JPH0524703U - Connection structure of concrete filled steel tubular columns - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a joint structure that allows the compressive force to be transmitted substantially evenly inside the steel tube column even if the cast concrete in the steel tube column sinks and creates a cavity. To do. [Structure] A plurality of upper and lower diaphragms 2, 2 for joining a horizontal beam member 5 to a steel pipe column 20 filled with concrete
Are crossed and attached, and in the cross section of the diaphragms 2, 2, a filling hole 3 for opening the flow of the poured concrete is opened. Then, the plurality of diaphragms 2 and 2 arranged above and below are integrated with a plurality of reinforcing bars 7a that penetrate the diaphragms 2 and 2 and extend vertically in the steel pipe column 20. Even if the cavities 6a and 6b exist in the steel pipe column, the force that should be transmitted through the concrete if the cavities do not exist is reliably transmitted from the upper portion to the lower portion through the reinforcing bar material, and the concrete filling is performed. The compressive strength of the steel pipe column can be maintained at a desired value.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a joint structure of a concrete-filled steel pipe column, more specifically, a steel frame structure assembled by a concrete-filled steel pipe column for increasing the compressive force and a cross beam material connected to the steel pipe column. It relates to the joint structure of the concrete-filled steel tubular columns used for.

[0002]

[Prior Art]

 The steel frame structure mainly consists of steel pipe columns and cross beam members, and if necessary bracing materials are used. In the concrete-filled steel pipe column 1 shown in FIGS. 7 and 8, the upper steel pipe 1A, the middle steel pipe 1B, and the lower steel pipe 1C are connected at the portion where the steel pipe column is connected to the cross beam member. The upper diaphragm 2A is welded between the steel pipe 1A and the steel pipe 1B, and the lower diaphragm 2B is also welded between the steel pipe 1B and the steel pipe 1C. An upper flange 5a and a lower flange 5b of an H-shaped steel 5, which is a horizontal beam member, are welded and fixed to the upper diaphragm 2A and the lower diaphragm 2B of the steel pipe column 1 as described above. 5 are connected so as to extend to the left and right. On the other hand, since it is necessary to increase the compressive force of the steel pipe pillar 1, the concrete 8 is filled into the steel pipe pillar 1. In that case, a filling hole 3 penetrating through each diaphragm 2 inside the steel pipe column 1 is opened, and the concrete cast from the upper steel pipe 1A flows down to the middle steel pipe 1B and the lower steel pipe 1C. I am able to do it.

[0003]

[Problems to be solved by the device]

 By the way, the concrete 8 cast in the steel pipe column 1 has an unavoidable sinking phenomenon in the course of hardening. Therefore, it is inevitable that the cavities 6a and 6b are formed on the lower surface 2a side and the lower surface 2b side of the diaphragms 2A and 2B. That is, a cavity 6a is generated in the peripheral portion from the peripheral edge 3a of the filling hole 3 in the diaphragm 2A to the inner surface 1a of the middle steel pipe 1B, and also between the diaphragm 2B and the lower steel pipe 1C. When such cavities 6a and 6b are present, the compressive force transmitted from the steel pipe 1A located above to the steel pipe 1B located in the middle or the steel pipe 1B located in the middle to the steel pipe 1C located below. Of the compressive force, the compressive force transmitted to the concrete 8 in the steel pipes that are vertically aligned with each other is transmitted only through the opening area of the filling hole 3 which is smaller than the total cross-sectional area of the concrete 8. As a result, the compressive force transmission effect due to the concrete filling of the steel pipe column 1 is significantly reduced, and there is a problem that the yield strength of the steel pipe column 1 itself cannot be maintained high. When the above-mentioned cavities 6a and 6b are as small as 1 to 2 mm, they act as if the compressive force is transmitted through the total cross-sectional area of concrete in the steel pipe column 1, and the concrete-filled steel pipe column There is also research to ensure that the durability of No. 1 is secured to the extent that can be expected. On the other hand, the cavities 6a and 6b have been devised to be as small as possible. For example, a concrete mixing method that can improve the concrete pouring method and can suppress sedimentation is adopted. However, even with such efforts, there are always variations in construction. There is no current method to inspect for cavities from the outside, and as a result, extremely uncertain and unstable elements are involved, which results in compression of steel pipe columns even when filled with concrete. Improving yield strength is an undesired problem. The present invention has been made in view of the above-mentioned problems, and the purpose thereof is to form a cavity in the lower surface of the diaphragm after the concrete is placed in the steel pipe column, so that the steel pipe positioned above is transferred to the steel pipe positioned below. Even if the compressive force exerted cannot be transmitted through the entire cross section of the filled concrete, the yield strength of the steel tube column can be maintained without being affected by the quality of the concrete filling property, and therefore However, there is no need to inspect the filling property, and yet it is possible to use inexpensive ordinary cement and to provide a joint structure that can be an economical and reliable concrete-filled steel tubular column. ..

