A design method for seawater and sea sand concrete beams with FRP-stainless steel hybrid reinforcement

Abstract

The present invention belongs to the field of structural engineering technology and relates to a design method for FRP-stainless steel hybrid reinforced seawater and sea sand concrete beams, comprising inputting a design bending moment, preliminarily selecting cross-sectional dimensions and material properties; determining whether the area of ​​the stainless steel bars in the compression zone is known, and if so, calculating it; if not, calculating, selecting, and ensuring, and; verifying whether the failure mode satisfies the requirements of appropriate reinforcement failure, whether the bending bearing capacity meets the requirements, and whether the ductility meets the requirements of the specification, and ensuring that the area ratio is within a reasonable range; and finally obtaining a more reasonable reinforcement area and outputting the result. The present invention takes into account that FRP bars are not used as compression bars, and therefore stainless steel bars are configured in the compression zone, and proposes a design method suitable for this form, which can not only effectively solve the problem of steel corrosion in marine service environments, but also ensure high bending bearing capacity and ductility.

Description

Technical Field

[0001] The invention relates to a design method for a seawater and sea sand concrete beam with FRP-stainless steel mixed reinforcement, and belongs to the technical field of structural engineering. Background Art

[0002] In marine engineering construction, the use of seawater-sand concrete not only conserves natural resources and effectively alleviates river sand shortages and freshwater depletion, but also leverages the advantages of geographical location, facilitating local material availability and shortening construction periods. However, the presence of corrosive ions in seawater-sand concrete can cause corrosion of steel bars, thus affecting the durability of the structure.

[0003] Fiber-reinforced polymer (FRP) is a new building material composed of various fibers bonded together through a resin matrix, then extruded and drawn through specialized dies. Its lightweight, high strength, and corrosion resistance make it an ideal alternative to steel bars in marine engineering construction. However, FRP bars suffer from limitations such as low elastic modulus, anisotropy, and brittle failure in FRP-reinforced concrete structures. Improving the ductility of FRP-reinforced concrete structures is fundamental to their widespread use in marine engineering. Stainless steel bars offer excellent ductility and corrosion resistance, effectively addressing steel corrosion in marine environments while also ensuring structural ductility. However, their widespread use would inevitably lead to high costs, insufficient market supply, and limited specifications.

[0004] Based on this, a hybrid reinforcement form in which stainless steel bars partially replace FRP bars in the tension zone can be used, hoping to further improve ductility while ensuring the bending bearing capacity of the structure. In addition, for safety reasons, the American standard ACI 440.1R-15, the Canadian standard CSA S806-12, and the Chinese standard GB 50608-2020 do not recommend FRP bars as compression bars, so stainless steel bars are configured in the compression zone. In existing research, although some scholars have conducted relevant research on hybrid reinforced concrete beams, such as selecting relevant calculation formulas for theoretical analysis based on experimental data, or re-deriving relevant calculation formulas based on the flat section assumption and internal force balance, there is still a lack of systematic research and systematic design methods, which brings certain difficulties to the design and application of hybrid reinforced concrete beams in actual engineering. Summary of the Invention

[0005] The purpose of the present invention is to provide a design method for seawater and sea sand concrete beams with FRP-stainless steel hybrid reinforcement, which can effectively solve the problem of steel corrosion in marine service environments while ensuring high bending bearing capacity and ductility, thereby ensuring the safety and rationality of hybrid reinforced concrete beams in engineering practice.

[0006] To achieve the above-mentioned objectives and solve the problems existing in existing research, the present invention provides the following solution: a design method for an FRP-stainless steel hybrid reinforced seawater and sea sand concrete beam, wherein the FRP-stainless steel hybrid reinforced seawater and sea sand concrete beam comprises upper longitudinal bars and lower longitudinal bars, wherein the upper longitudinal bars comprise stainless steel bars in a compression zone (compression zone longitudinal bars), and the lower longitudinal bars comprise external FRP bars in a tension zone and stainless steel bars in an internal tension zone (tension zone longitudinal bars). FRP stirrups are provided between the longitudinal bars, and the longitudinal bars and stirrups are surrounded by seawater and sea sand concrete.

