, the residual proof stress is It is reduced to 80%, and an assumed Young's modulus (an assumed Young's modulus obtained by multiplying the Young's modulus by a predetermined reduction factor) is 0.8E.

  Therefore, in the present embodiment, the first radius of 5 mm corresponding to the above-described discolored portion is used as a predetermined radius centered at the trace point for calculating the overlapping portions 23a and 23b with the cross section 20 of the wooden frame member. A radius and a second radius of 30 mm corresponding to a portion where there is no carbonization or discoloration as described above but is considered to have increased in temperature are used. Then, for example, by tracing the carbonized ends of the portions 20a and 20a ′ carbonized by the pointer on the display 14, an area formed by a locus of a circle having a first radius of 5 mm centered on a tracing point that moves while tracing. The discolored portion, which is a cross-sectional area overlapping with the cross-section 20 of the wooden frame member, is automatically calculated as the first overlapping portion 23a by a predetermined calculation formula by an image analysis program incorporated in the computer 11. Further, it is considered that there was no carbonization or discoloration, but there was a temperature rise, which is a cross-sectional area where the area of the circle of the second radius of 30 mm larger than the first radius overlaps the cross section 20 of the wooden frame member. The portion is automatically calculated as the second overlapping portion 23b by a predetermined calculation formula by an image analysis program incorporated in the computer 11. These overlapping portions 23a and 23b are displayed in a color-coded state as the first overlapping portion 23a and the second overlapping portion 23b on the extracted image 20 ′ displayed on the display 14 by the above-described strength reduction portion display step S5. (FIG. 8).

  Here, for example, when tracing the carbonized ends of the carbonized portions 20a and 20a ′ by the pointer on the display 14, be careful not to trace the portion shifted to the inside of the cross section 20 or 20 ′ from the carbonized ends. There is a need to. That is, the trajectory by the circle of the first radius and the trajectory by the circle of the second radius define the inner edge of the cross-sectional area that overlaps the cross-section 20 of the wooden frame member, and inside the carbonized end. When the shifted portion is traced, a cross-sectional area overlapping with the cross-section 20 of the wooden frame member is picked up to that extent. For this reason, it is impossible to accurately calculate a discolored portion or a portion that has no carbonization or discoloration but is considered to have a temperature rise. On the other hand, when the part shifted outside the carbonized end is traced, the inner edge of the cross-sectional area overlapping the cross section 20 of the wooden frame member is corrected by retracing along the carbonized end. Therefore, it is possible to accurately calculate a discolored portion or a portion that is considered not to be carbonized or discolored but has a temperature rise.

  In the strength distribution setting step S4b of the proof stress analysis step S4, the temperature distribution of the discolored portion calculated in the temperature distribution setting step S4a, the portion where there is no carbonization or discoloration but considered to have risen in temperature, and the wooden frame member are used. The strength distribution is set by comparing with the high-temperature strength of the constituent wood. That is, according to the relationship between the internal temperature and the residual strength shown in FIG. 11 obtained from the above-mentioned Non-Patent Document 1, it is clear that the structural strength of wood decreases as the temperature rises. By matching with the temperature rise range set in the distribution setting step S4a, it is possible to set the strength distribution in the cross section 20 of the wooden frame member after combustion.

  In the equivalent cross section calculation step S4c of the proof stress analysis step S4, the cross-sectional area is determined by changing the strength of the discolored portion in the cross section 20 of the wooden frame member after combustion, or the portion considered to have a temperature rise although there is no carbonization or discoloration. The equivalent cross-section is calculated by substituting for the drop in the total. Here, the strength of the material is generally expressed by a stiffness EI using an elastic modulus (Young's modulus) E and a secondary moment of inertia I. For example, in the buckling load equation of Euler's long column, the buckling load equation Is proportional to EI, so non-damage can be assessed by the magnitude of this EI. Therefore, as described above, the assumed overlapping Young's modulus E obtained by multiplying the Young's modulus E by a predetermined reduction factor of the first overlapping portion 23a, which is a discolored portion, is 0.5E. Since the assumed Young's modulus obtained by multiplying the Young's modulus E by a predetermined reduction coefficient of the second overlapping portion 23b, which is considered to be a portion, is 0.8E, by analyzing using these assumed Young's modulus, For example, it is possible to easily calculate, for example, the buckling strength after burning of the wooden frame member by a predetermined calculation formula by an image analysis program incorporated in the computer 11.

