JP2019035313A - Washer for exposure type column base and anchorage structure of exposure type column base using the same - Google Patents

Abstract

To provide a washer for an exposure type column base abd an anchorage structure of a column base for improving an earthquake performance of the column base by a better filling of a grout material.SOLUTION: A washer is arranged between a nut 11 threading into an anchor bolt 10 and a base plate 14 and in a condition in which the base plate 14 is anchored on a base concrete 13 by a clumping of the nut 11 and used for an exposure type column base anchoring a steel column on a base concrete by filling a grout material G in a gap generated between an upper surface of the base concrete 13 and a lower surface of the base plate 14 and in a gap generated between an inner peripheral surface of a bolt hole 14a of the base plate 14 and an outer peripheral surface of an anchor bolt 10 respectively and three air discharge grooves 4a, 4b and 4c for non leaking the grout material G are arranged from an insertion hole 3 of the anchor bolt 10 in the radially outward direction with a length exposing beyond an outer peripheral edge of the nut 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a grout material injection technique that contributes to the improvement of the seismic performance of exposed column bases installed in steel structures such as ramen structures and brace combined ramen structures. The present invention relates to a washer installed between a fastening nut and a base plate to be joined, and a fixing structure of an exposed column base using the washer.

  The column base of the steel structure is tightly joined to the foundation structure (foundation concrete) by a plurality of anchor bolts. If an anchor bolt breaks during an earthquake, etc., it will result in the destruction of the column base and further the collapse of the building. For this reason, the column base is an important joint for the building.

  The types of connection between the column bases using anchor bolts and the foundation concrete are roughly classified into exposed column bases and non-exposed type column bases (embedded column bases, root winding column bases, etc.). Types of stress applied to the column base due to an earthquake or the like include an axial force, a bending moment, and a shearing force, and the column base joint member and the building structure body are designed to be safe against these stresses. In the exposed column base, the axial force, bending moment and shear force are borne by the anchor bolt. On the other hand, the non-exposed type column base is designed to load other structural members such as reinforcing bars and concrete without burdening the anchor bolt with a shearing force. For this reason, anchor bolts used in exposed column bases have a greater role in stress burden due to seismic force, etc. than non-exposed column bases, and require safer and more careful design. . In particular, sufficient consideration is necessary for dealing with shearing force.

  Therefore, the gap between the lower surface of the base plate fixed to the lower end of the steel column and the upper surface of the foundation concrete in which the lower side of the anchor bolt is embedded, and the gap between the bolt hole and the anchor bolt formed as an excessive hole in the periphery of the base plate A technology is widely used in which a grout material (non-shrinking mortar) is filled and solidified to integrate the column base with the foundation. In this conventional technology, the base plate and the base concrete are brought into close contact with each other through the grout material, and shear force is transmitted by the frictional resistance. The anchor bolt and the base plate are integrated by a relatively simple operation of injecting the grout material. It is excellent in that it can be realized reliably and a solid column base structure can be obtained.

  As a specific filling method of the grout material, after the base plate is installed on the foundation concrete, the base plate is surrounded by a mold material (dam plate), and the liquid grout material is placed from the appropriate injection hole to the lower surface side of the base plate. The gap between the entire bottom surface of the base plate and the bolt hole of the base plate through which the anchor bolt is inserted is filled while discharging the air staying in the space surrounded by the mold material to the outside. In this case, there is a method of using a washer disposed between a nut and a base plate that are screwed onto an upper portion of each anchor bolt. This washer has a structure formed on the upper surface side of the washer so that a hole serving both for injecting the grout material and discharging the air communicates with the insertion hole of the anchor bolt (see Patent Documents 1 and 2). In addition, a method has been proposed in which the grout material is injected through an injection hole provided in the base plate or the mold material, and for discharging air during filling, a groove formed on the lower surface side of the washer or an opening formed in the side surface is used. (See Patent Documents 3 and 4).

