JP6052737B2 - Crack detection method and crack detection apparatus for steel slab - Google Patents

Description

  The present invention relates to a crack detection method and a crack detection apparatus for a steel deck.

  A steel slab constituting a floor plate portion of a bridge generally includes a deck plate and ribs arranged on the lower surface of the deck plate to reinforce the deck plate. As the rib, a long steel material such as a U-rib having a U-shaped cross section is used. The U rib has a pair of vertical plates that are separated from each other, and the upper ends of the vertical plates are welded to the lower surface of the deck plate along the longitudinal direction of the ribs.

  Here, the welded portion between the deck plate and the U-rib may crack along the extending direction of the welded portion due to the long-term use of the bridge.

  Therefore, various detection methods have been proposed in the past in order to detect the presence or absence of cracks in the welded portion between the deck plate and the U rib constituting the floor plate.

  For example, in the crack detection method described in Patent Document 1, an electromagnetic induction coil is installed on the deck plate of the steel floor slab in order to inspect the crack portion of the steel floor slab, and the U-rib in the deck plate is formed by electromagnetic induction heating. A wide area (eg, a circular area corresponding to a circular coil) is directly heated, and at the same time, a temperature measurement device measures the temperature distribution of the heated part of the deck plate.

  The heat of the deck plate heated by electromagnetic induction is conducted through the welded part from the deck plate to the U-rib welded to the lower surface, but if there is a crack or break in the welded part, Heat is hardly conducted to the lower end of the U rib. Therefore, a difference occurs in the temperature distribution of the inspection site depending on whether there is a crack or not. As a result, it is possible for the evaluator to visually observe this temperature distribution and discriminate the presence or absence of a crack, thereby finding a crack.

JP 2011-242362 A

  In the crack detection method described above, it is necessary to heat the deck plate of the steel deck by electromagnetic induction, and at the same time, obtain the temperature distribution in a wide range by a temperature measuring device. Therefore, it takes time and labor to acquire temperature distribution data.

  In addition, since it is necessary for the evaluator to visually observe all acquired temperature distributions to determine the presence or absence of cracks, there is a problem that it is difficult to quickly determine the cracks.

  Further, since the acquired temperature distribution relates to a wide area including the welded portion, the capacity of the image data increases. For this reason, there is a problem that it is difficult to automatically determine cracks because the processing apparatus is heavily burdened when performing image analysis in order to automatically determine the presence or absence of cracks.

  The present invention has been made in view of the above circumstances, and a method and apparatus for detecting a crack in a steel deck that can easily and quickly determine the presence or absence of a crack in a welded portion of a steel deck. The purpose is to provide.

In order to solve the above problems, the method for detecting cracks in a steel deck according to the present invention is a steel deck having a deck plate and a rib disposed on the lower surface of the deck plate, wherein the rib is the deck plate. A crack detection method for detecting cracks in a welded portion welded along the longitudinal direction of the rib, wherein the welded portion is a device for acquiring a temperature distribution by detecting infrared radiation energy generated from an object. The temperature sequentially acquired along the moving direction of the device by detecting the infrared radiation energy generated from the object while detecting the infrared radiation energy generated in the direction intersecting the extending direction of the welded portion while moving along the extending direction of the welding portion. A distribution acquisition step, a temperature gradient calculation step of calculating a temperature gradient in the welded portion from the acquired temperature distribution, and a calculation On the basis of the temperature gradients and is characterized in that it comprises a detection step of detecting cracks in the welded parts.

  The present invention is a rational and quick detection method specialized in automatically determining the presence or absence of cracks in a welded portion between a deck plate and a rib of a steel deck.

That is, the temperature distribution in the direction intersecting with the extending direction of the welded part is moved while moving the device that acquires the temperature distribution by detecting the infrared radiation energy generated from the object along the extending direction of the welded part. A welded portion extending in the longitudinal direction of the rib without forcibly heating the deck plate by an electromagnetic induction coil or the like by sequentially obtaining along the moving direction of the equipment by detecting infrared radiation energy generated from the object It is possible to acquire the temperature distribution in the direction intersecting with the extending direction of the welded part under substantially the same temperature condition.

  Then, it is possible to calculate a temperature gradient in the welded part from the acquired temperature distribution, and to automatically detect a crack in the welded part based on the calculated temperature gradient. Thereby, it is possible to easily and quickly determine the presence or absence of cracks in the welded portion, as compared with the case where the evaluator visually observes all acquired temperature distributions to determine the presence or absence of cracks.

  Moreover, it is preferable to perform the said temperature distribution acquisition process, when the said deck plate is heated by irradiation of sunlight.

  According to such a feature, when the deck plate is heated by sunlight irradiation in the daytime or the like, the temperature of the deck plate becomes high, and the difference in temperature gradient between when the temperature distribution in the welded portion is cracked and when there is no crack. Since it becomes clearer, it becomes possible to accurately determine the presence or absence of a crack.

Further, in the temperature distribution acquisition step, the temperature distribution in the direction intersecting with the extending direction of the welded portion at a plurality of positions separated from each other in the extending direction of the welded portion is simultaneously acquired, and in the temperature gradient calculating step, Preferably, a plurality of the temperature gradients are calculated from a plurality of temperature distributions, and in the detection step, cracks in the welded portion are detected based on the calculated temperature gradients.

  According to this feature, the temperature distribution is simultaneously acquired at a plurality of positions separated from each other in the extending direction of the welded portion, so that it is possible to acquire a plurality of temperature distributions under substantially the same temperature condition. Then, by detecting cracks in the welded part based on a plurality of temperature gradients calculated from the plurality of temperature distributions, it is possible to accurately determine the presence or absence of a crack.

  In addition, before the temperature distribution acquisition step, a determination reference value preparation step of preparing a determination reference value in advance by a ratio of the temperature gradient in the portion where the crack exists and the temperature gradient in the portion where the crack does not exist In addition, in the temperature distribution acquisition step, temperature distributions at two positions separated from each other in the extending direction of the welded portion are simultaneously acquired, and in the detection step, 2 obtained from the temperature distributions at the two locations. It is preferable to detect a crack in the welded portion by determining whether a ratio between the two temperature gradients exceeds the determination reference value.

