Steel-concrete composite structure continuous bridge and reinforcing design method suitable for steel-concrete composite structure continuous bridge

Abstract

The invention discloses a steel-concrete composite structure continuous bridge and a reinforcement design method suitable for the steel-concrete composite structure continuous bridge, and the reinforcement design method suitable for the steel-concrete composite structure continuous bridge comprises the following steps: S10, detecting the bridge to obtain a detection evaluation result of the bridge; s20, on the basis of the detection and evaluation result, a bridge reinforcing scheme is obtained in combination with use factors of the bridge; s30, on the basis of the bridge reinforcement scheme, re-checking calculation is conducted through modeling, and structural safety reserve is judged; and S40, based on the step S30, if the structure safety reserve does not meet the safety value, the reinforcing design parameters are adjusted, and re-checking is repeated until the structure safety reserve meets the safety value. The continuous bridge with the steel-concrete composite structure is reinforced based on the reinforcement design method. Therefore, the problems that the bearing capacity of the continuous bridge of the steel-concrete composite structure is insufficient in the bearing capacity limit state and the crack width exceeds the limit in the normal use limit state are solved, the bearing performance of the bridge is improved, and smooth and safe traffic operation is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of steel-concrete continuous bridges, and in particular to a steel-concrete composite structure continuous bridge and a reinforcement design method suitable for the steel-concrete composite structure continuous bridge. Background Art

[0002] The steel-concrete composite structure continuous bridge is a bridge whose components can be prefabricated. Through the connectors, the two materials are subjected to force synergistically, giving full play to the material properties of steel and concrete. In areas with inconvenient transportation, such as mountainous areas, there are certain difficulties in the transportation of materials and the entry of large construction equipment. The steel-concrete composite structure continuous bridge reduces the requirements for transportation conditions by transporting prefabricated components to the construction site and then splicing them. It conforms to the construction concept of assembled, green, low-carbon, sustainable, easy to maintain, and intelligent bridge construction.

[0003] Steel-concrete composite continuous bridges also have some defects during use, for example:

[0004] First, the existing carrying capacity of the bridge is limited and cannot meet the requirements of the current traffic flow and load standards. Under long-term and high-intensity use, the safety and stability of the bridge structure face severe tests. At this time, it is necessary to reinforce the built bridges.

[0005] Secondly, in the force system of steel-concrete composite beams, the state where the concrete wing is compressed and the steel beam is tensile is considered to be the most ideal force mode, because it can give full play to the mechanical properties of the two materials and achieve efficient force transmission and distribution, thus providing a strong guarantee for the overall stability of the structure. However, for continuous beam structures, in the negative moment zone of the mid-support, due to the change in the moment direction, it is inevitable that the concrete wing will be tensile and the steel beam will be compressed. When this causes the bridge to bend, crack, and other defects, it is necessary to reinforce the bridge.

[0006] Therefore, in view of the current status of the use of steel-concrete composite continuous bridges, it is necessary to propose a reinforcement design method suitable for steel-concrete composite continuous bridges. Summary of the invention

[0007] The object of the present invention is to provide a steel-concrete composite structure continuous bridge and a reinforcement design method suitable for the steel-concrete composite structure continuous bridge to solve the above-mentioned problems.

[0008] The present invention is achieved through the following technical solutions:

[0009] In a first aspect, the present invention provides a reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure, comprising the following steps:

[0010] S10: inspect the bridge and obtain inspection and evaluation results of the bridge;

[0011] S20: Based on the test and evaluation results and combined with the bridge usage factors, a bridge reinforcement plan is obtained;

[0012] S30: Based on the bridge reinforcement plan, the structural safety reserve is determined by performing verification calculations through modeling;

[0013] S40: Based on S30, if the structural safety reserve does not meet the safety value, adjust the reinforcement design parameters and repeat the review until the structural safety reserve meets the safety value.

