Construction method for enlarging section and reinforcing existing building beam column
By setting up triangular prism steel structure and closed-loop column stirrup connection at the beam-column nodes of existing buildings, the problems of excessive embedded steel bars that easily damage the original structure and long construction period in traditional reinforcement methods are solved, achieving efficient and economical reinforcement effects and improving seismic performance and bearing capacity.
Patent Information
- Application Number
- CN202511049686.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2025-09-09
AI Technical Summary
In the traditional method of increasing the cross-section of existing building beams and columns to strengthen them, the stirrup setting does not meet the building's stress requirements, too much embedded reinforcement can easily damage the original structure, the construction period is long, the efficiency is low, and the traditional method is complex and difficult to meet the seismic performance requirements.
At the beam-column joints of existing buildings, triangular prism steel structures and closed-loop column stirrups are installed to form an enlarged cross-sectional area, reduce the number of embedded bars, enhance the bonding between new and old concrete, and use triangular stirrups and column reinforcement to increase local stiffness and bearing capacity to meet regulatory requirements.
It achieves convenient construction, better economy, shortens construction period, improves seismic performance and overall bearing capacity, avoids damage to the original structure caused by embedded reinforcement, and simplifies the construction process.
Smart Images
Figure CN120608609A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of reinforcement of existing building structures, in particular to a construction method for reinforcing existing building beams and columns by increasing their cross-sections. Background Art
[0002] Urban renewal often involves the structural renovation and reinforcement of existing buildings, including structural adjustments driven by functional transformation, improvements to earthquake resistance and disaster preparedness, and the need to extend the building's service life. Structural renovation and reinforcement can improve building safety, functionality, and service life, while preserving cultural memory, reducing resource waste, and achieving comprehensive economic, social, and environmental benefits.
[0003] Reinforcement by increasing cross-section is one of the most common reinforcement methods for beams and columns in existing buildings. According to the "strong node" design principle, the effective implementation of column node reinforcement is one of the difficulties of the frame column increased cross-section reinforcement method. The traditional column node reinforcement by increasing cross-section is to use equal-generation stirrups to pass through the longitudinal and transverse beams in the beam area and then weld them together. The disadvantages of the traditional method are as follows: 1. A large number of holes are opened in the floor beams for passing reinforcement, which can easily damage the original structure and the wet operation time is long, and the overall construction cost is high. This patented method greatly reduces the number of embedded reinforcements and is more economical; 2. Some structures (such as steel-concrete columns) cannot be embedded with reinforcement, which limits the application of this method; 3. The traditional node construction method requires embedding stirrups in sections first, and then welding the segmented stirrups into an integral closed stirrup, which makes the construction method complicated and increases the difficulty of construction. The construction period is long and the overall work efficiency is low; 4. If the spacing of the equivalent stirrups is greater than the spacing limit of the node stirrup densification area in the specification, the seismic performance will be unfavorable; if the spacing of the embedded reinforcement is too small, the bond strength of the concrete is insufficient, and the pull-out bearing capacity of the embedded reinforcement cannot be guaranteed, so the specification has a minimum spacing requirement for embedded reinforcement; if the spacing of the equivalent stirrups is reduced, the number needs to be increased, which is not economical; 5. When the beams with prefabricated panels placed on the upper part are reinforced with an enlarged cross-section, the traditional practice is to set the beam stirrups according to the spacing requirements of the specification and embed them through the original beams and then weld them to form closed stirrups. The disadvantage is that the embedding work is easy to damage the original structure, the economy is low, and the construction period is long. Summary of the Invention
[0004] The present invention provides a construction method for increasing the cross-section and reinforcing the beams and columns of an existing building, which can solve the problems in the traditional construction method that the stirrup arrangement does not meet the stress requirements of the building, too much embedded reinforcement easily damages the original structure, the construction period is long, the construction efficiency is low, and the amount of steel bars used is large. The invention has the advantages of improving construction efficiency and seismic resistance, and achieving the reinforcement construction goals of optimizing the process and reducing the construction period.