[0004]

Means for Solving the Problems The present invention is to install a plurality of upper and lower diaphragms for joining a horizontal beam member across a steel pipe to a steel pipe column filled with concrete, and the diaphragm has a substantially central portion in a transverse cross section. In addition, it is applied to a steel pipe joint structure in which a filling hole for allowing concrete to flow from an upper steel pipe to a lower steel pipe is opened. As shown in FIG. 1, the characteristic is that a plurality of diaphragms 2A, 2B arranged vertically are provided with a plurality of reinforcing bars 7a, 7a which penetrate the diaphragms 2A, 2B and extend vertically in the steel pipe column 20. Are integrated. Then, in the state where the concrete 8 is poured into the steel pipe column 20 to be filled and solidified, among the compressive forces acting on the steel pipe 20A located above the diaphragm 2A, the stress transmitted by the diaphragm 2A is the rebar material. Of the compressive force acting on the steel pipe 20B located above the diaphragm 2B so that it is transmitted to the steel pipe 20B located below via the steel bar 7a. That is, it is transmitted to the lower steel pipe 20C. As shown in FIG. 4, instead of the reinforcing bar 7a, the lower surface 2a of one of the diaphragms 2A, 2B arranged vertically extends downward in the steel pipe 30B located below the diaphragm 2A. A plurality of reinforcing bars 7c are integrated, and a plurality of reinforcing bars 7d extending downward in the steel pipe 30C located below the diaphragm 2B are integrated on the lower surface 2b of the diaphragm 2B. Then, in the state where the concrete 8 is poured into the steel pipe column 30 and is filled and solidified, the compressive force of the concrete 8 acting on the upper surfaces 2c and 2c of the diaphragms 2A and 2B is transmitted to the reinforcing bars 7c and 7d, The compressive force may be transmitted to the concrete 8 below by the adhesive force between the reinforcing bars 7c and 7d and the concrete 8.

[0005]

[Action]

 The upper diaphragm 2A is fixed by welding to the upper portion of the steel pipe 20B before the concrete 8 is cast, and the lower diaphragm 2B is fixed to the lower portion of the steel pipe column 20B by welding. In the center of the diaphragms 2A and 2B before being fixed, filling holes 3 and 3 for achieving the circulation of the concrete 8 are opened in advance, and the reinforcing bar 7a is penetrated to a position surrounding the filling holes 3 and 3. A plurality of insertion holes 9, 9 are provided. After a plurality of reinforcing bars 7a are penetrated through these insertion holes 9 so as to extend vertically in the steel pipe column 20, the reinforcing bars 7a are integrated with the diaphragms 2A and 2B by welding from the outside. The steel pipe 20B thus formed is placed on the steel pipe 20C located below, the reinforcing bar material 7a protruding downward is fitted into the steel pipe 20C, and the diaphragm 2B and the steel pipe column 20C are welded. Further, the steel pipe 20A is placed on the upper portion of the steel pipe column 20A, the reinforcing bar 7a protruding upward is fitted into the steel pipe 20A, and the diaphragm 2A and the steel pipe column 20A are welded to form one steel pipe column 20. In this way, when the steel pipe columns 20 are successively erected and the horizontal beam members are subsequently joined, the concrete 8 is poured into the steel pipe columns 20. During the hardening process, the particles settle down to form cavities of a certain size at the peripheral portions on the lower surface side of the diaphragms 2A and 2B. However, the plurality of reinforcing bars 7a, 7a provided at positions surrounding the filling holes 3, 3 extend vertically through the upper and lower cavities, respectively, and the concrete 8 filled in the steel pipe column 20 In the solidified state, part of the compressive force acting from above the diaphragms 2A, 2B is generated in the concrete 8 in the steel pipes 20B, 20C below through the reinforcing bars 7a, despite the presence of the cavities. It is transmitted, and the proof stress of the steel pipe column 20 is maintained at a desired size. In the configurations shown in FIGS. 4 and 5, when the diaphragms 2A and 2B are unitary, the reinforcing bar material 7c is fixed by welding. After that, the steel pipe column 30A is assembled in the same manner as described above. Then, the concrete 8 is placed in the same manner. Since the respective reinforcing bars 7c and 7d integrated with the lower surfaces 2a and 2b of the respective diaphragms 2A and 2B extend downward in the steel pipe column 30 through the respective cavities generated when the concrete is hardened. , The compressive force acting on each diaphragm upper surface 2c, 2d is transmitted to the reinforcing bars 7c and 7d, and the adhesive force between the reinforcing bars 7c, 7d and the concrete 8 transmits the compressive force to the concrete 8 below. The proof stress of the steel pipe column 30 is secured at a desired value.

