JP2020111936A - Method for constructing exposed-type column base - Google Patents

Abstract

To provide a method for constructing an exposed-type column base capable of properly transmitting a shearing force caused by an earthquake, wind or the like acting on a base plate in which an anchor bolt insertion hole is formed as an excessive hole to an anchor bolt, and improving the cost.SOLUTION: In a construction of an exposed-type column base in which a base plate 2 fixed to a lower end of a steel column is fixed by anchor bolts 3 projecting to an upper surface of foundation concrete 9, the anchor bolt 3 is inserted into an excessive hole 4 of the base plate 2, and fastened with two nuts 8 in a state where a nested washer 5 and a flat washer 6 composed of an upper washer and a lower washer are inserted; and when the inside of a cup-shaped container 13 is decompressed by a vacuum pump 15 in a state where the projecting part of the anchor bolt 3 is covered with the cup-shaped container 13, the inside of the excessive hole 4 of the base plate 2 becomes a vacuum state through an air flow channel 22 on an upper surface of the upper washer 20, and a grout material G is forcibly drawn in to fill a gap around the anchor bolt 3.SELECTED DRAWING: Figure 7

Description

INDUSTRIAL APPLICABILITY The present invention, in the construction of an exposed column base used in steel frame construction, etc., a space formed between the lower surface of a base plate having an excessive hole for inserting an anchor bolt and the upper surface of foundation concrete, and an excessive hole of the base plate The present invention relates to a technique for filling the grout material into the inside, and particularly to a construction method for enhancing the filling property of the grout material into the excessive hole through which the anchor bolt penetrates.

In the exposed column pedestal, anchor bolts are embedded in a predetermined position of the basic concrete leaving the upper end portion, and the base plate fixed to the lower end of the steel column is fixed to the basic concrete by a plurality of anchor bolts. Specifically, a plurality of anchor bolt insertion holes are formed in the peripheral portion of the base plate, the anchor bolts are inserted into these insertion holes, and the base plate is fixed by tightening a nut screwed through a washer. The base plate is placed on the level mortar provided on the upper surface of the basic concrete, and by pouring and filling the space formed between the upper surface of the basic concrete and the lower surface of the base plate with grout material such as non-shrink mortar, It adheres to the base concrete. In this case, the grout material may be filled into the entire lower surface of the base plate without any gap.

The anchor bolt bears tensile force and shear force as a medium for transmitting stress in the column base, and at the same time, it is required for positioning when constructing the steel frame, and therefore high accuracy is required for its installation. That is, horizontal position and verticality are important for anchor bolts. In the exposed column pedestal, the Building Standard Act stipulates that the anchor bolt insertion hole provided in the base plate must be within the anchor bolt diameter +5 mm. However, this regulation does not apply when safety is confirmed by structural calculation. Therefore, as a measure against the construction error (positional deviation) of the anchor bolt, the size of the anchor bolt insertion hole is formed to be an oversized hole that is sufficiently larger than the specified value, and the size of the outer surface of the anchor bolt that penetrates the oversized hole is too large. The method of filling the gap with the inner peripheral surface of the hole with grout material is widely used. In this construction method, it is extremely important that the grout material enters the inside of the oversized hole from the lower surface side of the base plate and fills the inside without a gap.

The conditions required for filling the grout material are the fluidity of the grout material and the injection pressure. Regarding the fluidity, an appropriate grout material is selected, and compounding is performed within a range in which required strength is obtained. The injection pressure depends on the pressure difference between the pressure of the grout material to be injected and the space of the filling destination. As a general filling method, as shown in FIG. 18, the molds 12 are installed around the base plate 2 at intervals, and the grout material G is injected from the grout container 16 to the upper end level of the base plate 2. In this case, the height difference h1 from the filling destination is the injection pressure.

As a method of obtaining a larger injection pressure, as shown in FIG. 19, the mold 12 is closely attached to the side surface of the base plate 2 to form a closed space S on the lower surface side of the base plate 2, and a sufficient amount of the grout material G is accommodated. The tip portion of the tapered grout rote 17 is vertically inserted into any of the plurality of injection holes 2a provided in the base plate 2, and the height of the grout material G is used to close the grout material G. There is a filling method of pouring into S (see Patent Documents 1 and 2). This filling method has an advantage that a sufficient injection pressure can be obtained by increasing the height h2 of the grout material G accommodated in the grout rote 17. As another filling method using the same grout rote, instead of forming the injection hole in the base plate, a specially shaped washer having an injection hole for the grout material near the anchor bolt insertion hole is used. It is also known how to do it.

