Design method for strengthening reinforced concrete frame beam-column intermediate joints by adding wing walls

Abstract

The present invention provides a method for reinforcing the intermediate nodes of reinforced concrete frame beams and columns by adding wing walls. The method comprises the following steps: determining the failure mode of the reinforced concrete frame and whether reinforcement is required; if the node is determined to require earthquake-resistant reinforcement; taking the bending strength of the node as a goal to be greater than the bending strength of the beam, calculating the reinforcement requirement of the node; determining the parameters for adding wing walls according to the reinforcement requirement of the node, thereby reinforcing the intermediate nodes of the reinforced concrete frame beams and columns. The method solves the problem that the material and geometric parameters of the wing walls cannot be quantitatively designed when the intermediate nodes of the beams and columns of the reinforced concrete frame are reinforced by adding wing walls in engineering. The method realizes the determination of whether the existing structure needs reinforcement; and for the structure determined to need reinforcement, quantitatively calculating the reinforcement requirement, thereby determining the concrete strength of the wing walls, the reinforcement of the wing walls, the number of embedded bars, and the size of the wing walls.

Description

Technical Field

[0001] The invention belongs to the technical field of earthquake resistance of construction engineering, and particularly relates to a design method for reinforcing intermediate nodes of reinforced concrete frame beams and columns by adding wing walls. Background Art

[0002] Newly issued engineering seismic design codes impose increasingly stringent safety requirements on building structures, such as increased load partial factors and safety factors. As a result, many older buildings fail to meet the requirements when evaluated against the new codes. Furthermore, many older buildings, particularly those in rural areas, were not professionally designed by engineers, relying solely on the experience of the owners and construction teams. In some projects, construction personnel lack professional expertise, and on-site management is lax, resulting in construction not following the design drawings. This results in structural details not meeting seismic requirements, such as insufficient or no stirrups at beam-column joints.

[0003] "Strong columns and weak beams, strong shear and weak bending, strong nodes and weak components" is a basic principle that should be followed in the seismic design of building structures. However, earthquake disaster surveys at home and abroad have shown that many reinforced concrete frames have suffered shear failure at the beam-column nodes during earthquakes. The shear failure of the nodes is a brittle failure with low energy dissipation capacity, and it is easy to form an overall collapse mechanism of the building structure, which cannot achieve the seismic fortification goal of "not collapsing in a major earthquake". For the seismic reinforcement of reinforced concrete frame beam-column nodes, scholars at home and abroad have proposed methods such as pasting carbon fiber cloth around the nodes and adding steel supports at the beam ends, but these methods have defects such as high engineering costs, difficult construction, poor fire resistance and durability.

[0004] Adding reinforced concrete wing walls to the sides of existing frame columns is a widely used seismic reinforcement method for frame columns. Furthermore, studies have demonstrated through experiments and numerical simulations that this method can effectively improve the bearing capacity of beam-column joints, preventing joint failure before beam-column components under earthquake action. Adding reinforced concrete wing walls not only improves the seismic performance of reinforced concrete columns but also improves the seismic performance of beam-column joints, creating an ideal beam-end bending failure mode. This method requires simple material acquisition, is easy to construct, is unaffected by orthogonal beams, is low-cost, and offers excellent fire resistance and durability, making it an ideal seismic reinforcement method for beam-column joints. However, as a new seismic reinforcement method for reinforced concrete beam-column joints, the wing wall method is currently in the laboratory validation stage, with no precedent for engineering application and no experience to serve as a reference for engineering design. A design method is needed to address the issue of determining wing wall parameters when reinforcing existing reinforced concrete beam-column joints in engineering. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that when the wing wall method is used to reinforce the middle nodes of beams and columns of reinforced concrete frames in engineering, the material and geometric parameters of the wing walls cannot be quantitatively designed. A method for reinforcing the middle nodes of beams and columns of reinforced concrete frames by adding wing walls is proposed to determine whether the existing structure needs to be reinforced. For structures that are determined to need reinforcement, the reinforcement requirements are quantitatively calculated to determine the concrete strength of the wing walls, the wing wall reinforcement, the number of embedded bars, and the wing wall dimensions.