[0006]

EFFECTS OF THE INVENTION According to the present invention, since the plurality of diaphragms arranged above and below are integrated with the plurality of reinforcing bars extending vertically in the steel pipe column through the diaphragms, the steel pipe above the diaphragm is integrated. The compressive force acting on is transmitted to the lower steel pipe through the reinforcing bar material. At that time, even if the cross section of the filled concrete is partially reduced due to the presence of cavities, the reinforcing steel member takes charge of transmitting the compressive force, and the proof stress as the steel pipe column is exerted as desired. It is no longer necessary to check the existence and size of cavities that occur after concrete is poured into steel pipe columns, and the same effect as in the ideal case in which the compressive force can be transmitted by the entire cross section of internal concrete is obtained. Therefore, it is not necessary to devise a method to minimize the generation of voids, to improve the concrete pouring method, or to adopt a special mixing method for concrete that suppresses sedimentation. Moreover, it enables the use of ordinary cement and realizes an inexpensive and reliable concrete-filled steel tubular column. Even when a plurality of reinforcing bars extending downward in the steel pipe column are integrated for each lower surface of each diaphragm, the same effect as described above is exhibited. In this case, the amount of the reinforcing steel used can be reduced as compared with the above.

[0007]

【Example】

 Hereinafter, the joint structure of the concrete-filled steel tubular column of the present invention will be described in detail with reference to the drawings. FIG. 1 is a vertical sectional view of a joint portion of a steel pipe column 20, and FIG. 2 is a sectional view taken along the line AA of FIG. The concrete-filled steel pipe column 20 is composed of a steel pipe 20A located above, a steel pipe 20B located in the middle, and a steel pipe 20C located below. Then, the upper and lower diaphragms 2A and 2B for joining the H-shaped steel as the horizontal beam member 5 indicated by the two-dot chain line are attached, and after these diaphragms 2 are integrated with the plurality of reinforcing bar members 7 and 7. The structure is filled with concrete 8. In this example, square steel pipes having a rectangular cross section are adopted as the steel pipes 20A to 20C, the upper steel pipe 20A and the lower steel pipe 20C have a length substantially equal to the height of each floor in the steel structure, and the middle steel pipe 20B has a cross beam material. The length is approximately equal to the height of 5. The diaphragm 2 is made of a thick steel plate cut into a rectangle slightly larger than the steel pipe column 20, and a filling hole 3 for distributing the concrete 8 that is cast from above is provided at a substantially central portion of each of the diaphragms 2A and 2B. Is opened. Further, at a position surrounding the filling hole 3, there is provided an insertion hole 9 for passing twelve reinforcing bars 7a, 7a out of a total of eighteen reinforcing bars 7. The reinforcing bar material 7 is a deformed reinforcing bar material having ribs and nodes formed on the surface thereof. When the reinforcing bar material 7 is vertically passed through the through holes 9 and 9 described above, the upper surfaces of the diaphragms 2A and 2B are, as will be described later. Alternatively, it is fixed by welding from the lower surface. In this example, six rebar members 7b, 7b, which are in contact with the peripheral edge 3a of the filling holes 3, 3 and are arranged at equal intervals and extend vertically, are also fixed by welding. In this way, the reinforcing bars 7 and 7 integrated with the diaphragms 2A and 2B maintain the vertical posture, and the steel pipe pillars 20 extend from the upper steel pipe 20A through the middle steel pipe 20B to the lower steel pipe 20C. Placed inside. Therefore, if there are many floors, there are as many joints with such a structure. The horizontal beam member 5 is fixed to the steel pipe column 20 by welding the horizontally extending upper flange 5a and lower flange 5b to the end faces of the diaphragms 2A and 2B protruding from the steel pipe column 20.

