JP2010024659A - Structure for joining structural material and fixing end together - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure for joining a structural material and a fixing end together, 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 strength concrete, in consideration of the structural material and the fixing end to be connected to the structural material. <P>SOLUTION: A stress relaxing portion for partially releasing the stress generated between a reinforced concrete column and a floor slab is formed along an outer peripheral edge of a column base portion of the reinforced concrete column on the floor slab 8 to be joined to the column base portion 1a of the reinforced concrete column 1. The stress relaxing portion is a groove 9 which is arranged along the outer periphery of the column base portion. The groove can also be filled with a filler lower in compression strength or rigidity than the floor slab. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention takes into account the structural material and the fixed end to which it is joined, and does not assume the use of ultra-high-strength concrete, and places where the hinge generates stress due to bending moment that is the cause of crushing. Alternatively, the present invention relates to a joint structure between a structural member and a fixed end that can be effectively reduced by narrowing down to a portion where concrete collapse may occur significantly before the hinge is generated.

  The column member is a structural material that bears an axial force from above. For example, in an RC column on the first floor of a building, a column base that is a material end 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 a deformation due to a lateral seismic force, as shown in FIG. 8, the column base portion c of the RC column b joined to the fixed end a. 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.

  This kind of phenomenon can also occur in the column base portion of the column member on each floor where the column beam joint is a fixed end. For pillar members, in addition to this, the axial force is reduced by seismic force, so-called tension side pillars, even in outer peripheral pillars of buildings that are designed to bear seismic force on the core wall, etc. The same can be said. Furthermore, crushing can also occur between the column head of the column member on the top floor of the building and the roof slab to which it is joined.

  In addition to the pillar member, there are a pile member, a wall pile member, and a wall member as a structural material that bears an 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 structural material alone is used to prevent crushing or to take measures to improve toughness and durability, and it does not consider the fixed end to which the structural material is joined. However, there was a problem that the obtained structural performance was limited. 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 consideration the structural material and the fixed end to which it is joined, without causing the use of ultra-high-strength concrete, and the occurrence of crushing Bonding structure between structural material and fixed end that can effectively reduce the stress caused by the bending moment by focusing on the location where the hinge occurs or the location where concrete collapse can occur significantly before the hinge occurs The purpose is to provide.

  The structure-to-fixed-end joining structure according to the present invention is such that the structure material and the fixed end are joined to the fixed end joined to the material end of the structure material along the outer peripheral edge of the structure material. It is characterized in that a stress relaxation portion for releasing a part of the stress generated therebetween is formed.

  The stress relaxation part is a groove arranged along the outer periphery of the end of the structural material.

  The groove is filled with a filler having a compressive strength lower than that of the fixed end.

  The groove is filled with a filler having a rigidity lower than that of the fixed end.

  In the joining structure of the structural material and the fixed end according to the present invention, taking into account the structural material and the fixed end to which the structural material is joined, without causing the use of ultra-high-strength concrete, the cause of the occurrence of crushing It is possible to effectively reduce the stress caused by the bending moment by focusing on a portion where the hinge is generated or a portion where the concrete collapse may occur significantly before the hinge is generated.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a structure for joining a structural member and a fixed end according to the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a first embodiment of a structure for joining a structural member and a fixed end according to the present invention. In the first embodiment, the RC pillar 1 on the first floor of the building that bears the load from the upper floor will be described as an example of the structural material that receives the axial force from above.

  The structure of the RC column 1 itself is well known in the art, and the column main reinforcement 3 arranged in the column concrete 2 at intervals in the circumferential direction of the column, and the height of the column surrounding the column main reinforcement 3 It is formed by burying hoop muscles 4 arranged at intervals in the direction. The concrete material may be ordinary concrete, high-strength / ultra-high-strength concrete, or steel fiber, carbon fiber, resin fiber or the like mixed as a reinforcing material. Further, the RC pillar 1 may be a hollow outer shell precast concrete pillar member filled with filling concrete, solid precast concrete, or constructed by hitting concrete on-site. Good.

  In the figure, the periphery of the column base 1a which is the material shaft end of the RC column 1 is shown. In the vicinity of the column base 1a of the RC column 1 on the first floor of the building, a footing 7 is provided on the pile member 6 at the intersection of the foundation beams 5 arranged vertically and horizontally. A floor slab 8 on the first floor of the building is laid on the foundation beam 5. The foundation beam 5, the pile member 6, the footing 7, and the floor slab 8 are constructed with an RC structure. On the floor slab 8, the RC pillar 1 is provided by being raised on the footing 7 while being coupled to the foundation beam 5. The column base 1a which is the material shaft end of the RC column 1 may be joined using the foundation beam 5 including the floor slab 8 as a fixed end, or may be joined using the footing 7 as a fixed end. In the present embodiment, the foundation beam 5 including the floor slab 8 is a fixed end.

