JP7637500B2 - Composite Beam - Google Patents

Description

The present invention relates to a composite beam having wooden members.

There are cases where it is required to provide through holes for equipment in wooden beams made of wood materials such as laminated lumber (see, for example, Patent Document 1).

JP 2017-75458 A

However, because wood materials have low shear strength, it is difficult to create large-diameter through holes in wooden beams. In addition, for fire resistance, the inner surface of the through hole needs to be fire-resistant coated, so the effective diameter of the through hole (the diameter of the through hole that can actually be used) is reduced by the thickness of the fire-resistant coating.

Taking the above facts into consideration, the present invention aims to construct a composite beam having wooden members with multiple large through holes.

The composite beam according to the first aspect has a wooden beam section whose end section has a higher beam depth than the middle section, a concrete beam section provided on the upper surface of the middle section of the wooden beam section, a shear force transmission section provided on the boundary surface between the wooden beam section and the concrete beam section, and a through hole formed in the concrete beam section that penetrates the concrete beam section in the beam width direction.

According to the composite beam of the first aspect, a concrete beam section is provided on the upper surface of the middle section of the wooden beam section, where the beam depth is low, and the wooden beam section and the concrete beam section are integrated by enabling shear force transmission between the wooden beam section and the concrete beam section using a shear force transmission section. This makes it possible to construct a composite beam with improved rigidity and strength. It is also possible to obtain a composite effect between the wooden beam section and the concrete beam section, making it possible to reduce the beam depth of the composite beam.

In addition, during an earthquake, the wooden beam and concrete beam tend to shift horizontally, but because the end face of the concrete beam touches the part of the wooden beam where the beam depth is high, it works together with the shear force transmission section to suppress the horizontal shift between the wooden beam and the concrete beam.

Furthermore, since the through holes for passing equipment piping and the like are formed in the concrete beam section, large through holes can be formed, and since there is no need to apply a fireproof coating to the inner surface of the through holes, the through holes formed do not become small. As a result, a composite beam with multiple large through holes and wooden members can be constructed.

The composite beam according to the second aspect is the composite beam according to the first aspect, in which a slab is provided so as to protrude from the upper end of the concrete beam section in the beam width direction of the concrete beam section.

The composite beam according to the second aspect can achieve a composite effect between the wooden beam section, the concrete beam section, and the slab. This allows the beam width of the composite beam to be reduced.

The composite beam of the third aspect is the composite beam of the first or second aspect, in which the concrete beam portion is made of precast members.

The composite beam according to the third aspect allows for efficient construction of the composite beam on-site.

The present invention has the above configuration, so it is possible to construct a composite beam with wooden members that has multiple large through holes.

FIG. 1 illustrates a side view of a composite beam according to an embodiment. This is a cross-sectional view taken along line 2-2 of Figure 1. This is a cross-sectional view taken along line 3-3 in Figure 1. This is a cross-sectional view taken along line 4-4 in Figure 1. FIG. 1 is a perspective view showing a column-beam joint structure according to one embodiment. FIG. 11 is a diagram showing moment values with respect to load point deflection obtained by a load test according to one embodiment. FIG. 13 is a side view showing a test specimen B used in a load test according to one embodiment. 1A-1D are cross-sectional views illustrating variations of a composite beam according to one embodiment. FIG. 13 is a side view showing a variation of a composite beam according to an embodiment. FIG. 11 is a side view showing a variation of a wooden beam according to an embodiment.

Below, we will explain a composite beam according to one embodiment with reference to the drawings.

(Composite beam)
As shown in the side view of Figure 1, Figure 2, which is a cross-sectional view taken along line 2-2 of Figure 1, Figure 3, which is a cross-sectional view taken along line 3-3 of Figure 1, and Figure 4, which is a cross-sectional view taken along line 4-4 of Figure 1, the composite beam 10 is composed of a wooden beam portion 12, a concrete beam portion 14, a shear force transmission portion 16, and a number of through holes 18, 20.

The wooden beam section 12 is composed of a wooden beam lower member 34 and a wooden beam upper member 36 provided on the upper surface of the end of the wooden beam lower member 34. The wooden beam lower member 34 and the wooden beam upper member 36 are formed from laminated wood, which is a wood material.

The wooden beam section 12 has a higher beam depth at the ends 22, 24 than at the middle section 26. In other words, the wooden beam section 12 has a so-called inverted drop haunch shape with a non-uniform cross section between the ends 22, 24 and the middle section 26.

The concrete beam section 14 is made of reinforced concrete and is provided on the upper surface of the middle section 26 of the wooden beam section 12. The concrete beam section 14 is formed by pouring cast-in-place concrete on the upper surface of the middle section 26 of the wooden beam section 12.

