JP2010024658A - Joint structure of reinforced concrete member, and building using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of a reinforced concrete member, which can effectively reduce stress, caused by bending moment causing occurrence of crushing, only in a location of formation of a hinge or a location capable of remarkably causing the crushing of the concrete before the formation of the hinge, without being premised on the adoption of ultrahigh strength concrete, in consideration of the joint structure of the reinforced concrete member and a fixing end; and to provide a building using the joint structure of the reinforced concrete member. <P>SOLUTION: A reinforced concrete column member 1, in which a main reinforcement 7 for a column and a hoop reinforcement 8 are embedded and a pressure reducing reinforcement 10 for bearing axial stress is embedded in an area inside the hoop reinforcement and on the side of uneven distribution of great compression stress, is joined to the side of a footing beam 2 by anchoring an anchoring end 10a of the pressure reducing reinforcement on the side of the footing beam 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention takes into account the joint structure between a reinforced concrete (hereinafter referred to as RC) member and a fixed end, and does not assume the use of ultra-high-strength concrete. The present invention relates to a joint structure of RC members that can be effectively reduced by narrowing down to a portion where concrete collapse may occur significantly before occurrence of a hinge or a hinge, and a building using the same.

  The RC column member is a structural material that bears an axial force from above. For example, an RC column on the first floor of a building is usually joined to a fixed end such as a foundation beam or a footing including a floor slab on the first floor. When this RC column receives a high axial force from the upper floor and undergoes deformation due to a lateral seismic force, as shown in FIG. 10, the column base portion c of the RC column b joined to the fixed end a, as shown in FIG. A hinge due to a bending moment is generated at the lower end edge, and concrete crushing d occurs. When the crushing d occurs, the bending strength of the RC column b decreases rapidly. Moreover, the cross-sectional defect | deletion by crushing reduces the axial direction yield strength of RC pillar b.

  As can be understood from FIG. 11 showing the entire building, this type of phenomenon occurs when the high-rise part of the building e is displaced horizontally by the seismic force so as to protrude outward from the low-rise part. The lower floor where the axial force f increases due to the bending moment, particularly in the outer RC column g, appears prominently.

  This may occur in the same manner not only in the outer peripheral columns of the lower floors but also in the column bases of RC column members on each floor where the column beam joints are fixed ends. For RC column members, in addition to this, the axial force is reduced by seismic force, so-called tension side columns, or the outer peripheral columns of buildings that are designed to bear the seismic force on the core wall, etc. The same can be said. Furthermore, crushing can also occur between the column head of the RC column member on the top floor of the building and the roof slab to which it is joined.

  In addition to RC column members, there are RC pile members, wall pile members, and wall members as structural materials that bear the axial force from above. In a pile member or a wall pile member, a pile head as a material end is joined to a fixed end such as a foundation beam or a footing. In a wall member, an upper end part and a lower end part are joined to fixed ends, such as a beam and a floor slab. Even with structural materials other than these pillar members, when receiving a lateral seismic force while receiving an axial force from above, hinges due to bending moments occur at the end of the material, causing concrete collapse. obtain.

  In order to deal with this type of problem, “reinforced concrete column structure” in Patent Document 1 and “precast concrete member” in Patent Document 2 are known as techniques targeting only concrete columns.

  Patent Document 1 is formed of concrete with a different mix of cover concrete at the lower end of the column and concrete at other parts for the purpose of preventing crushing and peeling of the cover concrete during an earthquake and reducing material costs. The cover concrete at the lower end is formed of a precast cylinder made of ultra-high strength and high-toughness concrete, and the other parts of concrete are formed of ultra-high-strength concrete. It is what.

Patent Document 2 is intended to be used as a high-strength, high-toughness, high-durability precast concrete column that is excellent in earthquake resistance and durability, is economical, and can shorten the construction period. A hollow shell is formed with high-strength mortar, the hollow part of the shell is shaped according to the required seismic performance, the part where large stress is applied is thick, and the part where small stress is applied is thin. It is to make.
JP 2005-146601 A JP 2006-233548 A

  In these patent documents, the RC column member alone is used to prevent crushing or to take measures to improve toughness and durability, and considers even the fixed end to which the RC column member is joined. However, there is a problem that there is a limit to the structural performance to be obtained. Moreover, these patent documents are based on the premise that ultra-high strength concrete is adopted, and there is a problem that material costs increase.

  The present invention was devised in view of the above-mentioned conventional problems, taking into account the joint structure of the RC member and the fixed end, and without causing the use of ultra-high-strength concrete, RC member joint structure capable of effectively reducing stress caused by a certain bending moment to a location where a hinge occurs or a location where concrete collapse may occur significantly before the hinge is generated, and using the same The purpose is to provide buildings.

