JP4785167B2 - Reinforcement structure of column base in steel pipe structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for reinforcing a column base in a steel pipe structure using a steel pipe itself or a concrete-filled steel pipe as a steel column.
[0002]
[Prior art]
Attention has recently been paid to technical problems such as anchor bolts that fix steel column bases to foundation concrete being broken by repeated loading of tension and compression during earthquakes, which can cause buildings to collapse. . In order to eliminate such damage, countermeasures such as increasing the number of anchor bolts have been taken. In this countermeasure, however, the increased anchor bolts will cause the bar arrangement in the foundation concrete to be included. There is a technical difficulty that the work becomes complicated and not only the workability is hindered but also the cost is increased. In addition, since the installation of anchor bolts requires very high installation accuracy, the construction required a high technical level and a large work load.
[0003]
Therefore, as a reinforcement technology for the column base of the steel pipe structure, in addition to anchor bolts that fix the base plate integrally provided at the lower end of the steel pipe column to the foundation concrete, reinforcing bars are inserted and installed inside the lower part of the steel pipe column. Further, a technical means for reinforcing the column base portion using the fixing force is disclosed (Japanese Patent Laid-Open No. 2000-297480). According to this conventional technology, the inner space of the steel pipe is used to install the internal anchors made of reinforcing bars, etc., so that a large number of anchors are not concentrated only on the periphery of the base plate, and tightening is possible. Since the installation positions are distributed between the anchor bolts and the internal anchors, the workability related to the installation is improved, and the degree of hindering the reinforcement work of the foundation concrete portion is greatly reduced. However, since the internal anchor simply inserts the reinforcing bar inside the lower part of the steel pipe column, a large fixing action cannot be expected, and it is necessary to increase the installation length in the steel pipe, which is at least 20 times the diameter of the reinforcing bar. It was necessary to take about twice.
[0004]
[Problems to be solved by the invention]
The present invention was invented in view of the conventional technical situation as described above, and reinforces the column base portion of the steel pipe structure by installing the internal anchor made of a reinforcing bar or the like by utilizing the internal space of the steel pipe column. Therefore, it is an object to improve the reinforcing action so that it can be realized more effectively and rationally.
[0005]
[Means for Solving the Problems]
In the present invention, in order to solve the above-mentioned problem, attention is paid to the fracture mode of the anchor material. The fracture forms of anchor materials can be roughly divided into the following three forms. In other words, failure mode in which anchor material is weak and anchor material is pulled out and destroyed, failure mode in which anchor force is strong with foundation concrete and anchor material breaks and breaks, anchor material is strong and foundation concrete is fixed It can be roughly classified into a fracture mode in which a cone is broken from a conical surface of approximately 45 degrees with the member as the top. The present invention pays attention to the fact that the last cone breaking mode is effective for strengthening the fixing force in this case, and the reinforcing action of the internal anchor inserted and installed in the lower inner side of the steel pipe column is more effective. It is configured so that it can be realized reasonably. That is, in the present invention, in the column base portion of the steel pipe structure in which the base plate integrally provided by welding or the like at the lower end portion of the steel pipe column is tightened and fixed using the anchor bolt fixed to the basic concrete, the steel plate column is attached to the base plate. A central opening is formed with the inner flange protruding inward, and an inner anchor is inserted into the lower inner side of the steel pipe column through the central opening, and in the vicinity of the upper end of the inner anchor. While installing the fixing member, the cone breaking surface composed of a truncated cone-shaped conical surface whose upper part is cut by the fixing member, the cone angle between the fixing member and the internal anchor is approximately 45 degrees . as according to the inner brim portion of at least the base plate, i.e. the so intersect at least the inner flange portion and the cone fracture surface formed from the conical surface, their fixing member and the base The state of holding the positional relationship between the inner brim portion of the rate, adopts the technical means of placing the inner anchor. As a result, the inner anchor has its cone breaking surface disposed at least in a positional relationship with respect to the inner flange portion of the base plate, so that the fixing force based on the fixing member provided on the inner anchor protrudes inward of the steel pipe. Rutotomoni can be effectively transmitted to the steel pipe side via the inner flange portion, the insertion amount projecting into the steel tube of the internal anchor that is longer than necessary is suppressed more the columnar leg portion of the steel pipe structure Effective and reasonable reinforcement is possible.
