JP4423643B2 - Steel bar withdrawal prevention structure at the PC steel bar anchoring end - Google Patents

Description

  The present invention mainly relates to a structure for preventing the extraction of a steel bar at a fixed end of a PC steel bar in a prestressed concrete structure.

  Conventionally, as a PC tension material for introducing prestress into a prestressed concrete structure (hereinafter referred to as PC structure), its handling is easy, there is no set loss due to fixing, and tension management is easy. PC steel bars are widely used for some reason.

  As shown in FIG. 5, the fixing of the PC steel bar 1 passes through the bearing plate 3 fixed to the concrete structure 2, and the end of the PC steel rod 1 protruding from the surface of the bearing plate 3 is connected to the tension bar 4. The tension bar 4 is tensioned by the center hole jack 6 by taking the reaction force against the bearing plate 3 via the ram chair 5 and pulling it with the center hole jack 6, and in this state the fixing nut 7 is It is done by tightening.

  The fixing work space 8 formed in a continuous arrangement with the PC insertion hole 2 is backfilled with a mortar 9 or the like after the PC steel rod 1 is fixed to the bearing plate 3 as shown in FIG.

  However, in the conventional technology as described above, when corrosion occurs in a part of the PC steel bar and stress concentration occurs in that part and breaks at once, the backfilling of mortar or the like in which the PC steel bar is filled in the fixing work space There was a problem that there was a risk of breaking through the part and jumping out of the structure.

  On the other hand, in order to avoid the problems as described above, thorough management of the grout filled around the PC steel rod is performed to ensure the rust-proof coating of the PC steel rod, or regular non-destructive inspection is performed. Therefore, measures such as preventing breakage were necessary.

  Furthermore, as a method of avoiding the above-described problems, when the fixing work space is deeply formed and the amount of mortar to be filled is increased to increase the strength of retaining the PC steel rod, There is a problem in that a portion where no prestress is introduced occurs at the end portion and the proof stress of the entire structure is lowered.

  In view of the above-described conventional problems, an object of the present invention is to provide a structure for preventing the steel bar from being pulled out at the fixing end of the PC steel bar, which can prevent the PC steel from coming off with a simple structure.

In order to solve the above-mentioned conventional problems and achieve the intended purpose, the feature of the steel bar withdrawal preventing structure at the fixed end of the PC steel bar according to claim 1 is separated from the concrete structure. An improperly installed bearing plate, a PC steel bar penetrating through the bearing plate, and a fixing tool fixed to the outer periphery of the PC steel bar and supported on the outer surface side of the bearing plate, A support member that is integrally provided at the outer peripheral side of the fixing tool and protrudes from the support plate at a fixing end portion of the PC steel rod supported on the outer surface side of the support plate in a tension state via And a stop member supported on the tip side of the support member so as not to be pulled out, and the support plate is provided with an anchor extending into the concrete structure and embedded therein, and the support member is cylindrical. Outside the bearing plate of the fixing tool and PC steel rod The protruding end is accommodated, a female screw is formed on the inner peripheral surface, the male screw is formed on the outer periphery, and is screwed into the female screw so that it cannot be pulled out into the support member. The stopper member is shielded from the extending direction side of the tip of the PC steel bar, and the stopper member prevents the PC steel bar from popping out when it breaks.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the stopper member is fixed to the support member at that position by screwing and tightening the stopper member to a position where it comes into contact with the tip of the PC steel rod. There is in being.

A feature of the invention described in claim 3 is that, in addition to the structure of claim 1 or 2, the grout is filled in the gap on the side of the bearing plate from the stop member in the support member.

  The steel rod withdrawal preventing structure at the fixing end of the PC steel rod according to the present invention includes a bearing plate that is installed so as not to be detached from the concrete structure, a PC steel rod that penetrates the bearing plate, and the PC steel. Fixing tool fixed to the outer periphery of the rod and supported on the outer surface side of the bearing plate, and fixing the PC steel rod to the outer surface side of the bearing plate in a tensioned state via the fixing tool A support member that is provided at the end of the fixing device so as to project integrally from the pressure-bearing plate at a position on the outer peripheral side of the fixing tool, and a stop member that is supported on the distal end side of the support member so as not to come out. By shielding the end of the PC steel rod in the direction of the tip extension, even if the PC steel rod breaks halfway, the stop member is supported rigidly by the concrete structure via the support member and the bearing plate. Because it is, it is pressed by the stop member and PC tension It is possible to prevent the get out.

