CN105952179A - Bonding prestress reinforced concrete girder reinforced through pre-tensioning method and reinforcing method - Google Patents

Abstract

Reinforced concrete beams with bonded prestress and reinforcement methods using pretensioning method can solve the overload problem of the original structural beam steel bars in the built buildings due to the secondary stress, strengthen the collaborative work ability of the reinforced components and the original structural beams, and improve the original structural beams The bearing capacity of the beam can be improved to improve the reinforcement effect of the original structural beam, which includes reinforcement angle steel 1, implanted steel bar 2, connecting angle steel II 3, lock nut 4, steel sheet 5, U-shaped stirrup 6, lock nut 7 and steel pad plate 8; there are two reinforced angle steels 1, which are pasted on the two bottom corners of the beam 9 respectively; four connecting angle steels 3 are used to connect the reinforced angle steel 1 and the columns 10 on both sides of the beam 9; the reinforced angle steel 1 and the connecting The angle steel 3 is connected by welding; the steel sheet 5 and the connecting angle steel 3 are connected by welding; the connecting angle steel 3 and the column 10 are connected by implanting the steel bar 2 and the lock nut 4; the U-shaped stirrup 6 passes upwards For the floor 11 , use lock nuts 7 to fix both ends of the U-shaped stirrup 6 on the steel backing plate 8 ; the steel backing plate 8 is located above the floor 11 .

Description

Strengthening Reinforced Concrete Beams with Bonded Prestress by Pretensioning Method and Its Strengthening Method

technical field

The invention belongs to the technical field of reinforcement of built buildings and is used for the reinforcement project of middle beams of built reinforced concrete buildings.

Background technique

Nowadays, while new houses are increasing, more and more attention is paid to the maintenance, repair and reinforcement of new and old buildings. This not only saves a lot of money, but also conforms to the strategic goal of sustainable development of civil engineering construction in the new century. In addition, in a large number of reinforced concrete structure projects, due to design errors, construction quality, and changes in the use and function of the house, the strength and stiffness of the beams in the reinforced concrete structure frame are insufficient, which affects the normal use of the structure. How to effectively reinforce and strengthen reinforced concrete members to ensure their safe use has been a subject of extensive research by domestic and foreign civil engineering experts in recent years. Our country has done a lot of research and practical work on the reinforcement and reinforcement of reinforced concrete members, and has gained rich experience.

At present, the commonly used reinforcement methods mainly include enlarging section reinforcement method, outsourcing steel method, bonded steel reinforcement method and carbon fiber reinforcement method, etc. For the reinforcement of reinforced concrete beams, the bonded steel reinforcement method and carbon fiber reinforcement method are more commonly used nowadays. Although these methods are effective, because the stressed steel bars in some beam members may have reached a higher stress state during reinforcement, It has even exceeded the yield strength of the steel bar. The stress and deformation of the steel bar in the original beam are too large. Lost the meaning of reinforcement.

With the continuous development of engineering technology, external prestressed reinforcement method and prestressed steel and concrete composite structure reinforced beam method have appeared now. Although these methods can overcome the shortcomings of the above two methods, they still have the following problems: ①The ability of the reinforced steel to cooperate with the original structure is poor; ②The size of the reinforced components is too large and requires a large space, which reduces the height of the building space and is inconvenient for decoration. Therefore, there is an urgent need for a strengthening method that can strengthen the synchronous working ability of the reinforced member and the original beam, and can solve the overload problem of the secondary force of the original beam reinforcement.

Contents of the invention

The purpose of the present invention is to solve the overload problem of the original structural beam steel bar in the built building due to the secondary stress, to strengthen the collaborative work ability of the reinforced member and the original structural beam, to improve the bearing capacity of the original structural beam, and to improve the reinforcement effect of the original structural beam .

The present invention adopts the pretensioning method to strengthen the reinforced concrete beam with bonded prestress and the reinforcement method. The pretensioned method is adopted to strengthen the reinforced concrete beam with bonded prestress. Nut 4, steel sheet 5, U-shaped stirrup 6, second locking nut 7 and steel backing plate 8 are formed, and described reinforcing angle steel 1 is two, sticks on two bottom corners of beam 9 respectively; Described connecting angle steel 3 is four, used to connect the two ends of the reinforced angle steel 1 with the columns 10 on both sides of the beam 9, the reinforced angle steel 1 is connected with the connecting angle steel 3; the steel sheet 5 is connected with the connecting angle steel 3; the implanted The steel bar 2 is used to connect the connecting angle steel 3 and the column 10, and the quantity of the implanted steel bar 2 is determined by the area of the connecting angle steel 3; the first locking nut 4 is used to lock and fix the implanted steel bar 2; The U-shaped stirrup 6 is close to the two bottom corners of the beam 9 and passes through the floor 11 upwards, and is fixed on the steel backing plate 8 by the second locking nut 7; the steel backing plate 8 is placed on the floor 11 in advance.