[0007] The design method includes inputting the design bending moment, preliminarily selecting the cross-sectional dimensions and material properties, and determining the area of ​​the stainless steel reinforcement in the compression zone. Is it known? If so, calculate If unknown, calculate 、 ;choose 、 , and guarantee 、 ; Verify whether the failure mode meets the requirements of appropriate reinforcement failure and whether the bending bearing capacity meets the requirements , whether the ductility meets the requirements of the specification, and ensure that the area ratio is within a reasonable range; finally, a more reasonable reinforcement area is obtained, and the results are output; among them, is the area of ​​the stainless steel reinforcement in the compression zone; The area where no FRP bars are arranged in the tension zone, but only stainless steel bars are arranged; is the area of ​​the stainless steel reinforcement in the tension zone; is the area of ​​FRP reinforcement in the tension zone; is the design bending moment; is the bending bearing capacity.

[0008] The specific steps include:

[0009] S1 Input design bending moment, preliminarily select cross-section size and material properties;

[0010] The cross-sectional dimension is the cross-sectional height With section width ;

[0011] The material properties are concrete strength grade, ultimate strength of FRP bars in tension zone, , elastic modulus of FRP bars in tension zone , Yield strength of stainless steel bars in tension zone , Elastic modulus of stainless steel bars in tension zone , Yield strength of stainless steel bars in compression zone , Elastic modulus of stainless steel bars in compression zone ;

[0012] S2 Determine the area of ​​stainless steel bars in the compression zone whether it is known;

[0013] If known, use the following formula to calculate :

[0014]

[0015] In the formula, is the coefficient related to the width of the equivalent rectangular stress diagram of concrete; is the prism compressive strength of concrete; is the effective height of the section; is the distance from the force resultant point of the stainless steel reinforcement in the compression zone to the edge of the compression zone;

[0016] If unknown, use the following formula to calculate :

[0017]

[0018] In the formula, is the relative height of the compression zone; is the coefficient related to the height of the equivalent rectangular stress diagram of concrete; is the ultimate compressive strain of concrete.

[0019] Calculate using the following formula :

[0020]

[0021] The concrete equivalent rectangular stress diagram coefficients in the above formulas (2) to (4) and (7) are taken in accordance with GB 50010-2010; the concrete equivalent rectangular stress diagram coefficients and ultimate compressive strain in the above formulas (5) and (6) are taken in accordance with GB 50010-2010;

[0022] S3 Select the area of ​​stainless steel bars in the tension zone , the area of ​​FRP bars in the tension zone , and guarantee 、 ;

[0023] and The selection process should ensure that the diameter of the reinforcement meets market requirements;

[0024] S4 Verify whether the failure mode meets the requirements of appropriate reinforcement failure. If so, verify the bending bearing capacity. If not, reselect the area of ​​stainless steel reinforcement in the tension zone. , the area of ​​FRP bars in the tension zone ;

[0025] The failure mode is predicted using the following formula:

[0026]

[0027] In the formula, is the minimum resistance moment coefficient of the section; is the maximum resistance moment coefficient of the section; is the section resistance moment coefficient;

[0028] The concrete equivalent rectangular stress diagram coefficient and ultimate compressive strain in equations (8) and (9) are taken in accordance with GB 50010-2010;

[0029] S5 Verify whether the bending bearing capacity meets If satisfied, conduct ductility verification; if not satisfied, reselect the area of ​​stainless steel bars in the tension zone. , the area of ​​FRP bars in the tension zone ;

[0030] The bending bearing capacity is predicted using the following formula:

[0031]

[0032] In the formula, is the actual height of the compression zone under bending bearing capacity; is the strain of the stainless steel reinforcement in the compression zone; is the yield strain of the stainless steel reinforcement in the compression zone;

[0033] The concrete equivalent rectangular stress diagram coefficient and ultimate compressive strain in equations (12), (15) to (18) are taken in accordance with GB 50010-2010;

[0034] S6 Verify whether the ductility meets the requirements of the specification. If it does, verify the area ratio. If it does not, reselect the area of ​​the stainless steel bars in the tension zone. , the area of ​​FRP bars in the tension zone ;

[0035] The ductility in step S6 is predicted using the following formula:

[0036]

[0037] In the formula, is the deformation ductility coefficient based on deflection; is the mid-span deflection under bending capacity; is the deflection corresponding to the edge compressive strain of concrete reaching 0.001; is the applied bending moment corresponding to the edge compressive strain of the concrete reaching 0.001.