[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A construction method for increasing the cross-section and reinforcing beams and columns of an existing building comprises increasing the cross-section at the beam-column joints of the existing building. At the joints between the existing columns and the four-way overlapping existing beams, four areas separated by the existing beams are provided with increased cross-section areas for the existing columns. The reinforcement in each increased cross-section area comprises a triangular prism-shaped reinforcement structure consisting of three column longitudinal bars and a plurality of triangular stirrups. The three column longitudinal bars include one at the outer corner of the column and one each at the longitudinal and transverse beam sides. The four triangular prism-shaped reinforcement structures are connected by a plurality of closed-loop column stirrups. The reinforced node is divided into four areas by the existing frame columns and frame beams. Triangular hoops are first set in the four small areas to constrain the concrete in the small areas and improve the regional shear and local compression bearing capacity. The four triangular prism steel structures are fixed to each other's positions through several closed-loop column hoops.
[0006] The triangular prism steel structure is connected to the existing columns on both sides through horizontal and transverse column-like stirrups, and the ends of the column-like stirrups are respectively implanted into the interior of the existing beams; the connection and fixation between the triangular prism steel structure and the existing building are achieved through the column-like stirrups, so that each triangular prism steel structure forms a whole with the original structure.
[0007] The three column longitudinal bars in the enlarged cross-section area are connected to horizontal column reinforcements between the two inner ones, and the horizontal height of the column reinforcements is equal to that of the equivalent stirrups; the column reinforcements are used as shear reinforcements between the new and old concrete to enhance the bonding between the new and old concrete.
[0008] The construction method of increasing the cross-section and reinforcing the nodes on the four sides of the existing column includes the following steps: (1) Roughening of the concrete surface of existing beams and columns at the node locations; (2) The longitudinal reinforcement of the column is planted through the original floor slab, and the high section of the beam at the beam-column node is separated by the original beam into four small areas with enlarged cross-sections; (3) Several triangular stirrups are set at the high section of the beam-column joint. The stirrup diameter is one level larger than the calculated value, and the stirrup spacing is in accordance with the requirements of the column densification area in the specification; (4) Set equal-substitute stirrups at the beam-column joint high section and embed them into or through the original beam. At the same time, set column reinforcement to connect the longitudinal reinforcement of the beam side column in the area with enlarged cross-section. The horizontal setting position of the column reinforcement is the same as that of the equal-substitute stirrups; (5) Pour concrete.
[0009] The distance between the column and equal stirrups is ≥100mm from the bottom of the slab, the distance between the equal stirrups and the bottom of the beam is ≥250mm, and the spacing between the equal stirrups is 500~600mm.
[0010] The sum of the cross-sectional areas of the equivalent stirrups is equal to the sum of the calculated areas of the stirrups in the high section of the beam.
[0011] The upper end surface of the existing beam is closely attached to the original floor slab, and the existing beam is provided with an enlarged cross-section area on the left and right sides of the cross-section. Two beam surface bars in the same direction as the beam extension are provided on the upper part of the enlarged cross-section area, and two beam bottom bars in the same direction as the beam extension are provided on the lower part. The beam stirrups surround and connect the beam surface bars and the beam bottom bars on one side, and then pass through the lower bottom surface of the existing beam and the beam surface bars and the beam bottom bars on the other side to surround and connect them. By setting closed stirrups in the newly added wide sections on the left and right sides of the beam and connecting them through the bottom of the beam, the shear bearing capacity of the newly added sections on both sides of the beam is ensured.
[0012] Shear reinforcement is respectively arranged in the middle of both sides of the existing beam section, one end of the shear reinforcement is connected to the beam stirrup, and the other end is embedded in the existing beam; the shear reinforcement is used as shear reinforcement between new and old concrete to enhance the bonding between new and old concrete.