[0006] The present invention is achieved through the following technical solutions:

[0007] A design method for strengthening the intermediate joints of reinforced concrete frame beams and columns by adding wing walls, comprising:

[0008] S1, when bending failure occurs at the dangerous section, the bending moment at the node center of the left beam is obtained by calculation. j M bu,l , the bending moment at the node center corresponding to the right beam j M bu,r , the bending moment at the center of the node corresponding to the upper column j M cu,t And the bending moment at the node center corresponding to the lower column j M cu,d , determine the failure mode of the reinforced concrete frame and whether it needs seismic reinforcement. If it is determined that the node needs seismic reinforcement;

[0009] S2, with the goal of making the bending strength of the node greater than the bending strength of the beam, calculates the required reinforcement of the node;

[0010] S3, determine the parameters of adding wing walls based on the reinforcement requirements of the nodes, thereby achieving the reinforcement of the middle nodes of reinforced concrete frame beams and columns.

[0011] Preferably, the specific process of S1 is:

[0012] According to the cross-sectional dimensions, reinforcement and material strength of the reinforced concrete frame components, the bending bearing capacity of the left beam M is calculated. bu,l , right beam bending bearing capacity M bu,r , Upper column bending bearing capacity M cu,t , lower column bending bearing capacity M cu,d and the node bending capacity M ju , and then calculate the bending moment at the node center of the left beam when bending failure occurs at the dangerous section j M bu,l , the bending moment at the node center corresponding to the right beam j M bu,r , the bending moment at the center of the node corresponding to the upper column j M cu,t And the bending moment at the node center corresponding to the lower columnj M cu,d ;

[0013] contrast j M bu,l + j M bu,r , j M cu,t + j M cu,d and M ju The size of the reinforced concrete frame is used to determine the failure mode of the reinforced concrete frame;

[0014] like j M bu,l + j M bu,r At the minimum, the failure mode of reinforced concrete frame is beam bending failure, which is an ideal failure mode and does not require reinforcement;

[0015] like j M cu,t + j M cu,d At the minimum, the failure mode of reinforced concrete frames is column bending failure, which requires seismic reinforcement of the columns;

[0016] If M ju At the very least, the failure mode of the reinforced concrete frame is node failure, which does not meet the requirements of the seismic code for strong nodes and weak components, so the nodes need to be seismically reinforced.

[0017] Preferably, the bending moment at the node center corresponding to the left beam is j M bu,l The calculation process is:

[0018]

[0019] Where: M bu,l is the bending bearing capacity of the left beam, l b is the length of the beam, l b / 2 is the length of the half-length beam, h c is the column section width, h c / 2 is the half-section width of the column.

[0020] Preferably, the bending moment at the node center corresponding to the right beam is j M bu,r The calculation process is:

[0021]

[0022] Where: M bu,r is the bending capacity of the right beam, l b is the length of the beam, l b / 2 is the length of the half-length beam, hc is the column section width, h c / 2 is the half-section width of the column.

[0023] Preferably, the bending moment at the node center corresponding to the upper column is j M cu,t The calculation process is:

[0024]

[0025] Where: M cu,t is the bending bearing capacity of the upper column, l c is the height of the column, l c / 2 is the height of the half-height column, h b is the beam section height, h b / 2 is the half-section height of the beam.

[0026] Preferably, the bending moment at the node center corresponding to the lower column is j M cu,d The calculation process is:

[0027]

[0028] Where: M cu,d is the bending bearing capacity of the lower column, l c is the height of the column, l c / 2 is the height of the half-height column, h b is the beam section height, h b / 2 is the half-section height of the beam.

[0029] Preferably, the calculation formula for the reinforcement requirement of the node is:

[0030] M 需 =( j M bu,l + j M bu,r )-M ju (5)

[0031] Where: M 需 To strengthen the demand, j M bu,l is the bending moment at the node center corresponding to the left beam, j M bu,r is the bending moment at the node center of the right beam, M ju is the node bending capacity;

[0032] Preferably, the conditions for adding wing walls to meet reinforcement requirements are:

[0033] C w ·l cw >M 需(6)

[0034] Where: C w To generate pressure in the additional upper column wing wall; cw The pressure C generated in the added upper column wing wall w Distance to the node center; C w ·l cw The pressure C generated in the added upper column wing wall w Moment about the center of a node.

