US20190376283A1 - Steel form - Google Patents
Steel form Download PDFInfo
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- US20190376283A1 US20190376283A1 US16/549,310 US201916549310A US2019376283A1 US 20190376283 A1 US20190376283 A1 US 20190376283A1 US 201916549310 A US201916549310 A US 201916549310A US 2019376283 A1 US2019376283 A1 US 2019376283A1
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- Prior art keywords
- steel
- steel form
- girder
- binding beam
- pair
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Classifications
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/16—Structures made from masses, e.g. of concrete, cast or similarly formed in situ with or without making use of additional elements, such as permanent forms, substructures to be coated with load-bearing material
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B5/00—Floors; Floor construction with regard to insulation; Connections specially adapted therefor
- E04B5/02—Load-carrying floor structures formed substantially of prefabricated units
- E04B5/04—Load-carrying floor structures formed substantially of prefabricated units with beams or slabs of concrete or other stone-like material, e.g. asbestos cement
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/16—Structures made from masses, e.g. of concrete, cast or similarly formed in situ with or without making use of additional elements, such as permanent forms, substructures to be coated with load-bearing material
- E04B1/167—Structures made from masses, e.g. of concrete, cast or similarly formed in situ with or without making use of additional elements, such as permanent forms, substructures to be coated with load-bearing material with permanent forms made of particular materials, e.g. layered products
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B5/00—Floors; Floor construction with regard to insulation; Connections specially adapted therefor
- E04B5/16—Load-carrying floor structures wholly or partly cast or similarly formed in situ
- E04B5/32—Floor structures wholly cast in situ with or without form units or reinforcements
- E04B5/36—Floor structures wholly cast in situ with or without form units or reinforcements with form units as part of the floor
- E04B5/38—Floor structures wholly cast in situ with or without form units or reinforcements with form units as part of the floor with slab-shaped form units acting simultaneously as reinforcement; Form slabs with reinforcements extending laterally outside the element
- E04B5/40—Floor structures wholly cast in situ with or without form units or reinforcements with form units as part of the floor with slab-shaped form units acting simultaneously as reinforcement; Form slabs with reinforcements extending laterally outside the element with metal form-slabs
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
- E04C3/29—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces built-up from parts of different material, i.e. composite structures
- E04C3/293—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces built-up from parts of different material, i.e. composite structures the materials being steel and concrete
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B5/00—Floors; Floor construction with regard to insulation; Connections specially adapted therefor
- E04B5/02—Load-carrying floor structures formed substantially of prefabricated units
- E04B5/10—Load-carrying floor structures formed substantially of prefabricated units with metal beams or girders, e.g. with steel lattice girders
Definitions
- the present invention relates to a steel form.
- Patent Document 1 Proposed in the related art is a method for using a grooved steel form (approximately U-shaped in cross section) matching the outer shell shape of a beam as a beam form for labor-saving form construction for example, Patent Document 1).
- Patent Document 1 Japanese Unexamined Patent Application Publication No. Heisei 10-140654
- Patent Document 1 The steel form described in Patent Document 1 needs to be formed by processing a thin steel plate into a shape matching the outer shell shape of a beam by, for example, roll molding or press molding. As a result, it takes labor and cost to process the steel form. Besides, the grooved steel form is bulky in terms of transport, and thus the number of the grooved steel forms that can be transported at one time is limited. As a result, it takes labor and cost to transport the steel form.
- a steel form which is a steel form for steel-framed concrete beam formation, includes a pair of frame members, wherein each of the pair of frame members is provided with a bottom plate portion and a side plate portion extending upward from the bottom plate portion, the bottom plate portion has a joining surface for joining the respective bottom plate portions of the pair of frame members to each other, and a groove portion allowing concrete placement is formed by the respective bottom and side plate portions of the pair of frame members.
- FIGS. 1( a ) and 1( b ) are a set of views illustrating a steel-framed concrete beam (binding beam) according to Embodiment 1 of the invention, in which FIG. 1( a ) is a left side view and FIG. 1( b ) is a cross-sectional view taken along arrow A-A in FIG. 1( a ) .
- FIG. 2 is an exploded perspective view illustrating a temporary state during construction in the vicinity of the joining portion between the binding beam and a girder.
- FIG. 3 is a view illustrating the relationship between a cross section of the binding beam and calculation parameters.
- FIG. 4 is a graph showing the relationship between a slab thickness and a long-term bending rigidity ratio.
- FIG. 5 is a graph showing the relationship between the slab thickness and a short-term bending rigidity ratio.
- FIG. 6 is a graph showing the relationship between the load that is applied to the binding beam and the shear rigidity ratio of a steel form, which pertains to a case where no web opening is present.
- FIG. 7 is a graph showing the relationship between the load that is applied to the binding beam and the shear rigidity ratio of the steel form, which pertains to a case where a web opening is present.
- FIGS. 8( a )-8( c ) are a set of cross-sectional perspective views corresponding to the A-A arrow cross section in FIG. 1( a ) , in which FIG. 8( a ) illustrates the binding beam at the completion of a steel form installation step, FIG. 8( b ) illustrates the binding beam at the completion of main bar arrangement, deck plate installation, and placement steps, and FIG. 8( c ) illustrates the binding beam at the completion of a penetration step.
- FIGS. 9( a )-9( c ) are a set of cross-sectional perspective views corresponding to the A-A arrow cross section in FIG. 1( a ) , in which FIG. 9( a ) illustrates the binding beam at the completion of steel form installation and cylindrical form installation steps, FIG. 9( b ) illustrates the binding beam at the completion of main bar arrangement, deck plate installation, and placement steps, and FIG. 9( c ) illustrates the binding beam at the completion of a penetration step.
- FIGS. 10( a ) and 10( b ) are a set of views illustrating a state where a Z-steel is transported, in which FIG. 10( a ) is an end view illustrating the state of transport of a Z-steel of Embodiment 1 and FIG. 10( b ) is an end view illustrating the state of transport of a Z-steel according to a first modification example.
- FIGS. 11( a ) and 11( b ) are a set of views illustrating a steel form according to a second modification example, in which FIG. 11( a ) is a plan view of the steel form that is yet to be bent and FIG. 11( b ) is a side view of the steel form that is bent.
- FIGS. 12( a ) and 12( b ) are a set of views illustrating the vicinity of the joining portion between a binding beam and a girder according to a third modification example, in which FIG. 12( a ) is a left side view and FIG. 12( b ) is a cross-sectional view taken along arrow B-B in FIG. 12( a ) .
- FIGS. 13( a ) and 13( b ) are a set of views illustrating the vicinity of the joining on between a binding beam and a girder according to a fourth modification example, in which FIG. 13( a ) is a right side view and FIG. 13( b ) is a plan view.
- FIG. 14 is a right side view illustrating the vicinity of the joining portion between a binding beam and a girder according to a fifth modification example.
- FIG. 15 is a right side view illustrating the vicinity of the joining portion between a binding beam and a girder according to a sixth modification example.
- FIG. 16 is a perspective view of an end portion of the steel form of the binding beam in FIG. 15 .
- FIG. 17 is a right side view illustrating the vicinity of the joining portion between a binding beam and a girder according to a seventh modification example.
- FIG. 18 is a side view illustrating the vicinity of the joining portion between a binding beam and a girder according to an eighth modification example.
- FIG. 19 is a plan view of FIG. 18 .
- FIG. 20 is a cross-sectional view corresponding to the A-A arrow cross section in FIG. 1( a ) and is a cross-sectional view of a steel form of a binding beam according to a ninth modification example.
- FIG. 21 is a cross-sectional view corresponding to the A-A arrow cross section in FIG. 1( a ) and is a cross-sectional view of a steel form of a binding beam according a tenth modification example.
- FIGS. 22( a ) and 22( b ) are a set of cross-sectional views corresponding to the A-A arrow cross section in FIG. 1( a ) , in which FIG. 22( a ) illustrates a steel form of a binding beam according to an eleventh modification example and FIG. 22( b ) illustrates a steel form of a binding beam according to a twelfth modification example.
- FIGS. 23( a ) and 23( b ) are a set of cross-sectional views corresponding to the A-A arrow cross section in FIG. 1( a ) , in which FIG. 23( a ) illustrates a steel form of a binding beam according to a thirteenth modification example and FIG. 3( b ) illustrates a steel form of a binding beam according to a fourteenth modification example.
- the embodiments relate to a steel form.
- the “steel form” is a form provided with steel for forming steel-framed concrete beams constituting building.
- the “steel-framed concrete beam” is a beam provided with at least a steel frame and concrete.
- the steel-framed concrete beam may be provided with a component other than the steel frame and the concrete.
- the embodiments illustrate an example in which the steel-framed concrete beam is configured as a steel-framed reinforced concrete beam that has a rebar in addition to a steel frame and concrete.
- the steel-framed reinforced concrete beam may be provided with, for example, a main bar and a stirrup as the rebar, a case where the steel-framed reinforced concrete beam is provided with a main bar and no stirrup will be described below.
- the steel-framed concrete beam may be provided with, for example, a stirrup and no main bar, both a main bar and a stirrup, or no main bar and no stirrup.
- the steel frame is capable of having any shape insofar as the steel frame functions as a form allowing concrete placement.
- a case where the steel frame has an axial cross section in a hat shape (a shape obtained by joining a pair of Z-steels to each other) will be described below.
- the steel-framed concrete beam according to the embodiments is applicable to any installation floor. Although a case where the steel-framed concrete beam is a second floor beam will be described below, the steel-framed concrete beam is applicable to beams of other floors as well. Although a case where the steel-framed concrete beam is a binding beam will be described below, the steel-framed concrete beam may be a girder as well.
- FIG. 1 is a set of views illustrating the steel-framed concrete beam according to Embodiment 1 (hereinafter, simply referred to as “binding beam” 1 ).
- FIG. 1( a ) is a left side view and FIG. 1( b ) is a cross-sectional view taken along arrow A-A in FIG. 1 ( a ).
- the binding beam 1 according to Embodiment 1 is provided with a steel form 10 , binding beam concrete 20 , main bars 30 , and web openings (through holes) 40 .
- the +X-X direction in each drawing will be referred to as “width direction” as necessary.
- the +X direction will be referred to as “rightward direction” and the ⁇ X direction will be referred to as “leftward direction”.
- the +Y-Y direction will be referred to as “depth direction” or “forward-rearward direction”.
- the +Y direction will be referred to as “forward direction” and the ⁇ Y direction will be referred to as “rearward direction”.
- the +Z-Z direction will be referred to as “height direction” or “upward-downward direction”.
- the +Z direction will be referred to as “upward direction” and the ⁇ Z direction will be referred to as “downward direction”.
- the direction toward the plane along the width direction (+X-X) will be referred to as “inward direction” and the direction away from the plane along the width direction (+X-X) will be referred to as “outward direction”.
- the steel form 10 is a steel form that has a groove portion (described later) for placing the binding beam concrete 20 .
- This steel form 10 is provided in each binding beam 1 constituting a building and is disposed so as to cover the binding beam 1 from below.
- the steel form 10 of Embodiment 1 is formed by a pair of (that is, two) Z-steels 11 being mutually joined in bottom plate portions 12 (described later) at a construction site.
- the invention is not limited thereto, and the steel form 10 may be integrally formed with a single member or may be formed by three or more members being combined.
- the integrally formed members (the bottom plate portion 12 , a side plate portion 13 , a flange portion 14 , and a reinforcing portion 15 to be described later) that constitute the Z-steel 11 may be formed separately.
- Each of the pair of Z-steels 11 can be substantially similar in configuration to the other, and thus only one of the Z-steels 11 will be described below.
- the Z-steel 11 that is positioned on the right of the binding beam 1 (in the +X direction) will be referred to as “right Z-steel” and the Z-steel 11 that is positioned on the left of the binding beam 1 (in the ⁇ X direction) will be referred to as “left Z-steel”.
- right Z-steel the Z-steel 11 that is positioned on the right of the binding beam 1 (in the +X direction)
- the Z-steel 11 that is positioned on the left of the binding beam 1 (in the ⁇ X direction) will be referred to as “left Z-steel”.
- a specific method for forming the steel form 10 will be described later.
- the Z-steel 11 is a frame member that constitutes the steel form 10 . As illustrated in FIG. 1( b ) , the Z-steel 11 is a steel material that has a substantially Z-shaped axial cross section. The Z-steel 11 is provided with the bottom plate portion 12 , the side plate portion 13 , the flange portion 14 , and the reinforcing portion 15 .
- the bottom plate portion 12 is a steel plate positioned on the bottom surface of the steel form 10 .
- the bottom plate portion 12 has a joining surface 16 for mutually joining the respective bottom plate portions 12 of the pair of Z-steels 11 .
- the pair of Z-steels 11 are joined to each other on the joining surface 16 .
- a part of the bottom plate portion 12 of the right Z-steel is superposed on a part of the bottom plate portion 12 of the left Z-steel and each of the parts where the pair of Z-steels 11 are in contact with each other (the upper surface of the bottom plate portion 12 of the left Z-steel and the lower surface of the bottom plate portion 12 of the right Z-steel) is the joining surface 16 .
- the joining on the joining surface 16 can be performed by any specific method.
- a plurality of bolt holes (not illustrated) are spaced apart along the longitudinal direction (+Y-Y direction) of the beam in the joining surfaces 16 of both Z-steels 11 and both Z-steels 11 are joined by bolt fastening by means of the bolt holes.
- Specific joining methods are not limited thereto. For example, welding-based joining and screw penetration-based joining may be performed instead.
- the side plate portion 13 is a steel plate extending in the upward direction from the bottom plate portion 12 .
- the side plate portion 13 is a part that is folded back from the outer end of the bottom plate portion 12 and extends to the upper end of the beam and is positioned so as to cover the left and right sides of the binding beam 1 .
- the length of the side plate portion 13 in the height direction (+Z-Z direction) is longer, by the thickness of the bottom plate portion 12 , in the left Z-steel than in the right Z-steel. This is for the upper end positions of the side plate portions 13 of both Z-steels 11 (that is, the height positions of the flange portions 14 ) to coincide with each other when the pair of Z-steels 11 are overlapped.
- the part that is formed by the side plate portions 13 and the bottom plate portions 12 of a pair of the steel forms 10 and has a U-shaped axial cross section will be referred to as groove portion as necessary.
- Concrete can be placed in the groove portion by the steel form 10 forming the groove portion as described above.
- the lower and side parts of the binding beam 1 are covered with a steel plate by the groove portion, and thus it is possible to deter steam from escaping from the lower and side parts of the binding beam concrete 20 during a fire, it is possible to deter a temperature rise in the room below the binding beam 1 , and it is possible to improve the fire resistance performance of the binding beam 1 .
- the flange portion 14 is a steel plate extending in the outward direction from the upper end of the side plate portion 13 . Specifically, the flange portion 14 is a part that is folded back in the outward direction from the upper end of the side plate portion 13 and extends along a horizontal plane, and a deck plate 3 is placed and screwed on the flange portion 14 . Although a case where this deck plate 3 is a known corrugated steel plate will be described, the invention is not limited thereto and a flat plate may be used as the deck plate 3 .
- the binding beams 1 are arranged side by side at intervals along the longitudinal direction of a girder 2 , one end portion of the deck plate 3 is placed in the flange portion 14 of one binding beam 1 as illustrated in FIG. 1( b ) , and the other end portion of the deck plate 3 is similarly placed in the flange portion 14 of the binding beam 1 that is adjacent to the one binding beam 1 .
- the flange portion 14 being provided as described above, the load of slab concrete 4 (described later) can be received by the flange portion 14 and is allowed to smoothly flow to the binding beam 1 and the proof stress of the binding beam 1 is improved.
- the reinforcing portion 15 is a steel plate extending in the downward direction from the outer end of the flange portion 14 .
- the reinforcing portion 15 being provided as described above and thickness being given to the outer end of the flange portion 14 , the local buckling of the outer end of the flange portion 14 that pertains to a case where the slab concrete 4 is placed and the flange portion 14 receives the load of the slab can be deterred.
- the reinforcing portion 15 of Embodiment 1 extends in the downward direction from the outer end of the flange portion 14 .
- the invention is not limited thereto and the reinforcing portion 15 may extend in, for example, the upward direction.
- the binding beam concrete 20 is concrete placed in the groove portion that the pair of side plate portions 13 and the bottom plate portion 12 of the steel form 10 constitute.
- the binding beam concrete 20 is known concrete solidified after filling in the groove portion, and the plurality of web openings 40 are formed in the binding beam concrete 20 as described above.
