JP5313510B2 - Steel pipe bracing buckling method for existing buildings - Google Patents

Description

The present invention relates to seismic reinforcement of an existing building having steel pipe braces, and more particularly to a method of buckling and stiffening without removing or replacing an existing steel pipe brace.

In general, a brace material is effective in its entire cross-section when subjected to a tensile force. However, when subjected to a compressive force, the brace material is buckled according to the slenderness ratio, so that the member yield strength is greatly reduced. For this reason, in the seismic diagnosis of existing buildings, it is necessary to evaluate such as ignoring the compression side brace or reducing it to the stable strength after buckling. However, buckling stiffening of the brace material improves the compressive strength,
It has been confirmed that the yield strength equivalent to that of the brace on the tension side can be obtained, and the buckling stiffening of the brace material is very effective for the seismic reinforcement of existing buildings.

For example, in the case of a K-type brace, as shown in FIG. 1A, when the compression-side brace c buckles due to the seismic force b acting on the beam a, the center portion of the beam is pulled downward and deformed. However, if the brace material is appropriately buckled and stiffened, as shown in FIG. 1B, when the seismic force b acts on the beam a, the brace d on one side has a tensile force and the other brace c. Since a corresponding compressive force acts on the beam a and there is no difference between tension and compression with respect to the beam a, the bending yield mode in which the center portion of the beam is pulled downward is eliminated, and a high horizontal holding strength can be secured.

By the way, a method for buckling and stiffening without removing or replacing a steel pipe brace of an existing building is already known from Patent Document 1. In this prior art, a steel pipe brace is seated by covering the outside of a steel pipe brace of an existing building with a steel pipe having a split structure and filling mortar between the steel pipe and the steel pipe brace in a non-adhering state with the outer surface of the steel pipe brace. It bends and stiffens.

However, this prior art has a problem that if the steel pipe brace has a large width-thickness ratio, the steel pipe brace may be locally buckled, and can only be applied to a steel pipe brace having a small width-thickness ratio.

In addition, a steel pipe brace buckling stiffening of the double steel pipe system that stiffens the local buckling of the steel pipe brace by inserting and arranging another steel pipe inside the steel pipe brace with a clearance secured between the steel pipe brace. Methods are also known.

However, in this prior art, if the steel pipe brace has a large width-thickness ratio, the steel pipe brace may be locally buckled outward, and can be applied only to a steel pipe brace having a small width-thickness ratio. Moreover, it is not possible to insert another steel pipe into the steel pipe brace while leaving the steel pipe brace of the existing building in place, so when buckling stiffening the steel pipe brace of the existing building, remove the existing steel pipe brace. There was a problem that it was necessary to exchange or exchange. For this reason, the adoption of this double steel pipe method was practically limited to new construction.

JP 2006-28901 A

The present invention has been made in view of the above-mentioned problems, and the object is as follows.
It is an object of the present invention to provide a steel pipe brace buckling stiffening method for an existing building that prevents local buckling and total buckling without removing or replacing the existing steel pipe brace.

The technical means taken by the present invention to achieve the above object are as follows. In other words, the steel pipe brace buckling and stiffening method for an existing building according to the first aspect of the present invention provides a hole in a part of the steel pipe brace in the existing building, and a cement-based solidified material is filled into the steel pipe brace from the hole. And
To stiffen local buckling of steel pipe braces, it is made of synthetic resin with grease applied to the outer surface.
After inserting the bag from the inside into the hole of the steel pipe brace is characterized and this <br/> filling the cement solidifying material in the bag.

In addition, as a cement-type solidified material, mortar, concrete, etc. are used, for example. It is desirable to fill the cement-based solidified material in a non-adhering state with the inner surface of the steel pipe brace for the reasons described later.

The invention according to claim 2 is the steel pipe brace buckling stiffening method of the existing building according to claim 1, wherein the steel pipe brace is filled with cement-based solidified material and then buckled outside the steel pipe brace. A steel member for forming a stiffening member is arranged, and the steel members are joined together to form a buckling stiffening member that is not fixed to the steel pipe brace. It is characterized by stiffening.