  The RC member joint structure according to the present invention is a decompression rebar that bears axial stress in a region where the main bar and the hoop bar are embedded and a large compressive stress is unevenly distributed inside the hoop bar. The reinforced concrete member embedded with is fixed to the fixed end of the decompression reinforcing bar and joined to the fixed end.

  The decompression reinforcing bar is not adhered to concrete at a material shaft end portion of the reinforced concrete member.

  The reinforced concrete member is provided with a joint reinforcing bar fixed at the fixed end at one end side in the arrangement of the main reinforcing bar and the lap joint, and the other end side is provided with the joint reinforcing bar at one end side. It is characterized in that it is not attached to concrete in a partial range around the shaft end.

  The said reinforced concrete member is a concrete pile member, Comprising: The outer diameter dimension of the upper part of the pile head part of this concrete pile member was formed by reducing in diameter rather than another part, It is characterized by the above-mentioned.

  The building according to the present invention is characterized in that the joint structure of the RC member is used for joining at least a part of the reinforced concrete members arranged on the outer periphery of the building and the fixed end.

  In the RC member joint structure and the building using the same according to the present invention, the joint structure between the RC member and the fixed end is taken into consideration, and the occurrence of crushing is made without assuming the use of ultra high strength concrete. The stress due to the bending moment, which is the cause, can be effectively reduced by narrowing down to the location where the hinge is generated or the location where the concrete collapse may occur significantly before the hinge is generated.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments of a RC member joining structure according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a first embodiment of a joint structure of RC members according to the present invention. In the first embodiment, the RC column member 1 on the first floor of the building that bears the load from the upper floor will be described as an example of the RC member that receives the axial force from above. FIG. 1A is a schematic front view around the RC column member 1 on the first floor, FIG. 1B is a schematic front sectional view showing the inside of the RC column member 1 and the surrounding arrangement, and FIG. It is a plane sectional view showing the bar arrangement inside the RC column member.

  In the vicinity of the column base 1a of the RC column member 1 on the first floor of the building, a footing 4 is provided on the pile member 3 at the intersection of the foundation beams 2 arranged vertically and horizontally. A floor slab 5 on the first floor of the building is laid on the foundation beam 2. The foundation beam 2, the pile member 3, the footing 4, and the floor slab 5 are constructed with an RC structure. The RC column member 1 rises from the foundation beam 2 and is provided on the floor slab 5. The column base 1a of the RC column member 1 may be joined using the foundation beam 2 including the floor slab 5 as a fixed end, or may be joined using the footing 4 as a fixed end. In this embodiment, the RC column member 1 is joined to a building foundation portion including other footings 4 and pile members 3 with the foundation beam 2 including the floor slab 5 as a fixed end.

  The RC column member 1 basically has a column main reinforcement 7 arranged in the column concrete 6 at intervals in the circumferential direction of the column, and surrounds the column main reinforcement 7 with an interval in the height direction of the columns. It is formed by burying hoop muscles 8 arranged in a row. A column rebar bar 9 comprising column main bars 7 and hoop bars 8 is projected downward from the lower end of the RC column member 1, and the column bar bar 9 reaches the footing 4 from the base beam 2 and is fixed to them. The column member 1 is joined to the building foundation.

  The material of the column concrete 6 of the RC column member 1 may be ordinary concrete, high strength / ultra high strength concrete, or a mixture of steel fiber, carbon fiber, resin fiber or the like as a reinforcing material. Also good. In addition, the RC column member 1 is constructed by hitting concrete on-site, whether it is a hollow shell precast concrete cylinder filled with filled concrete or solid precast concrete. Also good.

  In the present embodiment, in addition to the RC column member 1 formed in this manner, a decompression rebar 10 is embedded. The decompression rebar 10 is also fixed to the bottom end portion 10a of the reinforcing bar 10 by reaching the foundation beam 2 and the footing 4 from the floor slab 5. “For decompression” means to resist the compressive stress and tensile stress generated in the RC column member 1 in the axial direction, in particular compressive stress and bear this, compared to the case where the reinforcing bar 10 is not provided. It means that it functions so as to reduce the burden on the column main reinforcement 7 and the column concrete 6. As a material, it may be equivalent to a general rebar.

  In the RC column member 1, the decompression reinforcing bar 10 is arranged inside the hoop bar 8 so that a necessary concrete covering thickness is ensured and no complication with the column main bar 7 occurs. In addition, the decompression reinforcing bar 10 is arranged in a region on the side where a large compressive stress is unevenly distributed in the plane cross section of the RC column member 1. The region on the side where a large compressive stress is unevenly distributed in the plane cross section of the RC column member 1 can be estimated by stress analysis. For example, in the case of a building having a rectangular planar outline, for example, the side of the RC column member 1 located on the outer periphery of the RC column member 1 that faces the outside of the building is a region in which large compressive stress is unevenly distributed.

