JP3514579B2 - Prestress introduction unit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prestress introduction unit for introducing a compressive stress to a concrete member. 2. Description of the Related Art In a precast structure, a prestress is conventionally applied to a connecting portion for connecting a concrete member such as a column or a beam. In this case, a sheath pipe is previously added to the concrete member to be joined. By embedding such a material and forming a through hole, connecting concrete members at the construction site and inserting PC steel into the through hole, fixing the end of the PC steel material with a support plate, nut and washer, and jacking the nut etc. Introduce prestress by tightening with a tensioner. [0003] In the above-mentioned conventional PC steel material, all operations for introducing tension must be performed at a construction site. There is a problem that the tension introducing device becomes large, it is difficult to handle it in a narrow work space such as a scaffold, and further, it cannot be moved on a construction site unless a lifting machine such as a crane is used. [0004] Further, in the above-mentioned conventional PC steel material, a notch may be formed in some cases in order to arrange a supporting plate. However, there is a problem that the notch causes a structural cross-sectional defect, and reduces the structural strength of the concrete member. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional connecting structure, and an object of the present invention is to introduce a prestress into a concrete member by a simple operation at a construction site. To provide units. It is another object of the present invention to provide a prestress introduction unit which can partially omit a supporting plate for fixing a prestress member to a concrete member. Still another object of the present invention is to provide a prestress introduction unit which can reduce the diameter of a through hole formed in a concrete member and can be easily disposed in the through hole. [0008] The present invention has been made in view of the above-mentioned object, and a gist of the invention is a pre-stress introducing unit for introducing a compressive stress to a concrete member . A thread is formed on the inner periphery of the end , and the second
A cylindrical steel rod having a thread formed on the outer periphery of the end of
A full screw bolt screwed around the inner periphery of the first end of the shaped steel rod;
A steel rod inserted into the tubular steel rod to introduce a compressive force,
Detachable tension holding means for holding the compressive force introduced into the steel rod and transmitting the compressive force to the cylindrical steel rod as a tensile force, the tension holding means being provided at an inner periphery at one end.
A thread is formed and the other end is the second of the cylindrical steel rod.
A tubular coupler screwed around the outer periphery of the end;
So that it can be fitted into the puller and abut against the end of the steel bar
Interposed member movably provided on the member and abutting the interposed member
Thread on the inner circumference of the end of the tubular coupler
And a combined hollow bolt . In the prestress introduction unit according to the present invention, the entire screw bolt may be formed in a shape having no portion projecting from the outer shape of the cylindrical steel bar when screwed into one end of the cylindrical steel bar. If one end of the cylindrical steel rod is sealed with a full screw bolt of such a shape, it does not become an obstacle when the cylindrical steel rod is inserted into the through hole of the concrete member, and the through hole has a diameter of the cylindrical steel rod. It is not necessary to form the above and make the diameter larger than necessary. Further, the full screw bolt may be formed with a screw thread so that it does not come off from the cylindrical steel rod even if it receives a pressing force from a steel rod inserted into the cylindrical steel rod. That is, the steel rod is inserted into the cylindrical steel rod such that one end thereof is in contact with the full screw bolt, and is pressed from the other end to introduce a compressive stress. A pressing force is applied in the direction to pull out from the steel bar. Therefore, the entire screw bolt may be formed so as not to come off from the cylindrical steel bar against such a pressing force. [0010] In the prestress introduction unit of the present invention, a thread may be formed on the outer periphery of the other end of the cylindrical steel rod over a predetermined length. When it is inserted and arranged in the through hole, it may be formed so as to reach the inside of the through hole. By forming the screw thread in this way, it is possible to improve the performance of adhering to the concrete adhering to the outer surface of the cylindrical steel rod or mortar as a grout material to be back-filled. By improving the adhesion performance, even when compressive stress is introduced from the cylindrical steel bar to the concrete member on the outer periphery thereof, it is possible to prevent a phenomenon that only the cylindrical steel bar comes off. Therefore, fixing can be achieved only by inserting a tubular steel rod into the inside of the installation duct of the concrete member and filling grout such as mortar or concrete into the inside of the installation duct.
One of the support plates provided at both ends of the C steel material can be omitted. In the prestress introducing unit of the present invention, the steel rod is housed inside the cylindrical steel rod and receives a compressive force, and the compressive force can introduce a tensile force to the cylindrical steel rod. Anything is fine. In the prestress introduction unit of the present invention, when a compressive force is applied to a steel rod inserted into the cylindrical steel rod, the tension holding member reduces the restoring force of the compressed steel rod. Any member capable of transmitting the force to the cylindrical steel bar and thereby introducing a tensile force to the cylindrical steel bar may be used.For example, a screw thread may be engraved on the outer peripheral surface of one open end of the cylindrical steel bar. Nuts, bolts, and the like, which can be screwed into the thread and pressed on the steel bar by a jack device or the like to tension and hold the cylindrical steel bar, can be used. According to this aspect, the prestress introduction unit of the present invention removes the tension holding member at the construction site,
When the tensile force applied to the cylindrical steel bar is released, a compressive stress can be easily applied to the concrete member. In addition, when the prestress introduction unit is used when fixing at least a pair of concrete members, grout material or concrete can be adhered to the entire cylindrical steel bar and firmly integrated, and the prestressing unit can be preformed on each concrete member. Stress can be introduced to easily fix. In the prestress introduction unit of the present invention, the concrete member includes at least concrete,
A member formed including any of grout and mortar, for example, a pillar, a beam or a slab of a building, a girder or a slab of a bridge, a slab or a pontoon of a pavement. Embodiments of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited thereto.