Further, the reinforcing bar material 7 and the diaphragms 2A and 2B are integrated with each other during the procedure of assembling the steel pipe column 20 as shown in FIG. First, as shown in FIG. 3A, the middle steel pipe 20B, the upper diaphragm 2A provided with the filling hole 3 and the insertion holes 9, 9 and the lower diaphragm 2B having the same shape as the diaphragm 2A are arranged. Be prepared. As shown in FIG. 3 (B), the diaphragms 2A and 2B are fixed to the middle steel pipe 20B by welding so that the corresponding filling holes 3 and 3 and the insertion holes 9 and 9 are aligned vertically. It First, twelve reinforcing bars 7a are passed through the insertion holes 9 and fixed by the upper surface of the diaphragm 2A and the lower surface of the diaphragm 2B. If necessary, the six rebar members 7b are also brought into contact with and welded to the peripheral edges 3a of the upper and lower filling holes 3,3. Next, as shown in FIG. 3 (C), the steel pipe 20C is arranged below the middle steel pipe 20B in which the diaphragms 2A and 2B and the reinforcing steel 7 are integrated, and the downward projecting portion of the reinforcing steel 7 is the steel pipe 20C. It is housed inside. Similarly, the steel pipe 20A is arranged in the upper part, and the upward projecting portion of the reinforcing bar 7 is housed in the steel pipe 20A to be in a stacked state. Finally, as shown in FIG. 3 (D), the upper steel pipe 20A is fixed to the diaphragm 2A by welding, and the lower steel pipe 20C is welded to the diaphragm 2B. Then, as shown in FIG. 1, the H-shaped steel 5 as a cross beam member is integrated with the diaphragms 2A and 2B by welding or the like. By such a procedure, a number of steel pipe columns 20, 20 and a large number of cross beam members 5 are combined to construct a steel frame structure. Concrete kneaded is poured from above the steel pipe 20A, and the concrete 8 is sequentially filled into the steel pipes 20B and 20C at the lower position while flowing down the filling hole 3. During the hardening process, the concrete 8 sinks, and spaces are created at the peripheral portions of the diaphragms 2A, 2B on the lower surfaces 2a, 2b side. That is, a cavity 6a is formed at a peripheral portion extending from the peripheral edge 3a of the filling hole 3 of the diaphragm 2A to the inner surface 20a of the steel pipe 20B, and a cavity 6b is formed at a peripheral portion extending from the peripheral edge 3a of the filling hole 3 of the diaphragm 2B to the inner surface 20b of the steel pipe 20C. Occurs.

In the concrete-filled steel pipe columns 20 in the steel frame structure thus constructed, the load from each member acts downward as a compressive force, and the steel pipes 20 A, 20 B, 20 C and the concrete 8 are sequentially applied. Transmitted. In such a state, the concrete 8 is constricted by the cavities 6a and 6b at each position where the filling hole 3 is located, and the cross-sectional area of the concrete 8 at which the compression force is transmitted becomes small. Since there is a limit to the compressive force that the concrete 8 can transmit per unit area, the compressive force that the concrete 8 can support is extremely small compared to the case where the cavities 6a and 6b are not provided. However, even if the compressive force sharing ratio of the concrete 8 is lowered in this way, the twelve reinforcing bars 7a, 7a vertically passing through the cavities 6a, 6b and the peripheral edge 3a of the filling holes 3, 3 are passed. The rebar members 7b, 7b of the book complement the transmission of the compressive force by taking over. That is, of the compressive force transmitted from the upper steel pipe 20A to the middle steel pipe 20B and the like, the stress component acting on the plate surfaces of the diaphragms 2A and 2B excluding the filling hole 3 is transmitted by the reinforcing bar material 7. Therefore, the compressive force in the steel pipe column 20 is shared by the steel pipe, the concrete, and the reinforcing bar material, while the steel pipe column 20 as a whole exhibits a desired yield strength, and a large stress variation in the transverse section of the steel pipe column 20 or a local stress is locally generated. It also prevents the occurrence of low load bearing parts.