  According to such a feature, welding is performed by determining whether or not the ratio between two temperature gradients obtained from the temperature distribution at two positions separated from each other exceeds a predetermined criterion value. Since the crack in the portion is detected, it is possible to detect the crack with high accuracy while suppressing an increase in the number of data in the temperature distribution. In addition, since two temperature distributions acquired at the same time are used for this crack detection, the number of data to be acquired can be reduced, and the speed of acquiring the temperature distribution can be improved.

  Further, as the temperature gradient, it is preferable that a difference between the highest temperature and the lowest temperature in the temperature distribution is used at least at some positions in the extending direction of the welded portion.

  According to this feature, since the temperature gradient can be easily calculated from the difference between the maximum temperature and the minimum temperature, it is possible to suppress an increase in the burden of arithmetic processing.

In addition, as the temperature gradient, a differential value relating to the amount of change in temperature with respect to the amount of change in length in the direction intersecting the extending direction of the welded part is used at least at some positions in the extending direction of the welded part. Is preferred.

According to this feature, the temperature gradient is calculated from the differential value of the temperature change with respect to the change in length in the direction intersecting with the extending direction of the welded portion , so that the temperature gradient can be calculated more accurately. As a result, it is possible to accurately detect a crack based on an accurate temperature gradient.

  The rib includes a pair of vertical plates that are spaced apart from each other and extend downward from the deck plate, and a horizontal plate that connects the lower ends of the pair of vertical plates, the upper ends of the pair of vertical plates being A closed space may be formed by the pair of vertical plates, horizontal plates, and the deck plate by being welded to the deck plate along the longitudinal direction of the ribs.

  The rib has a pair of vertical plates that are spaced apart from each other and extend downward from the deck plate, and a horizontal plate that connects the lower ends of the pair of vertical plates. In the state welded to the lower surface, a closed space is formed by the pair of vertical and horizontal plates and the deck plate constituting the rib, so that the rib cannot be welded from the inside. Accordingly, the upper ends of the pair of vertical plates of the rib are welded to the deck plate only from the outside. Therefore, the welded portion between the deck plate and the rib is very weak, and the welded portion is likely to crack. Therefore, it is possible to detect the crack in the welded portion of the rib easily and quickly by detecting the crack in the welded portion of the rib by the crack detecting method.

Further, the steel plate slab crack detecting apparatus of the present invention is a steel slab having a deck plate and a rib disposed on the lower surface of the deck plate, wherein the rib is in the longitudinal direction of the rib with respect to the deck plate. A crack detection device for detecting a crack in a welded portion welded along a moving portion that moves along a direction in which the welded portion extends, and is mounted on the moving portion, and together with the moving portion, A temperature distribution acquisition unit that sequentially acquires the temperature distribution in the direction intersecting with the extending direction of the welded part while detecting the infrared radiation energy generated from the object while moving along the extending direction ; Based on the acquired temperature distribution, a temperature gradient calculation unit that calculates a temperature gradient in the welded part, and based on the calculated temperature gradient, the welded part Characterized by comprising a detector for detecting a crack in.

According to such a configuration, the temperature distribution acquisition unit mounted on the moving unit moves along the extending direction of the welded part together with the moving unit, and calculates the temperature distribution in the direction intersecting with the extending direction of the welded part. Are sequentially acquired along the moving direction of the temperature distribution acquisition unit. As a result, even if the deck plate is not forcibly heated by an electromagnetic induction coil or the like, the temperature distribution in the direction intersecting the extending direction of the welded portion is obtained at substantially the same temperature condition for the welded portion extending in the longitudinal direction of the rib. Is possible. Then, the temperature gradient calculation unit calculates a temperature gradient in the welded portion from the acquired temperature distribution, and further, the detection unit detects a crack in the welded portion based on the calculated temperature gradient, thereby generating a crack. It is possible to achieve automatic determination. Thereby, it is possible to easily and quickly determine the presence or absence of cracks in the welded portion, as compared with the case where the evaluator visually observes all acquired temperature distributions to determine the presence or absence of cracks.

Further, the temperature distribution acquisition unit simultaneously acquires a temperature distribution in a direction intersecting with the extending direction of the welded part at a plurality of positions separated from each other in the extending direction of the welded part , and the temperature gradient calculating unit Preferably, a plurality of the temperature gradients are calculated from a plurality of temperature distributions, and the detection unit detects cracks in the welded portion based on the calculated temperature gradients.

  According to such a feature, the temperature distribution acquisition unit simultaneously acquires the temperature distribution at a plurality of positions separated from each other in the extending direction of the welded portion, so that it is possible to acquire a plurality of temperature distributions under substantially the same temperature condition. . And it becomes possible to discriminate | determine accurately the presence or absence of a crack by a detection part detecting the crack in a welding part based on the several temperature gradient calculated from these several temperature distribution.

  In addition, the storage device further includes a storage unit that stores a determination reference value based on a ratio between the temperature gradient in the portion where the crack exists and the temperature gradient in the portion where the crack does not exist, and the temperature distribution acquisition unit includes the welding The temperature distribution at two positions separated from each other in the extending direction of the portion is simultaneously acquired, and the detection unit determines that the ratio between the two temperature gradients obtained from the two temperature distributions is the determination. It is preferable to detect a crack in the welded portion by determining whether or not a reference value has been exceeded.

  According to such a feature, the detection unit determines whether or not the ratio between the two temperature gradients obtained from the temperature distribution at two positions apart from each other exceeds the determination reference value. Since the crack in the welded portion is detected, it is possible to detect the crack with high accuracy while suppressing an increase in the number of data in the temperature distribution. Moreover, since two temperature distributions acquired simultaneously by the temperature distribution acquisition unit are used for this crack detection, the number of acquired data can be reduced, and the speed of acquiring the temperature distribution can be improved. .

  It is preferable that the temperature distribution acquisition unit further includes a temperature distribution information storage unit that stores information regarding the temperature distribution in the welded portion.

  According to this configuration, by using the information on the temperature distribution stored in the temperature distribution information storage unit, the temperature gradient calculation unit calculates the temperature gradient in the welded portion, and the detection unit further calculates the calculated temperature. It is possible to detect cracks in the welded part based on the gradient. Thereby, it is possible to achieve automatic determination of a crack at a position away from the welded portion.

  As described above, according to the method and apparatus for detecting cracks in a steel deck according to the present invention, the presence or absence of cracks in a welded portion of a steel deck can be determined easily and quickly.

