JP2019190103A - Joint structure of building - Google Patents

Abstract

To provide a joint structure that can be manufactured on-site, can be miniaturized, and can be rationalized.SOLUTION: This connection structure joins an upper structure and a pile 10, and includes one or more fixing members provided on a pile head 10a of the pile so as to extend from the pile toward the upper structure, a cap member 11 which is provided so as to embed a pile head of the pile and the one or more fixing members and couples to the upper structure, a plate member having a hole through which the pile can be inserted, provided so as to cover a lower surface of an edge space portion of the cap member extending in the horizontal direction from an outer peripheral surface of the pile, and one or more rod-shaped members provided so as to be embedded in the cap member from the upper surface of the plate member adjacent to the lower surface of the edge space portion toward the upper structure.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a joint structure for joining a superstructure of a building and a pile.

  In joining the superstructure of a building and a pile, as shown in FIG. 1, the pile head 10 a which is the top of the pile 10 is connected to a foundation beam 12 and a column 13 as the superstructure through an area called a pile cap 11. Integrated.

  In order to transmit the bending moment generated in the pile head 10a, the fixing bar 14 is welded to the pile head 10a, and is embedded in the pile cap 11 from the viewpoint of securing the covering thickness of the reinforcing bar including the fixing bar 14. The covering thickness of the reinforcing bar is the thickness of the concrete covering the reinforcing bar. For this reason, the pile cap 11 is called the edge empty part 15 and protrudes from the side of the pile 10 in the horizontal direction. The structure bears moment and shear force.

  The marginal space 15 is conventionally designed to be thicker than 0.75D when the pile diameter of the pile 10 is D in order to ensure a predetermined strength against the bending and shearing forces. However, in this case, there is a problem that the size of the pile cap 11 becomes large and the construction becomes inefficient.

  In view of this, a technique has been proposed in which prestressing is introduced into the edge empty portion 15 to make the edge empty portion 15 thinner and to reduce the size, thereby making up for the strength reduction caused by making the edge empty portion 15 thinner (for example, Patent Documents). 1).

JP 2017-82548 A

  However, in the above technique, since the pile cap 11 is precast by factory production, the dimensions are strictly determined in advance, and allowance for variations in pile cores and pile head levels due to errors in pile construction at the site is allowed. There was a problem of becoming smaller.

  Then, it aims at providing the joining structure which can be manufactured on-site, can be reduced in size, and can aim at rationalization of construction.

The present invention has been made in view of the above problems, and is a joint structure that joins an upper structure of a building and a pile,
A cap member provided to embed a pile head of the pile and joined to the superstructure;
A plate member having a hole through which the pile can be inserted, provided so as to cover the lower surface of the edge space portion of the cap member extending in the horizontal direction from the outer peripheral surface of the pile;
There is provided a joining structure including one or more rod-like members provided so as to be embedded in the cap member from the upper surface of the plate member adjacent to the lower surface of the edge gap portion toward the upper structure.

  ADVANTAGE OF THE INVENTION According to this invention, the joining structure which can be manufactured on-site, can be reduced in size, and rationalization of construction can be provided.

The figure which illustrated the pile cap which joins the conventional superstructure and a foundation pile. The figure which showed an example of the conventional junction structure. The figure which simulated the behavior of the edge empty part of a pile cap. The figure which showed an example of the junction structure of this embodiment. Sectional drawing cut | disconnected by cutting line AA of FIG.

  Prior to describing the joint structure for joining the upper structure of the building and the pile of the present embodiment, a conventional joint structure will be described. FIG. 2 is a view showing an example of a conventional joining structure. The pile 10 is a foundation constructed by being driven into the ground in order to support a building. The pile 10 is, for example, a cylindrical ready-made concrete pile, and is installed by being embedded in a hole excavated by a machine. Ready-made concrete piles are piles that are manufactured at the factory, brought to the site and installed. The pile 10 is not limited to a ready-made concrete pile, and may be a steel pile.

  The foundation beam 12 that is a part of the superstructure is a beam that horizontally connects a column and the base of the column, and is constructed in the ground. After performing the operation of digging up the ground to create a predetermined space, the crushed stone 16 is spread and rolled with a plate or the like. Then, the bottom surface of the foundation, called abandoned concrete 17, is flattened and concrete for locating the building is placed. The foundation beam 12 is constructed by placing concrete on a flat surface of the discarded concrete 17. The foundation beam 12 is not limited to a reinforced concrete beam manufactured at a factory and brought into the field, or may be a steel beam such as I-shaped steel.

  The pile head 10a is provided with one or more fixing muscles 14 as fixing members so as to extend from the pile 10 toward the upper structure above the pile 10. The fixing muscle 14 is an anchor used for fixing the pile 10 to the pile cap 11 as a cap member. Incidentally, the bonding strength between the superstructure and the pile 10 is basically based on the anchoring muscle 14. The fixing bar 14 is a reinforcing bar having a predetermined length and is attached to the outer peripheral surface of the pile head 10a by welding or the like.

