JP2013024008A - Transverse rib structure for fatigue improvement, and steel floor slab using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for fatigue resistance improvement at a weld zone between a transverse rib constituting a steel floor slab or the like and a plate-like member formed of a deck plate, which allows a generated stress acting on both of a toe part and a root part to be reduced.SOLUTION: A structure for fatigue resistance improvement is used for a steel floor slab having a plurality of transverse ribs 3, open sectional ribs (longitudinal ribs) 4 with a plurality of open cross sections which are crossed with the transverse ribs 3 and supported thereby, and a deck plate 5 which is welded and fixed to the upper side of the transverse ribs 3 and the open sectional ribs (longitudinal ribs ) 4. The transverse ribs 3 are provided with a web 3A extending in vertical direction. The web 3A is provided with a plurality of cutout concavities 3C extending downward with an upper opening. One side end face of the cutout concavity 3C is provided with a semicircular cutout part 31. The upper edge of the cutout concavity 3C is provided with a groove part 32 above the semicircular cutout part 31.

Description

  The present invention relates to a structure for improving fatigue of a lateral rib used in a welded structure such as a bridge, and a steel deck using the same.

Conventionally, as a structure of steel floor slabs used for road bridges, etc., a notch is provided in a horizontal rib (horizontal girder), and a vertical rib is inserted into this notch to cross the horizontal rib and the vertical rib. In FIG. 1, the horizontal rib and the vertical rib are welded together along the notch, and the deck plate is welded and fixed to the upper side of the horizontal rib and the vertical rib (for example, see Patent Document 1).
The vertical ribs used in such steel slabs have closed cross-section ribs such as U-shaped U-ribs, flat plate ribs extending vertically, and enlarged portions at the lower plate ends extending vertically. An open cross-section rib such as a valve plate rib (valve rib) having a cross-sectional shape is known. And the notch shape and welding position of a horizontal rib are prescribed | regulated according to the cross-sectional shape of these vertical ribs.

  That is, when the vertical rib is a U-rib, a pair of side end edges along the left and right side surfaces of the U-rib and a lower end edge along the lower surface of the U-rib have a notch shape that is continuous with scallops. The pair of side edge portions and the left and right side surfaces of the U rib are joined by single-sided fillet welding. On the other hand, in the case of flat ribs and valve ribs, a notch shape that extends vertically and has a scallop at the lower end and has a longitudinal groove shape, and has a width dimension through which the flat plate portion of the flat plate rib and the enlarged portion of the valve rib can be inserted Thus, one side edge portion of the notch and the flat plate side surface of the flat plate rib or valve rib are joined by single-sided fillet welding.

JP 2008-280753 A

However, the conventional steel slab with open cross-section ribs has the following problems.
That is, the repeated stress action is caused by the position of the wheel of the vehicle traveling on the deck plate, that is, the position of the dynamic load acting on the deck plate. Therefore, there is a high possibility that fatigue cracks are generated from the root portion of the welded portion between the deck plate and the lateral rib and the welded portion at the position where the longitudinal rib and the lateral rib intersect.
As a method of reducing the generated stress at the joint between the horizontal rib and the vertical rib, the interval between the horizontal ribs is reduced. The normal steel slab is allowed to increase the distance between the horizontal ribs to 2.5 m, but even if the generated stress is reduced by reducing the distance to the 1.25 m distance, a sufficient fatigue prevention effect can be obtained. Not. Furthermore, as this interval is narrowed, the number of welded joints increases, and the manufacturing cost increases. However, in this case, the stress at the welded portion between the deck plate and the lateral rib cannot be reduced.

By the way, a semi-circular notch method is known as a method for improving the fatigue performance of the vertical ribs of the main girder of a bridge having a steel deck. This semi-circular notch is provided at the upper end of the vertical rib and can prevent fatigue cracks from the toe on the deck plate side, but fatigue cracks from the root There was a problem that it was not effective.
In addition, only the compressive and bending stresses are applied to the vertical ribs, whereas the welds between the transverse ribs and the deck plate act not only in compression but also in tension, so a semicircle is cut at the intersection between the deck plate and the transverse ribs. Even if the chipping method is applied, fatigue crack generation from the root side cannot be prevented, so that a sufficient effect cannot be obtained, and there is room for improvement in that respect.

  The present invention has been made in view of the above-described problems. In a welded portion between a horizontal rib and a plate-like member constituting a steel deck or the like, a generated stress acting on both a toe portion and a root portion is generated. An object of the present invention is to provide a structure for improving fatigue of a lateral rib that can be reduced, and a steel deck using the same.

  In order to achieve the above object, in the structure for improving fatigue of a lateral rib according to the present invention, a plurality of lateral ribs, a plurality of longitudinal ribs having an open cross-section supported so as to intersect with the lateral ribs, the lateral ribs and the longitudinal ribs. It is a structure for improving fatigue of a lateral rib used in a welded structure including a plate-like member welded and fixed on the upper side of the rib, and the lateral rib has at least a web extending in the vertical direction. A plurality of cutout recesses that open upward and extend downward are formed, and a semicircular cutout is formed on one side end surface of the cutout recess, and the cutout recess above the semicircular cutout It is characterized in that a groove portion is provided at the upper edge end of.

  Further, the steel deck using the lateral rib fatigue improving structure according to the present invention is a steel deck using the lateral rib fatigue improving structure described above, and the plurality of horizontal ribs are supported by the main girder. The plate-like member welded and fixed to the upper side of the horizontal rib and the vertical rib is a deck plate.

  Thereby, in the steel deck using the open cross-section rib such as a valve plate or a flat plate as the vertical rib, a horizontal rib shape to which the structure of the present invention is applied is obtained.

In the present invention, by providing a semicircular cutout at the side edge of the cutout recess in the horizontal rib, the compressive stress and bending stress acting on the platelike member can be reduced. It is possible to prevent fatigue cracks that occur from the toe portion. And, by providing a groove at the upper edge of the notch recess, the tensile stress acting on the plate member can be reduced, so that the fatigue crack generated in the root portion on the plate member side of the lateral rib can be reduced. Can be prevented.
As described above, in the structure for improving fatigue of a lateral rib according to the present invention, it is possible to cope with both compressive stress and tensile stress. For example, a deck in which both compression and tension bending occurs depending on the position of a wheel of a traveling vehicle. It is particularly suitable for a steel deck having a welded portion between a plate and a lateral rib.

  In addition, since the fatigue improvement effect described above can be exhibited without increasing the radial dimension of the semicircular notch, there is an advantage that the rigidity and strength required for the lateral rib are not reduced.

  Further, in the structure for improving fatigue of a lateral rib according to the present invention, the groove portion is preferably set to be larger than ½ of the thickness dimension of the lateral rib.

  Further, the steel slab using the lateral rib fatigue improving structure according to the present invention uses the above-described lateral rib fatigue improving structure, and intersects with the lateral ribs supported by the main girder. A plurality of vertical ribs and a deck plate that is welded and fixed to the horizontal ribs and the upper side of the vertical ribs, the horizontal ribs having at least a web extending vertically, The web is formed with a plurality of cutouts that open upward and extend downward, and the vertical ribs are substantially inverted T-shaped or substantially L-shaped from a web that extends vertically and a flange that continues to the lower end of the web. The ribs at the positions corresponding to the notches of the horizontal ribs are cut and formed, and the webs of the horizontal ribs and the vertical ribs are inserted into the notches of the horizontal ribs. Is welded along the notch There are those characterized by.