  The support member is formed in a cylindrical shape in which the fixing tool and the projecting end portion of the PC steel rod are supported outside, and the fastening member is screwed into a female screw provided on the inner surface of the support member. By making it impossible to pull out, the stop member can be fixed to the support member with a simple structure.

  By forming the PC steel rod end fixing work space formed at the end of the concrete structure into a cylindrical shape having substantially the same diameter as the inner diameter of the cylindrical support member, the space can be reduced. Prestress can be suitably introduced to the end of the concrete structure, and problems such as peeling of the backfill portion can be prevented.

  By filling grout into the gap on the side of the bearing plate from the stop member, the PC steel rod can be suitably rust-prevented.

  The pressure bearing plate is preferably fixed to the concrete structure so as not to be detached by being provided with an anchor extending into the concrete structure integrally projecting on the inner surface side thereof.

  The fixing tool is a nut screwed into a male screw formed at the tip of a PC steel rod, so that it can be easily handled and there is no set loss due to fixing, and the tension can be easily managed.

  Next, the steel bar extraction preventing structure at the fixing end of the PC steel bar according to the present invention will be described with reference to the drawings.

  FIG. 1 shows an outline of a fixing end portion of a PC steel rod, and reference numeral 10 in the drawing denotes a concrete structure.

  This concrete structure 10 has a PC insertion hole 12 through which a PC tension member 11 for introducing prestress is inserted, tensions the PC tension member 11 inserted through the PC insertion hole 12, and the PC tension. The end of the material 11 is fixed to a fixing bracket installed at the end of the concrete structure 10 and is supported on the end of the concrete structure 10 via the fixing bracket, thereby prestressing the entire structure 10. Is supposed to be introduced.

  The PC tension member 11 is composed of a PC steel bar having a threaded portion 14 at the end. The PC steel rod 11 penetrates the bearing plate 13 of the fixing bracket, and in the tensioned state, a fixing nut 15 is attached to the threaded portion 14. By tightening, the end of the PC steel rod 11 is fixed to the bearing plate 13.

  As shown in FIG. 2, the fixing bracket has a flat plate bearing plate 13 having a PC through-hole 16 in the center, a support member 18 projecting integrally from the outer surface of the bearing plate 13, and cannot be pulled out to the support member 18. The fixing member 15 fixes the end of the PC steel rod 11 to the bearing plate 13 by the fixing tool 15, and the stopper member 22 shields the tip extension side of the PC steel rod 11. Yes.

The support plate 13 is formed in a flat plate shape having a PC through-hole 16 through which the PC tendon 11 is penetrated in the center, and includes anchors 17 extending into the concrete structure 10 at the four corners and embedded therein. Thereby, the bearing plate 13 is installed so as not to be detached from the concrete structure 10.

  Further, a cylindrical support member 18 is integrally projected on the outer surface of the bearing plate 13, and the support member 18 is supported on the inner surface of a fixing work space 19 formed continuously with the PC insertion hole 12. ing.

  The supporting member 18 is formed in a cylindrical shape made of steel in which the fixing tool 15 and the protruding end portion of the supporting steel plate 11 of the PC steel rod 11 are housed, and one end edge thereof is welded to the outer surface of the supporting plate 13. Is arranged on the outer peripheral side of the PC tendon 12, and its central axis projects from the surface of the bearing plate 13 so as to coincide with the central axis of the PC insertion hole 12.

  Further, as shown in FIG. 3, a female screw 20 is formed on the inner peripheral surface portion of the support member 18, and a disc-shaped stop member in which a male screw 21 is formed on the outer periphery of the inner peripheral portion of the support member 18. 22 is screwed and fixed so that it cannot be pulled out.