[0006]
According to a second aspect of the present invention, a conical surface having the center of the fixing member as a vertex and a conical angle with the inner anchor of approximately 45 degrees is a joint portion between the inner flange portion and the steel pipe column. In other words, the inner anchor is installed so that the positional relationship between the fixing member and the inner flange of the base plate is maintained so as not to exceed the inner edge of the joint between the base plate and the steel pipe column. Thus, the length of the inner anchor can be reduced more easily and accurately . This is because the fixing action by the fixing member is set so as to be supported by the inner flange, assuming cone breakage occurring at least from any part between the center of the fixing member and the outer periphery of the fixing member. It is sufficient if the inner anchor is longer than that, so that the conical surface as a boundary surface of the cone fracture generated from the center of the fixing member exceeds the joint between the inner flange and the steel pipe column. This is because the fixing force of the internal anchor cannot be effectively increased only by the increase due to the adhesive force even if it is set. That is, as described above, the conical surface with the center of the fixing member as the apex and the conical angle with the internal anchor being approximately 45 degrees does not exceed the joint between the inner flange and the steel pipe column. If set in this way, the length of the inner anchor can be reduced more reasonably.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention can be widely applied to a steel pipe structure using a steel pipe itself or a concrete-filled steel pipe as a steel column. The shape of the steel pipe column can be widely applied to a square shape, a round shape, and other shapes. The anchor bolt is not particularly limited as long as the anchor plate is embedded in the foundation concrete and can fix and fix the base plate integrally provided at the lower end of the steel pipe column using its fixing force. Is not a question. Also, the internal anchor may be anything that can be inserted and installed in the lower inside of the steel pipe column to reinforce the column base, such as a general deformed reinforcing bar or a screw reinforcing bar that has a threaded outer peripheral surface. Is possible. With regard to the installation method of the inner anchor, various installation forms such as a form in which one anchor material is installed in the lower central part of the steel pipe column, and a form in which a plurality of anchor materials are arranged around it are possible. However, it is set so as not to hinder the bar arrangement work in consideration of the relationship with other bar arrangement states in the foundation concrete. In addition, the internal anchor may be inserted into the site in advance in a factory or the like by being inserted into the lower inner side of the steel pipe column and fixed by the internal concrete. After fixing at the position and installing the steel pipe column, internal concrete may be placed inside the steel pipe column. The fixing member installed in the vicinity of the upper end of the inner anchor is one in which the fixing plate is configured integrally with the nut, or is configured separately from the nut so as to be sandwiched and supported between the upper and lower nuts. Alternatively, an appropriate form such as one using the nut itself as a fixing means is possible.
[0008]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view showing the column base portion, and FIG. 2 is a plan view. In the figure, reference numeral 1 denotes a square steel pipe column, and a base plate 2 is integrally provided at the lower end thereof by welding or the like. The peripheral portion of the base plate 2 is fastened and fixed using eight anchor bolts 3 in this embodiment. The anchor bolt 3 is embedded in the foundation concrete 4, and the upper end portion is inserted into an insertion hole 5 formed in the peripheral portion of the base plate 2. At the time of construction, after adjusting the height level and verticality of the base plate 2 using adjustment mortar and the like, the filler 6 such as grout material is filled between the base concrete 4 and solidified, and then the anchor bolt 3 is tightened with a predetermined tightening force by means of a tightening nut 7 screwed into the nut 3, and the tightened state is locked by a lock nut 8. Thereby, the steel pipe column 1 is fastened and fixed through the fixing force of the anchor bolts 3 to the foundation concrete 4. In the figure, 9 is a washer.
[0009]
Next, the characteristic part of the present invention will be described. As shown in the figure, a central opening 11 is formed in the base plate 2 in a state where an inner flange portion 10 projecting inward of the steel pipe column 1 is left. The central opening 11 may be round or other shapes in addition to the square as in the present embodiment. An inner anchor 12 is inserted and installed through the central opening 11. The lower part of the inner anchor 12 is fixed in the foundation concrete 4. A fixing member 13 is installed near the upper end of the internal anchor 12. In the present embodiment, a fixing member 13 made of a rectangular flat plate is used, and the fixing member 13 is supported by a fixing nut 14 screwed into a male screw formed on the upper portion of the internal anchor 12. With respect to the positional relationship between the fixing member 13 and the inner flange portion 10 of the base plate 2, as shown in the enlarged view of the main part of FIG. 3, the cone angle θ between the fixing member 13 and the inner anchor 12 is about 45. The cone breaking surface 15 formed of a truncated cone- shaped conical surface is at least on the inner flange portion 10 of the base plate 2, that is, the cone breaking surface 15 formed of the conical surface and the inner flange portion 10 intersect at least. Ru is set to the position relationship.
[0010]
Thus, when a tensile force F acts on the steel pipe column 1 as shown in the figure at the time of an earthquake, the pulling resistance force of the internal anchor 12 is added to the pulling resistance force of the anchor bolt 3, so that the column base is reinforced. . That is, the inner anchor 12 is mediated by the bearing pressure of the inner flange portion 10 projecting inward of the steel pipe column 1 against the inner concrete 16 and the friction force between the inner surface of the steel pipe column 1 and the outer surface of the inner anchor 12 and the inner concrete 16. Further, a pulling resistance force against the pulling force F is generated. In this case, according to the present invention, the cone breaking surface 15 is set at least in a positional relationship with respect to the inner flange 10, so that the space between the inner flange 10 and the fixing member 13, and hence the steel pipe column 1 and the inner anchor 12. It is possible to more effectively transmit the fixing force between the two. Incidentally, when the central opening 11 is large and the lower end of the cone breaking surface 15 does not cover the inner flange 10, the fixing action of the fixing member 13 does not work effectively, and the inner anchor 12 is pulled by a smaller tensile force. It will be extracted from the internal concrete 16. When a compressive force is applied to the steel pipe column 1, the compressive force is transmitted to and supported by the foundation concrete 4 via the base plate 2, and via the internal concrete 16 that is frictionally bonded to the inner surface of the steel pipe column 1. Therefore, since the central opening 11 is provided in the base plate 2, there is no decrease in yield strength. Further, even when a shearing force is applied to the steel pipe column 1, it is reinforced by the internal anchor 12.
[0011]
FIG. 4 is a longitudinal sectional view showing a column base portion of a second embodiment of the present invention. This embodiment is a modification of the first embodiment, and the cone breaking surface 1 represented by a conical surface having the fixing member 13 as a top and a cone angle θ between the fixing member 13 and the inner anchor 12 of approximately 45 degrees. When the inner width between the inner edge portions 17 of the inner collar portion 10, that is, the width of the central opening portion 11 is set slightly smaller than the cone breaking surface 15 so that 5 is slightly applied on the inner collar portion 10 of the base plate 2. It is shown. The positional relationship between the lower portion of the cone breaking surface 15 and the inner collar portion 10 is also related to the set height of the fixing member 13, that is, the inner anchor 12. This embodiment illustrates the case where the height of the fixing member 13 is set to the minimum. If the height is set higher than that including the case of the first embodiment, the internal anchors until the cone breaks. Twelve pulling resistance forces can be effectively transmitted to the steel pipe column 1. Conversely, when the height of the fixing member 13 is lower than this and the entire lower part of the cone breaking surface 15 is located in the central opening 11, the truncated cone-shaped cone portion is supported by the inner flange portion 10 of the base plate 2. Therefore, the central opening 11 is pulled out with a smaller tensile force and the cone is destroyed at an early stage.
[0012]
As described above, according to the present invention, as in the second embodiment shown in FIG. 4, the outer diameter of the fixing member 13 is d, and the inner width between the inner edge portions 17 of the inner collar portion 10, that is, the central opening. When the width of the portion 11 is B, the fixing length La of the inner anchor 12 between the inner flange portion 10 of the base plate 2 and the fixing member 13 is set to satisfy the condition of La> (Bd) / 2. Effective reinforcement for the column base is possible. Incidentally, when the inner diameter of the steel pipe column 1 is set to D and the condition of Lb = (D−d) / 2 is set as in the first embodiment shown in FIG. The lower part just reaches the inner surface of the steel pipe column 1, and the strength is high and more rational reinforcement is possible. For example, when a square steel pipe having a size of 500 × 500 × 22 mm and an inner diameter D = 456 mm is used as the steel pipe column 1 and the fixing member 13 having an outer diameter d = 80 mm is used, the fixing length Lb of the inner anchor 12 is 188 mm. If the diameter of the inner anchor 12 is set to 36 mm, it corresponds to about 5 to 6 times the diameter, so that it is necessary to take a fixing length of at least about 20 times the diameter of the anchor material. Since the fixing length Lb of the inner anchor 12 can be greatly reduced, the construction is facilitated and a very rational reinforcement work for the column base can be performed.
[0013]
FIG. 5 is a longitudinal sectional view showing an essential part of a third embodiment of the present invention. As shown in the figure, in this embodiment, the inner edge upper portion of the inner flange portion 10 of the base plate 2 is chamfered in a tapered shape to provide an inclined portion 18, thereby supporting the cone-shaped cone portion. The bearing area on the inner flange 10 side is expanded to increase the reinforcement effect on the column base of the steel pipe column 1. FIG. 6 is a longitudinal sectional view showing an essential part of a fourth embodiment of the present invention. In this embodiment, as shown in the figure, the lower portion of the outer edge of the fixing member 13 is chamfered in a tapered shape to provide an inclined portion 19, thereby supporting the truncated cone-shaped cone portion side. The bearing area is expanded to increase the reinforcing effect on the column base of the steel pipe column 1. Either one or both of these inclined portions 18 and 19 may be employed.