[0038] Equation (20) described in step S6 is evaluated using CSA S6-19, which states that the limit of ductility for rectangular cross-section beams is is not less than 4, the limit value of ductility of T-section beam is not less than 6;

[0039] S7 verifies whether the area ratio meets the reasonable range. If it does, output the result. If it does not meet the requirements and the area ratio is less than 1, reselect the area of ​​the stainless steel bar in the tension zone. , the area of ​​FRP bars in the tension zone , if it is not satisfied and the area ratio is greater than 2.5, reselect the cross-sectional dimensions and material properties;

[0040] Reasonable range reference literature survey results, using ;

[0041] S8 obtains a more reasonable reinforcement area and outputs the results.

[0042] The formula (8) in step S4 is the boundary failure between under-reinforcement and appropriate reinforcement, that is, the FRP bars in the tension zone are broken, and the concrete in the compression zone is crushed; the formula (9) is the boundary failure between over-reinforcement and appropriate reinforcement, that is, the stainless steel bars in the tension zone yield, and the concrete in the compression zone is crushed.

[0043] Formula (10) in step S4 is the section resistance moment coefficient obtained from the design bending moment; Formula (11) requires that the section resistance moment coefficient obtained from the design bending moment should be between the minimum value and the maximum value to meet the requirements of appropriate reinforcement failure.

[0044] In step S5, equations (13) to (16) are used to calculate the stress of the FRP reinforcement in the tension zone; equation (17) is used to calculate the actual height of the compression zone under the bending bearing capacity; and equation (18) is used to calculate the strain of the stainless steel reinforcement in the compression zone.

[0045] The formula (19) in step S5 requires , in order to ensure that the carrying capacity meets the requirements.

[0046] The beneficial effects of the present invention are as follows:

[0047] (1) A mixed reinforcement form of FRP bars and stainless steel bars is adopted. These two types of bars have simple processing technology and can ensure both bending bearing capacity and ductility. At the same time, it effectively solves the problem of steel bar corrosion in the marine service environment while ensuring higher bending bearing capacity and ductility.

[0048] (2) While fully utilizing the high strength and high rust resistance of FRP bars, it also fully utilizes the high ductility and high rust resistance of stainless steel bars, achieving complementary advantages and a strong combination.

[0049] (3) The failure mode and flexural bearing capacity calculation of hybrid reinforced concrete beams considering the contribution of stainless steel bars in the compression zone are significantly improved in prediction effect and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural schematic diagram of a mixed reinforced seawater and sea sand concrete beam according to the present invention.

[0051] Figure 2 It is a schematic cross-sectional view of a mixed reinforced seawater and sea sand concrete beam according to the present invention.

[0052] Figure 3 It is a design module diagram of the mixed reinforced seawater and sea sand concrete beam of the present invention.

[0053] Figure 4 This is a design flow chart of mixed reinforced seawater and sea sand concrete beams according to the present invention.

[0054] Among them, 1 is the stainless steel bar in the compression zone, 2 is the FRP bar in the external tension zone, 3 is the stainless steel bar in the internal tension zone, and 4 is the FRP stirrup. DETAILED DESCRIPTION

[0055] The present invention will be further described below with reference to the accompanying drawings and by introducing a design example of a mixed reinforced concrete beam.

[0056] Example 1

[0057] A design method for seawater and sea sand concrete beams with FRP-stainless steel hybrid reinforcement, such as Figure 1 and Figure 2 As shown, the mixed reinforced seawater and sea sand concrete beam includes upper and lower longitudinal bars of the beam, the upper longitudinal bars include stainless steel bars in the compression zone (compression zone longitudinal bars), and the lower longitudinal bars include FRP bars in the external tension zone and stainless steel bars in the internal tension zone (tension zone longitudinal bars). FRP stirrups are provided between the longitudinal bars, and the longitudinal bars and stirrups are filled with seawater and sea sand concrete.

[0058] Figure 3 This is the design module diagram of mixed reinforced seawater and sea sand concrete beams, which can be divided into four modules, namely module 1 (input module), module 2 (reinforcement module), module 3 (verification module), and module 4 (output module).

[0059] Figure 4 This is the design flow chart of mixed reinforced seawater and sea sand concrete beams. A design example of mixed reinforced seawater and sea sand concrete beams can be introduced for further explanation.