According to a third aspect of the invention, a steel brace seat屈補Tsuyoshi method existing buildings according to claim 2, the steel member for the seat屈補rigid member formed of a pair of upper and lower U-shaped steel plates And the opening width of the lower U-shaped steel plate is set to fit the opening width of the upper U-shaped steel plate, and the lower U-shaped steel plate opening end is the opening end of the upper U-shaped steel plate. It arrange | positions in the state piled up on the outer side of this, and this overlap part is fillet-welded.

According to invention of Claim 1, even if the steel pipe brace of the existing building is a brace material with a large width-thickness ratio, local buckling of the steel pipe brace is prevented by the cement-based solidified material filled in the steel pipe brace. As a result, it is not necessary to remove or replace the existing steel pipe brace, so that the construction can be rationalized and speeded up.

In particular, if cement-based solidified material is filled in a non-adhering manner with the inner surface of the steel tube brace, it is insulated from the inner surface of the steel tube brace, so this cement-based solidified material does not contribute to compressive force or tensile force. Only useful for bending and stiffening. Therefore, the buckling stiffening does not impair the balance between the tension side brace and the compression side brace, and a steel pipe brace having high deformation performance is constructed.

In addition, according to the first aspect of the present invention, as a method for filling the inside of the steel pipe brace with cement-based solidified material in a non-adhering state with the inner surface of the steel pipe brace, a bag made of a synthetic resin with grease applied to the outer surface is provided. Since it was inserted into the brace and the bag was filled with cement-based solidified material, a double insulation effect by a synthetic resin bag and grease can be expected. The synthetic resin bag with the outer surface coated with grease may have a single structure, but the outer surface of the outer bag may also be inserted by inserting a bag with the outer surface coated with grease into another synthetic resin bag. A double-greased bag with grease applied is preferable in that it can prevent adverse effects (attachment of leaked cement-based solidified material) due to breakage of the bag during insertion into the steel pipe brace.

According to the second aspect of the present invention, a hole is formed in a part of the steel pipe brace in the existing building, and the cemented solidified material is filled into the steel pipe brace from the hole, and then the buckling stiffening is performed outside the steel pipe brace. By arranging steel members for forming members and joining the steel members together, a buckling stiffening member that is not fixed to the steel pipe brace is formed, thereby compensating for the overall buckling of the steel pipe brace. Because it stiffens, in the seismic reinforcement of existing buildings with steel pipe braces, local buckling and overall buckling can be stiffened without removing or replacing the existing steel pipe braces so that they are equivalent to the tension side braces. It is possible to improve the proof stress and rationalize and speed up the construction.

According to the invention described in claim 3 , the steel member for forming the buckling stiffening member is constituted by a pair of upper and lower U-shaped steel plates, and the opening width of the lower U-shaped steel plate is set to the upper U-shape. The opening end of the sheet steel plate is fitted in, and the opening end of the lower U-shaped steel plate is placed on the outside of the opening end of the upper U-shaped steel plate, and this overlapping portion is filled with fillet Since welding is performed, welding work is performed in a downward posture, and workability is good. In addition, by using a U-shaped steel plate assembled by welding three steel plates in a U-shape, the clearance managed between the outer surface of the steel pipe brace and the inner surface of the buckling stiffening member can be managed. It becomes easy.

2 and 3 show an embodiment of the present invention. Reference numeral 1 denotes a steel pipe brace of an existing building. A cement-based solidified material (mortar is used but concrete may be used) 2 filled inside the steel pipe brace 1 in a non-adhering state with the inner surface of the steel pipe brace 1 and a steel pipe brace. 1 is buckled and stiffened inward and outward by a buckling stiffening member 3 disposed so as to surround it. The buckling stiffening member 3 is composed of a steel member for forming a buckling stiffening member (in the illustrated embodiment, a pair of upper and lower U-shaped steel plates 3a and 3b). Although arranged so as to surround, it is not fixed to the steel pipe brace 1. Both ends of the steel pipe brace 1 are treated as non-stiffening sections and are not stiffened.

