JP5483666B2 - building - Google Patents

Description

  The present invention relates to a building having a column structure that suppresses column buckling.

  The column is designed in cross-sectional area and member length so that it does not collapse due to bending buckling caused by the load applied to the column.

  For this reason, for example, in an existing building, when a beam or slab joined to an existing column is removed and the structure is changed to a blow-off structure, the length of the member is increased by removing the beam or slab, and the load applied to the column The column may buckle even if the value decreases.

  In order to prevent the existing column from buckling in such a situation, it is necessary to increase the buckling strength of the existing column. For this purpose, a method of increasing the cross-sectional area of the existing column is effective, but it is difficult in terms of construction to increase the cross-sectional area of the existing column.

  On the other hand, in existing buildings, there is a high demand for removing beams and slabs and changing them to a blow-by structure, and there is a need for a technology that suppresses column buckling without causing buckling even if existing columns are used as they are. ing.

As a technique for increasing the strength of a column without changing the cross-sectional area of the column, a structure in which the periphery of the column is surrounded by a steel pipe and a space is provided between the column and the steel pipe has been proposed (Patent Document 1).
However, in Patent Document 1, as shown in FIG. 9, in the event of a fire, the periphery of the pillar is surrounded by a steel pipe in order to slow down the strength of the pillar due to heat.

  That is, the periphery of the pillar (inner steel member 2) is surrounded by the outer steel member 1, and a hollow portion 3 is formed between the inner steel member 2 and the outer steel member 1 instead of applying a fireproof coating to the inner steel member 2. Yes. At this time, the upper and lower ends of the outer steel member 1 are connected to the inner steel member 2 by the diaphragm 4 of the joint, and share the vertical load applied to the diaphragm 4 with the inner steel member 2.

  For this reason, the vertical load applied to the diaphragm 4 is applied to each of the inner steel member 2 and the outer steel member 1. When the vertical load increases and exceeds the allowable buckling value of the inner steel member 2 and the outer steel member 1, both the inner steel member 2 and the outer steel member 1 start to buckle.

That is, in the configuration of Patent Document 1, the strength of the column (inner steel member 2) can be increased to some extent, but the buckling of the column cannot be suppressed.
JP-A-5-302399

  In view of the above-described facts, the present invention aims to suppress column buckling.

The building according to claim 1 is connected to a column whose length is increased by removing a beam or a slab in an intermediate layer, and an upper beam and a lower beam or a slab on a beam. A steel pipe that surrounds and surrounds the lower surface of the upper beam, and is arranged with a predetermined clearance from the lower surface of the upper beam so that the center and both ends of the column abut against the inner peripheral surface when bending deformation occurs in the column. It is characterized by having.

According to the first aspect of the present invention, when a bending buckling deformation occurs in the column due to a load applied to the column whose member length is increased by removing the intermediate beam or slab from the upper beam, the column The outer peripheries of the central part and both end parts of the steel plate contact the inner perimeter of the surrounding steel pipe, and further deformation of the column is restricted by the rigidity and strength of the steel pipe. As a result, the buckling of the column whose member length is increased is suppressed.

In addition, the upper end of the steel pipe has a predetermined gap with the lower surface of the upper beam, and the load of the upper beam is not directly applied to the steel pipe but is transmitted to the column through the lower slab or the lower beam. .
Thus, buckling of a pillar can be suppressed, without a steel pipe buckling because a steel pipe has an edge with the upper beam cut.

The building according to the invention of claim 2 surrounds the column with a predetermined gap between the column to which the beam is connected and the upper beam and the lower beam or the slab on the beam, A steel pipe disposed at a predetermined gap from the lower surface of the upper beam and having a central portion and both end portions of the column abutting against an inner peripheral surface when bending deformation occurs in the column; A beam support portion for supporting an intermediate beam provided between the lower beam and the lower beam or the slab on the beam, and a lower support portion of the steel pipe provided on the lower beam or the slab on the beam. And a steel pipe support member.

According to invention of Claim 2, the steel pipe is supporting the intermediate | middle layer beam by the beam support part, and the steel pipe support member is supporting the lower end part of the steel pipe.
Thereby, the load transmitted from the intermediate layer beam is transmitted to the column through the steel pipe, the steel pipe support member, and the lower slab or the lower beam.

