Performance-based comprehensive reinforcement method for web holed reinforced concrete beam

Abstract

The invention discloses a performance-based comprehensive reinforcement method for a web holed reinforced concrete beam. A circular beam hole is formed in a concrete beam; treating the inner surface of the beam hole; the method comprises the following steps: firstly, determining the distribution position of the chemical bolt according to actual engineering, and then carrying out drilling operation in a hole according to the determined distribution position; the inner surface of the beam hole is blown clean through an air blower; firstly, the outer surface of the steel pipe is evenly coated with structural adhesive, and then the steel pipe is inserted into the beam hole; chemical bolts are installed in the through holes and penetrate into the corresponding drill holes, and then nuts of the chemical bolts are fixedly connected with the steel pipe in a welded mode; the structural adhesive is evenly smeared in the U-shaped adhesive tape and the strip-shaped adhesive, then the U-shaped carbon fiber cloth is correspondingly pasted in the U-shaped adhesive tape, and the strip-shaped carbon fiber cloth is correspondingly pasted in the strip-shaped adhesive; and coating a protective layer on the surface of the carbon fiber cloth. The method is simple in operation process, low in implementation cost, capable of achieving programmed construction of concrete beam holing reinforcement and suitable for large-area application and popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of building engineering reinforcement, and in particular is a performance-based comprehensive reinforcement method for reinforced concrete beams with web openings. Background Art

[0002] With the rapid development of my country's construction industry, people's requirements for living comfort are constantly increasing. As an important evaluation indicator, indoor headroom height affects people's intuitive perception of indoor space. For new buildings, some pipeline equipment can pass through the beams to ensure the indoor headroom, which helps to reduce the cost. According to the relevant policy requirements of my country's construction industry, the renovation method for old communities is no longer mainly demolition, but renovation. In the process of renovating old community buildings, it is bound to encounter the conditions of adding air conditioning ventilation and water, electricity, and gas pipelines. Opening holes in the beams to arrange pipelines as a convenient implementation plan can not only meet the renovation requirements, but also effectively meet the users' needs for indoor headroom.

[0003] Opening holes in beams to allow pipes of various equipment to pass smoothly has a very broad application prospect, whether for new high-rise buildings or for the renovation of old buildings. However, compared with solid beams, opening holes in beams will destroy the integrity of the beams and interrupt the continuity of the cross section, and the mechanical properties of the beams, such as the bearing capacity and cross-sectional stiffness, will be affected to varying degrees. In addition, stress concentration will occur at the openings, which will cause cracks in the components prematurely, increase the crack width and deflection of the beams to a greater or lesser extent, and even affect the normal use function of the beams. In this case, the study of the mechanical properties of beams with holes is particularly important, and the reinforcement research on the beam web after the holes are opened has also become a major research topic in the engineering field. In actual engineering, the position of the holes in the beams has a certain randomness, so it is very necessary to study the influence of the holes in different sections on the mechanical properties of the beams and the corresponding reinforcement research. Since the holes in the beams will weaken their mechanical properties and change the failure mode, it is urgent to provide an effective reinforcement measure to ensure the stability and reliability of the beam structure. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a performance-based comprehensive reinforcement method for reinforced concrete beams with web openings. The method has a simple operation process and low implementation cost, can reliably reinforce the concrete beams after the openings, and can realize the programmed construction of concrete beam hole reinforcement, which is suitable for large-scale promotion and application.