Japanese Patent Laid-Open No. 2000-319990 (see FIGS. 1 to 3) JP 2000-319989 A (see FIGS. 1 to 3)

However, in the above filling method using the grout rote, the pressure in the space below the base plate surrounded by the mold in a closed state becomes high, and therefore the mold collapses (punctures) depending on the material and the assembly method of the mold. There is a possibility that Further, if the injection hole formed in the base plate is blocked by the grout material during filling and air is trapped inside the mold, there is a possibility that the flow of the grout material is obstructed and the grout material does not spread to every corner. In particular, there is a problem that the grout material is not sufficiently filled into the anchor bolt insertion hole (excessive hole) of the base plate which is a narrow space through which the anchor bolt penetrates. Further, in order to secure a sufficient injection pressure, it is necessary to use a grout material having a volume that greatly exceeds the volume of the target space, so that there is a problem that the grout material remaining in the funnel after filling is wasted.

The present invention was created in order to solve the above-mentioned problems of the prior art, and in particular, the filling property of the grout material into the excessive hole of the base plate through which the anchor bolt penetrates is enhanced, and at the time of filling the grout material, the mold It is an object of the present invention to provide a method for constructing an exposed column pedestal in which collapse is unlikely to occur and waste of grout material is reduced.

As a technical means for solving the above-mentioned problems, the invention according to claim 1 of the present application provides a plurality of anchor bolts projecting on the surface of a foundation concrete in a plurality of oversized holes of a base plate fixed to a lower end portion of a steel column, respectively. Insert the nut through the washer, tighten the nut with a washer, set the form around the base plate, and inject the grout into the inside of the form to fill the lower surface of the base plate and the large holes with the grout and form a steel column base. In the method of constructing an exposed column pedestal that is fixed on concrete, the washer has an air passage that communicates the oversized hole of the base plate with the outside, and by decompressing the inside of the oversized hole from the outside through the air passage. The feature is that the grout material is introduced into the oversized hole.

According to the above configuration, since the inside of the oversized hole of the base plate is in a vacuum state, a pressure difference occurs between the grout material and the internal space of the oversized hole even when the grout material is injected under atmospheric pressure. Due to this pressure difference, the grout material is introduced into the oversized hole, and the gap between the outer peripheral surface of the anchor bolt and the inner peripheral surface of the oversized hole can be filled in a solid state. Further, since it is not necessary to inject the grout material in a pressurized state with a height difference as in the conventional technique, the pressure load on the mold is reduced and the collapse (puncture) thereof is less likely to occur. In addition, it is economical because an extra grout material for securing the injection pressure is unnecessary. In the present invention, the vacuum state means not an absolute vacuum but a state lower than the standard atmospheric pressure.

In the structure of claim 1, the protrusion of the anchor bolt penetrating the excessive hole of the base plate is covered with a cup-shaped container, and the inside of the cup-shaped container is evacuated by a vacuum pump to reduce the pressure inside the excessive hole. (Claim 2). According to this configuration, the vacuum state inside the oversized hole is easily and surely realized, so that the grout material can be more reliably filled into the gap between the anchor bolt and the oversized hole. As another method of using a cup-shaped container, a configuration in which a plurality of cup-shaped containers are covered on the protruding portions of individual anchor bolts and a vacuum state is simultaneously established by one vacuum pump connected to a pipe communicating each cup-shaped container It is also possible (claim 3). With this configuration, it is possible to simultaneously fill the plurality of oversized holes with the grout material, which leads to an improvement in work efficiency.

With respect to the structure of claim 2 or 3, a manual vacuum pump can be used (claim 4). Since the manual vacuum pump is inexpensive and easy to operate, it is possible to realize the vacuum state of the oversized hole at the construction site with an extremely simple means, which contributes to the reduction of the construction cost. .. Further, a pressure gauge for measuring the vacuum state in the cup-shaped container may be provided (Claim 5). When the pressure gauge is provided, the vacuum state can be accurately known, which is convenient for more reliable filling work. The cup-shaped container may be made of a transparent material such as plastic. In this case, the grout material is filled up to the upper portion of the oversized hole of the base plate by ejecting the grout material from the air flow path of the washer. There is an advantage that it can be confirmed (claim 6).