The buckling stiffening member 3 is attached to the outer surface of the steel pipe brace 1 as shown in FIG. 3, or the lower end abuts against the mounting plate 4 of the steel pipe brace 1 as shown in FIG. The lower end of the buckling stiffening member 3 is brought into contact with the receiving piece 5 so as not to be lowered by its own weight.

The buckling and stiffening method for the steel pipe brace 1 shown in FIGS. 2 and 3 will be described as follows. First, as shown in FIGS. 4A and 4B, a circular hole 6 having an inner diameter capable of injecting cement-based solidified material is provided on the upper surface of the steel pipe brace 1 installed obliquely.

Next, as shown in FIG. 4C, a synthetic resin bag (for example, a bag made of thick polyethylene or the like) 7 in which grease is applied to the outer surface from the hole 6 to the inside of the steel pipe brace 1 is formed. insert. The synthetic resin bag 7 having the outer surface coated with grease may have a single structure, but in the illustrated embodiment, the outer surface coated grease is inserted into another synthetic resin bag, Double-greased bag 7 with grease applied to the outer surface of the outer bag to prevent harmful effects caused by bag breakage (adhesion of leaked cement-based solidified material) when inserted into steel pipe brace 1 Considered to be.

After that, as shown in FIGS. 4D and 4E, the cement-based solidified product 2 is injected into the bag 7 and filled in the steel tube brace 1 in a state insulated by the bag 7 with grease. To do.

After a predetermined strength is developed in the cement-based solidified product 2, the mouth portion of the bag 7 protruding from the steel pipe brace 1 is excised as shown in FIG.

After finishing buckling stiffening on the inside of the steel pipe brace 1 in this way, as shown in FIGS. 5A to 5D, a pair of upper and lower U-shaped steel plates 3a and 3b are formed outside the steel pipe brace 1. The buckling stiffening member 3 made of is arranged to buckle and stiffen the outer side of the steel pipe brace 1. In manufacturing the U-shaped steel plates 3a and 3b, the outer diameter of the steel pipe brace 1 is measured in advance so that a predetermined clearance can be secured between the steel pipe brace 1 and the buckling stiffening member 3. The lower U-shaped steel plate 3
The opening width of b is set to a dimension in which the opening end of the upper U-shaped steel plate 3a is fitted.

The specific construction procedure is as follows. First, as shown in FIGS. 5A and 5B, the upper U-shaped steel plate 3a is placed on the steel pipe brace 1 from the upper surface side.

Thereafter, as shown in FIGS. 5C and 5D, the lower U-shaped steel plate 3b is placed on the steel pipe brace 1 from the lower surface side, and the open end of the lower U-shaped steel plate 3b is placed on the upper side. It arrange | positions in the state piled up on the outer side of the opening end of the U-shaped steel plate 3a, and this state is hold | maintained by a suitable temporary fix | stop means (not shown).

In this state, as shown in FIG. 5E, the above-described buckling stiffening member 3 is formed by performing fillet weld W on the overlapping portions of the upper and lower U-shaped steel plates 3a and 3b. Fillet weld W
May be any of covering arc welding, carbon dioxide semi-automatic welding, etc., but with the opening end of the lower U-shaped steel plate 3b superimposed on the outside of the opening end of the upper U-shaped steel plate 3a. Therefore, fillet welding W is performed in a downward posture, so that sound welding can be easily performed.

According to said structure, even if the steel pipe brace 1 of the existing building is a brace material with a big width-thickness ratio, the local buckling of the steel pipe brace 1 is the cement-type solidified material 2 with which the inside of the steel pipe brace 1 was filled.
The overall buckling of the steel pipe brace 1 is prevented by the buckling stiffening member 3.

