JP4751369B2 - U-rib steel slab - Google Patents

Description

  The present invention relates to a U-rib steel slab, and more particularly to a U-rib steel slab suitable for use in a bridge structure and capable of avoiding troubles such as cracking at a lateral rib restraining position.

  Conventionally, there are RC slabs, composite slabs, steel slabs, etc., as the floor slab structure in bridges, but steel slabs are light weight or manufactured to a certain size in the factory and installed on site It is possible, and it has many achievements because of its features such as shortening the construction period.

  However, steel slabs are easily affected by traffic loads and have a relatively thin steel plate welded structure, so that there are cases where fatigue cracks occur. In particular, there are many cases in which cracks propagate from rib intersections or slits.

In a steel floor slab structure used in a bridge structure, a vertical rib (also referred to as a truffle) is used for the steel floor slab 10 as shown in FIG. In the following, the U-rib) structure is mainly used. When using the U rib 20, it is common to install the space | interval L of the horizontal rib 30 with about 1-3 m. In the figure, 14 is a deck plate, 16 is a main beam , and 32 is a slit .

  In the case of land transportation, steel floor slabs are generally assembled on site with a length of about 10 m and a width of about 3.5 m as one block due to transportation restrictions. Even in the case of marine transportation, there are many cases in which they are manufactured in blocks of about 10m and assembled in the yard of the factory after being assembled in the factory yard due to the handling in the factory and the capacity of the crane. For this reason, as shown in FIG. 2, the field joint part 11 (including assembly in a yard) exists for every 10 m in the longitudinal direction of the completed steel deck structure.

  Further, as shown in FIG. 3, the splicing plate 12 constituting the on-site joint portion 11 is fixed by a high-strength bolt 13, and the position thereof is a position where the bending force is relatively small (1/4 of the lateral rib span L, = 2). When it is about 5 m, it is generally provided at 750 mm from the lateral rib.

  Thus, in the case of the steel slab 10 using the U rib 20 in the longitudinal rib structure, the inside of the U-rib with high airtightness is basically difficult to perform coating and rust prevention treatment. In order to prevent internal corrosion due to intrusion of outside air from the necessary opening (hand hole 20H, bolt joint, etc.), as shown in FIG. 3, the periphery is welded to both ends of the U-rib 20 of the bolt joint 11 on site. A steel diaphragm (hereinafter referred to as a sealed diaphragm) 22 is provided to maintain the airtightness inside the U rib 20.

  Usually, this sealed diaphragm 22 is installed in the U-rib 20 by welding the outer periphery in the factory. The installation position of the sealing diaphragm 22 is generally about 200 to 500 mm from the joint portion 11 in order to insert the attachment plate 12 into the U-rib 20 during installation. Therefore, when the joint part 11 is 750 mm from the horizontal rib 30, the distance d between the sealed diaphragm 22 on the side close to the horizontal rib 30 and the horizontal rib 30 is generally about 250 to 550 mm. Further, the plate thickness is generally about 6 to 8 mm which is equivalent to the plate thickness of the U rib 20, but when the plate thickness of the U rib 20 is thick, a steel plate of about 12 to 19 mm may be used.

  As shown in FIG. 4, when a vertical downward force F eccentric from the center of the U rib cross section is applied to the U rib 20 near the position where the sealed diaphragm 22 is disposed by the wheel 8 or the like passing over the deck plate 14, the sealing is performed. The U-rib 20 at the position where the diaphragm 22 is disposed rotates rigidly while maintaining the cross-sectional shape, and the stress of the structural details such as the weld toe at the intersection of the lateral rib 30 and the U-rib 20 is about double. It is reported in Non-Patent Document 1.

As a cause of this, as shown in FIG. 5, the rigid rotation R of the sealed diaphragm 22 induces a horizontal displacement of the U rib bottom surface on the lateral rib surface 20 as a torsional force, and the peripheral portion of the slit 32 due to the local bending of the U rib web. It is conceivable that stress concentration occurs in the rotating welded portion (referred to as the slit portion) . Due to this stress concentration, there is a possibility that fatigue cracks may occur from structural details that can become weak points on fatigue, such as the weld toes of the slits of the transverse rib 30 and the U-rib intersection 20. An example of a crack is shown in FIG. In the figure, A is a U-rib side crack, and B is a lateral rib-side crack. These cracks are generated on both the left and right sides of the slit portion 32.

