Reinforced concrete frame column reinforced with steel sleeve and construction method thereof

Abstract

The application discloses a reinforced concrete frame column reinforced by a steel sleeve and a construction method thereof, which comprises a reinforced concrete column, a cross beam and a floor slab, the reinforced concrete column is vertically arranged between the cross beam and the floor slab, a steel plate is attached to each column surface of the reinforced concrete column, two adjacent steel plates are connected through connecting angle steels, and a steel sleeve is formed to surround the reinforced concrete column; end portion angle steels are welded to both ends of the steel plate, and the end portion angle steels at both ends of the steel plate are connected to the reinforced concrete beam and the floor slab through anchoring bolts respectively. The application can directly reinforce the reinforced concrete column, and the operation is simple and the construction speed is fast.

Description

Technical Field

[0001] This invention relates to the field of building structure reinforcement technology, and in particular to a reinforced concrete frame column reinforced with a steel sleeve and its construction method. Background Technology

[0002] For existing reinforced concrete frame structures with large stock, construction defects, changes in functionality, and exposure to earthquakes and fires can all lead to structural collapse, posing a threat to people's lives and property. Therefore, reinforcement techniques are needed to enhance structural safety. However, most existing reinforcement methods involve wet work environments or welding, making construction complex and hindering rapid reinforcement. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a reinforced concrete frame column reinforced with steel sleeve and its construction method. The reinforced concrete frame column reinforced with steel sleeve and its construction method are simple to operate, fast to construct, and do not require a wet working environment or on-site welding.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A reinforced concrete frame column reinforced with a steel sleeve includes a reinforced concrete column and a steel sleeve. The reinforced concrete column is vertically positioned between the beam and the floor slab, and the cross-section of the reinforced concrete column is rectangular. The steel sleeve includes four steel plates, connecting angle steel, and end angle steel. The four steel plates are attached to the four side walls of the reinforced concrete column; adjacent steel plates are connected by several equally spaced connecting angle steel; the top and bottom ends of each steel plate are connected to the beam or floor slab through end angle steel.

[0006] Furthermore, the width of the steel plate is 5cm less than the width of the contact surface with the reinforced concrete column, and the length of the steel plate is 10cm less than the height of the contact surface with the reinforced concrete column.

[0007] Furthermore, the end angle steel is provided with triangular steel ribs perpendicular to the cross-section of the end angle steel.

[0008] Furthermore, mortar is used to fill the space between the end angle steel and the floor slab, as well as between the end angle steel and the beam.

[0009] Furthermore, let the thickness of each steel plate be t. p The spacing between the connecting angle steels that connect two adjacent steel plates is s. d , then t p and s d It is necessary to determine the bearing capacity V of the reinforced concrete column before reinforcement. capAnd the horizontal external load V and the bearing capacity V after reinforcement stren and V cap,stren To be confirmed.

[0010] Furthermore, t p and s d The specific method for determining it includes the following steps:

[0011] Step 1: Determine the bearing capacity V of the reinforced concrete column before reinforcement. cap .

[0012] Step 2, calculate s d Specifically, the calculation formulas are as follows:

[0013] Step 2-1, s d The expression for: the shear strength V of the reinforced concrete column after strengthening. stren Expressed as about s d Functions:

[0014]

[0015] In the formula, V d V c and V s These represent the shear strength of the steel sleeve, the concrete in the reinforced concrete column, and the stirrups in the reinforced concrete column, respectively.

[0016] d c and d w These are the total cross-sectional length and the effective cross-sectional length of the reinforced concrete column, respectively.

[0017] F d To determine the shear strength of the connecting angle steel, the value is related to the steel plate thickness t. p The function.

[0018] N0 is the total external load along the axial direction of the reinforced concrete column, which is known.

[0019] A c and A st These are the cross-sectional areas of the reinforced concrete column and the stirrups, respectively.

[0020] f c ′ and f yst These are the concrete compressive strength and the stirrup tensile strength, both of which are known quantities;

[0021] s st The spacing of the stirrups in the reinforced concrete column is a known quantity.

[0022] γ s and γ c These are the safety factors for steel and concrete, respectively, both of which are known quantities;

[0023] m represents the number of stirrup legs or longitudinal reinforcement rows in a reinforced concrete column.

