JP2005155058A - Beam member of rc structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a beam member of an RC structure in the vicinity of a column-beam joining part capable of freely forming a plastic hinge formed in a beam end part near the center of beams in a big earthquake. <P>SOLUTION: This beam member of the RC structure is constituted so that a plurality of joining reinforcements 3 and 3 are horizontally arranged in a connection part A of a column 1 by horizontally penetrating through this connection part A; a plurality of sleeves 4 and 4 are horizontally arranged in both end parts 3a and 3a of these joining reinforcements 3 as a steel pipe inside filling type joint; and main reinforcements 5 and 5 of the beams 2 and 2 and the joining reinforcements 3 and 3 are respectively joined via these sleeves 4 and 4. The sleeves 4 and 4 are respectively horizontally projected to both sides of the connection part A by the predetermined length L. A plurality of stirrup reinforcements 6 are wound between the sleeves 4 and 4 as shearing reinforcing bars, and are arranged at a predetermined interval in the axial direction of the sleeves 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a beam member having an RC structure in the vicinity of a column beam joint.

  In general, in the structural design of buildings, the stress of each member is calculated assuming the most adverse earthquake in terms of structural mechanics, and the cross section of each member is designed based on this stress. The bending stress is the largest at the beam end, and the beam center is extremely small compared to the beam end.

  The cross-sectional design of each member is, for example, in the case of RC structure beams, the amount of reinforcement at the beam end is designed against the large stress generated at the beam end. In many cases, the same amount of rebar is placed in the central part of the beam, which is less stressed than the end of the beam. Necessary reinforcing bars will be arranged.

  Also, when designing columns and beams, the column and beam are designed to realize a presumed yield mechanism of beam bending yielding based on the design philosophy of preventing brittle fracture of buildings during a large earthquake and protecting human lives from large earthquakes. The beam cross-section is being designed.

  In order to realize this design concept, the beam end portion is designed to form a plastic hinge at the time of a large earthquake, but this plastic hinge is required to have toughness that does not lower the yield strength even if it undergoes a large deformation.

In addition, in order to form a plastic hinge at the end of the beam in the event of a large earthquake, the beam end must have a proof strength less than that of the column. In the case where a through-hole for passing through is provided, if the reinforcing bars are arranged around the through-hole, the yield strength of the beam end portion is improved.
JP 2001-279811 A JP-A-11-81452 Japanese Patent Laid-Open No. 06-193196

  However, even if the amount of reinforcement at the center of the beam is small compared to the amount of reinforcement at the end of the beam, the amount of reinforcement at the center of the beam is for reasons such as simplifying the reinforcement work and improving workability. If the amount of bar arrangement at the end of the beam is the same, a mechanically unnecessary reinforcing bar will be arranged at the center of the beam, resulting in a very uneconomical problem.

  Also, when providing a through hole for piping at the end of the beam, if the end of the beam is reinforced by placing reinforcing bars around the through hole, the strength of the end of the beam is significantly higher than the strength of the column. Therefore, it is difficult to realize an assumed yield mechanism of the beam bending yield-preceding type, and it is difficult to provide a through hole for equipment piping at the beam end at the present time.

  The RC structure beam member according to claim 1, wherein a mechanical joint is provided on a beam main bar arranged at an end of the beam member in an RC structure beam member in the vicinity of a column beam joint, and the mechanical joint is provided. Is formed to have a predetermined length from the beam-column joint to the beam center side.

  In particular, the present invention provides a mechanical hinge on the beam main bar arranged at the end of the beam so that the plastic hinge formed at the beam end due to excessive stress during a large earthquake can be It can be easily formed near the tip of the mechanical joint from the center of the beam.

  Also, the amount of bar arrangement at the end of the beam should be designed not using the stress generated at the beam end as the design stress for the beam, but using the stress generated near the mechanical joint tip from the beam end to the center of the beam. Therefore, if the entire cross section of the beam including the central part of the beam is arranged in the same way as the bar arrangement at the end of the beam from the viewpoint of workability, etc., the total arrangement of the beam can be reduced. Construction costs can be reduced by reducing the amount of muscle.

  In addition, the beam reinforcement placed at the end of the beam is provided with a mechanical joint with a yield strength greater than that of the beam reinforcement, so that the plastic hinge can be attached to the end of the beam even under excessive stress during a large earthquake. It is not formed and the end of the beam remains in the elastic range, so that the toughness performance is not required at the end of the beam.

  In addition, since the strength of the beam is determined by the plastic hinge formed near the tip of the mechanical joint, even if the strength of the beam end increases due to reinforcement of the through-hole, the assumed yield mechanism of the beam bending yield precedence type It is maintained and does not become a problem.

