CN102587689B - Repairing and strengthening method for existing reinforced concrete beam-column joints - Google Patents

Abstract

The invention discloses a method for repairing and strengthening the existing reinforced concrete beam-column joints. By building an operation platform around the repaired concrete frame column and by rationally arranging the construction of the steel pipe frame of the operation platform, the operation platform can be scientifically and effectively Decompose the force load of the concrete frame column joints, support the beam above the concrete frame column through the jacking frame, and lift and reset the bottom of the beam beam through the underpinning jack. When the beam is jacked up to the lifting height, the deformation at the top of the concrete frame column top is stretched and reset in the opposite direction to eliminate the deformation at the top of the frame concrete. The dog holes at the joints of concrete frame columns and beams are repaired layer by layer. Finally, the cracks in the concrete frame beams and columns are repaired with carbon fiber reinforcement until all defects in the entire concrete frame beams and columns are repaired.

Description

A repair and reinforcement method for existing reinforced concrete beam-column joints

technical field

The invention belongs to the field of reinforcing and transforming existing buildings in civil engineering, and in particular relates to a method for repairing and reinforcing existing reinforced concrete beam-column joints.

Background technique

The traditional repair methods of beams and columns of reinforced concrete structures mainly include: outsourcing steel, sealing with epoxy glue, pasting carbon fiber cloth and other methods. The outsourcing steel method is mainly used in the case of relatively light damage to the concrete column, that is, the concrete column does not appear to be deformed, and the outsourcing steel method mainly repairs the damage of the corners of the beam and column, and is not suitable for the situation where the concrete beam-column joints are damaged. It is not possible to restore the deformation and position of the concrete beam-column joints; the epoxy glue sealing method is mainly suitable for the situation where the fire protection level is high, and the weight of the epoxy glue is easy to cause secondary damage to the repaired concrete columns. Repair the deformation of concrete beams and columns; the method of pasting carbon fiber cloth is suitable for ordinary small load structures or components, and the use of pasting carbon fiber cloth cannot greatly improve the overall strength of structures or components.

In summary, it can be seen that when there is a large dog hole at the connection between the top of the reinforced concrete column and the frame beam, there is deformation and displacement at the top of the concrete column, and there are many cracks in the beams and columns, the above methods cannot be completely corrected. fixed.

Contents of the invention

In view of the defects or deficiencies in the prior art, the purpose of the present invention is to ensure that the existing concrete frame beams and columns are not removed and other components are not damaged, and the concrete frame column tops and frame beams are connected at the pouring beam How to repair and strengthen the frame concrete beam-column joints of existing buildings when there are large dog holes formed at the bottom of the beam during concrete, deformation at the top of the frame concrete column, and cracks in many places on the beam and column.

In order to realize above-mentioned technical task, the present invention adopts following technical scheme to realize:

A method for repairing and reinforcing existing reinforced concrete frame beam-column joints, the method comprising the following steps:

(1) Build the work platform: build the work platform around the concrete frame column of the existing building, and at 2/3 of the height of the concrete frame column. Two layers of channel steel are laid under the work platform, and a cross-shaped dense reinforcement area is set around the central part of the work platform. The vertical and horizontal spacing of steel pipe frame poles in the reinforcement area is 800mm;

(2) Beam end support: Use jacking brackets to support the four beam ends of the crossbeam vertically crossing the concrete frame column on the working platform along the surrounding of the concrete frame column;

(3) Unloading: unloading the load supported by the concrete column;

(4) Bottom jacking and reset of concrete frame beams: Set two underpinning jacks on both sides below the jacking support at each concrete frame beam end, and use the jacks to jack up the four beam ends of the vertical cross beams above the concrete frame columns at a uniform speed, When the lifting height of the bottom end of the vertically intersecting beam above the concrete frame column reaches the original design requirement height + 3mm, stop the jack to lift the four beam ends, and then replace the jack with a steel pad;

(5) Deformation reset of concrete frame column: use the guide chain to stretch along the opposite direction of the concrete frame column top deformation at the top of the concrete frame column until the lateral deformation of the concrete frame column top is eliminated;

(6) Clean up the dog hole: remove the crispy concrete at the joint between the top of the concrete frame column and the concrete frame beam until the new hard surface of the structure is exposed;

(7) Concrete frame column repair: Use high-strength composite grouting material to repair the dog hole on the top of the concrete frame column layer by layer. In wet state, curing concrete frame column for 2-3d;

(8) Reinforcing by pasting carbon fiber cloth: Paste carbon fiber cloth on ^cracks of concrete frame beams and concrete frame columns. 500mm wide carbon fiber hoops are used for reinforcement at the stress concentration of column joints, and carbon fiber hoops with a diameter of 100mm and a spacing of 200mm are used for reinforcement for the horizontal cracks in the middle of the concrete frame column;

(9) Removal of the operating platform and jacking brackets: After curing the carbon fiber reinforced concrete frame beams and concrete frame columns for 7 days, remove the operating platforms and jacking brackets.