  The length of the decompression rebar 10 is the direction of the column axis generated inside the RC column member 1 in accordance with the stress distribution in the column height direction in addition to the fixing length of the lower end portion 10a fixed to the foundation beam 2 and the like. It is set to a column height range in which it is necessary to reduce the burden on the column main reinforcement 7 and the column concrete 6 by bearing the compressive stress and tensile stress.

  In the illustrated example, two reinforcing bars 10 for pressure reduction are arranged near the left side in the plane cross section of the RC column member 1. According to the result of stress analysis or the like, the number of reinforcing bars 10 for decompression is one or a plurality of bars to the extent that it is necessary to reduce the burden on the column main bars 7 and the column concrete 6. In the illustrated example, the two decompression reinforcing bars 10 are arranged in a straight line in a line, but may be arranged in two or more lines, or may be arranged in an arc. Further, a plurality of decompression reinforcing bars 10 may be bundled into one set, and a plurality of these sets may be arranged. The bar arrangement position of the decompression rebar 10, that is, the depth x from the column surface of the RC column member 1 may be appropriately set according to the result of stress analysis.

  The bar arrangement work of the decompression rebar 10 may be performed by positioning from the column main reinforcement 7 or the hoop reinforcement 8 with a binding wire. When the RC column member 1 is made of precast, the decompression rebar 10 may be embedded in advance in advance, or may be arranged at the time of placing concrete-filled concrete. In the case where the RC column member 1 is on-site placement, the reinforcement is performed in parallel with the reinforcement of the column main reinforcement 7 or the like, and then on-site concrete is placed.

  The decompression rebar 10 reaches the footing 4 from the foundation beam 2 together with the column reinforcement bar 9 and is fixed thereto, whereby the RC column member 1 is joined to the building foundation including the foundation beam 2 and the like.

  In the present embodiment, a joint rebar 11 is further embedded in the RC column member 1. As a material, it may be equivalent to a general rebar. The joint rebar 11 has at least the upper end side 11a embedded in the RC column member 1 in the arrangement of the column main reinforcement 7 and the overlap joint, and the lower end side 11b is footed from the foundation beam 2 including the floor slab 5 serving as a fixed end. 4 is fixed.

  In the present embodiment, the joint rebar 11 is arranged at the building foundation portion with the column main reinforcement 7 and the lap joint. Arrangement of lap joints means that they are overlapped to such an extent that stress can be transmitted between the column main bars 7 and the joint rebars 11. Both the case where they overlap completely like a lap joint and the case where they are separated a little like fixing. Including. For fixing, there are a case where a fixing hardware such as a nut is used and a case where it is bent into a hook shape.

  Further, the joint rebar 11 is not attached to the column concrete 6 at the upper end side 11a around the column base 1a above the floor slab 5 (hereinafter referred to as “attachment cutting portion P”). "). The adhesion cut portion P that does not adhere to the column concrete 6 may be formed by a known means. For example, if the grease is applied around the joint rebar 11 or is covered with a cloth or a sleeve, the adhesion action of the concrete is prevented. Good.

  The joint rebar 11 is basically a member on the side where the adhesion cut portion P is formed at the boundary between the column base 1a of the RC column member 1 which is the joint and the foundation beam 2 including the floor slab 5. In the embodiment, a part of compressive stress and tensile stress due to the bending moment generated in the RC column member 1 is borne. More specifically, in the joint rebar 11, the range of adhesion with the concrete excluding the adhesion cut portion P follows the deformation of the RC column member 1 and the like, while the adhesion cut portion P is within the range and the column height. By freely expanding and contracting in the direction and further yielding, both the compressive stress and tensile stress in the column axis direction at the boundary between the RC column member 1 and the foundation beam 2 and the like are effectively borne.

  Therefore, in the case where the joint rebar 11 is provided, in the joining of the RC column member 1 and the building foundation portion including the foundation beam 2, the column main reinforcement 7 exists from the RC column member 1 to the foundation beam 2 and the footing 4. Since the column main reinforcement 7 adheres to the surrounding concrete to the periphery, the column main reinforcement 7 integrated with the concrete exists at a position corresponding to the adhesion cut portion P of the column base 1a, and a hinge is generated. The column base 1a of the RC column member 1 can be given resistance.

  In the drawing, the joint reinforcing bars 11 are arranged with respect to all the column main reinforcing bars 7, but may be arranged with respect to a part of the column main reinforcing bars 7. The length of the joint rebar 11 may be appropriately set as long as the length exceeds the periphery of the column base 1 a of the RC column member 1 from the building foundation including the foundation beam 2. In the illustrated example, it is set so as to reach from the footing 7 above the column base 1a.