Further, the rectangular cross-section, a rigid ^{EI = Ebh 3/12 (b} = weak axis direction width, h = strong axis direction width), when all of the cross-section considered a collection of small rectangular cross-section, each minute section Thus, the assumed Young's modulus decreased due to the temperature rise can be replaced with a decrease in the respective cross-sectional areas bh. As for the cross-sectional portion whose strength has been reduced by the temperature rise in this way, it is possible to obtain a mechanically equivalent equivalent cross-section if the cross-sectional area is reduced and integrated.

In the damage damage verification step S4dc of the proof stress analysis step S4, the non-damage property is verified based on the cross-sectional secondary moment of the equivalent cross-section. That is, by calculating the second moment I _t of equivalent sectional, the, size, distance between the loading point and the neutral axis, that from the relationship of the edge stresses, etc., to evaluate the non-damaging diverse members It becomes possible. Note that the 30-minute fire structure wooden Makabe granulation or quasi fireproof structure 45 minutes, due to the presence of the prediction equation of the above equation (1), by inputting a I _t to _50% I _k, directly during heating It becomes possible to know the buckling load of the wooden frame member that can withstand the load.

  In the neutral axis calculation step S4e of the proof stress analysis step S4, an image analysis program incorporated in the computer 11 is used for the equivalent cross section of the wooden frame member after combustion obtained in the equivalent cross section calculation step S4c of the proof stress analysis step S4. A predetermined calculation formula is executed to calculate the equivalent cross-section neutral axis 25a in the weak axis direction. As shown in FIG. 9, the calculated equivalent cross-section neutral shaft 25a is superimposed on the extracted image obtained by extracting only the cross-section 20 ′ of the wooden frame member after combustion, for example, and the total remaining value cross-section neutral shaft 25b in the weak axis direction. Is displayed.

  Each sub-step of the proof stress analysis step S4 described above is executed by, for example, clicking on a “predicted buckling load calculation” portion on the display 14.

  And according to the yield strength analysis method of the wooden frame member of the present embodiment having the above-described configuration, in order to set the temperature increase range in the cross section 20 after the burning of the wooden frame member without requiring much labor. It is possible to easily and accurately calculate the area of the discolored part and the part of the part considered to have risen in temperature, such as the buckling strength after burning of wooden frame members such as columns and beams. The yield strength can be analyzed efficiently.

  That is, the strength analysis method of the wooden frame member of the present embodiment is executed by the computer 11 in which the image analysis program is incorporated, and the carbonized portion 20a of the image of the cross section 20 of the wooden frame member arranged on the display 14 is obtained. Is included, and a wooden frame member including a portion whose retained yield strength has been reduced by heating during combustion includes a yield strength analysis step S4 for analyzing the yield strength after combustion. In this yield strength analysis step S4, Then, overlapping portions 23a and 23b, which are cross-sectional regions where the region of the circular trajectory with a predetermined radius centered on the moving trace point and the cross-section 20 of the wooden frame member after combustion overlap, are calculated (see FIG. 8). Assuming that the retained strength of the overlapping portions 23a and 23b is reduced by heating during combustion, the Young's modulus is multiplied by a predetermined reduction factor. By analyzing using an assumed Young's modulus, and calculates the strength of the buckling strength or the like after the combustion of wood shaft assembly member.

  Therefore, according to the present embodiment, the discolored portion, which is the discolored portion, is moved around the tracing point, which is a discolored portion, by a simple operation of tracing the carbonized portion 20a of the image of the cross section 20 of the wooden frame member. The first overlapping portion 23a where the region of the circular trajectory of the radius 1 and the cross section 20 of the wooden frame member overlap, and the second radius of the second radius, which is a portion where there is no carbonization or discoloration but is thought to have risen in temperature. Since the second overlapping portion 23b where the region of the circular locus overlaps with the cross section of the wooden frame member can be automatically calculated easily, the buckling strength after burning of the wooden frame member such as a column or a beam It is possible to efficiently analyze the proof stress.

  Moreover, the strength analysis method of the wooden frame member according to the present embodiment can be easily implemented by a strength analysis program of the wooden frame member that causes the computer to execute the above steps.