[0060] The basic situation of the design example is shown in Table 1.

[0061] Table 1 Basic information of the design example

[0062]

[0063] The design method comprises the following steps:

[0064] S1 Input design bending moment, preliminarily select section size and material properties, for easy comparison, , the selected cross-sectional dimensions and material properties are the same as those in Table 1;

[0065] S2 When the area of ​​stainless steel reinforcement in the compression zone When it is known, , , assuming that a single layer of stainless steel bars is arranged in the tension zone, then , , ;

[0066] Calculate using the following formula :

[0067]

[0068] In the formula, is the coefficient related to the width of the equivalent rectangular stress diagram of concrete; is the prism compressive strength of concrete; is the effective height of the section; It is the distance from the resultant force point of the stainless steel reinforcement in the compression zone to the edge of the compression zone.

[0069] The concrete equivalent rectangular stress diagram coefficients in formulas (2) to (4) are taken in accordance with GB 50010-2010;

[0070] get ;

[0071] S3 in near , but not greater than Under the principle of , and follow Sure ;

[0072] and The selection process should ensure that the diameter of the reinforcement meets market requirements;

[0073] S4 Verify whether the failure mode meets the requirements of appropriate reinforcement failure. If so, verify the bending bearing capacity. If not, reselect the area of ​​stainless steel reinforcement in the tension zone. , the area of ​​FRP bars in the tension zone ;

[0074] The failure mode is predicted using the following formula:

[0075]

[0076] In the formula, is the coefficient related to the height of the equivalent rectangular stress diagram of concrete; is the minimum resistance moment coefficient of the section; is the maximum resistance moment coefficient of the section; is the section resistance moment coefficient.

[0077] Formula (8) is the limit failure of under-reinforcement and appropriate reinforcement, that is, the FRP reinforcement in the tension zone breaks, and the concrete in the compression zone is crushed; Formula (9) is the limit failure of over-reinforcement and appropriate reinforcement, that is, the stainless steel reinforcement in the tension zone yields, and the concrete in the compression zone is crushed;

[0078] The concrete equivalent rectangular stress diagram coefficient and ultimate compressive strain in equations (8) and (9) are taken in accordance with GB 50010-2010;

[0079] Formula (10) is the section resistance moment coefficient obtained from the design bending moment; Formula (11) requires that the section resistance moment coefficient obtained from the design bending moment should be between the minimum and maximum values ​​to meet the requirements of proper reinforcement failure.

[0080] The failure mode is obtained as reinforcement failure;

[0081] S5 Verify whether the bending bearing capacity meets If satisfied, conduct ductility verification; if not satisfied, reselect the area of ​​stainless steel bars in the tension zone. , the area of ​​FRP bars in the tension zone ;

[0082] The bending bearing capacity is predicted using the following formula:

[0083]

[0084] In the formula, is the actual height of the compression zone under bending bearing capacity; is the strain of the stainless steel reinforcement in the compression zone; is the yield strain of the stainless steel reinforcement in the compression zone.

[0085] The concrete equivalent rectangular stress diagram coefficient and ultimate compressive strain in equations (12), (15) to (18) are taken in accordance with GB 50010-2010;

[0086] Formulas (13) to (16) are used to calculate the stress of the FRP reinforcement in the tension zone; Formula (17) is used to calculate the actual height of the compression zone under the bending bearing capacity; Formula (18) is used to calculate the strain of the stainless steel reinforcement in the compression zone;

[0087] The formula (19) requires , in order to ensure that the carrying capacity meets the requirements;

[0088] get , an increase of 18.28% compared to before design;

[0089] S6 Verify whether the ductility meets the requirements of the specification. If it does, verify the area ratio. If it does not, reselect the area of ​​the stainless steel bars in the tension zone. , the area of ​​FRP bars in the tension zone ;

[0090] The ductility is predicted using the following formula:

[0091]

[0092] In the formula, is the deformation ductility coefficient based on deflection; is the mid-span deflection under bending capacity; is the deflection corresponding to the edge compressive strain of concrete reaching 0.001; is the applied bending moment corresponding to the edge compressive strain of the concrete reaching 0.001.