[0005] In order to achieve the above object, the present invention provides a performance-based comprehensive reinforcement method for reinforced concrete beams with web openings, comprising the following steps: Step 1: Open the beam opening; Opening a circular beam opening on a concrete beam; Step 2: Inner surface treatment of beam opening; S21: Grinding the inner surface of the beam opening; S22: For the holes and sunken areas on the inner surface caused by grinding, use repair glue to fill them; for deeper holes, use high-grade cement slurry to fill them; Step 3: Drilling holes in the hole; S31: first determine the distribution position of the chemical bolts according to the actual project, and then perform drilling operations in the hole according to the determined distribution position; S32: Use a blower to clean the inner surface of the beam opening; Step 4: Embed the steel pipe and drive in the chemical bolts; S41: Prefabricate steel pipes in the factory to match the beam opening size; S42: A through hole is opened on the steel pipe at a position corresponding to the drilled hole in the beam opening; S43: First, apply structural adhesive evenly on the outer surface of the steel pipe, and then insert the steel pipe into the beam opening. During the installation process, ensure that the positions of the through holes and the drilled holes correspond one to one. At the same time, ensure that the end of the steel pipe is flush with the end of the beam opening, and use structural adhesive to fill and reinforce the small gap between the end of the steel pipe and the end of the beam opening; S44: installing chemical bolts in each through hole and allowing the chemical bolts to penetrate into the corresponding drilled holes, and then fixing and connecting the nuts of the chemical bolts to the steel pipes by welding; Step 5: Paste the U-shaped carbon fiber cloth and the strip carbon fiber cloth; S51: two U-shaped adhesive tapes are respectively formed on the surface of the concrete beam at the left and right sides of the beam opening, wherein the U-shaped adhesive tapes are U-shaped and cover both side surfaces and the bottom surface of the concrete beam; and a strip adhesive tape extending transversely is respectively formed on the surface of the concrete beam at the upper and lower sides of the beam opening; S52: grinding the U-shaped adhesive tape and the strip adhesive tape respectively, and filling the holes and concave areas caused by grinding; S53: Blow the U-shaped adhesive tape and the strip adhesive tape clean with a blower, then apply an interface agent to the U-shaped adhesive tape and the strip adhesive tape, and dry for a set time; S54: first, evenly apply the structural adhesive to the U-shaped adhesive tape and the strip adhesive tape, then paste the U-shaped carbon fiber cloth to the U-shaped adhesive tape, and paste the strip carbon fiber cloth to the strip adhesive tape, wherein the U-shaped carbon fiber cloth covers the side and bottom of the concrete beam in a U-shape, and at the same time, the two ends of the strip carbon fiber cloth extend to the outside of the U-shaped carbon fiber cloth on both sides respectively, and the two strip carbon fiber cloths on the side cooperate with the four U-shaped carbon fiber cloths to form a closed inhibition area on the outside of the beam opening, and then, a plastic scraper is used to perform a reciprocating scraping process along the pasting direction until the surface is scraped to a flat state; S55: Apply a protective layer on the surface of the U-shaped carbon fiber cloth and the strip carbon fiber cloth.

[0006] As a preference, in step 2 S1 and in step 5 S52, a grinder is used to grind the concrete surface.

[0007] Furthermore, in order to ensure the subsequent bonding strength, in step three S32, after the inner surface is blown clean, an interface agent is applied to the inner surface of the beam opening and dried for a set time.

[0008] Furthermore, in order to improve the reinforcement effect on the concrete beam and ensure the effect of suppressing crack extension, in step 5 S54, the thickness of the U-shaped carbon fiber cloth and the strip carbon fiber cloth are both greater than 0.1 mm, and the width thereof are both 50-100 mm.

[0009] Furthermore, in order to effectively suppress the extension of the crack in the left-right direction, in step 5 S54, the distance between the two U-shaped carbon fiber cloths on the same side is 50-200 mm.

[0010] Furthermore, in order to ensure the firmness of the adhesion between the U-shaped carbon fiber cloth and the concrete beam, in step five S52, when grinding the U-shaped adhesive tape, if the corner of the concrete beam is a right angle, the right angle is ground into a rounded corner.

[0011] Furthermore, in order to effectively transfer the shear force and thereby effectively restore the loss of shear bearing capacity of the concrete beam caused by the opening, in step 4 S41, the thickness of the steel pipe is greater than 2 mm.

[0012] Furthermore, in order to improve the reinforcement effect, in step 4 S44, the chemical bolt is in an inverted cone shape.