[0035] Preferably, the parameters of the wing wall include the amount of column anchor bars, the amount of beam anchor bars, the amount of wing wall longitudinal bars, the amount of wing wall transverse bars, the concrete compressive strength f c , Wing wall thickness b w and wing wall length l w ;

[0036] The amount of column anchor bars and beam anchor bars is determined according to the structural requirements of anchor bars in industry specifications. The amount of wing wall longitudinal bars is configured based on the total cross-sectional area of ​​the wing wall longitudinal bars being larger than the total cross-sectional area of ​​the beam anchor bars. The amount of wing wall transverse bars is configured based on the total cross-sectional area of ​​the wing wall transverse bars being larger than the total cross-sectional area of ​​the column anchor bars. The concrete compressive strength f c Take a value greater than the concrete strength of the original structure, the wing wall thickness b w Take less than the column width b c The integer value of .

[0037] Preferably, the wing wall length l w The method for determining is:

[0038] After adding wing walls to the reinforced concrete frame, the cross section of the column changes from square to T-shaped. When the T-shaped cross section reaches full plasticity, a pressure C is generated in the added upper column wing wall. w According to the force balance, we can obtain the formula (7) and (8), that is, the resultant force of the concrete compressive stress is equal to the resultant force of the steel bar tensile stress;

[0039] C w =T y (7)

[0040] T y =f y ·A s (8)

[0041] Where, T y is the total yield tension of the main reinforcement in the column, f y is the yield strength of the steel bar; A s is the total cross-sectional area of ​​the main reinforcement in the column;

[0042] The height x of the concrete compression zone is obtained according to formula (9);

[0043]

[0044] Where, α is the equivalent rectangular stress diagram coefficient of the concrete compression zone, f c is the compressive strength of concrete;

[0045] The pressure C generated in the added upper column wing wall w The distance to the node center l cw , obtained according to formula (10);

[0046]

[0047] Where: h c is the column section width, h c / 2 is the half-section width of the column; x is the height of the concrete compression zone, l w is the wing wall length;

[0048] Combining formula (10) with formulas (5), (6), (7), and (8), we can obtain formula (11);

[0049]

[0050] From formula (11), we can get the wing wall length l w Should meet the following requirements:

[0051]

[0052] Where: j M bu,l is the bending moment at the node center corresponding to the left beam, j M bu,r is the bending moment at the node center of the right beam, M ju is the node bending capacity, b w is the wing wall thickness, f c is the design value of concrete compressive strength, α is the equivalent rectangular stress diagram coefficient of concrete compression zone, A s is the total cross-sectional area of ​​the main reinforcement in the column, h c / 2 is the half-section width of the column, f y is the yield strength of the steel bar.

[0053] Compared with the prior art, the present invention has the following beneficial technical effects:

[0054] The present invention proposes a design method for reinforcing the middle nodes of reinforced concrete frame beams and columns by adding wing walls. When analyzing the seismic performance of reinforced concrete frames, the three-dimensional space structure can be simplified into multiple plane frames, and then one of the plane frames is analyzed, and the middle node is the object. When reinforcing the frame by adding reinforced concrete wing walls, a design method for the wing walls is proposed. Assuming that when the frame is subjected to earthquake action, the bending moment inflection point of the beams and columns is located at the midpoint of the component, the midpoints of the left beam, right beam, upper column, and lower column connected to the middle node are used as boundaries, and the local structure is mechanically analyzed. The reinforcement design method is explained, and the bending moment at the center of the node corresponding to the left beam is obtained by calculation when bending failure occurs at the dangerous section. j M bu,l , the bending moment at the node center corresponding to the right beam j M bu,r , the bending moment at the center of the node corresponding to the upper column j M cu,t And the bending moment at the node center corresponding to the lower column j M cu,d , determine the failure mode of the reinforced concrete frame and whether it needs to be reinforced. If it is determined that the node needs seismic reinforcement; with the bending strength of the node being greater than the bending strength of the beam as the goal, calculate the reinforcement requirement of the node; determine the parameters of the additional wing wall through the reinforcement requirement of the node, thereby realizing the reinforcement of the intermediate nodes of the reinforced concrete frame beams and columns. The method of the present invention can realize the judgment of whether the beam-column nodes of the existing structure need to be seismically reinforced, and realize the quantitative design of the parameters of the wing wall based on the reinforcement target; and through accurate wing wall design, quantitative calculation of reinforcement requirements, and determination of the concrete strength of the wing wall, wing wall reinforcement, number of embedded bars, and wing wall size, to ensure that the reinforcement target is achieved and avoid reinforcement failure. The method of the present invention can calculate the required minimum wing wall length, accurately grasp the safety and economy of the reinforcement project, and avoid labor and material waste caused by excessive reinforcement; provide a design basis for reinforcing beam-column nodes by adding wing walls, and promote the reinforcement and transformation process of existing structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a three-dimensional schematic diagram of the existing reinforced concrete plane frame and the names of its parts;