[0024] Step 2-2, Calculate s dmax With V≤0.6V stren s was calculated d Maximum upper limit value s dmax Where V is the total external horizontal load borne by the reinforced concrete column, which is a known or calculated value.

[0025] Steps 2-3: Calculate s dmin s dmin Regarding the thickness t of the steel plate p The function is specifically calculated using the following formula:

[0026] V cap,stren ≤0.6V stren

[0027] In the formula, V cap,stren Regarding the thickness t of the steel plate p The function.

[0028] Step 3: Determine the initial value t of the steel plate thickness. p0 Specifically, it includes the following steps:

[0029] Step 3-1, Establish η M -t p Linear relationship curve: through theoretical analysis (η) M =V cap,stren / V cap ), to obtain η M -t p Linear relationship curve.

[0030] Step 3-2: Solve for the actual η M The specific formula for solving this problem is as follows:

[0031] η M =V / V cap

[0032] Step 3-3: Determine the initial value t of the steel plate thickness. p0 : Solve for η in step 3-2 M Substitute η from step 3-1 M -t p From the linear relationship curve, the initial value t of the steel plate thickness can be obtained. p0 .

[0033] Step 4: Determine the optimal steel plate thickness t p Optimal steel plate thickness t p The following three constraints must be met simultaneously:

[0034] Constraint 1, V cap,stren ≥V;

[0035] Constraint condition 2: ALR ≤ 0.65; where ALR is the axial compression ratio of the reinforced concrete column, which is a function of t. p The function.

[0036] Constraint 3: The flexural stiffness of the reinforced concrete column after reinforcement is matched with that of the unreinforced reinforced concrete column.

[0037] The initial value t of the steel plate thickness determined in step 3. p0 Substituting these three constraints into the above three conditions, when t p0 When all three constraints are met, then t p0 That is, the determined optimal steel plate thickness t p Otherwise, with t p0 Starting from t, increase t p When t increases p When all three constraints are met, then t at this time p That is, the determined optimal steel plate thickness t p .

[0038] Step 5: Calculate s dmin The optimal steel plate thickness t determined in step 4 p Substituting into steps 2-3, we obtain s. dmin .

[0039] Furthermore, in steps 2-3, V cap,stren The expression is:

[0040]

[0041] Among them, M cap,stren The expression for the strengthening bending moment of a reinforced concrete column is:

[0042]

[0043] Where, x c The height of the compression zone of the reinforced concrete column is obtained by solving the following expression:

[0044]

[0045] In the formula, α and β are known constants.

[0046] k j Let be the number of longitudinal bars in the j-th row of stirrups; where 1≤j≤m;

[0047] A l and A pThese are the cross-sectional areas of the longitudinal reinforcement and the cross-sectional area of ​​the steel plate, respectively.

[0048] σ lj σ pt1 σ pc1 and σ pside_i These are the longitudinal reinforcement stress, the tensile side plate stress, the tension side plate stress, and the i-th portion of the plate stress, all of which are related to the plate thickness t. p The function.

[0049] c represents the thickness of the protective layer in the reinforced concrete column.

[0050] φ st and φ l These refer to the diameters of the stirrups and longitudinal bars, respectively.

[0051] s l This refers to the spacing between the longitudinal reinforcement bars.

[0052] Δ i Let be the length of the i-th equal part of the steel plate, which is a known quantity; 1≤i≤n; n is the total number of equal parts into which the steel plate is divided.

[0053] d p This is the length of the steel plate's cross-section.

[0054] Furthermore, in step 4, the formula for calculating ALR is:

[0055]

[0056] Where, N c,stren The axial bearing capacity of the reinforced concrete column after reinforcement is obtained using the following formula:

[0057]

[0058] In the formula, A c This represents the cross-sectional area of ​​the concrete column.

[0059] f c ′ represents the compressive strength of concrete.

[0060] f yl Let be the yield strength of the longitudinal reinforcement, and be a known quantity.

[0061] σ p,critical For the stress in the steel plate, and for t p The function.

[0062] Furthermore, in constraint condition three of step 4, let the bending stiffness of the reinforced concrete column after reinforcement be K. i K i The calculation formula is as follows:

[0063] K i =(EI)s +α c (EI) c

[0064] Among them, (EI) s For the bending strength of the steel casing, for t p The function.

[0065] α c It is a known constant.

