Mold-concrete composite crossbeam and construction method using the same

A mold-concrete composite crossbeam includes a H-steel composed of upper and lower flanges and a web connecting them; a concrete member formed in a length direction of the H-steel to expose the upper flange out but bury the lower flange and the web partially; deck plate supports installed to both upper side edges of the concrete member to support a deck plate placed thereon; a reinforcing steel bar installed around the H-steel; a mold including a bottom detachably coupled to a lower end surface of the concrete member, and sidewalls formed in parallel to both sides of the bottom and detachably coupled to both end sides of the concrete member; a lateral reinforcing member coupled across both sidewalls; a side reinforcing member installed to an outer side of the sidewalls in a length direction; and bottom reinforcing members installed across a lower surface of the bottom.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of PCT International Patent Application No. PCT/KR2006/005231, filed Dec. 6, 2006, and Korean Patent Application No. 2005-118845, filed Dec. 7, 2005, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a mold-concrete composite crossbeam, and more particularly to a mold-concrete composite crossbeam capable of effectively resisting a bending moment and a compressive stress and integrally provided with a mold to effectively place concrete. The present invention also relates to a construction method using such a mold-concrete composite crossbeam.

BACKGROUND ART

Generally, a H-steel crossbeam is widely used for supporting floor or slab acting as the ceiling of each story of a building. That is to say, as shown inFIG. 1, a H-steel crossbeam12and a slab11configure a slab structure10.

Meanwhile, the height of each story of the building is equal to the sum of the height of a room space and the height of the slab structure10. That is to say, as the height of the slab structure10is reduced, the height of each story may be decreased. Thus, as the height of the slab structure10is small, the height of a story is reduced in spite of the same story number, thereby reducing a construction cost.

The height H of the slab structure10is equal to the sum of the height H1of a H-steel crossbeam12and the height H2of a slab11. If the height H1of the H-steel crossbeam12or the height H2of the slab11is decreased to reduce the height H of the slab structure10, the slab structure10becomes weaker in its supporting force or bending resistance, which influences on the safety of the structure. Here, the reference numeral11adesignates a steel bar installed to the slab11.

In addition, if the size of the H-steel crossbeam12is decreased to reduce the height H of the slab structure10, the sectional area of the H-steel crossbeam is also decreased, thereby making the H-steel crossbeam weakened against a compressing force and a bending momentum.

In order to solve the above problems, a method for installing a deck plate14having a groove14acorresponding to an upper flange12aof the H-steel crossbeam12to the H-steel crossbeam12, and then placing concrete thereto to make a slab structure15, as shown inFIG. 2, was proposed.

The slab structure15advantageously reduces its height as much as the depth of the groove14a. This slab structure15may effectively endure the stress applied in a vertical direction A to the slab13, but regarding the stress applied in a direction B parallel to the slab13, a shear stress and a bending momentum are greatly concentrated in a region near the groove14asince the thickness of the slab13is small in the region, and also the slab structure15is weak against a compressing force.

FIG. 3is a sectional view showing a slab structure19including a stand16welded to a web12bof the H-steel crossbeam12, and a deck plate17installed to the stand16. That is to say, the slab structure is configured in a way of welding the stand16to the web12bfor installation, installing the deck plate17on the stand16, and then placing concrete thereto so that a predetermined portion of the H-steel crossbeam12is buried in the concrete.

This slab structure19is structurally stable in comparison to the slab structure ofFIG. 2. However, the slab structure19is disadvantageous in that a process for welding the stand16to the web12bis additionally required, and the structure may have seriously bad stability if the welding portion between the stand16and the web12bis not firm.

In addition, in the above slab structures, H-steel is weak against fire since it is exposed outward. That is to say, high temperature caused by the fire may be directly transferred to the H-steel, which may cause deformation of the H-steel. In order to prevent this problem, the exposed H-steel should be coated with heat-resisting material.

Meanwhile, when constructing beams and slabs in the conventional art, H-steel is connected between columns, and then a mold is installed to surround them. Thus, it causes delay of construction process and economic loss in installing the mold and also removing the mold after casting.

DISCLOSURE OF INVENTION

Technical Problem

The present invention is designed in consideration of the above problems, and therefore it is an object of the invention to provide a mold-concrete composite crossbeam capable of effectively reducing the height of story by decreasing the height of a slab structure without causing any bad influence on the safety of a building.

Another object of the present invention is to provide a mold-concrete composite crossbeam capable of effectively resisting a bending momentum and a compressive stress applied to a building.

Still another object of the present invention is to provide a mold-concrete composite crossbeam that does not require any separate heat-resistance coating or corrosion-resistance coating on a H-steel.

Further another object of the present invention is to provide a mold-concrete composite crossbeam integrally provided with a mold so that concrete may be effectively placed.

Technical Solution

In order to accomplish the above object, the present invention provides a mold-concrete composite crossbeam, comprising: a H-steel composed of an upper flange, a lower flange, and a web connecting the upper and lower flanges to each other; a concrete member formed in a length direction of the H-steel so that the upper flange of the H-steel is exposed out but the lower flange and the web are at least partially buried therein; deck plate supports installed to both side edges of an upper surface of the concrete member so as to support a deck plate placed thereon; a reinforcing steel bar installed around the H-steel; a mold including a bottom detachably coupled to a lower end surface of the concrete member, and a pair of sidewalls formed in parallel to both sides of the bottom and detachably coupled to both end sides of the concrete member; a lateral reinforcing member coupled across both sidewalls of the mold to support the sidewalls; a side reinforcing member installed to an outer side of the sidewalls of the mold in a length direction thereof; and a plurality of bottom reinforcing members installed across a lower surface of the bottom of the mold to support the lower surface.

Preferably, a plurality of buried nuts for preventing contact with concrete are provided to an end of the concrete member, and coupling bolts are inserted into a plurality of coupling holes formed in the mold and coupled to the buried nuts so as to fix the mold to the concrete member.

More preferably, extension support units extended outward in both side directions are formed on upper edges of the sidewalls of the mold to support the deck plate.

In one embodiment, the reinforcing steel bar includes a plurality of stirrup steel bars installed in a length direction of the H-steel at regular intervals to surround at least a part of the H-steel; and a plurality of tension/compression steel bars installed in parallel in a length direction of the H-steel.

In another aspect of the present invention, there is also provided a mold-concrete composite crossbeam, comprising: a H-steel composed of an upper flange, a lower flange and a web connecting the upper flange and the lower flange; a main concrete member formed in a length direction of the H-steel and having a thickness (T2) that exposes the upper flange of the H-steel out buries the lower flange and at least a part of the web therein, and a sub concrete member continuously extended from an end of the main concrete member and having a thickness (T1) relatively smaller than the main concrete member; deck plate supports installed to both side edges of an upper surface of the concrete member so as to support a deck plate placed thereon; a reinforcing steel bar installed around the H-steel; a mold including a bottom detachably coupled to a lower end surface of the concrete member, and a pair of sidewalls formed in parallel to both sides of the bottom and detachably coupled to both end sides of the concrete member; a mold including a pair of sidewalls detachably coupled to both end sides of the main concrete member and both sides of the sub concrete member; a lateral reinforcing member coupled across both sidewalls of the mold to support the sidewalls; and a side reinforcing member installed to an outer side of the sidewalls of the mold in a length direction thereof.