[0013] A rectangular closed-loop beam-substitute stirrup is set on the existing beam cross-section, the upper reinforcement of the beam-substitute stirrup passes through the interior of the cross-section of the existing beam, and the lower reinforcement of the beam-substitute stirrup passes through the bottom surface of the existing beam; large stirrups of beam-substitute stirrups implanted through the original beam are used to form the newly added cross-sections on the left and right sides and the original beam into a whole, thereby ensuring the overall bearing capacity.
[0014] The construction method for widening the cross-section and reinforcing the existing beam on both sides includes the following steps: (1) Roughening the interface between new and old concrete of existing beams; (2) Beam longitudinal reinforcement setting: At least four longitudinal reinforcements are set on each side of the beam, including two surface reinforcements and two bottom reinforcements; (3) The beam stirrups are bent into a closed stirrup on each side of the widened cross-section area on both sides of the beam. A groove is cut at the bottom of the beam, and the beam stirrups pass through the groove. The stirrup diameter is one level larger than the calculated value, and the stirrup spacing is in accordance with the specifications and calculation requirements; (4) Set up the beam substitute stirrups. The upper part of the substitute stirrups is planted through the original beam. A groove is cut at the bottom of the beam, and the lower part of the substitute stirrups passes through the groove. (5) Pour concrete.
[0015] The spacing between the equivalent stirrups is 1000mm, and the cross-sectional area of a single equivalent stirrup is equal to the sum of the calculated areas of the stirrups within the 1-meter beam span.
[0016] The 1000mm area near the node area is the reinforced section, with a layout density of 100mm per hoop, and the rest is the non-reinforced section, with a layout density of 200mm per hoop. The local reinforced section enhances the local stiffness and bearing capacity of the node.
[0017] This application includes the following beneficial technical effects: 1. The construction method is convenient, the number of embedded reinforcements is greatly reduced, and there is no need to embed reinforcement on existing columns. Only limited embedding of reinforcement is required on existing beams, thus avoiding the situation where steel-concrete columns cannot be embedded with reinforcement. Compared with traditional methods, it saves a lot of embedding work, shortens the construction period, and has a lower cost.
[0018] 2. The spacing of stirrups meets specifications and calculation requirements, eliminating the need for planted reinforcement. This avoids the possibility of missing stirrups when planting reinforcement is not possible due to the need to avoid existing beam reinforcement or steel sections. Furthermore, the stirrup area of this patented method meets calculation requirements, ensuring the shear bearing capacity of reinforced concrete components while significantly reducing the number of planted reinforcements, resulting in superior economic efficiency.
[0019] 3. The local areas of the newly added sections in the columns and beams have better local stiffness due to the setting of closed small hoops, and the shear bearing capacity of the reinforced sections is better.
[0020] 4. High construction operability, solving the location limitation problem of traditional methods (difficulty in inserting stirrups in the slab bottom area into the beam). This patented construction method can meet the calculation requirements for the stirrup area, ensuring the shear bearing capacity of reinforced concrete components, while significantly reducing the number of embedded bars, resulting in better economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is the elevation structure diagram of the beam-column node; (inverted) Figure 2 Schematic diagram of the facade structure for increasing the cross-section of existing columns and arranging reinforcement; Figure 3 This is a rough cross-sectional view of an existing column; Figure 4 Set up cross-sectional structural diagrams for column longitudinal reinforcement; Figure 5 Set up cross-sectional structural diagrams for triangular stirrups; Figure 6 Set up cross-sectional structural diagrams for column