JPH0515853B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an unbonded filled steel pipe structure used for columns, piles, etc.

[Prior art] A filled steel pipe concrete structure is known as this type of structure, but the conventional filled steel pipe concrete structure is simply a vertically erected steel pipe that also serves as a formwork, and the inside is filled with concrete. The steel pipe and concrete are in a bonded state and mechanically behave as one.

[Problems to be solved by the invention] However, in the conventional method, when compressive force in the axial direction is applied, the steel pipe and concrete are distorted as one, and if the steel pipe is significantly distorted, the steel pipe may exceed the Mises yield condition. , local buckling may occur.

Therefore, even though there is plenty of margin for circumferential stress and the confining effect of the steel pipe (the effect of tightening the concrete that is about to expand due to the circumferential stress of the steel pipe) can be expected to sufficiently increase the yield strength of concrete, the increase in The steel pipe almost reaches yield due to the axial stress, and the confining effect cannot be fully exerted, resulting in a column or pile with a larger cross-sectional area than necessary.

An object of the present invention is to provide an unbonded filled steel pipe structure that can make full use of the confining effect of steel pipes, significantly improve compressive strength, and have a smaller cross-sectional area than conventional ones.

[Means for Solving the Problems] The structure of the present invention, in which a structural filler is filled inside a steel pipe, divides the steel pipe into two in the axial direction, and connects the inner circumference of the steel pipe between the ends of the two halves. A cylindrical or polygonal cylindrical deformation absorbing member having an inner circumferential surface substantially flush with the surface and absorbing axial deformation occurring in the steel pipe is interposed, and this deformation absorbing member has high strength and high rigidity. A structure in which fibers with The structure is characterized in that an unbonding layer is provided on the interface between the structural filler and the steel pipe to prevent adhesion between the steel pipe and the structural filler.

In this case, examples of fibers having high strength and high rigidity include aramid fibers, glass fiber fibers, carbon fibers, and the like.

[Function] In the unbonded filled steel pipe structure having the above configuration, when an axial compressive force is applied, the steel pipe can freely deform in the axial direction, and the deformation is absorbed by the deformation absorbing member.

Particularly in this case, the steel pipe and the structural filler filled inside are in an unbonded state, so the axial compressive force acts only on the structural filler inside the steel pipe and hardly acts on the steel pipe. . That is, the axial stress acting on the steel pipe becomes close to zero. Therefore, only the ring tension acting as a reaction that gives a confine effect acts on the steel pipe.

Here, the ring tension also acts on the deformation absorbing member, but since the deformation absorbing member is made by winding high strength and high rigidity fibers into a cylindrical shape and binding them with a solidifying material, the ring tension acts on the deformation absorbing member. The strength is approximately the same as that of a steel pipe, and a sufficient confining effect can be exerted even in the deformation absorbing member portion.

Therefore, by applying the Mises yield condition, the confining effect of the steel pipe due to the circumferential stress can be fully exhibited, and as a result, the strength against compressive loads can be significantly improved, and the cross-sectional area can be reduced.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

1 to 3 show an embodiment in which the present invention is applied to a column H, in which 1 is a steel pipe with a circular cross section. The steel pipe 1 is axially divided into two at a predetermined point in the axial direction, and between the ends of the divided steel pipe 1, the inner diameter of the steel pipe 1 is approximately the same as the inner diameter of the steel pipe 1.
A cylindrical deformation absorbing member 2 is interposed to absorb deformation in the axial direction that occurs.

As shown in FIG. 2, the deformation absorbing member 2 is made by tightly winding fibers 3 having high strength and high rigidity into a cylindrical shape, and combining them with a solidifying material 4 having at least lower strength and lower rigidity than the steel pipe 1; For example, it is made of rubber, vinyl chloride, or PEEK resin, etc., and is integrally bound and molded to prevent it from unraveling. Therefore, although it deforms in the axial direction, it deforms in the circumferential direction.
It hardly deforms in the radial direction and has high strength and rigidity.

The deformation absorbing member 2 is connected to the steel pipe 1 by cutting out the upper and lower outer circumferential surfaces of the deformation absorbing member 2 in a stepped manner, and by cutting out the inner circumferential surface of the end of the steel pipe 1 in a stepped manner. This is achieved by mutually inserting each end of the steel pipe 1 and the deformation absorbing member 2 into the notch. In this case, the thickness and length of the deformation absorbing member 2 should be set in accordance with the strength of the steel pipe 1 and the magnitude of deformation occurring in the steel pipe 1.