The strengthening method of reinforced concrete beams with bonded prestress is as follows:

(1) Carry out reinforcement calculations on the original reinforced concrete beams to obtain the cross-sectional area of the required reinforcement, and select an angle steel with a suitable cross-sectional area as the reinforcement angle steel 1 according to the calculation results. The reinforcement angle steel 1 is one grade higher than the original beam reinforcement;

(2) The connecting angle steel 3 needs to be cold-formed and cut in advance, and its strength level is higher than that of the reinforced angle steel 1, and its length is determined according to the size of the beam 9 and column 10, so as to ensure that the connecting angle steel 3 does not exceed the height of the beam 9 or column 10 boundary;

(3) In order to increase the contact area between the connecting angle steel 3 and the column 10 and enhance the connection effect, a steel sheet 5 is welded at the cut-off point of the connecting angle steel 3, and the size, thickness and strength of the steel sheet 5 should be consistent with the connecting angle steel 3;

(4) The implanted length l of the implanted steel bar 2 is based on the test of the concrete test block with the same strength as the original beam concrete and Determined, l is the length of the implanted steel bar 2, d is the diameter of the implanted steel bar 2, f _y is the strength design value of the implanted steel bar 2, A _s is the cross-sectional area of the implanted steel bar 2, f _t is the concrete at the implanted place Tensile strength design value, safety improvement factor 1.2; implanted steel bar 2 is one strength grade higher than the original beam steel bar, and the number of implanted steel bars 2 in each place is 6-8, and each implanted steel bar 2 is pre-installed Process the thread with a length of about 50mm at the exposed end;

(5) Pre-process threads with a length of about 50mm at both ends of the U-shaped stirrup 6, and the U-shaped stirrup 6 needs to be higher than the original beam stirrup;

(6) Place the two reinforced angle steels 1 on the two bottom corners of the beam 9;

(7) The U-shaped stirrups 5 are arranged at equal intervals, pass upward through the floor 11, and are fixed on the steel backing plate 8 with the second lock nut 7; the U-shaped stirrups 6 can temporarily fix the reinforced angle steel 1 ;

(8) Drill a hole at the corresponding position of the column 10, place and anchor the implanted steel bar 2, the implanted steel bar 2 passes through the connecting angle steel 3, and fix it on the connecting angle steel 3 with the first lock nut 4 by welding Connect the reinforcement angle steel 1 and the connection angle steel 3;

(9) Use the first lock nut 4 to tension the reinforced angle steel 1, and stretch it until its control stress stops; use the second lock nut 7 to tension the U-shaped stirrup 6, and tension it to its control stress stop;

(10) After the tension is over, apply high-strength construction adhesive to the gap between the reinforced angle steel 1 and the beam 9 to bond the two; after the construction adhesive reaches its strength value, loosen the first lock nut 4, and Reinforce the angle steel 1 for unloading;

(11) Apply the protective layer 12 on the floor 11.

The beneficial effects of the present invention are:

1. The prestress applied to the reinforced angle steel 1 by implanting steel bars 2, the bonding force between the reinforced angle steel 1 and the beam 9, and the precompressive stress applied to the reinforced angle steel 1 by the U-shaped stirrup 6 are to reinforce the angle steel 1 and the beam 9 The close combination provides triple protection;

2. Tighten and then loosen the first lock nut 4, which can prevent the prestress generated on the beam 9 from being borne by the column 10 all the time, and reduce the load on the column 10;

3. The prestress applied to the reinforced angle steel 1 by the implanted steel bar 2 can not only unload the steel bar of the original structural beam, but also bear the load transmitted by the upper structure together with the original steel bar, improving the original structural beam steel bar and The collaborative work ability of reinforced angle steel 1; when the beam bears a large load, the synchronous work of the original beam steel bar and the reinforced angle steel 1 is realized, preventing the original beam steel bar from reaching the ultimate damage state before the reinforced angle steel 1, thereby solving the problem of the original beam steel bar The overload problem that may occur in the secondary force;

4. The U-shaped stirrup 6 passes through the floor 11 and is fixed on the steel backing plate 8, which can reinforce the full height of the oblique section of the beam 9, which not only increases the shear resistance of the beam 9, but also restores the deformation cracks generated by the beam 9 ;

5. The U-shaped stirrup 6 passes through the floor 11 and is fixed on the floor 11 with the second locking nut 7, which is more convenient for construction, and is also convenient for decoration and covering after construction, reducing the impact on the use environment.

