JP3222114B2 - Plastic hinge method for pile head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of plastically hinged pile heads in seismic isolation and seismic isolation of buildings and the like.

[0002]

2. Description of the Related Art In order to make a building or the like have a seismic isolation / seismic isolation structure, it has been studied to provide a damper 2 on a building frame 1 as shown in FIG. Or an oil damper or an active air damper is used. When such a damper 2 is used to suppress the sliding, a sliding layer is provided between the building frame 1 and the pile 3 or the head of the pile 3 is used. The part must be a plastic hinge 19.

As described above, in order to make the head of the pile 3 plastically hinged, as shown in FIGS. 9 and 10, a joint (foundation footing) 7 in the building frame 1 and the head of the pile 3 are used. The sliding mechanism 5 is disposed on the rim, and a breakage site 6 is formed corresponding to the sliding mechanism 5. The destruction site 6 is replaced with destruction sites 6a, 6b, 6
FIG. 11 shows an example of the restoration characteristics in the case where the device is installed in a plurality of stages and c.

In order to realize the plastic hinge of the pile head as shown in FIG. 9 and FIG. 10, it is conceivable to use a rolling mechanism such as a bearing for the sliding mechanism 5. It is conceivable that small pillars such as concrete are formed on 6a, 6b and 6c so as to hang down, and these are radially arranged around the head of the pile 3 to serve as obstacles for sliding. It is very difficult to add such a mechanism later to the existing building, and even in the case of a new building, the structure is relatively complicated and the construction is troublesome.

[0005] The inventors of the present invention have previously disclosed in Japanese Patent Application No. 8-289581 (JP-A-10-131205) FIGS.
The inventors applied for a method and structure for plastically hinged pile heads as shown in FIG. 14 and obtained a patent as Patent No. 2858113.

[0006] In the figure, reference numeral 3 denotes a pile, the head of which is connected to a foundation underground beam 4 of the building frame 1 by a joint (foundation footing) 7. Reference numeral 8 denotes a pile main bar constituting the pile 3, and 9 denotes a hoop bar.

A work space 10 is secured by excavating around the head of the pile 3 at the foundation, and as shown in FIGS.
The outer peripheral portion of the head immediately below the joint 7 is shaved to remove the outer peripheral concrete, the main pile bars 8 and the hoop bars 9.

After the peripheral concrete, the pile main reinforcement 8 and the hoop reinforcement 9 have been removed from the head of the pile 3 immediately below the joint 7, the non-reinforced concrete at the center is removed.
A reduced diameter portion by 11 and a concave portion 12 outside thereof are formed,
A precast concrete member 13 serving as a sliding support member was arranged in the recess 12 in a necklace shape.

The precast concrete member 13 is a divided block body which forms a ring body by combination, forms a boxed portion 14, where the end of a steel bar or PC steel bar 15 is exposed, and a nut 16 is formed. Fit and fasten.

Further, the precast concrete member
13 has a steel plate 17 for edging at the top end,
When the non-reinforced concrete 11 was set so as to surround it, the gap between the members of the pile 3 was filled with mortar 18 or the like.

The sliding support member may be formed of steel instead of the precast concrete member 13. In the case of steel, although not shown, the sliding support member is connected to a bolt / nut and a joint plate. What is necessary is just to fasten with a ring body and to arrange | position in a necklace shape.

In the head of the pile 3, the concrete at the outer periphery just below the joint with the building frame 1 and the non-reinforced concrete 11 obtained by shaving off the pile main bar 8 and the hoop bar 9 are destroyed together with the pile supporting force. A precast concrete member 13 having a steel plate 17 for edging at the top end or a sliding support member made of a steel material serves as a support member and a sliding mechanism.

[0013] In order to provide such a fractured portion, it is only necessary to cut off the concrete and the pile main bar and the hoop bar, and to provide the sliding mechanism, the precast concrete member or the steel material is shackled after being cut off. It can be easily applied to existing buildings and the like because it only needs to be arranged in a shape.

In this way, when a horizontal fluctuation such as an earthquake is received, the steel plate 17 for edge cutting slides and the non-arranged concrete portion 11 is sheared, but the precast concrete member 13 on the outer peripheral portion is sound. And support the axial force.

[0015]

[Problems to be solved by the invention]
No. 289581 (Japanese Unexamined Patent Publication No. 10-131205) discloses a method and a structure for plastically hinged pile heads. Although the reinforced concrete 11 is used as the fracture site having the pile supporting force, it is not clear how the fracture occurs, and there is a possibility that the expected pile supporting force cannot be obtained.