Preferably, the reinforcing steel bar includes a plurality of stirrup steel bars installed in a length direction of the H-steel at regular intervals to surround at least a part of the H-steel; and a plurality of tension/compression steel bars installed in parallel in a length direction of the H-steel.

More preferably, the stirrup steel bars include a lower steel bar unit extended across a lower portion of the lower flange of the H-steel; an intermediate steel bar unit extended upward from both ends of the lower steel bar unit; and an extension steel bar unit extended in both side directions from a front end of the intermediate steel bar unit.

In one embodiment, the extension steel bar unit may be located at a position relatively higher or lower than the upper flange of the H-steel.

In one embodiment, the stirrup steel bar may have a closed shape so that both ends of the stirrup steel bar are contacted to both sides of the web with surrounding the lower flange of the H-steel bar, whereby an upper portion of the stirrup steel bar is not buried in the concrete member but exposed out.

Also, the mold-concrete composite crossbeam according to the present invention may further include a plurality of extension members having a L-shaped section so that one ends of the extension members are fixed to both sides of the top of the stirrup steel bar and the other ends are extended outward in both side directions.

Preferably, the extension member has a front end located at a position relatively higher or lower than the upper flange of the H-steel.

In still another aspect of the present invention, there is also provided a method for constructing a building, comprising (a) installing a steel column at a position that will become a column of the building; (b) connecting both ends of a mold-concrete composite crossbeam to the steel column, the mold-concrete composite crossbeam including: a H-steel composed of an upper flange, a lower flange, and a web connecting the upper and lower flanges to each other; a concrete member formed in a length direction of the H-steel having a thickness such that the upper flange of the H-steel is exposed out but the lower flange and the web are at least partially buried therein; deck plate supports installed to both side edges of an upper surface of the concrete member so as to support a deck plate placed thereon; a reinforcing steel bar installed around the H-steel; a mold including a bottom detachably coupled to a lower end surface of the concrete member, and a pair of sidewalls formed in parallel to both sides of the bottom and detachably coupled to both end sides of the concrete member; a lateral reinforcing member coupled across both sidewalls of the mold to support the sidewalls; a side reinforcing member installed to an outer side of the sidewalls of the mold in a length direction thereof; and a plurality of bottom reinforcing members installed across a lower surface of the bottom of the mold across the lower surface; (c) placing a deck plate on the deck plate supports; (d) installing a steel bar on the deck plate; (e) putting concrete on the deck plate and the mold of the composite crossbeam to place and cure beam and slab; (f) dismantling the mold of the composite crossbeam.

Preferably, extension support units extended outward in both side directions are formed on upper edges of the sidewalls of the mold so as to support the deck plate, and the step (c) includes the step of inserting coupling bolts through coupling holes formed in the extension support units and through holes formed in the deck plate and then coupling the coupling bolts to buried nuts.

More preferably, the method for constructing a building according to the present invention further includes the steps of installing a prefabricated column mold composed of a plurality of sub mold bodies to surround the steel column; and coupling the mold to an opening of the sub mold body.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 4is a side view showing a mold-concrete composite crossbeam according to a preferred embodiment of the present invention.

Referring toFIG. 4, the mold-concrete composite crossbeam of the present invention includes a H-steel20, reinforcing steel bars installed around the H-steel20in its length direction, a concrete member40, and molds80detachably installed to both ends of the concrete member40.

FIGS. 5aand5bschematically show only the concrete crossbeam of the mold-concrete ofFIG. 4except the mold,FIG. 6is a sectional view taken along the line A-A′ ofFIG. 4,FIG. 7is a sectional view taken along the line B-B′ ofFIG. 4, andFIG. 8is a sectional view taken along the line C-C′ ofFIG. 4. Referring toFIGS. 5ato8together, the H-steel20is composed of an upper flange21and a lower flange22arranged in parallel, and a web23for interconnecting the upper and lower flanges21,22.

Preferably, a stud22aburied in the concrete member40may be protruded on the lower flange22of the H-steel20. This stud22aplays a role of more firmly coupling the H-steel20and the concrete member20.

More preferably, a plurality of through holes (not shown) are formed in the web23of the H-steel20so that the placed concrete may penetrated therein to enhance an adhesion force of the concrete member40.

Selectively, a reinforcing plate24may be added to a region where the upper flange21and the web23of the H-steel20meet, so as to endure excessive loads during construction.

The reinforcing steel bar becomes a frame supporting the mold-concrete composite crossbeam, and it may have various arrays. In this embodiment, the reinforcing steel bar includes still up steel bars30installed at regular intervals in a length direction of the H-steel20.

The stirrup steel bars30are installed to surround the H-steel20at regular intervals in a length direction of the H-steel20. Preferably, the stirrup steel bars30include a lower steel bar unit31extended across the bottom of the lower flange22of the H-steel20, intermediate steel bar units32extended upward from both ends of the lower steel bar unit31, and extension steel bar units33extended in a side direction, more preferably outward in both side directions, from the top of the intermediate steel bar units32.

The stirrup steel bars30play roles of regularly dispersing the compressing force, applied in a length direction of the H-steel20, over the cross section of the H-steel20, and also resisting the shear stress applied perpendicularly to the cross section.

The stirrup steel bars30may be installed so that they are partially buried in the concrete member40as shown in the drawings. In this case, the lower steel bar unit31is buried in the concrete member40, and the intermediate steel bar units32are buried in the concrete member40so that their upper portions are partially exposed. In addition, the stirrup steel bar30may also be installed near both ends of the crossbeam where the concrete member40is not formed.

In addition, the reinforcing steel bar includes a plurality of tension/compression steel bars60,70arranged in a length direction of the beam. The tension/compression steel bars60,70become supports that resist tension and compression stresses applied to the mold-concrete composite crossbeam.

Preferably, the tension/compression steel bars include a plurality of buried tension/compression steel bars60(hereinafter, referred to as ‘buried steel bars’) at least partially buried in the concrete member40, and exposed tension/compression steel bars70(hereinafter, referred to as ‘exposed steel bars’) not buried in the concrete member40but exposed outward.

The buried steel bars60are arranged in a length direction between the lower flange22of the H-steel20and the stirrup steel bar30surrounding the lower flange22, and preferably installed in contact with the lower steel bar31. In addition, in the region where the concrete member40is not formed, the stirrup steel bar30may be supported in a way of being welded or coupled to the buried steel bar60.

In addition, so as to stably support the exposed portion of the buried steel bar60and/or the stirrup steel bar30not buried in the concrete member40, as shown inFIG. 5b, a base bracket34for fixing the stirrup steel bar30to the H-steel20may be further provided. Specifically, the base bracket34is a plate extended from the bottom of the lower flange22of the H-steel20in a length direction, and the stirrup steel bar30is fixed to its upper surface by means of welding or the like. In addition, both ends of the base bracket34are attached to the lower surface of the lower flange22by means of welding or the like.

As another alternative, the exposed portion of the buried steel bar60may be directly fixed to the lower flange22of the H-steel20by means of the base bracket35that traverses the lower portion of the H-steel20, as shown inFIG. 9. InFIG. 9, the stirrup steel bar is not shown for simplification.

According to the present invention, the exposed steel bar70is placed on the extension steel bar unit33of the stirrup steel bar30, when being coupled. However, in this case, since the exposed steel bar70is spaced far from the center of the mold-concrete composite crossbeam in both side directions, the exposed steel bar70may pass aside a column when the mold-concrete composite crossbeam is connected to the column, as explained later.