Further, on the inner surface of the steel pipe 1 configured as described above, a separation material (unbond treatment layer) is provided to prevent adhesion between the steel pipe 1 and the filling material filled inside the steel pipe 1.
5 is applied in advance, and then concrete 6 is cast and filled inside the steel pipe 1. in this case,
As the separation material 5, paraffin, asphalt,
An unbonding layer is formed by applying oil, grease, vaseline, etc. to the inner surface of the steel pipe 1.

The pillar H of the unbonded filled steel pipe structure constructed in this manner is erected as a frame structure, as shown in FIG. In this case, in the column H, the deformation absorbing member 2 is provided at the intermediate portion between each floor, which is the recursion point of the bending moment, and is designed to absorb deformation occurring in the steel pipe 1 for each floor.
In addition, 7 is the joint part of the beam of each floor.

In such a filled steel pipe structure, compressive force in the axial direction acts on the concrete 6 inside the steel pipe 1,
When the concrete 6 is compressed and exceeds a predetermined strength, the concrete 6 undergoes axial strain and sudden transverse strain in the radial direction.

However, the axial strain that occurs in the steel pipe 1 is absorbed by the deformation absorbing member 2, and no axial stress is transmitted between the upper and lower parts of the deformation absorbing member 2, and almost no axial stress is generated in the steel pipe 1. In particular, in this case, the steel pipe 1 is in an unbonded state with the filling concrete 6, and the steel pipe 1 is not restrained by the concrete 6 in the axial direction at all. Therefore, although axial strain occurs in the concrete 6, no axial strain occurs in the steel pipe 1. Therefore, by applying the Mises yield condition, the confinement effect of the steel pipe 1 due to circumferential stress can be fully exhibited,
As a result, the strength against compressive loads can be improved and the cross-sectional area can be reduced.

In the above embodiment, the steel pipe 1 is filled with concrete, but it may be filled with mortar, other hydraulic materials, soil, sand, metal powder, glass powder, plastic, viscosity, etc. Structural fillers with high compressive strength may be substituted. Furthermore, it is optional to increase the strength of the concrete by inserting reinforcing bars into the concrete or arranging prestressed steel.

Further, in the above embodiment, the cross section is circular, but the present invention can of course be applied to the case where the cross section is octagonal as shown in FIG. 4, or other polygonal shapes. 11 in Figure 4 is a polygonal steel pipe, 1
6 is concrete.

[Effects of the Invention] According to the present invention, the axial deformation occurring in the steel pipe is
Almost no axial stress is applied to the steel pipe because the deformation is absorbed by the deformation absorbing member made of high-strength, high-rigidity fibers wound into a cylindrical shape. Therefore, by applying the Mises yield condition, the effect of confining the steel pipe due to the circumferential stress can be fully exhibited.
As a result, the strength against compressive loads can be significantly improved and the cross-sectional area can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a half sectional view of the main part of an embodiment of the present invention, Fig. 2 is a perspective view showing the structure of the core of the deformation absorbing member, Fig. 3 is an overall sectional view of the embodiment, and Fig. 4. FIG. 2 is a cross-sectional view of another embodiment of the present invention. 1, 11... steel pipe, 2... deformation absorbing member, 3...
...Fiber with high strength and high rigidity, 4...Solidifying material, 5
... Separation material (unbond treatment layer), 6, 16 ...
concrete.

Claims (1)

[Claims] 1 In a structure in which the inside of a steel pipe is filled with a structural filler, the steel pipe is divided into two in the axial direction, and the ends of the two halves have an inner circumferential surface that is substantially flush with the inner circumferential surface of the steel pipe. In addition, a cylindrical or polygonal cylindrical deformation absorbing member is interposed to absorb the axial deformation that occurs in the steel pipe. The steel pipe is wound into a shape and integrally bound and formed with a solidifying material having at least lower strength and stiffness than the steel pipe, and the interface between the steel pipe and the structural filler filled in the steel pipe is An unbonded filled steel pipe structure characterized by being provided with an unbonded treatment layer for eliminating adhesion between the steel pipe and structural filler.