Further, using the lateral rib fatigue improving structure according to the present invention, having a substantially inverted T-shaped or substantially L-shaped cross section, a flange at a position corresponding to the notch of the lateral rib is formed by notching, In the steel floor slab, characterized in that the webs of the horizontal ribs and the vertical ribs are welded together along the notches with the webs of the vertical ribs inserted through the notches of the horizontal ribs, The interval is preferably set in a range of 3 m or more and 8 m or less.
By setting the distance between the lateral ribs in such a range, the rear wheel load of the vehicle such as a truck can be limited to one vehicle at the main portion of the lateral rib influence line. Fatigue cracks arising from the toe portion on the plate-like member side can be prevented more reliably. In the case of ordinary valve ribs and flat plate ribs, the distance between the lateral ribs is limited to 2.5 m or less.

Further, in the structure for improving fatigue of a lateral rib according to the present invention, the welded structure is an existing structure, and the existing structure may be used for repair in which a semicircular cutout portion and a groove portion are provided.
In this case, a semicircular cutout portion and a groove portion are provided to the existing lateral rib, and at this time, the shape of the groove portion is, for example, a J shape or a half U shape. Even repair welding can be performed. Therefore, a repair structure capable of reducing the generated stress acting on both the toe portion and the root portion can be realized, and fatigue cracks from the toe portion and the root portion can be prevented.

  According to the structure for improving fatigue of a lateral rib of the present invention and a steel deck using the same, in the welded portion between the lateral rib and the plate-like member constituting the steel deck, etc., both at the toe portion and the root portion. The generated stress acting can be reduced, fatigue cracks from the toe portion and the root portion can be prevented, and the fatigue life can be improved.

It is a perspective view which shows the outline | summary of the fatigue improvement structure of the horizontal rib by the 1st Embodiment of this invention, and the steel deck using this. It is the perspective view which expanded a part of fatigue improvement structure shown in FIG. It is a front view which shows the structure of the notch recessed part of a horizontal rib. FIG. 4 is an enlarged view showing a part of the cutout recess in FIG. 3, wherein (a) is a view before fillet welding at the groove portion, and (b) is a view after fillet welding at the groove portion. It is an expansion perspective view which shows the detail of the notch recessed part of a horizontal rib. It is a figure which shows the shape of the notch recessed part of a horizontal rib by a test example, Comprising: (a) is an Example, (b) is the comparative example 1, (c) is the comparative example 2. FIG. It is a figure which shows the result by a test example. It is a perspective view which shows the fatigue improvement structure by 2nd Embodiment, Comprising: It is a figure corresponding to FIG. It is a side view of the notch recessed part of a horizontal rib shown in FIG. 8, Comprising: It is a figure corresponding to FIG. FIG. 4 is an enlarged view showing a part of the cutout recess in FIG. 3, and is a view after fillet welding in a groove portion. It is a figure which shows the fatigue improvement structure by 3rd Embodiment, Comprising: (a) is the figure before the fillet weld in a groove part, (b) is the figure after the fillet weld in a groove part.

  Hereinafter, a fatigue improving structure of a lateral rib according to an embodiment of the present invention and a steel deck using the same will be described with reference to the drawings.

(First embodiment)
As shown in FIG. 1, the structure for improving fatigue of lateral ribs according to this embodiment is applied to a steel deck 1 of a road bridge. That is, this road bridge is composed of a substructure consisting of a foundation and a pillar (not shown), steel main girders 2 and 2 constructed between the pillars, and an intermediate part supported between the pair of main girders 2 and 2. Steel plate slab 11 and cantilevered steel slab 12 supported on both sides of the main girder 2. The steel slab 1 (11, 12) includes a plurality of horizontal ribs 3 supported by the main girder 2 and valve ribs or plate ribs that form a plurality of vertical ribs supported by crossing the horizontal ribs 3 ( (Hereinafter, referred to as open cross-section ribs 4, 4...) And deck plates 5 (plate-like members) that are welded and fixed to the upper side of the lateral ribs 3 and the open cross-section ribs 4. .