[0056] Figure 2 This is a schematic diagram of strengthening the joints in reinforced concrete frames by adding wing walls;

[0057] Figure 3 It is the scope of design and analysis of mid-node reinforcement;

[0058] Figure 4 It is the distribution diagram of the bending moment of the mid-node and beam-column under the action of earthquake force;

[0059] Figure 5This is a schematic diagram of the middle node after reinforcement;

[0060] Figure 6 This is a schematic diagram of the force acting on the beam after the reinforcement of the wing wall;

[0061] Figure 7 It is a schematic diagram of the forces around the mid-node after reinforcement;

[0062] Figure 8 It is a parameter diagram of the wing wall;

[0063] Figure 9 It is a schematic diagram of the internal force state of the rear column after the wing wall is added when the full cross-section shaping is achieved.

[0064] In the figure: column 1, beam 2, edge node 3, mid-node 4, foundation beam 5, wing wall 6, column anchor bar 7, beam anchor bar 8, wing wall longitudinal bar 9, wing wall transverse bar 10. DETAILED DESCRIPTION

[0065] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0066] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0067] When analyzing the seismic performance of reinforced concrete frames, the three-dimensional space structure can be simplified into multiple plane frames, and then one of the plane frames is used for analysis. For example, a three-story two-span frame can be simplified into a plane frame. Figure 1 In the figure, columns 1 and 2 are beams, the area where the side columns and beams intersect is the edge node 3, the area where the middle columns and the beams of the middle floors intersect is the middle node 4, and the foundation beam is 5.

[0068] The present invention takes the middle node 4 as the object, when using Figure 2 When reinforcing the frame by adding reinforced concrete wing walls 6, a design method for wing walls is proposed. Assuming that the frame is subjected to earthquake action, the bending moment inflection point of the beam and column is located at the midpoint of the member, with the midpoints of the left beam, right beam, upper column, and lower column connected to the midpoint 4 as the boundary, that is, Figure 3 A mechanical analysis of the local structure within the middle dotted line is performed, and the reinforcement design method is explained.

[0069] 1. Frame failure mode and determination of whether reinforcement is required

[0070] Under horizontal earthquake action, Figure 3 The bending moment and shear force distribution of the local structure within the dotted line is as follows: Figure 4 As shown, assuming the length of the beam is l b , then the length of the half-length beam is l b / 2; Assume the height of the column is l c , then the height of the half-height column is l c / 2.

[0071] First, according to the cross-sectional dimensions, reinforcement and material strength of the components, the bending bearing capacity M of the left beam, right beam, upper column, lower column and node is calculated using the existing standard formula. bu,l 、M bu,r 、M cu,t 、M cu,d and M ju Then, the following method is used to determine whether the existing structure meets the requirements of "strong nodes and weak components" and to determine whether the nodes need to be reinforced:

[0072] (1) Calculate the bending bearing capacity of the left beam M according to formulas (1) and (2) respectively. bu,l and the bending bearing capacity of the right beam M bu,r Calculate the bending failure of the left beam and the right beam at the dangerous section, that is, the bending strength is M bu,l 、M bu,r hour, j M bu,l is the bending moment at the node center corresponding to the left beam and j M bu,r Bending moment at the center of the node corresponding to the right beam;

[0073]

[0074]

[0075] Where: l b is the length of the beam, l b / 2 is the length of the half-length beam, l c is the height of the column, l c / 2 is the height of the half-height column, h b is the beam section height, h b / 2 is the half-section height of the beam;