  The RC structure beam member according to claim 2 is characterized in that, in the RC structure beam member according to claim 1, a joint having a higher yield strength than the beam main bar is provided as a mechanical joint.

  In the present invention, by using a joint having a higher yield strength than the beam main bar as a mechanical joint, the plastic hinge formed at the end of the beam in the event of a large earthquake is reliably formed from the end of the beam to a predetermined position from the center of the beam. In addition, the position of the plastic hinge can be freely set by setting the length of the mechanical joint.

  The RC structure beam member according to claim 3 is the RC structure beam member according to claim 1 or 2, wherein a threaded joint, a steel pipe crimping joint, or a steel pipe filling joint is provided as a mechanical joint. It is characterized by. In addition, mortar etc. can be used for the filler used in a steel pipe filling type joint.

  The RC structure beam member according to claim 4 is the RC structure beam member according to any one of claims 1 to 3, wherein a plurality of ribs are provided on the surface of the mechanical joint. It is.

  By providing ribs on the surface of the mechanical joint, not only can the adhesion performance of the concrete be remarkably improved, but also when placing the stirrup bars, the stirrup lines can be easily positioned and the workability is good. Moreover, it does not become an obstacle to securing the necessary cover thickness.

  The RC structure beam member according to claim 5 is the RC structure beam member according to any one of claims 1 to 4, wherein a through hole is provided at an end of the beam provided with the mechanical joint. It is characterized by.

  In the present invention, the end of the beam is reinforced by a mechanical joint to a strength substantially equal to that of the column beam joint, so that a through-hole for piping or the like is arranged at the end of the beam, in particular, a reinforcing bar. It can be provided without. Also, if reinforcement is required, it does not affect the assumed yield mechanism of the building.

  The present invention requires a plastic hinge formed at the beam end when it receives an excessive seismic force during a large earthquake by providing a mechanical joint on the beam main bar arranged at the beam end. Accordingly, it can be easily formed at a predetermined position from the beam center from the beam end.

  Also, instead of the stress at the beam end as the design stress for the beam, the stress generated near the mechanical joint tip from the beam end to the center of the beam is used, and the bar arrangement at the beam end is designed based on this stress. This makes it possible to reduce the total amount of beam reinforcement even if the entire cross section including the central part of the beam is arranged in the same way as the reinforcement at the beam end from the viewpoint of workability, etc. Cost can be reduced by reducing the amount of bar arrangement.

  In addition, since the ribs are provided on the surface of the mechanical joint, not only can the adhesion performance of the concrete be remarkably improved, but also when the stirrup bar is placed, the stirrup bar can be easily positioned. Workability is good.

  In addition, since the mechanical joint is provided in the beam main bar arranged at the end of the beam, the beam end stays within the elastic range without forming a plastic hinge even during a large earthquake, Toughness performance is not required at the beam end.

  Further, since the proof strength of the beam is set by a plastic hinge formed near the tip of the mechanical joint, there is no particular problem even if the proof strength of the beam end is increased by reinforcement around the through hole.

  Furthermore, if the beam member of the present invention is applied as a beam on each floor to a PCa column continuously formed as one column straddling a plurality of floors, a protruding member such as a joint metal fitting is projected on the beam member. Therefore, not only the assembly process of the shaft assembly can be simplified, but also the beam member can be transported and built smoothly.

  FIGS. 1A to 1C show PCa-structured beams arranged opposite to both sides of a column 1 having a precast (hereinafter referred to as “PCa”) structure and a joint portion (beam joint) A of the column 1. The junction part with 2 and 2 is shown.

  In the figure, a plurality of joint reinforcing bars 3 and 3 are horizontally laid through the joint A of the pillar 1 horizontally, and both ends 3a and 3a of the joint 3 are filled in the steel pipe. A plurality of sleeves 4, 4 are horizontally arranged as a type joint, and the main bars 5, 5 of the beams 2, 2 and the joining rebars 3, 3 are joined to each other via the sleeves 4, 4.

  The sleeves 4, 4 protrude horizontally on the both sides of the joint A by a predetermined length L, and a plurality of stirrup bars 6 are wound around the sleeves 4, 4 as shear reinforcement bars, whereby the shaft of the sleeve 4 is wound. The bars are arranged at predetermined intervals in the direction.

  In this case, the joint A and the end of the beam 2 can be obtained by arranging a thick reinforcing bar or a high-strength reinforcing bar as the joint rebar 3 of the joint A or increasing the amount of the joint rebar 3. The rigidity of the joint A and the end of the beam 2 is remarkably increased so that the portion does not brittle fracture prior to the column 1.

