JP2006070570A - Vertical rib for steel floor slab and its installation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a U rib for a vertical rib of a steel floor slab for easily inspecting even the existence of a fatigue crack, while securing a quality assurance of construction. <P>SOLUTION: The U rib 20 for the vertical rib of the steel floor slab is divided into a pair of side plates 21 and a bottom plate 21 separate from the side plates. An upper end part in the width direction of the respective side plates 21 is welded to a deck plate 10 of the steel floor slab from both sides of the outside and inside by fillet welding. A second fitting part 22a arranged in both end parts in the width direction of a bottom plate 22, is fitted to a first fitting part 21a arranged in a lower end part in the width direction of the respective side plates 21, to thereby extend the bottom plate 22 between the mutual end parts of the pair of side plates 21. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steel deck using U ribs as vertical ribs in a steel bridge or the like.

Steel floor slabs have a weight that is 1/2 to 1/3 that of RC slabs. Therefore, the floor structure is advantageous for long span bridges that are greatly affected by dead loads, and the weight of superstructure can be reduced. Therefore, it can reduce the burden on the substructure and is excellent in earthquake resistance. Also, the steel floor slab can be manufactured at the factory and assembled locally, so construction can be shortened.
On the other hand, since a relatively thin steel plate is assembled by welding, the structure is likely to be deformed by welding, and careful attention is required. Moreover, since the steel slab has a structure that directly supports an automobile load, it is easily damaged by fatigue and ensuring durability is an important issue.

As shown in FIG. 4, the steel deck is stiffened by providing vertical ribs and horizontal ribs on the bottom surface of the deck plate and paved on the top surface. It has a supported structure. It is structurally advantageous to synthesize the steel deck with the main girder, and in addition to the box girder form as shown in FIG. 4, the I girder type steel deck slab is also frequently used. The intersecting portion of the vertical rib and the horizontal rib must have a structure that can reliably transmit the shearing force from the vertical rib to the horizontal rib. Moreover, as shown in FIG. 4, the vertical rib penetrates the abdominal plate of the horizontal rib, unless the bridge girder is attached to the end cross girder or the vertical rib cross section changes with the horizontal rib as a boundary. It is desirable to make it continuous. At locations where weld lines are concentrated, such as at the intersections of vertical ribs and horizontal ribs, welding is carried out in consideration of the structure of the intersections, how to take scallops, the welding size, and the like. Recently, a rationalized structure has been adopted in which the U-rib is increased in size or the deck plate is increased in thickness to increase the cross-sectional performance of the floor assembly to reduce stress and fatigue damage.

As the vertical ribs of the steel deck, flat steel, valve plates, U ribs and the like are frequently used. In particular, U-ribs (traffribs) have become mainstream in recent years because they can increase the interval between cross beams.
To weld vertical ribs with open cross-sections such as flat steel and valve plates to the deck plate, fillet welding can be performed from both sides. However, in the case of a U-rib having a closed cross section, it is unavoidable to perform one-side welding from the outside. Therefore, as shown in FIG. 6A, for example, when the plate thickness is 6 mm or more, a groove is provided to perform groove welding. In terms of workability, fillet welding is better, but since welding cannot be performed from the inside, groove welding is used that allows for sufficient penetration. In FIG. 6A, the left side of the U rib is shown in a state before welding, and the right side is shown in a state after welding (the same applies to FIG. 6B).
Registered Utility Model No. 3064047

Due to the increase in traffic of large vehicles in recent years and the problem of overloading, fatigue damage of steel slabs has become more obvious than before.
FIG. 7 exemplifies the main occurrence points of fatigue cracks in the steel deck, and details thereof are as follows.
(1) U-rib field butt welds directly under the wheel load (2) Vertical rib fillet welds consisting of deck plates and U ribs (3) Deck plate and transverse rib field welds, scallop fillet welds (4 ) Fillet welded part of deck plate and vertical stiffener (5) Welded part of corner plate (6) Scallop and turning welded part of crossing of transverse rib and longitudinal rib (7) Fillet welded part of end of longitudinal rib ( About the fatigue crack which generate | occur | produces on the surface of 1)-(7), it can detect by careful visual inspection and can take some countermeasures. However, in the one-side fillet welded portion between the deck plate and the U-rib of (2), a fatigue crack is generated from the inside of the closed cross section as shown by the phantom line in FIG. As shown in FIG. 6A, the same applies to the case where the portion (2) is replaced with one-side fillet welding and one-side groove (groove) welding. For this reason, how to carry out inspection, diagnosis, countermeasures, etc. is a big problem. In particular, it has been reported that a fatigue crack generated from the inside penetrates the deck plate and greatly deforms the floor slab, and countermeasures are urgently required.
At present, we are trying to suppress the occurrence of fatigue cracks by adopting a rationalized structure (thickening the thickness of the deck plate, increasing the thickness of the U-rib, or providing groove and groove welding). It ’s hard to say.