The horizontal rib 3 is formed in a substantially upside down T-shape or plate shape having a web 3A extending vertically and a flange 3B integrated with the lower end of the web 3A. As shown in FIG. 2, a plurality of cutout recesses 3 </ b> C, 3 </ b> C,... Opened upward and extending downward are formed at predetermined intervals along the longitudinal direction of the lateral rib 3.
Here, the distance between the lateral ribs 3 and 3 is limited to a maximum of 2.5 m in the present road bridge specification. Furthermore, in the case of a structure using valve ribs or plate ribs as vertical ribs, this interval tends to be very small, such as 1.5 m or less. This is because the dimension of the valve rib is as small as about 200 mm, and the generated stress increases due to the moment caused by the wheel load. Since the height of the plate ribs is basically limited to about 13 times the plate thickness due to buckling restrictions, the height of the plate ribs is only about 150 mm in the case of a 12 mm thick plate. It is in.

  As shown in FIGS. 2, 3, 4 (a) and 4 (b), the open cross-section rib 4 is inserted in the state where the web 4 </ b> A is inserted into the notch recess 3 </ b> C of the lateral rib 3. The web 4A of the horizontal rib 3 and the open cross-section rib 4 is fillet welded along the notch recess 3C (first welded portion W1: both fillets), and the horizontal rib 3 and the open cross-section rib 4 are integrated by this welding joint. It has become. Further, the upper end edges 3a and 4a of the lateral rib 3 and the open cross-section rib 4 and the lower surface 5a of the deck plate 5 are welded on both sides (second welded portion W2 and third welded portion W3). The rib 3 and the open section rib 4 and the deck plate 5 are integrated. In FIG. 2, a part of the third welded portion W <b> 3 is omitted for easy viewing.

  The shape of the notch recess 3 </ b> C of the lateral rib 3 is determined by a road bridge specification or each road company, and has a predetermined dimension (for example, 15 to 15) than the thickness of the web 4 </ b> A of the open cross-section rib 4. It is formed in a groove shape having a width dimension larger by 35 mm). A scallop 3D is formed at the lower end of the notch recess 3C. The size of the scallop 3D is also determined by the above document, but is larger than the flange 4B of the open section rib 4.

  In addition, a semicircular cutout 31 is formed in the cutout recess 3C of the lateral rib 3 at a position on the deck plate 5 side (upper side) above the scallop 3D at the other side edge 3c. A groove portion 32 is provided on the upper edge of the cutout recess 3C above the semicircular cutout portion 31 (see FIG. 5). The semicircular cutout portion 31 has a cutout surface formed into a curved surface having a predetermined radial dimension (for example, 50 mm), and is disposed at a predetermined interval at a position close to the groove portion 32.

  Further, as shown in FIG. 5, the groove portion 32 is set to be smaller than the thickness dimension t of the lateral rib 3, and is, for example, a groove dimension that is approximately ½ (half) of the thickness dimension t of the lateral rib 3. Can be set to Then, after filling the groove, a turn weld that secures a predetermined leg length is formed at the end (4D) of the scalloped portion of the lateral rib 3.

Next, the fatigue improving structure of the lateral rib configured as described above and the action of the steel deck using the same will be described with reference to the drawings.
As shown in FIGS. 4A and 4B, the bending stress acting on the deck plate 5 can be reduced by providing the semicircular notch 31 at the side edge of the notch recess 3C in the lateral rib 3. As a result, it is possible to prevent fatigue cracks generated from the toe portion P of the lateral rib 3 on the deck plate 5 side. Moreover, since the compressive stress which acts on the 3rd weld part W3 of the deck plate 5 and the horizontal rib 3 can be reduced, the fatigue crack from the toe which generate | occur | produces in this 3rd weld part W3 can be prevented. .
Since the groove portion 32 is provided at the upper end of the notch recess 3C, the tensile stress acting on the welding root portion R between the deck plate 5 and the lateral rib 3 can be reduced. Fatigue cracks that occur in the root portion R on the plate 5 side can be prevented.