It is a cross-sectional view of a bridge provided with a steel slab in which cracks are detected by the method for detecting cracks in a steel slab of the present invention, and shows a state in which an infrared camera is installed on a work vehicle that is a moving part of a crack detection device. FIG. It is an expansion perspective view of the range of the vicinity of the welding part of the deck plate and vertical rib of the steel deck of FIG. It is a cross-sectional view of the vertical rib of FIG. It is an expanded sectional view of the welding part of FIG. It is a block diagram which shows the system configuration | structure of the crack detection apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows a mode that the linear temperature distribution orthogonal to a welding part is acquired with the infrared camera of FIG. It is explanatory drawing which shows the position which acquires the infrared image image | photographed with the infrared camera of FIG. 5, and two linear temperature distributions. It is a graph which shows the data of the linear temperature distribution in the healthy part and crack part which were acquired from the infrared camera of FIG. FIG. 8A is a simplified temperature distribution graph representing the graph of FIG. 8, and FIG. 8B is a temperature change amount with respect to a length change amount in the length direction of the linear portion in the temperature distribution of FIG. It is the graph which expressed simply the change of the differential value regarding. It is a flowchart which shows the procedure of the crack detection method using the crack detection apparatus which concerns on embodiment of this invention. It is a flowchart which shows the procedure for performing the visual determination by the evaluator when a crack is detected by the crack detection apparatus in FIG. It is a modification of the crack detection apparatus of this invention, Comprising: It is a figure which shows the example by which the infrared camera which image | photographs the welding part of the both sides of a vertical rib is arrange | positioned. FIG. 5 is a view showing another modification of the crack detection device of the present invention, which is an example including a pedestal installed movably on an existing rail below the deck plate and an infrared camera mounted on the pedestal. . It is still another modification of the crack detection device of the present invention, and includes a carriage that is movably installed on a bridge along an existing management road, and a measurement device that is mounted on the carriage and includes an infrared camera. It is a figure which shows an example.

Hereinafter, embodiments of a crack detection method and a crack detection apparatus for a steel deck according to the present invention will be described in more detail with reference to the drawings.
(Bridge structure)
First, a general structure of a bridge having a steel deck to which the crack detection method of the present invention is applied will be described.

  FIG. 1 shows a bridge 100 on which the vehicle C can travel. The bridge 100 includes a main girder 101 standing on the ground, a steel deck 102 installed on the main girder 101, and a pavement material 103 made of asphalt or the like laid on the upper surface of the steel deck 102. ing.

  The steel floor slab 102 constitutes a floor plate portion of the bridge 100, and as shown in FIGS. 2 to 4, a flat deck plate 104 and vertical ribs 105 and horizontal ribs 106 that reinforce the deck plate 104. And.

  The vertical ribs 105 are disposed on the lower surface of the deck plate 104, are disposed so as to extend in the traveling direction of the vehicle C (X direction in FIG. 2), and are parallel to the width direction (Y direction in FIG. 2) of the deck plate 104. A plurality are provided side by side.

  Each of the vertical ribs 105 is a so-called U-rib, that is, a rib having a U-shaped cross-section opened upward. As shown in FIG. 3, a pair of vertical ribs 105 are spaced apart from each other and extend downward from the deck plate 104. It has the vertical board 107 and the horizontal board 108 which connects the lower end part 107b of the pair of vertical boards 107 concerned. The vertical ribs 105 correspond to the ribs in the present invention, but in the present invention, the cross-sectional shape of the ribs is not particularly limited, and is not limited to those forming a closed cross section.

  The upper ends 107a of the pair of vertical plates 107 are welded to the deck plate 104 along the longitudinal direction of the vertical rib 105 (see the X direction in FIG. 2) on the surface facing the outside. That is, a weld bead 110 extending along the traveling direction of the vehicle C (the X direction in FIG. 2) is formed at a joint portion between the upper end 107a of the vertical plate 107 and the lower surface of the deck plate 104 in the vertical rib 105. . In a state where the pair of vertical plates 107 of the vertical ribs 105 are welded to the deck plate 104, a closed space 109 (see FIG. 3) is formed by the pair of vertical plates 107, the horizontal plate 108, and the deck plate 104. .

  The lateral ribs 106 are provided along the width direction (Y direction in FIG. 2) so as to be orthogonal to the longitudinal ribs 105. The upper end portion of the horizontal rib 106 is welded to the lower surface of the deck plate 104 along the longitudinal direction of the horizontal rib 106.

(Crack detection device)
The crack detection apparatus 1 according to the present embodiment has a crack 111 (see FIG. 4) in a welded portion of the above-described steel deck 102, that is, a weld bead 110 that is a welded portion that joins the longitudinal rib 105 and the deck plate 104. It is a device that automatically detects.

  Specifically, as shown in FIG. 5, the crack detection device 1 includes the measurement device 2 and the direction in which the measurement device 2 is mounted and the weld bead 110 extends (that is, the X direction in FIG. 2). And a work vehicle 3 moving in the traveling direction). The work vehicle 3 has a drive unit (not shown) and moves in a state of being suspended from a plurality of rails 102 a extending in a traveling direction (a direction perpendicular to the paper in FIG. 1) installed at the lower part of the steel deck 102. It is possible.

  The measuring device 2 includes a temperature distribution acquisition unit 4, a temperature gradient calculation unit 5, a ratio calculation unit 6, a crack detection unit 7, and a determination reference value storage unit 8.

  The temperature distribution acquisition unit 4 performs the temperature distribution in the direction intersecting with the weld bead 110 while moving along with the work vehicle 3 along the direction in which the weld bead 110 extends, for example, in the technique of infrared thermography or infrared camera. Is obtained sequentially along the moving direction of the temperature distribution acquisition unit 4 by detecting infrared radiant energy generated from the object to be detected, and specifically, a linear portion that crosses the welding bead 110 orthogonally By detecting the infrared radiation energy generated from the object from the temperature distributions T1 and T2 (see FIG. 8) of R1 and R2 (see FIGS. 5 and 7), the moving direction of the temperature distribution acquisition unit 4 (that is, the welding bead 110) Sequentially along the direction of extension). The temperature distribution acquisition unit 4 includes an infrared camera 11 and a temperature distribution generation unit 12.

  As shown in FIGS. 5 to 6, the infrared camera 11 is recorded data for acquiring a temperature distribution when the measuring device 2 is moving along with the work vehicle 3 along the extending direction of the weld bead 110. For example, image data, specifically, infrared images of the weld bead 110 and its peripheral part are taken continuously. The continuously captured infrared image (see FIG. 7) is an image in which the temperature distribution is represented by shading, and is information regarding the temperature distribution. The infrared image is stored in an image storage unit 11 a built in the infrared camera 11.