Preferably, the exposed steel bar70may be configured so that it is positioned above or below the upper flange21of the H-steel20. That is to say, the extension steel bar unit33may be positioned above or below the upper flange21of the H-steel20, and accordingly the exposed steel bar70is also positioned above or below the upper flange21.

In addition, an auxiliary cap bar36may be further provided to the mold-concrete composite crossbeam of the present invention as shown inFIG. 10for the purpose of stable coupling of the exposed steel bar70placed on the extension steel bar unit33.

The auxiliary cap bar36has a length corresponding to the distance between the exposed steel bars70positioned at both sides, and both ends of the auxiliary cap bar36are bent to surround the exposed steel bars70. Thus, both ends of the auxiliary cap bar36are arranged to surround the exposed steel bars70, and then they are combined thereto such as welding or coupling as mentioned above. In this case, it is advantageous that the exposed steel bars70are coupled in a more stable way.

The tension/compression steel bars60,70may be fixed by means of welding or coupling means such as wire, and this coupling means is not limited to the embodiments of the present invention. In addition, the configuration of the reinforcing steel bars is not limited to the embodiments, and their configuration, number and positions may be changed in various ways.

The concrete member40is integrally formed along a length direction so that the H-steel20is at least partially buried therein. Preferably, the concrete member40is formed to expose the upper flange21of the H-steel20but bury at least a part of the lower flange22and the web23.

As shown in the drawings, both ends of the H-steel20are kept exposed outward without being buried in the concrete member40, which is directed to connecting the mold-concrete composite crossbeam to a column. For this purpose, a coupling hole20amay be formed in the exposed end of the H-steel20.

More preferably, the concrete member40is formed only on a part of the center of the H-steel20. In this case, the entire weight of the composite crossbeam is greatly decreased to facilitate easier installation and construction. In the drawings, lengths of the concrete member and the mold are not limited, but suitably changed in design.

The concrete member40allows effective resistance against bending stress and compression force applied in an axial direction together with the H-steel20. In addition, the concrete member40increases a sectional area of the mold-concrete composite crossbeam so that it may effectively cope with a bending stress.

According to the preferred embodiment of the present invention, though not shown in the drawings, the concrete member40may have different widths in a length direction. That is to say, the center region of the concrete member40may have a smaller width than both end regions to which a great load is directly applied. It is directed to decreasing the entire weight of the composite crossbeam due to the reduced concrete member40, thereby facilitating easier carriage, handling and installation of the composite crossbeam.

In addition, the H-steel20is constructed so that it is buried in a slab concrete, explained later, together with the concrete member40and thus not exposed out, so there is no need of separate fire-resistant treatment. It becomes a factor of greatly improving fire resistance of a structure constructed using the mold-concrete composite crossbeam of the present invention.

Preferably, the concrete member40is formed to have a predetermined roughness on its upper surface. It is directed to enhancing a coupling force with a slab placed on its upper surface.

Though not shown in the figures, a thin steel wire or wire mesh is inserted into the concrete member40in a length direction so as to prevent cracks or damage of the concrete member.

Preferably, deck plate supports50are provided to both edges of the upper surface of the concrete member40so that a deck plate may be placed and supported thereon, as explained later. The deck plate support50includes a bracket51for supporting the deck plate, and a buried member52integrally formed with the bracket51and buried in the concrete member40.

Preferably, the brackets51are made of metal material in a strip shape, installed in a length direction of the concrete member40, and more preferably the brackets51are installed to protrude outward in both side directions from both edges of the upper surface of the concrete member40.

The buried member52is buried in the concrete member40and plays a role of fixing the bracket51.

According to the preferred embodiment of the present invention, a detachable mold80is provided to both ends of the concrete member40. This mold facilitates easier placing of concrete, and also does not require a mold installation process to a connect portion when the concrete crossbeam is connected to a column.

The mold80includes a rectangular bottom81coupled to a lower surface of the end of the concrete member40, and sidewalls82,83formed in parallel on both sides of the bottom81and respectively coupled to both sides of the end of the concrete member40, and its upper surface is opened so that concrete may be injected.

The mold80is formed using glass fiber, carbon fiber, Kevlar, or their mixture, or wound or extruded FRP fiber, and it may have several layers.

Additionally, a connection hole81a(seeFIG. 4) may be formed in an end of the bottom81of the mold. The connection hole81ais used for fixing the mold-concrete composite crossbeam to a bracket installed to a column, as explained later.

Extension supports84are formed at edges of the tops of the sidewalls82,83of the mold80so as to support the deck plate. The extension supports84are extended outward in both side directions from the tops of the sidewalls82,83, and preferably the extension supports84are integrally formed with the sidewalls. In addition, a coupling hole84ais preferably further formed in each extension support84for coupling with the deck plate positioned thereon.

In addition, a plurality of drainage holes80a(seeFIG. 4) are preferably formed in the sidewalls82,83so that water may be drained out when concrete is injected.

Though not shown in the drawings, corners where the bottom81and the sidewalls82,83of the mold80meet are preferably tapered. In this case, as explained later, the mold may be dismantled more easily and the constructed concrete beam may have smooth edges.

As shown inFIG. 7, a hollow pipe may be installed between the through holes formed in the sidewalls82,83, and a transverse reinforcing member may be inserted therein with both ends being fixed by bolts, so that the transverse reinforcing member may be removed after concrete is placed and cured.

According to the present invention, side reinforcing members92are installed to the outer surfaces of the sidewalls82,83in a length direction. The side reinforcing members92are preferably angled steel pipes, through which the transverse reinforcing members90are passed and fixed by nuts91so as to firmly support the sidewalls82,83. The transverse reinforcing members90and the side reinforcing members92prevent the sidewalls82,83of the mold from being opened outward or deformed due to the load of concrete when the concrete is placed thereon, as explained later.

In addition, the lower surface of the bottom81of the mold80is supported by a plurality of bottom reinforcing members93. The bottom reinforcing members93are installed to support the mold across the lower surface of the bottom81, and they are kept suspended on the side reinforcing members92.

That is to say, a hanging rod94vertically passing through the side reinforcing member92is positioned through the bottom reinforcing member93, and both ends of the hanging rod94are coupled to nuts95,96respectively so that the bottom reinforcing member93is suspended to the side reinforcing member92.

This bottom reinforcing member93prevents the bottom81of the jacket itself from being bent downward or deformed when concrete is placed thereon.

The side reinforcing member92and the bottom reinforcing member93may be installed in advance before the mold-concrete composite crossbeam is constructed to a column, or they may be installed after the crossbeam is connected to a column as an alternative.

Preferably, the exposed portion of the stirrup steel bar30and the buried steel bar60may be supported by the bottom reinforcing member93. At this time, as shown inFIG. 7, a coupling bolt97is installed through the bottom reinforcing member93, and then a buried nut8is coupled to an end of the coupling bolt97. The buried nut98is welded to a lower surface of the base bracket34so that the stirrup steel bar30and the buried steel bar60may be supported more stably. In this case, concrete may be placed without hanging the upper portion of the mold and supporting the lower portion of the mold.

The buried nut98is formed to surround the entire screwed portion of the coupling bolt97so that the coupling bolt is not contracted with concrete. Thus, when the mold is dismantled, the coupling bolt97may be easily released, but the nut98is still buried in the concrete member.