According to a third aspect of the present invention, in the building according to the first or second aspect, the steel pipe is a divided member obtained by dividing the steel pipe in a circumferential direction, and is joined by surrounding the column from the outside.
According to invention of Claim 3, the steel pipe is made into the division member divided | segmented into the circumferential direction. With this divided member, buckling can be reinforced by surrounding and joining the pillars of the existing building.

Invention of Claim 4 is the building of any one of Claims 1-3 , The said pillar is a pillar of the existing building, It is characterized by the above-mentioned.
Thereby, the pillar of an existing building can be enclosed and joined from the outside with a division member.

  Since the present invention is configured as described above, it is possible to suppress column buckling.

(First embodiment)
The column structure 8 according to the first embodiment includes a column 10 and a steel pipe 16 surrounding the column 10.
As shown in FIG. 1, the column 10 supports the upper beam 12 and the lower beam 15 (not shown), and the beam 12 and the beam 15 are provided with an upper slab 13 and a lower slab 14, respectively. ing.

  Before the reconstruction of the building 27 shown in FIG. 1, intermediate layer beams 48 and 50 were provided between the beam 12 and the slab 14, and the intermediate layer beams 48 and 50 were supported by the pillar 10. In addition, the intermediate layer beams 48 and 50 are provided with slabs 49 and 51 to form a three-layer structure.

  The slabs 49 and 51 and the intermediate layer beams 48 and 50 are removed by renovation, and a blow-off structure is formed. For this reason, the member length of the pillar 10 is long, and the height of three layers is the member length.

The column 10 is made of a section steel or CFT (concrete-filled column) having a widely used cross-sectional shape regardless of the cross-sectional shape.
The steel pipe 16 has a box-shaped cross-sectional shape, and surrounds the periphery of the column 10 with a predetermined gap d from the surface of the column 10.

  In addition, the connection member which connects the pillar 10 and the steel pipe 16 is not attached to the clearance gap between the pillar 10 and the steel pipe 16. Thereby, the steel pipe 16 can move the distance of the gap d in the horizontal direction in a state of surrounding the column 10.

  Further, the steel pipe 16 has rigidity and strength capable of suppressing horizontal deformation of the column 10 due to buckling, and between the upper surface of the slab 14 and the height at which a predetermined gap h is opened from the lower surface of the beam 12. It is assumed that the length of the crossing member. The steel pipe 16 can move the distance h in the vertical direction while surrounding the column 10.

  Thus, as shown in FIG. 2, when the column 10 is bent and deformed by the axial force N applied to the column 10, the outer periphery 10 a of the column 10 is surrounded by the central portion and both end portions of the inner periphery 16 a of the steel pipe 16 surrounding the periphery. Hit three places. Since the steel pipe 16 has rigidity and strength that can suppress deformation in the horizontal direction of the column 10, the column 10 is restrained by the steel pipe 16, so that the column 10 does not buckle.

The steel pipe 16 is not directly subjected to the load of the upper beam 12 due to the gap h opened at the upper end of the steel pipe 16 and the lower surface of the upper beam 12, and the steel pipe 16 is deformed by the axial force N. Absent.
As described above, the pillar structure 8 can suppress buckling of the pillar 10 and can remodel an existing building into a high-level skeleton structure.

  In the above, an example in which the intermediate layer beams 48 and 50 and the slabs 49 and 51 in the existing building are removed has been described. However, the present invention is not limited to the two layers, and the column is in units of the member length of the column 10. The structure 8 may be used.

Here, a method of surrounding the column 10 with the steel pipe 16 will be described.
As shown in FIG. 3A, first, the steel pipe 16 is a divided member of a first steel pipe 56 and a second steel pipe 57 that are divided in advance in the circumferential direction. By dividing | segmenting into the 1st steel pipe 56 and the 2nd steel pipe 57, the pillar 10 of an existing building can be enclosed from the outside, and it can join in the enclosed state.
Each of the first steel pipe 56 and the second steel pipe 57 is formed in an L shape with dimensions such that the length of each side is larger than the width D of the column 10 and a predetermined gap d can be secured around the column 10. .

