A cross-sectional design method for concrete beams for active CO2 storage

Abstract

The present invention proposes for the first time a cross-section design method for concrete beams for active CO2 storage. The method first calculates and obtains the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the cross section. c ; Then according to the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section c , determining whether to design a single-reinforced rectangular cross-section or a double-reinforced rectangular cross-section; based on the determination, performing the single-reinforced or double-reinforced rectangular cross-section design, and verifying the designed single-reinforced or double-reinforced rectangular cross-section. This method fills a gap in the cross-sectional design of hybrid reinforced concrete beams for active CO2 storage, thereby promoting the production and manufacturing of such concrete beams.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete beams, relates to the cross-section design of concrete beams, and particularly relates to a cross-section design method of a concrete beam for actively sequestering CO2. Background Art

[0002] The main components of the concrete pore solution include hydrated calcium silicate, calcium hydroxide, ettringite, and hydrated calcium sulfoaluminate. The concrete pore solution is a highly alkaline mixture with a pH of over 13, making it susceptible to chemical reactions with CO2. Curing cementitious materials with high-concentration CO2 gas allows the CO2 gas to react with cement clinker, forming stable calcium carbonate crystals, enabling permanent CO2 storage. Compared to geological and deep-sea storage, storing CO2 in concrete poses no risk of gas leakage and eliminates the need for real-time monitoring and risk assessment. Furthermore, cementitious materials for active CO2 storage offer excellent mechanical and durability properties and a long service life, thereby reducing energy consumption and carbon emissions in the construction industry. However, while long-term CO2 curing of reinforced concrete structures can achieve large-scale active CO2 storage, it can also lead to durability issues such as steel corrosion.

[0003] Fiber reinforced polymer (FRP) has strong corrosion resistance and can replace steel bars in concrete structures under corrosive environments. - It can induce intrinsic microscopic damage such as debonding of the fiber-matrix interface and destruction of the fiber molecular structure. Therefore, the high alkaline environment in the concrete pore solution is not conducive to the long-term performance of FRP bars.

[0004] Therefore, using a mixed reinforcement of steel and FRP bars to actively store CO2 in concrete structures can simultaneously address the problems of steel corrosion and FRP bar micro-damage in concrete structures, while also meeting low-carbon requirements. However, due to the heterogeneous cross-section of this mixed reinforced concrete structure capable of actively storing CO2, existing cross-sectional design methods for concrete structures are unable to design such a concrete structure, thus restricting the production and manufacturing of active CO2-storing concrete beams. Summary of the Invention

[0005] In view of the defects and shortcomings of the existing technology, the purpose of the present invention is to provide a cross-sectional design method for concrete beams that actively seal up CO2, so as to solve the technical problem that the production and manufacturing of concrete beams that actively seal up CO2 are restricted due to the lack of cross-sectional design method for mixed reinforced concrete beams that actively seal up CO2 in the existing technology.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A cross-sectional design method for a concrete beam for active CO2 storage is proposed. The method first calculates and obtains the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the cross-sectional area. c ; Then according to the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section c , determine whether to design a single-reinforced rectangular section or a double-reinforced rectangular section; based on the judgment result, carry out a single-reinforced rectangular section design or a double-reinforced rectangular section design, and verify the designed single-reinforced rectangular section or double-reinforced rectangular section.

[0008] The present invention also has the following technical features:

[0009] The method specifically comprises the following steps:

[0010] The concrete beam specimen is divided into an unsealed CO2 concrete area and an actively sealed CO2 concrete area from the inside out; a reserved position for tensile steel bars is provided in the unsealed CO2 concrete area, and a reserved position for tensile FRP bars is provided in the actively sealed CO2 concrete area;

[0011] Or the unsealed CO2 concrete area is provided with reserved positions for tension reinforcement and compression reinforcement, and the active CO2 sealed concrete area is provided with reserved positions for tension FRP bars;

[0012] Step 2: Calculate and obtain the effective height h0 of the cross section of the concrete beam specimen described in step 1;

[0013] Step 3: Substitute the effective height h0 of the concrete beam specimen obtained in step 2 into formula I to calculate and obtain the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section. c ;

[0014] The vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section c Calculate and obtain according to formula I:

[0015] Mu=-0.32bf ct x c 2 +0.79bh0f ct x c +(f c -f ct )(b-2h t )(-0.24x c 2 +0.4h0x c ) +(fc -f ct )(b-2h t )(-0.07x c 2 +0.39h0x c +0.5h t 2 -h0h t ) Formula I;

[0016] In Formula 1:

[0017] M u It represents the design value of the section bending moment of the concrete beam specimen;

[0018] b represents the cross-sectional design width of the concrete beam specimen;

[0019] h represents the cross-sectional design height of the concrete beam specimen;

[0020] f ct Indicates the axial compressive strength of the concrete area for active CO2 storage;

[0021] f c Indicates the axial compressive strength of the concrete area without CO2 storage;

[0022] h t is the carbonization depth of the concrete beam specimen;

[0023] h0 represents the effective height of the cross section of the concrete beam specimen;

[0024] The h t 、f c 、f ct ,h,b,M u Substitute the values of h0 and h1 into formula I to calculate and obtain the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section. c ;

[0025] Step 4: According to the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone obtained in step 3, c Value, determine whether to design a single-reinforced rectangular section or a double-reinforced rectangular section: when x c β1 / h0≤ξ b When x c β1 / h0≤ξ b When the double-reinforced rectangular section is designed;

[0026] in:

[0027] x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section;

[0028] β1 represents the equivalent rectangular stress diagram coefficient;

[0029] h0 represents the effective height of the cross section of the concrete beam specimen;

[0030] ξ b Indicates the height of the limit relative to the compression zone;

[0031] Step 5: Based on the judgment result of step 4, design a single-reinforced rectangular section;

[0032] Step 6: Verify the single-reinforced rectangular section designed in step 5;

[0033] Step 7: Design a double-reinforced rectangular section based on the judgment result of step 4;

[0034] Step 8: Verify the double-reinforced rectangular section designed in step 7.