In addition, the air flow path of the washer is configured as a groove portion from the inner peripheral surface that receives the anchor bolt to the outer peripheral surface (Claim 7) or a notch portion that divides at one position in the circumferential direction (Claim 7). Item 8) is preferable. According to these configurations, the air remaining in the oversized holes of the base plate is discharged to the outside through the air passages of the washers, and the inside of the oversized holes is in a vacuum state. As a result, the grout material that has flowed from the periphery of the base plate to the lower surface is introduced into the oversized hole due to the pressure difference even under the atmospheric pressure, that is, under the injection condition in which no pressure is applied. It is surely filled.

In the method for constructing the exposed column base according to the present invention, the following effects can be obtained by adopting the above configuration.
(1) Since the grout material is injected while the inside of the oversized hole of the base plate is in a vacuum state, a pressure difference is generated between the grout material and the internal space of the oversized hole even when the grout material is injected under atmospheric pressure. The pressure difference causes the grout material to be introduced (retracted) into the oversized hole, and as a result, the gap between the outer peripheral surface of the anchor bolt and the inner peripheral surface of the oversized hole can be filled with the grout material in a solid state.
(2) Instead of the conventional method of injecting the grout material under pressure using the height difference, it is not necessary to pressurize the grout material by making the inside of the excessive holes of the base plate into a vacuum state at the time of injecting the grout material. Therefore, the pressure received by the mold is reduced, and the collapse (puncture) of the mold is less likely to occur.
(3) It is economical because an extra grout material for securing the injection pressure is unnecessary.

It is a perspective view which shows the fastening state of the anchor bolt in the construction method of the exposed type column base which concerns on 1st Embodiment of this invention. (A) And (b) is a top view and sectional drawing of an upper washer which is one component of the washer (nesting washer) used by the construction method of FIG. (A)-(c) is a top view, a perspective view, and an AA sectional view of the lower washer which is the other component of the washer (nesting washer) used by the construction method of FIG. It is sectional drawing which shows the installation state of the level mortar in 1st Embodiment of this invention. FIG. 5 is a cross-sectional view showing a tightened state of anchor bolts in a steel frame erection work as the next step of FIG. 4. FIG. 6 is a plan view showing a state in which a mold is installed around the base plate as the next step of FIG. 5. It is explanatory drawing which shows the injection|pouring method of a grout material as a next process of FIG. FIG. 8 is an enlarged cross-sectional view around the excessive hole of FIG. 7. It is a sectional view showing the state where construction was completed in a 1st embodiment of the present invention. It is a BB sectional view of FIG. (A)-(c) is a modification of the nest washer used by 1st Embodiment, Comprising: It is a top view, front view, and sectional drawing of the upper washer which differs in the form of an air flow path. (A)-(c) is another modification of the nest washer used by 1st Embodiment, Comprising: It is a top view, front view, and CC sectional view of the lower washer provided with the air flow path. (A) And (b) is the top view and perspective view of the washer (flat washer) provided with the air flow path used by the construction method of the exposed type column base which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the tightening state of an anchor bolt in the construction method of the exposed type column base using the washer of FIG. (A) And (b) is the top view and perspective view of the washer (plain washer) provided with the air flow path used by the construction method of the exposure type column base which concerns on 3rd Embodiment of this invention. FIG. 16 is an enlarged cross-sectional view of the vicinity of the excessive hole in the grout material injection step in the method of constructing the exposed column base using the washer of FIG. 15. It is explanatory drawing which shows the injection|pouring method of the grout material in the construction method of the exposure type column base which concerns on 4th Embodiment of this invention. It is sectional drawing which shows the prior art example of the grout material injection method. It is sectional drawing which shows the other conventional example of the grout material injection method.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a first embodiment of a method for constructing an exposed type column pedestal according to the present invention, in which the fastening portions of some anchor bolts are disassembled to show the overall appearance. The method of injecting the grout material, which is a feature of the present invention, will be described in detail with reference to FIG. 7 after the entire structure of the exposed column base is described. In the fixing structure of the exposed type column base shown in the figure, the base plate 2 fixed to the lower end portion of the steel frame column 1 is fixed by an anchor bolt 3 protruding to the upper surface of the foundation concrete (not shown). The base plate 2 is formed with excessive holes 4 at four corners, which are larger than the nominal diameter (M12 to M80) of the anchor bolt 3 to be applied by about 22 to 50 mm. Each anchor bolt 3 is fastened with two nuts 8 in a state where a washer 7 made up of a combination of a nest washer 5 and a flat washer 6 described below is inserted.