[0066] (EI) c The flexural strength of the concrete itself is a known quantity.

[0067] A construction method for reinforced concrete frame columns reinforced with steel sleeves includes the following steps.

[0068] Step 1: Prefabricated steel sleeve: The steel sleeve consists of four steel plates, connecting angle steel, and end angle steel; wherein, the thickness of each steel plate is t. p , and t p It is necessary to determine the bearing capacity V of the reinforced concrete column before reinforcement. cap and the reinforced bearing capacity V cap,stren To be confirmed.

[0069] Step 2, attaching steel plates: attach the four prefabricated steel plates from Step 1 to the four surfaces of the reinforced concrete column.

[0070] Step 3, Vertical connection of steel plates: Connect the top of each steel plate to the crossbeam through end angle steel; connect the bottom of each steel plate to the floor slab through end angle steel.

[0071] Step 4, Lateral connection of steel plates: Connect adjacent steel plates using several equally spaced connecting angle steels; the spacing s of the connecting angle steels d It is necessary to consider the horizontal external load V on the reinforced concrete column and the shear bearing capacity V after reinforcement. stren The process is as follows: four steel plates, connecting angle steel, and end angle steel together form a steel sleeve, which surrounds the reinforced concrete column, thus completing the reinforcement of the reinforced concrete frame column.

[0072] By employing the above technical solutions, the present invention has the following beneficial effects compared to the prior art:

[0073] This invention directly reinforces reinforced concrete columns by placing steel plates in contact with them and connecting the two ends of the steel plates to beams and floor slabs using end angle steel. At the same time, the steel plates are connected by connecting angle steel to form a steel sleeve that surrounds the reinforced concrete column. This method allows for direct reinforcement of reinforced concrete columns and is simple to operate and quick to construct. Attached Figure Description

[0074] Figure 1This is a front view of a reinforced concrete frame column reinforced with a steel sleeve according to the present invention.

[0075] Figure 2 This is a cross-sectional schematic diagram of the connection between the steel sleeve and the beam or floor slab according to an embodiment of the present invention.

[0076] Figure 3 This is a cross-sectional schematic diagram of a steel sleeve surrounding a reinforced concrete column according to an embodiment of the present invention.

[0077] Figure 4 This is a flowchart illustrating the process of determining node spacing.

[0078] Figure 5 η is when ALR = 0.15 M -t p Linear relationship curve.

[0079] Figure 6 η is when ALR = 0.3 M -t p Linear relationship curve.

[0080] The components include: 1. reinforced concrete column, 2. beam, 3. floor slab, 4. steel plate, 5. connecting angle steel, 6. steel sleeve, 7. end angle steel, 8. anchor bolt, 9. triangular steel rib plate, and 10. rivet. Detailed Implementation

[0081] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0082] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0083] like Figures 1 to 3 As shown, a reinforced concrete frame column reinforced with a steel sleeve includes reinforced concrete 1 and a steel sleeve 6.

[0084] The reinforced concrete column 1 is vertically positioned between the beam 2 and the floor slab 3, and the cross section of the reinforced concrete column 1 is rectangular.

[0085] The steel sleeve 6 includes four steel plates 4, connecting angle steel 5, and end angle steel 7.

[0086] Four steel plates 4 are attached to the four side walls of the reinforced concrete column 1; adjacent steel plates 4 are connected by several equally spaced connecting angle steels 5; the top and bottom of each steel plate 4 are connected to the beam 2 or floor slab 3 by end angle steels 7.

[0087] The width of the steel plate 4 is 5cm less than the width of the contact surface with the reinforced concrete column 1, and the length of the steel plate 4 is 10cm less than the height of the contact surface with the reinforced concrete column 1.

[0088] Furthermore, the end angle steel 7 is preferably provided with a triangular steel rib 9 that is perpendicular to the cross section of the end angle steel 7.

[0089] Mortar is used to fill the space between the end angle steel 7 and the floor slab 3, as well as between the end angle steel 7 and the beam 2.

[0090] A construction method for reinforced concrete frame columns reinforced with steel sleeves includes the following steps.

[0091] Step 1, Prefabricated steel sleeve 6: It is preferable to pre-weld end angle steel 7 at both ends of each steel plate 4 in the factory to avoid on-site welding.