[0035] The step five specifically includes the following steps:

[0036] Step 5.1: Calculate and obtain the theoretical configuration area A of the tensile reinforcement in the concrete beam specimen according to formula II: S :

[0037] 0.8x c bf ct +(f c -f ct )(b-2h t )×0.4x c +(f c -f ct )(b-2h t )(0.39x c -h t ) =f fd A s1 +f y A s2 Formula II;

[0038] In Formula II:

[0039] x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section;

[0040] b represents the cross-sectional design width of the concrete beam specimen;

[0041] f ct Indicates the axial compressive strength of the concrete area for active CO2 storage;

[0042] f c Indicates the axial compressive strength of the concrete area without CO2 storage;

[0043] h t is the carbonization depth of the concrete beam specimen;

[0044] A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen;

[0045] A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen;

[0046] f fd Indicates the design value of tensile strength of FRP bars;

[0047] f y Indicates the design value of tensile strength of steel bars;

[0048] The x c , b, f ct 、f c and h t Substitute the numerical value of into formula II to obtain the theoretical configuration area A of the tensile composite reinforcement in the concrete beam specimen. S Expression III:

[0049]

[0050] In formula III:

[0051] A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen;

[0052] A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen;

[0053] f fd Indicates the design value of tensile strength of FRP bars;

[0054] f y Indicates the design value of tensile strength of steel bars;

[0055] The A S1 、A S2 、f fd and f y Substituting the numerical value of into formula III, the theoretical configuration area A of the tensile mixed reinforcement in the concrete beam specimen is calculated and obtained. S ;

[0056] Step 5.2: The theoretical configuration area A of the tensile reinforcement in the concrete beam specimen obtained in step 5.1 S , configure the diameter and quantity of tensile steel bars and tensile FRP bars, and complete the design of single-bar rectangular section.

[0057] The step six specifically includes the following steps:

[0058] Step 6.1: Calculate the mixed reinforcement ratio ρ according to Formula IV sf,s :

[0059]

[0060] In Formula IV:

[0061] ρ sf,s represents the mixed reinforcement ratio;

[0062] ρ s Indicates the reinforcement ratio of tensile steel bars;

[0063] ρ f represents the reinforcement ratio of tensile FRP bars;

[0064] f y Indicates the design value of tensile strength of steel bars;

[0065] f fd Indicates the design value of tensile strength of FRP bars;

[0066] A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen;

[0067] A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen;

[0068] b represents the cross-sectional design width of the concrete beam specimen;

[0069] h0 is the effective height of the concrete beam specimen;

[0070] The f y 、f fd 、A S1 、A S2 Substitute the values of b and h0 into formula IV to calculate and obtain the mixed reinforcement ratio ρ sf,s ;

[0071] Step 6.2: Based on the mixed reinforcement ratio ρ obtained in step 6.1 sf,s , and the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone obtained in step 3 c , determine whether the designed single-reinforced rectangular section meets the appropriate reinforcement failure mode;

[0072] When the mixed reinforcement ratio ρ sf,s Satisfies formula V, and the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section cWhen formula VI is satisfied, the designed single-reinforced rectangular section complies with the appropriate reinforcement failure mode;

[0073]

[0074] In Formula V:

[0075] ρ sf,s represents the mixed reinforcement ratio;

[0076] ρ s Indicates the reinforcement ratio of tensile steel bars;

[0077] ρ f represents the reinforcement ratio of tensile FRP bars;

[0078] f y Indicates the design value of tensile strength of steel bars;

[0079] f fd Indicates the design value of tensile strength of FRP bars;

[0080] f t It represents the design value of the axial tensile strength of the concrete beam specimen;

[0081] b represents the cross-sectional design width of the concrete beam specimen;

[0082] The ρ sf,s 、f t and f y Substitute the value of into formula V to determine the mixed reinforcement ratio ρ sf,s Whether formula V is satisfied;

[0083] β1x c ≤ξ b h0 Formula VI;

[0084] In Formula VI:

[0085] x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section;

[0086] β1 represents the equivalent rectangular stress diagram coefficient;

[0087] ξ b Indicates the height of the limit relative to the compression zone;

[0088] h0 represents the effective height of the cross section of the concrete beam specimen;

[0089] The x c ,β1,ξ b Substitute the values of h and h0 into formula VI to determine the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section. cWhether it satisfies Formula VI.

[0090] The step seven specifically includes the following steps:

[0091] Step 7.1 is basically the same as step 5.1 above, except that c Revalue and recalculate x c When taking the value, directly set ξ=ξ b , then x c =ξ b h0;

[0092] Step 7.2, obtain the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen;

[0093] After re-calculating the value of x in step 7.1 c , and the above h t 、f c 、f ct Substitute the values of h, b and h0 into formula I to calculate and obtain the maximum positive section bending bearing capacity M that can be provided by fully utilizing the concrete compression zone. U2 Then, the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen is calculated and obtained by formula VII;

[0094]

[0095] In Formula VII:

[0096] As' represents the theoretical configuration area of the compressive reinforcement in the concrete beam specimen;

[0097] M u represents the design value of the bending moment of the concrete beam specimen section;

[0098] M U2 It means making full use of the maximum positive section bending bearing capacity that can be provided by the concrete compression zone;

[0099] fy' represents the design value of the compressive strength of the steel bars in the concrete beam specimen;

[0100] h0 represents the effective height of the cross section of the concrete beam specimen;

[0101] as' represents the vertical distance from the resultant point of all the compressive reinforcements in the upper section of the concrete beam specimen to the edge of the compression zone of the section;

[0102] The M u 、M U2 Substitute the values of fy', h0 and as' into formula VII to calculate and obtain the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen;

[0103] Step 7.3: The theoretical configuration area A of the tensile reinforcement in the concrete beam specimen obtained in step 7.1 S , configure the diameter and number of tensile steel bars and tensile FRP bars; according to the theoretical configuration area As' of the compressive steel bars in the concrete beam specimen obtained in step 7.2, configure the diameter and number of the compressive steel bars to complete the design of the double-reinforced rectangular section.

[0104] The specific process of step eight is as follows:

[0105] According to the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section obtained in step 3, c , determine whether the designed double-reinforced rectangular section meets the appropriate reinforcement failure mode;

[0106] When the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section is c When both Equation VIII and Equation IX are satisfied, the double-reinforced rectangular section conforms to the appropriate reinforcement failure mode;

[0107] β1x c ≤ξ b h0 Formula VIII;

[0108] In Formula VIII:

[0109] β1 represents the equivalent rectangular stress diagram coefficient;

[0110] x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section;

[0111] ξ b Indicates the height of the limit relative to the compression zone;

[0112] h0 represents the effective height of the cross section of the concrete beam specimen;

[0113] β1x c ≥2as' Formula IX;

[0114] In Formula IX:

[0115] x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section;

[0116] β1 represents the equivalent rectangular stress diagram coefficient;

[0117] as' represents the vertical distance from the resultant point of all the compressive reinforcements in the upper section of the concrete beam specimen to the edge of the compression zone of the section;

[0118] The x c ,β1,ξ bSubstitute the values of x and h0 into Equation VIII, and c ,ξ b Substitute the values of and as' into formula IX to determine the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section. c Whether Formula VIII and Formula IX are satisfied at the same time.