  As a method for reinforcing a steel floor slab, Patent Document 1 describes that a lightweight foamed concrete as a filler is injected into the internal space of a longitudinal rib to improve the fatigue strength of a welded joint. It is described that a reinforcing cross beam is fastened and fixed between steel main girders, a support fitting is provided at a position corresponding to the vertical rib of the reinforcing cross beam, and the vertical rib is supported by the support fitting. 3. An attachment plate having an L-shaped cross section having a height exceeding the length of the cut including the slit portion while covering the welded joint portion between the beam plate (vertical rib of the open section valve plate) and the beam plate, Although it is described that a bolt is fastened to a plate (vertical rib of an open cross-section valve plate) and a beam plate, the fastening method shown in Patent Document 3 is used for a closed cross-section vertical rib such as a U-rib that is frequently used. It is difficult to apply.

  In Non-Patent Document 1 and the like, it is pointed out that the rigidity of the sealed diaphragm has an effect.

When the U-ribs are externally restrained by horizontal ribs at regular intervals, and when the joints are restrained by a sealed diaphragm from the inside, a vertical downward twisting force eccentric from the center of the U-rib cross section acts on the U-ribs In particular, when the U-rib at the position where the hermetic diaphragm is disposed is deformed while maintaining the cross-sectional shape, the torsional force is amplified, and troubles such as cracks at the lateral rib restraining position occur. Will occur. In order to solve this problem, Non-Patent Documents 2 to 4 describe that a reinforcing member (for example, an L-shaped angle 40) for connecting the lateral rib and the lower surface of the U-rib is provided as illustrated in FIG. . In the figure, 32 is a slit and.

  Conventionally, when attaching a connection reinforcing member (for example, L-shaped angle 40), as shown in FIG. 8A, the space is closed by the hermetic diaphragm 22, and the high-strength bolt 34 or the nut 35 is tightened in the U-rib 20. Therefore, the one-side bolt 36 that can be fastened from one side is used.

JP 2001-248114 A JP 2002-173912 A JP 2006-45833 A Iguchi et al. "Static loading test before SFRC pavement construction of steel floor slab" The 60th Annual Scientific Lecture Meeting (September 2005) CS10-017, pp. 333-334 Yamamoto et al. “Measurement of actual bridge stress in transverse rib slit of steel floor slab” 61st Annual Conference of Japan Society of Civil Engineers (September 2006) I-385, pp.767-768 Takada et al. “Study on countermeasures by FEM analysis focusing on fatigue cracks at the intersection of U-rib and transverse rib of steel floor slab” 61st Annual Conference of Japan Society of Civil Engineers (September 2006) I-563, 1123 1124 Hirano et al. “Moving Wheel Load Test Report Focusing on Fatigue Cracks at U-Rib and Cross-Rib Intersections of Steel Slabs” 61st Annual Scientific Lecture (September 2006) I-564, 1125 1126

  However, one-side bolts are more expensive than ordinary bolts, and there are many unexplained parts regarding fatigue strength and durability, so attention should be paid when using them.

  The present invention has been made to solve the above-described conventional problems, and it is possible to attach and remove a reinforcing member without using a one-side bolt, and to provide a low-cost and highly reliable structure. And

The present invention includes a deck plate, a U-rib disposed on the lower surface of the deck plate, having a sealed diaphragm inside and a hand hole on the lower surface, and, as shown in FIG. Reinforcement by connecting the transverse rib 30 and the lower surface of the U-rib to reduce deformation in the direction perpendicular to the bridge axis at the periphery of the slit, the transverse rib 30 to be restrained, the slit provided between the U-rib and the transverse rib In a U-rib steel slab provided with a member (for example, L-shaped angle 40), the distance d between the lateral rib 30 and the sealed diaphragm 22 is within a predetermined range, and the distance between the hand hole 20H and the sealed diaphragm 22 is handy. The connecting portion of the lower surface of the U-rib and the connecting reinforcing member by the high-strength bolt 34 and the nut 35 is located between the hand hole 20H and the sealing diaphragm 22; By sealing diaphragm 22 is in a position not affected by the shear force between the lateral ribs 30 is obtained by solving the above problems.

  The reinforcing member can be stopped by a bolt member (for example, a high-strength bolt 34) that is used by tightening together a bolt made of a shaft portion and a head portion on which an external thread is cut, and a nut that is tapped on the inner surface.

  The predetermined distance may be 30 mm to 100 mm.