stirrups and column ties; Figure 7 Increase the cross-section of the existing beam to arrange the steel bars and provide a perspective structural elevation diagram; Figure 8 Provide perspective structural diagrams of beam stirrups and beam equal stirrups; Figure 9 The rough cross-section diagram of the existing beam; Figure 10 Increase the cross-section of existing beams to arrange the cross-section structure diagram; Figure 11 Set up cross-sectional structural diagrams for beam surface reinforcement and beam bottom reinforcement; Figure 12 Set up cross-sectional structural diagrams for beam stirrups; Figure 13 Set up cross-sectional structural diagrams for beams with equivalent stirrups and shear reinforcement; Figure 14 This is a schematic diagram of the welding position of the beam and other substitute stirrups; Figure 15 Main structural drawing of the existing beam with increased cross-section reinforcement arrangement; Figure 16 This is a photo of the actual arrangement of steel bars at the construction site of the application example; The serial numbers and component names in the figure are: 1-existing column; 11-column longitudinal reinforcement; 12-triangular stirrups; 13-column stirrups; 14-column tension reinforcement; 15-column stirrups; 2-existing beam; 21-beam surface reinforcement; 22-beam bottom reinforcement; 23-beam stirrups; 24-beam stirrups; 25-shear reinforcement; 3-original floor slab. DETAILED DESCRIPTION
[0022] Example 1
[0023] A construction method for increasing the cross-section and reinforcing beams and columns in an existing building, comprising: increasing the cross-section at the beam-column joints of an existing building; at the joints between an existing column 1 and an existing beam 2 overlapping four directions, four areas separated by the existing beam 2 are provided with increased cross-section areas for the existing column 1; the reinforcement in each increased cross-section area comprises a triangular prism-shaped reinforcement structure consisting of three column longitudinal bars 11 and a plurality of triangular stirrups 12, wherein the three column longitudinal bars 11 include one at the outer corner of the column and one each at the longitudinal and transverse beam sides; the four triangular prism-shaped reinforcement structures are connected by a plurality of closed-loop column stirrups 15; The triangular prism steel structure is connected to the existing columns 1 on both sides through horizontal column-substitute stirrups 13, and the ends of the column-substitute stirrups 13 are respectively embedded in the interior of the existing beams 2; The three column longitudinal bars 11 in the enlarged cross-section area are connected to the two inner column longitudinal bars 11, and the horizontal height of the column tie bars 14 is equal to that of the equivalent stirrups 13; The construction method of increasing the cross-section and reinforcing the nodes on the four sides of the existing column includes the following steps: (1) Roughening of the concrete surface of existing beams and columns at the node locations; (2) The longitudinal reinforcement of the column is planted through the original floor slab, and the high section of the beam at the beam-column node is separated by the original beam into four small areas with enlarged cross-sections; (3) Several triangular stirrups are set at the high section of the beam-column joint. The stirrup diameter is one level larger than the calculated value, and the stirrup spacing is in accordance with the requirements of the column densification area in the specification; (4) Set equal-substitute stirrups at the beam-column joint high section and embed them into or through the original beam. At the same time, set column reinforcement to connect the longitudinal reinforcement of the beam side column in the area with enlarged cross-section. The horizontal setting position of the column reinforcement is the same as that of the equal-substitute stirrups; (5) Pour concrete.
[0024] The distance between the column and equal stirrups is ≥100mm from the bottom of the slab, the distance between the equal stirrups and the bottom of the beam is ≥250mm, and the spacing between the equal stirrups is 500~600mm.
[0025] The sum of the cross-sectional areas of the equivalent stirrups is equal to the sum of the calculated areas of the stirrups in the high section of the beam.