  Moreover, the infrared camera 11 acquires a visible image simultaneously with an infrared image, and memorize | stores it in the image memory | storage part 11a.

  The temperature distribution generation unit 12 is configured to detect the temperature distribution of the two linear portions R <b> 1 and R <b> 2 at two positions separated from each other in the extending direction of the weld bead 110 from the infrared images continuously captured by the infrared camera 11. T1 and T2 (see FIG. 8) are generated simultaneously. The two linear portions R <b> 1 and R <b> 2 are set so as to extend in the direction S orthogonal to the weld bead 110 and cross the weld bead 110.

  Here, as shown in FIG. 7, when the crack 111 occurs along the extending direction of the weld bead 110, the linear portion R1 is a portion that does not cross the crack 111, a so-called healthy portion, The linear portion R2 is a portion that crosses the crack 111, that is, a crack portion. When the deck plate 104 is heated by irradiation with sunlight A in the daytime or the like, the heat of the deck plate 104 is conducted to the vertical rib 105 through the weld bead 110.

  In that case, as shown in FIG. 8, the temperature distribution T1 in the linear portion R1 which is a healthy portion is gradually increased from the end R1a on the deck plate 104 side to the end R1b on the vertical plate 107 side of the vertical rib 105. It can be seen that the temperature distribution gradually decreases.

  On the other hand, the temperature distribution T2 of the linear portion R2 that is the crack portion is such that the crack 111 is in the middle of going from the end portion R2a of the linear portion R2 on the deck plate 104 side to the end portion R2b of the vertical rib 105 on the vertical plate 107 side. Since heat conduction from the deck plate 104 to the vertical rib 105 is interrupted in the portion, it can be seen that the temperature has a temperature distribution in which the temperature drops partially and rapidly.

  The temperature gradient calculation unit 5 calculates the temperature gradient in the weld bead 110 from the temperature distributions T1 and T2 acquired by the temperature distribution acquisition unit 4 as described above.

  Here, as the temperature gradient, for example, the difference between the highest temperature and the lowest temperature in the temperature distribution is preferably used at least at some positions in the extending direction of the weld bead 110. In this case, the temperature gradient is calculated as follows. As shown in the graph of FIG. 9A, the two temperature distributions T1 and T2 acquired by the temperature distribution acquisition unit 4 indicate the lengths of the linear portions R1 and R2 in the length direction in the pixels of the infrared image. This is shown by a curve showing the relationship between the number X of (pixels) and the temperature T at a position corresponding to the number of pixels X. In FIG. 9A, the difference between the highest temperature and the lowest temperature in the temperature distributions T1 and T2 of the linear portions R1 and R2 is obtained as temperature gradients α1 and α2, respectively. As described above, the temperature gradient calculation unit 5 can calculate the temperature gradients α1 and α2 from the difference between the highest temperature and the lowest temperature in the temperature distributions T1 and T2.

  In order to calculate the temperature gradient more accurately, as the temperature gradient, the amount of change in temperature with respect to the amount of change in length in the direction intersecting the weld bead 110 is at least at some positions in the direction in which the weld bead 110 extends. It is preferred that a differential value for is used. In this case, the temperature gradient is calculated as follows. The temperature gradient calculation unit 5 obtains the change amount of the temperature T with respect to the change amount of the pixel number X by differential processing based on the data relating the number of pixels X and the temperature T shown in the graph of FIG. 9A. , The change of the differential value dT / dx with respect to the number of pixels X is obtained. The differential values dT / dx at the positions corresponding to the number of pixels X in the temperature distributions T1 and T2 are respectively shown as curves U1 and U2 by the graph of FIG. 9B.

  In the graph of FIG. 9B, the curve U1 indicating the differential value dT / dx corresponding to the temperature distribution T1 of the linear portion R1 that does not cross the crack 111 has a minimum value of the differential value dT / dx (that is, a downward slope). Is the maximum value of β1. On the other hand, in the curve U2 indicating the differential value dT / dx corresponding to the temperature distribution T2 of the linear portion R2 crossing the crack 111, the minimum value of the differential value dT / dx is indicated by β2. The temperature gradient calculation unit 5 can calculate the minimum values β1 and β2 of these differential values dT / dx as temperature gradients.

  The ratio calculation unit 6 includes two temperature gradients calculated by the temperature gradient calculation unit 5, that is, between two temperature gradients obtained from the temperature distributions T1 and T2 of the two linear portions R1 and R2. Find the ratio. For example, the ratio calculation unit 6 calculates the ratio β2 / β1 between the minimum values β1 and β2 of the differential value dT / dx calculated by the temperature gradient calculation unit 5 as the temperature gradient.

  The determination reference value storage unit 8 stores a determination reference value based on a ratio between a temperature gradient in a portion of the weld bead 110 where the crack 111 exists and a temperature gradient in a portion where the crack 111 does not exist. The determination reference value C1 is, for example, the average value of the temperature gradient in the portion where the crack 111 exists (for example, the minimum of the differential value dT / dx) from the data group of the temperature distribution of the linear portion in the weld bead 110 acquired in the past. Average value β20) and an average value of the temperature gradient in the portion where the crack 111 does not exist (for example, average value β10 of the minimum value of the differential value dT / dx), respectively, and the ratio of these temperature gradients (β20 / β10) Is set based on Note that the determination reference value C1 is set in consideration of various conditions at the time of measuring the temperature distribution (for example, noise at the time of photographing with the infrared camera 11 and a paint state on the weld bead 110).

  The crack detection unit 7 detects the crack 111 in the weld bead 110 based on a plurality of temperature gradients (for example, the differential values β1 and β2 described above) calculated by the temperature gradient calculation unit 5. Specifically, the crack detection unit 7 determines that the ratio β2 / β1 between the two temperature gradients β1 and β2 obtained from the temperature distributions T1 and T2 of the two linear portions R1 and R2 is the above criterion. By determining whether or not the value C1 is exceeded, the crack 111 in the weld bead 110 is detected.

(Explanation of crack detection method)
The presence or absence of the crack 111 in the weld bead 110 which joins the deck plate 104 and the vertical rib 105 of the steel deck 102 is detected by the following procedures using the crack detection apparatus 1 configured as described above.