  In the present embodiment, the length relationship between the joint rebar 11 and the decompression rebar 10 is the same fixing length in the building foundation portion under the floor slab 5, and the joint rebar 11 within the RC column member 1. Is set to be longer than the decompression rebar 10. However, the length relationship between the joint rebar 11 and the decompression rebar 10 may be appropriately set according to the result of stress analysis. That is, the decompression rebar 10 has a function of bearing the stress in the column axis direction in the region where the large compressive stress is unevenly distributed inside the RC column member 1, and the joint rebar 11 has the resistance of the joint. Since it has an increasing function, the length relationship may be set according to the performance to be exhibited by each. The bar arrangement work of the joint rebar 11 may be performed in the same manner as the bar arrangement work of the decompression rebar 10.

  Next, the effect | action of the joining structure of RC member concerning 1st Embodiment is demonstrated. The work of joining the RC column member 1 to the building foundation part including the foundation beam 2 is simply adding the rebar 10 and the joint rebar 11 and constructing it by various well-known methods. can do.

  When the RC column member 1 receives an earthquake force from the lateral direction while bearing an axial force, a bending moment is generated at the column base 1a. Due to this bending moment, in the flat cross section of the column base portion 1a, one becomes the tension side and the other becomes the compression side, and a hinge is generated (see FIG. 10). That is, the RC column member 1 has a region in which a large compressive stress is unevenly distributed in the plane cross section.

  In the first embodiment, in this region of the RC column member 1, the lower end portion 10a is fixed to the foundation beam 2 including the floor slab 5, and the decompression rebar 10 that bears the axial stress is embedded. Therefore, the unevenly distributed compressive stress can be borne by the decompression rebar 10 which resists this, and the compressive stress received by the column main reinforcement 7 and the column concrete 6 by flowing the stress to the foundation beam 2 side which is a fixed end. Can be relaxed.

  Thus, the decompression rebar 10 fixed on the foundation beam 2 side can bear the compressive stress including the building foundation part including the foundation beam 2, so that the collapse at the column base 1 a is delayed. Or the occurrence of crushing can be prevented. Thereby, the bending strength of RC pillar member 1 can be maintained longer. Moreover, since crushing generation | occurrence | production can be prevented, a cross-sectional defect does not arise in RC pillar member 1, but the axial direction yield strength of RC pillar member 1 can also be maintained.

  In addition, since it has an adhesion cut portion P that prevents the adhesion to the concrete in the column axis direction and allows the reinforcement to expand and contract, and additionally provided the joint reinforcement 11 that bears both compressive stress and tensile stress, Under the situation where the rebar 10 for decompression is acting, it is possible to increase the resistance at the joint between the RC column member 1 and the foundation beam 2 including the floor slab 5 serving as a fixed end, thereby effectively reducing the stress burden. It is possible to more effectively prevent the RC column member 1 from being damaged due to the occurrence of a hinge around the joint between the RC column member 1 and the foundation beam 2 by moving to the decompression rebar 10.

  As described above, the RC member joint structure according to the first embodiment is described in the background art taking into account the joint structure of the foundation beam 2 including the RC column member 1 and the floor slab 5. Without assuming the use of such ultra-high-strength concrete, the stress due to the bending moment, which is the cause of crushing, is narrowed down to the location where the hinge occurs or where the concrete can be significantly collapsed before the hinge occurs. Can be effectively reduced.

  Moreover, when constructing the joint structure, it is only necessary to additionally arrange the decompression rebar 10 and the joint rebar 11 to the column rebar rod 9, and the RC column member 1 can be constructed at low cost and with good workability. Crushing can be prevented. Since the decompression rebar 10 is arranged inside the hoop 8, it is possible to prevent the RC column member 1 from being crushed while preventing the complication of the bar arrangement by preventing the complication with the column main reinforcement 7. .

  FIG. 2 shows a second embodiment of the RC member joining structure according to the present invention. The second embodiment is an example applied to a building that does not include the foundation beam 2. In the case of a building that does not include the foundation beam 2, the upper surface of the footing 4 may be considered as a fixed end.

  The difference from the first embodiment is that the fixed end is the upper surface of the footing 4, and therefore the adhesion cut portion P of the joint rebar 11 is set with the upper surface of the footing 4 as a boundary. In this case, it is preferable that the decompression rebar 10 is provided up to the exposed column base 1a on the soil slab (not shown). Even in the second embodiment, it is needless to say that the same effects as those of the first embodiment can be obtained only by changing the position in consideration of the fixed end.

  FIG. 3 shows a third embodiment, and FIG. 4 shows a fourth embodiment. In these embodiments, the joint rebar 11 of the first and second embodiments is omitted. Three reinforcing bars 10 for decompression are arranged, and the effects obtained by the reinforcing bars 10 for decompression are the same as in the above embodiment.