[0076] (2) Calculate the bending bearing capacity of the upper column M according to formulas (3) and (4) respectively. cu,t , lower column bending bearing capacity M cu,d Calculate when the upper column and lower column produce bending failure at the dangerous section, that is, reach the bending strength M cu,t 、M cu,dWhen the bending moment at the node center of the upper column is j M cu,t And the bending moment at the node center corresponding to the lower column j M cu,d ;

[0077]

[0078]

[0079] (3) Comparison j M bu,l + j M bu,r , j M cu,t + j M cu,d and M ju The size of the structure is used to determine the failure mode of the structure:

[0080] ① If j M bu,l + j M bu,r Minimum, the failure mode of the structure is beam bending failure, which is an ideal failure mode and does not require reinforcement;

[0081] ②If j M cu,t + j M cu,d Minimum, the failure mode of the structure is column bending failure, and the column needs to be seismically reinforced;

[0082] ③If M ju At the minimum, the failure mode of the structure is node failure, which does not meet the requirements of the seismic code for "strong nodes and weak components" and requires seismic reinforcement of the nodes.

[0083] The purpose of the present invention is to propose a design method for reinforcing beam-column joints by adding wing walls. The reinforcement design method is further described below in the case where the joints need to be reinforced.

[0084] 2. Calculation method of reinforcement requirements

[0085] For structures that require seismic reinforcement at the nodes determined in the first step above, the required reinforcement amount is calculated according to formula (5), with the goal of ensuring that the bending strength of the nodes is greater than the bending strength of the beams.

[0086] M 需 =( j M bu,l + j M bu,r )-M ju (5)

[0087] 3. Method for determining wing wall parameters

[0088] The reinforcement requirement M calculated in the second step above is obtained 需 , provided by the additional wing walls. Figure 3 The mid-node 4 within the dotted line range is reinforced by adding wing walls 6 to form Figure 5 The reinforced structure shown.

[0089] 1) Force of wing wall on beam

[0090] Under the action of earthquake force, the beams and columns at the middle nodes after reinforcement produce Figure 6 The shear force shown; the left beam is under shear force V b,l Under the action of the force, an upward bending deformation occurs, and at this time, a pressure C is generated in the added upper column wing wall. w , a tensile force T is generated in the lower column wing wall w , acting on the beam to limit its bending deformation.

[0091] 2) Conditions for meeting reinforcement requirements

[0092] Pressure C w Generated by the wing wall concrete, the tension T w The pressure C is generated by the anchor bars between the wing wall and the beam. w With tension T w In comparison, the anchor tension T w is small and can be ignored. Therefore, the force distribution around the node area is as follows: Figure 7 Assume that the pressure C w The distance to the node center O is l cw , then C w The moment about point O is C w ·l cw Torque C w ·l cw and the bending bearing capacity of the node M ju The direction of action is consistent, that is, after adding the wing wall, the pressure C w Improved the bending bearing capacity of the node by C w ·l cw If the node's lift C w ·l cw If it is greater than the demand shown in the above formula (5), that is, it satisfies the formula (6), then the reinforcement requirements can be met.

[0093] C w ·l cw >M needs (6)

[0094] 3) Method for determining wing wall parameters

[0095] like Figure 8As shown in the figure, the wing wall parameters that need to be determined during the reinforcement design include: the amount of column anchor bars 7, the amount of beam anchor bars 8, the amount of wing wall longitudinal bars 9, the amount of wing wall transverse bars 10, the concrete strength f c , thickness b w , length l w .

[0096] The amount of column anchor bars 7 and beam anchor bars 8 is determined according to the structural requirements of anchor bars in the specification. The total cross-sectional area of ​​the wing wall longitudinal bars is configured to be larger than the total cross-sectional area of ​​the beam anchor bars, and the total cross-sectional area of ​​the wing wall transverse bars is configured to be larger than the total cross-sectional area of ​​the column anchor bars. c Take a concrete strength value greater than the original structure, and the wing wall thickness b w Take less than the column width b c The integer value of .

[0097] Wing wall length l w The method of determining is as follows: The goal of reinforcement is to form a beam bending failure mechanism in the reinforced structure. After adding wing walls, the cross section of the column changes from square to T-shaped, such as Figure 9 As shown. The bending moment M of the upper column at the dangerous section c,t Under the action of the longitudinal reinforcement in the existing column, the concrete on the wing wall side is under compression. When the T-shaped section reaches full plasticity, the pressure C w According to the force balance, we can obtain the formula (7) and (8), that is, the resultant force of the concrete compressive stress is equal to the resultant force of the steel bar tensile stress.