FIG. 8is a sectional view showing a connection portion of the mold80and the concrete member40. Referring toFIG. 8, a plurality of coupling holes are formed in the bottom81and the sidewalls82,83of the mold80, positioned in the connection portion, and a coupling bolt85is inserted therein and combined with a buried nut86buried in the concrete member40.

The buried nut86has the same configuration and function as above. Thus, the mold80is positioned so that the bottom81and the sidewalls82,83of the mold80are contacted with the lower and side surfaces of the concrete member40respectively, and then they are mutually fixed using the coupling bolt85and the buried nut86. At this time, auxiliary iron pieces87,88may be further provided for more firm and stable coupling.

Now, a method for constructing a building using the mold-concrete composite crossbeam configured as above will be explained.

The mold-concrete composite crossbeam of the present invention may be simply installed to a steel column, as shown inFIG. 11as an example.

As shown inFIG. 11, first, the mold-concrete composite crossbeam of the present invention is coupled to a steel column200. Then, a coupling plate210is installed to the steel column200, and a coupling member such as a bolt220is coupled through a coupling hole20aformed in an end of the H-steel20so that the composite crossbeam is fixed to the steel column. As another alternative, the end of the H-steel20may be coupled to the steel column200by means of welding.

At this time, the exposed steel bar70of the mold-concrete composite crossbeam is placed on the extended steel bar unit33of the stirrup steel bar30and thus relatively inclined outward in both side directions from the center of the composite crossbeam, so the exposed steel bar70is not interfered with the steel column200but passes aslant from the column as shown inFIG. 11.

The mold may be supported in various ways. For example, as shown inFIG. 11, the end of the mold80may be supported by an additional mold230installed to a region where a column is to be installed. That is to say, after the additional mold230for placing a column is installed, a support231made of such as wood is attached to the top of the additional mold230, and then the mold is placed on the support231. In this case, a coupling member such as a nail232is driven through a connection hole (not shown) formed at the end of the bottom81of the mold80so as to fix the mold80to the support231.

In addition, the H-steel20of the mold-concrete composite crossbeam may be connected to the steel column200as shown inFIG. 12. That is to say, as shown inFIG. 12, a coupling bracket200ais installed to the steel column200, and then the end of the H-steel20is connected thereto using a coupling member such as a plurality of bolts220′ and at least one coupling plate210′.

Preferably, the coupling bracket200ahas the same sectional shape as the H-steel20. As another alternative, the end of the H-steel20may be coupled to the end of the coupling bracket200aby means of welding.

Besides, as inFIG. 13that shows another embodiment of the present invention, a mold support bracket240is installed to one side of the steel column200, and then the mold80is fixed thereto. At this time, a coupling bolt101may be inserted into a connection hole (not shown) formed near the end of the bottom81of the mold so as to couple the mold with the bracket240, thereby stably fixing the mold.

The coupling bolt101is coupled to a buried nut102after passing through the connection hole formed in the bottom81of the mold80and a through hole formed in the bracket240. At this time, as explained later, when it is intended to dismantle the mold80after curing concrete, the bottom81of the mold is coupled to the lower surface of the bracket240. Reference numeral103designates a reinforcing washer.

FIGS. 14 and 15illustrate a method for coupling a mold according to another embodiment of the present invention.

FIG. 14shows a prefabricated column mold used for constructing a column. The prefabricated column mold300includes a plurality of sub-mold bodies310,320assembled with each other to surround the steel column200. The sub-mold bodies310,320may have suitable size and length in correspondence to the length of a column to be constructed. In this embodiment, it is illustrated that two sub-mold bodies310,320are assembled by a coupling means330to face each other, but the prefabricated column mold may be composed of plural, for example 4, sub-mold bodies, not limited to the above.

At least one opening340is formed in the sub-mold bodies310,320so that a mold-concrete composite crossbeam may be received therein. The opening340has a size capable of being coupled with the mold80, and a plurality of coupling brackets341a,341b,341cused for coupling with the mold80are formed at edges of the sub-mold bodies310,320having the opening340. In addition, a plurality of through holes342are formed in the coupling brackets341a,341b,341cfor coupling of a coupling bolt or the like.

More preferably, a deck plate support bracket343is formed at the top of the sub-mold bodies310,320so that a deck plate may be placed thereon, as explained later.

Referring toFIG. 15, the sub-mold bodies310,320are assembled to surround the steel column200at a position where a column is to be formed. And then, the H-steel20of the mold-concrete composite crossbeam is connected to the steel column200as described above.

At this time, the end of the mold80is coupled to the coupling brackets341a,341b,341c. Specifically, the bottom81of the mold80is coupled to the coupling bracket341a, and the sidewalls82,83are coupled to the coupling brackets341c,341b, respectively.

To couple the mold80with the coupling brackets341a,341b,341c, as shown inFIG. 15, a coupling bolt344is inserted through the connection hole formed in the end of the mold80and the through holes342formed in the coupling brackets341a,341b,341c, and then screwed with a buried nut345. At this time, in order to dismantle the mold80after curing the beam and slab, the mold80is preferably coupled to the outer sides of the coupling brackets341a,341b,341c, but not limitedly.

In addition, according to the construction method of the present invention, the lower portion of the mold may be supported in various structures. In this case, there is no need of bolt and nut coupling in the lower portion for fixing the mold. Specifically, as shown inFIG. 11, a pair of first alignment stoppers250are installed across the lower surface of the bottom81of the mold80at regular interval. These alignment stoppers250preferably employ strip rods made of carbon-glass fiber or metal with a L-shaped section.

A support bar251made of metal is installed between the first alignment stoppers250across the mold body. Preferably, a support bracket252is further provided to the support bar251so as to increase a contact area with the lower surface of the bottom81of the mold for the purpose of stable support. Both ends of the support bracket252are contacted with the first alignment stoppers250, so the movement of the support bracket252is restricted.

A first support column260is installed to a lower portion of the support bar251to support the support bar251. A concave bracket261corresponding to the shape of the support bar251is provided to the end of the first support column260so as to stably receive and support the support bar251.

FIG. 11also shows another example of the support column.

Specifically, a pair of second alignment stoppers270are installed across the lower surface of the bottom81of the mold80at regular interval. The second alignment stopper270also preferably employ strip rods made of carbon-glass fiber or metal with a L-shaped section.

A support bar271made of metal is installed across the mold80between the second alignment stoppers270. Preferably, a support bracket272is further formed on the support bar271so as to increase the contact area with the lower surface of the bottom81of the mold for the purpose of stable support. Both ends of the support bracket272are contacted with the second alignment stoppers270, so the movement of the support bracket272is restricted.

A second support column280is installed to a lower portion of the support bar271to support the support bar271. A support block281is provided to the end of the second support column280. The support block281has a width corresponding to a distance between the second alignment stoppers270, and thus the support block281is coupled between the second alignment stoppers270to restrict its movement.

As explained later, after concrete is cure, the composite mold may be dissembled with dismantling the support columns.

If the mold-concrete composite crossbeam installed as mentioned above is completely coupled with the steel column200, a deck plate400is installed thereon, as shown inFIGS. 16 and 17. Here,FIG. 16is a sectional view showing a region where the concrete member40exists, andFIG. 17is a sectional view showing a region where the mold80exists.