The present invention also has the following technical characteristics:

Step (7) The water-cement ratio of the high-strength composite grout and the fast-setting rapid-hardening cement-based grout used in the repairing process of the concrete frame column does not exceed 0.4, and the strength reaches C45.

Compared with the prior art, the present invention repairs the nodes without changing or damaging the self-strength of the node components, and then restores and repairs the existing concrete frame columns and beams. The strength of the existing concrete frame column reinforced by the present invention is increased by 5MPa compared with the actual design strength value to meet the strength requirement; the axis of the repaired beam and column meets the design requirement.

Description of drawings

Fig. 1 is a schematic diagram of the lifting system when the beam is supported and the bottom of the beam is lifted and reset in the present invention.

Fig. 2 is a schematic diagram of the carbon fiber reinforcing operation of the present invention.

Fig. 3 is a schematic diagram of the arrangement of the steel frame tubes of the concrete frame column work platform of the present invention, wherein Fig. 3a is a schematic plan view of the arrangement of the concrete frame column steel tube frames, and Fig. 3b is a schematic diagram of the overall layout of the steel frame tubes of the concrete frame column work platform.

The specific content of the present invention will be described in further detail below in conjunction with the accompanying drawings.

Detailed ways

In the present invention, by building an operation platform around the repaired concrete frame column, and by rationally arranging the construction of the steel pipe frame of the operation platform, the operation platform can scientifically and effectively decompose the force load of the concrete frame column nodes, and the concrete frame is lifted by the jacking frame. The beam above the column is supported, and the bottom of the beam is lifted and reset by the underpinning jack. When the beam is jacked up to the lifting height, the deformation at the top of the concrete frame column top is stretched and reset in the opposite direction to eliminate the deformation at the top of the frame concrete. The dog holes at the joints of concrete frame columns and beams are repaired layer by layer. Finally, the cracks in the concrete frame beams and columns are repaired with carbon fiber reinforcement until all defects in the entire concrete frame beams and columns are repaired.

Example:

The following is one of the examples given by the inventor. An existing building in Baoji City has a concrete frame column section size of 600*600mm, a concrete column height of 9000mm, and a concrete column strength of C40. The steel bars are too dense, and a large test dog hole is formed during the pouring of concrete. After the load is applied to the upper part of the concrete column, the node area is damaged, and the column top is offset to the east by about 60mm from the axis, and appears within the column height of the concrete column. There are many horizontal cracks, the crack width is about 0.2-0.3mm, and cracks of different degrees also appear in the lower part of the beam.

For the existing problems of the above-mentioned existing buildings, follow the technical scheme of the present invention, and follow the steps below to repair and reinforce the concrete frame beams and column nodes of the existing buildings,

Step 1: Build the operation platform: build the operation platform around the existing concrete frame column and at 2/3 of the height of the concrete frame column. The vertical and horizontal distances are 400/800mm, and horizontal 20# channel steel and vertical 20# two-layer channel steel are laid sequentially under the work platform. The rigidity and stability of the platform must ensure that the load is evenly distributed and transmitted downward during jacking operations on the working platform.

Referring to Fig. 3, the schematic diagram of the layout of the steel pipe frame of the concrete frame column operation platform of the present invention, wherein in the densely reinforced area in Fig. The spacing is 800mm. The shear braces are arranged according to the form of the facade, and the scissor braces can be set on the inside where the ladder is met.

In order to make it easier for construction workers to go up and down, a climbing ladder is set up in the non-intensive reinforcement area. See Figure 3b, the width of the climbing ladder is 600mm. The connection of the steel pipe frame is a steel fastener, and the tightening torque should not be less than 40N.M, nor greater than 65N.M.

Step 2: Beam end support: Use jacking brackets along the periphery of the concrete frame column on the working platform to support the four beam ends of the vertically crossing beams above the concrete frame column.

Step 3: Unloading: Unloading the load supported by the concrete frame beams and columns.

Step 4: Lift and reset the bottom of the frame beam: Set up two underpinning jacks on both sides below the jacking support at each beam end, and use the jack to lift the four beam ends of the vertical cross beam above the concrete frame column at a uniform speed, and the concrete frame When the lifting height of the bottom end of the vertically intersecting beam above the column reaches the required height +3mm, stop the jack to raise the four beam ends, and then replace the jack with a steel pad.