[0119] Specifically, in step 2, the effective cross-sectional height h0 of the concrete beam specimen is calculated and obtained according to formula X:

[0120] h0=h﹣a S Formula X;

[0121] In formula X:

[0122] h0 represents the effective height of the cross section of the concrete beam specimen;

[0123] h represents the cross-sectional design height of the concrete beam specimen;

[0124] a S It represents the vertical distance from the resultant force point of all tensile reinforcements in the lower part of the concrete beam specimen to the edge of the tensile zone of the section;

[0125] The h and a S Substitute the numerical value into formula X to calculate and obtain the effective cross-sectional height h0 of the concrete beam specimen.

[0126] Specifically, in step 1, the cross-sectional design area Ar of the concrete beam specimen is expressed according to formula XI:

[0127] Ar=b×h Formula XI;

[0128] In Formula XI:

[0129] Ar represents the cross-sectional design area of the concrete beam specimen;

[0130] b represents the cross-sectional design width of the concrete beam specimen;

[0131] h represents the cross-sectional design height of the concrete beam specimen.

[0132] Compared with the prior art, the present invention has the following beneficial technical effects:

[0133] (I) This invention proposes for the first time a cross-sectional design method for concrete beams for active CO2 storage. This method first calculates and obtains the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the cross-sectional area. c ; Then according to the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section c, determining whether to design a single-reinforced or double-reinforced rectangular cross-section; based on the determination, performing the single-reinforced or double-reinforced rectangular cross-section design, and verifying the designed single-reinforced or double-reinforced rectangular cross-section. This method fills a gap in the cross-sectional design of hybrid reinforced concrete beams for active CO2 storage, thereby promoting the production and manufacturing of such concrete beams.

[0134] (II) The cross-sectional design method of the concrete beam for active CO2 sequestration of the present invention provides a theoretical basis for solving the problems of easy corrosion of steel bars and microscopic damage of FRP bars in concrete structures, while also taking into account the low-carbon requirements of concrete beams. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] Figure 1 Schematic diagram of the parameters for the cross-sectional design method of concrete beams for active CO2 storage.

[0136] Figure 2 Schematic diagram of the single-reinforced rectangular cross-section designed in Example 1.

[0137] Figure 3 Schematic diagram of the double-reinforced rectangular section designed in Example 2.

[0138] The meanings of the numbers in the figure are: 1-concrete area without CO2 sealing, 2-concrete area with active CO2 sealing, 3-reserved position for tensile reinforcement, 4-reserved position for tensile FRP bars, 5-reserved position for compressive reinforcement, 6-tensile reinforcement, 7-tensile FRP bars, 8-compressive reinforcement, 9-staffing bars, 10-preset FRP bars, 11-edge of the tensile zone of the section, 12-edge of the compressive zone of the section;

[0139] b represents the cross-sectional design width of the concrete beam specimen; h represents the cross-sectional design height of the concrete beam specimen; h0 represents the effective cross-sectional height of the concrete beam specimen; h t Indicates the carbonization depth of the concrete beam specimen; a s It represents the vertical distance from the resultant point of all tensile reinforcements in the lower section of the concrete beam specimen to the edge of the tensile zone of the section; as' represents the vertical distance from the resultant point of all compressive reinforcements in the upper section of the concrete beam specimen to the edge of the compressive zone of the section.

[0140] The technical solution of the present invention is further described below in conjunction with embodiments. DETAILED DESCRIPTION

[0141] In the present invention:

[0142] The tensile FRP bars and the pre-set FRP bars are both glass fiber reinforced bars (GFRP bars) known in the prior art. The reinforcement bars are conventional reinforcement bars known in the prior art.

[0143] The specific meaning of the appropriate reinforcement failure mode is: when the reinforcement ratio of the concrete beam is within an appropriate range, when the load is large, the longitudinal reinforcement of the concrete beam will yield first, and then the concrete beam will be crushed.

[0144] The neutral axis refers to the axis where the normal stress in the positive section direction of the concrete beam specimen is equal to zero.

[0145] The concrete used to prepare the concrete beam specimens was prepared using cement, fly ash, coarse aggregate and river sand as raw materials, and the mass mix ratio of the cement, fly ash, coarse aggregate and river sand was 1.63:0.18:4.85:3.26.

[0146] Specifically, the cement clinker contains the following oxides: 56.57% by mass of CaO, 18.87% by mass of SiO2, 5.43% by mass of Al2O3, 3.45% by mass of Fe2O3, 2.55% by mass of MgO, 3.73% by mass of SO3, 1.19% by mass of K2O, and 0.36% by mass of Na2O.

[0147] Specifically, the fly ash contains the following oxides: 9.25% by mass of CaO, 38.87% by mass of SiO2, 11.40% by mass of Al2O3, 13.21% by mass of Fe2O3, 6.08% by mass of MgO, 0.17% by mass of SO3, 0.97% by mass of K2O, and 2.55% by mass of Na2O.

[0148] Specifically, the coarse aggregate is continuously graded crushed stone with a particle size of 5mm to 20mm.

[0149] Specifically, the river sand is medium sand with an average particle size of 0.35mm to 0.5mm.

[0150] The concrete beam specimen preparation process is as follows: after setting up the formwork and tying the tensile steel bars 6, tensile FRP bars 7, frame bars 9, and pre-set FRP bars 10, or after tying the tensile steel bars 6, tensile FRP bars 7, compressive steel bars 8, frame bars 9, and pre-set FRP bars 10, pouring the concrete, and then curing it at room temperature (20-25°C) and 60% relative humidity for 4-8 hours to produce the precast concrete beam specimen. The precast concrete beam specimen is then transferred to a carbonation test chamber at a carbon dioxide concentration of 95%, a humidity of 60%, a temperature of 25°C, and a standard atmospheric pressure. After carbonation curing for 28 days, the concrete beam specimen is produced.