[0014] In one possible design, S40 includes the following steps:

[0015] S41: Based on S30, obtain structural analysis results;

[0016] S42: Based on the structural analysis results, if the safety value is met after reinforcement, the bridge reinforcement plan is available; if the safety value is not met after reinforcement, the reinforcement design parameters are adjusted and repeatedly reviewed until the structural safety reserve meets the safety value;

[0017] Among them, S42 includes:

[0018] S100: If the bending bearing capacity of the positive section of the bridge before reinforcement does not meet the safety value, based on the reinforcement scheme of S20, the bearing capacity of the positive bending moment section and the negative bending moment section after reinforcement shall be verified respectively;

[0019] S200: If the crack width of the concrete slab of the bridge before reinforcement does not meet the safety value, based on the reinforcement scheme of S20, the crack width of the negative bending moment section after reinforcement is verified.

[0020] S300: In S100 and S200, if the calculation results do not meet the safety value, adjust the reinforcement design parameters and repeat the review until the structural safety reserve meets the safety value.

[0021] In a possible design, in S100, in the positive moment action section, when the plastic neutral axis is inside the concrete slab, all steel beams are under tension and evenly reach the design value of the steel tensile strength, the positive cross-section compressive bearing capacity of the reinforced bridge should meet the requirements of (1-1), (1-2), and (1-3):

[0022] γ0M d ≤ b eff x1f cd y1+Aη a f ad y2 (1-1)

[0023] A0 ad0 +η a Aad =b eff x1f cd (1-2)

[0024]

[0025] Where:

[0026] y0—structural importance coefficient of the reinforced bridge;

[0027] M d —Design value of bending moment after bridge reinforcement;

[0028] b eff —Effective width of concrete slab;

[0029] x1—Equivalent compression zone height of stress diagram of compression zone of cross section;

[0030] f cd —Design value of compressive strength of concrete slab;

[0031] A—cross-sectional area of ​​reinforced steel plate;

[0032] η a —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1;

[0033] f ad —Design value of strength of reinforced steel plate;

[0034] A0—cross-sectional area of ​​steel beam before reinforcement;

[0035] f ad0 —Design value of steel beam strength before reinforcement;

[0036] β—Ratio of the height of the rectangular stress diagram in the compression zone of the cross section to the height of the actual compression zone, which is determined according to the "Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" (JTG3362-2018);

[0037] ε cu —The ultimate compressive strain of concrete when the cross section is subjected to non-uniform compression. When the concrete strength grade is C50 or below, take ε cu =0.0033; when the concrete strength grade is C80, take ε cu =0.003; the intermediate strength level is obtained by linear interpolation;

[0038] h—total height of the steel-concrete composite bridge;

[0039] ε a,0 —When considering the influence of secondary force, the hysteresis strain of the reinforced steel plate is calculate;

[0040] E a —Elastic modulus of the reinforcement steel plate;

[0041] M k —Standard value of bending moment acting on the cross section of steel-concrete composite bridge before reinforcement;

[0042] y1—the distance between the resultant force of the cross-sectional stress of the steel beam before reinforcement and the resultant force of the cross-sectional stress of the concrete compression zone;

[0043] y2—The distance between the resultant force of the reinforced steel plate and the resultant force of the cross-sectional stress in the compression zone of the concrete.

[0044] In a possible design, in S100, in the positive moment action section, when the plastic neutral axis is inside the steel beam, the steel beam portion close to the concrete slab is under compression, and the portion away from the concrete slab is under tension, and the steel compressive and tensile strength design values ​​are evenly reached. The compressive bearing capacity of the positive section of the reinforced bridge should meet the requirements of (2-1) and (2-2):

[0045] γ0M d ≤ b eff h c f cd y5+Aη a f ad y4+A c0 f ad0 y3 (2-1)

[0046]

[0047] Where:

[0048] M d —Design value of bending moment after bridge reinforcement;