  On the upper surface of the floor slab 8 serving as a fixed end, along the outer peripheral edge of the column base 1a of the RC column 1, stress relaxation for releasing a part of the stress generated between the RC column 1 and the floor slab 8 is provided. As a part, a groove 9 is formed. Specifically, the outer peripheral edge of the column base 1a is a junction boundary B (see FIG. 3) with the column base 1a that appears on the upper surface of the floor slab 8. The groove 9 is arranged along the joint boundary B around the column base 1a, specifically, outside the joint boundary B.

  The groove 9 thereby divides the upper surface of the floor slab 8 and forms the column base portion peripheral portion 8a of the floor slab 8 surrounding the column base portion 1a (see FIG. 3). The groove 9 is formed by the occurrence of a hinge when a hinge caused by a bending moment generated in the RC column 1 by receiving a seismic force in the lateral direction while bearing an axial force is generated in the column base portion 8a. The space | gap which accept | permits the deformation | transformation D (refer FIG. 3) which a leg part peripheral part 8a presses with the RC pillar 1 and expands slightly, and thereby releases one part of the stress which generate | occur | produces between the RC pillar 1 and the floor slab 8 It becomes. The amount of deformation in which the column base portion peripheral portion 8a swells can be estimated by stress analysis.

  The inner diameter dimension of the inner periphery of the groove 9 causes the swelling deformation D generated in the column base peripheral portion 8a to be generated toward the inside of the groove 9, and thereby the stress is smoothly released. It is set slightly larger than the diameter dimension. The depth dimension of the groove 9 is set to an appropriate depth that allows the deformation D to expand. The outer diameter dimension of the groove 9 determines the groove width in relation to the inner diameter dimension, does not hinder the swelling D of the column leg peripheral portion 8a, does not impair the required strength of the floor slab 8, and is around the RC column 1. It is set as appropriate so as not to hinder the approach to. The groove 9 is preferably formed in advance on the floor slab 8 using a mold or the like so as to obtain high dimensional accuracy, but may be formed by rolling after the RC pillar 1 is installed. Good. Further, reinforcing materials such as reinforcing bars are not arranged in the column base portion peripheral portion 8a.

  In the present embodiment, as shown in FIG. 2, the groove 9 continues in an annular shape over the entire circumference of the RC column 1 along the flat cross-sectional outline of the RC column 1 at the upper surface position of the floor slab 8. It is formed. In the illustrated example, the RC pillar 1 has a rectangular cross-sectional outline, and therefore the groove 9 is also formed in a square shape. When the outer cross-sectional outline of the RC pillar 1 is circular or polygonal, the groove 9 is also formed in a circular or polygonal shape.

  In the present embodiment, the groove 9 is formed in a single continuous annular shape, but may be a plurality of grooves 9 formed intermittently around the RC pillar 1. When the groove 9 is intermittently formed, the periphery of the column base portion 1a is reinforced by the portion where the groove 9 is divided, as compared with the case where the groove 9 is formed continuously.

  The strength of the floor slab 8 is set to such a strength that the RC column 1 is not crushed by the stress remaining in the RC column 1 in which a part of the stress is released by the groove 9.

  Next, the effect | action of the joining structure of the structural material concerning this embodiment and a fixed end is demonstrated. As shown in FIG. 3A, in the normal state, the axial force applied from the upper floor flows from the RC pillar 1 on the first floor of the building as it is toward the pile member 6 directly below, and is supported by the ground. Therefore, at this normal time, the groove 9 as the stress relaxation portion formed in the floor slab 8 does not function and is the same as a general building.

  On the other hand, as shown in FIG. 3 (b), when a lateral seismic force is received while bearing an axial force, a hinge due to a bending moment is generated in the column base 1 a of the RC column 1. When this compression occurs, the compression-side column base part 1a exhibits a behavior of sinking into the column base part peripheral part 8a, so that stress increases at the joint boundary B between the column base part 1a and the floor slab 8, and accordingly, the groove 9 Further, the stress of the inner column base portion 8a also increases. Since the column base portion peripheral portion 8a faces the groove 9 which is a gap, a swelling deformation D corresponding to the increased stress occurs. That is, the groove 9 allows the deformation D that the column base portion peripheral portion 8a swells.

  In this way, by allowing the groove 9 to allow the deformation D in which the column base portion peripheral portion 8a swells to be allowed to occur, the bending boundary increases at the junction boundary B of the column base portion 1a and the floor slab 8, and consequently the column base portion 1a of the RC column 1. The resulting stress can be partially released. The column base portion peripheral portion 8a on the floor slab 8 side exhibiting the swelling deformation D can release stress smoothly by deformation in the elastic region or plastic region.