2 and 3 show an upper washer 20 and a lower washer 30 each of which includes a pair of nest washers 5. In the upper washer 20 shown in FIG. 2, three groove portions 22 as an air flow path are radially formed on the upper surface of a disk-shaped seat portion 21 so as to extend over the inner peripheral edge and the outer peripheral edge, and the lower surface thereof is formed. The legs 23 are concentrically formed. Further, an anchor bolt receiving hole 24 having an inner diameter matching the shaft diameter of the anchor bolt 3 penetrates the seat portion 21 and the leg portion 23 at a position eccentric to the disc-shaped seat portion 21. The lower washer 30 shown in FIG. 3 has a leg portion 32 having an outer diameter adjusted to the inner diameter of the excessive hole 4 of the base plate 2 on the lower surface side of a disc-shaped seat portion 31 larger than the outer diameter of the seat portion 21 of the upper washer 20. Is formed concentrically with the seat portion 31, and the leg portion receiving hole 33 having an inner diameter that matches the outer diameter of the leg portion 23 of the upper washer 20 is eccentric to the seat portion 31 and the leg portion and the leg. It penetrates the portion 32. In the upper washer 20 and the lower washer 30, the leg washer 23 of the upper washer 20 is inserted into the leg receiving hole 33 of the lower washer 30, and the nesting washer 5 is placed in a state in which the respective seats 21 and 31 are vertically stacked. Used as.

The nest washer 5 is a member effective as means for adjusting the positional deviation of the anchor bolt 3 when the anchor bolt 3 is out of the center of the excessive hole 4. As a specific mounting method, first, the lower washer 30 is rotated to fit the leg portion 32 into the excessive hole 4 of the base plate 2. Next, the upper washer 20 is rotated (the lower washer 30 is rotated if necessary) while the upper end of the anchor bolt 3 is inserted into the anchor bolt receiving hole 24 of the upper washer 20. As a result, the upper washer 20 is fitted into the leg receiving hole 33 of the lower washer 30, and at the same time, the upper end of the anchor bolt 3 is properly inserted into the anchor bolt receiving hole 24 of the upper washer 20. In this state, as shown in FIG. 1, when the anchor bolt 3 is screwed with a double nut (or a single nut) 8, 8 to tighten the anchor bolt 3, the anchor bolt 3 receives the nest washer 5 (the upper washer 20 and the upper washer 20). With the lower washer 30), a large gap is not generated in the oversized hole 4, the positional deviation is also absorbed, and the base plate 2 is firmly fixed.

Next, a method of constructing the exposed type column base according to the first embodiment will be described with reference to FIGS. As shown in FIG. 4, by a known means such as an anchor frame, a plurality of anchor bolts 3 are installed in a predetermined position of the foundation concrete 9 in a protruding state, and after the foundation concrete 9 is hardened, the template 10 is removed and leveled. The mortar 11 is laid in an appropriate place.

As the subsequent steel erection work, as shown in FIG. 5, while inserting the anchor bolt 3 into the excessive hole 4 for inserting the anchor bolt of the base plate 2 fixed to the lower end of the steel column 1, the level mortar 11 The base plate 2 is placed on top and the position is adjusted in the horizontal direction. Further, the upper washer 20 and the lower washer 30 constituting the nesting washer 5 are fitted into the anchor bolt 3 and rotated in an appropriate direction according to the positional deviation of the anchor bolt 3 so that the lower washer 4 is inserted into the excessive hole 4 of the base plate 2. The leg portion 32 of the washer 30 is fitted. Further, after the plain washer 6 is placed on the upper surface of the upper washer 20, it is fastened with the two nuts 8 and 8.

FIG. 6 is a plan view showing a state in which a mold is installed around the base plate 2 as the next step of the steel frame erection work of FIG. The form frame 12 is erected in a rectangular shape with a space of, for example, 50 mm from the base plate 2.

Next, as shown in FIG. 7, the protruding portion of the anchor bolt 3 including the nest washer 5 and the plain washer 6 is covered with a cup-shaped container 13 made of a transparent resin such as acrylic resin, and the upper surface of the base plate 2 is covered. The cup-shaped container 13 is placed so that the opening-side end surface of the cup-shaped container 13 is in close contact with. One end side of the plastic tube 14 is connected to the bottom surface portion 13a of the cup-shaped container 13, and a manual vacuum pump 15 is connected to the other end side of the plastic tube 14. Then, after slowly pouring the grout material G such as non-shrink mortar contained in the grout container 16 from the outer side of the base plate 2 to the upper end position of the mold 12, the vacuum pump 15 is operated. Note that glass or the like can be used as the material of the cup-shaped container 13.