The deck plate400is generally made of steel material, and commonly it is manufactured and supplied integrally with a crank steel bar103. The deck plate400is placed on brackets51provided to both edges of the upper surface of the concrete member40, and on an extension support84of the mold80.

Preferably, the deck plate400is welded to the bracket51, or a coupling bolt111is subsequently passed through the coupling hole84a(seeFIG. 8) formed in the extension support84and the through hole formed in the deck plate400and then coupled to a buried nut112.

At this time, it is preferred that a reinforcing plate53(seeFIG. 16),54(seeFIG. 17) is provided to the bracket51and/or the extension support84so as to further reinforce the supporting force.

An additional steel bar is provided to the slab, and the additional steel bar preferably includes reinforcing steel bars110respectively installed to both sides of the H-steel20, and a connection steel bar120installed across the H-steel20. The connection steel bar120may be installed through a hole (not shown) formed in a web23of the H-steel20. Preferably, the connection steel bar120may be combined using wire or the like in contact with the exposed steel bar70and/or the intermediate steel bar unit32and/or the extension steel bar unit33of the stirrup steel bar30.

More preferably, the connection steel bar120is installed adjacent to the reinforcing steel bar110to play a role of transferring a compression force applied to the reinforcing steel bar110at one side to the reinforcing steel bar110at the other side. It is already known that stress may be mutually transferred among steel bars if the steel bars buried in concrete are adjacent to each other within a predetermined interval.

The deck plate400may be fixed by means of coupling between the crank steel bar103and the connection steel bar120and/or the exposed steel bar70. That is to say, the crank steel bar103is combined by wire or the like and fixed at the contact portion with the connection steel bar120and/or the exposed steel bar70. Preferably, the crank steel bar103may also be combined with the extension steel bar unit33of the stirrup steel bar30.

As another example of the present invention,FIG. 18shows the coupling state of the crank steel bar103when the extension steel bar33of the stirrup steel bar30is positioned lower than the upper flange21of the H-steel20. In this case, the crank steel bar103is coupled to the exposed steel bar70and/or the extension steel bar unit33of the stirrup steel bar30together with the connection steel bar120.

If the mold-concrete composite crossbeam is completely installed as mentioned above, additional reinforcing steel bar and mold are installed as required. Preferably, a metal lath may be installed above the deck plate only on a partial region of the slab.

After that, concrete is placed and cured in the mold and slab region. As concrete is placed, the buried nut and the lateral reinforcing member90are buried in the concrete. The lateral reinforcing member90prevents the mold from being crushed or deformed in a lateral direction due to the weight of concrete.

If the concrete for a beam is completely placed using the mold-concrete composite crossbeam as mentioned above, the cross may sufficiently endure the soil pressure, so there is no need to separately install a conventional construction such as strut.

According to the present invention, after the concrete is cured, the mold may be removed and then recycled. That is to say, the nut91and the coupling bolt97(seeFIG. 7),85(seeFIG. 8),101(seeFIG. 13),111(seeFIG. 17) at both ends of the lateral reinforcing member may be released to dismantle the mold. These coupling bolts are not contacted with concrete, so they may be easily released. In addition, the buried nuts are kept their buried state in concrete.

After the nuts and coupling bolts are released, the composite mold may be easily separated. Preferably, an existing separator is coated on the inner side of the composite mold in advance before concrete is placed thereon, so that the composite mold may be separated more easily. Selectively, a plurality of release rings (not shown) may be installed in advance to the bottom81and the sidewalls82,83of the mold80so that the mold may be easily dismantled by hooking hooks or the like in the release rings and then pulling the hooks after concrete is cured.

After concrete is cured, the deck plate400may be used as a permanent structure without being dismantled.

FIGS. 19 and 20show a mold-concrete composite crossbeam according to still another embodiment of the present invention. Here, the same reference numeral as in the former drawings designates the same component.

In the mold-concrete composite crossbeam of this embodiment, a plurality buried tubes100are installed to the bottom81of the mold80. The buried tubes100have hollow therein, and their lower ends are fixed through the bottom81of the mold80and their upper ends are extended upward. Preferably, the buried tubes100have a length so that their upper ends may be exposed over the surface of slab to be placed.

The buried tubes100are preferably installed in symmetry with the mold80. It allows the buried tubes100to support the mold in balance, as explained later.

Preferably, the buried tubes100are installed to come in contact with the lateral reinforcing member90, and they are coupled with each other so that the buried tubes100may be supported more stably.

Preferably, a through hole93acommunicated with the hollows of the buried tubes100is formed in the bottom reinforcing member93that is installed on the bottom of a region where the buried tubes100are formed, so that a hanging steel bar or wire may pass through it.

FIGS. 21 and 22illustrate the process of constructing beams and slab using the mold-concrete composite crossbeam of this embodiment. Here, reinforcing steel bars are not shown in the drawings for simplification.

First, before a composite crossbeam is connected to the steel column200, a support shape steel130is installed thereon. A support member140is installed on the support shape steel130to cross the support shape steel130, and the composite crossbeam is suspended thereto.

Specifically, the H-steel20of the mold-concrete composite crossbeam of this embodiment is coupled to the steel column200as explained above. At the same time, the mold80is suspended to the support member140using a hanging wire or steel bar150.

That is to say, the hanging steel bar150is inserted into the through holes formed at both ends of the support member140, and then passed through the buried tube100of the mold80positioned in its lower layer, then both ends of the hanging steel bar150are fixed using upper and lower nuts151,152. Preferably, both ends of the hanging steel bar150are screwed so that the upper and lower nuts151,152may be easily coupled and fixed thereto.

In addition, in order to support the mold80stably, a bottom reinforcing member93is further provided to the bottom81of the mold, and the hanging steel bar150is coupled through the bottom reinforcing member93to the lower nut152.

As mentioned above, since the composite mold is suspended in the air, there is no need of additionally installing a support such as a puncheon below the composite mold, and thus it is possible to ensure sufficient working space below the composite mold.

After that, the process of placing and curing concrete to construct beams and slab is identical to that of the former embodiment. However, when concrete is put into the mold80, the end of the buried tube100should be exposed over the upper surface of the concrete.

In case of dismantling the mold80after concrete is cured, the upper and lower nuts151,152are released to remove the hanging steel bar150. In this case, the buried tube100keeps buried in the slab concrete.

If the beams and slab are completely constructed using the mold-concrete composite crossbeam of this embodiment, beams and slab in its lower layer may be easily constructed. It is well shown inFIGS. 23 and 24. In the drawings, reinforcing steel bars are not shown for simplification.

As shown inFIGS. 23 and 24, if slab and beams of the upper layer are completely constructed using the mold-concrete composite crossbeam, another mold-concrete composite crossbeam is installed to its lower layer. At this time, additional excavation can be conducted for ground construction as required.

The mold-concrete composite crossbeam of a lower layer is connected to the steel column200in the same way as above. At this time, the mold80of the lower layer is suspended to the upper composite crossbeam structure suing a hanging wire or steel bar150.

That is to say, the hanging steel bar150is inserted into the first buried tube100positioned in the concrete of the already completed upper composite crossbeam structure, and the buried tube100′ and the bottom reinforcing member93of a composite crossbeam positioned in its lower layer are passed through the first buried tube100, and then both ends of the buried tube100′ are fixed using the upper and lower nuts151,152.