As described above, in this embodiment, since both compressive stress and tensile stress can be dealt with, the deck plate 5 and the lateral rib 3 in which both bending of compression and tension occur depending on the position of the wheel of the traveling vehicle. This is particularly suitable for the steel slab 1 as in this embodiment provided with a welded portion (third welded portion W3).
Further, since the above-described fatigue improvement effect can be exhibited without increasing the radial dimension of the semicircular notch 31, there is an advantage that the rigidity and strength required for the lateral rib 3 are not reduced. is there.

  In the structure for improving fatigue of a lateral rib according to the first embodiment and the steel deck using the same, the welded portion (third weld W3) between the lateral rib 3 and the deck plate 5 constituting the steel deck 1 is described. ), The generated stress acting on both the toe portion P and the root portion R can be reduced, and fatigue cracks from the toe portion P and the root portion R can be prevented to improve the fatigue life. Can do.

  Next, the analysis example performed in order to support the fatigue improvement structure of a horizontal rib by embodiment mentioned above and the steel deck using this is demonstrated below.

  In this analysis example, an example (FIG. 6A) targeting the lateral rib 3 having the semicircular notch portion 31 and the groove portion 32 of the above-described embodiment, a semicircular notch portion and a groove portion. When the load is applied on the deck plate 5 in each of the comparative example 1 shown in FIG. 6B and the comparative example 2 shown in FIG. 6C having only the semicircular notch 31. The generated stress (MPa) was measured to confirm the effectiveness of the present embodiment.

  Here, in FIGS. 6A to 6C, reference numeral P denotes a toe end position, reference numeral Ra denotes an end position of the root portion by the groove portion 32 according to the embodiment (hereinafter simply referred to as a first root portion), Reference numeral Rb indicates an end position (hereinafter simply referred to as a second route portion) of a route portion of the third welded portion W3 between the deck plate and the lateral rib 3.

FIG. 7 shows the results of this test example, where the horizontal axis indicates the distance (mm) along the longitudinal direction of the horizontal rib 3 of the deck plate 5 with respect to the weld toe P, and the vertical axis indicates the generated stress. (MPa).
As shown in FIG. 7, it can be seen that the generated stress decreases in the order of Comparative Example 1, Comparative Example 2, and Example. And in the comparative example 1 and the comparative example 2, in the 2nd root | route part Rb, the comparative example 1 and the comparative example 2 become the substantially same generated stress. That is, the generated stress in the toe portion P is approximately 325 MPa in the comparative example 1 and approximately 275 MPa in the comparative example 2, and therefore the generated stress is about 15% by providing the semicircular notch 31 in the comparative example 2. It can be seen that it is reduced. However, since the stress generated in the second root portion Rb is approximately 175 MPa in both the comparative example 1 and the comparative example 2, and no difference between the two is generated, only the semicircular notch 31 in the comparative example 2 is provided. It can be seen that the effect does not reach the second route part Rb.

  In contrast, in the example, the generated stress at the toe portion P is 220 MPa, and it can be confirmed that there is a stress reduction effect of about 30% or more for Comparative Example 1 and about 20% for Comparative Example 2. . Further, when the generated stresses in the second root part Rb of the comparative examples 1 and 2 and the first root part Ra of the example are compared, the comparative examples 1 and 2 are approximately 175 MPa, the example is approximately 70 MPa, and 50 % Or more stress reduction effect was confirmed. This is understood to be an effect of providing the groove portion 32 in the embodiment.

  Next, other embodiments and modifications of the lateral rib fatigue improving structure of the present invention and the steel deck using the same will be described with reference to the accompanying drawings, but the same as the first embodiment described above. Alternatively, the same reference numerals are used for the same members and parts, and the description thereof is omitted, and a configuration different from the first embodiment will be described.