- the slab concrete 4 for forming an upper floor slab is formed along a horizontal plane above the binding beam concrete 20 .
- Girder concrete (reference numeral omitted) for forming the girder 2 is formed, so as to be orthogonal to the binding beam 1 , at the front and rear ends of the binding beam concrete 20 .
- the binding beam concrete 20 , the slab concrete 4 , and the girder concrete are given different names and reference numerals, the binding beam concrete 20 , the slab concrete 4 , and the girder concrete are simultaneously placed and formed in Embodiment 1.
- the binding beam concrete 20 , the slab concrete 4 , and the girder concrete will be simply referred to as “concrete” when no distinguishment among them is necessary.
- the main bars 30 are rebars extending along the axial center direction of the beam. Although two upper end bars and four lower end bars are illustrated as an example in Embodiment 1, the number and disposition of the main bars 30 are not limited thereto.
- the web opening 40 is a hole formed so as to penetrate the side plate portion 13 and the binding beam concrete 20 .
- the web opening 40 is formed by, for example, the side plate portion 13 and the binding beam concrete 20 being drilled with a drill after the binding beam concrete 20 placed in the steel form 10 is solidified.
- the web opening 40 being formed as described above, a duct or piping for air conditioning, electrical equipment, and so on can be passed through the web opening 40 (a case where a duct for air conditioning is passed through the web opening 40 will be described below Accordingly, the duct can be extended from one of spaces sandwiching the beam 1 (such as the space to the right of the binding beam 1 ) to the other thereof (such as the space to the left of the binding beam 1 ) and the degree of freedom of duct disposition is improved.
- the web opening 40 is formed in the web opening forming portion of the binding beam 1 .
- the “web opening forming portion” is a part where the web opening 40 penetrating the side plate portion 13 and the binding beam concrete 20 can be formed.
- the “web opening forming portion” is a part where no rebar (main bar 30 in Embodiment 1) is arranged (part where the drill does not interfere with the rebar when the web opening 40 is drilled with the drill).
- the “web opening forming portion” is a part above the lower main bar 30 (lower end bar) in the binding beam 1 .
- the number of the web openings 40 is six and the web openings 40 are along the axial center direction of the beam in the illustration. The number of the web openings 40 is not limited to six.
- FIG. 2 is an exploded perspective view illustrating a temporary state during construction in the vicinity of the joining portion between the binding beam 1 and the girder 2 .
- the concrete and the rebar that constitute the binding beam 1 and the girder 2 are not illustrated in FIG. 2 for convenience of illustration.
- a notch hereinafter, referred to as binding beam accommodating portion 2 b
- binding beam accommodating portion 2 b having a shape (hat shape) substantially corresponding to the axial cross-sectional shape of the binding beam 1 is formed in a side surface of a wooden form 2 a of the girder 2 according to Embodiment 1.
- the binding beam 1 and the girder 2 can be formed at the same time by concrete being simultaneously placed in the wooden form 2 a of the girder 2 and the steel form 10 with the steel form 10 of the binding beam 1 fitted in the binding beam accommodating portion 2 b.
- notches hereinafter, referred to as flange accommodating portions 2 c ) having the same width as the flange portion 14 are formed on the left and right of the upper end of the binding beam accommodating portion 2 b.
- the flange portion 14 can be housed in the flange accommodating portion 2 c.
- a gap equivalent to the height of the reinforcing portion 15 is formed below the flange portion 14 .
- a sealing material 2 d illustrated rectangular wood or the like filling this gap is disposed for prevention of concrete leakage from the gap.
- Temporary supports may support the binding beam 1 until concrete placement.
- the positions and number of the temporary supports may be appropriately changed in accordance with the length and weight of the binding beam 1 .
- one temporary support may be provided in one axial end portion, one temporary support may be provided in the other axial end portion, and one temporary support may be provided in the axial middle portion.
- the steel form 10 is higher in proof stress than the wooden form 2 a, and thus the temporary supports may be omitted if the temporary supports are unnecessary in view of the length and weight of the binding beam 1 .
- the allowable bending moment or the allowable shear force of the binding beam 1 is calculated by the following Equation (1).
- F RC allowable bending moment or allowable shear force of binding beam concrete 20 (hereinafter, referred to as reinforced concrete (“RC”) as necessary)
- ⁇ burden factor of allowable bending moment or allowable shear force of steel form 10 , which is 0.5 or less
- the allowable bending moment design method will be described first.
- the allowable bending moment is designed after division into a long-term allowable bending moment and a short-term allowable bending moment.
- the long-term allowable bending moment is calculated by the following Equation (2).
- the short-term allowable bending moment is calculated by the following Equation (3).
- FIG. 3 is a view illustrating the relationship between the cross section of the binding beam 1 and calculation parameters.
- L M RC long-term allowable bending moment of RC cross section part (which may be a t ⁇ L f t ⁇ j in case where tensile rebar ratio of RC cross section is balanced rebar ratio or less)
- M uRC ultimate bending strength of RC cross section part
- the long-term allowable bending moment is an allowable bending moment over a relatively long time (such as several years to several decades).
- the short-term allowable bending moment is an allowable bending moment over a relatively short time (such as several hours to several days).
- the allowable bending moment is calculated after the division into the two periods as described above so that an allowable bending moment suitable for each load bearing ratio is designed in view of the fact that the load bearing ratio of the RC and the steel form 10 in the binding beam 1 can vary as the situation of loading on the binding beam 1 can vary with the lengths of the periods.
- the loading on the binding beam 1 is relatively small in a relatively long time, and thus it is assumed that the RC of the binding beam 1 is maintained without breaking (see the lower left cross section in FIG. 4 (described later)) and the load bearing ratio of the RC increases.
- the loading on the binding beam 1 is relatively large (for example, the loading becomes relatively large by a forklift that carries a heavy object passing through the binding beam 1 ), and thus it is assumed that the load bearing ratio of the RC decreases as a result of cracking at the lower end of the RC of the binding beam 1 (see the lower left cross section in FIG.
- the load bearing ratio of the RC and the steel form 10 in the binding beam 1 is expressed in Equations 2 and 3 as a steel frame bending burden effective factor ⁇ M , and then this steel frame bending burden effective factor ⁇ M is given different values in the long-term and short-term cases and the allowable bending moment suitable for each load bearing ratio is designed as a result.
- the bending rigidity ratio ⁇ M can vary with the plate thickness of the steel form 10 and the thickness of the slab concrete 4 attached to the binding beam 1 (hereinafter, referred to as “slab” as necessary), and thus an application restriction range is set for each of the plate thickness of the steel form 10 and the thickness of the slab, the bending rigidity ratio ⁇ M is calculated on the premise of the application restriction range, and the steel frame burden effective factor ⁇ M is determined from the calculated bending rigidity ratio ⁇ M .
- the plate thickness of the steel form 10 has an application restriction range of 3.2 mm or more.
- the load bearing ratio of the steel form 10 increases as the plate thickness of the steel form 10 increases, and thus a lower limit value of “3.2 mm” and application restriction range setting “at or above” the lower limit value allow the steel frame burden effective factor ⁇ M to remain above it insofar as the plate thickness of the steel form 10 is determined in the application restriction range.
- the thickness of the slab has an application restriction range of 200 mm or less.
- the ratio of load bearing by the slab increases as the thickness of the slab increases, and then the load bearing ratio of the steel form 10 decreases. Accordingly, an upper limit value of “200 mm” and application restriction range setting “at or below” the upper limit value allow the steel frame burden effective factor ⁇ m to remain above it insofar as the thickness of the slab is determined in the application restriction range.
- FIG. 4 is a graph showing the relationship between the thickness of the slab and a long-term bending rigidity ratio L ⁇ M
- FIG. 5 is a graph showing the relationship between the thickness of the slab and a short-term bending rigidity ratio S ⁇ M
- the horizontal axis represents the thickness of the slab
- the vertical axis represents the bending rigidity ratio ⁇ M (long-term bending rigidity ratio L ⁇ M or short-term bending rigidity ratio S ⁇ M )
- the solid line indicates a load of 3.2 tons
- the dotted line indicates a load of 4.5 tons.
- the cross-sectional shape of the binding beam 1 is a standard cross section (6.5 in in total length, 300 mm in total width, and 550 mm in total height).
- the long-term bending rigidity ratio L ⁇ M is approximately 0.12 at 200 mm, which is the upper limit value of the application restriction range of the slab thickness, and thus the long-term bending rigidity ratio L ⁇ M was set to 0.1 in view of safety.
- FIG. 4 in the long term, the long-term bending rigidity ratio L ⁇ M is approximately 0.12 at 200 mm, which is the upper limit value of the application restriction range of the slab thickness, and thus the long-term bending rigidity ratio L ⁇ M was set to 0.1 in view of safety.
- M RC /M S is the allowable proof stress ratio between the RC cross section and the steel form 10 and M RC /M S is 1.35 in a case where the bar arrangement of the RC cross section is 4-HD13 (four deformed rebars (steel deformed bars) having a yield point of 345 N/mm2 or more) and the plate thickness of the steel form 10 is 3.2 mm in the cross sections in FIGS. 4 and 5 .
- a simplified method ( ⁇ method) is used in which the restriction of the application restriction range is applied to the plate thickness of the steel form 10 and the thickness of the slab.
- the design formula is determined on the safety side so that the design formula does not become complicated (low iron burden rate being set in terms of design).
- the cross section part of the steel form 10 is restrained by the RC cross section part and the steel form 10 undergoes no lateral buckling as a thin plate, and thus a tensile stress f t is adopted as an allowable stress f b of the steel material of the steel form 10 .
- the allowable shear force design method is designed after division into a long-term allowable shear force and a short-term allowable shear force similarly to the above idea related to the allowable bending moment.
- the long-term allowable shear force is calculated by the following Equation (5) and the short-term allowable shear force is calculated by the following Equation (6).
- the relationship between the cross section of the binding beam 1 and calculation parameters is as illustrated in FIG. 3 .
- the shear effective cross-sectional area Ac of the RC portion used in the shear force calculation is the same cross section as the binding beam 1 used in the experiment as illustrated in FIG. 3 and the cross-sectional area of the slab on the flange portion of the steel form 10 may also be included.
- the steel frame shear burden effective factor ⁇ Q in the shear force calculation formula can be obtained from a shear rigidity ratio ⁇ Q of the steel form 10 indicated by the result of the inventor's experiment.
- FIG. 6 is a graph showing the relationship between the load that is applied to the binding beam 1 and the shear rigidity ratio ⁇ Q of the steel form 10 , which pertains to a case where the web opening (opening) 40 is absent.
- FIG. 7 is a graph showing the relationship between the load that is applied to the binding beam 1 and the shear rigidity ratio ⁇ Q of the steel form 10 , which pertains to a case where the web opening (opening) 40 is present.
- the horizontal axis represents the applied load and the vertical axis represents the shear rigidity ratio ⁇ Q .
- the shear rigidity ratio ⁇ Q of the steel form 10 is substantially constant at approximately 0.2 regardless of the presence or absence of the web opening 40 and the magnitude of the applied load. Accordingly, in the present embodiment, the steel frame shear burden effective factor ⁇ Q was obtained with shear rigidity ratio ⁇ Q set to 0.2.
- Q RC /Q S is the ratio between the shear capacity of the steel form 10 and the RC cross section.
- Q RC /Q S is 1.04 in a case where the cross-sectional shape of the binding beam 1 is a standard cross section (6.5 m in total length, 300 mm in total width, and 550 mm in total height) and the thickness of the steel form 10 is 3.2 mm.
- the long-term steel frame bending burden effective factor L ⁇ M is 0.1 and the short-term steel frame bending burden effective factor S ⁇ M is 0.4 in the design of the allowable bending moment.
- the steel frame shear burden effective factor ⁇ Q is 0.2.
- the burden factor ⁇ of the steel form 10 may be another value, the upper limit of the load bearing ratio of the steel form 10 is set to 50% and the burden factor ⁇ of the steel form 10 is set to 0.5 or less for safety enhancement.
- the lower limit of the load bearing ratio of the steel form 10 can be at least 10% in view of the graphs in FIGS. 6 and 7 and the burden factor ⁇ of the steel form 10 can be set to 0.1 or more.
- the steel form 10 may be used only as a form of the binding beam concrete 20 and the steel form 10 may be allowed to bear no load.
- the burden factor ⁇ of the steel form 10 may be 0.
- the Z-steel 11 is manufactured at a factory.
- the Z-steel 11 can be manufactured by any specific method.
- the Z-steel 11 can be formed by bending of one flat thin steel plate.
- the manufactured Z-steel 11 is transported to a construction site.
- a plurality of the Z-steels 11 can be transported in an overlapping manner, and thus it is possible to transport more Z-steels 11 at one time than in the case of transporting the pair of mutually joined Z-steels 11 .
- Transport efficiency enhancement can be achieved as a result.
- the sealing material (small piece) 2 d described with reference to FIG. 2 may be attached to the lower part of the flange portion 14 by any method such as adhesion before the transport.
- the strength of the flange portion 14 or the reinforcing portion 15 can be enhanced by the sealing material 2 d and deformation of the flange portion 14 or the reinforcing portion 15 attributable to a load or an impact during the transport can be prevented.
- a reinforcing material (not illustrated) similar in shape to the sealing material 2 d may be provided at a predetermined interval below the flange portion 14 or a long reinforcing material (not illustrated) resulting from extension of the sealing material 2 d in the Y direction in FIG.
- Such reinforcing materials may be removed after the transport or may be permanently fixed without removal.
- the strength of the flange portion 14 or the reinforcing portion 15 can be reduced to the same extent in a case where the strength of the flange portion 14 or the reinforcing portion 1 . 5 can be improved by such a reinforcing material being provided, and thus the flange portion 14 and the reinforcing portion 15 may be reduced in thickness or the dimension at which the reinforcing portion 15 extends from the flange portion 14 may be shortened.
- the pair of Z-steels 11 transported to the construction site are joined together and the steel form 10 is formed.
- the bottom plate portions 12 of the right Z-steel and the left Z-steel are overlapped and, in that state, a bolt may be inserted through and fastened in each of bolt holes illustrated) formed at an appropriate interval at the overlapping part of both bottom plate portions 12 .
- a member for maintaining a constant interval between the respective side plate portions 13 of the Z-steels 11 For example, a batten positioned in the groove portion and fixing the interval by propping the side plate portions 13 or a U-shaped veneer board fitted to the outer edge shape of the groove portion may be temporarily installed and removed after both Z-steels 11 are joined to each other.
- FIG. 8 is a set of cross-sectional perspective views corresponding to the A-A arrow cross section in FIG. 1( a ) .
- FIG. 8( a ) illustrates the binding beam 1 at the completion of a steel form installation step.
- FIG. 8( b ) illustrates the binding beam 1 at the completion of main bar arrangement, deck plate installation, and placement steps
- FIG. 8( c ) illustrates the binding beam 1 at the completion of a penetration step.
- the steel form installation step is performed as illustrated in FIG. 8( a ) .
- the steel form 10 formed by the above-described forming method is lifted by a heavy machine or the like and installed at a beam construction position.
- the installation is performed such that an end portion of the steel form 10 is connected to the wooden form 2 a of the girder 2 as illustrated in FIG. 2 .
- the steel form 10 of the binding beam 1 in FIG. 2 is illustrated as being tightly fit in the notch (binding beam accommodating portion 2 b ) of the wooden form 2 a of the girder 2 .
- the invention is not limited thereto.
- the binding beam accommodating portion 2 b may be enlarged in the width direction so that insertion of the steel form 10 into the binding beam accommodating portion 2 b is facilitated and the space between the steel form 10 and the binding beam accommodating portion 2 b may be filled with wood or the like after the insertion of the steel form 10 .
- the steel form 10 is supported by means of a temporary support so as to be capable of enduring the subsequent concrete placement.
- the main bars 30 are arranged in the steel form 10 in the main bar arrangement step. Specifically, the main bars 30 are assembled, lifted by means of a heavy machine or the like, and dropped into and disposed in the groove portion. Likewise, the main bars 30 (not illustrated) of the girder 2 are dropped into and disposed in the wooden form 2 a of the girder 2 . Then, the main bars 30 of the binding beam 1 are bent in, for example, end portions and fixed to the main bars 30 of the girder 2 .
- the deck plates 3 are installed on the flange portions 14 of the steel form 10 in the deck plate installation step.
- the plurality of deck plates 3 are placed on the flange portions 14 so as to bridge one binding beam 1 and another adjacent binding beam 1 and fixed to the flange portions 14 by bolt fastening or the like.