[0013] In the present invention, the drilled beam opening is first polished, and then the inner surface of the beam opening is cleaned by using a blower, which can ensure that the steel pipe inserted later can be firmly and reliably connected to the inside of the beam opening through structural adhesive. The steel pipe is inserted into the inside of the beam opening, and the outer surface of the steel pipe main section and the inner surface of the beam opening main section are connected by structural adhesive, and then the small gap between the end of the steel pipe and the end of the beam opening is filled and reinforced by structural adhesive, which can effectively improve the bonding strength between the steel pipe and the beam opening, and then reliably combine the steel pipe and the concrete beam into a whole, so as to significantly improve the ability of the steel pipe and the concrete beam to transmit shear force. The added steel pipe can effectively transmit shear force, and can reduce the stress concentration effect at the corner of the beam opening, thereby effectively restoring the loss of shear bearing capacity of the concrete beam caused by the opening. On this basis, the steel pipe is anchored inside the concrete beam by chemical bolts, and the nut of the chemical bolt is welded on the steel pipe. In this way, not only the bonding strength between the steel pipe and the concrete beam and the ability to transmit shear force between the steel pipe and the concrete beam are further improved, but also the overall seismic strength after bonding can be improved, which can ensure that the steel pipe can be firmly connected to the inside of the beam opening by chemical bolts in turn under vibration. Two U-shaped carbon fiber cloths are connected on the left and right sides of the beam opening, and at the same time, a strip of carbon fiber cloth is connected on the upper and lower sides of the beam opening. On the one hand, the two strips of carbon fiber cloths on the same side and the four U-shaped carbon fiber cloths can be used to form a closed inhibition area on the outside of the end of the beam opening, so as to effectively inhibit the cracks on the concrete beam after the opening from extending outward from the end of the opening. On the other hand, the U-shaped carbon fiber cloth can be used to cover the side and bottom of the concrete beam at the same time, so as to effectively inhibit the cracks on the concrete beam after the opening from extending outward from the main area of ​​the opening. Applying a protective layer on the surface of the carbon fiber cloth can play a further reinforcement role and effectively prevent the occurrence of cracks.

[0014] Through a large number of experiments and practices, the present invention can improve the ultimate bearing capacity of the concrete beam after the hole is opened by about 10%. At the same time, it can effectively prevent the extension of cracks on the concrete beam after the hole is opened, ensuring the shear resistance and bearing strength of the concrete beam after the hole is opened. The method has a simple operation process and low implementation cost, can reliably reinforce the concrete beam after the hole is opened, and can realize the programmed construction of the concrete beam hole reinforcement, which is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 yes Figure 1 A top view of Figure 3 yes Figure 1 AA section view.

[0016] In the figure: 1. Beam opening, 2. Steel pipe, 3. U-shaped carbon fiber cloth, 4. Chemical bolts, 5. Strip carbon fiber cloth, 6. Concrete beam. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] like Figures 1 to 3 As shown, the present invention provides a performance-based comprehensive reinforcement method for reinforced concrete beams with web openings, comprising the following steps: Step 1: Open the beam opening 1; A circular beam opening 1 is provided on the concrete beam 6, and the beam opening 1 is preferably circular; The shape, position, size and eccentricity of the opening must comply with the requirements of relevant specifications such as the "Concrete Structure Construction Manual" and the "Concrete Structure Design Code".