Next, the pillar 10 of the existing building is surrounded from the outside by the first steel pipe 56 and the second steel pipe 57, and the joint portion is welded.
That is, the end portion 56T of the first steel pipe 56 and the side surface 57S of the second steel pipe 57, and the side surface 56S of the first steel pipe 56 and the end portion 57T of the second steel pipe 57 are abutted and welded.
Thereby, the pillar 10 of the existing building can be surrounded by the steel pipe 16.

  The dividing method is not limited to FIG. 3A. As shown in FIG. 3B, the first steel pipe 65 surrounding the three side surfaces of the column 10 and one side surface of the column 10 are arranged. You may divide | segment into two of the 2nd steel pipe 66 to surround. Although not shown, it can be divided into four flat plate portions corresponding to the four side surfaces of the pillar 10.

  In any of the divisions, the pillar 10 is surrounded by the dividing member, and after the pillar 10 is enclosed, the steel pipe 16 is joined by the joint portion. Thereby, the buckling of the pillar 10 of an existing building can be suppressed with the joined steel pipe 16.

  In addition, although the steel pipe 16 demonstrated above was demonstrated as a box-shaped cross-sectional shape, it is not limited to a box shape, What is necessary is just to select according to the cross-sectional shape of the pillar 10. FIG. For example, when the cross-sectional shape of the column 10 is circular, a steel pipe having a circular cross-sectional shape is preferable.

(Second Embodiment)
Contrary to the first embodiment, the column structure 28 according to the second embodiment is a column structure in the case where an existing building with a blow-off structure is remodeled and an intermediate layer beam is added.

As shown in FIG. 4, the column structure 28 includes a column 10 and a steel pipe 26 surrounding the column 10. Descriptions of parts common to the first embodiment are omitted.
The column 10 has a length of three layers, and supports the upper beam 12 and the lower beam 15 (not shown). The beams 12 and 15 are provided with slabs 13 and 14, respectively.

  Further, intermediate layer beams 18 and 20 are provided between the upper beam 12 and the lower slab 14, and the intermediate layer beams 18 and 20 are provided with slabs 17 and 19, respectively.

  The steel pipe 26 has a box-like cross-sectional shape, and surrounds the periphery of the column 10 with a predetermined gap d. Further, the lower end portion of the steel pipe 26 is supported by a support piece 24 provided on the upper surface of the slab 14, and has a member length up to a height at which a predetermined gap h is opened from the lower surface of the beam 12.

  The support piece 24 is configured by dividing a rectangular frame, and is disposed on the upper surface of the slab 14 so as to surround the column 10 from both sides of the column 10.

The steel pipe 26 has an axial force that supports the intermediate layer beams 18 and 20, and the thickness of the steel pipe 26 is increased at a predetermined height in the outer circumferential direction at the joint portion of the steel pipe 26 and the intermediate layer beams 18 and 20. Thickening portions 21 and 22 are provided.
The thickened portion 21 is joined to the end portion of the intermediate layer beam 18, and the thickened portion 22 is joined to the end portion of the intermediate layer beam 20.

  As shown in FIG. 5, the thickened portion 22 is formed of a cylinder having a length L, the inner diameter of which is the same as the inner diameter of the steel pipe 26, and the wall thickness is thicker than that of the steel pipe 26. The length L of the thickened portion 22 is larger than the total thickness W of the intermediate layer beam 20 and the thickness of the slab 19, and the bonding strength with the intermediate layer beam 20 is ensured.

Note that both ends of the thickened portion 22 are joined to the end portion of the steel pipe 26 having a length of one floor by butt welding.
Next, the thickened portion 22 and the intermediate layer beam 20 are joined by abutting the end portion of the intermediate layer beam 20 on the outer peripheral surface of the thickened portion 22 and joining by welding (abutting portion P). Alternatively, using the angle member 60, the thickened portion 22 and the intermediate layer beam 20 are bolted (joined portion Q).

Thereby, the intermediate layer beams 18 and 20 can be supported by the steel pipe 26.
Thereby, the load of the intermediate layer beams 18 and 20 is transmitted to the column 10 through the steel pipe 26, the support piece 24, the slab 14, and the beam 15.

  The support piece 24 may be directly fixed to the side surface of the column 10. Thereby, the lower end of the steel pipe 26 is supported on the upper surface of the support piece 24, and the support piece 24 can transmit the load directly to the column 10 without passing through the slab 14 and the beam 15.