  Further, in particular, in FIG. 3, the decompression rebar 10 is adhered to concrete as a whole, as in the above embodiment, whereas in FIG. 4, the decompression rebar 10 is depicted in the first and second embodiments. The upper end 10b side is a partial range around the upper column base 1a, with the upper end 10b side being the boundary between the upper surface of the floor slab 5 or the upper surface of the footing 4 and the RC column member 1 in the same configuration as described in the above. Therefore, it is not attached to the column concrete 6 (hereinafter, the partial range is referred to as “unconstrained expansion / contraction portion Q”).

  In the unconstrained stretchable part Q, the compressive stress or the like borne by the decompression rebar 10 is not transmitted to the column concrete 6. By forming such an unconstrained expansion / contraction part Q, the decompression rebar 10 is not unconstrained while the range attached to the concrete excluding the unconstrained expansion / contraction part Q follows the deformation of the RC column member 1 and the like. The expansion / contraction part Q extends and contracts freely in the column height direction within that range, transmits stress without passing through the concrete, and further yields, for example, the unconstrained expansion and contraction of the concrete in the range where adhesion has been removed. Since the axial stress and the bending stress of the portion Q are alleviated, even if a hinge due to a bending moment occurs, both the compressive stress and the tensile stress in the column axial direction are more effectively borne and the column leg 1a is bent. Yield strength can be maintained. Since the decompression rebar 10 bears the compressive force more effectively after the tensile yield, the formation of the unconstrained expansion / contraction part Q is extremely effective.

  Although not shown, an unconstrained expansion / contraction portion Q may be provided in the decompression rebar 10 of the first and second embodiments.

  FIG. 5 shows a fifth embodiment of a joint structure of RC members according to the present invention. In the fifth embodiment, an RC pile member 3 that bears a load from above the footing 4 will be described as an example of an RC member that receives an axial force from above. FIG. 5A is a schematic front cross-sectional view showing the bar arrangement around the pile head 3a, and FIG. 5B is a plan cross-sectional view showing the bar arrangement inside the pile head 3a. The pile member 3 may be of any conventionally known structure type / construction type, such as a ready-made pile or a cast-in-place pile. In the illustrated example, the foundation beam 2 is not shown, but may be a building foundation portion provided with the foundation beam 2. An RC column member 1 is provided on a pile head 3 a of the pile member 3 via a footing 4.

  The pile member 3 is basically arranged inside the pile concrete 12 with pile main bars 13 arranged at intervals in the circumferential direction of the pile, and surrounding these pile main bars 13 with an interval in the height direction of the pile. It is formed by embedding a pile reinforcing bar 15 composed of hoop bars 14 that have been arranged. The footing 4 is joined on the pile head 3a of the pile member 3 formed in this way. The lower surface of the footing 4 is a fixed end of the pile member 3.

  In this embodiment, in addition to the pile member 3 formed in this manner, the decompression rebar 10 is embedded. The decompression rebar 10 is fixed to the footing 4 at the fixing end, which is the upper end 10 b. As in the case of the RC column member 1 of the first embodiment, the decompression rebar 10 is arranged inside the hoop bar 14 so that a necessary concrete covering thickness is ensured and no complication with the pile main bar 13 occurs. Be streaked. Further, the rebar 10 for decompression is arranged in a region where a large compressive stress is unevenly distributed in the plane cross section of the pile member 3.

  The length of the decompression reinforcing bar 10 is the compression in the pile axial direction generated in the pile member 3 in accordance with the stress distribution in the depth direction of the pile in addition to the fixing length of the upper end portion 10b fixed to the footing 4. It is set to a pile depth range where it is necessary to reduce the load on the pile main bars 13 and the pile concrete 12 by bearing stress and tensile stress.

  In the illustrated example, three reinforcing bars 10 for pressure reduction are arranged near the left side in the plane cross section of the pile member 3. The number of reinforcing bars 10 for decompression is set to one or more bars to the extent that it is necessary to reduce the load on the pile main bars 13 and the pile concrete 12 according to the result of stress analysis or the like. Further, in the illustrated example, the three decompression reinforcing bars 10 are arranged in a straight line in a line, but may be arranged in two or more lines, or may be arranged in an arc. Further, a plurality of decompression reinforcing bars 10 may be bundled into one set, and a plurality of these sets may be arranged. The bar arrangement position of the decompression rebar 10, that is, the depth y from the outer surface of the pile member 3 may be appropriately set according to the result of stress analysis.