In a reinforced concrete column or the like, a concrete portion has a high proof stress against a compressive force, but in order to complement a weak point against a bending load, a reinforced concrete material having high toughness is used. However, in the present invention, the rebar material is made to bear a compressive force in a portion where continuity of concrete is difficult to be obtained, which is different from the conventional use as a reinforcing rebar material. Be understood. Of course, the reinforcing bar 7 also functions to counter the bending force received from the cross beam 5, etc., but the bending resistance as a column was originally provided in the steel pipes 20A, 20B, 20C, and the bending of the reinforcing bar 7 You don't have to expect resistance. The length of the reinforcing bar 7 exposed from the concrete 8 in the cavities 6a and 6b is several mm to ten and several mm, and the reinforcing bar 7 does not buckle due to the compressive load. As described above, the concrete-filled steel tubular column 20 has a large proof stress even if the cavities 6a and 6b are present, that is, even if the proof stress of the steel tubular column is good or bad in the filling property of the concrete, and the compressive force is almost the same. Uniform transmission is achieved. As a result, it is not necessary to take measures to make the cavities as small as possible, and it is not necessary to improve the concrete casting method or adopt a special mixing method for concrete that suppresses sedimentation. Moreover, the work of inspecting the filling property of concrete is omitted, and in addition, the use of inexpensive ordinary cement can significantly reduce the construction cost.

FIG. 4 is an example of the joint structure of concrete-filled steel tubular columns having different configurations. The construction of the concrete-filled steel pipe column 30 and the joining state with the H-section steel 5 are the same as those in the above-mentioned example. In this example, a plurality of reinforcing bar members 7 extending downward in the steel pipe column 30 are welded to the lower surfaces 2a and 2b of the diaphragms 2A and 2B arranged one above the other at the time of (A) in FIG. To be done. The reinforcing bar material 7c attached to the diaphragm 2A is located inside the middle steel pipe 30B, while the reinforcing bar material 7d of the diaphragm 2B is located inside the lower steel pipe 30C. By the way, the reinforcing bars 7c and 7d are extended downward and are selected long enough to obtain a large adhesion with the concrete 8. In the illustrated example, the upper end of the reinforcing bar 7 is not projected on the upper surfaces of the diaphragms 2A and 2B, but it may be projected as shown by a broken line if necessary. In addition, in FIG. 5, only the reinforcing bars 7c and 7d are provided, and the reinforcing bars 7e are not welded to the peripheral edge 3a of the filling hole 3 as shown in FIG. May be added. In the case of this example, paying attention to one rebar material 7, since it does not vertically pass through the upper and lower two diaphragms 2A and 2B, at the time of the operation of FIG. No alignment is required and assembly accuracy is not as demanding as in the previous example. Further, since the transmission of the compressive force is based on the idea that the force acting on the upper surfaces 2c and 2d of the diaphragms 2A and 2B is added to the reinforcing bar material 7, the reinforcing bar material 7 itself may be shorter than in the case of FIG. Saves money. Even in such a configuration example, as in the case of FIG. 1, the compressive force acting on the steel pipe column 30 is a force that the steel pipe, the concrete, and the reinforcing steel bar respectively contribute, and the desired yield strength of the steel pipe column 30 is secured. It It should be noted that although the examples shown in the drawings are square steel pipes, it goes without saying that the same applies to steel pipe columns composed of round steel pipes.

