Bridges – Deck
Reexamination Certificate
2003-03-25
2004-09-21
Pezzuto, Robert E. (Department: 3671)
Bridges
Deck
C014S077100
Reexamination Certificate
active
06792638
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a structure of a floor slab bridge in a bridge built up in a river or on land, and more particularly to a structure of a floor slab bridge in which a columnar H-shaped steel is used as a main girder material.
2. Related Art
A floor slab bridge is disclosed by Japanese Patent Application Laid-Open Publication No. H09-221717 as typically illustrated in its
FIGS. 1 and 2
, in which steel sheet piles
11
are used as a bottom plate, T-shaped steels or H-shaped steels (main girder member
13
) are welded to the steel sheet piles
11
such that the T-shaped steels or H-shaped steels are spacedly arranged thereon. Adjacent steel sheet piles
11
are joined by pawls
12
disposed at left and right side end faces of each steel sheet pile
11
. Concrete is placed in a space between an upper flange of each T-shaped steel or H-shaped steel and the steel sheet pile
11
through a concrete inlet port which is formed between the upper flanges of each T-shaped steel or H-shaped steel so that a lower concrete layer is formed, and concrete is placed on the upper flange so that an upper concrete layer is formed, wherein the upper concrete layer is to be joined with the lower concrete layer through the concrete inlet port.
Similarly,
FIG. 5
of the above publication shows a floor slab bridge in which a plurality of T-shaped steels or H-shaped steels are arranged in side-by-side relation on a bottom plate
3
composed of a single steel plate and concrete is placed thereon.
In those floor slab bridges, a side plate
16
is applied to the outer side surface of the side concrete layer placed on the outer side surface of the leftmost or rightmost T-shaped steel or H-shaped steel, and in the floor slab bridge shown in
FIGS. 1 and 2
, a PC steel material
18
is pierced through a web plate formed of T-shaped steel or H-shaped steel, which are arranged in a side-by-side relation, a lower concrete layer and a block which is called a cross girder
19
, from the outer side surface of the side plate
16
. Both ends of the PC steel material
18
are fastened at the outer side surfaces of the side plates
16
, and play at the joint part of the pawl
12
is set to a maximum, thereby applying a pre-stress to the concrete layer. Necessarily, the PC steel material
18
used as this pre-stress means is left in its exposed state at the fastening parts on both ends at the outer side surfaces of the side plates
16
.
In the above-mentioned conventional structure(s), the bottom plate is formed by the steel sheet piles
11
, and the T-shaped steels or H-shaped steels are spacedly arranged in side-by-side relation on the bottom plate as in the manner mentioned above. Play at the joint part of the pawl
12
of the steel sheet pile
11
is set to a maximum. After the concrete is cured, the PC steel material
18
is fastened at the outer side surfaces of the side plates
16
, thereby applying a pre-stress to the concrete layer. The PC steel material
18
pierces through the cross girder
19
, with play, thus enabling a fastening which can apply the pre-stress. Accordingly, the PC steel material
18
is not joined with the concrete at all. This means that the PC steel material
18
does not function as a concrete reinforcement.
Therefore, if a vertical load (live load) attributable to a passage of vehicles, etc. is applied to the floor slab bridge, a shearing force would act on the concrete layer which would induce cracking of the concrete layer.
Moreover, since the PC steel material
18
is fastened at the outer side surfaces of the two side plates
16
, the load is totally applied to the fastening parts of the side plates
16
, thus resulting in a collapsing and/or twisting of the side plates
16
.
In addition, since the fastening parts are exposed from the side plates
16
, i.e., from the concrete layer, the fastening parts become rotten due to wind, rain or the like so as to degrade their original function and to spoil the outer appearance of the floor slab bridge.
Moreover, it is very troublesome to fillet weld each and every T-shaped steel or H-shaped steel over its entire length to the bottom plate
3
and the steel sheet piles
11
at constant intervals. Thus, the labor time is increased and the cost is increased, too.
The present invention has been accomplished in view of the above problems.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a structure of a floor slab bridge which can be properly formed by forming a main girder structure using commercially available columnar H-shaped steels and applying concrete thereto.
In order to achieve the above object, according to one aspect of the present invention, there is provided a structure of a floor slab bridge comprising a plurality of columnar H-shaped steels each of which includes a web plate having at an upper end thereof an upper flange and at a lower end thereof a lower flange, the columnar H-shaped steels being arranged in side-by-side relation with an end face thereof abutted with a corresponding end face of an adjacent columnar H-shaped steel, the upper flanges being smaller in width than the lower flanges so that a concrete inlet port is formed between adjacent upper flanges; a lower concrete layer formed by placing concrete in a space defined between the upper and lower flanges and between the adjacent web plates through the concrete inlet port; an upper concrete layer formed by placing concrete on the upper flange and connected to the lower concrete layer through the concrete inlet port; a horizontal iron reinforcement horizontally laid on each of the upper flanges; a suspending iron reinforcement suspended in the space through the concrete inlet port; and the horizontal iron reinforcement being embedded in the upper concrete layer and the suspending iron reinforcement being embedded in the lower concrete layer.
By the horizontal iron reinforcement and the suspending iron reinforcement suspended therefrom, the joining strength between the upper concrete layer and the lower concrete layer, particularly the lower concrete layer demarcated by the web plate is properly reinforced, thereby providing sufficient strength to the entire floor slab bridge.
Thus, the shearing resisting force of the concrete against the live load is increased to effectively prevent cracking.
The columnar H-shaped steels generally of JIS specifications each having an upper flange which is cut in such a manner so as to have a predetermined width are arranged in a side-by-side relation between adjacent bridge legs with the adjacent lower flanges abutted with each other, and concrete is placed thereon. Merely by doing so, a floor slab bridge can be constructed at a low cost and with a reduced amount of labor time.
According to another aspect of the present invention, there is provided a structure of a floor slab bridge comprising a plurality of columnar H-shaped steels each of which includes a web plate having at an upper end thereof an upper flange and at a lower end thereof a lower flange, a joining plate made of a steel material being interposed between every adjacent pair of lower flanges, left and right end faces of each of the joining plates being in abutment relation with corresponding end faces of lower flanges of the adjacent left and right columnar H-shaped steels, a concrete inlet port being formed between every adjacent pair of upper flanges with the help of the joining plate; a lower concrete layer formed by placing concrete in a space formed between the upper and lower flanges and between the adjacent web plates through the concrete inlet port; and an upper concrete layer formed by placing concrete on the upper flange and connected to the lower concrete layer through the concrete inlet port.
By employment of the joining plate, the time and labor for dimensioning the upper flange smaller in width than the lower flange can be eliminated. The columnar H-shaped steels of JIS specifications can be used as they are. Accordingly, a floor slab bridge can be cons
Saito Fumihiro
Tokuno Mitsuhiro
Tsuda Kazutoshi
Asahi Engineering Co. Ltd.
Pechhold Alexandra K.
Pezzuto Robert E.
Wenderoth , Lind & Ponack, L.L.P.
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