After that, concrete is placed and cured for the slab of the lower layer and the mold is dismantled in the same manner as explained above.

This construction method may be applied to all kinds of structures above or below the ground. For example, in case of constructing an underground structure, the beam and slab construction process is continuously conducted to the bottom of the underground structure. In addition, if concrete is placed and cured till the bottom of the underground structure, slab and underground walls may be constructed from the bottom.

As another alternative, it is possible that beam structure is constructed sparsely in some underground stories, not in all underground stories, and slab and beams are constructed to the other stories after concrete is completely placed for the bottom of the lowest story. At this time, so-called ‘up-up construction’ may be applied in which, while slab and underground walls are constructed from the bottom story, the structure over the ground may be constructed at the same time.

As still another alternative, so-called ‘top-down construction’ may also be applied in which, after beams or a part of slab are completely constructed for the bottom of the structure over the ground, the structure over the ground is constructed together with excavation and construction of the underground structure. Here, beams and slab for the structure over the structure are constructed together with excavation and construction of the underground structure.

This construction is available since the beams constructed using the composite crossbeam of the present invention may sufficiently endure the soil pressure.

Though it has been illustrated that the mold-concrete composite crossbeam already combined with the buried tube and the lateral reinforcing member is installed to a shape steel and then used for construction, it is also possible that the mold is firstly installed and then the buried tube and the lateral reinforcing member are installed, not limited to the above.

According to the present invention, a connection H-steel20′ for connecting another steel crossbeam to the middle of the mold-concrete composite crossbeam may be further provided as shown inFIG. 25. That is to say, the connection H-steel20′ is adhered to the H-steel20of the composite crossbeam by means of welding or the like to be protruded vertically. A coupling hole20a′ may be formed at the end of the connection H-steel20′ for coupling with another mold-concrete composite crossbeam or H-steel.

FIGS. 26 to 45shows a mold-concrete composite crossbeam according to further other embodiments of the present invention. Here, the same reference numeral as in the former drawings designates the same component.

As shown inFIGS. 26 to 45, various kinds of reinforcing steel bars may be installed to the mold and the concrete member. Hereinafter, each embodiment will be explained with reference to only the sectional view showing the region where the concrete exists.

In the mold-concrete composite crossbeam shown inFIG. 26according to another embodiment of the present invention, the extension steel bar unit33of the stirrup steel bar30is not integrally formed with but separately from the intermediate steel bar unit32, so the extension steel bar unit33is adhered there to by means of welding or the like when the composite crossbeam is made at the construction spot. In case the extension steel bar unit33is prepared separately, the composite crossbeam may be carried or handled more easily.

An extension steel bar unit33aof a stirrup steel bar30aprovided to the mold-concrete composite crossbeam shown inFIG. 27has its front end bent to surround a part of the outer circumference of the exposed steel bar70.

In this case, when the exposed steel bar70is welded or combined to the extension steel bar unit33a, it is possible to ensure more stable coupling force. Furthermore, it is also allowed that the aforementioned auxiliary cap bar36(seeFIG. 10) is not provided.

Referring toFIG. 28, the mold-concrete composite crossbeam according to another embodiment of the present invention is provided with a connection steel bar410extended from the web23of the H-steel20in both side directions.

The connection steel bar410is used for reinforcing the connection with the slab installed on the mold-concrete composite crossbeam. Preferably, the connection steel bar410includes an extension410aextended in both side directions in parallel with the slab from the web23of the H-steel20, and a fixing unit410bextended downward in parallel with the web23and buried in the concrete member40. More preferably, the fixing unit410bmay be fixed to the web23by means of welding or the like.

The connection steel bar410may be installed between the stirrup steel bars30or in contact with the stirrup steel bars30. In case of being contacted with the stirrup steel bar30, the connection steel bar410may be coupled thereto by welding or the like.

In addition, if slab is installed after installing the deck plate400(seeFIG. 16) to the connection steel bar410, the connection steel bar410is buried in the slab to keep coupling with the slab more firmly.

According to another embodiment of the present invention, the connection steel bar may be modified in various ways in order to enhance a coupling force with the concrete member40. That is to say, as shown inFIG. 29, the connection steel bar410′ includes an extension410a′ extended in both side directions from the web23of the H-steel20, and a fixing unit410b′ downwardly extended at a predetermined angle with the web23so that its end is buried in the concrete member40with being coupled to the lower flange22of the H-steel20by welding or the like.

In this case, the fixing unit410b′ of the connection steel bar410′ may further enhance a coupling force with the concrete member40.

Another embodiment to enhance a coupling force with the concrete is shown inFIG. 30. Referring toFIG. 3, the mold-concrete composite crossbeam of this embodiment includes a support50′ provided to the concrete member40, and the support50′ includes a bracket51′ for supporting the deck plate400(seeFIG. 16), and a buried member52′ integrally formed with the bracket51′ and extended to the lower flange22of the H-steel20so as to be buried in the concrete member40.

Here, an end of the buried member52′ is fixed to the lower flange22by means or welding or the like so that the buried member52′ acts as a reinforcing member to enhance a coupling member40with the concrete member40.

FIG. 31showing another embodiment of the present invention illustrates a mold-concrete composite crossbeam that may effectively resist an axial stress together with enhancing a coupling force with the concrete member.

According to this embodiment, a pair of first and second auxiliary steel bars121,122are further installed in the concrete member40in a length direction. The first auxiliary steel bar121is installed to be inscribed to the intermediate steel bar unit32of the stirrup steel bar30, and the second auxiliary steel bar122is installed to be inscribed to the web23of the H-steel20. These auxiliary steel bars also play a role of effectively resisting an axial stress.

In addition, the auxiliary steel bars121,122are interconnected using a coupling steel bar420. The coupling steel bar420is buried in the concrete member40with both ends being coupled or welded to the auxiliary steel bars121,122, respectively.

The coupling steel bars420may be positioned between the stirrup steel bars30at regular intervals, but preferably fixed in contact with the stirrup steel bars30. In this case, the coupling steel bars420configure a closed steel bar shape together with the stirrup steel bars30, thereby playing a role of more effectively resisting a stress applied in an axial direction.

FIG. 32shows an example that the auxiliary steel bars121,122and the coupling steel bars420are provided to the mold-concrete composite crossbeam ofFIG. 30. In this case, the first auxiliary steel bar121is installed to be inscribed to the intermediate steel bar unit32of the stirrup steel bar30, and the second auxiliary steel bar122is installed to be inscribed to the fixing unit110bof the connection steel bar110.

The mold-concrete composite crossbeam shown inFIG. 33according to another embodiment of the present invention is provided with a closed stirrup steel bar180. The closed stirrup steel bar180surrounds the lower flange22of the H-steel20and also its both ends come in contact with both sides of the web23. Both ends of the closed stirrup steel bar180are supported or welded without any separate fixture.

In addition, the upper portion of the closed stirrup steel bar180is not buried in the concrete member40but exposed out, so it is buried in the slab during construction to enhance a mutual coupling force with concrete. In this case, there is no need of providing a separate connection steel bar mentioned above.

In this embodiment, at a portion that requires installation of the exposed steel bar70, an extension member160where the exposed steel bar70is welded or coupled may be installed as shown in the figure.

