JPH0347343A - Column base metal body and tight-connecting method for steel column base therewith - Google Patents

Abstract

PURPOSE:To largely improve resistivity against shearing stress by applying tension to anchor bolts that are made to penetrate into a hollow, box-shaped column base metal body, and by dispersedly transmitting the tension to the whole area of bearing surface of a concrete foundation. CONSTITUTION:A hollow, box-shaped column base metal body 2, made of cast iron with its upper side opened, is formed of a bottom board 5 to which anchor bolt holes 9 and 9 are bored, a protruding part 7 that is provided thereon and ribs 6, 6 and 8. A steel column base 15 is connected by butt welding to the protruding part 7 of the column base metal body 2 and the anchor bolt holes 9 and 9 of the base board 5 are penetrated with anchor bolts 17 and 17 planted to a concrete foundation 16. Then upper steel plates 3 and 3 are fit to the anchor bolts 17 and 17 being supported with the upper ends of the ribs 6, 6 and 8, and tension is applied to the anchor bolts 17 and 17. With the dispersedly transmitted to the bearing surface of the concrete foundation through the upper steel plates 3 and 3, ribs 6, 6 and 8 and the bottom board 5, the steel column base 15 is tightly connected to the concrete foundation.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a column base metal fitting used when building a steel column of a civil engineering building structure on a concrete foundation, and a column base metal fitting used when building a steel column of a civil engineering building structure on a concrete base. This article relates to a method for crimping and bonding column bases to the top.

(Prior art) Conventionally, when building steel columns for civil engineering and architectural structures on concrete foundations, the columns are connected to the concrete foundation via column base hardware, and the axial compressive force, bending moment, and shear force generated in the columns are reduced. These stresses are transmitted to the concrete foundation. Conventionally, as column base metal fittings for such construction methods, for example, one that has a protrusion that matches the cross-sectional shape of the column on the bottom plate, a protrusion on the bottom surface, and is integrally formed by casting (Special Publication No. 52-
4413) is known. By having projections on the bottom surface of the column base hardware, the horizontal resistance force of the bottom surface is increased, and the force of transmitting the shear force acting on the column to the concrete base is increased. In addition, as other pillar base metal fittings, a pedestal with a part protruding from the bottom plate is provided around the anchor bolt fitting holes formed at the four corners of the bottom plate, and the bottom of the pedestal is provided above the bottom plate, and the base plate is placed above the bottom plate. In addition to increasing the resistance of the anchor bolt to the applied bending moment, the diameter of the anchor bolt fitting hole is increased to prevent the anchor bolt embedded in the concrete foundation from fitting if the axis of the hole is misaligned. The matching hole is adjusted with an eccentric washer, etc. (Japanese Patent Laid-Open No. 62-29603)
Publication No. 5), etc. are known.

(Problems to be Solved by the Invention) The above-mentioned conventional footnote hardware is used to connect the column base to the concrete base by bolting using anchor bolts. However, if the joint is simply bolted, sufficient surface contact between the bottom surface of the column base hardware and the concrete base surface cannot be obtained, and the shear force acting on the column may cause the joint surface to slip, or There is a drawback that a sufficient connection between the base plate and the concrete base cannot be obtained because the bottom plate curves due to the bending moment. In order to eliminate this drawback, each of the above conventional examples attempts to improve resistance to shear force or bending moment by the above-mentioned means, but the resistance to shear force and bending moment is simultaneously improved. That was difficult. The surest way to improve the resistance to shearing force and bending moment is to increase the weight of the column base hardware to increase its rigidity, but this increases the material cost of the column base hardware and increases the cost. There are problems that make construction difficult. In addition, with conventional column base metal fittings, the installation of anchor bolts fixed to the concrete foundation has small tolerances, and a slight deviation in the anchor bolt position may cause the column base metal fittings to be installed without aligning with the bolt holes of the column base metal fittings. was difficult. Said Japanese Unexamined Patent Publication No. 6
2-296035, in order to solve this problem, the bolt holes are enlarged and adjustments are made using washers that fit into the bolt holes. However, there are problems such as the construction is troublesome.

The present invention was devised in view of the above-mentioned circumstances, and it is possible to increase the load diffusion area to obtain strong surface contact, increase the rigidity without increasing the weight, and reduce the weight of column base hardware. The purpose of the present invention is to provide a column base metal fitting that can be easily assembled on site, and also provide a method for constructing the same.