[0026] The upper end surface of the existing beam 2 is closely attached to the original floor slab 3, and the existing beam 2 is provided with an enlarged cross-section area on the left and right sides of the cross-section. Two beam surface bars 21 are provided on the upper part of the enlarged cross-section area in the same direction as the beam extension, and two beam bottom bars 22 are provided on the lower part in the same direction as the beam extension. The beam stirrups 23 surround and connect the beam surface bars 21 and the beam bottom bars 22 on one side, and then pass through the lower bottom surface of the existing beam 2 and the beam surface bars 21 and the beam bottom bars 22 on the other side to surround and connect them. Shear reinforcement 25 is respectively provided at the middle of both sides of the cross section of the existing beam 2, one end of the shear reinforcement 25 is connected to the beam stirrup 23, and the other end is embedded in the existing beam 2; A rectangular closed-loop stirrup 24 is provided on the cross section of the existing beam 2. The upper stirrup 24 passes through the cross section of the existing beam 2, and the lower stirrup 24 passes through the lower surface of the existing beam 2. The construction method for widening the cross-section and reinforcing the existing beam on both sides includes the following steps: (1) Roughening the interface between new and old concrete of existing beams; (2) Beam longitudinal reinforcement setting: At least four longitudinal reinforcements are set on each side of the beam, including two surface reinforcements and two bottom reinforcements; (3) The beam stirrups are bent into a closed stirrup on each side of the widened cross-section area on both sides of the beam. A groove is cut at the bottom of the beam, and the beam stirrups pass through the groove. The stirrup diameter is one level larger than the calculated value, and the stirrup spacing is in accordance with the specifications and calculation requirements; (4) Set up the beam substitute stirrups. The upper part of the substitute stirrups is planted through the original beam. A groove is cut at the bottom of the beam, and the lower part of the substitute stirrups passes through the groove. (5) Pour concrete.
[0027] The spacing between the equivalent stirrups is 1000mm, and the cross-sectional area of a single equivalent stirrup is equal to the sum of the calculated areas of the stirrups within the 1-meter beam span.
[0028] The 1000mm area of the beam stirrups close to the node area is the densified section, with a layout density of 100mm per stirrup, and the rest is the non-densified section, with a layout density of 200mm per stirrup.
[0029] Application examples: A four-story museum, 42 years old, was undergoing renovation and expansion. The building was enlarged from a small to a medium-to-large museum, increasing the exhibition hall load and altering the building layout. The original structure was a frame structure, with typical column cross-section dimensions of 400x350mm and a total column height of approximately 21m. The original beam cross-section dimensions were 250x700mm, with a span of 9m. Reinforcement calculations determined that the columns required a 150mm increase on each side, while the beams required a 100mm increase on each side.
[0030] The amount of steel bars used and the planting conditions at each beam-column node, and the economic efficiency comparison between the present invention and the traditional construction method are as follows: The reinforcement arrangement of traditional construction is based on the atlas "Drawing Rules for Overall Representation of Planes in Concrete Structure Construction Drawings and Structural Details (Cast-in-place Concrete Frames, Shear Walls, Beams, and Slabs)" (22G101-1). For the reinforcement construction work of post-embedded reinforcement, the reinforcement arrangement in the atlas is too dense and difficult to implement.
[0031]
[0032] After force analysis and calculation, the structural bearing capacity comparison between the present invention and the traditional construction method is as follows:
[0033] From the comparison results, it can be seen that under the requirements of greatly improving the bearing capacity of the beam-column node and achieving the same bearing capacity of the beam, the present invention is more economical than the traditional construction method.
Claims
1. A construction method for increasing the cross-section and reinforcing beams and columns of an existing building, characterized by: The cross-section of the existing building is enlarged at the beam-column node. At the node between the existing column (1) and the four-way existing beam (2) of the building, the four areas separated by the existing beam (2) are respectively provided with enlarged cross-section areas of the existing column (1); the steel bars of each enlarged cross-section area include: a triangular prism steel bar structure composed of three column longitudinal bars (11) and a plurality of triangular stirrups (12), the three column longitudinal bars (11) including one at the outer corner point of the column and one each at the longitudinal and transverse beam sides; the four triangular prism steel bar structures are connected by a plurality of closed-loop column stirrups (15); The triangular prism steel bar structure is connected to the existing columns (1) on both sides via horizontal column-substitute stirrups (13), and the ends of the column-substitute stirrups (13) are respectively implanted into the interior of the existing beams (2); The three column longitudinal bars (11) in the enlarged cross-section area are connected to horizontal column reinforcement bars (14) between the two inner column longitudinal bars (11), and the horizontal height of the column reinforcement bars (14) is equal to that of the equivalent stirrups (13); The construction method of increasing the cross-section and reinforcing the nodes on the four sides of the existing column includes the following steps: (1) Roughening of the concrete surface of existing beams and columns at the node locations; (2) The longitudinal reinforcement of the column is planted through the original floor slab, and the high section of the beam at the beam-column node is separated by the original beam into four small areas with enlarged cross-sections; (3) Several triangular stirrups are set at the high section of the beam-column joint. The stirrup diameter is one level larger than the calculated value, and the stirrup spacing is in accordance with the requirements of the column densification area in the specification; (4) Set equal-substitute stirrups at the beam-column joint high section and embed them into or through the original beam. At the same time, set column reinforcement to connect the longitudinal reinforcement of the beam side column in the area with enlarged cross-section. The horizontal setting position of the column reinforcement is the same as that of the equal-substitute stirrups; (5) Pour concrete.