Here, FIGS. 1 to 3 are cross-sectional views for explaining the configuration and manufacturing procedure of the prestress introduction unit of the present invention, and FIG. 4 is a cross-sectional view of the prestress introduction unit of the present invention. In FIG. 4, a prestress introduction unit 20 is a hollow steel rod formed as a cylindrical steel rod formed by threading an outer screw 21a on the outer periphery of one end and an inner screw 21c on the inner periphery of the other end. A rod 21, a full screw bolt 22 screwed into an inner screw 21c of the hollow steel rod 21, a solid steel rod 24 inserted into the hollow steel rod 21 to introduce a compressive force, Removable tension holding means (coupler 25, intervening member 26 and hollow bolt 27) for holding the compressive force introduced into the rod 24 and transmitting the compressive force to the hollow steel rod 24 as a tensile force are mainly used. Prepare. The hollow steel rod 21 is buried inside a sheath tube or the like provided in the concrete member to introduce a compressive stress as a prestress to the concrete member. The solid steel bar 24 is a hollow steel bar 2.
This is used to take a reaction force when a tensile force is applied to the first member. The full screw bolt 22 is formed by threading a screw thread 22a that can be screwed to the inner screw 21c of the hollow steel rod 21 over the entire outer circumference. In addition, the full screw bolt 22
Use a bolt without a bolt head. The coupler 25 has a screw thread 25b formed on the inner periphery of the front end portion which can be screwed to the outer screw 21a of the hollow steel rod 21, and a screw thread which can be screwed with the hollow bolt 27 on the inner periphery of the rear end portion. 25a is formed. The intervening member 26
Are formed so as to be insertable into the coupler 25, and are arranged so as to come into contact with the solid steel rod 24 when the coupler 25 is inserted into the coupler 25. Further, the hollow bolt 27 has, on its outer periphery, a thread 27a which can be screwed with the thread 25a of the coupler 25.
To form In the prestress introducing unit 20 having the above-described structure shown in FIG. 4, a tensile force is previously introduced to the hollow steel bar 21 in a factory or the like. That is, as shown in FIGS. 1 and 2, first, the entire screw bolt 22 is screwed to the inner screw 21 c of the hollow steel rod 21 to a length of about half, and the nut 23 is screwed to the outer screw 21 a. . Next, as shown in FIG. 3, the solid steel bar 24 is inserted into the hollow steel bar 21, and the coupler 25 is screwed into the outer screw 21 a to be brought into contact with the nut 23. The interposed member 26 is inserted and the hollow nut 27 a is screwed into the coupler 25 until the interposed member 26 comes into contact with the interposed member 26. Then, the nut 23 is fixed by some fixing means (not shown), and this is used as a reaction force in the direction of the arrow Q. In addition, the solid steel bar 24 is pushed into the hollow steel bar 21. At this time, the solid steel bar 24 is compressed and shortened in length,
On the other hand, the hollow steel bar 21, on the contrary to the solid steel bar 24, expands by receiving the compressive force applied to the solid steel bar 24 as a tensile force via the entire screw bolt 22, thereby forming an interposed member 26. A gap is formed between the hollow nut 27 and the hollow nut 27. In order to fill this gap, the hollow nut 27 is brought into contact with the interposed member 26.
Is further screwed, the hollow steel bar 21 is fixed in a stretched state by the introduction of a tensile force, and the solid steel bar 24 is fixed in a contracted state by the introduction of a compressive force. The pre-stress introducing unit 20 formed as described above, after fixing the hollow steel bar 21 to the concrete member, removes the hollow nut 27 with a torque wrench or the like, and causes the stress in the direction of contraction to the hollow steel bar 21 in the extended state. Acts, a compressive stress can be introduced into the concrete member by this stress. Next, a method of arranging the prestress introduction unit 20 on a concrete member will be described with reference to FIG. In FIG. 5, through holes are previously formed in the precast column 40 and the precast beam 42 as concrete members by a sheath tube or the like. First, the support plate 32 is passed through the prestress introduction unit 20 and is inserted into the through hole from the entire screw bolt 22, so that the entire screw bolt 22 is projected from the through hole of the precast beam 42. Then, the nut 31 is screwed into the projecting all screw bolts 22 through the support plate 30. Note that in FIG.