The shear force transmission section 16 is provided near the boundary surface 28 between the middle section 26 of the wooden beam section 12 and the concrete beam section 14. The shear force transmission section 16 is composed of multiple drift pins 30 as shear keys, with their lower ends embedded in the wooden beam section 12 and their upper ends embedded in the concrete beam section 14.

The multiple drift pins 30 are arranged at a predetermined interval in the beam length direction (hereinafter referred to as "beam length direction Y1") of the composite beam 10, the wooden beam section 12, and the concrete beam section 14. This allows the transmission of shear force in the beam length direction Y1 between the wooden beam section 12 and the concrete beam section 14.

In addition, the drift pins 30 arranged at the end of the intermediate section 26 of the wooden beam section 12 are arranged more densely (at shorter intervals) in the beam length direction Y1 than the drift pins 30 arranged in the middle of the intermediate section 26 of the wooden beam section 12. This is because the shear force generated near the end upper surface (boundary surface 28) of the intermediate section 26 of the wooden beam section 12 is greater than the shear force generated near the middle upper surface (boundary surface 28) of the intermediate section 26 of the wooden beam section 12, which allows the shear force in the beam length direction Y1 to be efficiently transmitted between the wooden beam section 12 and the concrete beam section 14.

The through holes 18, 20 are formed in the concrete beam section 14 located above the middle section 26 of the wooden beam section 12. The through holes 18, 20 are formed near the upper surface (boundary surface 28) of the middle section 26 of the wooden beam section 12 so as to penetrate the concrete beam section 14 in the beam width direction of the composite beam 10, the wooden beam section 12, and the concrete beam section 14 (hereinafter referred to as the "beam width direction X1").

The composite beam 10 is provided with a reinforced concrete slab 32 that protrudes from the upper end of the concrete beam section 14 in the beam width direction X1. The slab 32 is formed by pouring cast-in-place concrete.

As shown in the perspective views of Figures 1, 2, and 5, the wooden beam lower member 34 is a rectangular prism-shaped member that spans the entire length of the wooden beam 12. At the end of the wooden beam lower member 34, a vertical slit 38 is formed that penetrates the wooden beam lower member 34 from the center of the upper surface of the end in the beam width direction X1 to the center of the lower surface of the end in the beam width direction X1 and opens at the end face side. In addition, at the end of the wooden beam lower member 34, a plurality of through holes 40 that penetrate the wooden beam lower member 34 in the beam width direction X1 are formed so as to be arranged in a circle.

The wooden beam upper member 36 is a rectangular prism-shaped member that spans the entire length of the ends 22, 24 of the wooden beam 12. The wooden beam upper member 36 has a vertical slit 42 that penetrates the wooden beam upper member 36 from the center of the upper surface in the beam width direction X1 to the center of the lower surface in the beam width direction X1 and opens at the end face side. In addition, the wooden beam upper member 36 has a plurality of through holes 44 that penetrate the wooden beam upper member 36 in the beam width direction X1 and are arranged in a circular shape.

The end of the wooden beam lower member 34 and the wooden beam upper member 36 are joined and integrated by bonding the upper surface of the end of the wooden beam lower member 34 to the lower surface of the wooden beam upper member 36 with an adhesive. When the end of the wooden beam lower member 34 and the wooden beam upper member 36 are joined and integrated, the vertical slit 38 of the wooden beam lower member 34 and the vertical slit 42 of the wooden beam upper member 36 communicate to form one vertical slit 46.

The composite beam 10 is joined to the column 50 by a column-beam joint structure 48. The column 50 is composed of an upper column 52 and a lower column 54 connected vertically by a joint member 58. The upper column 52 and the lower column 54 are formed from laminated timber, which is a wood material.

The beam-column joint structure 48 is composed of a joint member 56 and a joint member 58. The joint member 56 is composed of an H-shaped steel 60 and a steel flat plate 62 that protrudes at the upper end and is joined to the end face of the H-shaped steel 60.

The web 64 of the H-shaped steel 60 has a plurality of through holes 66, 68 arranged in a circular shape that penetrate the web 64 in the beam width direction X1. In addition, the upper end of the flat plate 62 has a plurality of through holes 70 that penetrate the flat plate 62 in the beam length direction Y1.