(Second Embodiment)
As shown in FIG. 8, the structure for improving fatigue of a lateral rib according to the second embodiment is applied to a new steel deck 1A for a road bridge. That is, this road bridge is composed of a substructure consisting of a foundation and a pillar (not shown), a steel main girder 2 and 2 (see FIG. 1) installed between the pillars, and a pair of main girder 2 and 2. The intermediate steel deck 11 is supported, and the cantilever steel deck 12 is supported on both sides of the main girder 2. The steel slab 1A (11, 12) includes a plurality of lateral ribs 3 supported by the main beam 2, and a plurality of substantially L-shaped ribs 6, 6,. (Vertical ribs) and a deck plate 5 (plate-like member) that is welded and fixed to the upper side of the horizontal ribs 3 and the substantially L-shaped ribs 6.

As shown in FIG. 9, the lateral rib 3 is formed in a substantially upside down T-shape or diaphragm having a web 3 </ b> A extending vertically and a flange 3 </ b> B integrated with the lower end of the web 3 </ b> A, In the web 3A of the horizontal rib 3, a plurality of cutout recesses 3C, 3C,... Opened upward and extending downward are formed at predetermined intervals along the longitudinal direction of the horizontal rib 3. Here, the interval between the lateral ribs 3 and 3 is set in a range of 3 m or more and 8 m or less so that the rear wheel load of a vehicle such as a truck is only one vehicle at the main portion of the lateral rib influence line. ing.
Further, as shown in FIGS. 9 and 10, the substantially L-shaped rib 6 has a substantially L-shaped or T-shaped cross section from a web 6A extending vertically and a flange 6B continuous to the lower end of the web 6A. It is formed. This section is in principle a welded assembly member, but it may also be a rolled member.

  As shown in FIG. 10, the substantially L-shaped rib 6 has a web 6 </ b> A inserted through the cutout recess 3 </ b> C of the lateral rib 3, and the web of the lateral rib 3 and the substantially L-shaped rib 6 in this inserted state. 6A and 6A are fillet welded along the notch recess 3C (first welded portion W1), and the transverse rib 3 and the substantially L-shaped rib 6 are integrated by this welding joint. Further, the top edges 3a, 6a of the webs 6A, 6A of the lateral rib 3 and the substantially L-shaped rib 6 and the bottom surface 5a of the deck plate 5 are fillet welded (second welded portion W2, third welded portion W3). The horizontal rib 3 and the substantially L-shaped rib 6 and the deck plate 5 are integrated by this welding joint.

  The notch recess 3 </ b> C of the lateral rib 3 is larger than the plate thickness of the web 6 </ b> A of the substantially L-shaped rib 6 by a predetermined dimension (for example, 15 to 35 mm), and is larger than the width dimension of the flange 6 </ b> B of the substantially L-shaped rib 6. Is also formed in a groove shape having a sufficiently small width dimension. A scallop 3D is formed at the lower end of the notch recess 3C. Further, the substantially L-shaped rib 6 and the lateral rib 3 are such that one side surface 6b of the web 6A of the substantially L-shaped rib 6 is close to the side edge 3b of one of the notches n3C (left side in FIG. 10). The web of the substantially L-shaped rib 6 with the other side surface 6c of the web 6A away from the other side edge 3c of the notch recess 3C (the right side in FIG. 10) by the same distance as the predetermined dimension. One side surface 6b of 6A and the web 3A of the lateral rib 3 are welded together along one side edge 3c of the cutout recess 3C.

  In addition, a semicircular cutout n31 is formed in the cutout recess 3C of the lateral rib 3 at the position on the deck plate 5 side (upper side) above the scallop 3D at the other side edge 3c. A groove portion 32 is provided on the upper edge end of the cutout recess 3C above the semicircular cutout portion 31. The semicircular cutout portion 31 has a cutout surface formed into a curved surface having a predetermined radial dimension (for example, 50 mm), and is disposed at a predetermined interval at a position close to the groove portion 32.

  Further, the groove portion 32 has a straight groove surface and is set to be smaller than the thickness dimension t (see FIG. 5) of the lateral rib 3, for example, approximately ½ (half the thickness dimension t of the lateral rib 3). ) Groove dimensions.