[0151] It should be noted that the values of all design parameters in the present invention are conventional values determined by those skilled in the art based on actual working conditions unless otherwise specified. For example, the design value M of the section bending moment of a concrete beam specimen is u , axial compressive strength of the active CO2 storage concrete area f ct , the axial compressive strength of the unsealed CO2 concrete area, and the carbonization depth h of the concrete beam specimens t , equivalent rectangular stress diagram coefficient β1, boundary relative compression zone height ξ b , the cross-sectional design width b of the concrete beam specimen, the cross-sectional design height h of the concrete beam specimen, the tensile strength design value f of the FRP reinforcement fd , design value of tensile strength of steel bar f y , the design value of the axial tensile strength of the concrete beam specimen f t wait.

[0152] In accordance with the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0153] Example 1:

[0154] This embodiment provides a cross-section design method for a concrete beam, such as Figure 2 As shown, the method specifically includes the following steps:

[0155] Step 1: Design concrete beam specimens;

[0156] The concrete used to prepare the concrete beam specimens was made from cement, fly ash, coarse aggregate and river sand. The mass mix ratio of cement, fly ash, coarse aggregate and river sand was 1.63:0.18:4.85:3.26.

[0157] The concrete beam specimen is divided into an unsealed CO2 concrete area 1 and an actively sealed CO2 concrete area 2 from the inside out. A reserved position 3 for tensile steel bars is provided in the unsealed CO2 concrete area 1, and a reserved position 4 for tensile FRP bars is provided in the actively sealed CO2 concrete area 2.

[0158] Or the unsealed CO2 concrete area 1 is provided with a reserved position 3 for tensile reinforcement and a reserved position 5 for compressive reinforcement, and the actively sealed CO2 concrete area 2 is provided with a reserved position 4 for tensile FRP bars;

[0159] In this embodiment, the tensile reinforcement 6, compressive reinforcement 8, and tensile FRP bars 7 in the concrete beam specimens are classified according to common knowledge in the art. For example, if all the reinforcement is installed in the concrete beam, the reinforcement below the mid-span and above the support are generally considered tensile reinforcement, while the reinforcement above the mid-span and below the support are considered compressive reinforcement.

[0160] In this embodiment, the active CO2 sealing concrete area 2 is further provided with frame bars 8. The frame bars 8 are generally steel bars, and the setting method of the frame bars 8 can adopt the conventional setting method of those skilled in the art; the active CO2 sealing concrete area 2 is also provided with preset FRP bars 9. The preset FRP bars 9 are arranged around the outside of the reserved position 4 for the tensile FRP bars.

[0161] According to the thickness of the reserved steel bar space and the mass mix ratio of concrete, combined with experiments, the sealing temperature and sealing time used when the concrete beam specimen actively seals CO2 are determined; in this embodiment, the sealing temperature used is 25°C and the sealing time used is 28 days.

[0162] The cross-sectional design area Ar of the concrete beam specimen is expressed according to formula XI:

[0163] Ar=b×h Formula XI;

[0164] In Formula XI:

[0165] Ar represents the cross-sectional design area of the concrete beam specimen;

[0166] b represents the cross-sectional design width of the concrete beam specimen. In this embodiment, b is 300 mm;

[0167] h represents the cross-sectional design height of the concrete beam specimen. In this embodiment, h is 600 mm;

[0168] Step 2: Calculate and obtain the effective cross-sectional height h0 of the concrete beam specimen described in step 1; the effective cross-sectional height h0 of the concrete beam specimen is calculated and obtained according to formula X:

[0169] h0=h﹣a S Formula X;

[0170] In formula X:

[0171] h0 represents the effective height of the cross section of the concrete beam specimen;

[0172] h represents the cross-sectional design height of the concrete beam specimen. In this embodiment, h is 600 mm;

[0173] a SIt represents the vertical distance from the resultant point of all tensile reinforcements in the lower section of the concrete beam specimen to the edge of the tensile zone of the section, a S The value of is determined by the thickness of the FRP bar protective layer. The thickness of the FRP bar protective layer is designed according to the preset FRP bar 10 and the tension FRP bar 6, and needs to be slightly larger than the diameter of the preset FRP bar 9 and the diameter of the tension FRP bar 6. In this embodiment, the thickness of the FRP bar protective layer is 20mm, so a S Take 40mm.

[0174] The above h and a S Substituting the numerical value into formula IX, the effective cross-sectional height h0 of the concrete beam specimen is calculated and obtained as 560 mm.

[0175] Step 3: Substitute the effective height h0 of the concrete beam specimen obtained in step 2 into formula I to calculate and obtain the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the tensile zone of the section. c ;

[0176] Mu=-0.32bf ct x c 2 +0.79bh0f ct x c +(f c -f ct )(b-2h t )(-0.24x c 2 +0.4h0x c ) +(f c -f ct )(b-2h t )(-0.07x c 2 +0.39h0x c +0.5h t 2 -h0h t ) Formula I;

[0177] In Formula 1:

[0178] M u represents the design value of the cross-sectional bending moment of the concrete beam specimen. In this embodiment, M u 300 kN·m;

[0179] b represents the cross-sectional design width of the concrete beam specimen. In this embodiment, b is 300 mm;

[0180] h represents the cross-sectional design height of the concrete beam specimen. In this embodiment, h is 600 mm;

[0181] fct represents the axial compressive strength of the active CO2 storage concrete area. In this embodiment, f ct 16.7N / mm 2 ;

[0182] f c represents the axial compressive strength of the unsealed CO2 concrete area. In this embodiment, f c 14.3N / mm 2 ;

[0183] h t To express the carbonization depth of the concrete beam specimen, in this embodiment, h t 40mm;

[0184] h0 represents the effective height of the cross section of the concrete beam specimen. In this embodiment, h0 is 560 mm;

[0185] The above h t 、f c 、f ct ,h,b,M u Substitute the values of h0 and h1 into formula I to calculate and obtain the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section. c It is 167mm.

[0186] Step 4: According to the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone obtained in step 3, c Value, determine whether to design a single-reinforced rectangular section or a double-reinforced rectangular section: when x c β1 / h0≤ξ b When x c β1 / h0≤ξ b When the double-reinforced rectangular section is designed;

[0187] in:

[0188] x c represents the vertical distance from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section. In this embodiment, x c 167mm;

[0189] β1 represents the equivalent rectangular stress diagram coefficient. In this embodiment, β1 is 0.8;

[0190] h0 represents the effective height of the cross section of the concrete beam specimen. In this embodiment, h0 is 560 mm;

[0191] ξ b Indicates the height of the boundary relative to the pressure zone. In this embodiment, ξ b is 0.518;

[0192] In this embodiment, x c β1 / h0=167×0.8 / 560mm=0.238,0.238<0.518,that is, x c β1 / h0≤ξ b , so a single-reinforced rectangular section design is performed.