FIG. 8 is an enlarged cross-sectional view of the vicinity of the excessive hole of FIG. 7. When the inside of the cup-shaped container 13 is evacuated by the operation of the vacuum pump 15, the air staying in the oversized hole 4 of the base plate 2 moves upward through the gap between the inner peripheral surface of the insert washer 5 and the outer peripheral surface of the anchor bolt 3. And is further drawn toward the cup-shaped container 13 through three groove portions 22 (air flow paths) formed on the upper surface of the upper washer 20. As a result, the inside of the oversized hole 4 is also in a vacuum state, so that the grout material G that fills the gap between the lower surface of the base plate 2 and the base concrete 9 is further forcibly drawn into the oversized hole 4 of the base plate 2 and nested. The space below the washer 5 can be raised to reliably fill the inside. The operation using the cup-shaped container 13 and the vacuum pump 15 is performed on each anchor bolt 3.

In the above-described embodiment, since the cup-shaped container 13 is transparent, when the grout material G is ejected from the groove 22 formed on the upper surface of the upper washer 20 in association with the suction operation, It can be confirmed that the grout material G is sufficiently filled up to the upper portion. However, it is also assumed that the grout material G does not jet even if the flow passage has a sufficient cross-sectional area. In that case, the filling state of the grout material G can be confirmed by adjusting the degree of vacuum and the size of the air flow path.

9 and 10 are cross-sectional views showing a construction completed state in which the injected grout material G is hardened and the mold 12 is removed in the construction method for the exposed mold column base according to the first embodiment of the present invention, and BB. FIG. As shown in the figure, the grout material G reaches the lower surface of the leg portion 32 of the insert washer 5 in the excessive hole 4 of the base plate 2. As a result, the gap around the anchor bolt 3 is reliably filled with the grout material G in the excessive hole 4 of the base plate 2.

11(a) to 11(c) are modified examples of the nest washers used in the first embodiment. In the nest washers similar to the above embodiment, the air flow path is different from that of FIG. It is the top view, front view, and sectional view of a washer. The lower washer in this case uses the one shown in FIG. The illustrated upper washer 40 is similar to that of FIG. 2 in that the leg portions 42 are concentrically provided on the lower surface of the seat portion 41, but one groove portion 43 is formed in the narrowest position of the seat portion 41. The groove 43 opens into an annular inclined surface 45 formed at the upper end of the anchor bolt receiving hole 44, and the groove 43 and the annular inclined surface 45 constitute an air flow path.

12(a) to 12(c) show another modification of the insert washer used in the first embodiment, which is also the same as the insert washer of the above-described embodiment, except that the lower washer having an air flow path is provided. It is a top view, a front view, and a sectional view. The lower washer 50 shown in the drawing is common to that of FIG. 3 in that the leg portion 52 is concentrically provided on the lower surface of the seat portion 51. In this case, the air flow path has an axial longitudinal groove 53 formed on the outer peripheral surface of the leg portion 52 of the lower washer 50, one end side of the lower surface of the seat portion 51 is continuous with the vertical groove 53, and the other end side of the air passage is seated. The lateral groove 54 is formed in the radial direction and opens on the outer peripheral surface of the portion 51. Three air passages are provided radially around the leg receiving hole 55. In the upper washers 20 and 40 and the lower washer 50 described above, the groove preferably has a width of 2 mm and a depth of 1 mm or more. In addition, in the method of constructing an exposed column base according to the present invention, when a nested washer having an air flow path is used, it is not essential to provide a plain washer between the upper washer and the nut.

13(a) and 13(b) are a plan view and a perspective view of a flat washer used in combination with a telescopic washer in the second embodiment of the present invention, and FIG. 14 is a construction of an exposed column base using the flat washer. In the method, it is a perspective view showing the entire appearance by disassembling some fastening parts of the anchor bolts. The flat washer 60 has a substantially C-shaped configuration in which an annular washer body 61 is divided at one position in the circumferential direction, and the cutout portion 62 functions as an air flow path. As shown in FIG. 14, the flat washer 60 is used by stacking it on the upper surface side of a normal nesting washer 16 in which neither the upper washer 14 nor the lower washer 15 is formed with air venting means such as grooves. Although not shown, a step of covering the protruding portion of the anchor bolt 3 with the cup-shaped container 13 and slowly pouring the grout material G from the outside of the base plate 2 to the upper end position of the mold 12 and then operating the vacuum pump 15. Regarding the above, it is the same as the construction method according to the first embodiment. In this case, the air staying in the internal space of the oversized hole 4 of the base plate 2 passes through the gap between the inner peripheral surface of the anchor bolt receiving hole 14 a of the upper washer 14 and the outer peripheral surface of the anchor bolt 3, and the flat washer 60 It moves from the notch 62 (air passage) into the cup-shaped container 13.