Here, a calculation example for selecting the diameter of the reinforcing bar material applied to the concrete-filled steel tubular column will be described with reference to FIG. As a cross-sectional dimension, it is assumed that a diaphragm 2 having a filling hole 3 with a diameter d = 200 mm is adopted in a square steel tube 40 having a vertical width L = 500 mm, a horizontal width W = 500 mm, and a wall thickness t = 22 mm. Filled concrete cross-sectional area A in the steel pipe column 40_CIs A_C= (50-2.2)²= 2284.8 cm²  Cross-sectional area A of filling hole 3_JIs A_J= Π × 10²= 314.2 cm²  Cross-sectional area A of cavities 6a and 6b_hIs A_h= A_C-A_J= 1970.6 cm²Becomes If there is no cavities 6a and 6b according to the above and concrete 8 is present, the compressive force Pt transmitted at that portion is the allowable yield strength of concrete 8 of 70 Kg / cm.²Then, Pt = A_h× 70 = 137,942 Kg On the other hand, the allowable yield strength of the reinforcing bar material 7 is 2000 Kg / cm.², N is the number of used pieces, and each cross-sectional area is A_tcm²Then, n × A_tX2000 = From Pt, n x A_t= 68.97 cm²Becomes Therefore, in the case of the reinforcing bar material 7 having a diameter Dt = 29 mm, n = 10.45, which is at least 11. Assuming that they are evenly arranged around the steel pipe, it will be understood that the 12 shown in the figure may be adopted. However, with this number of steel bars, the surroundings of the placed concrete will not be impaired. The above calculation example is described as an example corresponding to FIG. 5, but the same applies to the case of FIG. In each case, there is only a difference in that the length of the reinforcing bar material 7 is selected in consideration of the adhesive force with concrete.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the structure of a concrete-filled steel pipe column joint in the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

3 (A) to (D) are explanatory views of an assembly procedure of a steel pipe column.

FIG. 4 is a vertical cross-sectional view of a joint portion structure of a steel pipe column in another example.

5 is a sectional view taken along the line BB of FIG.

FIG. 6 is an explanatory diagram for determining the number of reinforcing bars used in a steel pipe column and the cross-sectional diameter thereof.

FIG. 7 is a vertical cross-sectional view showing the structure of a conventional concrete-filled steel pipe column joint portion.

8 is a cross-sectional view taken along the line CC of FIG.

[Explanation of symbols]

2, 2A, 2B ... diaphragm, 2a, 2b ... lower surface, 2
c, 2d ... Diaphragm upper surface, 3 ... Filling hole, 5 ... Cross beam material (H-shaped steel), 7, 7a, 7c, 7d ... Reinforcing bar material, 8 ... Concrete, 20, 30 ... Steel tube column, 20A, 30A ... Above Steel pipes located (upper steel pipes), 20B, 20C ... Steel pipes located in the middle (intermediate steel pipes), 30B, 30C ... Steel pipes located below (lower steel pipes).

Claims (2)

[Scope of utility model registration request] 1. A plurality of upper and lower diaphragms for joining a horizontal beam member are attached across a steel pipe to a steel pipe column filled with concrete, and a steel pipe located above the steel pipe is placed at a substantially central portion of the cross section of the diaphragm. In a steel pipe joint structure in which a filling hole that facilitates the circulation of concrete to the steel pipe located below is opened, a plurality of diaphragms arranged above and below extend through the diaphragms vertically in the steel pipe column. In the state where the steel rebar material of is integrated and the concrete is filled and solidified in the steel pipe column, of the compressive force acting on the steel pipe located above the diaphragm, the stress transmitted by the diaphragm is A joint structure of a concrete-filled steel pipe column characterized by being transmitted to a steel pipe located below through a reinforcing steel material. 2. A plurality of upper and lower diaphragms for joining a horizontal beam member are attached across a steel pipe to a steel pipe column filled with concrete, and a steel pipe located above the steel pipe is placed at a substantially central portion of the cross section of the diaphragm. In a steel pipe joint structure in which a filling hole for allowing concrete to flow into a steel pipe located below is opened, the lower surface of each of the diaphragms arranged above and below extends downward in the steel pipe located below the diaphragm. In the state where a plurality of reinforcing bars are integrated and the steel pipe column is filled with concrete and solidified, the compressive force of concrete acting on the upper surface of the diaphragm is transmitted to the reinforcing bars, and the reinforcing bars and concrete The above-mentioned compressive force is transmitted to the concrete below by the adhesive force. Part structure.