The extension member160plays the same function as the extension steel bar unit33′ of the embodiment shown inFIG. 26, and it substantially has a L shape. One end of the extension member160is fixed to both edges of the upper portion of the closed stirrup steel bar180by means of welding, and the other end is extended outward in both side directions so that the exposed steel bar70may be fixed thereto.

The extension member160may be installed entire in a length direction or selectively installed as required in a region where the exposed steel bar70is installed.

Referring toFIG. 34showing still another embodiment of the present invention, a support on which a deck plate is positioned and supported is provided on the concrete member40. The support includes bracket51s provided to edges of the upper surface of the concrete member40to support the deck plate, and a connection rod54buried in the concrete member40to interconnect and support the brackets51.

The connection rod54passes through the through hole formed in the web23of the H-steel20so that its one end is fixed to the bracket51at the left and the other end is fixed to the bracket51at the right.

More preferably, the connection rod54may be installed in contact with or adjacent to the Stirrup steel bar30. In this case, the stirrup steel bar30and the connection rod54may further enhance a coupling force with concrete and increase a constraining force of the concrete.

According to further another embodiment of the present invention, as shown inFIG. 35, the mold-concrete composite crossbeam may include a rectangular cover member170that surrounds and protects the concrete member40.

The cover member170is made of synthetic resin including carbon fiber FRP or glass fiber FRP, and the cover member170is installed to surround side and lower sides of the concrete member40.

Preferably, the cover member170may play a role of mold for the region where the concrete member is formed, when the mold-concrete composite crossbeam of the present invention is manufactured. For example, if reinforcing steel bars such as the H-steel20are installed to the cover member170and then concrete is placed and cured, a mold-concrete composite crossbeam integrally coated with the cover member170may be obtained.

In this case, the cover member170may prevent the mold-concrete composite crossbeam from being scratched or damaged during carriage or construction.

According to another embodiment of the present invention, as shown inFIG. 36, a bent corner member170′ may be installed to an edge of the lower end of the concrete member40of the mold-concrete composite crossbeam in a length direction.

In this case, the corner member170′ may be made of steel material or synthetic resin including carbon fiber FRP or glass fiber FRP. More preferably, at least one stud may be provided to the corner member170′ in order to enhance a coupling force between the corner member170′ and the concrete member40.

The mold-concrete composite crossbeam shown inFIGS. 26 to 36have a concrete member with a rectangular section, but it should be understood that the same concept may be applied to a mold-concrete composite crossbeam having a concrete member with a trapezoidal section, though not shown in the figures.

Referring toFIG. 37showing another embodiment of the present invention, the concrete member40′ has a trapezoidal section whose upper surface is wider than the lower surface. In this case, since the upper surface of the concrete member40′ is wider than the lower surface, the area where the deck plate400(seeFIG. 16) is placed is increased.

Now, refer toFIG. 38showing another embodiment of the present invention. The mold-concrete composite crossbeam of this embodiment includes a H-steel20, stirrup steel bars30′ installed at regular intervals to surround the lower portion of the H-steel20, and a concrete member40′ placed to bury at least a part of the H-steel20and having a trapezoidal section.

According to this embodiment, the stirrup steel bar30′ includes a lower steel bar unit31′ extended below the lower flange22of the H-steel across the lower flange22with being buried in the concrete member40′, an intermediate steel bar unit32′ extended with a slant upward and outward from both ends of the lower steel bar unit31′ and having an upper end exposed out of the concrete member, and an extension steel bar unit33′ extended outward in both side directions at the upper end of the intermediate steel bar unit32′.

The intermediate steel bar unit32′ of this embodiment is preferably extended with a slant in parallel with the side of the trapezoidal concrete member40′. Thus, even when the exposed steel bar70is installed out of the extension steel bar unit33′ as well as installed adjacent to the corner, the exposed steel bar70′ does not interfere with a column when a shape steel is connected to the column, as explained later.

Preferably, a support50″ where a deck plate is placed and supported may be further provided to an edge of the upper surface of the concrete member40′ of this embodiment. The support50″ includes a bracket51″ for supporting the deck plate, and a buried member52″ integrally formed with the bracket51″ and buried in the concrete member40.

More preferably, the bracket51″ is a strip member made of metal material with a sectional shape corresponding to the edge of the upper surface of the concrete member40′, for example a L-shaped section. More preferably, the bracket51″ is not protruded out for better appearance, but installed so that the section of the bracket51″ corresponds to the section of the edge of the upper surface of the concrete member40′. Preferably, the outer surface of the bracket51″ configures the same plane as the edge surface of the concrete member40′.

Referring toFIG. 39showing another embodiment of the present invention, the mold-concrete composite crossbeam of this embodiment includes a H-steel20, stirrup steel bars30″ installed at regular intervals to surround a lower portion of the H-steel20, and a concrete member40′ placed to bury at least a part of the H-steel20and having a trapezoidal section.

According to this embodiment, the stirrup steel bar30″ includes a lower steel bar unit31″ extended below the lower flange22of the H-steel20across the lower flange22with being buried in the concrete member40′ an intermediate steel bar unit32″ extended with a slope upward and outward from both ends of the lower steel bar unit31″ and having an upper end exposed out of the concrete member, and an extension steel bar unit33″ extended inward from the upper end of the intermediate steel bar unit32″.

The intermediate steel bar unit32″ of this embodiment is extended in parallel with the side of the trapezoidal concrete member40′. Thus, though the exposed steel bar70″ is installed adjacent to the corner of the extension steel bar unit33″, the exposed steel bar70″ dose not interfere with a column when a shape steel is connected to the column. Accordingly, there is no need of extending the extension steel bar unit33″ outward in a side direction.

FIGS. 40 and 41shows a mold-concrete composite crossbeam according to another embodiment of the present invention. In this embodiment, a hollow40b,40′bpreferably having a rectangular section is formed at the center of the concrete member40a,40′ain a length direction. This hollow40b,40′bmay be formed by installing a metal lath142to a region where the hollow of the concrete40a,40′awill be formed, and then placing concrete thereto. The hollow40b,40′bgives an effect of decreasing the entire weight of the mold-concrete composite crossbeam since concrete is at least partially not filled in the concrete member40a,40′a. Thus, it becomes easier to carry or construct the mold-concrete composite crossbeam of this embodiment.

The size of the hollow40b,40′bmay be suitably adjusted depending on size and weight of the mold-concrete composite crossbeam, and preferably set so that at least a part of the lower flange22of the h-steel20is buried in the concrete member40a,40′a. As an alternative, the lower flange22may be entirely buried in the concrete member40a,40′a. This hollow40b,40′bis formed at least partially, preferably entirely, in a length direction of the concrete member40a,40′a.

Preferably, at least one stud steel bar135,136may be further installed to the concrete member40a,40′aat a region where the hollow40b,40′bexists. The stud steel bar135,136enhances a coupling force with concrete when concrete is put into the hollow40b,40′bfor placing slab therein. More preferably, one end of the stud steel bar135,136is fixed to the stirrup steel bar180,30′, and the other end is extended to the hollow40b,40′b.

As another alternative, as shown inFIG. 42, it is possible to form a shear key51in a concrete side in the hollow instead of the stud steel bar, so as to enhance a coupling force with concrete.

In addition, in order to reduce the weight of the mold-concrete composite crossbeam to the minimum, as shown inFIGS. 43 and 44, a hollow40d,40′dwhose width is gradually increased upward may be formed at the center of the concrete member40c,40′c.