  As described above, the column structure 28 supports the load of the intermediate layer beams 18 and 20 added by the renovation by the steel pipe 26, and does not apply a new load to the column 10. Thereby, the buckling does not occur in the column 10, and the intermediate layer beams 18 and 20 can be added to the building designed as an atrium structure.

Next, the confirmation result of the load deformation characteristics of the column structure 28 will be described.
As shown in FIG. 6, the load deformation characteristic test apparatus 30 has the column structure 28 according to the second embodiment disposed at the center.

The column 10 has a lower portion fixed to the lower support portion 38 of the test apparatus 30 and an upper portion fixed to the upper support portion 36.
One end of the intermediate layer beams 18, 20 is joined to the thickened portions 21, 22 of the steel pipe 26, and the other end of the intermediate layer beams 18, 20 is attached to intermediate support columns 34 provided on both sides of the column structure 28. ing. In addition, the slab is not provided in the intermediate layer beams 18 and 20.

  The upper end of the intermediate support column 34 and the upper end of the upper support portion 36 are connected by a load transmitting portion 33. The end of the load transmitting portion 33 and the upper end of the intermediate support column 34 are the first pins 40, and the lower end of the support column 34 and the foundation support 39 provided on the installation surface are the second pins 42, The ends of the layer beams 18 and 20 are joined by a third pin 44 so as to be rotatable.

  A load adding portion 32 is attached to the upper portion of the load transmitting portion 33, and a load is applied to the load transmitting portion 33 by the load adding portion 32. The upper support portion 36 deforms the upper portion of the column according to the applied load in a state where the column 10 is fixed.

Specifically, the load applying unit 32 applies the horizontal force Q in a state where the axial force N is applied to the column 10.
The addition of the horizontal force Q is performed by moving the load adding portion 32 in the horizontal direction through the load transmitting portion 33, for example, assuming that the displacement in the right direction is + and the displacement in the left direction is −. At this time, the lower support portion 38 is fixed to the installation surface and does not move. Thereby, displacement arises between the lower support part 38 and the upper support part 36, and the pillar 10 deform | transforms with the deformation angle (theta).

  At this time, the intermediate support column 34 is connected in the same manner as the column 10 because the upper end of the intermediate support column 34 is connected to the first pin 40 and the lower end is connected to the second pin 42. Along with this, the intermediate layer beams 18 and 20 also move to the left and right in proportion to the distance in the height direction, and the load deformation characteristics assuming an actual earthquake can be confirmed.

The deformation angle θ is measured by a displacement meter attached to the surface of the steel pipe 26.
Next, test results will be described. As an example, a test result when the axial force ratio (N / Q) is 0.6 is shown in FIG. In FIG. 7, the horizontal axis R is the deformation angle θ (1/1000 rad), and the vertical axis Q is the horizontal force (KN).

  As shown in FIG. 7, the deformation angle θ increases linearly in proportion to the applied horizontal force Q, and the horizontal force Q changes in a state where the column 10 receives axial force N without buckling. You can see that it is following.

  In addition, the axial force N is a magnitude | size which the pillar 10 buckles, and the pillar 10 in case the steel pipe 16 is not provided buckles in the step which only applied the axial force N without applying the horizontal force Q.

  Although illustration is omitted, even if the intermediate layer beams 18 and 20 are not provided, the deformation angle θ increases in proportion to the applied horizontal force Q in a straight line, the column 10 is not buckled, and the horizontal force It is confirmed that the change in Q is followed.

(Third embodiment)
The column structure 46 according to the third embodiment is configured to support the intermediate layer beams 18 and 20 with a diaphragm provided in the steel pipe 52 instead of the thickened portions 21 and 22 described in the second embodiment. is there. Only differences from the second embodiment will be described.

As illustrated in FIG. 8, the column structure 46 according to the third embodiment includes a column 10 and a steel pipe 52 that surrounds the column 10.
The steel pipe 52 has a box shape and surrounds the pillar 10 with a predetermined gap d from the surface of the pillar 10. A diaphragm 54 is attached to a joint portion between the outer peripheral surface of the steel pipe 52 and the intermediate layer beam 20.