[0093] The formula (20) is evaluated using CSA S6-19, which is the limit of ductility of rectangular cross-section beams. is not less than 4;

[0094] get ;

[0095] S7 verifies whether the area ratio meets the reasonable range. If it does, output the result. If it does not meet the requirements and the area ratio is less than 1, reselect the area of ​​the stainless steel bar in the tension zone. , the area of ​​FRP bars in the tension zone , if it is not satisfied and the area ratio is greater than 2.5, reselect the cross-sectional dimensions and material properties;

[0096] At this time ,satisfy ;

[0097] S8 obtains a more reasonable reinforcement area and outputs the result;

[0098] The corresponding output result is that two GFRP bars with a diameter of 20 mm and two stainless steel bars with a diameter of 18 mm are configured in the tension zone;

[0099] Similarly, when the area of ​​the stainless steel reinforcement in the compression zone is If unknown, , assuming that double-layer stainless steel bars are arranged in the tension zone, then , , ;

[0100] Calculate using the following formula :

[0101]

[0102] In the formula, is the relative height of the compression zone; is the coefficient related to the height of the equivalent rectangular stress diagram of concrete; is the ultimate compressive strain of concrete.

[0103] The concrete equivalent rectangular stress diagram coefficient and ultimate compressive strain in equations (5) and (6) are taken in accordance with GB 50010-2010;

[0104] At the same time, the following formula is used to calculate :

[0105]

[0106] The concrete equivalent rectangular stress diagram coefficient in formula (7) is taken in accordance with GB 50010-2010;

[0107] get ;

[0108] exist near , but not greater than Under the principle of , and follow Sure ;

[0109] and The selection process should ensure that the diameter of the reinforcement meets market requirements;

[0110] The failure mode is obtained as reinforcement failure;

[0111] get , an increase of 25.43% compared to before design;

[0112] get ;

[0113] At this time ,satisfy ;

[0114] The corresponding output result is that four GFRP bars with a diameter of 22 mm and four stainless steel bars with a diameter of 16 mm are configured in the tension zone.

