JP3418677B2 - Joint structure of steel pipe pile and footing - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure between a steel pipe pile and footing concrete.

[0002]

2. Description of the Related Art A conventional pile-footing joint has a structure in which a lower portion of a rebar cage is inserted into a hollow portion of a pile head and an upper portion of the rebar cage is inserted into a footing. It has been implemented.

By the way, in this structure, when the axial force and horizontal force acting on the pile become large, the reinforcing reinforcing bars are densely arranged, which makes it difficult to process and construct them. Furthermore, in order to ensure cross-sectional performance, it is necessary to weld reinforcing reinforcing bars to the head of the pile and install it so as to project above the head of the pile.

As another structure, in the joint structure in which the pile head is embedded in the footing to the extent of the pile diameter, the bar arrangement at the bottom end of the footing becomes dense and workability is poor. Since the pile head and footing are rigidly connected, it is unclear where to break the footing, the pile head, or the middle part of the pile against external force caused by a large earthquake.

Further, when the axial force acting on the pile is large, it is necessary to increase the footing height in order to resist the shearing force, which inevitably increases the size of the footing.

The present invention was created and created in order to solve the above conventional problems.

[0007]

According to the present invention, a joint steel pipe lower portion is inserted into a hollow portion of a steel pipe pile head and fixed by filling mortar inside the joint steel pipe and in the gap between the joint steel pipe and the steel pipe pile. The upper part of the joint steel pipe protruding from the pile head is anchored in the footing concrete above the pile head to make the deformation performance of the joint between the pile head and footing large, and there are many on the inner surface of the pile and the outer surface of the joint steel pipe. The projection is provided.

[0008]

EXAMPLE In the embodiment shown in FIG. 1, the lower portion of the joint steel pipe 2 which is a joint fitting is inserted into the joint steel pipe 2 driven into the ground and into the hollow portion of the joint steel pipe 2 and the head of the steel pipe pile 1. The mortars 3 such as interstitial concrete of the joint steel pipe 2 and the joint steel pipe 2 and the steel pipe pile 1 are fixed by being filled. Concrete of the footing 4 is laid on the upper portion of the steel pipe pile 1 so that the joint steel pipe 2 protruding from the head of the steel pipe pile 1 is buried with reinforcing bars.

On the inner surface of the hollow portion of the steel pipe pile 1 and the outer surface of the jointed steel pipe 2, in order to improve the adhesion of the mortar 3 and footing 4 to the concrete, a large number of protrusions 5 as a shear connector and other dowels are provided. It is projected or formed with a striped pattern.

The joint between the footing and the steel pipe pile is a place where the ability to absorb both the horizontal displacement of the ground and the horizontal displacement of the structure during an earthquake is required. This joint is made up of the rigidity of the pile 1 and the footing 4 as shown in FIG.
Compared with the rigidity of the steel pipe, only the connected steel pipe 2 has a small diameter, so the rigidity is small, and the steel pipe structure has concrete filled in the steel pipe, so the deformation performance is large and the external force due to a large earthquake, etc. Destruction precedes at the joint.

The vertical load acting on the footing is supported by the load directly transmitted to the steel pipe pile 1 and the load transmitted through the filling mortars 3.

In the embodiment shown in FIGS. 2 and 3, the upper part of the joint steel pipe 2 protruding from the head of the adjacent steel pipe pile 1 similar to the above-mentioned embodiment is connected by the connecting steel material 6. The horizontal load acting on the footing acts as a shearing force of the jointed steel pipe 2 and is transmitted to the steel pipe pile 1 via the filling mortars 3.

In this embodiment, the connecting steel member 6 is attached by welding the ends of two parallel thick steel plates to the side surface of the joint steel pipe 2 and welding. The combined steel pipe 2 and the connecting steel material 6 may be combined in advance and installed in the steel pipe pile 1 on site.

Shaped steel is used as the connecting steel material 6, and it is placed not only on the side surface of the joint steel pipe 2 but also on the top portion as shown in FIG. 4, and not only for welding but also for bolts and nuts as shown in FIG. It can also be joined to the joined steel pipe 2.

[0015]

As described above, according to the present invention having the above-mentioned constitution, the portion to be destroyed by the external force due to the large earthquake is specified, and how to strengthen the fracture boundary portion and design the building or the like. , It becomes possible to design by estimating how much the ability to withstand a large earthquake. In addition, since the construction process is simple and requires no effort, it is possible to provide a coupling method in which the construction period is shortened and the cost is accordingly reduced. Further, by using the bonded steel pipe of the present invention, it is possible to eliminate the embedding of footing in the pile head. Therefore, it is easy to arrange the bottom foot of the footing.

In the case of the conventional connection method of embedding the pile diameter in the footing of FIG. 7a, the bottom reinforcement of the footing cannot be arranged in the portion where the pile is present as shown in FIG. It is necessary and time consuming. In the case of the present invention, since the embedded jointed steel pipe is considerably smaller than the pile diameter, the portion where the footing lower end bar cannot be arranged is reduced, and the diagonal reinforcing bar is not necessarily required.

The joint between the footing and the steel pipe pile is a part that is required to have the ability to absorb the effects of both the horizontal displacement of the ground and the horizontal displacement of the structure during an earthquake. As shown in FIG. 1, the joint portion has only a joint steel pipe with a smaller diameter than the rigidity of the pile 1 and the rigidity of the footing 4, and the rigidity is small, and the steel pipe was filled with concrete. Since it has a steel pipe structure, it is characterized by high deformation performance. As a result, it is possible to design the failure to precede the external force due to a large earthquake at the joint boundary between the footing and the pile.

As shown in FIG. 6a, in the footing of the conventional structure, the shear strength of the concrete is weak with respect to the shear stress generated in the footing, so that the thickness thereof becomes large. On the other hand, in the present invention, the joint steel pipes are fixed in the footing concrete in the state of being connected by the connecting steel material having high rigidity, and the connecting steel material having high rigidity bears the shearing force acting on the footing as shown in FIG. 6b. Therefore, the footing can be made thinner.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is a vertical sectional view of another embodiment of the present invention.

3 is a cross-sectional view of FIG.

FIG. 4 is a vertical sectional view of a modified example of the present invention.

FIG. 5 is a cross-sectional view of a modified example of the present invention.

FIG. 6A is a conventional example, and b is an explanatory view of the operation of the present invention.

7A is a conventional example, and FIG. 7B is a bar arrangement diagram of a footing lower end streak of the present invention.

8A and 8B are vertical sectional views of a conventional example.

[Explanation of Codes] 1 ... Pile, 2 ... Combined steel pipe, 3 ... Mortars, 4 ... Footing, 5 ... Projection, 6 ... Connection steel material.

Claims (2)

(57) [Claims] 1. A steel pipe pile head is fixed by inserting a lower portion of a joint steel pipe having a diameter smaller than the pile diameter into the hollow portion, and filling mortar inside the joint steel pipe and in the gap between the joint steel pipe and the steel pipe pile. However, the joint steel pipe upper part protruding from the pile head is anchored in the footing concrete above the pile head, and the deformation performance of the joint between the pile head and footing is configured to be large. Joint structure. 2. The joint structure between a steel pipe pile and a footing according to claim 1, wherein a large number of projections serving as shear connectors are provided on the inner surface of the steel pipe pile and the outer surface of the joint steel pipe.