Description of drawings

Figure 1 is a schematic diagram of the reinforced connection between a concrete beam and a column, Figure 2 is a schematic diagram of a section 1-1 of a reinforced connection between a concrete beam and a column, Figure 3 is a schematic diagram of a concrete beam reinforced by U-shaped stirrups 6, and Figure 4 is a schematic diagram of a reinforced concrete beam reinforced by U-shaped stirrups 6 2-2 Sectional schematic diagram.

detailed description

The present invention adopts the pretensioning method to strengthen the reinforced concrete beam with bonded prestress and the reinforcement method. The pretensioned method is adopted to strengthen the reinforced concrete beam with bonded prestress. Nut 4, steel sheet 5, U-shaped stirrup 6, second locking nut 7 and steel backing plate 8 are formed, and described reinforcing angle steel 1 is two, sticks on two bottom corners of beam 9 respectively; Described connecting angle steel 3 is four, used to connect the two ends of the reinforced angle steel 1 with the columns 10 on both sides of the beam 9 respectively, the reinforced angle steel 1 and the connecting angle steel 3 are connected by welding; the steel sheet 5 and the connecting angle steel 3 are connected by The connection is carried out by welding; the implanted steel bar 2 is used to connect the connecting angle steel 3 and the column 10, and the quantity of the implanted steel bar 2 is determined by the area of the connecting angle steel 3; the first lock nut 4 is used to connect the The steel bar 2 is locked and fixed; the U-shaped stirrup 6 is close to the two bottom corners of the beam 9 and passes through the floor 11 upwards, and is fixed on the steel backing plate 8 by the second locking nut 7; the steel backing The panels 8 are placed on the floor 11 in advance.

The strengthening method of reinforced concrete beams with bonded prestress is as follows:

(1) Carry out reinforcement calculations on the original reinforced concrete beams to obtain the cross-sectional area of the required reinforcement, and select an angle steel with a suitable cross-sectional area as the reinforcement angle steel 1 according to the calculation results. The reinforcement angle steel 1 is one grade higher than the original beam reinforcement;

(2) The connecting angle steel 3 needs to be cold-formed and cut in advance, and its strength level is higher than that of the reinforced angle steel 1, and its length is determined according to the size of the beam 9 and column 10, so as to ensure that the connecting angle steel 3 does not exceed the height of the beam 9 or column 10 boundary;

(3) In order to increase the contact area between the connecting angle steel 3 and the column 10 and enhance the connection effect, a steel sheet 5 is welded at the cut part of the connecting angle steel 3, and the size, thickness and strength of the steel sheet 5 should be consistent with the connecting angle steel 3;

(4) The implanted length l of the implanted steel bar 2 is based on the test of the concrete test block with the same strength as the original beam concrete and Determined, l is the length of the implanted steel bar 2, d is the diameter of the implanted steel bar 2, f _y is the strength design value of the implanted steel bar 2, A _s is the cross-sectional area of the implanted steel bar 2, f _t is the concrete at the implanted place Tensile strength design value, safety improvement factor 1.2; implanted steel bar 2 is one strength grade higher than the original beam steel bar, and the number of implanted steel bars 2 in each place is 6-8, and each implanted steel bar 2 is pre-installed Process the thread with a length of about 50mm at the exposed end;

(5) Pre-process threads with a length of about 50mm at both ends of the U-shaped stirrup 6, and the U-shaped stirrup 6 needs to be higher than the original beam stirrup;

(6) Place the two reinforced angle steels 1 on the two bottom corners of the beam 9;

(7) The U-shaped stirrups 5 are arranged at equal intervals, pass upward through the floor 11, and are fixed on the steel backing plate 8 with the second lock nut 7; the U-shaped stirrups 6 can temporarily fix the reinforced angle steel 1 ;

(8) Drill a hole at the corresponding position of the column 10, place and anchor the implanted steel bar 2, the implanted steel bar 2 passes through the connecting angle steel 3, and fix it on the connecting angle steel 3 with the first lock nut 4 by welding Connect the reinforcement angle steel 1 and the connection angle steel 3;

(9) Use the first lock nut 4 to tension the reinforced angle steel 1 until its control stress stops; use the second lock nut 7 to tension the U-shaped stirrup 6 until it controls stress stop;

(10) After the tension is over, apply high-strength construction adhesive to the gap between the reinforced angle steel 1 and the beam 9 to bond the two; after the construction adhesive reaches its strength value, loosen the first lock nut 4, and Reinforce the angle steel 1 for unloading;

(11) Apply the protective layer 12 on the floor 11.