Referring to Fig. 1, 4 sets of 32t hydraulic jacks are used at the fulcrum of the frame beam of the present invention, and a No. 14 I-beam is also installed on the top of the jack. The support points are fastened.

Step 5, reset the deformation of the concrete frame column: use a 3-ton guide chain on the top of the concrete frame column to stretch in the opposite direction of the deformation of the top of the concrete frame column, that is, to the west, until the top of the concrete frame column eliminates the lateral deformation and deformation .

Step 6: Clean up the dog hole: remove the unqualified concrete at the joints of concrete beams and columns until the new surface of the concrete structure is exposed, and clean the surface of the concrete frame column.

Step 7: Concrete frame column joint repair: use GM2102 high-strength composite grouting material to pour the dog hole on the top of the concrete frame column layer by layer, and use GRCM fast-setting rapid-hardening cement-based grouting material to plug the hole when repairing the dog hole At the entrance of the dog hole, keep the grouting material in a wet state, and water the concrete frame column for 2-3 days.

The water-cement ratio of the above-mentioned high-strength composite grout and fast-setting rapid-hardening cement-based grout does not exceed 0.4, and the strength reaches C45.

Step 8: Paste carbon fiber cloth reinforcement: Paste carbon fiber cloth on cracks of concrete frame beams and columns. Among them, the specification of carbon fiber cloth is 300g/m ² , and it is pasted with epoxy resin glue. At the joints of concrete frame beams and columns, 500mm wide carbon fiber hoops are used for reinforcement. For the horizontal cracks in the middle of concrete frame columns, use Carbon fiber hoops with a diameter of 100mm and a pitch of 200mm are closed.

Step 9: Remove the operation platform and jacking bracket: After curing the carbon fiber reinforced concrete frame column for 7 days, remove all the operating platform and jacking bracket.

Following the above technical steps of the present invention, the concrete strength of the original concrete beam-column joint reaches C45, which is one level higher than the strength of the original beam and column concrete, and the center line of the concrete column deviates from the original design axis by 1.5 mm, meeting the requirements of design and construction acceptance specifications, The position of the beam is consistent with the original design position, and there is no secondary damage to the beam and column joints.

Claims (2)

1. A kind of repairing and strengthening method of existing reinforced concrete beam-column joint, it is characterized in that: the method may further comprise the steps: (1) Build the work platform: build the work platform around the concrete frame column of the existing building, and at 2/3 of the height of the concrete frame column. Two layers of channel steel are laid under the work platform, and a cross-shaped dense reinforcement area is set around the central part of the work platform. The vertical and horizontal spacing of steel pipe frame poles in the reinforcement area is 800mm; (2) Beam end support: Use jacking brackets to support the four beam ends of the crossbeam vertically crossing the concrete frame column on the working platform along the surrounding of the concrete frame column; (3) Unloading: unloading the load supported by the concrete column; (4) Bottom jacking and reset of concrete frame beams: Set two underpinning jacks on both sides below the jacking support at each concrete frame beam end, and use the jacks to jack up the four beam ends of the vertical cross beams above the concrete frame columns at a uniform speed, When the lifting height of the bottom end of the vertically intersecting beam above the concrete frame column reaches the original design requirement height + 3mm, stop the jack to lift the four beam ends, and then replace the jack with a steel pad; (5) Deformation reset of concrete frame column: use the guide chain to stretch along the opposite direction of the concrete frame column top deformation at the top of the concrete frame column until the lateral deformation of the concrete frame column top is eliminated; (6) Clean up the dog hole: remove the crispy concrete at the joint between the top of the concrete frame column and the concrete frame beam until the new hard surface of the structure is exposed; (7) Concrete frame column repair: Use high-strength composite grouting material to repair the dog hole on the top of the concrete frame column layer by layer. In wet state, curing concrete frame column for 2-3d; (8) Reinforcing by pasting carbon fiber cloth: Paste carbon fiber cloth on ^cracks of concrete frame beams and concrete frame columns. 500mm wide carbon fiber hoops are used for reinforcement at the stress concentration of column joints, and carbon fiber hoops with a diameter of 100mm and a spacing of 200mm are used for reinforcement for the horizontal cracks in the middle of the concrete frame column; (9) Removal of the operating platform and jacking brackets: After curing the carbon fiber reinforced concrete frame beams and concrete frame columns for 7 days, remove the operating platforms and jacking brackets. 2. the repairing and reinforcement method of existing reinforced concrete beam-column joint as claimed in claim 1, is characterized in that: the high-strength type composite grouting material and fast-setting rapid-hardening type cement adopted in step (7) concrete frame column repairing process The water-cement ratio of the base grouting material shall not exceed 0.4, and the strength shall reach C45.