Japanese Patent Laying-Open No. 2005-163299 (see FIG. 3) Japanese Patent Laying-Open No. 2005-61104 (see FIGS. 2 and 4) JP 2002-364070 A (see FIGS. 4 and 5) JP 2004-346509 A (see FIGS. 1 and 2)

  By the way, in these conventional filling methods, when the grout material starts to overflow from the injection hole provided in the washer (also used as the air discharge hole) or the air discharge groove provided separately from the injection hole, the subsequent grout material The injection pressure of the liquid drops rapidly, and it may be difficult to fill all the above-mentioned spaces without gaps. If this situation is reached and the base plate and foundation concrete are not sufficiently integrated, or if the axial force acts on the column base due to an earthquake, etc., and the friction resistance does not work, anchor bolts are the main Will be responsible for the shear force. As shown in FIG. 7, particularly in the bolt hole 14 a of the base plate 14, when the periphery of the anchor bolt 10 is not filled with the grout material G without a gap, the shear surface of the anchor bolt 10 corresponding to the lower surface of the base plate 14 is Both are threaded portions, and are in line contact or point contact with the wall surface of the insertion hole 21 of the washer 20 or the wall surface of the bolt hole 14a of the base plate 14 whose outer peripheral surface is integrated with the base plate 14 at the welded portion W. become. Such a contact state gives a concentrated load P to the trough 10a of the threaded portion which is the shearing surface of the anchor bolt 10.

  In such a situation, the shear force that the anchor bolt receives becomes a concentrated load in a linear state or a point state along the axial direction of the anchor bolt. This concentrated load induces stress concentration on the anchor bolt, and an early brittle fracture of the anchor bolt is assumed. That is, generally, the screw portion (triangular screw) of the bolt is an assembly of notches, and the stress changes in the portion where the shape changes in this way, and becomes larger than the average stress in the vicinity.

  Further, when this state is considered in units of column bases, the positional relationship between the shaft centers of the plurality of anchor bolts and the bolt holes 14a of the base plate is uniform at each location due to construction errors as shown in FIG. It is assumed that everything is different. When the shearing force P acts on the column base in such a state, it is expected that the anchor bolt 10A first shears and the remaining anchor bolts are destroyed in the order of 10B, 10C, and 10D. Since it is a premise that the shear force load of the anchor bolt acts equally on all the anchor bolts in the same cross section of the column base, the situation in which each of the anchor bolts 10A to 10D is destructively destroyed is This is a matter that must be avoided to ensure the earthquake resistance of buildings.

  The present invention has been made in view of the technical situation as described above, and by using the washer for an exposed type column base capable of improving the seismic performance of the column base by improving the filling property of the grout material. The purpose is to provide a fixing structure for the column base.

  In order to solve the above-mentioned problem, in the invention according to claim 1 of the present application, a steel column is provided with a nut screwed into an upper portion of an anchor bolt having a lower portion embedded in the basic concrete, and a bolt hole of the anchor bolt in a peripheral portion. The anchor bolt is disposed between the base plate fixed to the lower end of the base plate and the anchor bolt is inserted into the insertion hole, and the base plate is fixed to the base concrete by tightening the nut. A gap formed between the bottom surface and a gap formed between the inner peripheral surface of the bolt hole of the base plate and the outer peripheral surface of the anchor bolt is filled with a grout material made of non-shrink mortar, and the steel column is used as the foundation. A washer used for an exposed-type column base fixed on concrete, wherein the grout material is fastened at least 2 Air discharge groove of, radially outward from the insertion hole of the anchor bolt, wherein is provided a length of exposed beyond the outer periphery of the nut, is characterized in that where the configuration of.

  Furthermore, in the present invention, in the configuration of claim 1, the three air discharge grooves are provided radially (claim 2), and the width of the air discharge groove is 2 to 3 mm (claim 3). The exposed length of the air discharge groove is within 10 mm (Claim 4), which is a preferable condition for filling the grout material without any gaps. In addition, a fixing structure for the exposed column base can be obtained by using these washers.

  By adopting the above-described configuration, the present invention improves the filling property of the grout material, fills the gap between the lower surface of the base plate and the upper surface of the foundation concrete and increases their adhesion fixing force, and also provides bolt holes and washers for the base plate. By securely filling the gap around the anchor bolt in the insertion hole and protecting the threaded portion of the anchor bolt with a grout material, the shearing force acting on the exposed column base is smoothly transmitted to the foundation concrete via the anchor bolt. Become so. As a result, the fixing performance of the column base intended by the building designer is ensured, breakage due to stress concentration at the threaded portion of the anchor bolt is effectively suppressed, and the building can be prevented from collapsing.