[0098] C w =T y (7)

[0099] T y =f y ·A s (8)

[0100] Where, T y is the total yield tension of the main reinforcement in the column, f y is the yield strength of the mixed steel bar, which is determined according to the type of steel bar; A s is the total cross-sectional area of ​​the main reinforcement in the column.

[0101] The height x of the concrete compression zone is calculated according to formula (9).

[0102]

[0103] Where, α is the equivalent rectangular stress diagram coefficient of the concrete compression zone, f c It is the design value of concrete compressive strength, which is determined according to the specification based on the design value of concrete strength.

[0104] Wing wall pressure C w The distance l to the node center ocw Calculated according to formula (10).

[0105]

[0106] Combining formula (10) with formulas (5), (6), (7), and (8) yields formula (11).

[0107]

[0108] From formula (11), we can get the wing wall length l w Should meet the following requirements:

[0109]

[0110] According to the above method, all the parameters of the wing wall can be determined: the amount of column anchor bars, the amount of beam anchor bars, the amount of wing wall longitudinal bars, the amount of wing wall transverse bars, concrete strength, wing wall thickness, and wing wall length.

[0111] It should be noted that the terms "left", "right", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or that are inherent to these processes, methods, products or devices.

[0112] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0113] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A design method for reinforcing the intermediate joints of reinforced concrete frame beams and columns by adding wing walls, characterized in that: include, S1, when bending failure occurs at the dangerous section, the bending moment at the node center of the left beam is obtained by calculation. j M bu,l , the bending moment at the node center corresponding to the right beam j M bu,r , the bending moment at the center of the node corresponding to the upper column j M cu,t And the bending moment at the node center corresponding to the lower column j M cu,d , determine the failure mode of the reinforced concrete frame and whether it needs seismic reinforcement. If it is determined that the node needs seismic reinforcement, proceed to S2; S2, with the goal of making the bending strength of the node greater than the bending strength of the beam, calculates the required reinforcement of the node; S3, determine the parameters of adding wing walls based on the reinforcement requirements of the nodes, thereby strengthening the middle nodes of reinforced concrete frame beams and columns; The calculation formula for the reinforcement requirement of the node is: M 需 =( j M bu,l + j M bu,r )-M ju (5) Where: M 需 To strengthen the demand, jM bu,l is the bending moment at the node center corresponding to the left beam, j M bu,r is the bending moment at the node center of the right beam, M ju is the node bending capacity; The conditions for the reinforcement requirements of the additional wing wall are as follows: Cw·lcw>M need (6) Where: C w To generate pressure in the additional upper column wing wall; cw The pressure C generated in the added upper column wing wall w Distance to the node center; C w ·l cw The pressure C generated in the added upper column wing wall w Moment about the nodal center; The parameters of the wing wall include the amount of column anchor bars, the amount of beam anchor bars, the amount of wing wall longitudinal bars, the amount of wing wall transverse bars, the concrete compressive strength f c , Wing wall thickness b w and wing wall length l w ; The amount of column anchor bars and beam anchor bars is determined according to the structural requirements of anchor bars in industry specifications. The amount of wing wall longitudinal bars is configured based on the total cross-sectional area of ​​the wing wall longitudinal bars being larger than the total cross-sectional area of ​​the beam anchor bars. The amount of wing wall transverse bars is configured based on the total cross-sectional area of ​​the wing wall transverse bars being larger than the total cross-sectional area of ​​the column anchor bars. The concrete compressive strength f c Take a value greater than the concrete strength of the original structure, the wing wall thickness b w Take less than the column width b c The integer value of .