(Means for solving the problem) The stresses generated in the column are mainly compressive force, bending moment, and shear force in the axial direction. In order to resist these stresses and support the column base metal fittings on the concrete base, it is ideal that the column base metal fittings and the concrete base be in a rigidly connected state. From this point of view, it is extremely effective to apply tension to the anchor bolts and press-bond the column base metal fittings and concrete by prestressing, but the rigidity of the column base metal parts must be sufficiently high to fully demonstrate this effect. In addition, it is desirable to spread the tension force of the anchor bolt more widely on the concrete bearing surface and transmit it.

The present invention solves the above problems by finding the following means that reduces the weight of the column base hardware compared to the conventional one and satisfies the above conditions.

That is, the column base hardware of the present invention for solving the above-mentioned problems includes: a bottom plate in which anchor bolt holes are provided; a protrusion provided on the top surface of the bottom plate to which a steel column base is fixed; A column base metal body integrally formed of cast steel with a hollow box shape with an open top formed by a rib protruding from the top surface of the bottom plate located around the protrusion, and an upper part having an anchor bolt hole. It has a structure characterized by being combined with a steel plate.

In addition, the crimping method for joining steel column bases using the column base hardware includes a bottom plate with anchor bolt holes, a protrusion provided on the top surface of the bottom plate to which the steel column base is fixed, and the protrusion The steel column base is butted against the protrusion of the column base metal body, which is integrally formed of cast steel and has a hollow box shape with an open top with ribs protruding from the upper surface of the bottom plate so as to be located around the periphery of the base plate. Weld the anchor bolts installed on the concrete base through the anchor bolt holes of the bottom plate, fit the upper steel plate with the anchor bolt holes into the anchor bolts, and support the upper ends of the ribs. This is a construction method characterized by introducing tension force into the concrete base, dispersively transmitting the tension force to the bearing surface of the concrete base via the upper steel plate, ribs and bottom plate, and crimping and joining the steel column base to the concrete base.

(Function) Since the column base hardware of the present invention has a box-shaped structure with ribs, the tension introduced into the anchor bolt is transmitted to the concrete surface by the nut, as schematically shown in Fig. 3. (
washer) 11 to the upper steel plate 3 as compressive force,
It is transmitted to the bottom plate 5 through the entire cross section of the rib 6.8, and is transmitted to the concrete base with a spread from that cross section,
Generates compressive stress with the cocrete base, resulting in strong surface contact. In the figure, the hatched part S represents the stress transmission area. On the other hand, since all of the above-mentioned conventional column base metal fittings have a thick plate structure made of cast steel, even if tension force is introduced into the column base metal fittings by the anchor bolts 21, the stress is not transmitted to the concrete base as shown in Fig. 4. In this case, it is transmitted only through a portion S2 which extends conically from the surface of the thick plate 2° with which the nut 22 comes into contact. Therefore, the column base metal fittings of the present invention are lighter in weight than those of conventional thick plate structures, but they efficiently transmit the tension force of anchor bolts to the concrete bearing surface through the column base metal fittings, which is close to a rigid connection. Bonding is obtained, frictional resistance is improved, and resistance to shearing forces is dramatically improved.

Furthermore, since the column base hardware has a box-like cross-sectional shape, the rigidity per weight is increased compared to a structure made of just one thick plate. Therefore, deformation due to one bending moment can be suppressed without increasing the thickness of the bottom plate.

In terms of construction, since the upper steel plate is independent from the hardware body, it can be fitted to the anchor bolt freely, and the anchor bolt can be installed with a certain degree of intersection and 1.
It requires less assembly time and the column base hardware is lightweight, making construction easy.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows an embodiment of the column base hardware according to the present invention. In the figure, reference numeral 1 denotes a column base metal fitting, which is composed of a column base metal body 2 integrally formed of cast steel and a plurality of upper steel plates 3. The column base hardware main body 2 includes a flat bottom plate 5, a circumferential wall rib 6 with an open top that stands up from the four circumferences of the top surface of the bottom plate,
It has a hollow box-like integral shape consisting of a protrusion 7 for butt welding a steel column 15 erected within the circumferential rib, and an internal rib 8 provided between the protrusion and the circumferential rib. The bottom plate 5 has an anchor bolt hole 9 (see Fig. 2) located at the middle bottom of the square section divided by the ribs.
The diameter of the hole is sufficiently larger than the diameter of the anchor bolt (approximately +20 m), so that even if the installation position of the anchor bolt is slightly off, the column base hardware can be fitted easily. It has become. The protruding portion 7 has a cross-sectional shape that corresponds to the cross-sectional shape of the steel column 15, and in the illustrated example, it has a box-shaped cross-section.
In the case of a shaped steel frame, the cross section of the protrusion should be made into a ■ shape accordingly.