[0193] Step 5: Based on the judgment result of step 4, design a single-reinforced rectangular section;

[0194] Step 5.1: Calculate and obtain the theoretical configuration area A of the tensile reinforcement in the concrete beam specimen according to formula II: S :

[0195] 0.8x c bf ct +(f c -f ct )(b-2h t )×0.4x c +(f c -f ct )(b-2h t )(0.39x c -h t ) =f fd A s1 +f y A s2 Formula II;

[0196] In Formula II:

[0197] x c represents the vertical distance from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section. In this embodiment, x c 167mm;

[0198] b represents the cross-sectional design width of the concrete beam specimen. In this embodiment, b is 300 mm;

[0199] f ct represents the axial compressive strength of the active CO2 storage concrete area. In this embodiment, f ct 16.7N / mm 2 ;

[0200] f c represents the axial compressive strength of the unsealed CO2 concrete area. In this embodiment, f c 14.3N / mm 2 ;

[0201] h t To express the carbonization depth of the concrete beam specimen, in this embodiment, h t 40mm;

[0202] A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen;

[0203] A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen;

[0204] f fd represents the design value of the tensile strength of the FRP bar. In this embodiment, f fd 704N / mm 2 ;

[0205] f y represents the design value of the tensile strength of the steel bar. In this embodiment, f y 360N / mm 2 ;

[0206] In this embodiment, Formula II is derived according to the force balance of the concrete beam specimen in the horizontal direction.

[0207] The above x c , b, f ct 、f c and h t Substitute the numerical value of into formula II to obtain the theoretical configuration area A of the tensile composite reinforcement in the concrete beam specimen. S Expression III:

[0208]

[0209] In formula III:

[0210] A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen;

[0211] A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen;

[0212] f fd represents the design value of the tensile strength of the FRP bar. In this embodiment, f fd 704N / mm 2 ;

[0213] f y represents the design value of the tensile strength of the steel bar. In this embodiment, f y 360N / mm 2 ;

[0214] In this embodiment, the theoretical configuration area A of the tensile mixed reinforcement in the concrete beam specimen is finally calculated and obtained. S 1717mm 2 .

[0215] Step 5.2: The theoretical configuration area A of the tensile reinforcement in the concrete beam specimen obtained in step 5.1 S , combined with actual engineering requirements, the diameter and number of tension reinforcement materials are configured to complete the single-reinforcement rectangular section design; in this embodiment, it is finally selected to configure four tension FRP bars 7 with a diameter of 16 mm at the tension FRP bar reserved position 4, and to configure four tension steel bars 6 with a diameter of 16 mm at the tension steel bar reserved position 3.

[0216] Step 6: Verify the single-reinforced rectangular section designed in step 5;

[0217] Step 6.1: Calculate the mixed reinforcement ratio ρ according to Formula IV sf,s :

[0218]

[0219] In Formula IV:

[0220] ρ sf,s represents the mixed reinforcement ratio;

[0221] ρ s represents the tensile reinforcement ratio. In this embodiment, ρ s 0.48%;

[0222] ρ f represents the tensile FRP reinforcement ratio. In this embodiment, ρ f 0.48%;

[0223] f y represents the design value of the tensile strength of the steel bar. In this embodiment, f y 360N / mm 2 ;

[0224] f fd represents the design value of the tensile strength of the FRP bar. In this embodiment, f fd 704N / mm 2 ;

[0225] A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen. In this embodiment, A S1 804mm 2 ;

[0226] A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen. In this embodiment, A S2 804mm 2 ;

[0227] b represents the cross-sectional design width of the concrete beam specimen. In this embodiment, b is 300 mm;

[0228] h0 is the effective height of the concrete beam specimen. In this embodiment, h0 is 560 mm.

[0229] f y 、f fd 、A S1 、A S2 Substitute the values of b and h0 into formula IV to calculate and obtain the mixed reinforcement ratio ρ sf,s It is 1.4%.

[0230] Step 6.2: Based on the mixed reinforcement ratio ρ obtained in step 6.1 sf,s , and the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone obtained in step 3 c , determine whether the designed single-reinforced rectangular section meets the appropriate reinforcement failure mode;

[0231] When the mixed reinforcement ratio ρ sf,s Satisfies formula V, and the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section c When formula VI is satisfied, the designed single-reinforced rectangular section complies with the appropriate reinforcement failure mode;

[0232]

[0233] In Formula V:

[0234] ρ sf,s Represents the mixed reinforcement ratio. In this embodiment, ρ sf,s 1.4%;

[0235] ρ s represents the tensile reinforcement ratio. In this embodiment, ρ s 0.48%;

[0236] ρ f represents the tensile FRP reinforcement ratio. In this embodiment, ρ f 0.48%;

[0237] f y represents the design value of the tensile strength of the steel bar. In this embodiment, f y 360N / mm 2 ;

[0238] f fd represents the design value of the tensile strength of the FRP bar. In this embodiment, f fd 704N / mm 2 ;

[0239] ft represents the design value of the axial tensile strength of the concrete beam specimen. In this embodiment, f t 1.43N / mm 2 ;

[0240] b represents the cross-sectional design width of the concrete beam specimen. In this embodiment, b is 300 mm;

[0241] The above ρ sf,s 、f t and f y Substituting the value of into formula V, we get 1.4%>0.2%, which is the mixed reinforcement ratio ρ in this embodiment. sf,s Satisfy formula V.

[0242] β1x c ≤ξ b h0 Formula VI;

[0243] In Formula VI:

[0244] x c represents the vertical distance from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section. In this embodiment, x c 167mm;

[0245] β1 represents the equivalent rectangular stress diagram coefficient. In this embodiment, β1 is 0.8;

[0246] ξ b Indicates the height of the boundary relative to the pressure zone. In this embodiment, ξ b is 0.518;

[0247] h0 represents the effective height of the cross section of the concrete beam specimen. In this embodiment, h0 is 560 mm;

[0248] The above x c ,β1,ξ b Substituting the values of h0 and h1 into formula VI, we obtain 133.6 mm < 290.8 mm, which is the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the tensile zone of the section in this embodiment. c Satisfies formula VI.