The cement-based solidified material 2 filled in the steel pipe brace 1 is not attached to the inner surface of the steel pipe brace and is insulated from the inner surface of the steel pipe brace, so it does not contribute to compressive force or tensile force, Only useful for bending and stiffening. Buckling stiffening member 3 formed outside the steel pipe brace 1
Is not fixed to the steel pipe brace 1 and is insulated from the outer surface of the steel pipe brace.
It does not contribute to compressive force or tensile force, and is useful only for buckling stiffening. Therefore, the buckling stiffening does not impair the balance between the tension side brace and the compression side brace, and a steel pipe brace having high deformation performance is constructed.

In particular, according to the above configuration, the hole 6 is provided in the upper surface of the steel pipe brace 1 in the existing building, and the cement-based solidified material 2 is filled from the hole 6 into the steel pipe brace 1 in a non-adhering state to the inner surface of the steel pipe brace. Then, the local buckling of the steel pipe brace 1 is stiffened, and then a pair of upper and lower U-shaped steel plates 3a, 3b are arranged outside the steel pipe brace 1, and the U-shaped steel plates 3a, 3b are welded to each other. As a result, the buckling stiffening member 3 that is not fixed to the steel pipe brace 1 is formed and the overall buckling of the steel pipe brace 1 is stiffened. Therefore, in the seismic reinforcement of the existing building having the steel pipe brace 1, The steel pipe brace 1 can be buckled and stiffened without removing or replacing the steel pipe brace 1 to improve the yield strength so as to be equivalent to the tension side brace, and the construction can be rationalized and speeded up.

The grease-filled bag 7 for filling the cement-based solidified product 2 with the inner surface of the steel pipe brace in a non-adhering state has a length that extends over the entire length of the steel pipe brace 1, and an upper surface near the upper end of the steel pipe brace 1 as shown in FIG. It is possible to insert the cement-based solidified material 2 into the steel pipe brace 1 through the holes 6 formed at the same time, and to inject a plurality of holes at predetermined intervals on the upper surface of the steel pipe brace 1 as shown in FIG. 6 may be formed, and the greased bag 7 may be inserted and the cement-based solidified material 2 may be injected in order from the lower hole 6.

8A and 8B show another embodiment of the present invention. In this embodiment, as a method of filling the cement-based solidified material 2 in a non-adhering state with the inner surface of the steel pipe brace, the nozzle 8 inserted from the hole 6 formed in the upper surface in the vicinity of the upper end of the steel pipe brace 1 is put inside the steel pipe brace 1. The release agent 9 is sprayed to form an adhesion preventing coating 10 on the inner surface of the steel pipe brace 1, and then the cement-based solidified material 2 is filled into the steel pipe brace 1 through the holes 6.

According to this configuration, the release agent 9 is sprayed inside the steel pipe brace 1 to form the adhesion preventing coating 10 on the inner surface of the steel pipe brace, and then the cement-based solidified material 2 is filled inside the steel pipe brace 1. Therefore, the work with good grease is not necessary because the bag 7 with grease and the operation of pushing it into the steel pipe brace 1 are unnecessary. Since other configurations and operations are the same as those of the previous embodiment, the description thereof is omitted.

9A and 9B show another embodiment of the present invention. In this embodiment, as a method of filling the cement-based solidified material 2 in a non-adhering state with the steel pipe brace inner surface, a predetermined amount of the release agent 9 is poured into the inside of the steel pipe brace 1 from the hole 6 and stored in the bottom of the steel pipe brace, By discharging the cement-based solidified material 2 from the tip opening of the tube 11 with the tip-end opening of the cement-based solidified material casting tube 11 inserted from the hole 6 always positioned below the liquid surface of the release agent 9. The steel pipe brace 1 is characterized in that it is filled with a cement-based solidified product 2.