- the binding beam concrete 20 is placed in the groove portion that is configured by the pair of side plate portions 13 and the bottom plate portion 12 of the steel form 10 installed in the steel form installation step.
- concrete is poured into the groove portion of the steel form 10 while a vibrator is used for air bubble mixing prevention.
- concrete is simultaneously placed in the wooden form 2 a of the girder 2 and on the deck plate 3 , and then the binding beam 1 , the girder 2 , and the slab are integrally formed.
- the penetration step is performed as illustrated in FIG. 8( c ) .
- Formed in the penetration step is the web opening 40 penetrating the steel form 10 installed in the steel form installation step and the binding beam concrete 20 placed in the placement step.
- the side plate portion 13 of one Z-steel 11 , the binding beam concrete 20 , and the side plate portion 13 of the other Z-steel 11 are sequentially penetrated by means of an excavator (such as a known drill) after the concrete placed in the placement step realizes a predetermined strength, and the web opening 40 is formed as a result.
- the plurality of web openings 40 are formed by similar work being performed in a plurality of places of the beam.
- the number of the web openings 40 may correspond to the number of ducts to be disposed.
- the size and the position of disposition of the web opening 40 can be determined similarly to general RC.
- the maximum diameter of the web opening 40 is one-third or less of the height of the binding beam 1 (dimension D in FIG. 3 )
- the position of disposition is other than the end portion of the binding beam 1 (range to one-tenth of the total length of the binding beam 1 and range equivalent to twice the diameter of the web opening 40 from the end portion of the binding beam 1 )
- the interval between the plurality of web openings 40 is at least 1.5 times the total value of the respective diameters of the web openings 40 .
- the size and the position of disposition of the web opening 40 are not limited to the example and can be determined in any manner insofar as the required strength of the binding beam 1 can be ensured.
- a duct is passed through the web opening 40 formed in the penetration step.
- the passage of the duct (not illustrated) is performed by a known method and will not be described in detail. This is the end of the description of the binding beam construction method according to Embodiment 1.
- the steel form 10 having the groove portion can be formed by joining the pair of Z-steels 11 to each other on the joining surface of the bottom plate portion 12 , roll molding or press molding of a thin steel plate for groove portion formation can be omitted and the labor and cost required for the processing can be reduced.
- the groove portion can be formed by joining the pair of Z-steels 11 to each other at a construction site, and thus the pair of Z-steels 11 can be stacked and transported in a state where the frame members are not joined to each other. As a result, the number of the Z-steels 11 that can be transported at one time can be increased and the labor and cost required for the transport can be reduced.
- bottom plate portions 12 are joined to each other in a state where they are overlapped at the joining surface, when the binding beam concrete 20 is cast on the steel form 10 , leakage of the binding beam concrete 20 from the joint portion can be suppressed, and construction is improved. Further, by directly joining the bottom plate portions 12 each other, another plate or the like for connecting the bottom plate portions 12 to each other becomes unnecessary, and the cost required for joining can be reduced.
- the flange portion 14 Since the flange portion 14 is provided, the load of the slab supported by the binding beam 1 can be received by the flange portion 14 and is allowed to smoot flow to the binding beam 1 and the proof stress of the binding beam 1 is improved.
- the reinforcing portion 15 is provided at the outer end of the flange portion 14 , buckling of the flange portion 14 at a time when the binding beam concrete 20 is placed on the groove portion or the flange portion 14 of the steel form 10 can be suppressed by the reinforcing portion 15 and the proof stress of the binding beam 1 is improved.
- Embodiment 2 relates to a construction method in which a cylindrical form is pre-installed in the web opening forming portion and a web opening is formed in the place of cylindrical form installation by post-concrete placement cylindrical form removal.
- the configuration of the binding beam according to Embodiment 2 after completion is substantially the same as the configuration of the binding beam according to Embodiment 1, and regarding the configuration substantially the same as the configuration of Embodiment 1, the same reference numerals and/or names as those used in Embodiment 1 are attached thereto as necessary, and a description thereof will be omitted.
- the following description covers a steel form forming method and a binding beam construction method in relation to the binding beam according to Embodiment 2. Description will be appropriately omitted as to procedures similar to those of Embodiment 1.
- the Z-steel 11 is manufactured at a factory.
- a circular hole 51 is formed in advance at a position corresponding to the web opening forming portion in the Z-steel 11 .
- the circular hole 51 is provided at each of the positions six places in total in the drawing) in the side plate portion 13 of the Z-steel 11 that corresponds to the web opening 40 illustrated in FIG. 1( a ) by means of any tool such as a cutting machine.
- the Z-steel 11 having the circular holes 51 as described above is transported to a construction site, and then a pair of the Z-steels 11 transported to the construction site are bolt-joined together.
- the steel form 10 is formed as a result.
- the specific method for the joining is similar to that of Embodiment 1 and will not be described in detail.
- FIG. 9 is a set of cross-sectional perspective views corresponding to the A-A arrow cross section in FIG. 1( a ) .
- FIG. 9( a ) illustrates the binding beam 50 at the completion of steel form installation and cylindrical form installation steps.
- FIG. 9( b ) illustrates the binding beam 50 at the completion of main bar arrangement, deck plate installation, and placement steps.
- FIG. 9( c ) illustrates the binding beam 50 at the completion of a penetration step.
- the steel form installation step is similar to that of Embodiment 1 and will not be described in detail.
- a cylindrical form 52 is inserted into the circular hole 51 formed in the steel form 10 .
- the axial length of the cylindrical form 52 exceeds the width of the groove portion of the steel form 10 (length in the +X-X direction), and thus both end portions of the cylindrical form 52 protrude to the outside from the circular hole 51 as illustrated in the drawing.
- the cylindrical form 52 may be hollow or solid and any material can be used for the cylindrical form 52 insofar as the load of concrete can be withstood, the case of a solid wooden form will be described below.
- the gap between the outer periphery of the cylindrical form 52 and the inner periphery of the circular hole 51 is filled with a sealing material (not illustrated) such as putty. Concrete leakage is deterred as a result.
- the main bar arrangement, deck plate installation, and placement steps are performed as illustrated in FIG. 9( b ) .
- the main bar arrangement, deck plate installation, and placement steps can be carried out similarly to the main bar arrangement, deck plate installation, and placement steps according to Embodiment 1, respectively. Accordingly, detailed descriptions of the steps will be omitted.
- the penetration step is performed as illustrated in FIG. 9( c ) .
- Formed in the penetration step is the web opening 40 penetrating the steel form 10 installed in the steel form installation step and the concrete placed in the placement step.
- the cylindrical form 52 installed in the cylindrical form installation step is removed to the outside of the binding beam 50 after the concrete placed in the placement step realizes a predetermined strength.
- the web opening 40 is formed at the position where the cylindrical form 52 was present (web opening forming portion).
- a duct can be inserted through the hollow part of the steel form 10 , and thus the cylindrical form 52 may not be removed.
- a part of the duct may be used as the cylindrical form 52 .
- a duct is passed through the web opening 40 formed in the penetration step.
- the passage of the duct (not illustrated) is performed by a known method and will not be described in detail. This is the end of the description of the method for constructing the binding beam 50 according to Embodiment 2.
- the web opening 40 may be formed by the method according to Embodiment 1 (with a drill or the like) at the position in the binding beam 50 where the web opening 40 is not formed after the binding beam 50 is formed by the method according to Embodiment 2 (by pre-disposition of the cylindrical form 52 in the web opening forming portion).
- each portion of the binding beams 1 and 50 described in the detailed description of the invention and the drawings are merely examples, and any other dimensions, shapes, materials, ratios, and the like can be used as well.
- the front-view angle that is formed by the side plate portion 13 and the bottom plate portion 12 may be obtuse angles or acute angles although each of the angles is a right angle in each of the embodiments as illustrated in FIG. 1( b ) .
- FIG. 10 is a set of views illustrating a state where the Z-steel 11 is transported.
- FIG. 10( a ) is an end view illustrating the state of transport of the Z-steel 11 of Embodiment 1.
- FIG. 10( b ) is an end view illustrating the state of transport of a Z-steel 11 ′ according to a first modification example. In a state where the plurality of Z-steels 11 of Embodiment 1 are overlapped as illustrated in FIG.
- first overlap dimension an interval between one of straight lines connecting a plurality of outermost portions on one side of the Z-steel 11 and the straight line that is parallel to the straight line and passes through the outermost portion of the Z-steel 11 on the other side.
- the Z-steel 11 ′ in which each of the angle formed by the side plate portion 13 and the bottom plate portion 12 and the angle formed by the side plate portion 13 and the flange portion 14 is an obtuse angle is assumed as the Z-steel 11 ′ according to the first modification example, and in a state where a plurality of the Z-steels 11 ′ are overlapped, H′ (hereinafter, referred to as second overlap dimension) is an interval corresponding to the first overlap dimension H.
- the second overlap dimension H′ is smaller than the first overlap dimension H. Accordingly, transport efficiency improvement can be achieved by the Z-steel 11 ′ being formed as in FIG. 10( b ) .
- FIG. 1 is a set of views illustrating the steel form 10 according to a second modification example.
- FIG. 11( a ) is a plan view of the steel form 10 that is yet to be bent.
- FIG. 11( b ) is a side view of the steel form 10 that is bent.
- the pre-bending steel form 10 may be formed as one flat steel plate 60 as illustrated in FIG. 11( a ) .
- each of a boundary line L 1 between the side plate portion 13 and the bottom plate portion 12 , a boundary line L 2 between the side plate portion 13 and the flange portion 14 , and a boundary line L 3 between the flange portion 14 and the reinforcing portion 15 has a slit.
- the steel form. 10 that is illustrated in FIG.
- the steel form 10 can be, for example, transported as the flat steel plate 60 in FIG. 11( a ) . Accordingly, the overlap dimension of the steel form 10 in the state of transport decreases and transportation efficiency improvement can be achieved.
- the steel form 10 may be divided in one or more places in the longitudinal direction and joined at an installation site.
- the position and place of division of the steel form 10 can be determined in any manner.
- the steel form 10 may be divided into a plurality of units capable of being loaded on a transport vehicle in terms of length. It is preferable that the position of division is a place where the moment that is applied to the post-joining steel form 10 is small. Any joining method is applicable to the steel form 10 after the division.
- a pair of the steel forms 10 brought in touch with each other in the divided state may be connected via a connection plate (not illustrated) provided on the outside surfaces of the side plate portions 13 of the pair of steel forms 10 .
- a drill screw, a bolt, or the like can be used for fixing of the connection plate to the side plate portion 13 .
- the binding beam concrete 20 is placed in the post-joining steel form 10 , it is preferable to support the steel form 10 by using a temporary support at the joining point of the steel form 10 .
- the manufacturing workability and the transport efficiency of the steel form 10 can be improved.
- even the binding beam 1 that has a large span can be built by joining of a plurality of the standard-span binding beams 1 .
- FIG. 12 is a set of views illustrating the vicinity of the joining portion between a binding beam 100 and a girder 110 according to a third modification example.
- FIG. 12( a ) is a right side view and.
- FIG. 12( b ) is a cross-sectional view taken along arrow B-B in FIG. 12( a ) .
- the end portion of the binding beam 100 in the axial center direction (+Y-Y direction) is joined to the girder 110 , which is a steel-framed beam.
- a dustpan shaped member (dustpan member) 120 having a substantially U-shaped XZ cross section is joined by welding or the like to the side surface of the girder 110 .
- the binding beam 100 and the girder 110 can be joined together by the steel form 10 of the binding beam 100 being accommodated in the dustpan shaped member 120 .
- FIG. 13 is a set of views illustrating the vicinity of the joining portion between the binding beam 1 and the girder 110 according to a fourth modification example.
- FIG. 13( a ) is a right side view
- FIG. 13( b ) is a plan view
- the girder 110 is configured as reinforced concrete and disposed in the girder 110 are a plurality of the main bars 30 disposed along the longitudinal direction of the girder 110 and a rib 31 disposed in a direction orthogonal to the longitudinal direction and surrounding the plurality of main bars 30 (in FIG.
- a notch 111 for causing the girder 110 to swallow the tip of the binding beam 1 is formed in the place in the side portion of the girder 110 that corresponds to the binding beam 1 .
- the binding beam 1 is disposed so as to be orthogonal to the girder 110 and joined in part to the girder 110 via the notch 111 .
- the pair of side plate portions 13 of the binding beam 1 is accommodated in the girder 1 by a length L 10 , which is equal to or greater than the cover thickness of the girder 110 , beyond the side surface of the girder on the binding beam 1 side whereas the bottom plate portion 12 , the flange portion 14 , and the reinforcing portion 15 of the binding beam 1 stay at a position where the end surface on the girder 110 side is substantially flush with the side surface of girder on the binding beam 1 side.
- the “cover thickness” is the thickness part of concrete that reaches the rib 31 from the side surface of the girder 110 and is the thickness of a dimension L 11 in FIG. 13 .
- the girder 110 accommodating the binding beam 1 to the extent of the length L 10 , which is equal to or greater than the cover thickness Lil of the girder 110 , as described above.
- hairpin bars 17 are swallowed by the girder 110 .
- the hairpin bars 17 are a plurality of rod-shaped bar arrangements arranged side by side along the X direction.
- the hairpin bars 17 are passed through the arrangement holes (see reference numeral 13 a in FIG. 16 to be described later) formed in the pair of side plate portions 13 and fixed by welding or the like to the pair of side plate portions 13 .
- the hairpin bar 17 and the pair of side plate portions 13 surround the rib 31 at least in part.
- a movement of the hairpin bar 17 in the ⁇ Y direction is regulated by the rib 31 , and thus it is possible to further improve the joining strength of the binding beam 1 and the girder 110 by means of the bearing pressure of the hairpin bar 17 (local compressive force).
- FIG. 13 it is assumed that in the pair of side plate portions 13 , only the height part that is minimum required for disposition of a required number of the hairpin bars 17 (three in FIG.
- the binding beam 1 can be accommodated in the girder 110 by any method.
- concrete placement may be performed on the steel form 10 and the form of the girder 110 in a state where the end portion of the steel form 10 is accommodated in the form of the girder 110 via the notch portion 111 formed in the form of the girder 110 and the hairpin bar 17 is disposed to surround the rib 31 at least in part and fixed to the side plate portion 13 .
- FIG. 14 is a right side view illustrating the vicinity of the joining portion between the binding beam 1 and the girder 110 according to a fifth modification example (in the fifth modification example and sixth to eighth modification examples, places without description are similar to those of the fourth modification example).
- the pair of side plate portions 13 extend toward the girder 110 with the height as it is and the pair of side plate portions 13 are accommodated in the girder 110 to the extent of a length that is equal to or greater than the cover thickness of the girder 110 .
- FIG. 15 is a right side view illustrating the vicinity of the joining portion between the binding beam 1 and the girder 110 according to the sixth modification example.
- FIG. 16 is a perspective view of an end portion of the steel form 10 of the binding beam 1 in FIG. 15 . As illustrated in FIGS. 15 and 16 , in the binding beam 1 .
- the pair of side plate portions 13 extend toward the girder 110 with the height as it is (or a part of the bottom plate portion 12 is notched along with a part of the reinforcing portion 15 and the flange portion 14 of the steel form 10 ) and the pair of side plate portions 13 are accommodated in the girder 11 .
- 0 to the extent of the length L 10 which is equal to or greater than the cover thickness of the girder 110 .
- a part of the binding beam 1 accommodated in the girder 110 needs to be provided with a part receiving the bearing pressure of the hairpin bar 17 (bearing pressure effective part).
- the bearing pressure effective part may vary with the desired bearing pressure.
- the bearing pressure effective part has such a width, the possibility of interference with the rib 31 is low, and thus smooth swallowing into the girder 110 is possible.
- FIG. 17 is a right side view illustrating the vicinity of the joining portion between the binding beam 1 and the girder 110 according to the seventh modification example.
- the pair of side plate portions 13 in addition to the bottom plate portion 12 , the flange portion 14 , and the reinforcing portion 15 of the binding beam 1 has an end surface on the girder 110 side staying at a position substantially flush with the side surface of the girder 110 on the binding beam 1 side.
- a joining plate 19 is fixed, by any method including a drill screw and a bolt, to the outside surfaces of the pair of side plate portions 13 and only the joining plate 19 is accommodated in the girder 110 by the length L 11 , which is equal to or greater than the cover thickness of the girder 110 , beyond the side surface of the girder 110 on the binding beam 1 side.