[0092] Step 2, attaching steel plates 4: attach the four steel plates 4 prefabricated in Step 1 to the four column surfaces of the reinforced concrete column 1.

[0093] Step 3, Vertical connection of steel plates 4: Connect the top of each steel plate 4 to the crossbeam 2 via end angle steel 7; connect the bottom of each steel plate 4 to the floor slab 3 via end angle steel 7. The preferred connection method between the end angle steel 7 and the floor slab 3 or crossbeam 2 is to use anchor bolts 8.

[0094] Step 4, Lateral connection of steel plates 4: Connect two adjacent steel plates 4 with several equally spaced connecting angle steels 5. When connecting two steel plates 4 using connecting angle steels 5, high-strength rivets 10 can be driven into the connecting angle steels 5 and steel plates 4 using a gunpowder gun to fix them together.

[0095] Assume that the thickness of each steel plate 4 is t. p The spacing between the connecting angle steels 5 that connect two adjacent steel plates 4 is s. d , then t p and s d The bearing capacity V of reinforced concrete column 1 before reinforcement needs to be considered. cap And the horizontal external load V and the bearing capacity V after reinforcement stren and V cap,stren To be confirmed.

[0096] The above t p and s d The specific method for determining it, such as Figure 4 As shown, the preferred method includes the following steps:

[0097] Step 1: Determine the bearing capacity V of reinforced concrete column 1 before reinforcement. cap The method used to determine this is existing technology and will not be elaborated here.

[0098] Step 2, calculate s d Specifically, the calculation formulas are as follows:

[0099] Step 2-1, s d The expression for: the shear strength V of the reinforced concrete column after strengthening. stren Expressed as about s d Functions:

[0100]

[0101] In the formula, V d V c and V s These represent the shear strength of the steel sleeve, the concrete in the reinforced concrete column, and the stirrups in the reinforced concrete column, respectively.

[0102] d c and d w These are the cross-sectional length and effective cross-sectional length of the reinforced concrete column, respectively.

[0103] N0 is the total external load along the axial direction of the reinforced concrete column, which is known.

[0104] A c and A st These are the cross-sectional areas of the reinforced concrete column and the stirrups, respectively.

[0105] f c ′ and f yst These are the concrete compressive strength and the stirrup tensile strength, respectively, both of which are known quantities.

[0106] s st The spacing of the stirrups in the reinforced concrete column is a known quantity.

[0107] γ s and γ c These are the safety factors for steel and concrete, respectively, both of which are known quantities.

[0108] m represents the number of stirrup legs or longitudinal reinforcement rows in a reinforced concrete column.

[0109] The above F d The preferred calculation formula for the shear strength of connecting angle steel is:

[0110] F d =ψ fp ψ fk α br dn t p f up

[0111] In the formula, ψ fp The influence factor for the protrusion of the connecting angle steel is 1.35 when the steel plate has no rivet pre-drilled holes, otherwise it is 1.0.

[0112] ψ fk The rivet pattern influence factor is 1.17 when the rivet surface has a pattern, and 1.0 otherwise.

[0113] α br Given a constant, the preferred value is 1.6.

[0114] d n This refers to the diameter of the rivet.

[0115] f up Given the strength of the connecting angle steel, the quantity is known.

[0116] Step 2-2, Calculate s dmax With V≤0.6V stren s was calculated d Maximum upper limit value s dmax Where V is the total external horizontal load borne by the reinforced concrete column, which is a known or calculated value.

[0117] Steps 2-3: Calculate s dmin s dmin Regarding the thickness t of the steel plate p The function is specifically calculated using the following formula:

[0118] V cap,stren ≤0.6V stren

[0119] In the formula, V cap,stren Regarding the thickness t of the steel plate p The function.

[0120] Step 3: Determine the initial value t of the steel plate thickness. p0 Specifically, it includes the following steps.

[0121] Step 3-1, Establish η M -t p Linear relationship curve: η is obtained through theoretical analysis. M -t p Linear relationship curves, such as Figure 5 and Figure 6 As shown, where ρ l Let be the reinforcement ratio of the steel bars, a known quantity.

