JPH07107301B2 - End reinforced structure of reinforced concrete coated steel tubular columns - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a structure for reinforcing an end portion of a reinforced concrete-coated steel pipe column.

(Prior Art) In a reinforced concrete-coated steel pipe column, a steel pipe (a) having a rectangular or circular cross section is coated with reinforced concrete (b), and the steel pipe is laterally bundled with reinforced concrete to maintain the integrity of both.
It is designed to prevent buckling and resist external forces.
(See FIG. 9) In the figure, (c) is a main bar and (d) is a stirrup. FIG. 10 shows a frame structure using the reinforced concrete-coated steel tubular column (A), where (B) is a beam and (C) is a slab.

(Problems to be solved by the invention) In a column to which axial pressure acts, a large compressive force acts on the column end along with a bending moment, whereby concrete at the column end is destroyed, and the steel pipe end buckles, It is easy to cause a decrease in yield strength.

Therefore, higher strength concrete is required, and it is necessary to use steel frame having a small width-thickness ratio (thickness).

The present invention has been proposed in view of the above problems of the prior art, the purpose of the purpose, compared to the conventional reinforced concrete-coated steel pipe column, concrete destruction of the column end,
The purpose of the present invention is to provide a reinforced concrete-coated steel pipe column end reinforcing structure in which buckling of the steel pipe hardly occurs and the structural performance is improved.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an end portion reinforcing structure of a reinforced concrete-coated steel tubular column according to the present invention has an axial direction by a bending moment applied to the reinforced concrete-coated steel tubular column end portion outer periphery. It is configured by stacking a plurality of steps of outer steel pipes having a small width in which no directional force is generated so as to be stacked and wound in the height direction of the column.

(Operation) Since the present invention is configured as described above, the inner steel pipe column tries to expand outward due to the compressive force acting on the end of the reinforced concrete-coated steel pipe column together with the bending moment, so that the steel pipe outer periphery The coated reinforced concrete part of is subjected to lateral force.

The reaction force of the lateral force is generated by a plurality of narrow-width steel pipes wound on the outside of the concrete portion, and thus the reinforced concrete portion is tightened from the inside and outside.

At this time, if the width of the steel pipe wound on the outside is large, an axial force also occurs in the outside steel pipe when a bending moment acts, and the force for restraining the coated reinforced concrete is weakened, but this According to the invention, since the width of the outer steel pipe is small and the axial deformation of the outer steel pipe itself does not occur, a sufficient restraining force is applied to the coated reinforced concrete to increase the compressive strength of the concrete.

(Examples) The present invention will be described below with reference to illustrated examples.

(1) is an inner steel tubular column in a reinforced concrete-coated steel tubular column (A), the outer periphery of which is coated with reinforced concrete (2). In the figure, (3) is the main bar, (4) is the stirrup, (5)
Is a stud bolt. The stud bolt (5) is attached only to the hinge zone at the end of the column.

An outer steel pipe (6) having a small width, in which an axial force is not generated by a bending moment acting on the column, is provided at the column head and column base of the reinforced concrete-coated steel pipe column (A),
The pillars are wound and overlapped in the height direction. (See FIGS. 1 and 2) Note that FIG. 2 shows a frame structure using the reinforced concrete-coated steel tubular column (A), where (B) is a beam and (C) is a slab.

The above-mentioned embodiment shows a case where the present invention is applied to a reinforced concrete-coated steel tubular column (A) having a rectangular cross section, while FIG. 3 shows a case where the present invention is applied to a reinforced concrete coated steel tubular column (A) having a circular cross section. In the figure, the same parts as those in the above embodiment are designated by the same reference numerals.

Since the illustrated embodiment is configured as described above, the inner steel pipe column (1) is moved to the x direction in FIG. 4 by the axial compression force acting on the end of the column (A) together with the bending moment.
As shown in Fig. 4, the compressive force causes axial contraction and lateral extension, resulting in an attempt to expand outward, whereby the outer peripheral reinforced concrete (2) receives a lateral force as indicated by y. Further, no axial force acts on the outer steel pipe (6), the reaction force z of the lateral force is generated by the outer steel pipe (6), and the reinforced concrete (2) part is divided into the inner steel pipe column (1) and the outer steel pipe (6). The reinforced concrete part (2) receives a lateral restraining force and its strength rises, causing the concrete at the end of the column to break and buckling of the steel pipe, compared to conventional reinforced concrete-coated steel pipe columns. Is less likely to occur.

FIG. 5 is a bending moment distribution diagram and a skewness distribution diagram of the reinforced concrete-coated steel tubular column constructed as described above.

At this time, if the width of the outer steel pipe (6) is large, as shown in FIG. 6, when the bending moment M acts, the outer steel pipe (6) contracts in the direction of arrow u, and the outer steel pipe (6) also An axial force is generated and the restraining force on the reinforced concrete (2) is weakened, but the outer steel pipe (6) having a sufficiently small width
As shown in FIG. 7, when it is used, the axial deformation of itself does not occur, so that the reinforced concrete (2) can be sufficiently used.
Can act as a binding force against.

FIG. 8 shows the case where the outer steel pipe (6) and the column surface are on the same plane. Due to the design, the outer steel pipe (6) has a bending moment and an axial force.
Will be wound on the outside of the design cross-section to prevent it from working.

Therefore, in order to make the outer steel pipe (6) the same as the column surface, the column portion where the outer steel pipe (6) is not wound is to be expanded in diameter. At this time, it is necessary to pay attention so that the axial pressure does not act directly on the outer steel pipe (6), and the deformation amount may be either above or below the outer steel pipe (6) or between the steel pipes (6). Accordingly, the interval t is provided.

(Effects of the Invention) According to the present invention, as described above, a plurality of stages of outer steel pipes having a sufficiently small width that no axial force is applied by a bending moment applied to the column is provided on the outer periphery of the end of the reinforced concrete-coated steel pipe column. By stacking and winding in the height direction, the inner steel pipe column expands to the outside by the axial compressive force, and the inner steel pipe column and the outer steel pipe restrain the coated reinforced concrete to increase the strength. As a result, as compared with the conventional reinforced concrete-coated steel tubular column, concrete destruction at the column end portion and buckling of the steel tubular column are less likely to occur, and the structural performance is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional plan view showing an embodiment of a reinforced concrete-coated steel pipe column having an end reinforcing structure according to the present invention.
FIG. 2 is a front view showing a frame structure using the steel pipe column, FIG. 3 is a cross-sectional plan view showing another embodiment of the present invention, and FIG. 4 is a function of the present invention. Explanatory drawing, FIG. 5 is a bending moment distribution diagram and a skewness distribution diagram of the steel pipe column, FIGS. 6 and 7 are action explanatory diagrams of the outer steel pipe, and FIG. 8 is a longitudinal section showing another embodiment of the present invention. FIG. 9 is a cross-sectional plan view of a conventional reinforced concrete-coated steel pipe column, and FIG. 9 is a cross-sectional view taken along the line XX of FIG.
FIG. 10 is a front view of a frame using the steel pipe column. (A) ... Reinforced concrete-coated steel tube column, (1) ... Inner steel tube column, (2) ... Reinforced concrete, (6) ... Outer steel tube.

Claims (1)

[Claims] 1. A plurality of steps of outer steel pipes having a small width in which an axial force is not generated due to a bending moment applied to the column is wound around the outer periphery of the end of the reinforced concrete-coated steel pipe column so as to be stacked in the height direction of the column. A reinforced concrete-coated steel tube column end reinforcement structure characterized by being worn.