Claims

1. A design method for seawater and sea sand concrete beams with FRP-stainless steel hybrid reinforcement, characterized by: The concrete beam comprises upper longitudinal reinforcement and lower longitudinal reinforcement, the upper longitudinal reinforcement comprises stainless steel reinforcement (1) in a compression zone, the lower longitudinal reinforcement comprises FRP reinforcement (2) in an external tension zone and stainless steel reinforcement (3) in an internal tension zone, FRP stirrups (4) are provided between the longitudinal reinforcements, and the longitudinal reinforcements and stirrups are surrounded by seawater and sea sand concrete; The design method includes inputting the design bending moment, preliminarily selecting the cross-sectional dimensions and material properties, and determining the area of ​​the stainless steel reinforcement in the compression zone. Is it known? If so, calculate If unknown, calculate 、 ;choose 、 , and guarantee 、 ; Verify whether the failure mode meets the requirements of appropriate reinforcement failure and whether the bending bearing capacity meets the requirements , whether the ductility meets the requirements of the specification, and ensure that the area ratio is within a reasonable range; finally, a more reasonable reinforcement area is obtained, and the results are output; among them, is the area of ​​the stainless steel reinforcement in the compression zone; The area where no FRP bars are arranged in the tension zone, but only stainless steel bars are arranged; is the area of ​​the stainless steel reinforcement in the tension zone; is the area of ​​FRP reinforcement in the tension zone; is the design bending moment; is the bending bearing capacity; The specific steps include: S1: Input design bending moment, preliminarily select section size and material properties; The cross-sectional dimension is the cross-sectional height With section width ; The material properties are concrete strength grade, ultimate strength of FRP bars in tension zone , elastic modulus of FRP bars in tension zone , Yield strength of stainless steel bars in tension zone , Elastic modulus of stainless steel bars in tension zone , Yield strength of stainless steel bars in compression zone , Elastic modulus of stainless steel bars in compression zone ; S2: Determine the area of ​​stainless steel bars in the compression zone whether it is known; If known, use the following formula to calculate : ， In the formula, is the coefficient related to the width of the equivalent rectangular stress diagram of concrete; is the prism compressive strength of concrete; is the effective height of the section; is the distance from the stainless steel reinforcement in the compression zone to the edge of the compression zone; If unknown, use the following formula to calculate : ， In the formula, is the relative height of the compression zone; is the coefficient related to the height of the equivalent rectangular stress diagram of concrete; is the ultimate compressive strain of concrete; Calculate using the following formula : ， The concrete equivalent rectangular stress diagram coefficients in the above formulas (2) to (4) and (7) are taken in accordance with GB 50010-2010; the concrete equivalent rectangular stress diagram coefficients and ultimate compressive strain in the above formulas (5) and (6) are taken in accordance with GB 50010-2010; S3: Select the area of ​​stainless steel reinforcement in the tension zone , the area of ​​FRP bars in the tension zone , and guarantee 、 ; and The selection process should ensure that the diameter of the reinforcement meets market requirements; S4: Verify whether the failure mode meets the requirements of appropriate reinforcement failure. If so, verify the bending bearing capacity. If not, reselect the area of ​​stainless steel reinforcement in the tension zone. , the area of ​​FRP bars in the tension zone ; The failure mode is predicted using the following formula: ， In the formula, is the minimum resistance moment coefficient of the section; is the maximum resistance moment coefficient of the section; is the section resistance moment coefficient; The concrete equivalent rectangular stress diagram coefficient and ultimate compressive strain in equations (8) and (9) described in step S4 are taken in accordance with GB50010-2010; S5: Verify whether the bending bearing capacity is met If satisfied, conduct ductility verification; if not satisfied, reselect the area of ​​stainless steel bars in the tension zone. , the area of ​​FRP bars in the tension zone ; The bending bearing capacity is predicted using the following formula: ， In the formula, is the actual height of the compression zone under bending bearing capacity; is the strain of the stainless steel reinforcement in the compression zone; is the yield strain of the stainless steel reinforcement in the compression zone; The concrete equivalent rectangular stress diagram coefficient and ultimate compressive strain in equations (12), (15) to (18) are taken in accordance with GB50010-2010; S6: Verify whether the ductility meets the requirements of the specification. If it does, verify the area ratio. If it does not, reselect the area of ​​the stainless steel bars in the tension zone. , the area of ​​FRP bars in the tension zone ; The ductility is predicted using the following formula: ， In the formula, is the deformation ductility coefficient based on deflection; is the mid-span deflection under bending capacity; is the deflection corresponding to the edge compressive strain of concrete reaching 0.001; is the applied bending moment corresponding to the concrete edge compressive strain reaching 0.001; The formula (20) is evaluated using CSA S6-19, which is the limit of ductility of rectangular cross-section beams. is not less than 4, the limit value of ductility of T-section beam is not less than 6; S7: Verify whether the area ratio meets the reasonable range. If it does, output the result. If it does not meet the requirements and the area ratio is less than 1, reselect the area of ​​the stainless steel bar in the tension zone. , the area of ​​FRP bars in the tension zone , if it is not satisfied and the area ratio is greater than 2.5, reselect the cross-sectional dimensions and material properties; The reasonable range is based on the results of literature research. ; S8: Obtain a more reasonable reinforcement area and output the results.

2. The design method of a FRP-stainless steel hybrid reinforced seawater and sea sand concrete beam according to claim 1, characterized in that: The formula (8) in step S4 is the boundary failure between under-reinforcement and appropriate reinforcement, that is, the FRP bars in the tension zone are broken, and the concrete in the compression zone is crushed; the formula (9) is the boundary failure between over-reinforcement and appropriate reinforcement, that is, the stainless steel bars in the tension zone yield, and the concrete in the compression zone is crushed.

3. The design method of a seawater and sea sand concrete beam with FRP-stainless steel hybrid reinforcement according to claim 1, characterized in that: Formula (10) in step S4 is the section resistance moment coefficient obtained from the design bending moment; Formula (11) requires that the section resistance moment coefficient obtained from the design bending moment should be between the minimum value and the maximum value to meet the requirements of appropriate reinforcement failure.

4. The design method of a seawater and sea sand concrete beam with FRP-stainless steel hybrid reinforcement according to claim 1, characterized in that: In step S5, equations (13) to (16) are used to calculate the stress of the FRP reinforcement in the tension zone; equation (17) is used to calculate the actual height of the compression zone under the bending bearing capacity; and equation (18) is used to calculate the strain of the stainless steel reinforcement in the compression zone.

5. The design method of a seawater and sea sand concrete beam with FRP-stainless steel hybrid reinforcement according to claim 1, characterized in that: The formula (19) in step S5 requires , in order to ensure that the carrying capacity meets the requirements.

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