  In this temperature detection method, as an example of the temperature gradient, as described above, the differential values in the curves U1 and U2 indicating the differential values dT / dx corresponding to the temperature distributions T1 and T2 of the linear portions R1 and R2, respectively. The minimum values β1 and β2 of dT / dx are used.

  First, before the work vehicle 3 is started, the temperature gradient in the portion of the weld bead 110 where the crack 111 exists and the temperature gradient in the portion where the crack 111 does not exist are stored in the determination reference value storage unit 8 in advance as described above. The determination reference value C1 based on the ratio is stored (determination reference value preparation step). Specifically, as described above, the determination reference value C1 is an average value of the temperature gradient in the portion where the crack 111 exists (for example, from the temperature distribution data group of the linear portion in the weld bead 110 acquired in the past (for example, , The average value β20 of the minimum value of the differential value dT / dx) and the average value of the temperature gradient in the portion where the crack 111 does not exist (for example, the average value β10 of the minimum value of the differential value dT / dx), respectively. , Based on the ratio of these temperature gradients (β20 / β10). At this time, the determination reference value C1 is not limited to the various conditions at the time of measuring the temperature distribution, for example, noise at the time of photographing with the infrared camera 11 and the coating state on the weld bead 110, as well as the weather on the day of measurement (temperature, solar radiation). It is set by correcting it appropriately in consideration of conditions such as (state).

  With the determination reference value C1 stored in the determination reference value storage unit 8 as described above, first, a temperature acquisition process is performed. The temperature acquisition process is performed in the daytime when sunlight A (see FIG. 2) irradiates the pavement material 103 to heat the pavement material 103 and the deck plate 104 is heated by the heat of the pavement material 103. . In the temperature acquisition step, as shown in step S1 of the flowchart of FIG. 10, the work vehicle 3 is started and moved in the extending direction of the weld bead 110 of the vertical rib 105, and the measuring device mounted on the work vehicle 3. Two infrared cameras 11 continuously take infrared images of the weld bead 110 and its peripheral part. At the same time, the infrared camera 11 simultaneously captures a visible image of that portion. The continuously captured infrared image (see FIG. 7) and the visible image are stored in the image storage unit 11 a built in the infrared camera 11.

  Next, as shown in step S <b> 2, the temperature distribution generation unit 12 has two temperature distribution generators 12 at two positions away from each other in the extending direction of the weld bead 110 from the infrared images continuously captured by the infrared camera 11. The temperature distributions T1 and T2 of the linear portions R1 and R2 are generated. As a result, the temperature distribution acquisition unit 4 acquires two temperature distributions T1 and T2.

  At this time, the temperature distribution generation unit 12 removes noise included in the respective temperature distributions T1 and T2 by a spatial averaging method or the like.

  Thereafter, as shown in step S3, the temperature gradient calculation unit 5 calculates the temperature gradients of the two acquired temperature distributions T1 and T2. Specifically, the temperature gradient calculation unit 5 uses the data of the pixel number X and the temperature T in each temperature distribution T1, T2 shown in the graph of FIG. The amount of change in the temperature T is obtained by differential processing, thereby generating data of the differential value dT / dx with respect to the number of pixels X indicated by the curves U1 and U2 in the graph of FIG. 9B. And the temperature gradient calculation part 5 calculates minimum value (beta) 1, (beta) 2 of the differential value dT / dx in these curves U1, U2 as a temperature gradient.

  Next, as shown in step S4, the ratio calculation unit 6 uses the minimum values β1, β2 of the differential values dT / dx as the ratio between the two temperature gradients calculated by the temperature gradient calculation unit 5. The ratio β2 / β1 between is calculated.

  Thereafter, in step S5, the crack detection unit 7 determines that the ratio β2 / β1 between the two temperature gradients β1 and β2 obtained from the temperature distributions T1 and T2 of the two linear portions R1 and R2 is a criterion value. It is determined whether or not C1 is exceeded.

  If the ratio β2 / β1 is larger than the determination reference value C1, the crack detection unit 7 automatically determines that there is a crack as in step S6. On the other hand, if the ratio β2 / β1 is not greater than the determination reference value C1, the crack detection unit 7 automatically determines that there is no crack as in step S7. Thereby, it is possible to automatically detect the crack 111 in the weld bead 110.

  Note that even if the crack detection unit 7 automatically determines that there is a crack 111 in the weld bead 110, the actual condition depends on various measurement conditions (for example, the resolution of the infrared camera and the coating unevenness in the weld bead 110). In some cases, even if the crack 111 does not exist, it is erroneously automatically determined that the crack 111 exists.

  Therefore, in order to improve the determination accuracy of the crack 111, it is preferable to perform a comprehensive final determination by the evaluator after the automatic determination by the crack detection device 1 is completed.

  When performing a comprehensive final determination by the evaluator, for example, in step S6 of FIG. 10, after the crack detection unit 7 automatically determines that there is a crack 111 in the weld bead 110, the evaluation is performed according to the flowchart of FIG. Image processing is performed so that a person can easily visually observe.

  First, as shown in step S11, among the infrared image data stored in the image storage unit 11a of the infrared camera 11, image data of a portion automatically determined as having a crack by the crack detection unit 7 is detected as a crack. Image processing is performed by an image processing apparatus (not shown) built in the apparatus 1. In the image processing, for example, infrared image data is numerically analyzed to correct the image to such an extent that the tip of the crack can be specified, thereby processing the material so that it is easy for the evaluator to visually observe.

  Thereafter, as shown in step S12, the evaluator not only displays the infrared image after the image processing displayed on the monitor (not shown) but also the acquired visible image, the infrared image before the image processing, the temperature distribution T1, A comprehensive determination is made using infrared processing data such as T2 and various other data. As a result, the evaluator comprehensively makes a final determination as to whether or not there is a crack in the portion automatically determined as having a crack by the crack detection unit 7 (steps S13 and S14).

  Note that the image processing apparatus and the monitor described above are attached to the crack detection apparatus 1, for example, but may be installed outside the crack detection apparatus 1.

  As described above, after the crack is automatically determined by the crack detection apparatus 1, the evaluator performs visual determination using the infrared image after image processing, whereby the accuracy of crack determination is improved.