(A)-(c) is the top view, front view, and sectional view on the AA line in (a) of the exposed type column base washer which concerns on this invention, respectively. (A) is a top view which shows the attachment state of the washer of FIG. 1, (b) is sectional drawing which shows the filling condition of grout material by an exposed type | mold column base. It is a top view which shows the state which applied the washer of FIG. 1 to the anchor bolt of an exposed type column base. It is a front view which shows the state before filling grout material with an exposed type | mold column base. (A) And (b) is sectional drawing and a top view which show the filling method of grout material with an exposed type column base, respectively. (A) And (b) is sectional drawing and a top view which show the other Example of the filling method of a grout material with an exposed type column base, respectively. (A) And (b) is sectional drawing which shows the contact condition of the anchor bolt with respect to the bolt hole of a baseplate, and the description which showed the state which an anchor bolt receives shear force in the prior art in the case of transmitting shear force to an anchor bolt, respectively. FIG. It is explanatory drawing which showed the relationship of the dispersion | variation in the position of the anchor bolt with respect to the bolt hole of a baseplate, and shear force.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an exposed type column washer according to the present invention, in which (a) is a plan view, (b) is a front view, and (c) is a cross-sectional view taken along the line AA in (a). The illustrated exposed column washer 1 has an anchor bolt insertion hole 3 formed substantially at the center of a washer body 2 having a substantially trapezoidal shape on the front and back surfaces, and penetrates in the thickness direction of the washer body 2. Three cut groove-like air discharge grooves 4 a, 4 b, 4 c have a shape provided radially (at intervals of 120 °) around the insertion hole 3. These air discharge grooves 4a, 4b, and 4c are used to fix the grout material to the inside of the washer main body 2 without leaking from the opening portion to the outside in the fixing structure of the exposed type column base described later. The length is set such that the tip end portion of the nut is exposed beyond the outer peripheral edge of the nut in a state where the nut is screwed into the bolt. The inner diameter of the anchor bolt insertion hole 3 is formed to be about 5 to 10 mm larger than the outer diameter of the anchor bolt used.

  FIG. 2A is a plan view showing an attached state of the exposed column base washer 1. The exposed type column base washer 1 is an upper end portion of an anchor bolt 10 protruding from a bolt hole formed as an oversized hole (generally, an anchor bolt diameter plus about 10 to 20 mm) in a peripheral portion of a base plate (not shown). Between the base plate and the tightening nut 11 screwed onto the base plate. In this embodiment, a general round washer 12 having an outer diameter slightly larger than the diagonal distance of the nut 11 is inserted between the nut 11 and the exposed column base washer 1. However, the round washer 12 is provided. Not necessary. As is apparent from the figure, the air discharge grooves 4a, 4b, 4c are exposed to the outside beyond the outer peripheral edge of the nut 11 and the round washer 12, respectively.

  FIG. 2B is a cross-sectional view showing a state of filling grout material in the fixing structure of the exposed column base according to the present invention. The anchor bolt 10 protruding from the upper surface of the foundation concrete 13 is inserted through the bolt hole 14a of the base plate 14 fixed to the lower end of the steel column (not shown), and the exposed column base washer 1 and the round washer 12 are inserted. In the state, it is tightened with two nuts 11. The gap between the upper surface of the foundation concrete 13 and the lower surface of the base plate 14, the gap between the bolt hole 14 a of the base plate 14 and the anchor bolt 10, and the gap between the insertion hole 3 of the exposed column base washer 1 and the anchor bolt 10, respectively. The material G is in a state of being integrally filled with no gap. In this case, the grout material G is transmitted through the anchor bolt 10 from the lower surface of the base plate 14 by a filling method to be described later, passes through the bolt hole 14a, and further pushes up, so that the insertion hole 3 of the exposed column base washer 1 is pushed up. The inside is filled without any gaps. As the grout material G used in the present invention, a non-shrink mortar that satisfies the three conditions of non-shrinkage, high fluidity and high strength is suitable, and the threaded portion (triangular screw) of the anchor bolt 10 due to its high fluidity. The valley portion 10a (valley bottom) can be reliably filled.