  The fixing member 22 is fastened to a position where it abuts against the tip of the PC tension member 11 when the PC tension member 11 is fixed to the bearing plate 13, and is fixed to the support member 18 at that position. .

  Further, grout injection holes 23 are formed on both sides of the stopper member 22, and the grout 24 is filled into the support member 18 through the grout injection holes 23. In the figure, reference numeral 23a denotes a closing rod for closing the grout injection hole 23.

  In this way, the fixing bracket is installed at the end of the concrete structure 10, and the PC steel in which the end of the PC steel rod 11 that is tensioned to the bearing plate 13 of the fixing bracket is supported via the fixing tool (fixing nut) 15. At the fixing end of the rod 11, a stop member 22 is fixed to the support member 18, and the stop member 22 shields the support member 18, the bearing plate 13, and the anchor member 17 by shielding the distal end extension side of the PC steel rod 11. Since the PC tension member 11 is broken in the middle, the PC tension member 11 is pressed by the stop member 22 so as not to jump out. It has become.

  Further, a mortar 25 or the like is placed on the side of the surface of the fixing member 22 in the fixing work space 19 to be backfilled.

  In the fixing work space 19, since the PC tendon 11 is prevented from coming off by the stopper member 22 as described above, the thickness of the backfill portion such as the mortar 25 can be reduced and the fixing work space 19 can be made smaller.

  Next, a PC steel rod fixing method at the fixing end portion having the above-described PC steel rod retaining structure will be described.

  FIG. 3 shows a state when prestress is introduced into the concrete structure 10, and reference numeral 30 in the figure denotes a PC tension material tensioning device.

  The tension device 30 includes a ram chair 31 supported on the end surface of the concrete structure 10, a center hole jack 32 supported by the ram chair 31, and a tension bar 33 held by the center hole jack 32. By connecting the front end of the bar 33 to the end of the PC steel bar 11, taking a reaction force on the surface of the concrete structure 10 via the ram chair 31 and pulling the tension bar 33 by the center hole jack 32, the PC steel bar 11 is going to be tense.

  The ram chair 31 has a top plate 35 having a bar insertion hole 34 through which the tension bar 33 is inserted in the center, and a peripheral wall 36 that supports the periphery of the top plate 35, and one end portion (concrete structure 10 side) thereof. It is formed in an open cylindrical shape.

  A hexagon sleeve 37 is disposed outside the tension bar 33, and the fixing nut 15 is tightened using the hexagon sleeve 37.

  In addition, an opening / closing window 39 through which a wrench 38 for rotating the hexagonal sleeve 37 and tightening the fixing nut can be put in and out is formed at the lower end of the peripheral wall 36 of the ram chair 31.

  The tension bar 33 is formed with a screw hole 40 into which the screw portion 14 of the PC steel bar 11 is screwed, and the screw bar 14 of the PC steel rod 11 is screwed into the screw hole 40 to thereby fix the tip of the tension bar 33. The PC steel rod 11 can be connected to.

  In order to fix the PC tendon 11 using this apparatus 30, first, the PC steel rod 11 is inserted into the PC insertion hole 12 of the concrete structure 10, and the PC is placed on the surface side of the bearing plate 13 through the PC through hole 16. The end of the steel bar 11 is protruded, and a fixing nut 15 is screwed into the screw part 14 at the end of the PC steel bar 11.

  Next, after inserting the hexagon sleeve 37 into the support member 18 and fitting it outside the fixing nut 15, as shown in FIG. 3, the lower end of the ram chair 31 is supported on the end surface of the concrete structure 10, The tension bar 33 is inserted into the bar insertion hole 34 so that the center hole jack 32 is supported by the top plate 35 of the ram chair 31 and the tensioning device 30 is installed. Connect to the end of the rod 11.

  Then, a reaction force is applied to the concrete structure 10 via the ram chair 31, and a tension bar 33 is pulled by the center hole jack 32, thereby applying tension to the PC steel bar 11.