The problems when using U ribs for the vertical ribs of steel decks are summarized as follows.
a) Construction is not easy.
b) Quality assurance is not easy with welding on one side only.
c) Visual inspection is not possible.
d) Non-destructive inspection methods have not been established.
e) Repair and reinforcement measures are not easy.

  In order to solve the above problems, a vertical rib for a steel floor slab according to the present invention has a pair of side plates and a bottom plate that is separate from these side plates, and extends in one direction. One end portion in the width direction orthogonal to the longitudinal direction is joined to the deck plate of the steel floor slab, the first fitting portion is provided at the other end portion, and the first fitting is provided at both end portions in the width direction of the bottom plate. A second fitting portion to be fitted to the joint portion is provided, respectively. As a result, the side plate can be joined to the deck plate not by one-side welding only from the outside but by both-side welding from the outside and inside, thereby ensuring the quality assurance of the welding operation. Further, when performing maintenance, the bottom plate can be removed as needed, the inside can be visually inspected, non-destructive inspection is possible, and the presence or absence of a fatigue crack can be easily and reliably confirmed. As a result, it is possible to easily take measures for repair and reinforcement.

  The steel deck according to the present invention is formed by stiffening a deck plate with vertical ribs made of U ribs, and the vertical ribs are a pair of side plates and a bottom plate that is separate from the side plates. One end portion in the width direction orthogonal to the longitudinal direction of each side plate is welded on both sides to the deck plate of the steel floor slab, and the bottom plate is detachably bridged between the other end portions of the side plates. It is characterized by that. As a result, the quality assurance of the welding work can be ensured as described above. In addition, the presence or absence of fatigue cracks can be easily and reliably confirmed, and repair and reinforcement measures can be easily taken.

  Here, it is desirable that the pair of side plates be connected so that the bottom plate is pulled in the width direction. As a result, an interlocking effect appears, the side plate and the bottom plate can be firmly connected, and the required rigidity can be ensured reliably.

  The installation method of the vertical ribs for steel slabs according to the present invention includes a pair of side plates and a separate bottom plate as constituent members of U ribs to be vertical ribs for steel slabs, One end portion in the width direction of the side plate is welded to the deck plate of the steel floor slab from the outside and the inside, and then both ends in the width direction of the bottom plate are attached to the first fitting portion provided at the other end portion in the width direction of each side plate. The second fitting portion provided in the portion is fitted, and thereby, the bottom plate is bridged between the other end portions of the pair of side plates. As a result, the quality assurance of the welding work can be ensured as described above. In addition, the presence or absence of fatigue cracks can be easily and reliably confirmed, and repair and reinforcement measures can be easily taken.

  When joining the side plates to the deck plate, the interval between the first fitting portions of the pair of side plates is set to be slightly smaller than the interval between the second fitting portions at both ends of the bottom plate, It is desirable that the bottom plate is pulled in the width direction by the pair of side plates. As a result, the side plate and the bottom plate can be firmly connected by the interlocking effect, and the required rigidity can be reliably ensured.

  According to the present invention, it is possible to ensure construction quality assurance by welding on both sides. In addition, the presence or absence of fatigue cracks can be checked easily and reliably, and repair and reinforcement measures can be easily taken.