  The bar arrangement work of the decompression reinforcing bar 10 may be performed by positioning from the pile main reinforcing bar 13 or the hoop bar 14 with a binding wire. When the pile member 3 is an off-the-shelf pile, the decompression rebar 10 may be embedded in advance in advance, or may be arranged at the time of placing in-filled concrete. When the pile member 3 is placed on-site, the placement is performed in parallel with the reinforcement such as the pile main reinforcement 13 and then the on-site cast concrete is placed. The decompression rebar 10 is fixed to the footing 4, whereby the pile member 3 is joined to the footing 4.

  Even in the present embodiment, the joint rebar 11 is further embedded in the pile member 3. At least the lower end side 11b of the joint rebar 11 is embedded in the pile member 3 in an arrangement of the pile main reinforcement 13 and the lap joint, and the upper end side 11a is fixed to the footing 4 serving as a fixed end. Moreover, the joining part reinforcement 11 is made into the adhesion cut part P which the lower end side 11b does not adhere to the pile concrete 12 in the partial range of the pile head 3a periphery.

  The joint rebar 11 is basically a member on the side where the adhesion cut portion P is formed at the boundary between the pile head 3a of the pile member 3 which is a joint and the lower surface of the footing 4, which is the pile member 3 in this embodiment. It bears a part of the compressive stress and tensile stress caused by the generated bending moment.

  In the figure, the joint reinforcing bars 11 are arranged for all the pile main bars 13, but may be arranged for a part of the pile main bars 13. The length of the joint rebar 11 may be appropriately set as long as the length exceeds the periphery of the pile head 3 a of the pile member 3 from the footing 4. In the illustrated example, the footing 4 is set so as to reach the lower side than the pile head 3a.

  In the present embodiment, the length relationship between the joint rebar 11 and the decompression rebar 10 is the same fixing length in the footing 4, and the joint rebar 11 is inside the pile member 3 more than the decompression rebar 10. It is set to be long. However, the length relationship between the joint rebar 11 and the decompression rebar 10 may be appropriately set according to the result of stress analysis. That is, the rebar 10 for decompression has a function to bear the stress in the pile axis direction in the region where the large compressive stress is unevenly distributed inside the pile member 3, and the joint rebar 11 increases the resistance of the joint. Therefore, the length relationship may be set in accordance with the performance to be exhibited by each. The bar arrangement work of the joint rebar 11 may be performed in the same manner as the bar arrangement work of the decompression rebar 10.

  Next, the effect | action of the junction structure of RC member concerning 5th Embodiment is demonstrated. The operation of joining the pile member 3 to the footing 4 is simply adding and placing the decompression reinforcing bar 10 and the joining part reinforcing bar 11, and can be constructed by various well-known methods.

  When the pile member 3 receives an earthquake force from the lateral direction while bearing an axial force, a bending moment is generated in the pile head 3a. Due to this bending moment, in the plane cross section of the pile head 3a, one becomes the tension side and the other becomes the compression side, and a hinge is generated. That is, the pile member 3 has a region in which a large compressive stress is unevenly distributed in the plane cross section.

  In the fifth embodiment, the upper end portion 10b is fixed to the footing 4 in this region of the pile member 3, and the decompression rebar 10 that bears the axial stress is arranged, so that the compressive stress is unevenly distributed. Can be borne by the pressure-reducing reinforcing bar 10 that resists this, and the stress is passed to the footing 4 side, which is the fixed end, so that the compressive stress received by the pile main bar 13 and the pile concrete 12 can be relieved.

  In this way, the decompression rebar 10 fixed on the footing 4 side can bear the compressive stress including the building foundation, so that the collapse at the pile head 3a is delayed and the occurrence of the collapse is prevented. can do. Thereby, the bending strength of the pile member 3 can be maintained longer. Moreover, since crushing generation | occurrence | production can be prevented, a cross-sectional defect | deletion does not arise in the pile member 3, but the axial direction yield strength of the pile member 3 can also be maintained.

  Moreover, since the adhesion cut part P which makes a reinforcing bar expand and contract in a pile axial direction was provided, and the joint part reinforcement 11 which bears both a compressive stress and a tensile stress was additionally provided, the reinforcing bar 10 for pressure reduction is acting. Under the circumstances, the resistance force at the joint between the pile member 3 and the footing 4 serving as the fixed end can be increased, thereby effectively transferring the stress load to the rebar 10 for decompression, and the pile member 3 and the footing 4. It is possible to more effectively prevent damage to the pile member 3 due to the occurrence of hinges around the joint.

  As described above, even in the RC member joint structure according to the fifth embodiment, the super high-strength concrete as described in the background art, taking into account the joint structure of the pile member 3 and the footing 4 Without presupposing the adoption of, the stress due to the bending moment, which is the cause of crushing, is effectively reduced by focusing on the location where the hinge occurs or the location where concrete crushing can occur significantly before the hinge occurs be able to.