(Feature)
(1)
In the crack detection method of the above embodiment, the temperature acquisition unit 4 that acquires the temperature distribution by detecting the infrared radiation energy generated from the object is moved along the direction in which the weld bead 110 extends, and orthogonal to the weld bead 110. By sequentially acquiring the temperature distributions T1 and T2 of the linear portions R1 and R2 with respect to the direction along the moving direction of the temperature acquisition unit 4 by detecting the infrared radiation energy generated from the object, the deck plate is electromagnetically induced. Even if it is not forcibly heated by a coil or the like, it is possible to acquire the temperature distribution in the direction intersecting the weld bead 110 extending in the longitudinal direction of the vertical rib 105 under substantially the same temperature condition.

  Then, it is possible to calculate a temperature gradient in the weld bead 110 from the acquired temperature distribution and automatically detect the crack 111 in the weld bead 110 based on the calculated temperature gradient. Accordingly, it is possible to easily and quickly determine the presence or absence of the crack 111 in the weld bead 110, as compared with the case where the evaluator visually observes all the acquired temperature distributions to determine the presence or absence of the crack 111. It is.

(2)
In the crack detection method of the above embodiment, the temperature distribution acquisition step (particularly the step of taking an infrared image with the infrared camera 11) is performed during the daytime such as the daytime when the deck plate 104 is heated by the irradiation of sunlight A. Therefore, the temperature of the deck plate 104 heated by the irradiation of sunlight increases. Therefore, the temperature distribution in the weld bead 110 becomes clearer than the difference in temperature gradient between the case where the crack 111 is present and the case where the crack 111 is not present, so that the presence or absence of the crack 111 can be accurately determined.

(3)
In the crack detection method of the above-described embodiment, the temperature distributions T1 and T2 are simultaneously acquired at a plurality of positions (for example, two positions) separated from each other in the extending direction of the weld bead 110. Therefore, the plurality of temperature distributions T1 and T2 are acquired. Can be obtained under substantially the same temperature conditions. Then, by detecting the crack 111 in the weld bead 110 based on a plurality of temperature gradients calculated from the plurality of temperature distributions, it is possible to accurately determine the presence or absence of the crack 111. In addition, the position which acquires temperature distribution may be two or more places.

(4)
Moreover, in the crack detection method of the said embodiment, before a temperature distribution acquisition process, a criterion value is prepared beforehand by the ratio of the temperature gradient in the part in which the crack 111 exists, and the temperature gradient in the part in which the crack 111 does not exist. The method further includes a determination reference value preparation step. In the temperature distribution acquisition step, temperature distributions at two positions separated from each other in the extending direction of the weld bead 110 are simultaneously acquired, and in the detection step, the temperature distribution is obtained from the two temperature distributions. The crack 111 in the weld bead 110 is detected by determining whether or not the ratio between the two temperature gradients exceeds the determination reference value. In such a feature, the weld bead 110 is determined by determining whether or not the ratio between two temperature gradients obtained from the temperature distribution at two positions apart from each other exceeds a preset criterion value. Therefore, it is possible to detect the crack 111 with high accuracy while suppressing an increase in the number of data in the temperature distribution. In addition, since two temperature distributions acquired at the same time are used for this crack detection, the number of data to be acquired can be reduced, and the speed of acquiring the temperature distribution can be improved.

(5)
In the crack detection method of the above-described embodiment, it is preferable that the difference α1, α2 between the highest temperature and the lowest temperature in the temperature distribution is used as the temperature gradient at least at some positions in the extending direction of the weld bead 110. . Thus, since the temperature gradient can be easily calculated from the differences α1 and α2 between the maximum temperature and the minimum temperature, it is possible to suppress an increase in the burden of calculation processing.

(6)
Further, in the crack detection method of the above embodiment, as the temperature gradient, at least at some positions in the direction in which the weld bead 110 extends, the differential with respect to the change in temperature with respect to the change in length in the direction intersecting the weld bead 110. It is preferable to use values (for example, minimum values β1 and β2 of differential values). According to this feature, since the temperature gradient is calculated based on the differential values β1 and β2 of the temperature change with respect to the change in length in the direction intersecting the weld bead 110, the temperature gradient can be calculated more accurately. As a result, it is possible to accurately detect the crack 111 based on an accurate temperature gradient.

(7)
In the crack detection method of the above embodiment, the ribs welded to the deck plate 104 connect the pair of vertical plates 107 that are spaced apart from each other and extend downward from the deck plate 104 and the lower ends of the pair of vertical plates 107. And a pair of vertical plates 105 are welded along the longitudinal direction of the vertical ribs 105 to the deck plate 104. A closed space 109 may be formed by 107, the lateral plate 108, and the deck plate 104. In this case, since welding cannot be performed from the inside of the vertical rib 105, the upper ends of the pair of vertical plates 107 of the vertical rib 105 are welded to the deck plate 104 only from the outside, and the deck plate 104 and the vertical rib 105 are The weld bead 110 joining the two is very weak, and the weld bead 110 is likely to be cracked 111. Therefore, by executing the crack detection method described above, it is possible to easily and quickly detect the crack 111 in the weld bead 110 of such a longitudinal rib 105. As a result, inspection of the weld bead 110 of the vertical rib 105, which is likely to crack, can be performed in many places in a short period of time.

(8)
Moreover, in the crack detection apparatus 1 of the steel floor slab 102 of the said embodiment, while the temperature distribution acquisition part 4 moves along the direction where the weld bead 110 extends with the movement of the work vehicle 3 which is a moving part, the said weld bead is concerned. The temperature distribution in the direction intersecting 110 is sequentially acquired along the moving direction of the temperature distribution acquisition unit 4 by detecting the infrared radiation energy generated from the object. As a result, even if the deck plate is not forcibly heated by an electromagnetic induction coil or the like, the temperature distribution of the weld bead 110 extending in the longitudinal direction of the longitudinal rib 105 in the direction intersecting with the weld bead 110 under substantially the same temperature condition. It is possible to obtain. Then, the temperature gradient calculation unit 5 calculates the temperature gradient in the weld bead 110 from the acquired temperature distribution, and the crack detection unit 7 further detects the crack 111 in the weld bead 110 based on the calculated temperature gradient. By detecting, automatic determination of the crack 111 can be achieved. Accordingly, it is possible to easily and quickly determine the presence or absence of the crack 111 in the weld bead 110, as compared with the case where the evaluator visually observes all the acquired temperature distributions to determine the presence or absence of the crack 111. It is.