Although the diameter of the nut 31 is substantially the same as the diameter of the through hole, a nut 31 having a smaller diameter than the through hole is used, and the bearing plate 30 having a grout injection hole is used. Next, from the grout injection hole of the support plate 30,
The grout material 43 is injected into the through hole between the precast column 40 and the precast beam 42, and after the grout material 43 has hardened, the hollow nut 27 is removed with a torque wrench or the like. Since a stress acts, a compressive stress can be introduced into the concrete member by the stress. In FIG. 5, grout material is appropriately injected into joints 41 of the precast pillars 40 and 42. In FIG. 5, the prestress introduction unit 20
In order to explain the arrangement method described above, a simple diagram is used, but this is shown in more detail in FIGS. 6 (a) and 6 (b).
Further, as shown in FIG. 7, the prestress introducing unit 20 of the present invention can be used for connecting the precast beams 50a and 50b arranged to face each other with the joint 51 therebetween. As described above, the prestress introduction unit 20 of the present invention can also be used when connecting the precast columns 55a and 55b whose end faces are butted via the joint 56. Note that, as shown in FIG.
When the hollow steel rod 21 is inserted into the through hole, the outer screw 21a extends to the inside of the through hole so that the grout material can be attached. If such a thread is provided, the adhesive force between the grout material injected into the sheath tube and the surface of the hollow steel rod 21 is improved. Therefore, only one supporting plate 32 for fixing the hollow steel rod 21 to the concrete member is used. Can be omitted. The prestress introduction unit of the present invention
Screw all the bolts inside one end of the cylindrical steel bar and close it.
The other end is formed in an open state, and a steel rod is inserted into the inside of the cylindrical steel rod to introduce a compressive force to the steel rod. Because it was formed to transmit to the steel rod as tensile force, at the construction site,
After the prestress introduction unit is fixed to the concrete member, compressive stress can be introduced as prestress from the cylindrical steel bar to the surrounding concrete member only by removing the tension holding means. Therefore, it is possible to reduce the weight of the device for introducing the prestress and to facilitate handling and movement. Further, in the prestress introduction unit of the present invention, since all the screw bolts are screwed into one end of the cylindrical steel rod and fixed, the diameter of the end becomes larger than the outer periphery of the cylindrical steel rod. Therefore, the inside diameter of the through hole formed in the concrete member only needs to be slightly larger than the outside diameter of the cylindrical steel bar. Therefore, it is possible to reduce the size of the through-hole which is a structural cross-sectional defect, and to improve the structural strength of the concrete member.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view for explaining a configuration of a prestress introduction unit of the present invention. FIG. 2 is a cross-sectional view for explaining a configuration of a prestress introduction unit of the present invention. FIG. 3 is a cross-sectional view when a tensile stress is introduced into a cylindrical steel rod of the prestress introduction unit of the present invention. FIG. 4 is a cross-sectional view of the prestress introduction unit after a tensile stress is introduced into the cylindrical steel bar in FIG. FIG. 5 is a cross-sectional layout view of a prestress introduction unit arranged to connect two precast members. FIG. 6 is a cross-sectional view of a prestress introduction unit provided for connecting a column and a beam. FIG. 7 is a cross-sectional view of a prestress introduction unit provided for connecting beams. FIG. 8 is a cross-sectional view of a prestress introduction unit provided for connecting columns. [Description of Signs] 20 Prestress introduction unit 21 Hollow steel bar (cylindrical steel bar) 22 Full screw bolt 24 Hollow steel bar (Steel bar) 25 Coupler (Tension holding means) 26 Intermediate member (Tension holding means) 27 Hollow Bolt (tension holding means) 21a Outer screw (screw thread) 21c Inner screw (screw thread)

Continuation of the front page (56) Reference Jikken 42-6756 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) E04G 21/12 104 E04B 1/58 503,506

Claims (1)

(57) Claims 1. A pre-stress introducing unit for introducing a compressive stress to a concrete member, wherein a thread is formed on an inner periphery of a first end , and a second end is formed. Screw thread on the outer circumference of the part
A formed cylindrical steel rod and a first end inner periphery of the cylindrical steel rod
And a steel rod inserted into the cylindrical steel rod to introduce a compressive force, and the compressive force introduced into the steel rod is retained, and the compressive force is reduced by the above-described method. Detachable tension holding means for transmitting a tensile force to the cylindrical steel rod ;
The tension holding means cooperates with the formation of a screw thread on the inner circumference at one end.
The other end of which is screwed around the outer periphery of the second end of the cylindrical steel rod
-Shaped coupler and a front end fitted in the cylindrical coupler
It is provided movably so that it can contact the end of the steel rod
An intervening member, and the cylindrical cut so as to contact the intervening member.
The hollow bolt screwed into the screw thread on the inner circumference of the end of the puller
A prestress introduction unit characterized by comprising: