JPH0458530B2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" The present invention relates to a method for fixing a steel column base.

``Prior art'' When installing steel column legs, the method of embedding the steel column legs in the beams does not fit well with the beam reinforcements. ) Since the steel frame construction takes place first, the process will be disrupted. ) Separate steel support is required during erection. For these reasons, in general, column bases for steel frame structures are constructed by burying anchor bolts in the base of a steel frame concrete structure in advance, fixing column base metal fittings with holes that loosely fit into the anchor bolts with nuts, and then fixing the column bases with nuts. Leg hardware is generally fixed and integrated with the column base by welding, bolt welding, etc.

For example, in Fig. 2, an anchor bolt 2 is buried in the foundation 1, a column base hardware 3 is placed on it, and it is fixed with a nut 4;
In the figure, each is integrated with the column base metal fittings 3 using bolts and nuts 6.

However, in this method, even if tension is applied by engaging a nut to an anchor bolt buried in concrete, there may be problems between the anchor bolt and the concrete due to the surface properties of the bolt, the properties of the concrete, etc. Due to the stable adhesion force acting on the anchor bolt, the longitudinal distribution of the tension acting on the anchor bolt is unclear, and the mechanical adhesion force is unstable. Japanese Patent Publication No. 59-5734 was published with the aim of providing a joining method that would prevent anchor bolts from loosening over time and even under the action of external forces, and ensure a highly stable fixation of column bases. has been proposed, but
The gist of this is that in a method of connecting the tip of a column pedestal of a steel frame structure to foundation concrete via an anchor member fixed to the foundation concrete, a predetermined section from the bottom of the column pedestal on the outer surface of the anchor member is fixed in the axial direction. The column base is buried and fixed in the foundation concrete in a restrained state, loosely fitted with the joint hardware fixed to the bottom of the column base, and the top of the anchor member is made to protrude, and the base of the column is placed on the base concrete, and the fastening member is attached to the top of the anchor. This method applies a predetermined tensile force to the anchor member and compressive force to the boundary between the column base metal fittings and the foundation concrete. Since the introduced tension in the predetermined length section of the anchor member is ensured, the following effects can be achieved.

(1) The clamping force of the column base by the anchor member and the fastening member can be maintained at a stable value over a long period of time.

(2) The column base has a high degree of fixation, and a stable value can be maintained even when external forces are applied, so the reliability is high.

(3) The allowable bending stress can be increased for column bases with small axial compressive force.

(4) It is possible to increase the frictional resistance of the column base force, that is, the allowable shear force.

(5) Since the anchor member shaft and concrete, which are the main cause of relaxation, are not widely attached, relaxation can be reduced in the same manner as in the conventional unbonded prestressing method.

(6) In construction management of the introduced tension, since the anchor member has a large elongation capacity, the introduced tension can be controlled by the elongation when the anchor member is tightened, that is, the rotation angle or movement distance of the tightening member. is easy.

(7) Since the shaft portion of the anchor member is long and has a large elongation capacity, the rotational capacity of the column base is increased, and the seismic energy absorption capacity of the entire structure, that is, the seismic performance can be improved.

(8) Even if repeated bending stress is applied, it can be absorbed by changes in the pressure bonding stress between the column base and the foundation.
The stress added to the anchor member is small, and fatigue failure of the anchor member can be prevented.

(9) When there are irregularities on the top surface of the leveling mortar, with the conventional type, excessive tightening force is applied to the anchor members near the protrusions, and too little tightening force is applied to the anchor members near the recesses, and the entire column base is damaged. In contrast, the method of the present invention is not affected by the unevenness of the upper surface of the leveling mortar and applies equal tension to all anchor members, which improves the degree of fixation of the column base. increasing and stable.

``Problems to be Solved by the Invention'' However, in the above-mentioned method of erecting column bases on the foundation of a reinforced concrete structure, the steel columns rest on the beams, so only the steel columns can resist stress. There will only be a section of concrete that will be poured around it.

Therefore, reinforcing bars equivalent to the steel frame will be inserted within this concrete cross section, but the fourth
As shown in the figure, the fastening member 9 attached to the upper part of the anchor member 8 of the column base hardware 7 is located outside the flange 10 at a predetermined distance for operational and stability reasons. As a result, the plate portion 9a of the column base hardware 7 had to be designed to be slightly larger than the width of the flange 10, and as a result, the reinforcing bars 11 were bent and expanded outward at the root wrap, as shown in the figure. As a result, the concrete neck 12 becomes a major design and functional bottleneck at the legs.

If this is not desired, if the tapered portion is lowered below the raised floor surface 13, the amount of earthwork and concrete work will increase, which will increase costs.

Moreover, as shown in FIG. 5, the tapered part A
If a building is built across the site boundary line 14, a portion A' will protrude from the exterior surface 15 of the building, making construction impossible.

``Means for Solving the Problems'' and ``Operations'' The present invention has been made in view of the above circumstances, and its gist is that a A steel plate with the width of the flange to which a short steel pipe for inserting an anchor bolt is welded is pasted by welding, a base plate with anchor bolt through holes is attached to the rising anchor bolt, the steel column is assembled on the base plate, and the anchor is attached. By introducing prestress into the bolt, the plate part of the column base hardware can be made smaller, eliminating the need for a large diameter neck part and improving SRC.
The advantage is that it can accommodate special shapes and dimensions of column bases.

"Example" This will be explained in detail below based on the drawings.

What is shown in FIG. 1a is a steel plate 17 to which short steel pipes 16, 16 for inserting anchor bolts are attached by welding on both sides, and the width thereof is made to match the flange width of the steel column to which it is attached.

The back side of the upper side and the front side of the lower side of the steel plate 17, short steel pipe 1
6 The lower end is beveled B for welding.

As shown in Figure b, the above-mentioned hardware is attached to the outer surface of the lower end of the flange 18a of the steel column 18 by welding and joining in the beveling process B on the back side of the upper side mentioned above, and this is buried in a predetermined position of the foundation 19 in advance. anchor bolt 20
It is attached to the base plate 21 assembled through the anchor bolt through hole drilled in the rising part of the base plate 21.

Then, it is joined to the base plate 21 by welding at the groove B on the front side of the lower side mentioned above (the welding at this time does not need to be perfect over the entire joint surface), and then by the fastening member 22. anchor bolt 2
Introduce prestress at 0.

In addition, FIG. c is a plan view of the present invention, viewing the above-mentioned hardware as a flange attached to a steel column web.

According to the configuration of the present invention described above, since the short steel pipe 16 is an unrestricted area of the anchor member with respect to concrete, the steel column 18 is pressed against the base plate 21 and the boundary with the foundation 19 is The mechanical performance when applying compressive force is the same as that of the previously mentioned Japanese Patent Publication No. 59-5734.

Furthermore, in the configuration of the present invention, the fastening member 22
Since the base plate 21 is in close contact with the flange, the size of the base plate 21 is reduced, and the above-mentioned inconvenience of the neck wrap portion is eliminated.

Incidentally, the special shape of the SRC column base is shown in FIGS. 6a, b, and c, and the S column dimension Bs is determined by the RC column dimension Bc. Although the shape and dimensions of the legs of SRC are complicated in this way, the hardware in the present invention is
As long as the width and thickness of the flange are the conditions for use as an S-column flange, it can be used regardless of the above problems.

Note that Figure A shows a general column, Figure B shows a side column, and Figure C shows a corner column. In the figures, W indicates a web and F indicates a flange.

Further, in the present invention, implementation is simplified by molding what is shown in FIG. 1a as one member and commercializing it.

Furthermore, when the object is a box-shaped column, it is convenient to surround the steel plate 17 in a box shape.

``Effects of the Invention'' As described above, according to the present invention, it is possible to design the plate portion of the column base hardware to be smaller, avoid increasing the diameter of the root wrap, and furthermore, this merit can be realized using the special features of the SRC column base. It can be enjoyed regardless of shape and size and is extremely suitable for practical use.

[Brief explanation of drawings]

Figures 1a, b, and c are overhead views, construction front views, and plan views of the hardware according to the present invention, Figures 2 and 3 are explanatory diagrams of conventional column base fixing dimensions, and Figure 4 is a conventional method. FIG. 5 is a plan view of the neck wrap portion in FIG. Explanation of symbols, 1... Foundation, 2... Anchor bolt, 3... Column base hardware, 4... Nut, 5... Column base, 6... Bolt/nut, 6'... Welding, 7...
Column base hardware, 8... Anchor member, 9... Fastening member, 9a... Plate portion, 10... Flange, 1
1... Reinforcing steel, 12... Nemaki concrete, 13...
... Floor surface, 14 ... Boundary line, 15 ... Building exterior surface, 1
6... Short steel pipe for insertion, 17... Steel plate, 18... Steel column, 18a... Flange, 19... Foundation, 20
...Anchor bolt, 21...Base plate,
22... Fastening member, A... Tapered part, A'...
Protruding part, B...beveling, Bs...S column dimensions, Bc...RC column dimensions, F...flange, W...
web.

Claims (1)

[Claims] 1. A steel plate with the width of the flange, with short steel pipes for inserting anchor bolts welded on both sides, is attached to the outer surface of the lower end of the flange of the steel column to be erected, and a base plate with anchor bolt through holes drilled therein is attached to the rising anchor. A method for fixing a steel column leg, the method comprising: assembling the base plate onto a bolt, assembling the steel column on the base plate, and applying prestress to the anchor bolt.