Fig. 1 is a schematic diagram of reinforced connection between concrete beam and column, Fig. 2 is a schematic diagram of section 1-1 of reinforced connection between concrete beam and column, Fig. 3 is a schematic diagram of reinforced concrete beam with U-shaped stirrup 6, Fig. 4 is a schematic diagram of reinforced concrete beam with U-shaped hoop 6 2-2 Sectional schematic diagram. As shown in the figure, the reinforced concrete beam reinforced with bonded prestress by pretensioning method includes reinforcement angle steel 1, implanted steel bar 2, connecting angle steel 3, first lock nut 4, steel sheet 5, U-shaped stirrup bar 6, second Lock nut 7, steel backing plate 8 and protective layer 12; There are two reinforcement angle steels 1, which are pasted on the two bottom corners of beam 9 respectively; There are four connection angle steels 3, which need to be processed in advance, and need to be processed according to planting conditions. The quantity and diameter of the steel bars 2 are drilled at the corresponding positions of the connecting angle steel 3 in advance; the connecting angle steel 3 is used to connect the two ends of the reinforced angle steel 1 with the columns 10 on both sides of the beam respectively; the reinforced angle steel 1 and the connecting angle steel 3 are welded The steel sheet 5 and the connecting angle steel II 3 are connected by welding; the implanted steel bar 2 is used to connect the connecting angle steel 3 and the column 10, and then the implanted steel bar 2 is locked by the first lock nut 4 The number of implanted steel bars 2 is determined by the area of the connecting angle steel 3; the U-shaped stirrup 6 wraps the two bottom corners of the beam 9 and passes through the floor 11 upwards, and is fixed on the steel backing plate by the second lock nut 7 8; the steel backing plate 8 is placed on the floor 11 in advance.

The reinforcement method of reinforced concrete beams with bonded prestress is adopted, and the specific implementation steps are as follows:

1. Carry out reinforcement calculations on the original reinforced concrete beams to obtain the cross-sectional area of the required reinforcement. According to the calculation results, select an angle steel with a suitable cross-sectional area as the reinforced angle steel 1. The reinforced angle steel 1 should be one strength level higher than the original beam reinforcement.

2. The connection angle steel 3 needs to be cold-formed and cut in advance, and its specification must be higher than that of the reinforced angle steel 1. According to the number of implanted steel bars 2, holes are drilled in the corresponding position of each connection angle steel 3 in advance to connect the angle steel 3. The length can be determined according to the size of the beam 9 and the column 10, so as to ensure that the connecting angle steel 3 does not exceed the boundary of the beam 9 or the column 10.

3. In order to increase the contact area between the connecting angle steel 3 and the column 10 and enhance the connection effect, a steel sheet 5 is welded at the cut-out of the connecting angle steel 3. The size, thickness and strength of the steel sheet 5 should be consistent with the connecting angle steel 3.

4. According to the corresponding calculation method or the test of the concrete test block with the same strength as the original beam concrete, determine the implantation length of the implanted steel bar 2, so as to determine its total length. The implanted steel bar 2 should be higher than the original beam steel bar by one strength level , the quantity of each implanted steel bar 2 can be determined according to the area of the connecting angle steel 3, generally 6-8 are advisable, and a thread about 50 mm long is processed at the exposed end of each implanted steel bar 2 in advance.

5. Process threads about 50 mm long at both ends of the U-shaped stirrup 6 in advance, and the U-shaped stirrup 6 needs to be higher in strength than the original beam stirrup.

6. Place the two reinforced angle steels I1 on the two bottom corners of the beam 9.

7. The U-shaped stirrups 6 are arranged at equal intervals, pass through the floor 11 upwards, and are fixed on the steel backing plate 8 with the second lock nut 7; the U-shaped stirrups 6 can temporarily fix the reinforced angle steel 1.

8. Drill a hole at the corresponding position of the column 10, place and anchor the implanted steel bar 2, the implanted steel bar 2 passes through the connecting angle steel 3, and fix it on the connecting angle steel 3 with the first lock nut 4, and weld it Reinforcement angle steel 1 and connection angle steel 3 are connected.

9. Use the first lock nut 4 to tension the reinforced angle steel 1 until its control stress stops; use the second lock nut 7 to tension the U-shaped stirrup 6 until it reaches its control stress stop.

10. After the tensioning is over, apply high-strength construction adhesive to the gap between the reinforced angle steel 1 and the beam 9 to bond the two; after the construction adhesive reaches its strength value, loosen the first lock nut 4 to fix the reinforcement Angle 1 is unloaded.