- L 11 which is equal to or greater than the cover thickness of the girder 110 , beyond the side surface of the girder 110 on the binding beam 1 side.
- FIG. 18 is a side view illustrating the vicinity of the joining portion between each binding beam 1 and the girder 110 according to the eighth modification example.
- FIG. 19 is a plan view of FIG. 18 .
- the pair of binding beams 1 are connected to each other via a hairpin bar 17 ′ fixed from above to the flange 14 . Even in a case where a tensile force is applied to the binding beam 1 in a direction away from the girder 110 , the hairpin bar 17 ′ in this structure is capable of countering the tensile force.
- the binding beam concrete 20 and the girder concrete are placed at the same time.
- the invention is not limited thereto and the binding beam concrete 20 and the girder concrete may be placed one by one.
- the side surface of the solidified girder concrete may be chipped into a shape (hat shape) substantially corresponding to the axial cross-sectional shape of the binding beams 1 and 50 and the binding beam concrete 20 may be placed after the end portion of the steel form 10 of each of the binding beams 1 and 50 is installed at the chipped part.
- the flange portion 14 is provided in each embodiment, the flange portion 14 may be omitted and the steel form 10 may be configured as a member having a substantially U-shaped axial cross section.
- the flange portion 14 is provided at the upper end of the side plate portion 13 , the invention is not limited thereto and the flange portion 14 may be provided at a position other than the upper end (such as a position that is below the upper end by a predetermined distance (such as several centimeters)).
- reinforcing portion 15 is provided at the outer end of the flange portion 14 in each embodiment, the reinforcing portion 15 may be omitted in a case where the flange portion 14 is capable of enduring the load of concrete.
- reinforcing means for further reinforcing the flange portion 14 may be provided in addition to or instead of the reinforcing portion 15 .
- reinforcement may be performed by means of a reinforcing steel plate affixed to the upper surface or the lower surface of the flange portion 14 .
- the steel plate may be affixed through the forward-rearward direction of the flange portion 14 or may be intensively affixed only to a part particularly requiring proof stress (such as the vicinity of the middle of the flange portion 14 in the forward-rearward direction).
- FIG. 20 is a cross-sectional view corresponding to the A-A arrow cross section in FIG. 1( a ) and is a cross-sectional view of a steel form 210 of a binding beam 200 according to a ninth modification example.
- the steel form 210 is provided with a second reinforcing portion 216 .
- the second reinforcing portion 216 is a steel plate extending from the lower end of a reinforcing portion 215 toward a side plate portion 213 .
- the second reinforcing portion 216 being provided as described above, the local buckling of the outer end of the flange portion 14 that pertains to a case where the slab concrete 4 is placed and a flange portion 214 receives the load of a slab can be more effectively deterred.
- FIG. 21 is a cross-sectional view corresponding to the A-A arrow cross section in FIG. 1( a ) and is a cross-sectional view of the steel form 210 of the binding beam 200 according to a tenth modification example.
- the second reinforcing portion 216 is formed by the outer end of the flange portion 214 being folded back toward the side plate portion 213 and the reinforcing portion 215 is omitted.
- FIG. 22 is a set of cross-sectional views corresponding to the A-A arrow cross section in FIG. 1( a ) .
- FIG. 22( a ) is a cross-sectional view of the steel form 210 of the binding beam 200 according to an eleventh modification example.
- FIG. 22( b ) is a cross-sectional view of a steel form 310 of a binding beam 300 according to a twelfth modification example. In other words, as illustrated in FIG.
- the surfaces of bottom plate portions 221 of a pair of Z-steels 220 that are brought in touch with each other may be used as joining surfaces 222 and the surfaces may be joined by welding.
- end portions of bottom plate portions 321 of a pair of Z-steels 320 may be folded back upward, the inside surface of this folded part 322 may be combined as a joining surface 323 , and the folded part may be joined by means of a caulking fitting 324 in that state.
- drill screw or screw driving may be performed from below or above on the end portions of the bottom plate portions 321 of the pair of Z-steels 320 so that the end portions are joined to each other.
- the drill screw or the screw may be allowed to protrude by, for example, approximately several centimeters into the inner spaces of the pair of Z-steels 220 so that the joining strength between the Z-steel 220 and the binding beam concrete 20 placed in the inner space is further enhanced.
- FIG. 23 is a set of cross-sectional views corresponding to the A-A arrow cross section in FIG. 1( a ) .
- FIG. 23 is a set of cross-sectional views corresponding to the A-A arrow cross section in FIG. 1( a ) .
- FIG. 23( a ) illustrates a steel form 410 of a binding beam 400 according to a thirteenth modification example.
- FIG. 23( b ) illustrates a steel form 510 of a binding beam 500 according to a fourteenth modification example.
- a non-opening member 422 may be provided for connection between flange portions 421 of a pair of Z-steels 420 as illustrated in FIG. 23( a ) or a non-opening member 522 may be provided for connection between side plate portions 521 of a pair of Z-steels 520 as illustrated in FIG. 23( b ) .
- the non-opening member 522 illustrated in FIG. 23( b ) is preferably provided in the range (range of the dimension L 12 in FIG. 23( b ) ) from the upper end positions of the pair of side plate portions to the position that is below the upper end positions by one-third of the height of the pair of side plate portions.
- the side plate portion 13 is likely to pivot to the outside with the boundary between the bottom plate portion 12 and the side plate portion 13 as a fulcrum, and thus the distance between the pair of side plate portions 13 tends to increase as the upper end of the side plate portion 13 is approached.
- the relative positions of the pair of side plate portions 13 can be fixed at a position relatively close to the upper ends of the pair of side plate portions 13 , and thus the mutual outward opening of the pair of side plate portions 13 can be more effectively prevented than in a case where the non-opening member 522 is provided at a position below the range.
- the main bar arrangement step is performed after the steel form installation step.
- the invention is not limited thereto and the steel form installation step may be performed after the main bar arrangement step.
- the main bar 30 is disposed first in the main bar arrangement step, the pair of Z-steels 11 are disposed so as to cover the main bar 30 from below, and in a state where the bottom plate portions 12 of the pair of Z-steels 11 overlap each other, a bolt being inserted from below through the bottom plate portion 12 and thereby the pair of Z-steels 11 may be joined to each other.
- One embodiment of the present invention provides a steel form, which is a steel form for steel-framed concrete beam formation, includes a pair of frame members, wherein each of the pair of frame members is provided with a bottom plate portion and a side plate portion extending upward from the bottom plate portion, the bottom plate portion has a joining surface for joining the respective bottom plate portions of the pair of frame members to each other, and a groove portion allowing concrete placement is formed by the respective bottom and side plate portions of the pair of frame members.
- the steel form having the groove portion can be formed by joining the pair of frame members to each other on the joining surface of the bottom plate portion, roll molding or press molding of a thin steel plate for groove portion formation can be omitted and the labor and cost required for the processing can be reduced.
- the groove portion can be formed by joining the pair of frame members to each other at a construction site, and thus the pair of frame members can be stacked and transported in a state where the frame members are not joined to each other. As a result, the number of the frame members that can be transported at one time can be increased and the labor and cost required for the transport can be reduced.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein a part of the steel-framed concrete beam is joined to a girder, and the steel form is provided with an end portion on the girder side in a longitudinal direction of the steel form, accommodated in the girder via a notch formed in a side surface of the girder, and having a length equal to or greater than a cover thickness of the girder.
- the girder accommodating the binding beam to the extent of the length, which is equal to or greater than the cover thickness of the girder.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein a non-opening member for fixing the pair of side plate portions to each other is provided in a range from an upper end position of the pair of side plate portions to a position below the upper end position by one-third of a height of the pair of side plate portions.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein the steel form is provided with a flange portion extending outward from an upper end of the side plate portion.
- the flange portion since the flange portion is provided, load of a slab supported by the steel-framed concrete beam can be received by the flange portion and is allowed to smoothly flow to the steel-framed concrete beam and proof stress of the steel-framed concrete beam is improved.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein the steel form is provided with a reinforcing portion extending downward or upward from an outer end of the flange portion.
- the reinforcing portion is provided at the outer end of the flange portion, buckling of the flange portion at a time when the concrete is placed on the groove portion or the flange portion of the steel form can be suppressed by the reinforcing portion and the proof stress of the steel-framed concrete beam is improved.
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Abstract
Description
- The present application claims the benefit of Patent Application in Japan No. 2017-036750 filed on Feb. 28, 2017 and the benefit of PCT application No. PCT/JP2018/005971 filed on Feb. 20, 2018, the disclosure of which is incorporated by reference its entirety.
- All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
- The present invention relates to a steel form.
- Proposed in the related art is a method for using a grooved steel form (approximately U-shaped in cross section) matching the outer shell shape of a beam as a beam form for labor-saving form construction for example, Patent Document 1).
- Patent Document 1: Japanese Unexamined Patent Application Publication No. Heisei 10-140654
- The steel form described in
Patent Document 1 needs to be formed by processing a thin steel plate into a shape matching the outer shell shape of a beam by, for example, roll molding or press molding. As a result, it takes labor and cost to process the steel form. Besides, the grooved steel form is bulky in terms of transport, and thus the number of the grooved steel forms that can be transported at one time is limited. As a result, it takes labor and cost to transport the steel form. - It is an object of the present invention to solve the problems of the above mentioned prior arts.
- One aspect of the present invention provides a steel form, which is a steel form for steel-framed concrete beam formation, includes a pair of frame members, wherein each of the pair of frame members is provided with a bottom plate portion and a side plate portion extending upward from the bottom plate portion, the bottom plate portion has a joining surface for joining the respective bottom plate portions of the pair of frame members to each other, and a groove portion allowing concrete placement is formed by the respective bottom and side plate portions of the pair of frame members.
-
FIGS. 1(a) and 1(b) are a set of views illustrating a steel-framed concrete beam (binding beam) according toEmbodiment 1 of the invention, in whichFIG. 1(a) is a left side view andFIG. 1(b) is a cross-sectional view taken along arrow A-A inFIG. 1(a) . -
FIG. 2 is an exploded perspective view illustrating a temporary state during construction in the vicinity of the joining portion between the binding beam and a girder. -
FIG. 3 is a view illustrating the relationship between a cross section of the binding beam and calculation parameters. -
FIG. 4 is a graph showing the relationship between a slab thickness and a long-term bending rigidity ratio. -
FIG. 5 is a graph showing the relationship between the slab thickness and a short-term bending rigidity ratio. -
FIG. 6 is a graph showing the relationship between the load that is applied to the binding beam and the shear rigidity ratio of a steel form, which pertains to a case where no web opening is present. -
FIG. 7 is a graph showing the relationship between the load that is applied to the binding beam and the shear rigidity ratio of the steel form, which pertains to a case where a web opening is present. -
FIGS. 8(a)-8(c) are a set of cross-sectional perspective views corresponding to the A-A arrow cross section inFIG. 1(a) , in whichFIG. 8(a) illustrates the binding beam at the completion of a steel form installation step,FIG. 8(b) illustrates the binding beam at the completion of main bar arrangement, deck plate installation, and placement steps, andFIG. 8(c) illustrates the binding beam at the completion of a penetration step. -
FIGS. 9(a)-9(c) are a set of cross-sectional perspective views corresponding to the A-A arrow cross section inFIG. 1(a) , in whichFIG. 9(a) illustrates the binding beam at the completion of steel form installation and cylindrical form installation steps,FIG. 9(b) illustrates the binding beam at the completion of main bar arrangement, deck plate installation, and placement steps, andFIG. 9(c) illustrates the binding beam at the completion of a penetration step. -
FIGS. 10(a) and 10(b) are a set of views illustrating a state where a Z-steel is transported, in whichFIG. 10(a) is an end view illustrating the state of transport of a Z-steel ofEmbodiment 1 andFIG. 10(b) is an end view illustrating the state of transport of a Z-steel according to a first modification example. -
FIGS. 11(a) and 11(b) are a set of views illustrating a steel form according to a second modification example, in whichFIG. 11(a) is a plan view of the steel form that is yet to be bent andFIG. 11(b) is a side view of the steel form that is bent. -
FIGS. 12(a) and 12(b) are a set of views illustrating the vicinity of the joining portion between a binding beam and a girder according to a third modification example, in whichFIG. 12(a) is a left side view andFIG. 12(b) is a cross-sectional view taken along arrow B-B inFIG. 12(a) . -
FIGS. 13(a) and 13(b) are a set of views illustrating the vicinity of the joining on between a binding beam and a girder according to a fourth modification example, in whichFIG. 13(a) is a right side view andFIG. 13(b) is a plan view. -
FIG. 14 is a right side view illustrating the vicinity of the joining portion between a binding beam and a girder according to a fifth modification example. -
FIG. 15 is a right side view illustrating the vicinity of the joining portion between a binding beam and a girder according to a sixth modification example. -
FIG. 16 is a perspective view of an end portion of the steel form of the binding beam inFIG. 15 . -
FIG. 17 is a right side view illustrating the vicinity of the joining portion between a binding beam and a girder according to a seventh modification example. -
FIG. 18 is a side view illustrating the vicinity of the joining portion between a binding beam and a girder according to an eighth modification example. -
FIG. 19 is a plan view ofFIG. 18 . -
FIG. 20 is a cross-sectional view corresponding to the A-A arrow cross section inFIG. 1(a) and is a cross-sectional view of a steel form of a binding beam according to a ninth modification example. -
FIG. 21 is a cross-sectional view corresponding to the A-A arrow cross section inFIG. 1(a) and is a cross-sectional view of a steel form of a binding beam according a tenth modification example. -
FIGS. 22(a) and 22(b) are a set of cross-sectional views corresponding to the A-A arrow cross section inFIG. 1(a) , in whichFIG. 22(a) illustrates a steel form of a binding beam according to an eleventh modification example andFIG. 22(b) illustrates a steel form of a binding beam according to a twelfth modification example. -
FIGS. 23(a) and 23(b) are a set of cross-sectional views corresponding to the A-A arrow cross section inFIG. 1(a) , in whichFIG. 23(a) illustrates a steel form of a binding beam according to a thirteenth modification example andFIG. 3(b) illustrates a steel form of a binding beam according to a fourteenth modification example. - Embodiments of a steel form according to the invention will be described in detail below with reference to accompanying drawings. The basic concepts of the embodiments ([I]) will be described first, and then details of the embodiments ([II]) will be described. Modification examples regarding the embodiments ([III]) will be described last. The invention is not limited by the embodiments.
- The basic concepts of the embodiments will be described first.
- The embodiments relate to a steel form. The “steel form” is a form provided with steel for forming steel-framed concrete beams constituting building. The “steel-framed concrete beam” is a beam provided with at least a steel frame and concrete. The steel-framed concrete beam may be provided with a component other than the steel frame and the concrete. For example, the embodiments illustrate an example in which the steel-framed concrete beam is configured as a steel-framed reinforced concrete beam that has a rebar in addition to a steel frame and concrete. Although the steel-framed reinforced concrete beam may be provided with, for example, a main bar and a stirrup as the rebar, a case where the steel-framed reinforced concrete beam is provided with a main bar and no stirrup will be described below. The steel-framed concrete beam may be provided with, for example, a stirrup and no main bar, both a main bar and a stirrup, or no main bar and no stirrup.
- The steel frame is capable of having any shape insofar as the steel frame functions as a form allowing concrete placement. A case where the steel frame has an axial cross section in a hat shape (a shape obtained by joining a pair of Z-steels to each other) will be described below.
- The steel-framed concrete beam according to the embodiments is applicable to any installation floor. Although a case where the steel-framed concrete beam is a second floor beam will be described below, the steel-framed concrete beam is applicable to beams of other floors as well. Although a case where the steel-framed concrete beam is a binding beam will be described below, the steel-framed concrete beam may be a girder as well.