[0122] The above η M -tp When establishing the linear relationship curve, η M It is calculated using the following formula:

[0123] η M =V cap,stren / V cap

[0124] In the formula, V cap,stren Regarding the thickness t of the steel plate p The preferred expression for the function is:

[0125]

[0126] Where L is the height of the concrete column, M cap,stren The expression for the bending moment of a reinforced concrete column after strengthening is:

[0127]

[0128] Where, x c The height of the compression zone of the reinforced concrete column is obtained by solving the following expression:

[0129]

[0130] In the formula, α and β are known constants, preferably both of which are taken as 0.85.

[0131] k j Let be the number of longitudinal bars in the j-th row of stirrups; where 1≤j≤m.

[0132] A l and A p These are the cross-sectional areas of the longitudinal reinforcement and the cross-sectional area of ​​the steel plate, respectively.

[0133] c represents the thickness of the protective layer in the reinforced concrete column.

[0134] φ st and φ l These refer to the diameters of the stirrups and longitudinal bars, respectively.

[0135] s l This refers to the spacing between the longitudinal reinforcement bars.

[0136] Δ i Let be the length of the i-th equal part of the steel plate, which is a known quantity; 1≤i≤n; n is the total number of equal parts into which the steel plate is divided.

[0137] d p This is the length of the steel plate's cross-section.

[0138] σ lj σ pt1 σ pc1 and σ pside_iThese are the longitudinal reinforcement stress, the tensile side steel plate stress, the compression side steel plate stress, and the i-th equal part of the steel plate stress, respectively.

[0139] The above σ lj σ pt1 σ pc1 and σ pside_i The preferred expression is:

[0140]

[0141]

[0142]

[0143]

[0144] Where, σ p,critical For the stress in the steel plate, and for t p The function, specifically the expression:

[0145]

[0146] α i =1.046-0.0073λ sr

[0147] λ sr =s d / t p

[0148] In the formula, f yl and f py These are the yield strengths of the longitudinal reinforcement and the yield strength of the steel plate, both of which are known quantities.

[0149] E s and E p These are the elastic modulus of the longitudinal reinforcement and the elastic modulus of the steel plate, respectively.

[0150] ε cu Let be the ultimate compressive strain of the concrete, and be a known quantity.

[0151] μ p The steel plate has a Poisson's ratio, which is a known quantity; α i λ is the buckling defect factor of the steel plate. sr The slenderness ratio of the steel plate.

[0152] Step 3-2: Solve for the actual η M The specific formula for solving this problem is as follows:

[0153] η M =V / V cap

[0154] Step 3-3: Determine the initial value t of the steel plate thickness.p0 : Solve for η in step 3-2 M Substitute η from step 3-1 M -t p From the linear relationship curve, the initial value t of the steel plate thickness can be obtained. p0 .

[0155] Step 4: Determine the optimal steel plate thickness t p Optimal steel plate thickness t p The following three constraints must be met simultaneously:

[0156] Constraint 1, V cap,stren ≥V;

[0157] Constraint condition 2: ALR ≤ 0.65; where ALR is the axial compression ratio of the reinforced concrete column, which is a function of t. p The function, specifically the expression:

[0158]

[0159] Where, N c,stren The axial bearing capacity of the reinforced concrete column after reinforcement is obtained using the following formula:

[0160]

[0161] In the formula, A c Cross-sectional area of ​​concrete column;

[0162] f yl The yield strength of the longitudinal reinforcement;

[0163] d l To reinforce the length of the concrete column without joint coverage;

[0164] σ p,critical For the compressive stress of the steel plate, let be the stress about t. p The function.

[0165] Constraint 3: The flexural stiffness of the reinforced concrete column after reinforcement is matched with that of the unreinforced reinforced concrete column.

[0166] The initial value t of the steel plate thickness determined in step 3. p0 Substituting these three constraints into the above three conditions, when t p0 When all three constraints are met, then t p0 That is, the determined optimal steel plate thickness t p Otherwise, with t p0 Starting from t, increase t p When t increases p When all three constraints are met, then t at this time pThat is, the determined optimal steel plate thickness t p .

[0167] In constraint condition three of step 4, let the bending stiffness of the reinforced concrete column after reinforcement be K. i K i The calculation formula is as follows:

[0168]

[0169] Among them, (EI) s For the bending strength of the steel casing, for t p The function.

[0170] α c Given a constant, 0.6 is preferred; E c The elastic modulus of concrete is a known quantity.