  If the pile diameter of the pile 10 is small, the number of the fixing bars 14 that can be attached to the outer peripheral surface is limited, and the necessary number may not be provided in view of the bonding strength. As a countermeasure, the pile cap 11 can be constructed such that a predetermined length of the pile head 10a is employed as a fixing portion and the pile head 10a is embedded together with the fixing muscle 14.

  In order to construct the pile cap 11 so as to embed the pile head 10a, the ground around the pile head 10a is dug one level deeper than the ground of the foundation beam 12, and crushed stone 18 is laid on that portion, and the discarded concrete 19 is cast. . This operation can be performed simultaneously with the operation of laying the crushed stone 16 of the foundation beam 12 and placing the discarded concrete 17. The pile cap 11 is constructed such that a formwork is provided on a flat surface of the discarded concrete 19 and the concrete is placed, and the pile 10 and the foundation beam 12 are joined.

  As a result, an empty edge portion 15 of the pile cap 11 extending in the horizontal direction parallel to the flat surface of the discarded concrete 19 is formed from the outer peripheral surface of the pile 10, and the bending moment and shear force generated by the horizontal force at the time of the earthquake are The empty part 15 has to bear.

  In order to ensure its strength, it is not particularly defined by standards, etc., but as a rule, the thickness W of the marginal space 15 should be thicker than 0.75D when the pile diameter of the pile 10 is D. ing.

  Here, how the behavior of the pile cap 11 changes when a horizontal force is applied to the pile 10 by changing the thickness of the edge space 15 of the pile cap 11 will be described.

  FIG. 3 (a) shows a simulation result by a three-dimensional finite element method analysis when 0.75D is used as a conventional practice, and FIG. 3 (b) shows a simulation result when the thickness is made thinner than 0.75D and 0.5D. FIG. The finite element method is a method of dividing an upper structure and a pile cap into a plurality of elements, deriving an approximate expression representing displacement for each divided element, and obtaining an approximate solution of the entire structure from the derived approximate expression. The horizontal force is applied from the left side toward the right side as indicated by the arrow. The simulation results show the displacement (mm) in the x-axis direction and the z-axis direction, but the color difference shown as contour lines (contours) represents only the displacement in the z-axis direction.

  When a horizontal force is applied to the pile 10 in the direction indicated by the arrow, the portion to which the horizontal force is applied tends to bend greatly, but a force that resists the pile head 10a acts on the pile head 10a. Pushes the pile cap 11 in the direction opposite to the direction of the applied force.

  When the thickness of the marginal space 15 is 0.75D, the pile head 10a pushes the pile cap 11 as shown in FIG. 3 (a). However, it is predicted from the simulation result that the shape of the pile cap 11 is maintained.

  On the other hand, when the thickness of the edge blank portion 15 is 0.5D, as shown in FIG. 3 (b), the thickness is not sufficient, so the displacement of the portion adjacent to the pile head 10a is large. The lower surface of the empty space 15 is greatly displaced, and it is predicted from the simulation results that the lower surface of the empty space 15 rises. This is presumed to be because the lower surface of the marginal space 15 of the pile cap 11 is only in contact with the discarded concrete 19 and is easily displaced.

  In this way, when a horizontal force is applied due to the shaking of the earthquake, it is predicted that the lower surface of the marginal space portion 15 will rise, so if this portion can be reinforced so as not to rise, Can be thinner than 0.75D.

  Therefore, the joining structure can be a structure as shown in FIG. FIG. 4 is a view showing an example of the bonding structure of the present embodiment. In this joining structure, the foundation beam 12 is constructed after the crushed stones 16 are laid and the discarded concrete 17 is cast in the same manner as the conventional joining structure shown in FIG. In addition, the pile cap 11 is constructed after the fixing bars 14 are attached to the pile head 10a, the crushed stones 18 are laid down, and the discarded concrete 19 is placed. The fixing muscle 14 can be provided as necessary.

  In the joint structure shown in FIG. 4, the ground surface is dug down so that the thickness W of the marginal space portion 15 is less than 0.75D, the crushed stone 18 is spread, the discarded concrete 19 is cast, and then the flat surface of the discarded concrete 19 A reinforcing steel plate 20 as a plate member is disposed on the top. Since the plate member is provided to reinforce the lower surface of the margin empty portion 15, the plate member is made of a material having higher strength than the concrete constituting the margin empty portion 15. The reinforcing steel plate 20 is provided with, for example, one or more screw grooves, and one or more bar members having a thread are screwed into each screw groove. The anchor bars 21 may be fixed to the reinforcing steel plate 20 by welding or the like.

  After placing the reinforcing steel plate 20 to which the anchor bars 21 are attached on the abandoned concrete 19, the concrete is placed and the pile head 10 a, the anchor bars 14, and the anchor bars 21 are embedded and joined to the foundation beam 12. The pile cap 11 is constructed.