(Third embodiment)
As shown in FIGS. 11 (a) and 11 (b), the structure for improving fatigue of lateral ribs according to the third embodiment is an example applied to reinforcement and repair of an existing steel deck 1, and a groove portion 32. The shape is formed in a J shape or a semi-U shape.
In this case, a semicircular notch 31 and a groove 32 are provided for the existing lateral rib 3. At this time, since the groove portion 32 is J-shaped or semi-U-shaped, repair welding (reference numeral W4 in FIG. 11B) is possible even under overhead construction conditions. The same fatigue improving structure as that of the embodiment can be realized. Therefore, the generated stress acting on both the toe portion P and the root portion R can be reduced, and fatigue cracks from the toe portion P and the root portion R can be prevented to improve the fatigue life. it can.

  As mentioned above, although the fatigue improvement structure of the horizontal rib by this invention and embodiment of the steel deck using this were demonstrated, this invention is not limited to said embodiment, The range which does not deviate from the meaning It can be changed as appropriate.

For example, in this embodiment, the open cross-section rib 4 and the substantially L-shaped rib 6 are employed as the vertical rib, but the present invention is not limited to this.
Further, the size of the semicircular cutout portion 31 and the groove portion 32 can be appropriately set based on conditions such as the thickness dimension and pitch of the lateral rib 3.

  In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the spirit of the present invention, and the above-described embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Steel deck 2 Main girder 3 Horizontal rib 3A Web 3B Flange 3C Notch recessed part 4 Open cross-section rib (vertical rib)
5 Deck plate (plate-like member)
6 L-shaped rib (vertical rib)
31 Semi-circular cutout portion 32 Groove portion t Thickness dimension of lateral rib P Stop end portion R Route portion Ra First route portion Rb Second route portion

Claims (6)

Used in a welding structure comprising a plurality of horizontal ribs, a plurality of open-section vertical ribs that are supported across the horizontal ribs, and a plate-like member that is welded and fixed to the upper side of the horizontal ribs and the vertical ribs A structure for improving fatigue of lateral ribs,
The horizontal rib has at least a web extending vertically, and the web is formed with a plurality of cutout recesses that open upward and extend downward.
A semicircular cutout is formed on one side end surface of the cutout recess, and a groove is provided at the upper edge of the cutout recess above the semicircular cutout. Fatigue improvement structure of horizontal ribs.   The structure for improving fatigue of a lateral rib according to claim 1, wherein the groove portion is set to be larger than ½ of the thickness dimension of the lateral rib. The welded structure is an existing structure,
3. The structure for improving fatigue of a lateral rib according to claim 1, wherein the structure is used for repairing the existing structure by providing the semicircular cutout portion and the groove portion. 4. A steel slab using the structure for improving fatigue of a lateral rib according to any one of claims 1 to 3,
The plurality of lateral ribs are supported by the main beam,
A steel slab using a structure for improving fatigue of a lateral rib, wherein the plate-like member welded and fixed to the upper side of the lateral rib and the longitudinal rib is a deck plate. Using the structure for improving fatigue of a lateral rib according to any one of claims 1 to 3,
A steel floor comprising a plurality of horizontal ribs supported by the main girder, a plurality of vertical ribs supported crossing the horizontal ribs, and a deck plate welded and fixed to the upper side of the horizontal ribs and the vertical ribs Version,
The lateral rib has at least a web extending vertically, and the web is formed with a plurality of notches that open upward and extend downward.
The vertical rib has a substantially inverted T-shaped or L-shaped cross section from a vertically extending web and a flange continuous to a lower end portion of the web, and the flange at a position corresponding to the notch of the lateral rib is Notched and formed,
Fatigue improvement of horizontal ribs characterized in that the webs of the horizontal ribs and the vertical ribs are welded together along the notches in a state where the webs of the vertical ribs are inserted through the notches of the horizontal ribs. Steel deck using structure.   The steel slab using the structure for improving fatigue of lateral ribs according to claim 5, wherein the interval between the lateral ribs is set in a range of 3 m or more and 8 m or less.

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