[0171] (EI) c The flexural strength of the concrete itself is a known quantity.

[0172] Step 5: Calculate s dmin The optimal steel plate thickness t determined in step 4 p Substituting into steps 2-3, we obtain s. dmin ; Spacing s of connecting angle steel d (also known as node spacing s) d ), as needed in s dmin and s dmax You can take any value between these ranges.

[0173] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0174] The meaning of "and / or" as used in this application includes situations where each exists alone or both exist simultaneously.

[0175] The term "connection" as used in this application can mean a direct connection between components or an indirect connection between components through other components.

[0176] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A reinforced concrete frame column reinforced with a steel sleeve, characterized in that: Including reinforced concrete columns and steel sleeves; The reinforced concrete column is vertically installed between the beam and the floor slab, and the cross-section of the reinforced concrete column is rectangular; the steel sleeve includes four steel plates, connecting angle steel and end angle steel; the four steel plates are attached to the four side walls of the reinforced concrete column; adjacent steel plates are connected by several equally spaced connecting angle steels; the top and bottom of each steel plate are connected to the beam or floor slab through end angle steels; Assume the thickness of each steel plate is t. p The spacing between the connecting angle steels that connect two adjacent steel plates is s. d , then t p and s d It is necessary to determine the bearing capacity V of the reinforced concrete column before reinforcement. cap and the reinforced bearing capacity V stren and V cap,stren To confirm; t p and s d The specific method for determining it includes the following steps: Step 1: Determine the bearing capacity V of the reinforced concrete column before reinforcement. cap ; Step 2, calculate s d Specifically, the calculation formulas are as follows: Step 2-1, s d The expression for: the shear strength V of the reinforced concrete column after strengthening. stren Expressed as about s d Functions: In the formula, V d V c and V s These are the shear strengths of the steel sleeve, the concrete in the reinforced concrete column, and the stirrups in the reinforced concrete column, respectively. d c and d w These are the total cross-sectional length and the effective cross-sectional length of the reinforced concrete column, respectively. F d To determine the shear strength of the connecting angle steel, the value is related to the steel plate thickness t. p The function; N0 is the total external load along the axis of the reinforced concrete column, which is known. A c and A st These are the cross-sectional areas of the reinforced concrete column and the stirrups, respectively. f c ′ and f yst These are the concrete compressive strength and the stirrup tensile strength, both of which are known quantities; s st The spacing of the stirrups in the reinforced concrete column is a known quantity. γ s and γ c These are the safety factors for steel and concrete, respectively, both of which are known quantities; m represents the number of stirrup legs or longitudinal reinforcement rows in a reinforced concrete column; Step 2-2, Calculate s dmax With V≤0.6V stren s was calculated d Maximum upper limit value s dmax Where V is the total external horizontal load borne by the reinforced concrete column, which is a known or calculated value; Steps 2-3: Calculate s dmin s dmin Regarding the thickness t of the steel plate p The function is specifically calculated using the following formula: V cap,stren ≤0.6V stren In the formula, V cap,stren Regarding the thickness t of the steel plate p The function; Step 3: Determine the initial value t of the steel plate thickness. p0 Specifically, it includes the following steps: Step 3-1, Establish η M -t p Linear relationship curve: through theoretical analysis (η) M =V cap,stren / V cap ), to obtain η M -t p Linear relationship curve; Step 3-2: Solve for the actual η M The specific formula for solving this problem is as follows: η M =V / V cap Step 3-3: Determine the initial value t of the steel plate thickness. p0 : Solve for η in step 3-2 M Substitute η from step 3-1 M -t p From the linear relationship curve, the initial value t of the steel plate thickness can be obtained. p0 ; Step 4: Determine the optimal steel plate thickness t p Optimal steel plate thickness t p The following three constraints must be met simultaneously: Constraint 1, V cap,stren ≥V; Constraint condition 2: ALR ≤ 0.65; where ALR is the axial compression ratio of the reinforced concrete column, which is a function of t. p The function; Constraint condition 3: The flexural stiffness of the reinforced concrete column after reinforcement must match the flexural stiffness of the unreinforced reinforced concrete column; the initial value t of the steel plate thickness determined in step 3 must be used. p0 Substituting these three constraints into the above three conditions, when t p0 When all three constraints are met, then t p0 That is, the determined optimal steel plate thickness t p Otherwise, with t p0 Starting from t, increase t p When t increases p When all three constraints are met, then t at this time p That is, the determined optimal steel plate thickness t p ; Step 5: Calculate s dmin The optimal steel plate thickness t determined in step 4 p Substituting into steps 2-3, we obtain s. dmin .