[0249] In this embodiment, the final designed mixed reinforcement ratio ρ sf,s Satisfies formula V, and the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section c Formula VI is satisfied, that is, the single-reinforced rectangular cross-section finally designed in this embodiment conforms to the appropriate reinforcement failure mode and can meet actual engineering requirements.

[0250] Example 2:

[0251] This embodiment provides a cross-section design method for a concrete beam, such as Figure 3 As shown, the method specifically includes the following steps:

[0252] In this embodiment, step 1 is the same as step 1 in embodiment 1.

[0253] In this embodiment, step 2 is the same as step 2 in embodiment 1.

[0254] In this embodiment, step three is basically the same as step three of embodiment 1, except that in this embodiment, the design value M of the cross-sectional bending moment of the concrete beam specimen is u The calculated vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone is 550 kN·m. c It is 375mm.

[0255] Step 4: Step 4 is basically the same as Step 4 in Example 1, except that in this embodiment, x c β1 / h0=375mm×0.8 / 560mm=0.6, 0.6>0.518, that is, x c β1 / h0>ξ b , so a double-reinforced rectangular cross-section design is performed;

[0256] Step 7: Design a double-reinforced rectangular section based on the judgment result of step 4;

[0257] In this embodiment, step 7.1 is substantially the same as step 5.1 in embodiment 1, except that c Revalue and recalculate x c When taking the value, directly set ξ=ξ b , then x c =ξ b h0; In this embodiment, the revalued x c The theoretical configuration area A of the tensile reinforcement in the concrete beam specimen is finally calculated and obtained. S 4144mm 2 .

[0258] Step 7.2, obtain the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen;

[0259] After re-calculating the value of x in step 7.1 c , and the above h t 、f c 、f ct Substitute the values of h, b and h0 into formula I to calculate and obtain the maximum positive section bending bearing capacity M that can be provided by fully utilizing the concrete compression zone. U2Then, the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen is calculated and obtained by formula VII;

[0260]

[0261] In Formula VII:

[0262] As' represents the theoretical configuration area of the compressive reinforcement in the concrete beam specimen;

[0263] M u represents the design value of the bending moment of the concrete beam specimen section. In this embodiment, M u 550 kN·m;

[0264] M U2 Indicates that the maximum positive section bending bearing capacity that can be provided by the concrete compression zone is fully utilized. In this embodiment, M U2 500 kN·m;

[0265] fy' represents the design compressive strength of the steel bars in the concrete beam specimen. In this embodiment, fy' is 360 kN·m;

[0266] h0 represents the effective height of the cross section of the concrete beam specimen. In this embodiment, h0 is 560 mm;

[0267] as' represents the vertical distance from the resultant point of all the compressive reinforcements in the upper section of the concrete beam specimen to the edge of the compression zone of the section. In this embodiment, as' is 40 mm;

[0268] The above M u 、M U2 Substituting the values of fy', h0 and as' into Equation VII, the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen is calculated to be 267mm 2 , this value meets the minimum standard required by the project.

[0269] Step 7.3: The theoretical configuration area A of the tensile reinforcement in the concrete beam specimen obtained in step 7.1 S , combined with the actual project requirements, configure the diameter and number of tensile reinforcement; based on the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen obtained in step 7.2, combined with the actual project requirements, configure the diameter and number of compressive reinforcement to complete the double-reinforced rectangular section design.

[0270] In this embodiment, four 20mm diameter tensile FRP bars 7 and six 22mm diameter tensile steel bars 6 were finally selected. Two 14mm diameter compressive steel bars 8 were configured in the compression zone. The actual configuration area of the compressive steel bars in the concrete beam specimen is 308mm.2 , which is greater than the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen.

[0271] Step 8: Verify the double-reinforced rectangular section designed in step 7;

[0272] According to the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section obtained in step 3, c , determine whether the designed double-reinforced rectangular section meets the appropriate reinforcement failure mode;

[0273] When the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section is c When both Equation VIII and Equation IX are satisfied, the double-reinforced rectangular section conforms to the appropriate reinforcement failure mode;

[0274] β1x c ≤ξ b h0 Formula VIII;

[0275] In Formula VIII:

[0276] β1 represents the equivalent rectangular stress diagram coefficient. In this embodiment, β1 is 0.8;

[0277] x c It represents the vertical distance from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section. In this embodiment, the revalued x c 290mm;

[0278] ξ b Indicates the height of the boundary relative to the pressure zone. In this embodiment, ξ b is 0.518;

[0279] h0 represents the vertical distance from the resultant force point to the edge of the compression zone of the concrete beam specimen. In this embodiment, h0 is 560 mm.

[0280] β1x c ≥2as' Formula IX;

[0281] In Formula IX:

[0282] x c It represents the vertical distance from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section. In this embodiment, the revalued x c 290mm;

[0283] ξ b Indicates the height of the boundary relative to the pressure zone. In this embodiment, ξ b is 0.518;

[0284] as' represents the vertical distance from the resultant point of all the compressive reinforcements in the upper section of the concrete beam specimen to the edge of the compression zone of the section. In this embodiment, as' is 40 mm;

[0285] The above revalued x c ,β1,ξ b Substitute the values of and h0 into Equation VIII, and replace the above revalued x c ,ξ b Substitute the values of and as' into Formula IX. In this embodiment, the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section is c At the same time, Formula VIII and Formula IX are satisfied, that is, the double-reinforced rectangular cross-section finally designed in this embodiment conforms to the appropriate reinforcement failure mode and can meet actual engineering requirements.