  As a blending example of the grout material G (non-shrink mortar), the weight ratio of non-shrinkage cement and aggregate (silica sand) is 50%, the water cement ratio is 30% or less, and the size of the aggregate (silica sand) is 2 to 3 mm. It is as follows. It is possible to fill the non-shrink mortar with such a composition into a narrow space (3 mm or more) if there is an appropriate injection pressure and air discharge hole. However, in a gap of 2 to 3 mm or less, the aggregate size of the non-shrink mortar becomes narrower, so that the aggregate stops at the entrance and only cement milk flows out. After a while, aggregate accumulates in the place and becomes a weir state, and the outflow of cement milk stops completely. Due to the characteristics of the non-shrink mortar, cement milk can be injected also into the air discharge grooves 4a, 4b, 4c of the exposed column base washer 1, so that the insertion hole 3 and the anchor of the exposed column base washer 1 are fixed. It can be confirmed that the grout material G (non-shrink mortar) is filled in the gap between the bolts 10. In the present invention, in particular, the anchoring mortar condenses in a solid filling state around the anchor bolt 10 which is a solid and constrained space, and thereby a constraining effect (confined effect) is exhibited and is usually obtained. The strength is several times the compressive strength, and other gaps are filled with non-shrink mortar so that the column bases are integrated and the seismic performance can be enhanced.

  As described above, the adhesion fixing force between the lower surface of the base plate 14 and the foundation concrete 13 is increased by the grout material G, and the periphery of the threaded portion of the anchor bolt 10, particularly including the valley portion 10 a, is protected by the grout material G. The shearing force acting on the column base is smoothly transmitted to the foundation concrete 13 through the anchor bolt 10 to secure the fixing performance of the column base intended by the building designer. It is possible to effectively suppress breakage of the anchor bolt 10 due to stress concentration on 10a and prevent the building from collapsing.

  Since the place where the grout material G is filled is a closed space surrounded by the mold material as will be described later, it is necessary to discharge the air staying on the lower surface side of the base plate 14 during the filling. If the air is insufficiently discharged, the location becomes a poorly filled location of the grout material G. Therefore, air venting means having an appropriate opening area is necessary, and in the exposed type column base washer 1 of the present invention, the three air discharge grooves 4 a, which are arranged in communication with the insertion hole 3 of the anchor bolt 10, 4b and 4c are provided. The intention is that, depending on the situation in which the anchor bolt 10 is in contact with the insertion hole 3 of the exposed column base washer 1, one of the air discharge grooves 4 a, 4 b, 4 c is blocked by the outer peripheral surface of the anchor bolt 10. This is because it is assumed that the situation cannot be fulfilled. Even in such a case, the remaining two air discharge grooves can play the role. Note that at least two air discharge grooves may be provided, and in this case, the facing position is desirable.

  The air discharge groove in the exposed-type column base washer of the present invention is intended to discharge air at the time of filling, and a grout material (non-shrink mortar, etc.) is held inside the exposed-type column base washer so that there is no leakage. However, it is included in this condition because there is not much difference in the effect to the extent that only a small amount of cement milk leaks. Specifically, the width of the air discharge groove is preferably 2 to 3 mm, and the exposed length of the air discharge groove is preferably 10 mm or less from the outer periphery of the nut. If it exceeds this range, the grout material leaks from the air discharge groove, and the injection pressure thereafter is greatly reduced, so that it becomes difficult to fill the necessary portions without any gaps.

  FIG. 3 is a plan view showing a state in which the exposed column base washer 1 is applied to the anchor bolt 10 of the exposed column base. The anchor bolts 10 are inserted into the bolt holes at the four corners of the rectangular base plate 14 fixed to the lower end of the steel column 15, the exposed column base washer 1 is inserted, and the nut 11 is tightened from above. The filling state of the grout material G on the lower surface side of the base plate 14 is as described above with reference to FIG. The exposed type column base washer 1 has a wide surface and a cross-sectional area around the insertion hole 3 of the anchor bolt 10, and when the outer periphery thereof is welded to the base plate 14 as in the prior art of FIG. This can contribute by reducing the amount of bending deformation of the base plate 14 and reducing the bending stress of the base plate 14.