(9)
Moreover, in the crack detection apparatus 1 of the said embodiment, since the temperature distribution acquisition part 4 acquires temperature distribution simultaneously in the several position distant from each other in the extending direction of the weld bead 110, a plurality of temperature distribution is made into the substantially same temperature conditions. It is possible to get at. Then, the crack detection unit 7 can accurately determine the presence or absence of the crack 111 by detecting the crack 111 in the weld bead 110 based on the plurality of temperature gradients calculated from the plurality of temperature distributions. .

(10)
In the crack detection device 1 of the above embodiment, the crack detection unit 7 determines that the ratio between the two temperature gradients obtained from the temperature distributions T1 and T2 at two positions separated from each other is the determination reference value. Since the crack 111 in the weld bead 110 is detected by discriminating whether or not the value has exceeded, it is possible to detect the crack 111 with high accuracy while suppressing an increase in the number of data in the temperature distribution. Moreover, since two temperature distributions acquired simultaneously by the temperature distribution acquisition unit 4 are used for this crack detection, the number of data to be acquired can be reduced, and the speed of acquiring the temperature distribution can be improved. is there.

(11)
Moreover, in the crack detection apparatus 1 of the said embodiment, the temperature gradient calculation part 5 calculates the temperature gradient in the weld bead 110 by using the infrared image memorize | stored in the image storage part 11a, and also the crack detection part 7 However, it is possible to detect the crack 111 in the weld bead 110 based on the calculated temperature gradient. Thereby, it is possible to achieve automatic determination of the crack 111 at a position away from the weld bead 110.

(Modification)
(A)
In the crack detection method and the crack detection apparatus of the above embodiment, as an example of the temperature distribution in the direction intersecting the weld bead 110, the temperature distributions T1 and T2 in the direction orthogonal to the weld bead 110 are exemplified. However, the present invention is not limited to this. For example, as long as the direction intersects the weld bead 110, the temperature distribution in the direction intersecting the weld bead 110 at an angle of 1 to 89 degrees with respect to the direction in which the weld bead 110 extends may be adopted. Good.

(B)
In the crack detection method of the above-described embodiment, the infrared camera 11 of the temperature distribution acquisition unit 4 continuously captures infrared images of the weld bead 110 and its peripheral part while moving. It is not limited to. In this invention, the temperature distribution acquisition part 4 should just acquire the temperature distribution about the direction which cross | intersects the weld bead 110 along the moving direction sequentially, for example, in the moving direction of the infrared camera 11 of the temperature distribution acquisition part 4. The infrared images may be sequentially acquired intermittently in the manner of time-lapse photography.

(C)
In the temperature detection method of the above embodiment, as a plurality of temperature gradients, two differential values relating to the amount of change in temperature with respect to the amount of change in length in the direction intersecting the weld bead 110 as a value at which the temperature gradient can be calculated most accurately. (Specifically, the minimum values β1 and β2 of differential values) are used, and the ratio β2 / β1 is a comparison target with the determination reference value at the time of crack determination, but the present invention is limited to this. It is not a thing.

  As another example of the plurality of temperature gradients, it is possible to use the difference α1, α2 between the highest temperature and the lowest temperature in the temperature distribution, and compare the ratio α2 / α1 with the corresponding criterion value to determine the crack. May be performed. In this case, it is possible to reduce the burden of calculation processing compared to the case where the above-described differential value is used.

  As still another example of the plurality of temperature gradients, the difference α1 between the maximum temperature and the minimum temperature is used as a temperature gradient at one position in the extending direction of the weld bead 110, and the temperature gradient at another position is welded. A differential value related to the amount of change in temperature with respect to the amount of change in length in the direction intersecting the bead 110 (for example, the minimum value β2 of the differential value) may be used. In that case, the crack determination may be performed by comparing the ratio β2 / α1 with the corresponding determination reference value. In this case, it is possible to achieve both the accurate calculation of the temperature gradient and the suppression of the calculation processing burden. In addition, when performing crack determination using this ratio β2 / α1, the determination may be made based on whether or not the absolute value of the ratio β2 / α1 exceeds the corresponding determination reference value.

(D)
In the crack detection device 1 of the above embodiment, the image storage unit 11a is exemplified as an example of the temperature distribution information storage unit, but the present invention is not limited to this. For example, the crack detection apparatus 1 may include a storage unit that stores data of the temperature distributions T1 and T2 generated using infrared images as the temperature distribution information storage unit.

(E)
In the crack detection device 1 of the above embodiment, the entire measuring device 2 including the infrared camera 11 is mounted on the work vehicle 3, but the present invention is not limited to this, and the work vehicle 3 includes at least The infrared camera 11 (that is, part of the temperature distribution acquisition unit 4) may be mounted on the work vehicle 3 to acquire an infrared image and store it in the image storage unit 11a.

(F)
As shown in FIG. 1, the crack detection device 1 of the above embodiment shows an example in which one infrared camera 11 is mounted on the work vehicle 3, but the present invention is limited to this. Instead, a plurality of infrared cameras 11 may be mounted on one work vehicle 3 as shown in FIG. In that case, it is possible to simultaneously acquire infrared images of the welded portions (weld beads 110) of the plurality of vertical ribs 105. Thereby, it is possible to simultaneously determine the cracks in the plurality of weld beads 110, and the working efficiency is greatly improved.

(G)
In the crack detection device 1 described above, the working vehicle 3 suspended on the plurality of rails 102a below the steel deck 102 is described as an example of the moving unit that moves along the extending direction of the weld bead 110. However, the present invention is not limited to this, and any other means can be used as the moving portion as long as it can move along the direction in which the weld bead 110 extends.

  For example, as in the crack detection device 21 shown in FIG. 13, the frame 22 is suspended from the rails 102 a below the steel floor slab 102, and the infrared camera 11 is mounted on the frame 22. There may be. In this structure, each gantry 22 is installed movably along the rail 102a with respect to the rail 102a. The gantry 22 has a drive unit (not shown) and may be moved along the rail 102a. Since the infrared camera 11 is mounted on each pedestal 22, the infrared camera 11 sequentially acquires (for example, continuously) infrared images of the welded portion of the vertical rib 105 while moving, and the infrared image is acquired from the infrared camera. 11 can be stored in a built-in image storage unit (not shown). In the crack detection device 21 shown in FIG. 13, the components of the measurement device 2 other than the infrared camera 11 may be separately installed outside the gantry 22.