The wooden beam 12 is moved laterally so that the web 64 of the H-shaped steel 60 is inserted into the vertical slit 46 of the wooden beam 12 until the end face of the wooden beam 12 faces the back face of the flat plate 62 (the face on the H-shaped steel 60 side) with a small gap, and is placed on the upper surface of the lower flange 72 of the H-shaped steel 60. In this state, drift pins 74 are inserted into the communicating through holes 40, 44 of the wooden beam 12 and the through holes 66, 68 of the H-shaped steel 60, fixing the end of the wooden beam 12 to the joint member 56, and filling the gap between the end face of the wooden beam 12 and the back face of the flat plate 62 with grout.

The joint member 58 is composed of an H-shaped steel 76, a steel flat plate 80 that extends horizontally to the left and right from the upper end of the web 78 of the H-shaped steel 76 in a plan view, and a steel flat plate 82 that is provided on the flat plate 80 and joined to the web 78 of the H-shaped steel 76 so as to form a cross shape with the web 78 in a plan view.

The upper end of the flange 84 of the H-shaped steel 76 has a plurality of through holes 86 that penetrate the flange 84 in the column direction of the column 50 (hereinafter referred to as "column direction Y2"). In addition, the web 78 of the H-shaped steel 76 has a plurality of through holes 88, 90 that penetrate the web 78 in the column width direction of the column 50 (hereinafter referred to as "column width direction X2").

A vertical slit 92 is formed at the upper end of the lower column 54, extending downward from the center of the lower column 54 in the column width direction X2 on the upper end surface of the lower column 54. In addition, a plurality of through holes 94 are formed at the upper end of the lower column 54, penetrating the lower column 54 in the column width direction X2.

At the lower end of the upper column 52, a vertical slit 96 that is cross-shaped in plan view and extends upward from the lower end surface of the upper column 52 is formed. In addition, at the lower end of the upper column 52, a plurality of through holes 98 are formed that penetrate the upper column 52 in the column width direction X2.

The joint member 58 is moved downward so that the web 78 of the H-shaped steel 76 is inserted into the vertical slit 92 of the lower column 54 until the bottom surface of the flat plate 80 faces the top surface of the lower column 54 with a small gap. In this state, a drift pin 100 is inserted into the communicating through hole 94 of the lower column 54 and the through hole 90 of the web 78 of the H-shaped steel 76 to fix the top end of the lower column 54 to the joint member 58, and grout is filled into the gap between the bottom surface of the flat plate 80 and the top surface of the lower column 54.

The upper column 52 is moved downward so that the web 78 of the H-shaped steel 76 and the flat plate 82 are inserted into the vertical slit 96 of the upper column 52 until the lower end surface of the upper column 52 faces the upper surface of the flat plate 80 with a small gap. In this state, a drift pin 100 is inserted into the communicating through hole 98 of the upper column 52 and the through hole 88 of the web 78 of the H-shaped steel 76 to fix the lower end of the upper column 52 to the joint member 58, and grout is filled into the gap between the lower end surface of the upper column 52 and the upper surface of the flat plate 80.

The joint member 58 and the connecting member 56 are joined by fitting the flange surface of the flange 84 of the joint member 58 to the plate surface of the flat plate 62 of the connecting member 56, and then passing the bolt 102 through the through hole 86 of the flange 84 and the through hole 70 of the flat plate 62 and screwing it into the nut 104 and tightening it.

As shown in FIG. 1, a plurality of stud bolts 110 are provided on the upper surface of the upper flange 106 of the H-shaped steel 60 constituting the connecting member 56 so as to be embedded in the concrete beam section 108 formed on the upper surface of the upper flange 106 by reinforced concrete, enhancing the integration of the connecting member 56 and the concrete beam section 108. Note that the stud bolts 108 are omitted from the connecting member 56 shown in FIG. 5.

(effect)
Next, the effects of this embodiment will be described.

According to the composite beam 10 of this embodiment, as shown in FIG. 1, a concrete beam section 14 is provided on the upper surface of the intermediate section 26 of the wooden beam section 12, which has a low beam thickness, and the wooden beam section 12 and the concrete beam section 14 are integrated by enabling shear force transmission between the wooden beam section 12 and the concrete beam section 14 by the shear force transmission section 16. This makes it possible to construct a composite beam with improved rigidity and strength. In addition, a composite effect can be obtained between the wooden beam section 12 and the concrete beam section 14, and the beam thickness of the composite beam 10 can be reduced.

The graph in FIG. 6 shows the results of a loading test performed on a test specimen A (not shown) having a similar configuration to the composite beam 10 of this embodiment, and a test specimen B as a comparative example. Value 112 indicates the moment M with respect to the load point deflection σ at the loading point when the center of test specimen A is loaded, and value 114 indicates the moment M with respect to the load point deflection σ at the loading point when the center of test specimen B is loaded.