[0019] Step 2: Inner surface treatment of beam opening 1; S21: grinding the inner surface of the beam opening 1; S22: For the holes and sunken areas on the inner surface caused by grinding, use repair glue to fill them; for deeper holes, use high-grade cement slurry to fill them; Step 3: Drilling holes in the hole; S31: firstly determine the distribution position of the chemical bolts 4 according to the actual project, and then perform drilling operations in the hole according to the determined distribution position; S32: Blow clean the inner surface of the beam opening 1 with a blower; Step 4: embed the steel pipe 2 and drive in the chemical bolt 4; S41: prefabricating a steel pipe 2 that matches the size of the beam opening 1 in a factory, wherein the length of the steel pipe 2 is the same as the length of the beam opening 1, and the outer diameter of the steel pipe 2 matches the inner diameter of the beam opening 1; S42: a through hole is formed on the steel pipe 2 at a position corresponding to the drilled hole in the beam opening 1; S43: first, evenly apply structural adhesive on the outer surface of the steel pipe 2, and then insert the steel pipe 2 into the beam opening 1. During the installation process, ensure that the positions of the through holes and the drilled holes correspond one to one. At the same time, ensure that the end of the steel pipe 2 is flush with the end of the beam opening 1, and use structural adhesive to fill and reinforce the small gap between the end of the steel pipe 2 and the end of the beam opening 1; S44: installing the chemical bolts 4 in each through hole and allowing the chemical bolts 4 to penetrate into the corresponding drilled holes, and then fixing and connecting the nuts of the chemical bolts 4 and the steel pipe 2 by welding; Step 5: Paste the U-shaped carbon fiber cloth 3 and the strip carbon fiber cloth 5; S51: two U-shaped adhesive tapes are respectively formed on the surface of the concrete beam 6 at the left and right sides of the beam opening 1, wherein the U-shaped adhesive tapes are U-shaped and cover both side surfaces and the bottom surface of the concrete beam 6; and one strip adhesive tape extending transversely is respectively formed on the surface of the concrete beam 6 at the upper and lower sides of the beam opening 1; S52: grinding the U-shaped adhesive tape and the strip adhesive tape respectively, and filling the holes and concave areas caused by grinding; S53: Blow the U-shaped adhesive tape and the strip adhesive tape clean with a blower, then apply an interface agent to the U-shaped adhesive tape and the strip adhesive tape, and dry for a set time; S54: first, evenly apply the structural adhesive to the U-shaped adhesive tape and the strip adhesive tape, then paste the U-shaped carbon fiber cloth 3 to the U-shaped adhesive tape, and paste the strip carbon fiber cloth 5 to the strip adhesive tape, wherein the U-shaped carbon fiber cloth 3 covers the side and bottom of the concrete beam 6 in a U-shape, and at the same time, the two ends of the strip carbon fiber cloth 5 extend to the outside of the U-shaped carbon fiber cloth 3 on both sides, and the two strip carbon fiber cloths 5 on the side cooperate with the four U-shaped carbon fiber cloths 3 to form a closed inhibition area on the outside of the beam opening 1, and then, a plastic scraper is used to perform a reciprocating scraping process along the pasting direction until the surface is scraped to a flat state; S55: applying a protective layer on the surfaces of the U-shaped carbon fiber cloth 3 and the strip-shaped carbon fiber cloth 5.

[0020] As a preference, in step 2 S1 and in step 5 S52, a grinder is used to grind the concrete surface.

[0021] In order to ensure the subsequent bonding strength, in step three S32, after the inner surface is blown clean, an interface agent is applied to the inner surface of the beam opening 1 and dried for a set time.

[0022] In order to improve the reinforcement effect of the concrete beam and ensure the effect of suppressing crack extension, in step 5 S54, the thickness of the U-shaped carbon fiber cloth 3 and the strip carbon fiber cloth 5 are both greater than 0.1 mm, and the width thereof are both 50-100 mm.

[0023] In order to effectively suppress the extension of the crack in the left-right direction, in step 5 S54, the distance between the two U-shaped carbon fiber cloths 3 on the same side is 50-200 mm.

[0024] In order to ensure the firmness of the adhesion between the U-shaped carbon fiber cloth and the concrete beam, in step 5 S52, when grinding the U-shaped adhesive tape, if the corner of the concrete beam 6 is a right angle, the right angle is ground into a rounded corner.

[0025] In order to effectively transfer the shear force and thereby effectively restore the loss of shear bearing capacity of the concrete beam caused by the opening, in step 4 S41, the thickness of the steel pipe 2 is greater than 2 mm.