Embodiments of the present invention will be described below.
As shown in FIG. 1, a steel deck of a steel bridge includes a deck plate 10 and vertical and horizontal ribs 20 and 30 for stiffening the deck plate 10. The longitudinal ribs 20 extend in the direction of the bridge axis perpendicular to the paper surface of FIG. 1 and are arranged in parallel (only one is shown in FIG. 1) spaced apart in the bridge width direction (left and right) (see FIG. 4). The horizontal rib 30 extends to the left and right so as to be orthogonal to the vertical rib 20. The horizontal rib 30 is formed with an inverted trapezoidal through recess 31, through which the vertical rib 20 passes. Scallops 32 are formed at both corners of the through recess 31.

  The vertical rib 20 is configured by a U rib. That is, it is composed of a pair of side plates 21 and a bottom plate 22 and has a U-shaped cross section. As shown in FIG. 2, the side plate 21 and the bottom plate 22 of the vertical rib 20 are divided and separate from each other. Each of the plates 21 and 22 is formed of a rolled steel plate that extends long in the bridge axis direction.

As shown in FIG. 1, the pair of side plates 21 are arranged in parallel so as to face each other on the left and right. These side plates 21 are inclined so that the width direction (height direction) is directed substantially upward and downward and approach each other downward. The upper end portion (one end portion) of each side plate 21 is abutted against the lower surface of the deck plate 10 and is fillet welded on both sides. That is, the side plate 21 is welded not only from the outside (the side opposite to the other side plate 21 side) but also from the inside (the other side plate 21 side).
A first fitting portion 21 a is formed at the lower end portion (the other end portion) of each side plate 21. The 1st fitting part 21a of this embodiment has comprised the nail | claw shape bent roundly from the main-body part of the side plate 21 to the inner side and the upper side.

  A bottom plate 22 is stretched horizontally between the lower ends of the pair of side plates 21. Second fitting portions 22 a are respectively provided at both left and right end portions of the bottom plate 22. The second fitting portion 22a of this embodiment has a claw shape that is rounded from the main body portion of the bottom plate 22 upward and outward. These second fitting portions 22a are fitted to the first fitting portions 21a of the left and right side plates 21 so as to be slidable in the longitudinal direction and to restrain displacement in directions other than the longitudinal direction. Thereby, the lower ends of the pair of side plates 21 are connected by the bottom plate 22.

  Here, the distance L1 (FIG. 1) between the second fitting portions 22a at both ends of the bottom plate 22 is the distance between the first fitting portions 21a of the pair of side plates 21 in the natural state before being connected by the bottom plate 22. It is slightly smaller than the interval L0 (FIG. 2). Thus, the pair of side plates 21 are connected to each other so that the bottom plate 22 is pulled in the width direction (left and right). As a result, an interlocking effect is exhibited, and the side plate 21 and the bottom plate 22 are firmly connected.

The side plate 21 with the fitting portions 21a and 22a and the bottom plate 22 can be easily manufactured by rolling or the like.
The vertical ribs 20 composed of the divided plates 21 and 22 are attached to the deck plate 10 as follows.
As shown in FIG. 2, the side plate 21 is inclined at a predetermined angle, and the upper end portion thereof is brought into contact with the deck plate 10. The inclination of the side plate 21 can be made accurate by using, for example, a contact plate having an inclined surface of the predetermined angle and placing the side plate 21 on the inclined surface of the contact plate. Then, the side plate 21 and the deck plate 10 are temporarily welded.
Next, fillet welding of the upper end of the side plate 21 is performed on the deck plate 10 from both the outside and inside. Since the side plate 21 at this stage is open not only on the outside but also on the inside, the welding operation can be easily performed from the inside, and the construction quality can be improved.
The above side plate attaching operation is sequentially performed on the left and right side plates 21. At this time, the interval L0 between the first fitting portions 21a of the pair of side plates 21 is set to be slightly larger than the interval L1 between the second fitting portions 22a at both ends of the bottom plate 22.

Next, as shown in FIG. 3, the left and right second fitting portions 21 a of the bottom plate 22 are changed to the first fitting portions 21 a of the left and right side plates 21 at the front end in the bridge axis direction (longitudinal direction). Fit each one. At this time, the lower ends of the pair of side plates 21 are brought close to each other so as to match the width of the bottom plate 20. Then, the bottom plate 22 is slid to the back side along the bridge axis, and the position of the side plate 21 and the longitudinal direction is matched.
Since the lower ends of the pair of side plates 21 tend to be separated from each other, a tensile force acts on the bottom plate 22. As a result, an interlocking effect appears. Thereafter, the side plate 21 and the bottom plate 22 are connected and fixed with bolts.