15(a) and 15(b) are a plan view and a perspective view of a plain washer used in the third embodiment of the present invention, and FIG. 16 shows a method of constructing an exposed column base using the plain washer. It is sectional drawing which expanded the periphery of the excessive hole in the injection process of a grout material. This 3rd Embodiment is an example which does not use a nest washer. In the illustrated flat washer 70, three groove portions 72 (air flow paths) are radially formed on one surface of an annular washer body 71 so as to extend over the inner peripheral edge and the outer peripheral edge. Then, as shown in FIG. 16, the plain washer 70 is inserted into the anchor bolt 3 so that the groove portion 72 is located on the upper surface, and further the ordinary plain washer 6 is fastened with the two nuts 8 and 8 in a stacked state. ing.

FIG. 17: is explanatory drawing which shows the injection|pouring method of the grout material in the construction method of the exposure type column base which concerns on 4th Embodiment of this invention. The fourth embodiment is characterized in that the grout material G can be simultaneously filled in the plurality of large holes 4 of the base plate 2. In the drawing, a column base of four anchor bolts is shown as an example. That is, in the fourth embodiment, the other ends of the plastic tubes 14 connected to the four cup-shaped containers 13 (only two on the front side are shown in the drawing) are connected to the manifold 80, respectively. 80 and a manual vacuum pump 15 are connected via a plastic tube 14. Further, a pressure gauge 81 is attached to the manifold 80.

In the fourth embodiment described above, when the grout material G such as non-shrink mortar contained in the grout container 16 is slowly poured from the outside of the base plate 2 to the upper end position of the form 12, the vacuum pump 15 is operated. The inside of the four cup-shaped containers 13 is in a vacuum state, and the air staying in the oversized holes 4 of the base plate 2 is the inner peripheral surface of the insert washer 5 (the upper washer 20 and the lower washer 30) and the outer periphery of the anchor bolt 3. It moves upward in the gap with the surface, and further passes through the three groove portions 22 (air flow paths) formed in the upper surface of the upper washer 20 and is drawn into the cup-shaped container 13. As a result, the insides of all the oversized holes 4 are also brought into a vacuum state at the same time, so that the grout material G that fills the gap between the lower surface of the base plate 2 and the foundation concrete 9 is forcibly drawn into each of the oversized holes 4 ( Introduced), the space below the nesting washer 5 can be raised to fill each internal space at the same time. In this case, the vacuum state can be accurately known by the pressure gauge 81, which is convenient for more reliable filling work.

It should be noted that the present invention is not limited to the above-described embodiment, and when an air passage is provided in the nest washer, it may be formed in at least one of the upper and lower washers, but it is also possible to provide it in both. Is. Furthermore, various modifications can be made within the technical concept of the present invention, such as changing the shape and number of air passages, changing the installation location, changing the vacuum pump, or connecting the vacuum pump to the washer without using a cup-shaped container. It is possible.

The method of constructing an exposed column pedestal according to the present invention exhibits its superiority when used in a building such as a steel frame structure, and is further developed as a means for improving the seismic performance of the structural frame, workability, and economic efficiency. There is expected.

DESCRIPTION OF SYMBOLS 1... Steel column, 2... Base plate, 2a... Injection hole, 3... Anchor bolt, 4... Excessive hole, 5,16... Nesting washer, 6,60, 70... Plain washer, 7... Washer, 8... Nut, 9... Basic concrete, 10... Template, 11... Level mortar, 12... Formwork, 13... Cup-shaped container, 14... Plastic tube, 15... Vacuum pump, 16... Grout container, 17... Groutlot, 20, 40... Top washer, 30, 50... Lower washer 21, 31, 41, 51... Seat portion, 23, 32, 42, 52... Leg portion, 24, 44... Anchor bolt receiving hole, 22, 43, 53, 54... Groove portion (air flow ), 33, 55... Leg receiving holes, 62... Notch (air flow path), 80... Manifold, 81... Pressure gauge, G... Grout material