The water column hardware has the above-mentioned structure, and its construction method is to butt weld and join the steel column 15 to the tip of the protrusion 7 at a factory or construction site, and then connect it to the concrete base 16 through the bolt hole 9 of the bottom plate 5. The steel column 15 is erected and leveled on the concrete base through the installed anchor bolt 17, and the upper steel plate 3 is fitted to the anchor bolt 17 and supported on the top of the rib 6.8, and the washer 10 Temporarily tighten with nuts 11 through the cement foundation 1.
Grout 18 is injected between 6 and the bottom plate.

Thereafter, a tension force is introduced into the anchor bolt by an appropriate means such as a hydraulic jack, and the column base hardware 1 and the concrete foundation are pressure-welded and integrated. After construction, the column base hardware may remain exposed from the concrete base, or if necessary, it may be buried in the concrete by pouring dirt floor concrete or protective concrete. In addition, in order to introduce tension force into the anchor bolt, a PCS bar anchor bolt is used.

In this embodiment, as described above, the bolt hole 9 of the bottom plate 5 is a loose hole with a large diameter, so that the anchor bolt 17 can be fitted easily even if the anchor bolt is slightly misaligned. be able to. The bolt holes in the upper steel plate have no play, but the upper steel plate is in a state where it can be freely fitted to each anchor bolt, so
It can be fitted easily regardless of the position of the anchor bolt. In particular, since this construction method is a crimping method using prestress, the shear force acting on the column is handled by the frictional force between the bottom of the column base hardware and the concrete surface, which requires strict fitting of the anchor bolt and bolt hole. There is no need to do this at all, and the positioning accuracy of the anchor bolt can be relaxed as described above.

(Effects) The present invention includes one or more configurations, and provides the following special effects.

Since the column base hardware has a box-like structure with ribs, the tension force introduced into the anchor bolt is transmitted to the concrete foundation through the entire rib cross section to the bottom plate. As a result, the column base hardware of the present invention has a wider stress diffusion area than the conventional one having a single thick plate structure, improves frictional resistance, and dramatically improves resistance to shearing force.

In addition, the rigidity per weight is dramatically increased compared to conventional products, and deformation due to bending moments can be suppressed. Therefore, it has become possible to reduce the weight of the pillar base hardware.

In terms of construction, since the upper mesh plate is independent from the hardware body, it can be fitted to the anchor bolts freely, and the anchor bolts can be installed with a certain degree of intersection.
Since it is integrally made of cast steel with ribs, there is no need to weld the ribs on site, reducing assembly man-hours. Furthermore, the column base hardware is also lightweight, making it easy to install.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an embodiment of the column base hardware according to the present invention;
The figure is a side view including a partial cross section in the construction state, and Figure 3 (
a) and (b) are explanatory diagrams showing the tension force transmission mechanism using the crimp joint method for steel frame column bases of the present invention, and Figures 4 (a) and (b) show the tension when tension force is introduced into the conventional column base metal fittings. It is an explanatory view showing a force transmission mechanism. 1: Column base hardware 2: Column base hardware 3: Upper steel plate
5: Bottom plate 6: Peripheral rib 7: Protrusion 8: Internal rib 9: Anchor bolt hole 15: Steel column
16: Concrete base 17: Anchor bolt Figure 1 Figure 2 Calculation Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1) A bottom plate in which anchor bolt holes are provided, a protrusion provided on the upper surface of the bottom plate to which the steel column base is joined, and a It is characterized by a combination of a column base metal body which is integrally formed of cast steel and has a hollow box shape with an open top with ribs protruding from the top surface of the bottom plate, and an upper steel plate having anchor bolt holes. Column base hardware. 2) A bottom plate provided with anchor bolt holes, a protrusion provided on the top surface of the bottom plate to which the steel column leg is fixed, and a protrusion protruding from the top surface of the bottom plate located around the protrusion. A steel column base is butt welded to the protrusion of the column base metal body, which is integrally formed of cast steel and has a hollow box shape with an open top with ribs, and is installed on the concrete base in the anchor bolt hole of the bottom plate. An upper steel plate having an anchor bolt hole is fitted into the anchor bolt and supported by the upper end of the rib, and a tension force is introduced into the anchor bolt, and the tension force is applied to the upper steel plate. A method for crimping and joining a steel column base, characterized by crimping and joining the steel column base to a concrete base by dispersively transmitting pressure to the bearing surface of the concrete base via ribs and a bottom plate.