As shown in the side view of Figure 7, specimen B is a composite beam 10 of this embodiment, in which the wooden beam portion 12 (see Figure 1) is a wooden beam portion 116 that does not have a drop haunch shape at both ends and has a uniform cross section over the entire beam length, and the other configuration is almost the same as that of the composite beam 10.

In other words, specimen B is composed of a wooden beam section 116 composed only of a wooden beam lower member 34, a concrete beam section 14 formed on the upper surface of this wooden beam section 116 over the entire beam length, a shear force transmission section 16, and multiple through holes 18, 20, and a slab 32 is provided so as to protrude from the upper end of the concrete beam section 14 in the beam width direction of the concrete beam section 14.

From the values 112 and 114 in Figure 6, it can be seen that test specimen A has greater rigidity and strength than test specimen B, and this shows that the composite beam 10 of this embodiment is a composite beam with improved rigidity and strength.

In addition, as shown in FIG. 1, according to the composite beam 10 of this embodiment, during an earthquake, the wooden beam section 12 and the concrete beam section 14 tend to shift horizontally. However, since the end face of the concrete beam section 14 abuts against the high beam depth part (upper member 36 of the wooden beam section) at the end of the wooden beam section 12, it cooperates with the shear force transmission section 16 to suppress the horizontal shift between the wooden beam section 12 and the concrete beam section 14.

Furthermore, according to the composite beam 10 of this embodiment, as shown in FIG. 1, the through holes 18, 20 for passing equipment piping and the like are formed in the concrete beam section 14, so that large through holes can be formed, and since there is no need to apply a fireproof coating to the inner surface of the through holes, the through holes formed do not become small. As a result, a composite beam having a wooden member (wooden beam section 12) with multiple large through holes can be constructed.

In addition, according to the composite beam 10 of this embodiment, as shown in FIG. 1, the through holes 18, 20 for passing equipment piping, etc. are formed near the top surface of the wooden beam portion 12, i.e., near the neutral axis of the composite beam 10, where no large stress occurs, so that reinforcement of the through holes can be reduced or eliminated, and larger through holes can be formed.

Furthermore, according to the composite beam 10 of this embodiment, as shown in Figures 1 to 4, the slab 32 is provided so as to protrude from the upper end of the concrete beam section 14 in the beam width direction (beam width direction X1) of the concrete beam section 14, so that a composite effect of the wooden beam section 12, the concrete beam section 14, and the slab 32 can be obtained. This makes it possible to reduce the beam width of the composite beam 10.

(Modification)
Next, a modification of the above embodiment will be described.

In the above embodiment, as shown in FIG. 1, an example is shown in which the wooden beam section 12 is formed from laminated timber, but the wooden beam section 12 may be any member made of wood. For example, as shown in the cross-sectional view of FIG. 8, the wooden beam section 12 may be configured to have a wooden beam core material 118 that serves as a load-bearing section, a fire-retardant layer 120 provided around the beam core material 118, and a wooden substitute fire layer 122 provided around the fire-retardant layer 120. The fire-retardant layer 120 is configured by alternately arranging wooden boards 124 and mortar boards 126.

When a fire breaks out in the wooden beam section 12, the fuel layer 122 burns and carbonizes, and the carbonized fuel layer 122 suppresses the transfer of heat from the outside of the fuel layer 122 to the beam core material 118. Furthermore, the fire-stopping layer 120 prevents flames and heat from penetrating the beam core material 118 from the outside of the fuel layer 122. This suppresses the temperature rise of the beam core material 118 during and after a fire, and stops the beam core material 118 from burning.

In the above embodiment, as shown in FIG. 1, an example was shown in which both ends (ends 22, 24) of the wooden beam section 12 have a drop haunch shape, but it is sufficient that at least one end of the wooden beam section 12 has a drop haunch shape.

For example, as shown in the side view of FIG. 9, the end 22 of the wooden beam section 12 may have a drop haunch shape, and the end 24 of the wooden beam section 12 may have a shape in which the cross section of the middle section 26 is equal to the cross section of the end 24 over the entire length of the end 24 in the beam length direction Y1.

In this example, the right end of the composite beam 128 is joined to a wooden beam 130 by a joining member 132. The joining member 132 is composed of a joining plate 136 attached to the side of the beam 130 by a screw member 134 such as a lag screw, and a gusset plate 138 provided on the plate surface of the joining plate 136 so as to protrude from this plate surface.

The right end of the composite beam 128 is joined to the beam 130 by fixing the wooden beam section 12 to a gusset plate 138 of a joining member 132 inserted into a slit (not shown) formed in the end face of the wooden beam section 12 with a drift pin 140. Note that the beam 130 may be a member of other structures such as reinforced concrete, steel-reinforced concrete, and steel frame construction.