  Next, a grout filling method for the exposed column base fixing structure according to the present invention will be described. FIG. 4 shows a state before the steel column 15 has been installed and before the grout material is filled. The exposed column base washer 1 of the present invention is sandwiched between the base plate 14 and the nut 11. Is provided. The steel column 15 to which the base plate 14 is fixed is supported by a level mortar 16 provided on the upper surface of the foundation concrete 13 and is in a state of being fastened by the anchor bolt 10 and the nut 11. The height of the level mortar 16 is about 20 to 50 mm, the size is about 2/3 of the dimension of the steel column 15 to which the base plate 14 is attached, and the height of the anchor bolt 10 filled with the grout material is 10 mm or more. Make sure the gap is secured.

  FIGS. 5A and 5B are a cross-sectional view and a plan view, respectively, showing a grout material filling method using exposed column bases. After the installation of the steel column 15 is completed, the mold material 17 is attached in close contact with the outer peripheral surface of the base plate 14. In addition, sealing is performed so that the grout material G such as non-shrink mortar to be filled does not flow out from the upper part or the lower part of the mold member 17. An injection hole 14b for the grout material G is formed in the base plate 14 in advance. Then, the grout filling funnel 18 is inserted into the injection hole 14b, and the grout material G is poured slowly. The grout material G fills the gap between the lower surface of the base plate 14 and the foundation concrete 13, further rises the bolt hole 14 a of the base plate 14, reaches the insertion hole 3 of the exposed column base washer 1, and the anchor bolt 10 The surrounding gaps can be filled with certainty. FIG. 6 is an embodiment showing a filling method different from FIG. In this embodiment, an injection hole is formed in the mold material 17, and the grout material G is filled from the side surface of the mold material 17 with the grout filling funnel 18.

  It is important to use a grout material G such as non-shrink mortar having excellent fluidity. In order to completely fill the entire area of the lower surface of the base plate 14 and directly below the nut 11, an appropriate flow rate of the grout material G and an appropriate injection pressure are required. As a method satisfying this, as shown in FIGS. 5 and 6, a grout filling funnel 18 having a certain height and an injection hole of about 20 mm is used. In the operation of injecting the grout material G, the grout material G is filled up to the top of the grout filling funnel 18. The height H that fills the grout material G is up to the height of the top of the anchor bolt 10. Under such conditions, the mass of the grout material G in the grout filling funnel 18 becomes an appropriate injection pressure, and continuous filling becomes possible, and all the gaps can be filled with the grout material G.

  In this way, a grout material consisting of non-shrink mortar with non-shrinkage, high strength and high fluidity ensures filling from the bottom surface of the base plate to the gap between the anchor bolt and the bolt hole of the base plate and the exposed column base washer. All the screw parts that appear downward from the nuts of the anchor bolts are covered with non-shrink mortar, so that the stress concentration generated in the screw parts is suppressed, and equal shear force is applied to each anchor bolt in the column base unit. Improve the seismic performance of buildings by making it bear. Further, by making the washer insertion hole and the base plate bolt hole slightly wider than the outer diameter of the anchor bolt, the filling property of the grout material such as non-shrink mortar is improved, and further, it leads to rationalization of the steel work.

  In addition, this invention is not limited to the said embodiment, For example, various change implementation is possible within the technical idea of this invention, such as a change of the number of air discharge grooves.

  The exposed washer for the column base according to the present invention exerts its superiority when used in a steel column base, and is further developed as a means to improve the seismic performance, workability and economy of the structural frame. Be expected.

  DESCRIPTION OF SYMBOLS 1 ... Exposed type column-base washer, 2 ... Washer main body, 3 ... Insertion hole, 4a, 4b, 4c ... Air exhaust groove, 10 ... Anchor bolt, 10a ... Valley part, 11 ... Nut, 12 ... Round washer, 13 ... Basic concrete, 14 ... base plate, 14a ... bolt hole, 15 ... steel column, 16 ... level mortar, 17 ... formwork, 18 ... funnel for grout filling, 20 ... washer, 21 ... insertion hole