[0049] b eff —Effective width of concrete slab;

[0050] h c —Total thickness of concrete slab;

[0051] f cd —Design value of compressive strength of concrete slab;

[0052] A—cross-sectional area of ​​reinforced steel plate;

[0053] η a —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1;

[0054] f ad —Design value of strength of reinforced steel plate;

[0055] A c0—Cross-sectional area of ​​the steel beam in compression zone;

[0056] f ad0 —Design value of steel beam strength before reinforcement;

[0057] y3—the distance from the centroid of the cross section of the steel beam in tension to the centroid of the cross section of the steel beam in compression;

[0058] y4—the distance from the centroid of the steel beam section in the tension zone to the centroid of the reinforced steel plate section;

[0059] y5—The distance from the centroid of the steel beam section in the tension zone to the centroid of the concrete slab section.

[0060] In a possible design, in S100, in the negative moment section, the compressive bearing capacity of the positive section of the reinforced bridge should comply with the provisions of (3-1), (3-2), (3-3), and (3-4):

[0061] γ0M d ≤A cf η cf f cf y9+A s f sd y8+Aη a f ad y7+(A0-A c0 )f ad0 y6 (3-1)

[0062]

[0063] Where:

[0064] A cf —Cross-sectional area of ​​carbon fiber composite;

[0065] f cf —Design value of tensile strength of carbon fiber composites;

[0066] M d —Design value of bending moment after bridge reinforcement;

[0067] η cf —When considering the influence of secondary force, the reduction factor of the tensile strength of carbon fiber composite material cannot reach the calculated value, η cf ≤1;

[0068] A s —The cross-sectional area of ​​longitudinal reinforcement within the effective width of the concrete slab in the negative bending moment zone;

[0069] f sd —Design value of longitudinal reinforcement tensile strength;

[0070] A—cross-sectional area of ​​reinforced steel plate;

[0071] ηa —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1;

[0072] f ad —Design value of strength of reinforced steel plate;

[0073] A c0 —Cross-sectional area of ​​the steel beam in compression zone;

[0074] f ad0 —Design value of steel beam strength before reinforcement;

[0075] x2—the distance from the neutral axis of the cracked section to the top of the beam;

[0076] h—total height of the steel-concrete composite bridge;

[0077] ε cf —The tensile strain design value of carbon fiber composite is 0.007;

[0078] ε cf,0 —Hysteresis strain of carbon fiber composites when considering the influence of secondary forces;

[0079] E s —elastic modulus of longitudinal reinforcement;

[0080] E a —Elastic modulus of the reinforcement steel plate;

[0081] M k —Standard value of bending moment acting on the cross section of steel-concrete composite bridge before reinforcement;

[0082] h0—effective compression height of the section;

[0083] y6—the distance from the centroid of the cross section of the steel beam in compression to the centroid of the cross section of the steel beam in tension;

[0084] y7—the distance from the centroid of the cross section of the steel beam in the compression zone to the centroid of the cross section of the reinforced steel plate;

[0085] y8—the distance from the centroid of the steel beam compression zone section to the centroid of the longitudinal reinforcement section;

[0086] y9—The distance from the centroid of the steel beam cross section in the compression zone to the top of the steel-concrete composite beam.

[0087] In one possible design, in S200, the maximum crack width W of the concrete in the negative moment section under the serviceability limit state is cr It shall comply with the provisions of (4-1), (4-2) and (4-3):

[0088]

[0089] Where:

[0090] W cr —The maximum crack width of the concrete in the negative moment section under the serviceability limit state;

[0091] E cf —Elastic modulus of carbon fiber composites;

[0092] C1—Steel surface shape coefficient, for plain steel bars, C1=1.40; for ribbed steel bars, C1=1.00; for epoxy resin

[0093] Grease-coated ribbed steel bars, C1 = 1.15;

[0094] C2—Long-term effect coefficient, M l and M s They are quasi-permanent combination and frequent combination