- Details of the embodiments will be described below
- The steel-framed concrete beam according to
Embodiment 1 will be described first. -
FIG. 1 is a set of views illustrating the steel-framed concrete beam according to Embodiment 1 (hereinafter, simply referred to as “binding beam” 1).FIG. 1(a) is a left side view andFIG. 1(b) is a cross-sectional view taken along arrow A-A in FIG. 1(a). As illustrated inFIG. 1 , thebinding beam 1 according toEmbodiment 1 is provided with asteel form 10, bindingbeam concrete 20,main bars 30, and web openings (through holes) 40. In the following description, the +X-X direction in each drawing will be referred to as “width direction” as necessary. In particular, the +X direction will be referred to as “rightward direction” and the −X direction will be referred to as “leftward direction”. The +Y-Y direction will be referred to as “depth direction” or “forward-rearward direction”. In particular, the +Y direction will be referred to as “forward direction” and the −Y direction will be referred to as “rearward direction”. The +Z-Z direction will be referred to as “height direction” or “upward-downward direction”. In particular, the +Z direction will be referred to as “upward direction” and the −Z direction will be referred to as “downward direction”. As for a vertical plane (YZ plane) passing through the axial center of the steel-framed concrete beam, the direction toward the plane along the width direction (+X-X) will be referred to as “inward direction” and the direction away from the plane along the width direction (+X-X) will be referred to as “outward direction”. - The
steel form 10 is a steel form that has a groove portion (described later) for placing thebinding beam concrete 20. Thissteel form 10 is provided in eachbinding beam 1 constituting a building and is disposed so as to cover thebinding beam 1 from below. As illustrated in the drawing, thesteel form 10 ofEmbodiment 1 is formed by a pair of (that is, two) Z-steels 11 being mutually joined in bottom plate portions 12 (described later) at a construction site. The invention is not limited thereto, and thesteel form 10 may be integrally formed with a single member or may be formed by three or more members being combined. In a case where three or more members are combined as described above, for example, the integrally formed members (thebottom plate portion 12, aside plate portion 13, aflange portion 14, and a reinforcingportion 15 to be described later) that constitute the Z-steel 11 may be formed separately. Each of the pair of Z-steels 11 can be substantially similar in configuration to the other, and thus only one of the Z-steels 11 will be described below. In a case where the Z-steels 11 need to be distinguished from each other, the Z-steel 11 that is positioned on the right of the binding beam 1 (in the +X direction) will be referred to as “right Z-steel” and the Z-steel 11 that is positioned on the left of the binding beam 1 (in the −X direction) will be referred to as “left Z-steel”. A specific method for forming thesteel form 10 will be described later. - The Z-
steel 11 is a frame member that constitutes thesteel form 10. As illustrated inFIG. 1(b) , the Z-steel 11 is a steel material that has a substantially Z-shaped axial cross section. The Z-steel 11 is provided with thebottom plate portion 12, theside plate portion 13, theflange portion 14, and the reinforcingportion 15. - The
bottom plate portion 12 is a steel plate positioned on the bottom surface of thesteel form 10. Thebottom plate portion 12 has a joiningsurface 16 for mutually joining the respectivebottom plate portions 12 of the pair of Z-steels 11. The pair of Z-steels 11 are joined to each other on the joiningsurface 16. For example, inEmbodiment 1, a part of thebottom plate portion 12 of the right Z-steel is superposed on a part of thebottom plate portion 12 of the left Z-steel and each of the parts where the pair of Z-steels 11 are in contact with each other (the upper surface of thebottom plate portion 12 of the left Z-steel and the lower surface of thebottom plate portion 12 of the right Z-steel) is the joiningsurface 16. The joining on the joiningsurface 16 can be performed by any specific method. For example, inEmbodiment 1, a plurality of bolt holes (not illustrated) are spaced apart along the longitudinal direction (+Y-Y direction) of the beam in the joiningsurfaces 16 of both Z-steels 11 and both Z-steels 11 are joined by bolt fastening by means of the bolt holes. Specific joining methods are not limited thereto. For example, welding-based joining and screw penetration-based joining may be performed instead. - The
side plate portion 13 is a steel plate extending in the upward direction from thebottom plate portion 12. Specifically, theside plate portion 13 is a part that is folded back from the outer end of thebottom plate portion 12 and extends to the upper end of the beam and is positioned so as to cover the left and right sides of thebinding beam 1. The length of theside plate portion 13 in the height direction (+Z-Z direction) is longer, by the thickness of thebottom plate portion 12, in the left Z-steel than in the right Z-steel. This is for the upper end positions of theside plate portions 13 of both Z-steels 11 (that is, the height positions of the flange portions 14) to coincide with each other when the pair of Z-steels 11 are overlapped. - In the following description, the part that is formed by the
side plate portions 13 and thebottom plate portions 12 of a pair of the steel forms 10 and has a U-shaped axial cross section will be referred to as groove portion as necessary. Concrete can be placed in the groove portion by thesteel form 10 forming the groove portion as described above. The lower and side parts of thebinding beam 1 are covered with a steel plate by the groove portion, and thus it is possible to deter steam from escaping from the lower and side parts of the binding beam concrete 20 during a fire, it is possible to deter a temperature rise in the room below thebinding beam 1, and it is possible to improve the fire resistance performance of thebinding beam 1. - The
flange portion 14 is a steel plate extending in the outward direction from the upper end of theside plate portion 13. Specifically, theflange portion 14 is a part that is folded back in the outward direction from the upper end of theside plate portion 13 and extends along a horizontal plane, and adeck plate 3 is placed and screwed on theflange portion 14. Although a case where thisdeck plate 3 is a known corrugated steel plate will be described, the invention is not limited thereto and a flat plate may be used as thedeck plate 3. Although illustration is omitted, the bindingbeams 1 are arranged side by side at intervals along the longitudinal direction of agirder 2, one end portion of thedeck plate 3 is placed in theflange portion 14 of onebinding beam 1 as illustrated inFIG. 1(b) , and the other end portion of thedeck plate 3 is similarly placed in theflange portion 14 of thebinding beam 1 that is adjacent to the onebinding beam 1. By theflange portion 14 being provided as described above, the load of slab concrete 4 (described later) can be received by theflange portion 14 and is allowed to smoothly flow to thebinding beam 1 and the proof stress of thebinding beam 1 is improved. - The reinforcing
portion 15 is a steel plate extending in the downward direction from the outer end of theflange portion 14. By the reinforcingportion 15 being provided as described above and thickness being given to the outer end of theflange portion 14, the local buckling of the outer end of theflange portion 14 that pertains to a case where theslab concrete 4 is placed and theflange portion 14 receives the load of the slab can be deterred. In addition, it is possible to reduce the overall thickness of thesteel form 10 by locally reinforcing only a low-strength part by means of the reinforcingportion 15. The reinforcingportion 15 ofEmbodiment 1 extends in the downward direction from the outer end of theflange portion 14. The invention is not limited thereto and the reinforcingportion 15 may extend in, for example, the upward direction. - The
binding beam concrete 20 is concrete placed in the groove portion that the pair ofside plate portions 13 and thebottom plate portion 12 of thesteel form 10 constitute. Thebinding beam concrete 20 is known concrete solidified after filling in the groove portion, and the plurality ofweb openings 40 are formed in the binding beam concrete 20 as described above. Theslab concrete 4 for forming an upper floor slab is formed along a horizontal plane above thebinding beam concrete 20. Girder concrete (reference numeral omitted) for forming thegirder 2 is formed, so as to be orthogonal to thebinding beam 1, at the front and rear ends of thebinding beam concrete 20. Although thebinding beam concrete 20, theslab concrete 4, and the girder concrete are given different names and reference numerals, thebinding beam concrete 20, theslab concrete 4, and the girder concrete are simultaneously placed and formed inEmbodiment 1. Thebinding beam concrete 20, theslab concrete 4, and the girder concrete will be simply referred to as “concrete” when no distinguishment among them is necessary. - The
main bars 30 are rebars extending along the axial center direction of the beam. Although two upper end bars and four lower end bars are illustrated as an example inEmbodiment 1, the number and disposition of themain bars 30 are not limited thereto. - The
web opening 40 is a hole formed so as to penetrate theside plate portion 13 and thebinding beam concrete 20. Theweb opening 40 is formed by, for example, theside plate portion 13 and the binding beam concrete 20 being drilled with a drill after the binding beam concrete 20 placed in thesteel form 10 is solidified. By theweb opening 40 being formed as described above, a duct or piping for air conditioning, electrical equipment, and so on can be passed through the web opening 40 (a case where a duct for air conditioning is passed through theweb opening 40 will be described below Accordingly, the duct can be extended from one of spaces sandwiching the beam 1 (such as the space to the right of the binding beam 1) to the other thereof (such as the space to the left of the binding beam 1) and the degree of freedom of duct disposition is improved. - The
web opening 40 is formed in the web opening forming portion of thebinding beam 1. The “web opening forming portion” is a part where theweb opening 40 penetrating theside plate portion 13 and the binding beam concrete 20 can be formed. Specifically, the “web opening forming portion” is a part where no rebar (main bar 30 in Embodiment 1) is arranged (part where the drill does not interfere with the rebar when theweb opening 40 is drilled with the drill). For example, inEmbodiment 1, the “web opening forming portion” is a part above the lower main bar 30 (lower end bar) in thebinding beam 1. The number of theweb openings 40 is six and theweb openings 40 are along the axial center direction of the beam in the illustration. The number of theweb openings 40 is not limited to six. - The joining portion between the
binding beam 1 and thegirder 2 according toEmbodiment 1 will be described below.FIG. 2 is an exploded perspective view illustrating a temporary state during construction in the vicinity of the joining portion between thebinding beam 1 and thegirder 2. The concrete and the rebar that constitute thebinding beam 1 and thegirder 2 are not illustrated inFIG. 2 for convenience of illustration. As illustrated inFIG. 2 , a notch (hereinafter, referred to as binding beamaccommodating portion 2 b) having a shape (hat shape) substantially corresponding to the axial cross-sectional shape of thebinding beam 1 is formed in a side surface of awooden form 2 a of thegirder 2 according toEmbodiment 1. Thebinding beam 1 and thegirder 2 can be formed at the same time by concrete being simultaneously placed in thewooden form 2 a of thegirder 2 and thesteel form 10 with thesteel form 10 of thebinding beam 1 fitted in the binding beamaccommodating portion 2 b. As illustrated in the drawing, notches (hereinafter, referred to as flange accommodating portions 2 c) having the same width as theflange portion 14 are formed on the left and right of the upper end of the binding beamaccommodating portion 2 b. Theflange portion 14 can be housed in the flange accommodating portion 2 c. In a case where theflange portion 14 is housed in the flange accommodating portion 2 c as described above, a gap equivalent to the height of the reinforcingportion 15 is formed below theflange portion 14. A sealingmaterial 2 d (illustrated rectangular wood or the like) filling this gap is disposed for prevention of concrete leakage from the gap. - Temporary supports (not illustrated) may support the
binding beam 1 until concrete placement. The positions and number of the temporary supports may be appropriately changed in accordance with the length and weight of thebinding beam 1. For example, one temporary support may be provided in one axial end portion, one temporary support may be provided in the other axial end portion, and one temporary support may be provided in the axial middle portion. Thesteel form 10 is higher in proof stress than thewooden form 2 a, and thus the temporary supports may be omitted if the temporary supports are unnecessary in view of the length and weight of thebinding beam 1. - Next, an example of a method for designing the
steel form 10 according toEmbodiment 1 will be described. In the present embodiment, the allowable bending moment or the allowable shear force of thebinding beam 1 is calculated by the following Equation (1). -
F a =F RC +β·F S (Equation 1) - Fa: allowable bending moment or allowable shear force of
binding beam 1 - FRC: allowable bending moment or allowable shear force of binding beam concrete 20 (hereinafter, referred to as reinforced concrete (“RC”) as necessary)
- β: burden factor of allowable bending moment or allowable shear force of
steel form 10, which is 0.5 or less - FS: allowable bending moment or allowable shear force of
steel form 10 - This design method will be divided into an allowable bending moment design method and an allowable shear force design method and described in further detail below. The allowable bending moment design method will be described first. The allowable bending moment is designed after division into a long-term allowable bending moment and a short-term allowable bending moment. The long-term allowable bending moment is calculated by the following Equation (2). The short-term allowable bending moment is calculated by the following Equation (3).