In addition, in the above embodiment, as shown in FIG. 1, an example was shown in which the wooden beam section 12 was formed by combining the wooden beam section lower member 34 and the wooden beam section upper member 36, but the members that are combined to form the wooden beam section 12 may be members of any shape.

For example, as shown in the side view of FIG. 10, the wooden beam section 12 may be constructed by integrating a wooden beam section intermediate member 142 that constitutes the middle portion 26 of the wooden beam section 12 and a wooden beam section end member 144 that constitutes the ends 22, 24 of the wooden beam section 12 with a joining member 146.

In addition, in the above embodiment, as shown in FIG. 1, an example was shown in which the concrete beam section 14 was made of reinforced concrete, but the concrete beam section 14 may be made of fire-resistant concrete. For example, the concrete beam section 14 may be a steel-reinforced concrete member using CT steel, or a precast concrete member such as a steel-reinforced concrete member or a steel-reinforced concrete member. If the concrete beam section 14 is a precast member, the composite beam 10 can be efficiently constructed on-site.

In the above embodiment, as shown in FIG. 1, an example was shown in which the shear force transmission unit 16 was configured using a drift pin 30, but the shear force transmission unit 16 may be configured to transmit shear force in the beam length direction Y1 between the wooden beam portion 12 and the concrete beam portion 14. For example, the shear force transmission unit 16 may be configured using a lag screw, a headed stud bolt, a cotter, etc.

In addition, in the above embodiment, as shown in FIG. 1, an example was shown in which the slab 32 was a reinforced concrete slab formed from cast-in-place concrete, but the slab 32 may be of other structures, such as a precast concrete slab or a deck slab.

In the above embodiment, as shown in FIG. 1, an example was shown in which the pillars 50 (upper pillars 52 and lower pillars 54) were wooden members made of laminated timber, but the pillars 50 may also be members of other structures, such as reinforced concrete structures or steel-reinforced concrete structures.

In addition, in the above embodiment, as shown in FIG. 1, an example is shown in which the composite beam 10 is joined to the column 50, but the composite beam 10 may be joined to a beam. In this case, the beam may be a member of various structures such as reinforced concrete, steel reinforced concrete, and steel frame.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and one embodiment and various modified examples may be used in appropriate combination, and the present invention may of course be embodied in various forms without departing from the spirit of the present invention.

10, 128 Composite beam 12 Wood beam section 14 Concrete beam section 16 Shear force transmission section 18, 20 Through hole 22, 24 End section 26 Middle section 28 Boundary surface 30 Drift pin (shear force transmission section)
32 Slab X1 Beam width direction (beam width direction of concrete beam section)

Claims (4)

A wooden beam portion having an end portion and a middle portion, the end portion having a beam depth higher than the middle portion, and the end portion having an inverted drop haunch shape ;
A concrete beam section provided on the upper surface of the intermediate section of the wooden beam section;
A shear force transmission portion provided on the boundary surface between the wooden beam portion and the concrete beam portion;
a through hole formed in the concrete beam portion and penetrating the concrete beam portion in a beam width direction ,
A cross section of the intermediate portion in the beam length direction is the same from one end portion to the other end portion,
A composite beam in which the shear force transmission portion is composed of a plurality of drift pins arranged at intervals in the beam length direction, and the drift pins arranged at the ends of the middle portion are arranged more densely in the beam length direction than the drift pins arranged in the middle portion of the middle portion . The composite beam according to claim 1, wherein a slab is provided so as to extend from the upper end of the concrete beam section in the beam width direction of the concrete beam section. The composite beam according to claim 1 or 2, wherein the concrete beam section is made of precast members. A wooden beam section including both ends in a beam length direction and a middle section formed between the both ends adjacent to the both ends, the beam depth of at least one of the ends being higher than the beam depth of the middle section, and the upper surface of at least one of the ends being located higher than the upper surface of the middle section;
A concrete beam section provided on the upper surface of the intermediate section of the wooden beam section;
A shear force transmission portion provided on the boundary surface between the wooden beam portion and the concrete beam portion;
a through hole formed in the concrete beam portion and penetrating the concrete beam portion in a beam width direction ,
A cross section of the intermediate portion in the beam length direction is the same from one end portion to the other end portion,
A composite beam in which the shear force transmission portion is composed of a plurality of drift pins arranged at intervals in the beam length direction, and the drift pins arranged at the ends of the middle portion are arranged more densely in the beam length direction than the drift pins arranged in the middle portion of the middle portion .