  Moreover, when constructing the joint structure, it is only necessary to additionally arrange the decompression rebar 10 and the joint rebar 11 to the pile rebar rod 15, and the pile member 3 can be crushed with low cost and good workability. Can be prevented. Since the decompression reinforcing bar 10 is arranged inside the hoop reinforcement 14, it is possible to prevent the pile member 3 from being collapsed while preventing complication with the pile main reinforcement 13 and preventing the reinforcement work from being complicated.

  6 and 7 show sixth and seventh embodiments. These embodiments are RC member joint structures corresponding to the third and fourth embodiments, with the pile member 3 as a target. In these embodiments, the joint rebar 11 of the fifth embodiment is omitted.

  In FIG. 6, as in the above embodiment, the decompression rebar 10 is attached to the concrete as a whole, whereas in FIG. 7, the decompression rebar 10 has a lower end portion 10 a side at the bottom of the footing 4 and a pile member. 3 is defined as an unconstrained expansion / contraction part Q in a partial range around the lower pile head 3a with the joint position as a boundary.

  By forming the unconstrained expansion and contraction portion Q in this manner, the decompression rebar 10 is in a non-constrained expansion and contraction range while the range attached to the concrete excluding the unconstrained expansion and contraction portion Q follows the deformation of the pile member 3 and the like. Even if the part Q is freely expanded and contracted in the pile depth direction within that range and yields a hinge caused by a bending moment, both compression stress and tensile stress in the pile axis direction are more effective. Can be paid.

  Although not shown, an unconstrained expansion / contraction portion Q may be provided in the decompression rebar 10 of the fifth embodiment.

  FIG. 8 shows an eighth embodiment. In the eighth embodiment, in addition to the configuration of the fifth embodiment, a reduced-diameter portion 16 whose outer diameter dimension is smaller than the other portion of the pile member 3 is formed in the upper portion of the pile head 3a. . The reduced diameter portion 16 is formed concentrically with the pile member 3 so as not to protrude outward from the outer periphery of the pile member 3. Thus, an annular gap V is formed along the circumferential direction of the pile member 3 between the footing 4 and the pile member 3 with the reduced diameter portion 16 interposed therebetween. This gap V prevents the pile head 3a of the pile member 3 from being pressed against the lower surface of the footing 4 when the pile head 3a of the pile member 3 is subjected to a rotating action due to a bending moment, and this also crushes. Can be prevented.

  In addition, the pile head 3 a of the pile member 3 is narrowed by the reduced diameter portion 16 and the stress increases, but the resistance force between the pile head 3 a and the footing 4 by the adhesion cut portion P of the joint rebar 11. The stress around the reduced diameter portion 16 can be borne by the joint rebar 11 and the soundness of the pile member 3 can be ensured. Although not shown, an unconstrained expansion / contraction portion Q may be provided in the decompression rebar 10 according to the eighth embodiment, whereby the stress relaxation effect on the periphery of the reduced diameter portion 16 can be further improved.

  Furthermore, as a modification of the above embodiment, as shown by a two-dot chain line Z in FIGS. 4 and 5, a convex spherical portion is formed at the lower end of the RC column member 1 and the upper end of the pile member 3, and the floor slab 5 A corresponding concave spherical surface portion may be formed on the upper surface or the lower surface of the footing 4 so as to absorb the rotational action caused by the bending moment. At this time, the convex spherical surface portion and the concave spherical surface portion are preferably set in a shape that does not cause damage such as crushing to the RC column member 1 or the pile member 3 by a rotating action.

  FIG. 9 shows a plan of a preferred embodiment of a building according to the present invention. In the present embodiment, the RC member joining structure shown in the first to eighth embodiments is applied to the joining of at least some of the RC members arranged on the outer periphery of the building and the fixed end. In the illustrated example, a planar rectangular building S is shown.

  As shown in FIG. 11, when the high-rise portion of the building e is horizontally displaced so as to protrude outward from the low-rise portion due to the seismic force, the column member 9 on the outer periphery of the building e is caused by the bending moment generated thereby. Axial force increases significantly with pile members. And in the plane cross section of the pillar member g etc. of these building e outer periphery, compressive stress is unevenly distributed in the area | region which faces the building e outer side.

  In the present embodiment, the corner pillar member J and the side pillar member K located on the outer periphery of the building S, and the pile member located immediately below the four corners of the outer periphery of the building S and the outer peripheral position, although not shown in the drawings, The RC member joining structure according to the embodiment is applied. For example, with respect to the side column member K, the decompression rebar 10 is arranged facing the outside of the building S. The corner post member J also faces the outside of the building S, and the decompression reinforcing bars 10 are arranged in an L-shaped arrangement. Moreover, the joint part reinforcement 11 is also arrange | positioned as needed. For the column member L in the back of the building S, the RC member joint structure according to the above embodiment may be applied as necessary. Further, in this embodiment, the decompression reinforcing bars 10 are arranged on all the column members J, K on the outer periphery of the building S. However, the reinforcement members 10 may be arranged on some of the column members J, K. Of course it is good.