In order to solve the above-mentioned problem, in the invention according to claim 1 of the present application, a steel column is provided with a nut screwed into an upper portion of an anchor bolt having a lower portion embedded in the basic concrete, and a bolt hole of the anchor bolt in a peripheral portion. The anchor bolt is disposed between the base plate fixed to the lower end of the base plate and the anchor bolt is inserted into the insertion hole, and the base plate is fixed to the base concrete by tightening the nut. A gap formed between the bottom surface and a gap formed between the inner peripheral surface of the bolt hole of the base plate and the outer peripheral surface of the anchor bolt is filled with a grout material made of non-shrink mortar, and the steel column is used as the foundation. a washer for use in exposed type column base for fixing onto concrete leakage on the outside of the grout from the opening portion At least two air discharge groove has a width to remain inside without being found radially outward from the insertion hole of the anchor bolt, it is provided by the length of exposed beyond the outer periphery of the nut The feature is that the configuration is adopted.

As a blending example of the grout material G (non-shrink mortar), the weight ratio of non-shrinkage cement and aggregate (silica sand) is 50%, the water cement ratio is 30% or less, and the size of the aggregate (silica sand) is 2 to 3 mm. It is as follows. It is possible to fill the non-shrink mortar with such a composition into a narrow space (3 mm or more) if there is an appropriate injection pressure and air discharge hole. However, in the gap of 2 to 3 mm or less, the aggregate size becomes narrower than the aggregate size of the non-shrink mortar, so that the aggregate stops at the entrance (the inner surface side of the air discharge hole) and only cement milk flows out. After a while, aggregate accumulates in the place and becomes a weir state, and the outflow of cement milk stops completely. The characteristics of such a non-shrink mortar, the air discharge groove 4a of the exposed type column base washer 1, 4b, stops aggregate on the lower surface side of 4c, the air discharge groove 4a, 4b, the cement milk to the inside of 4c Since it can be injected, it can be confirmed that the grout material G (non-shrinking mortar) is filled in the gap between the insertion hole 3 of the exposed washer 1 for the column base and the anchor bolt 10. In the present invention, in particular, the anchoring mortar condenses in a solid filling state around the anchor bolt 10 which is a solid and constrained space, and thereby a constraining effect (confined effect) is exhibited and is usually obtained. The strength is several times the compressive strength, and other gaps are filled with non-shrink mortar so that the column bases are integrated and the seismic performance can be enhanced.

Claims (5)

  An insertion hole for the anchor bolt between a nut screwed into the upper part of the anchor bolt with the lower part embedded in the foundation concrete and a base plate which is provided with a bolt hole of the anchor bolt at the periphery and is fixed to the lower end of the steel column In a state where the base plate is fixed on the foundation concrete by tightening the nut, a gap formed between the upper surface of the foundation concrete and the lower surface of the base plate, and an inner periphery of the bolt hole of the base plate A washer for use in an exposed column base for fixing a steel column on the foundation concrete by filling a grout material made of non-shrink mortar into a gap formed between a surface and an outer peripheral surface of the anchor bolt, At least two air discharge grooves for holding the grout material inside are radially extending from the anchor bolt insertion holes. Toward towards the exposed type column base washer, characterized in that provided in the length of exposed beyond the outer periphery of the nut.   The exposed type column base washer according to claim 1, wherein three air discharge grooves are provided radially.   The exposed washer for a column base according to claim 1 or 2, wherein the width of the air discharge groove is 2 to 3 mm.   The exposed washer for an exposed column base according to any one of claims 1 to 3, wherein the exposed length of the air discharge groove is within 10 mm.   An insertion hole for the anchor bolt between a nut screwed into the upper part of the anchor bolt with the lower part embedded in the foundation concrete and a base plate which is provided with a bolt hole of the anchor bolt at the periphery and is fixed to the lower end of the steel column In a state where the washer is disposed in a state where the base plate is inserted and the base plate is fixed onto the foundation concrete by tightening the nut, a gap formed between the upper surface of the foundation concrete and the lower surface of the base plate, a bolt hole of the base plate, and An exposed type column in which a gap formed between each inner peripheral surface of the insertion hole of the washer and an outer peripheral surface of the anchor bolt is filled with a grout material made of non-shrink mortar to fix the steel column on the foundation concrete. A leg fixing structure, wherein the washer is the washer according to any one of claims 1 to 4. The fixing structure of the exposed type column base.

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