  The thickness W of the marginal space 15 is not less than the thickness that can secure the covering thickness of the anchor muscle 21 and may be any thickness as long as it is thinner than 0.75D. Cover thickness is the thickness of the concrete covering the reinforcing bar, preventing corrosion of the reinforcing bar by water, air, acid, base, effectively attaching the reinforcing bar and concrete, and having the prescribed durability and strength, It is defined by the part of the building.

  By the way, since the upper part and the peripheral part of the anchor bar 21 are embedded in the pile cap 11, the covering thickness can be ensured. However, since the lower part of the anchor bar 21 is attached to the reinforcing steel plate 20, the covering thickness is increased. I can't secure it.

  Therefore, the discarded concrete 19 adjacent to the lower surface of the reinforcing steel plate 20 is cast to a predetermined thickness using concrete equivalent to the pile cap 11, and the discarded concrete 19 is included in the covering thickness of the anchor bar 21. Can do.

  FIG. 5 is a cross-sectional view taken along the cutting line AA shown in FIG. The pile 10 is a hollow circular pipe, and concrete is cast therein, and one or more fixing bars 14 are attached to the outer peripheral surface thereof by welding or the like. In the example shown in FIG. 5, eight fixing bars 14 are attached every 45 ° along the outer peripheral surface of the pile 10. As long as a predetermined bonding strength can be ensured, the number of fixing muscles 14 may be any number, and the length and diameter may be any length and diameter.

  The reinforcing steel plate 20 has a hole through which the pile 10 can be inserted at the center thereof, and covers the edge space 15 of the pile cap 11. The shape of the reinforcing steel plate 20 is not limited to a rectangle as long as it can cover the marginal space 15.

  The anchor bars 21 are attached to the reinforcing steel plate 20, and in the example shown in FIG. 5, eight anchor bars 21 are attached to the outer periphery side of the fixing bars 14 every 45 °. The number of anchor bars 21 may be any number as long as an upward force that resists the force of the reinforcing steel plate 20 moving downward due to the upward deformation can be applied and the deformation can be suppressed. The sheath diameter may be any length or diameter.

  Further, the anchor bars 21 may be embedded in the pile cap 11 in a state in which not only the lower part connected to the reinforcing steel plate 20 but also the upper part is provided with a screw thread and a nut or the like is screwed. As a result, it is possible to counter the rising deformation with a smaller number, and to reduce the thickness W of the edge empty portion 15.

  Although the dimension of the outer periphery of the rectangle of the reinforcing steel plate 20 can be the same as the dimension of the outer periphery of the cross section of the pile cap 11, that is, the outer periphery of the edge empty part 15, the entire lower surface of the edge empty part 15 can be covered. As shown in FIG. 5, it is preferable to make the size smaller than the outer circumference of the marginal space 15. This is because even if some construction error occurs in the pile core position of the pile 10, it can be used for the same member without protruding from the marginal space 15.

  As described above, in the foundation structure that bears the horizontal force by the thickness of the pile head 10a embedded in the pile cap 11 and the edge space 15 that covers the pile head 10a, the reinforcing steel plate 20 that covers the lower surface of the edge space 15 is disposed. The thickness of the marginal space 15 of the pile cap 11 can be made thinner than before. Thereby, the structure which reduced the plane dimension of the pile cap 11 can be designed. In addition, the structure and construction can be rationalized by reducing the planar dimensions of the pile cap 11.

  The joint structure of the present invention has been described in detail with reference to the embodiments shown in the drawings, but the present invention is not limited to the above-described embodiments, and other embodiments, additions, and modifications are made. It is possible to make modifications within the range that can be conceived by those skilled in the art, such as deletion, and any aspect is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

DESCRIPTION OF SYMBOLS 10 ... Pile 10a ... Pile head 11 ... Pile cap 12 ... Foundation beam 13 ... Column 14 ... Fixation bar 15 ... Marginal part 16 ... Crushed stone 17 ... Discarded concrete 18 ... Crushed stone 19 ... Discarded concrete 20 ... Reinforced steel plate 21 ... Anchor bar

Claims (5)

It is a joint structure that joins the superstructure of a building and a pile,
A cap member provided to embed a pile head of the pile, and joined to the superstructure;
A plate member having a hole through which the pile can be inserted, provided so as to cover a lower surface of a marginal portion of the cap member extending in a horizontal direction from an outer peripheral surface of the pile;
1 or more rod-shaped members provided so that it may embed in the said cap member toward the said upper structure from the upper surface of the said plate member adjacent to the lower surface of the said edge empty part.   The joint structure according to claim 1, wherein a dimension of the outer periphery of the upper surface of the plate member is smaller than a dimension of the outer periphery of the lower surface of the edge empty portion.   The joint structure according to claim 1 or 2, wherein a thickness of the marginal space is thinner than a thickness obtained by multiplying a pile diameter of the pile by 0.75.   The joining structure according to any one of claims 1 to 3, wherein the lower surface of the plate member is covered with discarded concrete placed on the lower surface of the plate member. Including one or more fixing members provided on a pile head of the pile so as to extend from the pile toward the superstructure,
The joining structure according to claim 1, wherein the cap member is provided so as to embed the one or more fixing members.