As a technical means for solving the above-mentioned problems, the invention according to claim 1 of the present application provides a plurality of anchor bolts projecting on the surface of a foundation concrete in a plurality of oversized holes of a base plate fixed to a lower end portion of a steel column, respectively. Insert the nut through the washer on the top side of the base plate, tighten the nut with a washer, install the formwork around the base plate with a gap, and inject grout material inside the formwork to grout the bottom surface of the base plate and the oversized holes. In the construction method of the exposed type column base that is filled with material and fixed the steel column on the foundation concrete, the washer has an air passage communicating with the excessive hole of the base plate and the outside, and from the outside through the air passage. The feature is that a structure is adopted in which the grout material is introduced from the lower surface side of the base plate into the inside of the excessive hole by reducing the pressure inside the excessive hole.

According to the above configuration, since the inside of the oversized hole of the base plate is in a vacuum state, when the grout material is injected under atmospheric pressure , that is , even when the space between the side surface of the base plate and the mold is open , the oversized hole is formed. There is a pressure difference with the internal space of the. Due to this pressure difference, the grout material is introduced into the oversized hole, and the gap between the outer peripheral surface of the anchor bolt and the inner peripheral surface of the oversized hole can be filled in a solid state. Further, since it is not necessary to inject the grout material in a pressurized state with a height difference as in the conventional technique, the pressure load on the mold is reduced and the collapse (puncture) thereof is less likely to occur. In addition, it is economical because an extra grout material for securing the injection pressure is unnecessary. In the present invention, the vacuum state means not an absolute vacuum but a state lower than the standard atmospheric pressure.

In the method for constructing the exposed column base according to the present invention, the following effects can be obtained by adopting the above configuration.
(1) When the grout material is injected under atmospheric pressure because the inside of the oversized hole of the base plate is vacuumed, even when the grout material is injected under atmospheric pressure, that is, even when the side surface of the base plate and the form are open. A pressure difference occurs between the inner space of the oversized hole and the inner space. The pressure difference causes the grout material to be introduced (retracted) into the oversized hole, and as a result, the gap between the outer peripheral surface of the anchor bolt and the inner peripheral surface of the oversized hole can be filled with the grout material in a solid state.
(2) Instead of the conventional method of injecting the grout material under pressure using the height difference, it is not necessary to pressurize the grout material by making the inside of the excessive holes of the base plate into a vacuum state at the time of injecting the grout material. Therefore, the pressure received by the mold is reduced, and the collapse (puncture) of the mold is less likely to occur.
(3) It is economical because an extra grout material for securing the injection pressure is unnecessary.

FIG. 6 is a plan view showing a state in which a mold is installed around the base plate 2 as the next step of the steel frame erection work of FIG. On each side surface of the rectangular base plate 2, the form 12 is erected in a rectangular shape with an interval of 50 mm, for example.

Next, as shown in FIG. 7, the protruding portion of the anchor bolt 3 including the nest washer 5 and the plain washer 6 is covered with a cup-shaped container 13 made of a transparent resin such as acrylic resin, and the upper surface of the base plate 2 is covered. The cup-shaped container 13 is placed so that the opening-side end surface of the cup-shaped container 13 is in close contact with. One end side of the plastic tube 14 is connected to the bottom surface portion 13a of the cup-shaped container 13, and a manual vacuum pump 15 is connected to the other end side of the plastic tube 14. Then, after slowly pouring the grout material G such as non-shrink mortar contained in the grout container 16 from the outer side (periphery) of the base plate 2 to the upper end position of the mold 12, the vacuum pump 15 is operated. Note that glass or the like can be used as the material of the cup-shaped container 13.

FIG. 8 is an enlarged cross-sectional view of the vicinity of the excessive hole of FIG. 7. When the inside of the cup-shaped container 13 is evacuated by the operation of the vacuum pump 15, the air staying in the oversized hole 4 of the base plate 2 moves upward through the gap between the inner peripheral surface of the insert washer 5 and the outer peripheral surface of the anchor bolt 3. And is further drawn toward the cup-shaped container 13 through three groove portions 22 (air flow paths) formed on the upper surface of the upper washer 20. Thus, also becomes a vacuum state inside the excessive holes 4, forcing the inner portion of the grout G filled with gaps, excessive holes 4 further from the lower surface side of the base plate 2 and the lower surface and the foundation concrete 9 of the base plate 2 The space below the nest washer 5 can be lifted up and the inside can be reliably filled. The operation using the cup-shaped container 13 and the vacuum pump 15 is performed on each anchor bolt 3.