FIG. 3 is a view illustrating the relationship between the cross section of thebinding beam 1 and calculation parameters. -
L M a=L M RC+LβM·L M S (Equation 2) -
S M a=S M RC+SβM·S M S (Equation 3) - LMRC: long-term allowable bending moment of RC cross section part (which may be at·Lft·j in case where tensile rebar ratio of RC cross section is balanced rebar ratio or less)
- SMRC: short-term allowable bending moment of RC cross section part (which may be at·Sft·j in case where tensile rebar ratio of RC cross section is balanced rebar ratio or less)
- at: tensile rebar cross-sectional area
- Lft: long-term allowable tensile stress of tensile rebar
- Sft: short-term allowable tensile stress of tensile rebar
- j: stress center distance (j=(⅞)·d)
- d: effective depth of cross section (distance from upper surface of
binding beam 1 to concrete bar arrangement) - LβM: long-term steel frame bending burden effective factor of 0.5 or less, 0.1 here
- SβM: short-term steel frame bending burden effective factor of 0.5 or less, 0.4 here
- LMS: long-term allowable bending moment of S cross section part (LMS=Lσt·ZS)
- SMS: short-term allowable bending moment of S cross section part (SMS=Sσt·ZS)
- Lσt: long-term allowable tensile stress of
steel form 10 - Sσt: short-term allowable tensile stress of
steel form 10 - ZS: section modulus of
steel form 10 - An ultimate bending strength Mu is calculated by the following Equation (4),
-
M u =M uRC +M uS (Equation 4) - MuRC: ultimate bending strength of RC cross section part (MuRC=0.9·at·1.1·Sft·d)
- at: tensile rebar cross-sectional area
- Sft: short-term allowable tensile stress of tensile rebar
- d: effective depth of cross section
- MuS: ultimate bending strength of S cross section part (MuS=1.1·Sσt·Zp)
- Sσt: short-term allowable tensile stress of
steel form 10 - Zp: plastic section modulus of
steel form 10 - The long-term allowable bending moment is an allowable bending moment over a relatively long time (such as several years to several decades). The short-term allowable bending moment is an allowable bending moment over a relatively short time (such as several hours to several days). The allowable bending moment is calculated after the division into the two periods as described above so that an allowable bending moment suitable for each load bearing ratio is designed in view of the fact that the load bearing ratio of the RC and the
steel form 10 in thebinding beam 1 can vary as the situation of loading on thebinding beam 1 can vary with the lengths of the periods. In other words, it is assumed that the loading on thebinding beam 1 is relatively small in a relatively long time, and thus it is assumed that the RC of thebinding beam 1 is maintained without breaking (see the lower left cross section inFIG. 4 (described later)) and the load bearing ratio of the RC increases. In a relatively short time, it is assumed that the loading on thebinding beam 1 is relatively large (for example, the loading becomes relatively large by a forklift that carries a heavy object passing through the binding beam 1), and thus it is assumed that the load bearing ratio of the RC decreases as a result of cracking at the lower end of the RC of the binding beam 1 (see the lower left cross section inFIG. 5 (described later), as indicated by a diagonal line in this cross section, it is assumed that only approximately the upper two-thirds of the slab part of the RC remains without cracking and bears the load). In this regard, in the present embodiment, the load bearing ratio of the RC and thesteel form 10 in thebinding beam 1 is expressed inEquations binding beam 1. - The steel frame bending burden effective factor βM can be calculated from a bending rigidity ratio ζM(=ESIS/ECIC) of the RC and a bending rigidity ESIS of the
steel form 10. The bending rigidity ratio ζM can vary with the plate thickness of thesteel form 10 and the thickness of theslab concrete 4 attached to the binding beam 1 (hereinafter, referred to as “slab” as necessary), and thus an application restriction range is set for each of the plate thickness of thesteel form 10 and the thickness of the slab, the bending rigidity ratio ζM is calculated on the premise of the application restriction range, and the steel frame burden effective factor βM is determined from the calculated bending rigidity ratio ζM. Specifically, the plate thickness of thesteel form 10 has an application restriction range of 3.2 mm or more. The load bearing ratio of thesteel form 10 increases as the plate thickness of thesteel form 10 increases, and thus a lower limit value of “3.2 mm” and application restriction range setting “at or above” the lower limit value allow the steel frame burden effective factor βM to remain above it insofar as the plate thickness of thesteel form 10 is determined in the application restriction range. The thickness of the slab has an application restriction range of 200 mm or less. The ratio of load bearing by the slab increases as the thickness of the slab increases, and then the load bearing ratio of thesteel form 10 decreases. Accordingly, an upper limit value of “200 mm” and application restriction range setting “at or below” the upper limit value allow the steel frame burden effective factor βm to remain above it insofar as the thickness of the slab is determined in the application restriction range. -
FIG. 4 is a graph showing the relationship between the thickness of the slab and a long-term bending rigidity ratio LζM, andFIG. 5 is a graph showing the relationship between the thickness of the slab and a short-term bending rigidity ratio SζM. In each graph, the horizontal axis represents the thickness of the slab, the vertical axis represents the bending rigidity ratio ζM (long-term bending rigidity ratio LζM or short-term bending rigidity ratio SζM), the solid line indicates a load of 3.2 tons, and the dotted line indicates a load of 4.5 tons. It is assumed that the cross-sectional shape of thebinding beam 1 is a standard cross section (6.5 in in total length, 300 mm in total width, and 550 mm in total height). As shown inFIG. 4 , in the long term, the long-term bending rigidity ratio LζM is approximately 0.12 at 200 mm, which is the upper limit value of the application restriction range of the slab thickness, and thus the long-term bending rigidity ratio LζM was set to 0.1 in view of safety. As shown inFIG. 5 , in the short term, the short-term bending rigidity ratio SζM is approximately 0.49 at 200 mm, which is the upper limit value of the application restriction range of the slab thickness, and thus the short-term bending rigidity ratio SζMwas set to 0.4 in view of safety. Then, calculation can be performed based on the long-term bending rigidity ratio LζM of 0.1 and the short-term bending rigidity ratio SζM of 0.4 and in accordance with proof stress formula Ma=(1+LζM)MRC and steel frame bending burden effective factor βM=ζM(MRC/MS). Here, MRC/MS is the allowable proof stress ratio between the RC cross section and thesteel form 10 and MRC/MS is 1.35 in a case where the bar arrangement of the RC cross section is 4-HD13 (four deformed rebars (steel deformed bars) having a yield point of 345 N/mm2 or more) and the plate thickness of thesteel form 10 is 3.2 mm in the cross sections inFIGS. 4 and 5 . Here, the steel frame bending burden effective factor pm was calculated using MRC/MS=1.0 as a value of safety side. As described above, in the present embodiment, a simplified method (β method) is used in which the restriction of the application restriction range is applied to the plate thickness of thesteel form 10 and the thickness of the slab. Alternatively, a detail method (ζ method) may be adopted in which the bending rigidity ratio ζM is set in accordance with each cross-sectional shape (plate thickness of thesteel form 10, slab thickness, and bar arrangement) and the steel frame bending burden effective factor βM is calculated by using proof stress formula Ma=(1+LζM)MRC. Here, the design formula is determined on the safety side so that the design formula does not become complicated (low iron burden rate being set in terms of design). As confirmed by the inventor's experiment, the cross section part of thesteel form 10 is restrained by the RC cross section part and thesteel form 10 undergoes no lateral buckling as a thin plate, and thus a tensile stress ft is adopted as an allowable stress fb of the steel material of thesteel form 10. - Next, the allowable shear force design method will be described. The allowable shear force is designed after division into a long-term allowable shear force and a short-term allowable shear force similarly to the above idea related to the allowable bending moment. The long-term allowable shear force is calculated by the following Equation (5) and the short-term allowable shear force is calculated by the following Equation (6). The relationship between the cross section of the
binding beam 1 and calculation parameters is as illustrated inFIG. 3 . -
L Q a =α·A C·L f S+βQ·S A W·LσS (Equation 5) -
S Q a =α·A C S f S+βQ·S A W·Sσs (Equation 6) - α: additional factor by shear span ratio (M/Qd)
- AC: shear effective cross-sectional area of RC portion (AC=B·
j+ 2·B2·t) - Lfs: long-term allowable shear stress of concrete
- SfS: short-term allowable shear stress of concrete
- βQ: steel frame shear burden effective factor of 0.5 or less, 0.2 here
- SAW: shear cross-sectional area of steel form 10 (SAW=2·tS·(H−2·r))
- tS: thickness of steel plate
- r: curvature radius of corner of Z-
steel plate 11 - LσS: long-term allowable shear stress of steel material of Z-steel plate 11 (LσS=square root of Lσt/3)
- SσS: short-term allowable shear stress of steel material of Z-steel plate 11 (SσS=square root of Sσt/3)
- The shear effective cross-sectional area Ac of the RC portion used in the shear force calculation is the same cross section as the
binding beam 1 used in the experiment as illustrated inFIG. 3 and the cross-sectional area of the slab on the flange portion of thesteel form 10 may also be included. The steel frame shear burden effective factor βQ in the shear force calculation formula can be obtained from a shear rigidity ratio ζQ of thesteel form 10 indicated by the result of the inventor's experiment.FIG. 6 is a graph showing the relationship between the load that is applied to thebinding beam 1 and the shear rigidity ratio ζQ of thesteel form 10, which pertains to a case where the web opening (opening) 40 is absent.FIG. 7 is a graph showing the relationship between the load that is applied to thebinding beam 1 and the shear rigidity ratio ζQ of thesteel form 10, which pertains to a case where the web opening (opening) 40 is present. In each graph, the horizontal axis represents the applied load and the vertical axis represents the shear rigidity ratio ζQ. As is apparent fromFIGS. 6 and 7 , the shear rigidity ratio ζQ of thesteel form 10 is substantially constant at approximately 0.2 regardless of the presence or absence of theweb opening 40 and the magnitude of the applied load. Accordingly, in the present embodiment, the steel frame shear burden effective factor βQ was obtained with shear rigidity ratio ζQ set to 0.2. The steel frame shear burden effective factor βQ is calculated from βQ=ζQ(QRC/QS) by detail method (ζ method)-based proof stress formula QL=(1+LζQ)LQRC. Here, QRC/QS is the ratio between the shear capacity of thesteel form 10 and the RC cross section. QRC/QS is 1.04 in a case where the cross-sectional shape of thebinding beam 1 is a standard cross section (6.5 m in total length, 300 mm in total width, and 550 mm in total height) and the thickness of thesteel form 10 is 3.2 mm. Here, the steel frame shear burden effective factor βQ of 0.2 was calculated using QRC/QS=1.0 as a value of safety side. Also in this shear design formula, ζQ is constant at 0.2 as the detail method (ζ method) and obtainment is also possible from equation Qa=(1+ζQ)QRC obtained from the allowable proof stress of the RC cross section. As with the bending design formula, however, the steel frame burden effective factor was clarified in the design formula. - As described above, the long-term steel frame bending burden effective factor LβM is 0.1 and the short-term steel frame bending burden effective factor SβM is 0.4 in the design of the allowable bending moment. In the design of the allowable shear force, the steel frame shear burden effective factor βQ is 0.2. Although the burden factor β of the
steel form 10 may be another value, the upper limit of the load bearing ratio of thesteel form 10 is set to 50% and the burden factor β of thesteel form 10 is set to 0.5 or less for safety enhancement. The lower limit of the load bearing ratio of thesteel form 10 can be at least 10% in view of the graphs inFIGS. 6 and 7 and the burden factor β of thesteel form 10 can be set to 0.1 or more. However, thesteel form 10 may be used only as a form of thebinding beam concrete 20 and thesteel form 10 may be allowed to bear no load. In this case, the burden factor β of thesteel form 10 may be 0. By adopting the design method, it is possible to calculate a complex allowable bending moment and a complex allowable shear force taking the respective bearing ratios of thesteel form 10 and the binding beam concrete 20 into account and it is possible to optimize the design of thebinding beam 1. - Next, an example of the method for forming the
steel form 10 according toEmbodiment 1 will be described. First, the Z-steel 11 is manufactured at a factory. The Z-steel 11 can be manufactured by any specific method. For example, the Z-steel 11 can be formed by bending of one flat thin steel plate. Subsequently, the manufactured Z-steel 11 is transported to a construction site. At this time, a plurality of the Z-steels 11 can be transported in an overlapping manner, and thus it is possible to transport more Z-steels 11 at one time than in the case of transporting the pair of mutually joined Z-steels 11. Transport efficiency enhancement can be achieved as a result. - The sealing material (small piece) 2 d described with reference to
FIG. 2 may be attached to the lower part of theflange portion 14 by any method such as adhesion before the transport. In this case, the strength of theflange portion 14 or the reinforcingportion 15 can be enhanced by the sealingmaterial 2 d and deformation of theflange portion 14 or the reinforcingportion 15 attributable to a load or an impact during the transport can be prevented. For a similar purpose, a reinforcing material (not illustrated) similar in shape to the sealingmaterial 2 d may be provided at a predetermined interval below theflange portion 14 or a long reinforcing material (not illustrated) resulting from extension of the sealingmaterial 2 d in the Y direction inFIG. 2 may be provided below theflange portion 14. Such reinforcing materials may be removed after the transport or may be permanently fixed without removal. The strength of theflange portion 14 or the reinforcingportion 15 can be reduced to the same extent in a case where the strength of theflange portion 14 or the reinforcing portion 1.5 can be improved by such a reinforcing material being provided, and thus theflange portion 14 and the reinforcingportion 15 may be reduced in thickness or the dimension at which the reinforcingportion 15 extends from theflange portion 14 may be shortened. - Next, the pair of Z-
steels 11 transported to the construction site are joined together and thesteel form 10 is formed. Specifically, as illustrated inFIG. 1(b) , thebottom plate portions 12 of the right Z-steel and the left Z-steel are overlapped and, in that state, a bolt may be inserted through and fastened in each of bolt holes illustrated) formed at an appropriate interval at the overlapping part of bothbottom plate portions 12. When both Z-steels are joined in this manner, it is preferable to attach a member for maintaining a constant interval between the respectiveside plate portions 13 of the Z-steels 11. For example, a batten positioned in the groove portion and fixing the interval by propping theside plate portions 13 or a U-shaped veneer board fitted to the outer edge shape of the groove portion may be temporarily installed and removed after both Z-steels 11 are joined to each other. - A method for constructing the
binding beam 1 according toEmbodiment 1 will be described below.FIG. 8 is a set of cross-sectional perspective views corresponding to the A-A arrow cross section inFIG. 1(a) .FIG. 8(a) illustrates thebinding beam 1 at the completion of a steel form installation step.FIG. 8(b) illustrates thebinding beam 1 at the completion of main bar arrangement, deck plate installation, and placement steps,FIG. 8(c) illustrates thebinding beam 1 at the completion of a penetration step. - First, the steel form installation step is performed as illustrated in
FIG. 8(a) . In the steel form installation step, thesteel form 10 formed by the above-described forming method is lifted by a heavy machine or the like and installed at a beam construction position. InEmbodiment 1, the installation is performed such that an end portion of thesteel form 10 is connected to thewooden form 2 a of thegirder 2 as illustrated inFIG. 2 . For convenience of illustration, thesteel form 10 of thebinding beam 1 inFIG. 2 is illustrated as being tightly fit in the notch (binding beamaccommodating portion 2 b) of thewooden form 2 a of thegirder 2. However, the invention is not limited thereto. The binding beamaccommodating portion 2 b may be enlarged in the width direction so that insertion of thesteel form 10 into the binding beamaccommodating portion 2 b is facilitated and the space between thesteel form 10 and the binding beamaccommodating portion 2 b may be filled with wood or the like after the insertion of thesteel form 10. After thesteel form 10 is installed as described above, thesteel form 10 is supported by means of a temporary support so as to be capable of enduring the subsequent concrete placement. - Subsequently, the main bar arrangement, deck plate installation, and placement steps are performed as illustrated in
FIG. 8(b) . - The
main bars 30 are arranged in thesteel form 10 in the main bar arrangement step. Specifically, themain bars 30 are assembled, lifted by means of a heavy machine or the like, and dropped into and disposed in the groove portion. Likewise, the main bars 30 (not illustrated) of thegirder 2 are dropped into and disposed in thewooden form 2 a of thegirder 2. Then, themain bars 30 of thebinding beam 1 are bent in, for example, end portions and fixed to themain bars 30 of thegirder 2. - The
deck plates 3 are installed on theflange portions 14 of thesteel form 10 in the deck plate installation step. In the deck plate installation step, the plurality ofdeck plates 3 are placed on theflange portions 14 so as to bridge onebinding beam 1 and another adjacentbinding beam 1 and fixed to theflange portions 14 by bolt fastening or the like. - In the placement step, the
binding beam concrete 20 is placed in the groove portion that is configured by the pair ofside plate portions 13 and thebottom plate portion 12 of thesteel form 10 installed in the steel form installation step. Specifically, in this placement step, concrete is poured into the groove portion of thesteel form 10 while a vibrator is used for air bubble mixing prevention. As described above, inEmbodiment 1, concrete is simultaneously placed in thewooden form 2 a of thegirder 2 and on thedeck plate 3, and then thebinding beam 1, thegirder 2, and the slab are integrally formed. - Subsequently, the penetration step is performed as illustrated in
FIG. 8(c) . Formed in the penetration step is theweb opening 40 penetrating thesteel form 10 installed in the steel form installation step and the binding beam concrete 20 placed in the placement step. Specifically, in this penetration step, theside plate portion 13 of one Z-steel 11, thebinding beam concrete 20, and theside plate portion 13 of the other Z-steel 11 are sequentially penetrated by means of an excavator (such as a known drill) after the concrete placed in the placement step realizes a predetermined strength, and theweb opening 40 is formed as a result. Then, the plurality ofweb openings 40 are formed by similar work being performed in a plurality of places of the beam. The number of theweb openings 40 may correspond to the number of ducts to be disposed. - The size and the position of disposition of the
web opening 40 can be determined similarly to general RC. For example, it is preferable that the maximum diameter of theweb opening 40 is one-third or less of the height of the binding beam 1 (dimension D inFIG. 3 ), the position of disposition is other than the end portion of the binding beam 1 (range to one-tenth of the total length of thebinding beam 1 and range equivalent to twice the diameter of the web opening 40 from the end portion of the binding beam 1), and the interval between the plurality ofweb openings 40 is at least 1.5 times the total value of the respective diameters of theweb openings 40. The size and the position of disposition of theweb opening 40 are not limited to the example and can be determined in any manner insofar as the required strength of thebinding beam 1 can be ensured. - Lastly, a duct is passed through the
web opening 40 formed in the penetration step. The passage of the duct (not illustrated) is performed by a known method and will not be described in detail. This is the end of the description of the binding beam construction method according toEmbodiment 1. - As described above, in the
binding beam 1 ofEmbodiment 1, since thesteel form 10 having the groove portion can be formed by joining the pair of Z-steels 11 to each other on the joining surface of thebottom plate portion 12, roll molding or press molding of a thin steel plate for groove portion formation can be omitted and the labor and cost required for the processing can be reduced. Also, the groove portion can be formed by joining the pair of Z-steels 11 to each other at a construction site, and thus the pair of Z-steels 11 can be stacked and transported in a state where the frame members are not joined to each other. As a result, the number of the Z-steels 11 that can be transported at one time can be increased and the labor and cost required for the transport can be reduced. - In addition, it is possible to calculate a complex allowable bending moment and a complex allowable shear force taking the respective bearing ratios of the
steel form 10 and the binding beam concrete 20 into account and it is possible to optimize the design of thebinding beam 1. - Since the
bottom plate portions 12 are joined to each other in a state where they are overlapped at the joining surface, when thebinding beam concrete 20 is cast on thesteel form 10, leakage of the binding beam concrete 20 from the joint portion can be suppressed, and construction is improved. Further, by directly joining thebottom plate portions 12 each other, another plate or the like for connecting thebottom plate portions 12 to each other becomes unnecessary, and the cost required for joining can be reduced. - Since the
flange portion 14 is provided, the load of the slab supported by thebinding beam 1 can be received by theflange portion 14 and is allowed to smoot flow to thebinding beam 1 and the proof stress of thebinding beam 1 is improved. - Since the reinforcing
portion 15 is provided at the outer end of theflange portion 14, buckling of theflange portion 14 at a time when thebinding beam concrete 20 is placed on the groove portion or theflange portion 14 of thesteel form 10 can be suppressed by the reinforcingportion 15 and the proof stress of thebinding beam 1 is improved. - Next, a binding beam according to
Embodiment 2 will be described. Schematically,Embodiment 2 relates to a construction method in which a cylindrical form is pre-installed in the web opening forming portion and a web opening is formed in the place of cylindrical form installation by post-concrete placement cylindrical form removal. The configuration of the binding beam according toEmbodiment 2 after completion is substantially the same as the configuration of the binding beam according toEmbodiment 1, and regarding the configuration substantially the same as the configuration ofEmbodiment 1, the same reference numerals and/or names as those used inEmbodiment 1 are attached thereto as necessary, and a description thereof will be omitted. The following description covers a steel form forming method and a binding beam construction method in relation to the binding beam according toEmbodiment 2. Description will be appropriately omitted as to procedures similar to those ofEmbodiment 1. - First, an example of the method for forming the
steel form 10 according toEmbodiment 2 will be described. First, the Z-steel 11 is manufactured at a factory. At this time, acircular hole 51 is formed in advance at a position corresponding to the web opening forming portion in the Z-steel 11. In other words, inEmbodiment 2, thecircular hole 51 is provided at each of the positions six places in total in the drawing) in theside plate portion 13 of the Z-steel 11 that corresponds to theweb opening 40 illustrated inFIG. 1(a) by means of any tool such as a cutting machine. Subsequently, the Z-steel 11 having thecircular holes 51 as described above is transported to a construction site, and then a pair of the Z-steels 11 transported to the construction site are bolt-joined together. Thesteel form 10 is formed as a result. The specific method for the joining is similar to that ofEmbodiment 1 and will not be described in detail. - The method for constructing a
binding beam 50 according toEmbodiment 2 will be described below.FIG. 9 is a set of cross-sectional perspective views corresponding to the A-A arrow cross section inFIG. 1(a) .FIG. 9(a) illustrates thebinding beam 50 at the completion of steel form installation and cylindrical form installation steps.FIG. 9(b) illustrates thebinding beam 50 at the completion of main bar arrangement, deck plate installation, and placement steps.FIG. 9(c) illustrates thebinding beam 50 at the completion of a penetration step. - First, the steel form installation and cylindrical form installation steps are performed as illustrated in
FIG. 9(a) . The steel form installation step is similar to that ofEmbodiment 1 and will not be described in detail. - In the cylindrical form installation step, a
cylindrical form 52 is inserted into thecircular hole 51 formed in thesteel form 10. The axial length of the cylindrical form 52 (length in the direction) exceeds the width of the groove portion of the steel form 10 (length in the +X-X direction), and thus both end portions of thecylindrical form 52 protrude to the outside from thecircular hole 51 as illustrated in the drawing. Although thecylindrical form 52 may be hollow or solid and any material can be used for thecylindrical form 52 insofar as the load of concrete can be withstood, the case of a solid wooden form will be described below. After thecylindrical form 52 is installed as described above, the gap between the outer periphery of thecylindrical form 52 and the inner periphery of thecircular hole 51 is filled with a sealing material (not illustrated) such as putty. Concrete leakage is deterred as a result. - Subsequently, the main bar arrangement, deck plate installation, and placement steps are performed as illustrated in
FIG. 9(b) . The main bar arrangement, deck plate installation, and placement steps can be carried out similarly to the main bar arrangement, deck plate installation, and placement steps according toEmbodiment 1, respectively. Accordingly, detailed descriptions of the steps will be omitted. - Subsequently, the penetration step is performed as illustrated in
FIG. 9(c) . Formed in the penetration step is theweb opening 40 penetrating thesteel form 10 installed in the steel form installation step and the concrete placed in the placement step. Specifically, in this penetration step, thecylindrical form 52 installed in the cylindrical form installation step is removed to the outside of thebinding beam 50 after the concrete placed in the placement step realizes a predetermined strength. As a result, theweb opening 40 is formed at the position where thecylindrical form 52 was present (web opening forming portion). In a case where thecylindrical form 52 is given a hollow shape, a duct can be inserted through the hollow part of thesteel form 10, and thus thecylindrical form 52 may not be removed. In addition, a part of the duct may be used as thecylindrical form 52. - Lastly, a duct is passed through the
web opening 40 formed in the penetration step. The passage of the duct (not illustrated) is performed by a known method and will not be described in detail. This is the end of the description of the method for constructing thebinding beam 50 according toEmbodiment 2. - As described above, with the
binding beam 50 ofEmbodiment 2, it is possible to form theweb opening 40 simply by removing thecylindrical form 52 Accordingly, it is possible to simplify the work for forming theweb opening 40 at a construction site. - The embodiments according to the invention have been described. However, the specific configurations and means of the invention can be modified and improved in any manner within the scope of the technical idea of each invention described in the claims. Such modification examples will be described below.