Claims

1. A cross-sectional design method for a concrete beam for active CO2 storage, characterized in that: This method first calculates and obtains the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section based on the design value of the bending moment. c Then according to the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section c , determine whether to design a single-reinforced rectangular section or a double-reinforced rectangular section; based on the determination result, perform a single-reinforced rectangular section design or a double-reinforced rectangular section design, and verify the designed single-reinforced rectangular section or double-reinforced rectangular section; specifically, the steps include: Step 1: Design concrete beam specimens; The concrete beam specimen is composed of an unsealed CO2 concrete area (1) and an actively sealed CO2 concrete area (2) from the inside out; a reserved position for tensioned steel bars (3) is provided in the unsealed CO2 concrete area (1), and a reserved position for tensioned FRP bars (4) is provided in the actively sealed CO2 concrete area (2); Or the unsealed CO2 concrete area (1) is provided with a reserved position for tension steel bars (3) and a reserved position for compression steel bars (5), and the actively sealed CO2 concrete area (2) is provided with a reserved position for tension FRP bars (4); Step 2: Calculate and obtain the effective height h0 of the cross section of the concrete beam specimen described in step 1; Step 3: Substitute the effective height h0 of the concrete beam specimen obtained in step 2 into formula I to calculate and obtain the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section. c ; The vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section c Calculate and obtain according to formula I: Mu = -0.32bf ct x c 2 +0.79bh0f ct x c +(f c -f ct )(b - 2h t )(-0.24x c 2 +0.4h0x c )+(f c -f ct )(b - 2h t )(-0.07x c 2 +0.39h0x c +0.5h t 2 -h0h t ) Equation I; In Formula 1: M u It represents the design value of the section bending moment of the concrete beam specimen; b represents the cross-sectional design width of the concrete beam specimen; h represents the cross-sectional design height of the concrete beam specimen; f ct Indicates the axial compressive strength of the concrete area for active CO2 storage; f c Indicates the axial compressive strength of the concrete area without CO2 storage; h t To represent the carbonization depth of the concrete beam specimen; h0 represents the effective height of the cross section of the concrete beam specimen; The h t 、f c 、f ct ,h,b,M u Substitute the values of h0 and h1 into formula I to calculate and obtain the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section. c ; Step 4: According to the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone obtained in step 3, c Value, determine whether to design a single-reinforced rectangular section or a double-reinforced rectangular section: when x c β1 / h0≤ξ b When x c β1 / h0≤ξ b When the double-reinforced rectangular section is designed; in: x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section; β1 represents the equivalent rectangular stress diagram coefficient; h0 represents the effective height of the cross section of the concrete beam specimen; ξ b Indicates the height of the limit relative to the compression zone; Step 5: Based on the judgment result of step 4, design a single-reinforced rectangular section; Step 6: Verify the single-reinforced rectangular section designed in step 5; Step 7: Design a double-reinforced rectangular section based on the judgment result of step 4; Step 8: Verify the double-reinforced rectangular section designed in step 7.

2. The cross-section design method for a concrete beam for active CO2 storage according to claim 1, characterized in that: The step five specifically includes the following steps: Step 5.1: Calculate and obtain the theoretical configuration area A of the tensile reinforcement in the concrete beam specimen according to formula II: S : <h2 style=";text-align:left;direction:ltr">0.8x<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> bf<h2 style=";text-align:left;direction:ltr"> ct <h2 style=";text-align:left;direction:ltr"> +(f<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> -f<h2 style=";text-align:left;direction:ltr"> ct <h2 style=";text-align:left;direction:ltr"> b-2h<h2 style=";text-align:left;direction:ltr"> t <h2 style=";text-align:left;direction:ltr"> )×0.4x<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> +(f<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> -f<h2 style=";text-align:left;direction:ltr"> ct <h2 style=";text-align:left;direction:ltr"> b-2h<h2 style=";text-align:left;direction:ltr"> t <h2 style=";text-align:left;direction:ltr"> )(0.39x<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> -h<h2 style=";text-align:left;direction:ltr"> t <h2 style=";text-align:left;direction:ltr"> ) = f fd A s1 + f y A s2 Formula II; In Formula II: x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section; b represents the cross-sectional design width of the concrete beam specimen; f ct Indicates the axial compressive strength of the concrete area for active CO2 storage; f c Indicates the axial compressive strength of the concrete area without CO2 storage; h t To represent the carbonization depth of the concrete beam specimen; A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen; A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen; f fd Indicates the design value of tensile strength of FRP bars; f y Indicates the design value of tensile strength of steel bars; The x c , b, f ct 、f c and h t Substitute the numerical value of into formula II to obtain the theoretical configuration area A of the tensile composite reinforcement in the concrete beam specimen. S Expression III: In formula III: A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen; A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen; f fd Indicates the design value of tensile strength of FRP bars; f y Indicates the design value of tensile strength of steel bars; The A S1 、A S2 、f fd and f y Substituting the numerical value of into formula III, the theoretical configuration area A of the tensile mixed reinforcement in the concrete beam specimen is calculated and obtained. S ; Step 5.2: The theoretical configuration area A of the tensile reinforcement in the concrete beam specimen obtained in step 5.1 S , configure the diameter and quantity of the tensile steel bars (6) and the tensile FRP bars (7) to complete the design of the single-bar rectangular section.

3. The cross-section design method for a concrete beam for active CO2 storage according to claim 1, characterized in that: The step six specifically includes the following steps: Step 6.1, calculate the mixed reinforcement ratio ρ according to formula IV sf,s : In Formula IV: ρ sf,s represents the mixed reinforcement ratio; ρ s Indicates the reinforcement ratio of tensile steel bars; ρ f represents the tensile FRP reinforcement ratio; f y Indicates the design value of tensile strength of steel bars; f fd Indicates the design value of tensile strength of FRP bars; A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen; A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen; b represents the cross-sectional design width of the concrete beam specimen; h0 is the effective height of the concrete beam specimen; The f y 、f fd 、A S1 、A S2 Substitute the values of b and h0 into formula IV to calculate and obtain the mixed reinforcement ratio ρ sf,s ; Step 6.2: Based on the mixed reinforcement ratio ρ obtained in step 6.1 sf,s , and the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone obtained in step 3 c , determine whether the designed single-reinforced rectangular section meets the appropriate reinforcement failure mode; When the mixed reinforcement ratio ρ sf,s Satisfies formula V, and the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section c When formula VI is satisfied, the designed single-reinforced rectangular section complies with the appropriate reinforcement failure mode; In Formula V: ρ sf,s represents the mixed reinforcement ratio; ρ s Indicates the reinforcement ratio of tensile steel bars; ρ f represents the tensile FRP reinforcement ratio; f y Indicates the design value of tensile strength of steel bars; f fd Indicates the design value of tensile strength of FRP bars; f t It represents the design value of the axial tensile strength of the concrete beam specimen; b represents the cross-sectional design width of the concrete beam specimen; The ρ sf,s 、f t and f y Substitute the value of into formula V to determine the mixed reinforcement ratio ρ sf,s Whether formula V is satisfied; β1x c ≤ξ b h0 Formula VI; In Formula VI: x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section; β1 represents the equivalent rectangular stress diagram coefficient; ξ b Indicates the height of the limit relative to the compression zone; h0 represents the effective height of the cross section of the concrete beam specimen; The x c ,β1,ξ b Substitute the values of h and h0 into formula VI to determine the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section. c Whether it satisfies Formula VI.