13(a) and 13(b) are a plan view and a perspective view of a flat washer used in combination with a telescopic washer in the second embodiment of the present invention, and FIG. 14 is a construction of an exposed column base using the flat washer. In the method, it is a perspective view showing the entire appearance by disassembling some fastening parts of the anchor bolts. The flat washer 60 has a substantially C-shaped configuration in which an annular washer body 61 is divided at one position in the circumferential direction, and the cutout portion 62 functions as an air flow path. As shown in FIG. 14, the flat washer 60 is used by stacking it on the upper surface side of a normal nesting washer 16 in which neither the upper washer 14 nor the lower washer 15 is formed with air venting means such as grooves. Although not shown, the protruding portion of the anchor bolt 3 is covered with the cup-shaped container 13, the grout material G is slowly poured from the outer side (around) of the base plate 2 to the upper end position of the form 12, and then the vacuum pump 15 is attached. The step of operating is the same as the construction method according to the first embodiment. In this case, the air staying in the internal space of the oversized hole 4 of the base plate 2 passes through the gap between the inner peripheral surface of the anchor bolt receiving hole 14 a of the upper washer 14 and the outer peripheral surface of the anchor bolt 3, and the flat washer 60 It moves from the notch 62 (air passage) into the cup-shaped container 13.

In the fourth embodiment, the grout material G such as non-shrink mortar contained in the grout container 16 is slowly poured from the outside (around) the base plate 2 to the upper end position of the mold 12, and then the vacuum pump 15 is turned on. When operated, the insides of the four cup-shaped containers 13 are brought into a vacuum state, and the air staying in the excessive holes 4 of the base plate 2 is retained by the inner peripheral surface of the insert washer 5 (the upper washer 20 and the lower washer 30) and the anchor bolt. It moves upward in the gap with the outer peripheral surface of the metal plate 3, and further passes through the three groove portions 22 (air flow paths) formed on the upper surface of the upper washer 20 and is drawn into the cup-shaped container 13. As a result, the insides of all the oversized holes 4 are also brought into a vacuum state at the same time, so that the grout material G that fills the gap between the lower surface of the base plate 2 and the foundation concrete 9 is forcibly drawn into each of the oversized holes 4 ( Introduced), the space below the nesting washer 5 can be raised to fill each internal space at the same time. In this case, the vacuum state can be accurately known by the pressure gauge 81, which is convenient for more reliable filling work.

Claims (8)

Insert a plurality of anchor bolts projecting on the surface of the foundation concrete into a plurality of oversized holes of the base plate fixed to the lower end of the steel column, tighten them with nuts through washers, and install a formwork around the base plate. Then, in the construction method of the exposed mold column base, wherein the grout material is filled into the lower surface and the excessive holes of the base plate by injecting the grout material into the inside of the formwork, and the steel column is fixed onto the foundation concrete. Has an air flow path communicating with the oversized hole of the base plate and the outside, and introduces the grout material into the oversized hole by depressurizing the inside of the oversized hole from the outside through the air flow path. A method of constructing an exposed column base, which is characterized in that The method for constructing an exposed column base according to claim 1, wherein the protruding portion of the anchor bolt is covered with a cup-shaped container, and the inside of the cup-shaped container is evacuated by a vacuum pump to reduce the pressure inside the excessive hole. The method of constructing an exposed column base according to claim 2, wherein a plurality of the cup-shaped containers are covered with respective anchor bolts, and a single vacuum pump connected to a pipe communicating the cup-shaped containers simultaneously makes a vacuum state. The method for constructing an exposed column base according to claim 2, wherein the vacuum pump is a manual type. The method for constructing an exposed column base according to claim 2, further comprising a pressure gauge for measuring a vacuum state of the cup-shaped container. The method for constructing an exposed column base according to claim 2, wherein the cup-shaped container is made of a transparent material. The method for constructing an exposed column base according to any one of claims 1 to 6, wherein the air flow path of the washer is a groove portion that extends from an inner peripheral surface that receives the anchor bolt to an outer peripheral surface. 7. The method for constructing an exposed column base according to claim 1, wherein the air flow path of the washer is a cutout portion that divides at one location in the circumferential direction.

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