As a result, a steel plate for edge cutting is provided on the top end.
The load on the precast concrete member 13 or the sliding support member made of steel provided with 17 is too large, and a sufficient sliding effect cannot be obtained.

An object of the present invention is to solve the disadvantages of the conventional example, to realize the structure easily and inexpensively, to easily apply to existing buildings, etc., to obtain a stable supporting force, and to improve the sliding effect. An object of the present invention is to provide a method for plastically hinged a head.

[0018]

According to the present invention, in order to achieve the above object, concrete, a pile main bar, and a hoop bar of an outer peripheral portion immediately below a joint with a building frame are removed from a pile head. The existing concrete part is slightly strengthened around the top and bottom to improve the compressive strength by strengthening the periphery.Furthermore, a precast concrete member or steel member in which a metal plate is arranged at the top end in the empty space formed by the shaving The gist of arranging the sliding support member in the form of a necklace with respect to the reinforced existing concrete portion and the reinforcement applied around the existing concrete portion are to attach a reinforcing member made of a steel pipe or a reinforcing fiber sheet. .

According to the first aspect of the present invention, in the head of the pile, the concrete at the outer peripheral portion immediately below the joint with the building frame and the existing concrete portion obtained by shaving off the pile main bar and the hoop bar are supported by the pile. It becomes a destruction site that combines power,
A precast concrete member with a metal plate for edging at the top end or a sliding support member made of steel is used as a bearing member and a sliding mechanism, but the existing concrete portion is slightly reinforced and reinforced around the periphery to compressive strength As it improves the shear failure, the fracture part can be limited to the upper and lower parts, the upper axial force is supported by the existing existing concrete part in the center and the sliding support member, and a stable supporting capacity is obtained, The central existing concrete portion cooperates with a precast concrete member or a sliding support member made of steel material to exhibit a function as a sliding member, and an efficient sliding effect is obtained.

Further, in order to provide such a fracture site, concrete, a pile main bar and a hoop bar are cut off, and
The remaining existing concrete part only needs to be reinforced around the periphery, leaving a little up and down to improve the compressive strength,
In order to provide a sliding mechanism, it is only necessary to arrange a precast concrete member or a steel material in a shape of a neck after shaving, so that it can be easily applied to an existing building or the like.

According to the second aspect of the present invention, in addition to the above-mentioned functions, the existing concrete portion is slightly and slightly reinforced so as to be reinforced around and improve the compressive strength in a simple and reliable manner. Yes, it can be realized only by attaching a reinforcing member made of a steel pipe or a reinforcing fiber sheet, and the length of the upper and lower portions to be left can be easily and reliably adjusted.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 are side views of respective steps showing a first embodiment of a plastic hinge forming method for a pile head according to the present invention, and FIGS. 5 and 6 are plan views of the same.

In FIG. 1, reference numeral 3 denotes a pile, the head of which is connected to a foundation underground beam 4 of the building frame 1 by a joint (foundation footing) 7. Reference numeral 8 denotes a pile main bar constituting the pile 3, and 9 denotes a hoop bar. The base portion is dug around the head of the pile 3 to secure a work space 10, and as shown in FIGS. As with the conventional example, the outer peripheral portion immediately below the joining portion 7 is shaved to remove the outer peripheral concrete, the pile main bar 8 and the hoop bar 9.

In this way, after the outer peripheral concrete, the pile main reinforcement 8 and the hoop reinforcement 9 have been removed from the head of the pile 3 immediately below the joint 7, the diameter of the central part is reduced by the non-reinforced concrete. The existing concrete portion 20 and the concave portion 12 outside the existing concrete portion 20 are formed.

Next, as shown in FIG. 3, a carbon fiber sheet 21 or an aramid fiber sheet and other reinforcing fiber sheets are pasted as reinforcing members around the existing concrete part 20 while leaving the upper and lower portions slightly (about 1 to 2 cm). I do.

As described above, the carbon fiber sheet is used as the reinforcing member.
By pasting 21 or the like, the existing concrete part 20 can improve the compressive strength while slightly leaving the upper and lower α and β.

Further, a precast concrete member 13 as a sliding support member is arranged in the concave portion 12 in a necklace shape. As shown in FIG. 6, a precast concrete member
Reference numeral 13 denotes a divided block body that constitutes a ring body by combination, and forms a box blank portion 14, in which an end of a steel bar or a PC steel bar 15 is exposed, and a nut 16 is fitted and fastened.