[0026] In order to improve the reinforcement effect, in step 4 S44, the chemical bolt 4 is in an inverted cone shape.

[0027] In the present invention, the drilled beam opening is first polished, and then the inner surface of the beam opening is cleaned by using a blower, which can ensure that the steel pipe inserted later can be firmly and reliably connected to the inside of the beam opening through structural adhesive. The steel pipe is inserted into the inside of the beam opening, and the outer surface of the steel pipe main section and the inner surface of the beam opening main section are connected by structural adhesive, and then the small gap between the end of the steel pipe and the end of the beam opening is filled and reinforced by structural adhesive, which can effectively improve the bonding strength between the steel pipe and the beam opening, and then reliably combine the steel pipe and the concrete beam into a whole, so as to significantly improve the ability of the steel pipe and the concrete beam to transmit shear force. The added steel pipe can effectively transmit shear force, and can reduce the stress concentration effect at the corner of the beam opening, thereby effectively restoring the loss of shear bearing capacity of the concrete beam caused by the opening. On this basis, the steel pipe is anchored inside the concrete beam by chemical bolts, and the nut of the chemical bolt is welded on the steel pipe. In this way, not only the bonding strength between the steel pipe and the concrete beam and the ability to transmit shear force between the steel pipe and the concrete beam are further improved, but also the overall seismic strength after bonding can be improved, which can ensure that the steel pipe can be firmly connected to the inside of the beam opening by chemical bolts in turn under vibration. Two U-shaped carbon fiber cloths are connected on the left and right sides of the beam opening, and at the same time, a strip of carbon fiber cloth is connected on the upper and lower sides of the beam opening. On the one hand, the two strips of carbon fiber cloths on the same side and the four U-shaped carbon fiber cloths can be used to form a closed inhibition area on the outside of the end of the beam opening, so as to effectively inhibit the cracks on the concrete beam after the opening from extending outward from the end of the opening. On the other hand, the U-shaped carbon fiber cloth can be used to cover the side and bottom of the concrete beam at the same time, so as to effectively inhibit the cracks on the concrete beam after the opening from extending outward from the main area of ​​the opening. Applying a protective layer on the surface of the carbon fiber cloth can play a further reinforcement role and effectively prevent the occurrence of cracks.

[0028] Through a large number of experiments and practices, the present invention can improve the ultimate bearing capacity of the concrete beam after the hole is opened by about 10%. At the same time, it can effectively prevent the extension of cracks on the concrete beam after the hole is opened, ensuring the shear resistance and bearing strength of the concrete beam after the hole is opened. The method has a simple operation process and low implementation cost, can reliably reinforce the concrete beam after the hole is opened, and can realize the programmed construction of the concrete beam hole reinforcement, which is suitable for large-scale promotion and application.