- First of all, the problems to be solved by the invention and the effects of the invention are not limited to the above and may vary with the details of the implementation environment and configuration of the invention, and only some of the problems described above may be solved and only some of the effects described above may be achieved in some cases.
- The features of each embodiment and the features according to each of the following modification examples may be mutually replaced or one feature may be added to another. For example, the
web opening 40 may be formed by the method according to Embodiment 1 (with a drill or the like) at the position in thebinding beam 50 where theweb opening 40 is not formed after thebinding beam 50 is formed by the method according to Embodiment 2 (by pre-disposition of thecylindrical form 52 in the web opening forming portion). - The dimension, shape, material, ratio, and the like of each portion of the
binding beams side plate portion 13 and thebottom plate portion 12, the front-view angle that is formed by theside plate portion 13 and theflange portion 14, and the front-view angle that is formed by theflange portion 14 and the reinforcingportion 15 may be obtuse angles or acute angles although each of the angles is a right angle in each of the embodiments as illustrated inFIG. 1(b) . -
FIG. 10 is a set of views illustrating a state where the Z-steel 11 is transported.FIG. 10(a) is an end view illustrating the state of transport of the Z-steel 11 ofEmbodiment 1.FIG. 10(b) is an end view illustrating the state of transport of a Z-steel 11′ according to a first modification example. In a state where the plurality of Z-steels 11 ofEmbodiment 1 are overlapped as illustrated inFIG. 10(a) , H (hereinafter, referred to as first overlap dimension) an interval between one of straight lines connecting a plurality of outermost portions on one side of the Z-steel 11 and the straight line that is parallel to the straight line and passes through the outermost portion of the Z-steel 11 on the other side. As illustrated inFIG. 10(b) , the Z-steel 11′ in which each of the angle formed by theside plate portion 13 and thebottom plate portion 12 and the angle formed by theside plate portion 13 and theflange portion 14 is an obtuse angle is assumed as the Z-steel 11′ according to the first modification example, and in a state where a plurality of the Z-steels 11′ are overlapped, H′ (hereinafter, referred to as second overlap dimension) is an interval corresponding to the first overlap dimension H. The second overlap dimension H′ is smaller than the first overlap dimension H. Accordingly, transport efficiency improvement can be achieved by the Z-steel 11′ being formed as inFIG. 10(b) . -
FIG. 1 is a set of views illustrating thesteel form 10 according to a second modification example.FIG. 11(a) is a plan view of thesteel form 10 that is yet to be bent.FIG. 11(b) is a side view of thesteel form 10 that is bent. Thepre-bending steel form 10 may be formed as oneflat steel plate 60 as illustrated inFIG. 11(a) . In thesteel plate 60, each of a boundary line L1 between theside plate portion 13 and thebottom plate portion 12, a boundary line L2 between theside plate portion 13 and theflange portion 14, and a boundary line L3 between theflange portion 14 and the reinforcingportion 15 has a slit. The steel form. 10 that is illustrated inFIG. 11(b) can be formed by bending each portion of thesteel plate 60 in the slit by means of a known device or the like. In this case, thesteel form 10 may be, for example, transported as theflat steel plate 60 inFIG. 11(a) . Accordingly, the overlap dimension of thesteel form 10 in the state of transport decreases and transportation efficiency improvement can be achieved. - Alternatively, the
steel form 10 may be divided in one or more places in the longitudinal direction and joined at an installation site. The position and place of division of thesteel form 10 can be determined in any manner. For example, thesteel form 10 may be divided into a plurality of units capable of being loaded on a transport vehicle in terms of length. It is preferable that the position of division is a place where the moment that is applied to thepost-joining steel form 10 is small. Any joining method is applicable to thesteel form 10 after the division. For example, a pair of the steel forms 10 brought in touch with each other in the divided state may be connected via a connection plate (not illustrated) provided on the outside surfaces of theside plate portions 13 of the pair of steel forms 10. A drill screw, a bolt, or the like can be used for fixing of the connection plate to theside plate portion 13. In addition, when thebinding beam concrete 20 is placed in thepost-joining steel form 10, it is preferable to support thesteel form 10 by using a temporary support at the joining point of thesteel form 10. By the divided structure being adopted as described above, the manufacturing workability and the transport efficiency of thesteel form 10 can be improved. In addition, even thebinding beam 1 that has a large span can be built by joining of a plurality of the standard-span binding beams 1. - Although a case where the
girder 2 is a reinforced concrete beam has been described in each embodiment, the invention is not limited thereto and thegirder 2 may be, for example, a steel-framed beam.FIG. 12 is a set of views illustrating the vicinity of the joining portion between abinding beam 100 and agirder 110 according to a third modification example.FIG. 12(a) is a right side view and.FIG. 12(b) is a cross-sectional view taken along arrow B-B inFIG. 12(a) . As illustrated inFIG. 12 . in the third modification example, the end portion of thebinding beam 100 in the axial center direction (+Y-Y direction) is joined to thegirder 110, which is a steel-framed beam. Here, a dustpan shaped member (dustpan member) 120 having a substantially U-shaped XZ cross section is joined by welding or the like to the side surface of thegirder 110. Thebinding beam 100 and thegirder 110 can be joined together by thesteel form 10 of thebinding beam 100 being accommodated in the dustpan shapedmember 120. - Alternatively, the swallowing width of the
binding beam 1 in thegirder 110 may be further increased.FIG. 13 is a set of views illustrating the vicinity of the joining portion between thebinding beam 1 and thegirder 110 according to a fourth modification example.FIG. 13(a) is a right side view andFIG. 13(b) is a plan view As illustrated inFIG. 13 , thegirder 110 is configured as reinforced concrete and disposed in thegirder 110 are a plurality of themain bars 30 disposed along the longitudinal direction of thegirder 110 and arib 31 disposed in a direction orthogonal to the longitudinal direction and surrounding the plurality of main bars 30 (inFIG. 13(b) , only the outermostmain bars 30 in the Y direction are illustrated among themain bars 30 for convenience of illustration). Anotch 111 for causing thegirder 110 to swallow the tip of thebinding beam 1 is formed in the place in the side portion of thegirder 110 that corresponds to thebinding beam 1. Thebinding beam 1 is disposed so as to be orthogonal to thegirder 110 and joined in part to thegirder 110 via thenotch 111. Specifically, the pair ofside plate portions 13 of thebinding beam 1 is accommodated in thegirder 1 by a length L10, which is equal to or greater than the cover thickness of thegirder 110, beyond the side surface of the girder on thebinding beam 1 side whereas thebottom plate portion 12, theflange portion 14, and the reinforcingportion 15 of thebinding beam 1 stay at a position where the end surface on thegirder 110 side is substantially flush with the side surface of girder on thebinding beam 1 side. Here, the “cover thickness” is the thickness part of concrete that reaches therib 31 from the side surface of thegirder 110 and is the thickness of a dimension L11 inFIG. 13 . It is possible to further improve the joining strength of thebinding beam 1 and thegirder 110 by thegirder 110 accommodating thebinding beam 1 to the extent of the length L10, which is equal to or greater than the cover thickness Lil of thegirder 110, as described above. - In the example illustrated in
FIG. 13 , in particular, hairpin bars 17 are swallowed by thegirder 110. The hairpin bars 17 are a plurality of rod-shaped bar arrangements arranged side by side along the X direction. For the pair ofside plate portions 13 swallowed by thegirder 110 to be connected to each other, the hairpin bars 17 are passed through the arrangement holes (seereference numeral 13 a inFIG. 16 to be described later) formed in the pair ofside plate portions 13 and fixed by welding or the like to the pair ofside plate portions 13. When thehairpin bar 17 is disposed at a position closer to the Y-direction middle position of thegirder 110 than the rib 31 (position on the -Y direction side), in particular, thehairpin bar 17 and the pair ofside plate portions 13 surround therib 31 at least in part. in this structure, a movement of thehairpin bar 17 in the ±Y direction is regulated by therib 31, and thus it is possible to further improve the joining strength of thebinding beam 1 and thegirder 110 by means of the bearing pressure of the hairpin bar 17 (local compressive force). In the example illustrated inFIG. 13 , it is assumed that in the pair ofside plate portions 13, only the height part that is minimum required for disposition of a required number of the hairpin bars 17 (three inFIG. 13 ) is accommodated in thegirder 110. Accordingly, the unnecessary height part has anotch 18 formed therein and notched. Thebinding beam 1 can be accommodated in thegirder 110 by any method. For example, concrete placement may be performed on thesteel form 10 and the form of thegirder 110 in a state where the end portion of thesteel form 10 is accommodated in the form of thegirder 110 via thenotch portion 111 formed in the form of thegirder 110 and thehairpin bar 17 is disposed to surround therib 31 at least in part and fixed to theside plate portion 13. - Alternatively, the pair of
side plate portions 13 may be simply accommodated in thegirder 110 with the height as it is and without thenotch 18 being provided.FIG. 14 is a right side view illustrating the vicinity of the joining portion between thebinding beam 1 and thegirder 110 according to a fifth modification example (in the fifth modification example and sixth to eighth modification examples, places without description are similar to those of the fourth modification example). As illustrated inFIG. 14 , in thebinding beam 1, the pair ofside plate portions 13 extend toward thegirder 110 with the height as it is and the pair ofside plate portions 13 are accommodated in thegirder 110 to the extent of a length that is equal to or greater than the cover thickness of thegirder 110. - Alternatively, a part of the pair of
side plate portions 13 and a bearing pressure effective part may be swallowed by thegirder 110.FIG. 15 is a right side view illustrating the vicinity of the joining portion between thebinding beam 1 and thegirder 110 according to the sixth modification example.FIG. 16 is a perspective view of an end portion of thesteel form 10 of thebinding beam 1 inFIG. 15 . As illustrated inFIGS. 15 and 16 , in thebinding beam 1. the pair ofside plate portions 13 extend toward thegirder 110 with the height as it is (or a part of thebottom plate portion 12 is notched along with a part of the reinforcingportion 15 and theflange portion 14 of the steel form 10) and the pair ofside plate portions 13 are accommodated in the girder 11.0 to the extent of the length L10, which is equal to or greater than the cover thickness of thegirder 110. In this structure, a part of thebinding beam 1 accommodated in thegirder 110 needs to be provided with a part receiving the bearing pressure of the hairpin bar 17 (bearing pressure effective part). The bearing pressure effective part may vary with the desired bearing pressure. For example, the width of the bearing pressure effective part is set to approximately 100 mm (=sum of an X-direction width L12, 50 mm, of a part of theflange portion 14 left without being cut and an X-direction width L13, 50 mm, of a part of thebottom plate portion 12 left without being cut). When the bearing pressure effective part has such a width, the possibility of interference with therib 31 is low, and thus smooth swallowing into thegirder 110 is possible. - Alternatively, the part to be swallowed in the
girder 110 may be retrofitted.FIG. 17 is a right side view illustrating the vicinity of the joining portion between thebinding beam 1 and thegirder 110 according to the seventh modification example. As illustrated inFIG. 17 , the pair ofside plate portions 13 in addition to thebottom plate portion 12, theflange portion 14, and the reinforcingportion 15 of thebinding beam 1 has an end surface on thegirder 110 side staying at a position substantially flush with the side surface of thegirder 110 on thebinding beam 1 side. Here, a joiningplate 19 is fixed, by any method including a drill screw and a bolt, to the outside surfaces of the pair ofside plate portions 13 and only the joiningplate 19 is accommodated in thegirder 110 by the length L11, which is equal to or greater than the cover thickness of thegirder 110, beyond the side surface of thegirder 110 on thebinding beam 1 side. In this structure, it is not necessary to perform processing such as providing of a notch for thesteel form 10 that has a complicated shape and the joiningplate 19 has only to be retrofitted in theside plate portion 13, which leads to easy construction. - The
binding beams 1 disposed on both sides of thegirder 110 may be connected to each other.FIG. 18 is a side view illustrating the vicinity of the joining portion between eachbinding beam 1 and thegirder 110 according to the eighth modification example.FIG. 19 is a plan view ofFIG. 18 . As illustrated inFIGS. 18 and 19 , provided on both sides of thegirder 110 are the pair ofbinding beams 1 disposed along a direction orthogonal to the longitudinal direction of thegirder 110 and the pair ofbinding beams 1 are disposed at positions on the same straight line that correspond to each other and brought in touch with thegirder 110. The pair ofbinding beams 1 are connected to each other via ahairpin bar 17′ fixed from above to theflange 14. Even in a case where a tensile force is applied to thebinding beam 1 in a direction away from thegirder 110, thehairpin bar 17′ in this structure is capable of countering the tensile force. - In each of the embodiments, the
binding beam concrete 20 and the girder concrete are placed at the same time. However, the invention is not limited thereto and thebinding beam concrete 20 and the girder concrete may be placed one by one. In a case where the girder concrete is placed first, for example, the side surface of the solidified girder concrete may be chipped into a shape (hat shape) substantially corresponding to the axial cross-sectional shape of thebinding beams steel form 10 of each of thebinding beams - Although the
flange portion 14 is provided in each embodiment, theflange portion 14 may be omitted and thesteel form 10 may be configured as a member having a substantially U-shaped axial cross section. Although theflange portion 14 is provided at the upper end of theside plate portion 13, the invention is not limited thereto and theflange portion 14 may be provided at a position other than the upper end (such as a position that is below the upper end by a predetermined distance (such as several centimeters)). - Although the reinforcing
portion 15 is provided at the outer end of theflange portion 14 in each embodiment, the reinforcingportion 15 may be omitted in a case where theflange portion 14 is capable of enduring the load of concrete. In addition, reinforcing means for further reinforcing theflange portion 14 may be provided in addition to or instead of the reinforcingportion 15. For example, reinforcement may be performed by means of a reinforcing steel plate affixed to the upper surface or the lower surface of theflange portion 14. The steel plate may be affixed through the forward-rearward direction of theflange portion 14 or may be intensively affixed only to a part particularly requiring proof stress (such as the vicinity of the middle of theflange portion 14 in the forward-rearward direction). - Alternatively, the shape of the reinforcing