  The diaphragm 54 is an H-shaped steel having the same structure as the intermediate layer beam 20 and having a trapezoidal flange. The flange width on the side to be joined to the steel pipe 52 is larger than the width D of the steel pipe 52. It is formed with the same dimension as the flange width with the intermediate layer beam 20.

The diaphragm 54 extends from the four side surfaces of the steel pipe 52 toward the intermediate layer beam 20 with a member length S.
The end of the diaphragm 54 is welded to the surface of the steel pipe 52 on the wide flange width side, and the portion of the steel pipe 52 that is larger than the width D is joined at the ends of the adjacent diaphragms 54.

  The end of the diaphragm 54 on the side with the narrow flange width is almost abutted with the end of the intermediate beam 20 with a gap, and in the abutted state, the webs are bolted together using the splice plate 62, The flanges are bolted together using a splice plate 64.

  Thereby, the load transmitted from the intermediate layer beam 20 is transmitted to the steel pipe 52 through the diaphragm, and from the steel pipe 52 to the column 10 through the support piece 24 (see FIG. 4) and the lower slab 14 or the lower beam 15. Reportedly.

The joints of the intermediate layer beam 18 and the steel pipe 52 have the same configuration.
Further, the upper slab 13 is supported by the beam 12 and the lower slab 14 is supported by the beam 15, but the configuration of only the beams 12 and 15 may be provided without providing the slabs 13 and 14. Moreover, the slab structure without a beam may be sufficient.

It is a figure showing the basic composition of the pillar structure concerning a 1st embodiment of the present invention. It is a figure which shows the suppression principle of the buckling of the column structure which concerns on the 1st Embodiment of this invention. It is a figure which shows the basic composition of the division | segmentation steel pipe structure which concerns on the 1st Embodiment of this invention. It is a figure which shows the basic composition of the pillar structure which concerns on the 2nd Embodiment of this invention. It is a figure which shows the detail of the thickening part of the column structure which concerns on the 2nd Embodiment of this invention. It is a figure which shows the performance verification apparatus of the column structure which concerns on the 2nd Embodiment of this invention. It is a figure which shows the performance verification result of the column structure which concerns on the 2nd Embodiment of this invention. It is a figure which shows the detail of the diaphragm of the column structure which concerns on the 3rd Embodiment of this invention. It is a figure which shows the basic composition of the column structure of a prior art example.

Explanation of symbols

8 pillar structure (first embodiment)
10 pillars 12 beams (above)
13 Slab (upper)
14 Slab (downward)
15 Beam (downward)
16 Steel pipe (first embodiment)
17 Slab (middle layer)
18 Beam (middle layer)
19 Slab (middle layer)
20 Beam (middle layer)
21 Speed governor (thickening part)
22 Speed governor (thickening part)
24 Support piece (steel pipe support member)
26 Steel pipe (second embodiment)
28 Column structure (second embodiment)
46 Column structure (third embodiment)
56 1st steel pipe (split steel pipe)
57 Second steel pipe (split steel pipe)
d Predetermined gap h Predetermined gap

Claims (4)

Columns with longer member lengths by removing intermediate layer beams and slabs ,
The column located between the upper beam and the lower beam or the slab on the beam is surrounded by a predetermined gap and is arranged with a predetermined gap from the lower surface of the upper beam, and is bent and deformed to the column. A steel pipe in which the central part and both end parts of the pillar are in contact with the inner peripheral surface when
Having a building. A column to which the beam is connected;
The column located between the upper beam and the lower beam or the slab on the beam is surrounded by a predetermined gap and is arranged with a predetermined gap from the lower surface of the upper beam, and is bent and deformed to the column. A steel pipe in which the central part and both end parts of the pillar are in contact with the inner peripheral surface when
A beam support provided on the steel pipe and supporting an intermediate beam provided between the upper beam and the lower beam or a slab on the beam;
A steel pipe support member provided on the lower beam or a slab on the beam, and supporting a lower end of the steel pipe;
Having a building.   The building according to claim 1 or 2, wherein the steel pipe is a divided member obtained by dividing the steel pipe in a circumferential direction, and is joined by surrounding the column from the outside.   The building according to claim 1, wherein the pillar is a pillar of an existing building.

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