Claims

1. A performance-based comprehensive reinforcement method for reinforced concrete beams with web openings, characterized in that: The following steps are involved: Step 1: Create a beam opening (1); A circular beam opening (1) is provided on the concrete beam (6); Step 2: Inner surface treatment of beam opening (1); S21: grinding the inner surface of the beam opening (1); S22: For the holes and sunken areas on the inner surface caused by grinding, use repair glue to fill them; for deeper holes, use high-grade cement slurry to fill them; Step 3: Drilling holes in the hole; S31: firstly determine the distribution position of the chemical bolts (4) according to the actual project, and then perform drilling operations in the hole according to the determined distribution position; S32: Use a blower to clean the inner surface of the beam opening (1); Step 4: embedding the steel pipe (2) and driving the chemical bolt (4); S41: prefabricating a steel pipe (2) having a size matching that of the beam opening (1) in a factory; S42: opening a through hole in the steel pipe (2) at a position corresponding to the hole drilled in the beam opening (1); S43: first, evenly apply structural adhesive on the outer surface of the steel pipe (2), and then insert the steel pipe (2) into the beam opening (1). During the insertion process, ensure that the positions of the through holes and the drilled holes correspond to each other. At the same time, ensure that the end of the steel pipe (2) is flush with the end of the beam opening (1), and use structural adhesive to fill and reinforce the small gap between the end of the steel pipe (2) and the end of the beam opening (1); S44: installing a chemical bolt (4) in each through hole and allowing the chemical bolt (4) to penetrate into the corresponding drilled hole, and then fixing and connecting the nut of the chemical bolt (4) to the steel pipe (2) by welding; Step 5: Paste the U-shaped carbon fiber cloth (3) and the strip carbon fiber cloth (5); S51: two U-shaped adhesive tapes are respectively formed on the surface of the concrete beam (6) at the left and right sides of the beam opening (1), wherein the U-shaped adhesive tapes are in a U-shape and simultaneously cover the two side surfaces and the bottom surface of the concrete beam (6); and a strip adhesive tape extending transversely is respectively formed on the surface of the concrete beam (6) at the upper and lower sides of the beam opening (1); S52: grinding the U-shaped adhesive tape and the strip adhesive tape respectively, and filling the holes and concave areas caused by grinding; S53: Blow the U-shaped adhesive tape and the strip adhesive tape clean with a blower, then apply an interface agent to the U-shaped adhesive tape and the strip adhesive tape, and dry for a set time; S54: first, evenly apply the structural adhesive to the U-shaped adhesive tape and the strip adhesive tape, then paste the U-shaped carbon fiber cloth (3) on the U-shaped adhesive tape, and paste the strip carbon fiber cloth (5) on the strip adhesive tape, wherein the U-shaped carbon fiber cloth (3) simultaneously covers the side and bottom surfaces of the concrete beam (6) in a U-shape, and at the same time, the two ends of the strip carbon fiber cloth (5) extend to the outside of the U-shaped carbon fiber cloth (3) on both sides, and the two strip carbon fiber cloths (5) on the side cooperate with the four U-shaped carbon fiber cloths (3) to form a closed inhibition area on the outside of the beam opening (1), and then, use a plastic scraper to perform a reciprocating scraping process along the pasting direction until the surface is scraped to a flat state; S55: A protective layer is applied to the surfaces of the U-shaped carbon fiber cloth (3) and the strip-shaped carbon fiber cloth (5).

2. A performance-based comprehensive reinforcement method for reinforced concrete beams with web openings according to claim 1, characterized in that: In step 2 S1 and in step 5 S52, a grinder is used to grind the concrete surface.

3. A performance-based comprehensive reinforcement method for reinforced concrete beams with web openings according to claim 1 or 2, characterized in that: In step 3 S32, after the inner surface is blown clean, an interface agent is applied to the inner surface of the beam opening (1) and dried for a set time.

4. A performance-based comprehensive reinforcement method for reinforced concrete beams with web openings according to claim 3, characterized in that: In step five, S54, the thickness of the U-shaped carbon fiber cloth (3) and the strip-shaped carbon fiber cloth (5) are both greater than 0.1 mm, and their widths are both 50 to 100 mm.

5. A performance-based comprehensive reinforcement method for reinforced concrete beams with web openings according to claim 4, characterized in that: In step 5 S54, the distance between the two U-shaped carbon fiber cloths (3) on the same side is 50 to 200 mm.

6. A performance-based comprehensive reinforcement method for reinforced concrete beams with web openings according to claim 5, characterized in that: In step 5 S52, when grinding the U-shaped adhesive tape, if the corner of the concrete beam (6) is a right angle, the right angle is ground into a rounded corner.

7. A performance-based comprehensive reinforcement method for reinforced concrete beams with web openings according to claim 6, characterized in that: In step 4 S41, the thickness of the steel pipe (2) is greater than 2 mm.

8. A performance-based comprehensive reinforcement method for reinforced concrete beams with web openings according to claim 7, characterized in that: In step 4 S44, the chemical bolt (4) is in an inverted cone shape.

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