  When the action of the building S according to the present embodiment is described, a large bending moment is generated in each column member J, K, L of the building S, in particular, the column members J, K on the outer periphery due to the seismic force acting in the lateral direction. As a result, a hinge is generated. On the other hand, in this embodiment, the RC including the decompression reinforcing bar 10 and the joint reinforcing bar 11 according to the above embodiment on at least some of the column members J, K and pile members arranged on the outer periphery of the building S. Since the joining structure of the members is applied, compressive stress and tensile stress can be borne, and it is possible to prevent the outer peripheral column members J and K and pile members from being crushed and the occurrence of cross-sectional defects, and the soundness of the building S Can be improved.

  In the illustrated example, the planar rectangular building S has been described as an example. However, even in the case of a planar plan building S having a U shape, a square shape, or other planar outline, The same effect can be obtained by applying to at least some of the column members J, K and pile members arranged on the outer periphery of the building S along the outer contour.

  In the above embodiment, the RC column member 1 and the pile member 3 on the first floor of the building have been illustrated and described. However, in the case of the column member on each floor, the building is connected to the joint with the column beam joint. What is necessary is just to apply to the junction part with the said roof slab between the pillar head of the pillar member of a top floor, and a roof slab. In addition, if it is a place where the column base of the RC column member is joined to the fixed end, the above configuration is also applied to the so-called tension side column, the outer peripheral column of the building that bears the seismic force on the core wall, etc. By applying it, the soundness of the building can be improved.

  For example, the present invention can be similarly applied to a wall pile member such as a wall pile with a node. Even if it is a wall member, it can apply similarly with respect to joining with the beam and floor slab to which an upper end part and a lower end part are joined. In any of these examples, as in the above embodiment, part of the stress generated between the structural material and the fixed end can be borne by the decompression rebar, effectively preventing damage such as crushing. can do.

It is explanatory drawing explaining 1st Embodiment of the junction structure of RC member concerning this invention. It is explanatory drawing explaining 2nd Embodiment of the junction structure of RC member concerning this invention. It is explanatory drawing explaining 3rd Embodiment of the junction structure of RC member concerning this invention. It is explanatory drawing explaining 4th Embodiment of the junction structure of RC member concerning this invention. It is explanatory drawing explaining 5th Embodiment of the junction structure of RC member concerning this invention. It is explanatory drawing explaining 6th Embodiment of the junction structure of RC member concerning this invention. It is explanatory drawing explaining 7th Embodiment of the junction structure of RC member concerning this invention. It is the schematic front view which showed the reinforcement arrangement | positioning around a pile head which shows 8th Embodiment of the junction structure of RC member concerning this invention. It is a figure which shows the plane plan of the building using the junction structure of RC member concerning this invention. It is a schematic enlarged view of the column base part periphery for demonstrating the subject in background art. It is a schematic side view of the building for demonstrating the subject in background art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 RC column member 1a Column base 2 Foundation beam 3 RC pile member 3a Pile head 4 Footing 5 Floor slab 7 Column main reinforcement 8,14 Hoop reinforcement 10 Reinforcing bar 11 Joint reinforcement 13 Pile main reinforcement 16 Reduced diameter part J Corner column member K Side column member P Adhesion cut part Q Unconstrained expansion and contraction part S Building

Claims (5)

  A reinforced concrete member in which a main bar and a hoop bar are embedded, and a pressure-reducing reinforcing bar bearing an axial stress is embedded in a region on the inner side of the hoop bar and where a large compressive stress is unevenly distributed, is used for the pressure reduction. A joining structure of a reinforced concrete member, wherein a fixing end of a reinforcing bar is fixed to a fixed end and joined to the fixed end.   The reinforced concrete member joining structure according to claim 1, wherein the decompression rebar is not attached to concrete at a material shaft end portion of the reinforced concrete member.   The reinforced concrete member has one end side embedded in the arrangement of the main reinforcing bar and the lap joint, and the other end side has a joint rebar fixed to the fixed end, and the joint rebar has one end side of the material of the reinforced concrete member. The reinforced concrete member joining structure according to claim 1, wherein the reinforced concrete member is not attached to concrete in a partial range around the shaft end.   The reinforced concrete member is a concrete pile member, and the outer diameter dimension of the upper portion of the pile head of the concrete pile member is formed by reducing the diameter of the other portion than the other portion. 3. A joint structure of reinforced concrete members according to any one of the items.   The building characterized by using the joining structure of the reinforced concrete member in any one of Claims 1-4 for joining at least one part reinforced concrete member arrange | positioned at the building outer periphery, and a fixed end.

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