Also, the precast concrete member
13 has a steel plate 17 for edging at the top end,
As shown in FIG. 4, the gap between the members of the pile 3 was filled with mortar 18 or the like when it was set so as to surround the existing concrete portion 20.

In this way, when a horizontal movement such as an earthquake occurs, the steel plate 17 for edge cutting slides, and the existing concrete portion 20 has upper and lower α and β where the carbon fiber sheet 21 and the like are not attached. Destroy only the part.

The existing concrete portion 20 is sound except for the upper and lower broken portions, and supports the axial force.

FIG. 7 shows a second embodiment of the present invention, in which a steel pipe 22 is used as a reinforcing member provided around the existing concrete portion 20. The steel pipe 22 is formed around the existing concrete part 20 as a tubular member by using a curved steel plate as a divided member and being connected to each other by welding, bolting, or the like. An adhesive may be interposed between the steel pipe 22 and the existing concrete portion 20.

By arranging the steel pipe 22 as a reinforcing member in this way, the compressive strength can be improved while leaving the existing concrete portion 20 slightly up and down.

In the above-described embodiment, a precast concrete member is used as the sliding support member. However, as a third embodiment, this can be formed of steel. In the case of a steel material, although not shown, it may be connected to a bolt / nut with a joining plate, fastened with a ring, and arranged in a necklace shape.

Further, in the case of a steel material, if the flange or the like is used as it is, the top end can be made a smooth surface, so that there is no need to dispose a steel plate for edging such as a precast concrete member.

[0035]

As described above, the method for plastically hinged pile heads according to the present invention can be realized easily and inexpensively, can be easily applied to existing buildings, etc., and can improve the shear fracture to reduce the fracture portion. Since it can be limited, a stable supporting force is obtained, and the sliding effect is improved.

[Brief description of the drawings]

FIG. 1 is a side view of a first step showing a first embodiment of a plastic hinge forming method for a pile head according to the present invention.

FIG. 2 is a side view of a second step showing the first embodiment of the method of plasticizing a pile head according to the present invention.

FIG. 3 is a side view of a third step showing the first embodiment of the plastic hinge forming method for a pile head according to the present invention.

FIG. 4 is a side view of a fourth step showing the first embodiment of the plastic hinge forming method for the pile head according to the present invention.

FIG. 5 is a cross-sectional plan view of a second step showing the first embodiment of the plastic hinge forming method for the pile head according to the present invention.

FIG. 6 is a cross-sectional plan view of a fourth step showing the first embodiment of the plastic hinge forming method for a pile head according to the present invention.

FIG. 7 is a side view of a third step showing a second embodiment of the plastic hinge method for a pile head according to the present invention.

FIG. 8 is an explanatory diagram showing an example in which a building or the like has a seismic isolation / seismic isolation structure.

FIG. 9 is a longitudinal sectional side view showing a conventional example of plastic hinge formation of a pile head.

FIG. 10 is a cross-sectional bottom view showing a conventional example of plastic hinge formation of a pile head.

FIG. 11 is a correlation diagram of force and deformation showing the restoring characteristic of the conventional plastic hinge of the pile head.

FIG. 12 is a side view showing a post-process of a conventional example.

FIG. 13 is a plan view showing a pre-process of a conventional example.

FIG. 14 is a plan view showing a post-process of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Building frame 2 ... Damper 3 ... Pile 4 ... Foundation beam 5 ... Sliding mechanism 6, 6a, 6b,
6c: Fracture site 7 ... Joint 8: Pile main bar 9 ... Hoop bar 10 ... Work space 11 ... Unreinforced concrete 12 ... Recess 13 ... Precast concrete member 14 ... Boxless portion 15 ... Steel bar or PC steel bar 16 ... Nut 17 ... steel plate 18 ... mortar 19 ... plastic hinge 20 ... existing concrete part 21 ... carbon fiber sheet 22 ... steel pipe

Claims (2)

(57) [Claims] [Claim 1] In the head of a pile, the concrete at the outer peripheral portion immediately below the joint with the building frame, the main reinforcement of the pile and the hoop reinforcement are scraped off, and the remaining existing concrete portion is reinforced around the periphery while slightly leaving the upper and lower portions. To improve the compressive strength, and furthermore, to a precast concrete member in which a metal plate is arranged at the top end in a space formed by the above-mentioned cutting and a sliding support member made of steel to reinforce an existing concrete portion which is shackled. A method of plastically hinged pile heads, comprising: 2. The method according to claim 1, wherein the reinforcement applied around the existing concrete portion includes attaching a reinforcing member made of a steel pipe or a reinforcing fiber sheet.