  And since the stress which increases in the column base part 1a can be partially released, even if the horizontal displacement of the RC column 1 proceeds as shown in FIG. The bending strength of the column 1 can be maintained, and the occurrence of crushing at the column base 1a can be delayed or the occurrence of crushing can be prevented. Thereby, the bending strength of RC pillar 1 can be maintained longer. In addition, since the occurrence of crushing can be prevented, the RC pillar 1 can be maintained in the axial direction yield strength without causing a cross-sectional defect.

  As described above, in the joint structure of the structural material and the fixed end according to the present embodiment, it is described in the background art in consideration of the RC pillar 1 and the floor slab 8 to which the RC pillar 1 is joined. Without stressing the use of ultra-high-strength concrete, the stress due to the bending moment, which is the cause of crushing, is limited to the location where the hinge occurs or where the concrete can be significantly collapsed before the hinge occurs It can be effectively reduced.

  Since the groove 9 is arranged along the outer periphery of the RC column 1, the occurrence of crushing can be prevented even if the hinge is generated in any direction around the RC column 1. When a plurality of grooves 9 are intermittently formed, the periphery of the column base portion 1a can be reinforced by a portion where the grooves 9 are divided, as compared with a case where the grooves 9 are formed continuously.

  In the above embodiment, the case where the foundation beam 5 including the floor slab 8 is used as the fixed end has been described, but even if the footing 7 is used as the fixed end, the groove 9 is formed in the same manner, Similar effects can be obtained.

  FIG. 5 shows a modification of the above embodiment. In the above embodiment, the groove 9 that forms a gap has been described. However, the groove 9 is filled with a filler 10 having a compressive strength or rigidity that is lower than the compressive strength of the floor slab 8 or the footing 7 serving as a fixed end. Also good. Examples of the low compressive strength filler 10 include mortar and wood whose strength is lower than that used for the fixed end. Examples of the low-rigidity filler 10 include foamed polyethylene and PVC hollow pipe.

  If these fillers 10 are filled in the grooves 9, a part of the stress that increases in the column base portion peripheral portion 8a can be borne by these fillers 10, and compared with the case where the grooves 9 are left as gaps, It is possible to improve the structural integrity of the column base portion peripheral portion 8a that causes the swelling deformation D. Further, by filling the groove 9 with the filler 10, the RC pillar 1 can be freely approached.

  6 and 7 show a second embodiment of the structure for joining a structural member and a fixed end according to the present invention. In 2nd Embodiment, the pile member 6 is shown as a structural material which receives axial force from upper direction. The pile member 6 may be of any conventionally known structure type / construction type, such as a ready-made pile or a cast-in-place pile.

  In the drawing, the periphery of a pile head 6a that is a material shaft end portion of the pile member 6 is shown. A footing 7 connected to the foundation beam 5 is joined on the pile head 6 a, and the footing 7 serves as a fixed end of the pile member 6. On the lower surface of the footing 7 that is a fixed end, as a stress relaxation part for releasing a part of the stress generated between the pile member 6 and the footing 7 along the outer peripheral edge of the pile head 6a of the pile member 6 A groove 9 similar to that of the first embodiment is formed.

  Specifically, the outer peripheral edge of the pile head 6a is a joint boundary C with the pile head 6a that appears on the lower surface of the footing 7. The groove 9 is arranged along the joint boundary C, around the pile head 6a, specifically outside the joint boundary C.

  The groove 9 forms a pile head peripheral portion 7a of the footing 7 surrounding the pile head 6a by dividing the lower surface of the footing 7 thereby. When the hinge 9 is generated in the peripheral portion 7a of the pile head due to the bending moment generated in the pile member 6 by receiving the lateral seismic force while bearing the axial force, The head peripheral portion 7 a is allowed to deform slightly swelled by being pressed from the pile member 6, thereby forming a space for releasing a part of the stress generated between the pile member 6 and the footing 7. The amount of deformation that the pile head peripheral portion 7a swells can be estimated by stress analysis.

  The dimensions set in the groove 9 are the same as those in the first embodiment. In other words, the inner diameter dimension of the groove 9 is such that the swelling deformation generated in the pile head peripheral portion 7a is generated toward the inside of the groove 9, and thereby the stress is smoothly released, thereby the outer diameter of the pile head 6a. It is set slightly larger than the dimensions. The depth dimension of the groove 9 is set to an appropriate depth that allows the swelling deformation. The outer diameter dimension of the groove 9 determines the groove width in relation to the inner diameter dimension, and is appropriately set so as not to hinder the swelling deformation of the pile head peripheral portion 7a and not to impair the required strength of the footing 7. The

  In this embodiment, as shown in FIG. 7, the groove 9 is continuously formed in an annular shape over the entire circumference of the pile member 6 along the flat cross-sectional outline of the pile member 6 at the bottom surface position of the footing 7. Is done. In the example of illustration, since the cross-sectional outline outline of the pile member 6 is circular, the groove 9 is also formed in a circular shape.