4. The cross-section design method for a concrete beam for active CO2 storage according to claim 1, characterized in that: The step seven specifically includes the following steps: Step 7.1, first c Revalue and recalculate x c When taking the value, directly set ξ=ξ b , then x c =ξ b h0; then according to formula II, calculate and obtain the theoretical configuration area A of the tensile mixed reinforcement in the concrete beam specimen S ; <h2 style=";text-align:left;direction:ltr">0.8x<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> bf<h2 style=";text-align:left;direction:ltr"> ct <h2 style=";text-align:left;direction:ltr"> +(f<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> -f<h2 style=";text-align:left;direction:ltr"> ct <h2 style=";text-align:left;direction:ltr"> b-2h<h2 style=";text-align:left;direction:ltr"> t <h2 style=";text-align:left;direction:ltr"> )×0.4x<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> +(f<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> -f<h2 style=";text-align:left;direction:ltr"> ct <h2 style=";text-align:left;direction:ltr"> b-2h<h2 style=";text-align:left;direction:ltr"> t <h2 style=";text-align:left;direction:ltr"> )(0.39x<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> -h<h2 style=";text-align:left;direction:ltr"> t <h2 style=";text-align:left;direction:ltr"> ) = f fd A s1 + f y A s2 Formula II; In Formula II: x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section; b represents the cross-sectional design width of the concrete beam specimen; f ct Indicates the axial compressive strength of the concrete area for active CO2 storage; f c Indicates the axial compressive strength of the concrete area without CO2 storage; h t To represent the carbonization depth of the concrete beam specimen; A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen; A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen; f fd Indicates the design value of tensile strength of FRP bars; f y Indicates the design value of tensile strength of steel bars; The revalued x c , b, f ct 、f c and h t Substitute the numerical value of into formula II to obtain the theoretical configuration area A of the tensile composite reinforcement in the concrete beam specimen. S Expression III: In formula III: A S1 represents the total cross-sectional area of the tensile FRP bars in the concrete beam specimen; A S2 represents the total cross-sectional area of the tensile reinforcement in the concrete beam specimen; f fd Indicates the design value of tensile strength of FRP bars; f y Indicates the design value of tensile strength of steel bars; The A S1 、A S2 、f fd and f y Substituting the numerical value of into formula III, the theoretical configuration area A of the tensile mixed reinforcement in the concrete beam specimen is calculated and obtained. S ; Step 7.2, obtain the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen; After re-calculating the value of x in step 7.1 c , and the h t 、f c 、f ct Substitute the values of h, b and h0 into the above formula I to calculate and obtain the maximum positive section bending bearing capacity M that can be provided by fully utilizing the concrete compression zone. U2 Then, the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen is calculated and obtained by formula VII: In Formula VII: As' represents the theoretical configuration area of the compressive reinforcement in the concrete beam specimen; M u represents the design value of the bending moment of the concrete beam specimen section; M U2 It means making full use of the maximum positive section bending bearing capacity that can be provided by the concrete compression zone; fy' represents the design value of the compressive strength of the steel bars in the concrete beam specimen; h0 represents the effective height of the cross section of the concrete beam specimen; as' represents the vertical distance from the resultant point of all the compressive reinforcements in the upper section of the concrete beam specimen to the edge of the compression zone of the section; The M u 、M U2 Substitute the values of fy', h0 and as' into formula VII to calculate and obtain the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen; Step 7.3: The theoretical configuration area A of the tensile reinforcement in the concrete beam specimen obtained in step 7.1 S , configure the diameter and quantity of the tensile reinforcement (6) and the tensile FRP reinforcement (7); according to the theoretical configuration area As' of the compressive reinforcement in the concrete beam specimen obtained in step 7.2, configure the diameter and quantity of the compressive reinforcement (8) to complete the design of the double-reinforced rectangular section.

5. The cross-section design method for a concrete beam for active CO2 storage according to claim 1, characterized in that: The specific process of step eight is as follows: According to the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section obtained in step 3, c , determine whether the designed double-reinforced rectangular section meets the appropriate reinforcement failure mode; When the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section is c When both Equation VIII and Equation IX are satisfied, the double-reinforced rectangular section conforms to the appropriate reinforcement failure mode; β1x c ≤ξ b h0 formula VIII; In Formula VIII: β1 represents the equivalent rectangular stress diagram coefficient; x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section; ξ b Indicates the height of the limit relative to the compression zone; h0 represents the effective height of the cross section of the concrete beam specimen; β1x c ≥2as' formula IX; In Formula IX: x c It represents the vertical distance from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section; β1 represents the equivalent rectangular stress diagram coefficient; as' represents the vertical distance from the resultant point of all the compressive reinforcements in the upper section of the concrete beam specimen to the edge of the compression zone of the section; The x c ,β1,ξ b Substitute the values of x and h0 into Equation VIII, and c ,ξ b Substitute the values of and as' into formula IX to determine the vertical distance x from the neutral axis of the concrete beam specimen section to the edge of the compression zone of the section. c Whether Formula VIII and Formula IX are satisfied at the same time.

6. The cross-section design method for a concrete beam for active CO2 storage according to claim 1, characterized in that: In step 2, the effective height h0 of the cross section of the concrete beam specimen is calculated and obtained according to formula X: h0=h﹣a S Formula X; In formula X: h0 represents the effective height of the cross section of the concrete beam specimen; h represents the cross-sectional design height of the concrete beam specimen; a S It represents the vertical distance from the resultant force point of all tensile reinforcements in the lower section of the concrete beam specimen to the edge of the tensile zone of the section; The h and a S Substitute the numerical value into formula X to calculate and obtain the effective cross-sectional height h0 of the concrete beam specimen.

7. The cross-section design method for a concrete beam for active CO2 storage according to claim 1, characterized in that: In step 1, the cross-sectional design area Ar of the concrete beam specimen is expressed according to formula XI: Ar=b×h formula XI; In Formula XI: Ar represents the cross-sectional design area of the concrete beam specimen; b represents the cross-sectional design width of the concrete beam specimen; h represents the cross-sectional design height of the concrete beam specimen.

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