  By doing so, a gap is generated between the fixing nut 15 and the bearing plate 13, so the hexagonal sleeve 37 outside the tension bar 33 is rotated in the tightening direction, and the fixing nut 15 is tightened. 11 is fixed to the bearing plate 13.

  Next, the tensioning device 30 is removed, and the stopper member 22 is screwed into the inner side of the support member 18 until it contacts the tip of the PC steel rod 11, and the stopper member 22 is supported by the support member 18 so that it cannot be removed. This shields the end of the PC steel rod 11 in the direction of extension.

  At that position, grout is filled into the support member 18 from the grout injection hole 23 of the stopper member 22.

  When the grout filling is completed, the grout injection hole 23 is closed with a closing rod 23a, and thereafter, the mortar is filled in the outer portion of the fixing work space 19 from the stop member 22 and is then backfilled.

  Finally, the back-filled concrete is sufficiently cured to complete the end fixing of the PC tendon 11.

  In the above-described embodiment, the example in which the fixing nut 15 is used as the fixing tool has been described. However, other examples such as a wedge using a tapered cylindrical body divided vertically may be used.

  Moreover, although the example which formed the supporting member in the cylindrical shape was demonstrated in the above-mentioned Example, you may comprise a supporting member by the some bar | burr etc. which protruded from the bearing plate surface.

  Further, in the above-described embodiment, the example in which the stop member is screwed to the inner peripheral portion of the support member has been described. Alternatively, the stop member may be fixed to the inner portion of the support member by welding or the like.

It is sectional drawing which shows the outline of the PC tendon end part fixing structure which concerns on this invention. It is a disassembled perspective view which shows the outline of the fixing metal fitting in FIG. It is a partial expanded sectional view which shows the fixed state of the stop member in FIG. It is sectional drawing which shows the state of a prestress introduction process same as the above. It is sectional drawing which shows the outline of the prestress introduction | transduction process in the edge part fixing structure of the conventional PC tendon material. It is sectional drawing which shows the edge part fixing structure of PC tension material same as the above.

10 Concrete structure 11 PC tension material (PC steel bar)
12 PC insertion hole 13 Supporting plate 14 Screw part 15 Fixing nut 16 PC through hole 17 Anchor member 18 Support member 19 Fixing work space 20 Female screw 21 Male screw part 22 Stopping member 23 Grout injection hole 24 Grout 30 Tension device 31 Ram chair 32 Center hole jack 33 Tension bar 34 Bar insertion hole 35 Top plate 36 Perimeter wall 37 Hexagon sleeve

Claims (3)

A bearing plate installed so as not to be detached from the concrete structure, a PC steel bar penetrating through the bearing plate, and a fixing tool fixed to the outer periphery of the PC steel rod and supported on the outer surface side of the bearing plate And a PC steel bar fixing end part that supports the PC steel bar in a tensioned state on the outer surface side of the bearing plate through the fixing tool,
A support member integrally projecting from the support plate at a position on the outer peripheral side of the fixing tool, and a stop member supported so as not to be pulled out on the distal end side of the support member,
The bearing plate includes an anchor extending into the concrete structure and embedded therein,
The support member has a cylindrical shape, and the fixing tool and the PC steel rod projecting end outside the bearing plate are accommodated therein, and an internal thread is formed on the inner peripheral surface,
The stop member is formed with a male screw on the outer periphery, and is fitted into the support member so as not to be pulled out by being screwed into the female screw, and the front end extension side of the PC steel rod is shielded with the stop member,
A structure for preventing the steel bar from being pulled out at the fixing end of the PC steel bar, wherein the stopper member prevents the PC steel bar from popping out when it is broken . The steel rod removal at the fixing end portion of the PC steel rod according to claim 1, wherein the stopper member is fixed to the support member at the position by screwing and tightening to a position contacting the tip end portion of the PC steel rod. Outgoing prevention structure.   The steel rod withdrawal prevention structure at the PC steel rod fixing end portion according to claim 1 or 2, wherein a grout is filled in a gap on the side of the bearing plate from the stop member.