  Each sleeve 4 has a yield strength higher than that of the joining reinforcing bar 3 and the main reinforcing bar 5, and circular flange-like reinforcing ribs 4 a are formed on the outer circumference of each sleeve 4 at predetermined intervals in the axial direction of the sleeve 4. ing.

  Further, the stirrup muscle 6 is wound around the reinforcing ribs 4a and 4a of each sleeve 4 as shown in FIG.

  In this case, the main reinforcement 5 and the stirrup reinforcement 6 are made of round steel or deformed reinforcement, the sleeve 4 is made of cast iron pipe, and the reinforcing rib 4a of the sleeve 4 is integrally formed with the sleeve 4 body by casting. Or attached later by welding to the outer periphery of the sleeve 4 body.

  Further, after the joining reinforcing bars 3 and the main reinforcing bars 5 are joined to each other via the sleeve 4, concrete 7 is placed around the sleeve 4, the main reinforcing bars 5 and the stirrup reinforcing bars 6. The sleeve 4 is filled with mortar or the like as a filler for joining the joining rebar 3 and the main reinforcement 5.

In such a configuration, when designing the cross section of the beam 2, for example, as shown in FIG. 3, not the maximum stress (M ₁ ) generated at the end of the beam 2 but the sleeve slightly from the beam end to the center of the beam. 4, the stress (M ₂ ) generated near the tip of the beam 2 is used as the design stress of the beam 2, and the amount of reinforcing bars of the main reinforcement 5 and the stirrup reinforcement 6 at the end of the beam 2 is designed. By arranging the reinforcing bars 6 in the entire cross section of the beam 2 including the central portion of the beam 2, the amount of reinforcing bars arranged in the entire cross section of the beam 2 can be reduced.

  Further, the main reinforcement 5 of the beam 2 and the joining rebar 3 are joined by the sleeve 4 at the end of the beam 2, so that even if an excessive stress is generated in the beam 2 at the time of a large earthquake, the end of the beam 2 has an elastic range. The plastic hinge is formed in the vicinity of the end of the sleeve 4 slightly from the end of the beam 2 from the end of the beam 2 without forming the plastic hinge. Can be prevented.

  Further, by arranging the same amount of the main bar 5 and the stirrup bar 6 over the entire length of the beam 2 including the end and the center of the beam 2, the cross-section design and construction of the beam 2 can be made extremely easy. In addition, the amount of bar arrangement can be reduced and the cost can be reduced.

  FIG. 2 shows an example in which a through-hole 8 for piping is provided at the end of the beam 2. The through-hole 8 is formed horizontally between the upper and lower sleeves 4, 4, and reinforcing bars 9 are arranged around it. Has been. In this case, even if the periphery of the through-hole 8 is reinforced by the reinforcing bar 9 and the rigidity of the beam end is remarkably improved, the plastic hinge is formed from the end of the beam 2 to the vicinity of the end of the sleeve 4 slightly from the center of the beam. Therefore, the assumed yield mechanism of the beam bending yield-preceding type is maintained, and brittle fracture of the joint A and the end of the beam 2 can be prevented in advance.

  The invention of the present application is used for an RC structure column beam joint composed of an RC structure column and an RC structure beam.

(A) is a side view showing a beam-column joint portion of PCa structure, (b) is a side view of a mechanical joint, and (c) is a cross-sectional view taken along line II in (b). It is a side view which shows the column beam junction part of PCa structure. It is a stress figure of a column beam junction part.

Explanation of symbols

1 PCa structure column 2 PCa structure beam 3 Jointed rebar 4 Sleeve (mechanical joint)
4a Reinforcement rib (rib)
5 Beam main bar 6 Stirrup bar 7 Concrete 8 Through hole 9 Reinforcement bar A Joint

Claims (5)

  In the RC structure beam member in the vicinity of the beam-to-column joint, a mechanical joint is provided in the beam main bar arranged at the end of the beam member, and the mechanical joint has a predetermined length from the beam-to-column joint to the beam center side. An RC structure beam member characterized by being formed with a thickness.   The RC structure beam member according to claim 1, wherein a joint having a yield strength larger than that of the beam main bar is provided as a mechanical joint.   The RC structure beam member according to claim 1, wherein a threaded joint, a steel pipe crimping joint, or a steel pipe filling joint is provided as the mechanical joint.   The RC structure beam member according to any one of claims 1 to 3, wherein a plurality of ribs are provided on a surface of the mechanical joint. The beam member having an RC structure according to any one of claims 1 to 4, wherein a through hole is provided at an end of the beam provided with the mechanical joint.

Images