2. The design method for reinforcing the intermediate nodes of reinforced concrete frame beams and columns by adding wing walls according to claim 1 is characterized in that: The specific process of S1 is as follows: According to the cross-sectional dimensions, reinforcement and material strength of the reinforced concrete frame components, the bending bearing capacity of the left beam M is calculated. bu,l , right beam bending bearing capacity M bu,r , Upper column bending bearing capacity M cu,t , lower column bending bearing capacity M cu,d and the node bending capacity M ju , and then calculate the bending moment at the node center of the left beam when bending failure occurs at the dangerous section j M bu,l , the bending moment at the node center corresponding to the right beam j M bu,r , the bending moment at the center of the node corresponding to the upper column j M cu,t And the bending moment at the node center corresponding to the lower column j M cu,d ; contrast j M bu,l + j M bu,r , jM cu,t + j M cu,d and M ju The size of the reinforced concrete frame is used to determine the failure mode of the reinforced concrete frame; like j M bu,l + j M bu,r At the minimum, the failure mode of reinforced concrete frame is beam bending failure, which is an ideal failure mode and does not require reinforcement; like j M cu,t + j M cu,d At the minimum, the failure mode of reinforced concrete frames is column bending failure, which requires seismic reinforcement of the columns; If M ju At the very least, the failure mode of the reinforced concrete frame is node failure, which does not meet the requirements of strong nodes and weak components in the seismic code, so the nodes need to be seismically reinforced.

3. The design method for reinforcing the intermediate nodes of reinforced concrete frame beams and columns by adding wing walls according to claim 1, characterized in that: The bending moment at the center of the node corresponding to the left beam j M bu,l The calculation process is: Where: M bu,l is the bending bearing capacity of the left beam, l b is the length of the beam, l b / 2 is the length of the half-length beam, h c is the column section width, h c / 2 is the half-section width of the column.

4. The design method for reinforcing the intermediate nodes of reinforced concrete frame beams and columns by adding wing walls according to claim 1, characterized in that: The bending moment at the center of the node corresponding to the right beam j M bu,r The calculation process is: Where: M bu,r is the bending capacity of the right beam, l b is the length of the beam, l b / 2 is the length of the half-length beam, h c is the column section width, h c / 2 is the half-section width of the column.

5. The design method for reinforcing the intermediate nodes of reinforced concrete frame beams and columns by adding wing walls according to claim 1, characterized in that: The bending moment at the center of the node corresponding to the upper column j M cu,t The calculation process is: Where: M cu,t is the bending bearing capacity of the upper column, l c is the height of the column, l c / 2 is the height of the half-height column, h b is the beam section height, h b / 2 is the half-section height of the beam.

6. The design method for reinforcing the intermediate nodes of reinforced concrete frame beams and columns by adding wing walls according to claim 1, characterized in that: The bending moment at the node center corresponding to the lower column j M cu,d The calculation process is: Where: M cu,d is the bending bearing capacity of the lower column, l c is the height of the column, l c / 2 is the height of the half-height column, h b is the beam section height, h b / 2 is the half-section height of the beam.

7. The design method for reinforcing the intermediate nodes of reinforced concrete frame beams and columns by adding wing walls according to claim 1, characterized in that: The wing wall length l w The method for determining is: After adding wing walls to the reinforced concrete frame, the cross section of the column changes from square to T-shaped. When the T-shaped cross section reaches full plasticity, a pressure C is generated in the added upper column wing wall. w According to the force balance, we can obtain the formula (7) and (8), that is, the resultant force of the concrete compressive stress is equal to the resultant force of the steel bar tensile stress; C w =T y (7) T y =f y ·A s (8) Where, T y is the total yield tension of the main reinforcement in the column, f y is the yield strength of the steel bar; A s is the total cross-sectional area of ​​the main reinforcement in the column; The height x of the concrete compression zone is obtained according to formula (9); Where, α is the equivalent rectangular stress diagram coefficient of the concrete compression zone, f c is the compressive strength of concrete; The pressure C generated in the added upper column wing wall w The distance to the node center l cw , obtained according to formula (10); Where: h c is the column section width, h c / 2 is the half-section width of the column; x is the height of the concrete compression zone, l w is the wing wall length; Combining formula (10) with formulas (5), (6), (7), and (8), we can obtain formula (11); From formula (11), we can get the wing wall length l w Should meet the following requirements: Where: jM bu,l is the bending moment at the node center corresponding to the left beam, j M bu,r is the bending moment at the node center of the right beam, M ju is the node bending capacity, b w is the wing wall thickness, f c is the design value of concrete compressive strength, α is the equivalent rectangular stress diagram coefficient of concrete compression zone, A s is the total cross-sectional area of ​​the main reinforcement in the column, h c / 2 is the half-section width of the column, f y is the yield strength of the steel bar.

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