In this embodiment, the protective layer 12 is cast on the floor 11 by casting in place, and the top of the U-shaped stirrup 6 , the second lock nut 7 and the steel backing plate 8 are cast in the protective layer 12 . The protection layer 12 not only prevents the corrosion of the U-shaped stirrup 6, the second lock nut 7 and the steel backing plate 8, but also beautifies the environment of the building and enhances the bearing capacity of the floor 11.

Claims (2)

1. use pre-tensioning system to have and cohere prestressed reinforcement reinforced beam, by reinforcing angle (1), implant reinforcing bar (2), joint angle Steel (3), the first locking nut (4), steel disc (5), U-shaped stirrup (6), the second locking nut (7) and billet (8) are constituted, and it is special Levy and be: described reinforcing angle (1) is two, be respectively adhered on two base angles of beam (9)；Described angle cleat (3) is four, In order to by the two ends of reinforcing angle (1) respectively pillar (10) with beam (9) both sides couple together, reinforcing angle (1) and joint angle Steel (3) connects；Described steel disc (5) and angle cleat (3) connect；Described implantation reinforcing bar (2) is used for angle cleat (3) and pillar (10) being attached, the quantity implanting reinforcing bar (2) is determined by the area of angle cleat (3)；Described first locking nut (4) is used for Reinforcing bar (2) will be implanted be locked；Described U-shaped stirrup (6) is close to two base angles of beam (9) and is upward through floor (11), the second locking nut (7) it is fixed on billet (8)；Described billet (8) is previously placed on floor (11).

2. use and have the reinforcement means cohering prestressed reinforcement reinforced beam, it is characterised in that the steps include:

(1) raw steel Concrete Beam Reinforced is carried out reinforcement calculating, draw the sectional area that required reinforcement is firm, select to cut according to result of calculation The suitable angle steel of area as reinforcing angle (1), reinforcing angle (1) strength grade higher than former beam steel；

(2) angle cleat (3) needs to first pass through clod wash and cutting process in advance, and its strength grade is more than the intensity of reinforcing angle (1) Grade, its length determines according to the size of beam (9) and pillar (10), it is ensured that angle cleat (3) is without departing from beam (9) or pillar (10) Border；

(3) for increasing the contact area of angle cleat (3) and pillar (10), strengthen and connect effect, cut at angle cleat (3) Place, welds a steel disc (5), and size, thickness and the intensity of steel disc (5) should be consistent with angle cleat (3)；

(4) the implantation length of reinforcing bar (2) is implantedlAccording to the concrete test block test strong with former beam concrete etc. and Determine,lFor implanting the length of reinforcing bar (2),dFor implanting the diameter of reinforcing bar (2),f _y For implanting the strength failure criterion of reinforcing bar (2),A _s For implanting the sectional area of reinforcing bar (2),f _t For concrete tensile strength design load at implantation, degree of safety improves coefficient 1.2；Implant steel Muscle (2) strength grade higher than former beam steel, it is 6-8 that the quantity of reinforcing bar (2) is implanted in everywhere, and in advance often take root in into The bared end processing of reinforcing bar (2) is about the screw thread of 50mm；

(5) be about the screw thread of 50mm in advance in the processing of the two ends of U-shaped stirrup (6), U-shaped stirrup (6) need to be higher than former beam stirrup one Strength grade；

(6) two reinforcing angles (1) are placed in two base angles of beam (9)；

(7) U-shaped stirrup (5) is equally spaced, and is upward through floor (11), and is fixed in steel with the second locking nut (7) On backing plate (8)；Reinforcing angle (1) can be played interim fixation by U-shaped stirrup (6)；

(8) hole in pillar (10) relevant position, place and anchor implantation reinforcing bar (2), implant reinforcing bar (2) through joint angle Steel (3), and be fixed on angle cleat (3) with the first locking nut (4), use the mode of welding by reinforcing angle (1) It is attached with angle cleat (3)；

(9) utilize the first locking nut (4) that reinforcing angle (1) carries out stretch-draw, and be stretched to the stopping of its proof stress；Utilize Two locking nuts (7) carry out stretch-draw to U-shaped stirrup (6), and are stretched to the stopping of its proof stress；

(10), after stretch-draw terminates, in the gap of reinforcing angle (1) and beam (9), it is painted into high strength building adhesive, the two is glued Knot；After building adhesive reaches its intensity level, loosen the first locking nut (4), reinforcing angle (1) is carried out off-load；

(11) on floor (11), protective layer (12) is smeared.