  In order to avoid the influence of the shearing force between the sealed diaphragm and the transverse rib and determine the optimum installation position of the sealed diaphragm, the distance d from the transverse rib plate thickness center to the sealed diaphragm plate thickness center is set to 0, 20, Parametric analysis was performed with 30, 50, 75, and 246 mm. In FIG. 9, the welded end (loading side) of the slit portion of the transverse rib 30 and the U-rib crossing portion 20 in FIG. 19933.4 P289 etc.) shows a graph of the positional relationship between hot spot stress (hereinafter referred to as HSS), sealed diaphragm, and lateral rib. FIG. 10 shows a Mises stress contour diagram of the U-rib surface in the loaded state of FIG. Further, FIG. 11 shows a principal stress vector diagram in the vicinity of the welded toe of the slit portion at the intersection of the lateral rib on the loading side and the U rib in the loaded state of FIG. From these examination results, the following can be said with respect to the HSS near the weld toe of the slit portion.

(1) When the sealed diaphragm is installed on the lateral rib (d = 0 mm), the HSS is minimized and tends to increase as the distance between the sealed diaphragm and the lateral rib increases. The reason for this is that the vertical displacement due to bending increases as the distance from the lateral rib increases. However, by installing the sealed diaphragm at a position where the vertical displacement is large, the rotation angle of the sealed diaphragm increases, the torsional force increases, and the HSS increases. it seems to do.

(2) In the vicinity of d = 30 mm, as shown in FIG. 9, the value of HSS increases primarily. As a cause of this, when the distance between the sealed diaphragm and the lateral rib is close to 20 to 30 mm, the distribution range of high stress on the U-rib surface is narrow as shown in FIG. As shown in FIG. 11, since the main stress direction tends to be in the direction of the bridge axis, it can be estimated that the shearing force is excellent between the sealed diaphragm and the lateral rib.

  In addition, the installation of the sealed diaphragm on the lateral rib causes a problem of a decrease in fatigue strength because the welding of the lateral rib and the sealed diaphragm becomes a cross-weld to the U-rib web. Further, if the positions of the lateral rib and the sealed diaphragm are shifted, it causes local stress concentration, which is not preferable for fatigue. In addition, it is difficult to control the accuracy of production.

  Considering these research results, workability, positional relationship with the reinforcing structure, and the like, it is determined that the sealed diaphragm is desirably positioned 30 to 100 mm from the lateral rib.

  Here, if the predetermined distance is less than 30 mm, the shearing action due to the interference between the lateral rib and the sealed diaphragm is increased. Therefore, in order to reduce the influence of the shearing force, it is better to increase the distance. On the other hand, when this distance exceeds 100 mm, the restraint effect is lowered by separating the bolt position of the lateral rib and the reinforcing member. Therefore, the influence of stress concentration on the lateral rib slit portion by the sealing diaphragm is placed at a position of approximately 250 mm. It is equivalent to the case.

  In addition, the “reachable distance” between the hand hole and the sealed diaphragm is the distance (1.5 m) from the center of the socket of a general torque wrench to the grip part + when the adult is working upward, the arm is bent slightly Assuming that the length from the shape of the time to the center of the palm (0.5 m) is about 2 m at the maximum, and preferably within 1 m, the connection work can be facilitated.

  Furthermore, in the present invention, as shown in FIG. 8B, it is possible to fasten the general bolt 34 and the nut 35 from the hand hole 20H, and it is possible to provide a low-cost and highly reliable structure.

  In addition, as for the said connection reinforcement member, as a result of measuring the stress of a horizontal rib slit part with the horizontal rib of both ends of a steel floor slab production block, and a full size test body imitating a real bridge, it was confirmed that higher stress occurred. It is possible to dispose only the first rib adjacent to the main girder, or the first and second U-ribs. This is because, as a result of measuring the stress of the lateral rib slit part with a full-scale specimen simulating a real bridge, it became clear that higher stress was generated in the first and second U ribs than in other U ribs. is there.

  Further, the following out-of-plane restraining rib can be installed on the connection reinforcing member.

  As shown in FIG. 12A, when the wheel 8 crosses the lateral rib 30, out-of-plane deformation occurs in the lateral rib 30. Thereby, it is considered that bending stress acts on the lateral rib web surface, and the stress concentration in the slit portion becomes larger. Therefore, an out-of-plane restraining rib is installed on the L-shaped angle 40 of FIG. 8A to reduce the out-of-plane bending stress of the lateral rib, thereby reducing the out-of-plane deformation of the lateral rib web surface as shown in FIG. Therefore, it is possible to further reduce the stress of the lateral rib slit portion.

  In addition, a taper and a bolt hole are provided between the connection reinforcing member and the U rib and between the U rib and the bolt member so that the connection reinforcing member can be easily installed even if the U rib steel slab has a gradient. The filler plate provided with can be inserted.