  Furthermore, the strength analysis program for the wooden frame member can be easily incorporated into the computer via a computer-readable storage medium storing the strength analysis program.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the strength analysis method for a wooden frame member according to the present invention does not necessarily include a section extraction display step, a strength reduction portion display step, and a neutral axis calculation step. In addition, it is not always necessary to calculate both the first overlapping portion due to the circle with the first radius and the second overlapping portion due to the circle with the second radius. It is also possible to calculate the yield strength. The radius of the circle centered on the tracing point that moves while tracing is not necessarily 5 mm or 30 mm, and the Young's modulus reduction coefficient is not necessarily 0.5 or 0.8. The proof stress analyzed by the proof stress analysis method of the present invention is the proof strength of other post-combustion wooden frame members, such as buckling proof strength, bending proof strength after burning of wooden frame members such as columns and beams. May be.

DESCRIPTION OF SYMBOLS 10 Computer system 11 Computer 12 Database 13 Data storage part 14 Display (display part)
DESCRIPTION OF SYMBOLS 15 Printing part 16 Input part 17 Reference | standard frame 20, 20 'Section 20a, 20a' of the wooden frame member after combustion Carbonized part 21 Background 22 Arrangement frame 23a 1st overlap part (discoloration part)
23b Second overlapping portion (there is no carbonization or discoloration, but the portion considered to have risen in temperature)
24, 24 'Trace line 25a Equivalent section neutral axis 25b Total residual value section neutral axis

Claims (7)

A strength analysis method for analyzing the strength of a wooden frame member such as a column or beam after burning by a computer with an image analysis program incorporated therein,
An image reading step for reading an image of a cross section of the wooden frame member after burning together with a background having an opposite color;
An image arrangement step for arranging an image of a cross section of the wooden frame member read together with the background and displayed on a display in a reference frame set on the display in a state of being matched with a scale in the reference frame. When,
The image of the cross section of the wooden frame member arranged in the reference frame on the display includes a portion in which the holding strength is reduced by heating during combustion by tracing the carbonized portion in the cross section. About the wooden frame member, comprising a proof stress analysis step for analyzing the proof strength after combustion,
In the proof stress analysis step, an overlapping portion which is a cross-sectional region in which a region of a circle with a predetermined radius centering on a tracing point moving while tracing and a cross-section of the wooden frame member overlap is calculated, and the overlapping portion Assuming that the proof strength of the wood frame is reduced by heating during combustion, the post-combustion proof strength of the wooden frame member is calculated by analyzing it using an assumed Young's modulus obtained by multiplying the Young's modulus by a predetermined reduction factor. Strength analysis method for wooden frame members. Image processing is performed on an image of a cross section of the wooden frame member arranged in the reference frame on the display in the image arrangement step, and the cross section of the wooden frame member excluding the background is displayed on the display. A section sampling display step to be displayed;
The wooden shaft according to claim 1, further comprising: a proof stress reducing unit displaying step for displaying the overlap portion calculated in the proof stress analyzing step in a cross section of the wooden framing member displayed on the display in the cross sectional sampling display step. Strength analysis method for assembled members.   In the yield strength analysis step, a first overlapping portion where a region of a circle of a first radius centered on a tracing point that moves while tracing and a cross section of the wooden frame member overlap is calculated, The second overlapping portion where the region of the circular locus of the second radius larger than the radius and the cross section of the wooden frame member overlap was calculated, and the retained strength of these portions was reduced by heating during combustion. The post-combustion proof stress of the wooden frame member is calculated by analyzing using the assumed Young's modulus obtained by multiplying the Young's modulus by the first reduction factor or the second reduction factor. The yield strength analysis method of the wooden frame member described in 1.   4. The first radius is 5 mm, the second radius is 30 mm, the first reduction factor is 0.5, and the second reduction factor is 0.8. Yield strength analysis method for wooden frame members.   The neutralization axis calculation step of calculating an equivalent cross-section neutral axis with respect to the cross section of the wooden framing member after combustion including the portion where the retained proof stress is reduced in the proof stress analysis step. A method for analyzing the yield strength of the wooden frame member according to the item.   A strength analysis program for a wooden frame member that causes a computer to execute each step in the method for analyzing the strength of a wooden frame member according to any one of claims 1 to 5.   A computer-readable storage medium storing the strength analysis program for a wooden frame member according to claim 6.