(H)
As still another example of the moving unit, a configuration that can travel on the management road 121 of the bridge 100 as in the crack detection device 31 shown in FIG.

  The bridge 100 is usually provided with a management path 121 through which an operator can pass for the purpose of maintenance and inspection of the bridge. The management path 121 is installed on the side surface of the main beam 101 below the steel deck 102, for example. The management path 121 extends along the longitudinal direction of the vertical rib 105.

  The crack detection device 31 traveling on such a management road 121 includes a measurement device 32 and a carriage 33 on which the measurement device 32 is mounted. The measuring device 32 has an infrared camera 34. The carriage 33 has a drive unit (not shown), and can travel on the management path 121 along the longitudinal direction of the vertical rib 105. In such a crack detection device 31, while the carriage 33 travels along the management path 121, the infrared camera 11 sequentially acquires (for example, continuously) infrared images of the welded portion of the vertical rib 105, and the vertical rib 105 It is possible to determine the presence or absence of a crack in the welded portion.

(I)
In the above embodiment, the vertical rib 105 is described as an example of the rib welded to the deck plate. However, the present invention is not limited to this, and the rib welded to the deck plate may be used. For example, the crack detection method and the crack detection apparatus of the present invention can determine whether or not there is a crack in the welded portion, and for example, can also determine whether or not there is a crack in the welded portion at the upper end of the lateral rib 106. It is.

DESCRIPTION OF SYMBOLS 1 Crack detection apparatus 2 Measuring apparatus 3 Work vehicle 4 Temperature distribution acquisition part 5 Temperature gradient calculation part 6 Ratio calculation part 7 Crack detection part 8 Judgment reference value memory | storage part 100 Bridge 102 Steel floor slab 104 Deck plate 105 Vertical rib (rib)
107 Vertical plate 108 Horizontal plate 109 Closed space 110 Weld bead 111 Crack

Claims (11)

In a steel deck having a deck plate and a rib arranged on the lower surface of the deck plate, a crack for detecting a crack in a welded portion in which the rib is welded to the deck plate along the longitudinal direction of the rib A detection method,
While detecting an infrared radiant energy generated from the object, a device for obtaining a temperature distribution is moved along the extending direction of the welded part , and the temperature distribution in the direction intersecting the extending direction of the welded part is determined. A temperature distribution acquisition step of sequentially acquiring along the moving direction of the device by detecting infrared radiation energy generated from
From the acquired temperature distribution, a temperature gradient calculating step for calculating a temperature gradient in the welded portion;
And a detection step of detecting a crack in the welded portion based on the calculated temperature gradient. The temperature distribution acquisition step is performed when the deck plate is heated by sunlight irradiation.
The crack detection method of the steel deck according to claim 1. In the temperature distribution acquisition step, the temperature distribution in the direction intersecting the extending direction of the welded part at a plurality of positions separated from each other in the extending direction of the welded part is simultaneously acquired,
In the temperature gradient calculation step, a plurality of the temperature gradients are calculated from the plurality of temperature distributions,
In the detection step, based on the calculated temperature gradients, a crack in the welded portion is detected.
The crack detection method of the steel deck according to claim 1 or 2. Prior to the temperature distribution acquisition step, further includes a determination reference value preparation step of preparing a determination reference value in advance by a ratio of the temperature gradient in the portion where the crack exists and the temperature gradient in the portion where the crack does not exist. ,
In the temperature distribution acquisition step, temperature distributions at two positions separated from each other in the extending direction of the welded portion are simultaneously acquired,
In the detection step, a crack in the welded portion is detected by determining whether a ratio between the two temperature gradients obtained from the two temperature distributions exceeds the determination reference value. ,
The crack detection method of the steel deck according to claim 3. As the temperature gradient, a difference between the highest temperature and the lowest temperature in the temperature distribution is used in at least a part of the position in the extending direction of the welded portion.
The crack detection method of the steel deck according to any one of claims 1 to 4. As the temperature gradient, a differential value relating to the amount of change in temperature with respect to the amount of change in length in the direction intersecting the extending direction of the welded part is used in at least a portion of the position in the extending direction of the welded part.
The crack detection method of the steel deck according to any one of claims 1 to 5. The rib has a pair of vertical plates that are spaced apart from each other and extend downward from the deck plate, and a horizontal plate that connects the lower ends of the pair of vertical plates,
The upper ends of the pair of vertical plates are welded to the deck plate along the longitudinal direction of the ribs, so that a closed space is formed by the pair of vertical plates, the horizontal plate, and the deck plate. The
The crack detection method of the steel deck according to any one of claims 1 to 6. In a steel deck having a deck plate and a rib arranged on the lower surface of the deck plate, a crack for detecting a crack in a welded portion in which the rib is welded to the deck plate along the longitudinal direction of the rib A detection device,
A moving part that moves along a direction in which the welded portion extends,
The infrared radiation energy generated from the object is detected in the temperature distribution in the direction intersecting with the extending direction of the welding part while being mounted on the moving part and moving along the extending direction of the welding part together with the moving part. The temperature distribution acquisition unit that sequentially acquires along the moving direction by,
From the acquired temperature distribution, a temperature gradient calculation unit that calculates a temperature gradient in the welded portion, and
A steel floor slab crack detection apparatus comprising: a detection unit configured to detect a crack in the welded portion based on the calculated temperature gradient. The temperature distribution acquisition unit simultaneously acquires a temperature distribution in a direction intersecting with the extending direction of the welded part at a plurality of positions separated from each other in the extending direction of the welded part,
The temperature gradient calculation unit calculates a plurality of the temperature gradients from the plurality of temperature distributions,
The detection unit detects cracks in the welded portion based on the calculated temperature gradients.
The crack detection apparatus of the steel deck according to claim 8. A determination reference value storage unit that stores a determination reference value based on a ratio between the temperature gradient in the portion where the crack exists and the temperature gradient in the portion where the crack does not exist;
The temperature distribution acquisition unit simultaneously acquires temperature distributions at two positions separated from each other in the extending direction of the welded portion,
The detection unit detects a crack in the welded portion by determining whether a ratio between the two temperature gradients obtained from the two temperature distributions exceeds the determination reference value. ,
The crack detection apparatus of the steel deck according to claim 9. The temperature distribution acquisition unit further includes a temperature distribution information storage unit that stores information on the temperature distribution in the welded part.
The crack detection apparatus of the steel deck according to any one of claims 8 to 10.