According to the split U-rib 20, since the side plates 21 are welded on both sides, not only quality assurance is easy, but also fatigue durability and welded joint grade can be greatly improved. As a result, the occurrence of fatigue cracks can be suppressed as compared with the conventional integrated U-rib. Further, fillet welding that is simpler than groove welding can be adopted, and the welding operation can be simplified.
Since the interlocking effect is expressed in the pair of side plates 21 and the bottom plate 22, these plates 21 and 22 can be firmly connected to each other. As a result, the required shape and rigidity of the vertical rib can be ensured. It is easy to cope with large U-rib cross sections.
In maintenance management, the bottom plate 22 can be easily removed by sliding it as necessary. Thereby, the inside of a U rib can be easily inspected visually. By performing sufficient construction management at the time of the above welding, only the surface crack at the toe portion of fillet welding can be a problem, and the inspection work can be further facilitated. Nondestructive inspection can also be easily performed. If there is a crack or the like, it can be surely detected before the appearance of an external change, and appropriate measures can be taken at an early stage. As this countermeasure, the repair / reinforcement method implemented for the cruciform fillet welded joint can be applied.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, the 1st fitting part of a side plate and the 2nd fitting part of a bottom plate should just engage both so that isolation | separation is possible, and can employ | adopt various shapes. It is not limited to the type of sliding and fitting in the longitudinal direction. Various forms such as fitting to the first fitting portion can be adopted.
For welding the side plate to the deck plate, groove welding may be used instead of fillet welding.

  The present invention is applicable to a steel deck of a steel bridge, for example.

It is a front view of the principal part of the steel deck according to one embodiment of the present invention. It is a front view which shows the construction procedure of the said steel slab in the state which joined a pair of side plate to the deck plate. It is a disassembled perspective view of the vertical rib which consists of the division | segmentation U rib of the said steel deck. It is a perspective view which shows an example of a general steel bridge. It is a front view which shows another example of a general steel bridge. It is a front view which shows the U-rib of the conventional one side groove | channel (groove) welding system. It is a front view which shows the U-rib of the conventional one side fillet welding system. It is the perspective view which illustrated the main generating part of the fatigue crack of a steel deck.

Explanation of symbols

10 Deck plate 20 Vertical rib (U rib)
30 horizontal rib 31 penetrating recess 32 scallop 21 side plate 22 bottom plate 21a first fitting portion 22a second fitting portion L1 distance between both second fitting portions of the bottom plate L0 between the first fitting portions of the pair of side plates in the natural state Interval

Claims (4)

Having a pair of side plates and a bottom plate separate from these side plates, extending in one direction,
One end portion in the width direction orthogonal to the longitudinal direction of each side plate is joined to the deck plate of the steel floor slab and the other end portion is provided with a first fitting portion,
A vertical rib for a steel floor slab, wherein a second fitting portion fitted to the first fitting portion is provided at both ends in the width direction of the bottom plate. In the steel deck that stiffens the deck plate with vertical ribs made of U ribs,
The vertical rib is divided into a pair of side plates and a bottom plate that is separate from the side plates,
One end in the width direction perpendicular to the longitudinal direction of each side plate is welded on both sides to a deck plate of a steel floor slab, and the bottom plate is detachably bridged between the other end portions of these side plates. Floor slab.   The steel floor slab according to claim 2, wherein the pair of side plates are connected so that the bottom plate is pulled in the width direction. Prepare a pair of side plates and a separate bottom plate as a component of the U rib to be the vertical rib for the steel deck,
Weld one end of each side plate in the width direction to the deck plate of the steel floor slab from the outside and inside, respectively.
Thereafter, the second fitting portions provided at both end portions in the width direction of the bottom plate are fitted to the first fitting portions provided in the other end portion in the width direction of each side plate, thereby the other ends of the pair of side plates. A method of installing vertical ribs for steel slabs, characterized in that a bottom plate is bridged between the parts.

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