portion 15 may be changed.FIG. 20 is a cross-sectional view corresponding to the A-A arrow cross section inFIG. 1(a) and is a cross-sectional view of asteel form 210 of abinding beam 200 according to a ninth modification example. As illustrated inFIG. 20 , thesteel form 210 is provided with a second reinforcingportion 216. The second reinforcingportion 216 is a steel plate extending from the lower end of a reinforcingportion 215 toward aside plate portion 213. By the second reinforcingportion 216 being provided as described above, the local buckling of the outer end of theflange portion 14 that pertains to a case where theslab concrete 4 is placed and aflange portion 214 receives the load of a slab can be more effectively deterred. In addition, it is possible to reduce the overall thickness of thesteel form 210 by locally reinforcing only a low-strength part by means of the second reinforcingportion 216. - The second reinforcing
portion 216 can be provided in another aspect as well.FIG. 21 is a cross-sectional view corresponding to the A-A arrow cross section inFIG. 1(a) and is a cross-sectional view of thesteel form 210 of thebinding beam 200 according to a tenth modification example. In the example illustrated inFIG. 21 , the second reinforcingportion 216 is formed by the outer end of theflange portion 214 being folded back toward theside plate portion 213 and the reinforcingportion 215 is omitted. - In each embodiment, the pair of Z-
steels 11 are overlapped with each other and bolt-joined. Specific methods for the joining are not limited thereto.FIG. 22 is a set of cross-sectional views corresponding to the A-A arrow cross section inFIG. 1(a) .FIG. 22(a) is a cross-sectional view of thesteel form 210 of thebinding beam 200 according to an eleventh modification example.FIG. 22(b) is a cross-sectional view of asteel form 310 of abinding beam 300 according to a twelfth modification example. In other words, as illustrated inFIG. 22(a) , the surfaces ofbottom plate portions 221 of a pair of Z-steels 220 that are brought in touch with each other may be used as joiningsurfaces 222 and the surfaces may be joined by welding. Alternatively, as illustrated inFIG. 22(b) , end portions ofbottom plate portions 321 of a pair of Z-steels 320 may be folded back upward, the inside surface of this foldedpart 322 may be combined as a joiningsurface 323, and the folded part may be joined by means of a caulking fitting 324 in that state. Alternatively, drill screw or screw driving may be performed from below or above on the end portions of thebottom plate portions 321 of the pair of Z-steels 320 so that the end portions are joined to each other. In this case, the drill screw or the screw may be allowed to protrude by, for example, approximately several centimeters into the inner spaces of the pair of Z-steels 220 so that the joining strength between the Z-steel 220 and the binding beam concrete 20 placed in the inner space is further enhanced. - A point that has been described in each embodiment is that a temporary member (member removed before concrete placement) such as a batten and a U-shaped veneer board is provided for fixing of the relative positions of the pair of Z-
steels 11 during the formation of the steel form 10 (mutual joining of the pair of Z-steels 11). A permanent member for fixing the relative positions of the pair of Z-steels 11 (member embedded without pre-concrete placement removal, hereinafter, referred to as non-opening member) may be provided instead of or in addition to the temporary member.FIG. 23 is a set of cross-sectional views corresponding to the A-A arrow cross section inFIG. 1(a) .FIG. 23(a) illustrates asteel form 410 of abinding beam 400 according to a thirteenth modification example.FIG. 23(b) illustrates asteel form 510 of abinding beam 500 according to a fourteenth modification example. in other words, anon-opening member 422 may be provided for connection betweenflange portions 421 of a pair of Z-steels 420 as illustrated inFIG. 23(a) or anon-opening member 522 may be provided for connection betweenside plate portions 521 of a pair of Z-steels 520 as illustrated inFIG. 23(b) . When the relative positions of the pairs of Z-steels non-opening members steels binding beam concrete 20. - The
non-opening member 522 illustrated inFIG. 23(b) , in particular, is preferably provided in the range (range of the dimension L12 inFIG. 23(b) ) from the upper end positions of the pair of side plate portions to the position that is below the upper end positions by one-third of the height of the pair of side plate portions. in a case where the pairs of Z-steels side plate portion 13 is likely to pivot to the outside with the boundary between thebottom plate portion 12 and theside plate portion 13 as a fulcrum, and thus the distance between the pair ofside plate portions 13 tends to increase as the upper end of theside plate portion 13 is approached. By thenon-opening member 522 being provided in the above-described range, however, the relative positions of the pair ofside plate portions 13 can be fixed at a position relatively close to the upper ends of the pair ofside plate portions 13, and thus the mutual outward opening of the pair ofside plate portions 13 can be more effectively prevented than in a case where thenon-opening member 522 is provided at a position below the range. - In each embodiment, the main bar arrangement step is performed after the steel form installation step. However, the invention is not limited thereto and the steel form installation step may be performed after the main bar arrangement step. At this time, the
main bar 30 is disposed first in the main bar arrangement step, the pair of Z-steels 11 are disposed so as to cover themain bar 30 from below, and in a state where thebottom plate portions 12 of the pair of Z-steels 11 overlap each other, a bolt being inserted from below through thebottom plate portion 12 and thereby the pair of Z-steels 11 may be joined to each other. - One embodiment of the present invention provides a steel form, which is a steel form for steel-framed concrete beam formation, includes a pair of frame members, wherein each of the pair of frame members is provided with a bottom plate portion and a side plate portion extending upward from the bottom plate portion, the bottom plate portion has a joining surface for joining the respective bottom plate portions of the pair of frame members to each other, and a groove portion allowing concrete placement is formed by the respective bottom and side plate portions of the pair of frame members.
- According to this embodiment, since the steel form having the groove portion can be formed by joining the pair of frame members to each other on the joining surface of the bottom plate portion, roll molding or press molding of a thin steel plate for groove portion formation can be omitted and the labor and cost required for the processing can be reduced. Also, the groove portion can be formed by joining the pair of frame members to each other at a construction site, and thus the pair of frame members can be stacked and transported in a state where the frame members are not joined to each other. As a result, the number of the frame members that can be transported at one time can be increased and the labor and cost required for the transport can be reduced.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein an allowable bending moment or an allowable shear three of the steel-framed concrete beam is calculated by Equation (1) below: (Equation 1) Fa=FRC+β·FS wherein, Fa: an allowable bending moment or an allowable shear force of the steel-framed concrete beam, FRC: an allowable bending moment or an allowable shear force of the concrete, β: a burden factor of an allowable bending moment or an allowable shear force of the steel form, which is 0.5 or less, and Fs: an allowable bending moment or an allowable shear force of the steel form.
- According to this embodiment, it is possible to calculate a complex allowable bending moment and a complex allowable shear force taking the respective bearing ratios of the steel form and the concrete into account and it is possible to optimize the design of the steel-framed concrete beam.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein a part of the steel-framed concrete beam is joined to a girder, and the steel form is provided with an end portion on the girder side in a longitudinal direction of the steel form, accommodated in the girder via a notch formed in a side surface of the girder, and having a length equal to or greater than a cover thickness of the girder.
- According to this embodiment, it is possible to further improve the joining strength of a binding beam and a girder by the girder accommodating the binding beam to the extent of the length, which is equal to or greater than the cover thickness of the girder.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein a non-opening member for fixing the pair of side plate portions to each other is provided in a range from an upper end position of the pair of side plate portions to a position below the upper end position by one-third of a height of the pair of side plate portions.
- According to this embodiment, since relative positions of the pair of side plate portions can be fixed at a position relatively close to the upper end position of the pair of side plate portions, mutual outward opening of the pair of side plate portions can be more effectively prevented than in a case where the non-opening member is provided at a position below this range.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein the steel form is provided with a flange portion extending outward from an upper end of the side plate portion.
- According to this embodiment, since the flange portion is provided, load of a slab supported by the steel-framed concrete beam can be received by the flange portion and is allowed to smoothly flow to the steel-framed concrete beam and proof stress of the steel-framed concrete beam is improved.
- Another embodiment of the present invention provides the steel form according to the above embodiment, wherein the steel form is provided with a reinforcing portion extending downward or upward from an outer end of the flange portion.
- According to this embodiment, since the reinforcing portion is provided at the outer end of the flange portion, buckling of the flange portion at a time when the concrete is placed on the groove portion or the flange portion of the steel form can be suppressed by the reinforcing portion and the proof stress of the steel-framed concrete beam is improved.
-
- 1 Binding beam
- 2 Girder
- 2 a Wooden form
- 2 b Binding beam accommodating portion
- 2 c Flange accommodating portion
- 2 d Sealing material
- 3 Deck plate
- 4 Slab concrete
- 10 Steel form
- 11, 11′ Z-steel
- 12 Bottom plate portion
- 13 Side plate portion
- 13 a Arrangement hole
- 14 Flange portion
- 15 Reinforcing portion
- 16 Joining surface
- 17, 17′ Hairpin bar
- 18 Notch
- 19 Joining plate
- 20 Binding beam concrete
- 30 Main bar
- 31 Rib
- 40 Web opening
- 50 Binding beam
- 51 Circular hole
- 52 Cylindrical form
- 60 Steel plate
- 100 Binding beam
- 110 Girder
- 111 Notch
- 120 Dustpan shaped member
- 200 Binding beam
- 210 Steel form
- 213 Side plate portion
- 214 Flange portion
- 215 Reinforcing portion
- 216 Second reinforcing portion
- 220 Z-steel
- 221 Bottom plate portion
- 222 Joining surface
- 300 Binding beam
- 310 Steel form
- 320 Z-steel
- 321 Bottom plate portion
- 322 Folded part
- 323 Joining surface
- 324 Caulking fitting
- 400 Binding beam
- 410 Steel form
- 420 Z-steel
- 421 Flange portion
- 422 Non-opening member
- 500 Binding beam
- 510 Steel form p0 520 Z-steel
- 521 Side plate portion
- 522 Non-opening member
Claims (6)
F a =F RC +β·F S (Equation 1)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2017-036750 | 2017-02-28 | ||
JP2017036750 | 2017-02-28 | ||
PCT/JP2018/005971 WO2018159382A1 (en) | 2017-02-28 | 2018-02-20 | Steel form |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2018/005971 Continuation-In-Part WO2018159382A1 (en) | 2017-02-28 | 2018-02-20 | Steel form |
Publications (1)
Publication Number | Publication Date |
---|---|
US20190376283A1 true US20190376283A1 (en) | 2019-12-12 |
Family
ID=63370141
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US16/549,310 Abandoned US20190376283A1 (en) | 2017-02-28 | 2019-08-23 | Steel form |
Country Status (5)
Country | Link |
---|---|
US (1) | US20190376283A1 (en) |
JP (1) | JP7185617B2 (en) |
SG (1) | SG11201907585PA (en) |
TW (1) | TWI678450B (en) |
WO (1) | WO2018159382A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11560725B2 (en) * | 2018-01-29 | 2023-01-24 | Inquik Ip Holdings Pty Ltd | Formwork brace |
Citations (8)
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US2233291A (en) * | 1939-10-14 | 1941-02-25 | Leebov Nathan | Building structure |
US4211045A (en) * | 1977-01-20 | 1980-07-08 | Kajima Kensetsu Kabushiki Kaisha | Building structure |
US20020026764A1 (en) * | 2000-08-15 | 2002-03-07 | Sachs Melvin H. | Composite column or beam framing members for building construction |
WO2007068063A1 (en) * | 2005-12-12 | 2007-06-21 | Bluescope Steel Limited | Formwork |
US20130283721A1 (en) * | 2012-04-25 | 2013-10-31 | Tae Sang Ahn | Steel frame structure using u-shaped composite beam |
US20140298749A1 (en) * | 2011-03-23 | 2014-10-09 | Entek Pty Ltd | Beam and a method for reinforcing concrete slabs |
US20150184379A1 (en) * | 2008-01-24 | 2015-07-02 | Nucor Corporation | Composite joist floor system |
US10323368B2 (en) * | 2015-05-21 | 2019-06-18 | Lifting Point Pre-Form Pty Limited | Module for a structure |
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JPS5883751A (en) * | 1981-11-10 | 1983-05-19 | 清水建設株式会社 | Construction of beam in building |
JPS6375231A (en) * | 1986-09-17 | 1988-04-05 | 鹿島建設株式会社 | Building housing |
JPH05179704A (en) * | 1991-12-26 | 1993-07-20 | Maeda Corp | Connection of large src precast beam with small precast beam |
JPH10140654A (en) * | 1996-11-09 | 1998-05-26 | Nippon Kokan Light Steel Kk | Driven form made of thin steel plate |
TW320667B (en) * | 1996-12-28 | 1997-11-21 | Chii-Luen Gau | A form plate fabric for prefabricated concrete |
KR100936403B1 (en) | 2009-05-15 | 2010-01-12 | 주식회사 성현케미칼 | Formed steel plate concrete beam having fire-resistant coating material attaching structure and construction method thereof |
JP2014101654A (en) | 2012-11-19 | 2014-06-05 | Nisshin A & C Co Ltd | Reinforcement structure of concrete and reinforcement method |
-
2018
- 2018-02-20 SG SG11201907585PA patent/SG11201907585PA/en unknown
- 2018-02-20 JP JP2019502899A patent/JP7185617B2/en active Active
- 2018-02-20 WO PCT/JP2018/005971 patent/WO2018159382A1/en active Application Filing
- 2018-02-27 TW TW107106684A patent/TWI678450B/en active
-
2019
- 2019-08-23 US US16/549,310 patent/US20190376283A1/en not_active Abandoned
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2233291A (en) * | 1939-10-14 | 1941-02-25 | Leebov Nathan | Building structure |
US4211045A (en) * | 1977-01-20 | 1980-07-08 | Kajima Kensetsu Kabushiki Kaisha | Building structure |
US20020026764A1 (en) * | 2000-08-15 | 2002-03-07 | Sachs Melvin H. | Composite column or beam framing members for building construction |
WO2007068063A1 (en) * | 2005-12-12 | 2007-06-21 | Bluescope Steel Limited | Formwork |
US20150184379A1 (en) * | 2008-01-24 | 2015-07-02 | Nucor Corporation | Composite joist floor system |
US20140298749A1 (en) * | 2011-03-23 | 2014-10-09 | Entek Pty Ltd | Beam and a method for reinforcing concrete slabs |
US20130283721A1 (en) * | 2012-04-25 | 2013-10-31 | Tae Sang Ahn | Steel frame structure using u-shaped composite beam |
US10323368B2 (en) * | 2015-05-21 | 2019-06-18 | Lifting Point Pre-Form Pty Limited | Module for a structure |
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US11560725B2 (en) * | 2018-01-29 | 2023-01-24 | Inquik Ip Holdings Pty Ltd | Formwork brace |
Also Published As
Publication number | Publication date |
---|---|
TWI678450B (en) | 2019-12-01 |
WO2018159382A1 (en) | 2018-09-07 |
TW201835427A (en) | 2018-10-01 |
SG11201907585PA (en) | 2019-09-27 |
JPWO2018159382A1 (en) | 2019-12-19 |
JP7185617B2 (en) | 2022-12-07 |
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