  In the present embodiment, the groove 9 is formed in a single continuous annular shape, but may be a plurality of grooves 9 formed intermittently around the pile member 6. When the groove 9 is formed intermittently, the periphery of the pile head 6a is reinforced.

  The strength of the footing 7 is set to such a strength that the pile member 6 is not crushed by the stress remaining in the pile member 6 in which a part of the stress is released by the groove 9.

  The effect | action of the joining structure of the structural material concerning 2nd Embodiment and a fixed end is the same as that of the said 1st Embodiment, By allowing the deformation | transformation which the pile head periphery part 7a swells by the groove | channel 9, the pile head 6a The stress caused by the bending moment increasing at the joint boundary C of the footing 7 and the pile head 6a of the pile member 6 can be partially released, and the occurrence of the collapse at the pile head 6a can be delayed or collapsed. Occurrence can be prevented. Moreover, since crushing generation | occurrence | production can be prevented, a cross-sectional defect | deletion does not arise in the pile member 6, but the axial direction yield strength of the pile member 6 can also be maintained.

  Even in the second embodiment, the groove 9 can be configured by being filled with a filler 10 having a lower compressive strength or rigidity than the footing 7, thereby obtaining the same effects as the above-described modification. be able to.

  In the above embodiment, the RC pillar 1 and the pile member 6 on the first floor of the building have been illustrated and described as the structural material. However, in the case of the pillar member on each floor, What is necessary is just to form the groove | channel 9 in a roof slab between the pillar head of the pillar member of a thing top floor, and a roof slab. In addition, if it is a place where the material shaft end portion of the column member is joined to the fixed end, the groove 9 can be provided even on a so-called tension-side column, an outer peripheral column of a building in which a seismic force is borne by the core wall, etc. By effectively releasing stress, the soundness of the building can be improved.

  For example, in the case of a wall pile member such as a wall pile with a knot, a groove 9 is formed along the front and back of the wall pile member at a fixed end such as a foundation beam 5 or a footing 7 to which the end portions of the material shaft are joined. That's fine. Even if it is a wall member, the groove | channel 9 should just be formed in the beam and floor slab to which an upper end part and a lower end part are joined along the front and back of the said wall member. In any of these examples, as in the above-described embodiment, a part of the stress generated between the structural material and the fixed end can be released by the groove 9, and the occurrence of damage such as crushing is effectively prevented. be able to.

  Furthermore, in the said embodiment, although the member made from RC was illustrated and demonstrated as a structural material, the member made from SRC may be sufficient. Furthermore, even in the case of the S-structured material, a part of the stress can be released by the groove 9 against the bending moment generated at the joint portion of the exposed material shaft end to the fixed end. Can prevent its damage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic front cross-sectional view of a periphery of a column base portion of an RC column showing a first embodiment of a joint structure between a structural member and a fixed end according to the present invention. It is a schematic plan view of the column base part periphery of RC pillar shown in FIG. It is explanatory drawing for demonstrating the stress relaxation effect | action in the column base part periphery of RC pillar shown in FIG. It is a graph which shows the relationship between the bending strength by the joining structure of the structural material concerning this invention, and a fixed end, and horizontal displacement. It is explanatory drawing explaining the modification of 1st Embodiment. It is a schematic front sectional drawing of the pile head periphery of the pile member which shows 2nd Embodiment of the joining structure of the structural material concerning this invention, and a fixed end. It is the schematic look-up figure which looked up the pile head periphery of the pile member shown in FIG. 6 from the footing bottom. It is explanatory drawing for demonstrating the subject in background art.

Explanation of symbols

1 RC column 1a Column base 6 Pile member 6a Pile head 7 Footing 8 Floor slab 9 Groove 10 Filler

Claims (4)

  Stress relaxation to release a part of stress generated between the structural material and the fixed end along the outer peripheral edge of the structural material at the fixed end joined to the structural material end. A structure of joining a structural material and a fixed end, characterized by forming a portion.   The said stress relaxation part is a groove | channel arrange | positioned along the outer periphery of the said structural material material edge part, The joining structure of the structural material and fixed end of Claim 1 characterized by the above-mentioned.   3. The structure-joining structure according to claim 2, wherein the groove is filled with a filler having a compressive strength lower than that of the fixed end.   The joining structure of a structural member and a fixed end according to claim 2, wherein the groove is filled with a filler having a rigidity lower than that of the fixed end.

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