2. The construction method for increasing the cross-section and reinforcing the existing building beams and columns according to claim 1 is characterized in that: The distance between the column and equal stirrups is ≥100mm from the bottom of the slab, the distance between the equal stirrups and the bottom of the beam is ≥250mm, and the spacing between the equal stirrups is 500~600mm.
3. The construction method for increasing the cross-section and reinforcing the existing building beams and columns according to claim 1 is characterized in that: The sum of the cross-sectional areas of the equivalent stirrups is equal to the sum of the calculated areas of the stirrups in the high section of the beam.
4. The construction method for increasing the cross-section and reinforcing the existing building beams and columns according to claim 1 is characterized in that: The upper end surface of the existing beam (2) is in close contact with the original floor slab (3); the existing beam (2) is provided with an enlarged cross-section area on the left and right sides of its cross-section; two beam surface bars (21) are provided on the upper part of the enlarged cross-section area in the same direction as the beam extension; two beam bottom bars (22) are provided on the lower part in the same direction as the beam extension; the beam stirrups (23) are connected to the beam surface bars (21) and the beam bottom bars (22) on one side through a circle, and then pass through the lower bottom surface of the existing beam (2) to connect the beam surface bars (21) and the beam bottom bars (22) on the other side through a circle; Shear reinforcement (25) is respectively provided at the middle of both sides of the cross section of the existing beam (2), one end of the shear reinforcement (25) is connected to the beam stirrup (23), and the other end is implanted inside the existing beam (2); A rectangular closed-loop beam-substitute stirrup (24) is provided on the cross section of the existing beam (2), the upper reinforcement of the beam-substitute stirrup (24) passes through the interior of the cross section of the existing beam (2), and the lower reinforcement of the beam-substitute stirrup (24) passes through the lower bottom surface of the existing beam (2); The construction method for widening the cross-section and reinforcing the existing beam on both sides includes the following steps: (1) Roughening the interface between new and old concrete of existing beams; (2) Beam longitudinal reinforcement setting: At least four longitudinal reinforcements are set on each side of the beam, including two surface reinforcements and two bottom reinforcements; (3) The beam stirrups are bent into a closed stirrup on each side of the widened cross-section area on both sides of the beam. A groove is cut at the bottom of the beam, and the beam stirrups pass through the groove. The stirrup diameter is one level larger than the calculated value, and the stirrup spacing is in accordance with the specifications and calculation requirements; (4) Set up the beam substitute stirrups, and plant the upper part of the substitute stirrups through the original beam. Cut a groove at the bottom of the existing beam, and pass the lower part of the beam substitute stirrups through the groove; (5) Pour concrete.
5. The construction method for increasing the cross-section and reinforcing the existing building beams and columns according to claim 4 is characterized in that: The spacing between the equivalent stirrups is 1000mm, and the cross-sectional area of a single equivalent stirrup is equal to the sum of the calculated areas of the stirrups within the 1-meter beam span.
6. The construction method for increasing the cross-section and reinforcing the existing building beams and columns according to claim 4 is characterized in that: The 1000mm area of the beam stirrups close to the node area is the densified section, with a layout density of 100mm per stirrup, and the rest is the non-densified section, with a layout density of 200mm per stirrup.