[0014]
7 and 8 show other types of column bases using a plurality of internal anchor members, and the present invention can also be applied to this mode . FIG. 7 is a longitudinal sectional view showing the column base, and FIG. 8 is a plan view. As shown in the figure, in this example, the case where four internal anchors 20 are installed inside the steel pipe column 1 through the central opening 11 formed in the base plate 2 is shown . In the figure, reference numeral 21 denotes a fixing member that is inserted through the upper ends of the four inner anchors 20 and fixed by nuts, and also has a function of maintaining the positional relationship between them. You may form the opening part 22 used as the passage of concrete or air at the time of the placement of the internal concrete 16 in the center part .
[0015]
【The invention's effect】
According to the present invention, the following effects can be obtained.
(1) In the invention of claim 1, a fixing member is provided in the vicinity of the upper end portion of the internal anchor installed inside the steel pipe column, and the conical angle between the fixing member and the internal anchor is approximately 45 degrees. internal cone fracture surface consisting of a truncated cone shape of the conical surface, for at least so constructed as according to the inner flange portion of the base plate, the fixing effect of the internal anchor is improved by installation of a fixing member, columnar leg portion of the steel column to It is possible to more effectively perform the reinforcing action by the anchor. Moreover, since the positional relationship between the cone breaking surface based on the fixing member provided on the internal anchor and the inner flange portion of the base plate is regulated by the positional relationship where the former cone breaking surface is at least applied to the latter inner flange portion , It is possible to rationally and accurately reduce the fixing length protruding inside the steel pipe column of the inner anchor.
(2) In the invention of claim 2, the conical surface having the apex at the center of the fixing member and the conical angle between the inner anchor and the inner anchor being approximately 45 degrees is formed by the joint between the inner flange and the steel pipe column. Since the inner anchor is installed in a state where the positional relationship between the fixing member and the inner flange portion of the base plate is maintained so as not to exceed the upper side, the length of the inner anchor can be more rationally reduced. Is possible.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a column base according to a first embodiment of the present invention.
FIG. 2 is a plan view of the same embodiment.
FIG. 3 is an enlarged view of a main part of FIG. 1;
FIG. 4 is a longitudinal sectional view showing a column base according to a second embodiment of the present invention.
FIG. 5 is a longitudinal sectional view showing an essential part of a third embodiment of the present invention.
FIG. 6 is a longitudinal sectional view showing an essential part of a fourth embodiment of the present invention.
FIG. 7 is a longitudinal sectional view showing another form of the column base.
FIG. 8 is a plan view showing the column base .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Steel pipe column, 2 ... Base plate, 3 ... Anchor bolt, 4 ... Foundation concrete, 5 ... Insertion hole, 6 ... Filling material, 7 ... Fastening nut, 8 ... Lock nut, 9 ... Washer, 10 ... Inner collar part, 11 ... central opening, 12 ... inner anchor, 13 ... fixing member, 14 ... fixing nut, 15 ... cone fracture surface, 16 ... inner concrete, 17 ... inner edge, 18, 19 ... inclined portion, 20 ... inner anchor, 21 ... Fixing member, 22 ... opening

Claims (2)

In the column base part of the steel pipe structure in which the base plate integrally provided at the lower end of the steel pipe column is fastened and fixed by anchor bolts fixed to the basic concrete, the inner flange part protruding inward of the steel pipe column is left on the base plate A central opening is formed in the state, an internal anchor is inserted into the lower inner side of the steel pipe column through the central opening, and a fixing member is installed in the vicinity of the upper end of the internal anchor. The inside of the fixing member and the base plate is arranged such that a cone breaking surface composed of a truncated cone- shaped conical surface having a cone angle between the top and the inner anchor of approximately 45 degrees is applied to at least the inner flange portion of the base plate. A reinforcing structure for a column base in a steel pipe structure, wherein the internal anchor is installed in a state in which a positional relationship with a collar portion is maintained.   The fixing member is arranged such that a conical surface having the apex at the center of the fixing member and a conical angle between the inner anchor and the inner anchor of approximately 45 degrees does not exceed the joint between the inner flange portion and the steel pipe column. The reinforcement structure of the column base part in the steel pipe structure according to claim 1, wherein the internal anchor is installed in a state in which the positional relationship with the inner flange part of the base plate is maintained.

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