That is to say, the hollow40d,40′dhas a small width at a portion where both ends of the lower flange22of the H-steel20are buried, but the hollow40d,40′dhas an increasing width upward so that the weight of the concrete member40c,40′cmay be reduced to the minimum. Preferably, the hollow40d,40′dis formed to have a trapezoidal sectional shape. When concrete is placed, the concrete is filled in the hollow so that slab and beams are integrally constructed.

Referring toFIG. 45showing another example of the present invention, a filler member190may be provided in the hollow40d(seeFIG. 43) of the concrete member40c. The filler member190plays a roll of filling the hollow, which allows easier construction since there is no need of penetrating concrete into the hollow when the concrete is placed for construction of slab. The filler member190preferably employs Stryofoam, but not limitedly.

FIGS. 46 to 48show a mold-concrete composite crossbeam according to another embodiment of the present invention. Here, the same reference numeral as in the former drawings designates the same component.

Referring toFIGS. 46 to 48, in the mold-concrete composite crossbeam of this embodiment, the concrete member includes a main concrete member440formed with a thickness T2(seeFIG. 48) that exposes the upper flange21of the H-steel20but bury at least a part of the web23and the lower flange22, and a sub concrete member441extended from a lower portion of the end of the main concrete member440and formed with a thickness T1(seeFIG. 47) relatively smaller than the main concrete member440.

The main concrete member440is formed at the center of the mold-concrete composite crossbeam, while the sub concrete member441is formed at both ends. The sub concrete member441may be formed so that its upper surface comes in contact with the lower surface of the lower flange22of the H-steel20, or so that the lower flange22is buried therein.

The sub concrete member441is formed at a portion where the mold will be installed, so the sub concrete member441itself acts as a bottom mold.

According to this embodiment, a mold380composed of a pair of sidewalls382,383is detachably installed to both sides of the sub concrete member441. That is to say, the sidewalls382,383of the mold380are contacted with an end side of the main concrete member440and the side of the sub concrete member441respectively, and the sub concrete member441and the sidewalls382,383form a space where concrete will be placed. At this time, a coupling bolt385passes through the through holes formed in the sidewalls382,383and coupled to a buried nut386buried in the sub concrete member441, thereby fixing the mold.

In addition, referring toFIG. 48showing a connection unit of the main concrete member440and the mold380, a plurality of coupling holes are formed in the mold sidewalls382,383, and a coupling bolt387is inserted therein and coupled to a buried but388buried in the concrete member440. The buried nut388is configured as explained above, and it is buried in advance at a position corresponding to the coupling hole of the sidewall when the concrete member440is formed.

At this time, for more film and stable coupling, auxiliary plates389,390may be additionally provided.

The mold-concrete composite crossbeam of this embodiment is constructed as explained above, so it is not described in detail again.

A mold-concrete composite crossbeam according to another embodiment of the present invention is shown inFIGS. 49 and 50.

Referring toFIGS. 49 and 50, in the composite crossbeam of this embodiment, the mold is separately configured with a fixed mold part510and a detachable mold part520. The fixed mold part510is connected to a column at both ends of the mold-concrete composite crossbeam and used as a permanent structure buried or fixed in the placed concrete, while the detachable mold part520is dismantled after the concrete is cured, and then utilized again.

The fixed mold part510and the detachable mold part520are interconnected using a plurality of connectors530,540,550. That is to say, bottoms of the mold parts510,520are interconnected using the connector530, and sidewalls of the mold parts510,520are interconnected using the connectors540,550. At this time, connection bolts511,512,521,522,531,532pass through the through holes formed in the connectors530,540,550and the coupling holes formed in the fixed and detachable mold parts510,520and respectively coupled to buried nuts513,514,523,524,533,534.

The mold-concrete composite crossbeam of this embodiment is constructed in the same way as explained above. In addition, in order to separate the detachable mold part520after concrete is cured, the connection bolts511,512,521,522,531,532are released to remove the connectors530,540,550, and then the detachable mold part520is detached. At this time, the fixed mold part510remains as a permanent structure together with concrete, and the buried nuts513,514,523,524,533,534also remain buried in the concrete.

The fixed mold part and the detachable mold part may be connected with ach other in various ways, as shown inFIGS. 51 and 52as an example. Components other than the mold parts are not illustrated inFIGS. 51 and 52for simplification.

Referring toFIGS. 51 and 52, the fixed mold part510and the detachable mold part520are interconnected using connectors610and620,630and640,650and660having a L-shaped section. One pair of connectors610,620include coupling units610a,620acoupled to the bottoms of the mold parts510,520, and extensions610b,620bextended in a perpendicular direction from the coupling units610a,620aand coupled with each other in contact.

In addition, one pair of connectors630,640include coupling units630a,640acoupled to one sidewalls of the mold parts510,520respectively, and extensions630b,640bextended in a perpendicular direction from the coupling units630a,640aand coupled with each other in contact.

In addition, one pair of connectors650,660include coupling units650a,660acoupled to the other sidewalls of the mold parts510,520, and extensions650b,660bextended in a perpendicular direction from the coupling units650a,660aand coupled with each other in contact.

The coupling units610a,620a,630a,640a,650a,660aare respectively fixed using connection bolts621,622,641,642,661,662and buried nuts623,624,643,644,663,664, and the extensions610b,620b,630b,640b,650b,660bare coupled with each other using coupling bolts611,631,651and coupling nuts612,632,652.

The composite mold of this embodiment is constructed in the same way as explained above. Also, in order to dismantle the mold after concrete is molded, the connection bolt and the coupling bolts are released to remove the connectors, and then the detachable mold part520may be separated.

INDUSTRIAL APPLICABILITY

As described above, the mold-concrete composite crossbeam according to the present invention gives the following effects.

First, the mold-concrete composite crossbeam of the present invention may effectively reduce the height of story without giving any influence on the safety of structure.

Second, the mold-concrete composite crossbeam of the present invention may allow effective resistance against the bending stress and compression stress applied to a structure.

Third, the mold-concrete composite crossbeam of the present invention does not need any separate fire-resistant coating on the H-steel.

Fourth, the mold-concrete composite crossbeam of the present invention has the exposed steel bar inclined relatively toward outside from its center so that the exposed steel bar passes aside a column during construction, so there is no need of cutting or finishing the exposed steel bar or welding the exposed steel bar to the column.

Fifth, the mold-concrete composite crossbeam of the present invention is already provide with a mold, so there is no need of additionally installing a mold. Thus, the present invention allows easier construction, and the mold may be easily separated and recycled after concrete is cured.

Sixth, the mold-concrete composite crossbeam of the present invention may adjust the length of the concrete member as required, and may also significantly reduce the entire weight of the concrete composite shape steel by forming a hollow in at least a part of the concrete member, so it may be easily carried and constructed.

Seventh, according to the present invention, it is not required to construct a stud that is installed for connection between existing frame beams and slabs.

Eighth, the mold-concrete composite crossbeam of the present invention may be very easily installed and constructed, and the composite crossbeam is constructed to be suspended, thereby ensuring a working space below it and also facilitating the following process.

Ninth, the construction method using the mold-concrete composite crossbeam according to the present invention allows a short term of works and reduced construction costs since underground stories are preliminarily constructed with placing only beams or a part of slab and beams without installing the entire slab, and then the main construction is progressed together with constructing stories over the ground.