  Alternatively, in order to facilitate installation of the connection reinforcing member even if the steel deck has a gradient, the connection reinforcing member is combined with two connection reinforcing members, and one or two bolts are provided between them. Can be fixed with a book.

  According to the present invention, it is possible to work by inserting a hand into the hand hole, and the workability is good. Furthermore, since it is not necessary to use a one-side bolt for installation, a special tool is unnecessary and the bolt strength can be increased. Moreover, it can be constructed using low-cost general high-strength bolts. Therefore, a highly reliable structure can be provided at low cost. We also confirmed the workability and the stress reduction effect with a full-scale test body simulating a real bridge.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The first embodiment of the present invention has a structure similar to that of the conventional example shown in FIG. 7, and the sealing diaphragm 22 is arranged horizontally as shown in FIGS. 13A (transverse sectional view) and (B) (longitudinal sectional view). The rib 30 is installed at a position of d = 75 mm from the center of the plate thickness, and an L-shaped angle 40 for connecting the lower surface of the U-rib 20 and the side surface of the lateral rib 30 is disposed on the sealing diaphragm 22 installation side. By providing a joint portion of the mold angle 40 with the lower surface of the U rib 20 so as to avoid the space between the sealed diaphragm 22 and the lateral rib 20, a general high-strength bolt 34 and a nut 35 are utilized using the hand hole 20H of the joint portion. Is to be bolted. The high-strength bolt 34 may be a normal bolt.

  According to this embodiment, the L-shaped angle 40 can be easily joined. Further, as shown in FIG. 13B, the operator can work by inserting his / her hand into the hand hole 20H, and the workability is good. Furthermore, since it is not necessary to use a one-side bolt for installation, a special tool is unnecessary and the bolt strength can be increased. Note that the number of the high-strength bolts 34 may be two or three or more, and the positions of the high-strength bolts 34 and the nuts 35 may be upside down or left and right.

  Next, a second embodiment of the present invention will be described in detail with reference to FIGS. 14A (transverse sectional view) and (B) (longitudinal sectional view).

  In the present embodiment, a combination of two L-shaped angles 50 and 52 is used to bolt the lower surface of the U rib 20 and the lateral rib 30 using a high-strength bolt 34 and a nut 35.

  In this embodiment, after the L-shaped angle 50 is bolted to the lower surface of the U-rib 20, the L-shaped angle 52 and the lateral rib 30 are bolted, and finally the L-shaped angles 50 and 52 are bolted.

  In the present embodiment, since the two L-shaped angles 50 and 52 are used, it is easy to adjust the joining position of the U rib 20 and the lateral rib 30.

Even when the above embodiment is used in a portion where there is a slight transverse gradient or longitudinal gradient, as shown in FIG. 15A, the reinforcing member 40 and the U rib lower surface (outer surface) and the bolt 34 and the U rib lower surface (inner surface). ) Is inserted into the reinforcing member 40 by inserting a filler plate (insertion plate) 42 provided with a taper (plate thickness difference) of t ₁ to t ₂ and a bolt hole 43 as shown in FIG. Installation is possible without any special processing.

  Alternatively, as in the third embodiment shown in FIG. 15, the horizontal rib 30 and the L-shaped angle 52 can be joined with one high-strength bolt 34 and the nut 35 so as to be able to cope with a large transverse gradient or longitudinal gradient. .

  When fixing with two bolts, bolts on the side of the horizontal rib of the L-shaped angle 52 as in the fourth embodiment shown in FIGS. The bolt holes on the joint surface can be structured to be able to rotate between members as bolt holes 53 provided with a play that allows rotation, such as a curved long hole.

  In the first to fourth embodiments, since a simple L-shaped angle is used for reinforcement, the configuration is simple. Note that the L-shaped angle 40 may be formed by joining two plates by welding to produce an L-shaped or similar connection reinforcing member.

  Further, the structure of the reinforcing member is not limited thereto, and an L-shaped angle 60 provided with ribs 61 can be used as in the fifth embodiment shown in FIG.

  Alternatively, two L-shaped angles 60 and 62 provided with ribs 61 as shown in FIG. 20 as in the sixth embodiment shown in FIGS. 19A (transverse sectional view) and (B) (longitudinal sectional view). Can also be used. The other points are the same as those of the second embodiment shown in FIG.

  In the fifth and sixth embodiments, since the ribs 61 are provided on the L-shaped angles 60 and 62, further strong connection is possible, and the ribs 61 further restrain the out-of-plane deformation generated in the lateral ribs 30. can do.

  Note that, as in the seventh embodiment shown in FIG. 21, the horizontal rib 30 and the L-shaped angle 62 can be joined by one high-strength bolt 34 and the nut 35 so as to correspond to the longitudinal gradient.