According to this configuration, a predetermined amount of release agent 9 poured into the inside of the steel pipe brace 1 from the hole 6 is stored in the bottom portion of the steel pipe brace, and the opening of the tube 11 inserted into the steel pipe brace is always placed in the liquid of the release agent 9. Cement-based solidified product 2 from the tip opening of the tube 11 in a state of being positioned below the surface.
Since the cement-based solidified material 2 is filled in the steel pipe brace 1 by discharging the liquid, the liquid level of the release agent 9 is pushed up by the cement-based solidified material 2 as the cement-based solidified material 2 is filled. The adhesion preventing coating 10 is formed on the inner surface of the steel pipe brace simultaneously with the filling of the cement-based solidified product 2. Therefore, the spray nozzle 8 and its insertion / extraction operation are unnecessary, and the workability is good. Other configurations and operations are the same as those in the embodiment of FIG.

In each of the above-described embodiments, the cement-based solidified material 2 filled in the steel pipe brace 1 is not a non-shrink type, but is a normal mortar or an admixture with a large shrinkage (for example, CaCl 2 or the like). ) And using a high shrinkage type mortar with a large water-cement ratio is desirable because it is easy to ensure insulation between the inner surface of the steel pipe brace and the mortar. This is because the insulation between the steel pipe brace and the mortar is ensured even during compression, and the mortar does not contribute to the axial rigidity of the steel pipe brace, so that an effective buckling stiffening effect is maintained.

It is a figure explaining the effect of buckling stiffening in a K type brace. It is a front view which shows embodiment of this invention. It is a vertical front view of the principal part. It is explanatory drawing of the method of buckling and stiffening the inner side of a steel pipe brace. It is explanatory drawing of the method of buckling and stiffening the outer side of a steel pipe brace. It is explanatory drawing of the method of filling a cement-type solidified material with a steel pipe brace inner surface in a non-adhesion state. It is explanatory drawing of the method of filling a cement-type solidified material with a steel pipe brace inner surface in a non-adhesion state. It is explanatory drawing of the method of filling a cement-type solidified material with a steel pipe brace inner surface in a non-adhesion state. It is explanatory drawing of the method of filling a cement-type solidified material with a steel pipe brace inner surface in a non-adhesion state.

DESCRIPTION OF SYMBOLS 1 Steel pipe brace 2 Cement-based solidified material 3 Buckling stiffening member 3a, 3b U-shaped steel plate (steel member for buckling stiffening member formation)
4 Mounting plate 5 Receiving piece 6 Small hole 7 Bag 8 Nozzle 9 Release agent 10 Adhesion prevention coating 11 Tube W Fillet welding a Beam b Seismic force c Compression side brace d Tensile side brace

Claims (3)

In order to stiffen the local buckling of the steel pipe brace by providing a hole in a part of the steel pipe brace in the existing building and filling the inside of the steel pipe brace with cement-based solidified material from the hole , grease is applied to the outer surface.
After the synthetic resin bag coated with is inserted into the steel pipe brace through the hole, the
A steel pipe brace buckling stiffening method for an existing building, which is filled with a solid material . A steel pipe brace seat屈補Tsuyoshi method existing buildings according to claim 1, the interior of the steel pipe brace
Steel member for forming buckling stiffening member outside of steel pipe brace after filling cement-based solidified material
Is fixed to the steel pipe brace by joining the steel members
A method for buckling and stiffening a steel pipe brace of an existing building, comprising forming a non-buckling stiffening member to stiffen the overall buckling of the steel pipe brace. The steel pipe brace buckling and stiffening method for an existing building according to claim 2 , wherein the buckling stiffening member shape is used.
The steel member is composed of a pair of upper and lower U-shaped steel plates, and the opening width of the lower U-shaped steel plate is set to the upper side.
The size of the open end of the U-shaped steel plate is set to fit, and the open end of the lower U-shaped steel plate is the upper U-shaped steel plate.
A method for buckling and stiffening a steel pipe brace of an existing building, characterized in that it is arranged in a state where it is overlapped on the outside of the opening end of the steel plate, and the overlap portion is welded to the fillet .

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