2. The reinforced concrete frame column reinforced with a steel sleeve according to claim 1, characterized in that: The width of the steel plate is less than 5cm of the width of the contact surface with the reinforced concrete column, and the length of the steel plate is less than 10cm of the height of the contact surface with the reinforced concrete column.

3. The reinforced concrete frame column reinforced with a steel sleeve according to claim 1, characterized in that: The end angle steel is provided with a triangular steel rib plate that is perpendicular to the cross section of the end angle steel.

4. The reinforced concrete frame column reinforced with a steel sleeve according to claim 1, characterized in that: Mortar is used to fill the space between the end angle steel and the floor slab, as well as between the end angle steel and the beam.

5. The reinforced concrete frame column reinforced with a steel sleeve according to claim 1, characterized in that: In steps 2-3, V cap,stren The expression is: Among them, M cap,stren The expression for the strengthening bending moment of a reinforced concrete column is: Where, x c The height of the compression zone of the reinforced concrete column is obtained by solving the following expression: In the formula, α and β are known constants; k j Let be the number of longitudinal bars in the j-th row of stirrups; where 1≤j≤m; A l and A p These are the cross-sectional areas of the longitudinal reinforcement and the cross-sectional area of ​​the steel plate, respectively. σ lj σ pt1 σ pc1 and σ pside_i These are the longitudinal reinforcement stress, the tensile side plate stress, the tension side plate stress, and the i-th portion of the plate stress, all of which are related to the plate thickness t. p The function; c represents the thickness of the protective layer in the reinforced concrete column; φ st and φ l These are the diameters of the stirrups and longitudinal bars, respectively. s l This refers to the spacing between longitudinal reinforcement bars; Δ i Let be the length of the i-th equal part of the steel plate, a known quantity; 1≤i≤n; n is the total number of equally spaced parts of the steel plate. d p This is the length of the steel plate's cross-section.

6. The reinforced concrete frame column reinforced with a steel sleeve according to claim 1, characterized in that: In step 4, the formula for calculating ALR is: Where, N c,stren The axial bearing capacity of the reinforced concrete column after reinforcement is obtained using the following formula: In the formula, A c The cross-sectional area of ​​the concrete column; f c ′ represents the compressive strength of concrete; f yl σ is the yield strength of the longitudinal reinforcement, which is a known quantity; p,critical For the stress in the steel plate, and for t p The function.

7. The reinforced concrete frame column reinforced with a steel sleeve according to claim 1, characterized in that: In constraint condition three of step 4, let the bending stiffness of the reinforced concrete column after reinforcement be K. i K i The calculation formula is as follows: K i =(NO) s +α c (NO) c Among them, (EI) s For the bending strength of the steel casing, for t p The function of α; c It is a known constant; (EI) c The flexural strength of the concrete itself is a known quantity.

8. A construction method for reinforced concrete frame columns reinforced with steel sleeves: characterized in that: Includes the following steps: Step 1: Prefabricated steel sleeve: The steel sleeve consists of four steel plates, connecting angle steel, and end angle steel; wherein, the thickness of each steel plate is t. p , and t p It is necessary to determine the bearing capacity V of the reinforced concrete column before reinforcement. cap and the reinforced bearing capacity V cap,stren To confirm; Step 2, attaching steel plates: attach the four prefabricated steel plates from Step 1 to the four surfaces of the reinforced concrete column; Step 3, Vertical connection of steel plates: Connect the top of each steel plate to the crossbeam using end angle steel; connect the bottom of each steel plate to the floor slab using end angle steel. Step 4, Lateral connection of steel plates: Connect adjacent steel plates using several equally spaced connecting angle steels; the spacing s of the connecting angle steels d It is necessary to consider the horizontal external load V on the reinforced concrete column and the shear bearing capacity V after reinforcement. stren The process is as follows: four steel plates, connecting angle steel, and end angle steel together form a steel sleeve, which surrounds the reinforced concrete column, thus completing the reinforcement of the reinforced concrete frame column.

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