  As shown in FIG. 22, the position where the reinforcing member 60 such as an L-shaped angle is provided is the first U-rib (also referred to as a first U-rib) or / and the second one from the main girder 16 where stress is higher than other U-ribs. The slit portion of the U rib (also referred to as the second rib) is effective, but is not limited thereto, and may be provided on another U rib.

Perspective view showing the shape of part of the steel deck Same side view The perspective view which similarly shows the arrangement | positioning state of a sealing diaphragm The perspective view which shows the eccentric bending which acts on the sealing diaphragm for demonstrating the conventional problem Cross-sectional view showing horizontal displacement of U-rib bottom surface A perspective view showing the occurrence of cracks (A) horizontal cross-sectional view and (B) main part vertical cross-sectional view showing an example of a conventional structure (A) Longitudinal longitudinal view showing the positional relationship of the sealed diaphragm, hand hole, and reinforcing member in the conventional structure and (B) the structure of the present invention. Diagram showing an example of the relationship between the position of the sealed diaphragm and the generated stress Similarly perspective view showing the stress state Figure showing the principal stress vector state Side view showing comparison of behavior before (B) and after (A) reinforcement by out-of-plane lateral ribs 1A is a transverse sectional view and FIG. 1B is a longitudinal sectional view showing a first embodiment of the present invention. (A) transverse sectional view and (B) principal part longitudinal sectional view showing the second embodiment in the same manner (A) Sectional drawing which shows the principal part of the modification of the said embodiment, (B) The perspective view which shows the filler plate used by this modification The principal part longitudinal cross-sectional view which shows 3rd Embodiment of this invention (A) Main part longitudinal cross-sectional view which similarly shows 4th Embodiment, and (B) Front view of L-shaped angle The perspective view which similarly shows 5th Embodiment (A) transverse sectional view and (B) longitudinal sectional view showing the sixth embodiment as well. Three views showing a reinforcing member used in the sixth embodiment A longitudinal sectional view showing a seventh embodiment of the present invention The perspective view which shows the example of the arrangement | positioning position of a reinforcement member

Explanation of symbols

10 ... Steel slab 12 ... Joint part 14 ... Deck plate 16 ... Main girder 20 ... U rib (vertical rib)
20H ... hand hole 22 ... sealing diaphragm 30 ... transverse ribs 32 ... slit preparative <br/> 34 ... high strength bolt 35 ... nut 40,50,52,60,62 ... L-shaped angle 42 ... filler plates 43, 53 ... Bolt Hole 61 ... Rib

Claims (7)

A deck plate, is disposed on the lower surface of the deck plate, a U rib having a hand hole to the sealed diaphragm and the lower surface to the interior, and the lateral ribs for constraining the U ribs externally, between the U ribs and transverse ribs In the U-rib steel slab provided with a connecting reinforcing member that connects the provided rib and the transverse rib and the lower surface of the U-rib to reduce deformation in the direction perpendicular to the bridge axis at the periphery of the slit ,
A distance between the lateral rib and the sealed diaphragm is within a predetermined range;
The distance between the hand hole and the sealed diaphragm is a reachable distance,
A U-rib steel slab characterized in that a connecting portion between the lower surface of the U-rib and the connecting reinforcing member is located between the hand hole and the sealed diaphragm.   2. The reinforcing member according to claim 1, wherein the reinforcing member is fastened by a bolt member that is used by tightening together a bolt made of a shaft portion and a head portion on which an external thread is cut, and a nut that is tapped on the inner surface. The described U-rib steel slab.   The U-rib steel slab according to claim 1 or 2, wherein the distance within the predetermined range is 30 mm to 100 mm.   The said connection reinforcement member is arrange | positioned only at the 1st or the 1st and 2nd U rib of the horizontal rib of the both ends of a steel floor slab manufacture block, and the main girder adjacent. The U-rib steel slab according to any one of 3 above.   The U-rib steel slab according to any one of claims 1 to 4, wherein an out-of-plane restraining rib is installed on the connection reinforcing member.   Tapers and bolt holes are provided between the connecting reinforcing member and the U rib and between the U rib and the bolt member so that the connecting reinforcing member can be easily installed even if the U rib steel slab has a gradient. A U-rib steel slab according to any one of claims 1 to 5, wherein a filler plate is inserted.   Even if the U-rib steel slab has a slope, the connection reinforcement member is combined with two connection reinforcement members so that the connection reinforcement member can be easily installed, and one or two bolts are provided between them. The U-rib steel slab according to claim 1, which is fixed with a book.