[0095] The calculated design value of bending moment (or design value of axial force);

[0096] C3—coefficient related to the stress properties of the member. For continuous bridges with steel-concrete composite structures, C3=1.0;

[0097] c—thickness of the concrete cover of the outermost row of longitudinal tensile reinforcements in the concrete bridge deck. When c>50mm, take 50mm;

[0098] d—diameter of longitudinal tensile reinforcement;

[0099] σ s —Equivalent stress of steel bars;

[0100] E s —elastic modulus of longitudinal reinforcement;

[0101] ρ te —Equivalent reinforcement ratio of longitudinal reinforcement, 0.01≤ρ te ≤0.1;

[0102] A s —The cross-sectional area of ​​longitudinal reinforcement within the effective width of the concrete slab in the negative bending moment zone;

[0103] M d —Design value of bending moment after bridge reinforcement;

[0104] f ad0 —Design value of steel beam strength before reinforcement;

[0105] W np0 —Plastic section moment of inertia of the steel beam section before reinforcement;

[0106] f ad —Design value of strength of reinforced steel plate;

[0107] W np —Moment of inertia of the plastic section of the reinforced steel plate;

[0108] y 10 —The distance from the centroid of the longitudinal reinforcement section to the plastic neutral axis of the steel-concrete composite structural beam;

[0109] y 11 —The distance from the plastic neutral axis of a pure steel beam to the plastic neutral axis of a steel-concrete composite structural beam.

[0110] In a possible design, in S10, the inspection items include appearance inspection, nondestructive testing and load testing, and the inspection and evaluation results of the bridge include the damage condition, bearing capacity and actual stress performance of the bridge.

[0111] In one possible design, in S20, the bridge reinforcement plan includes the selection of reinforcement methods, the determination of reinforcement materials, the formulation of construction techniques and the design of reinforcement structures, and the design of reinforcement structures includes the design of anchor length and spacing.

[0112] In a possible design, in S30, when modeling, actual test parameters are input to recalculate the bearing capacity of the bridge under the existing disease condition; when judging the structural safety reserve, a safety value is selected based on the original design standard of the bridge and / or the current bridge design specification.

[0113] In a second aspect, the present invention provides a continuous bridge of a steel-concrete composite structure, which is reinforced based on the reinforcement design method applicable to the continuous bridge of a steel-concrete composite structure.

[0114] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0115] Solve the problems of insufficient bearing capacity of steel-concrete composite structure continuous bridges under the ultimate bearing capacity state and excessive crack width under the normal use limit state, improve the bearing performance of the bridge, and ensure smooth and safe traffic operation.

[0116] Relevant formula groups are provided, and staff can select the corresponding formula group for calculation according to the specific conditions of the bridge. The operation is simple and the efficiency of review is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0117] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0118] Figure 1 The figure is a flow chart of a reinforcement design method applicable to continuous bridges with steel-concrete composite structures. DETAILED DESCRIPTION

[0119] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0120] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, materials, or methods are not specifically described.

[0121] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0122] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0123] Embodiment 1:

[0124] like Figure 1 As shown, a reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure includes the following steps:

[0125] S10: inspect the bridge and obtain inspection and evaluation results of the bridge;

[0126] S20: Based on the test and evaluation results and combined with the bridge usage factors, a bridge reinforcement plan is obtained;

[0127] S30: Based on the bridge reinforcement plan, the structural safety reserve is determined by performing verification calculations through modeling;

[0128] S40: Based on S30, if the structural safety reserve does not meet the safety value, adjust the reinforcement design parameters and repeat the review until the structural safety reserve meets the safety value.

[0129] For the reinforcement design method applicable to the continuous bridge of steel-concrete composite structure, in S10, not only the actual current condition of the bridge can be obtained so that the staff can determine the existing defects of the bridge, but also various data of the bridge can be collected to provide data support for the modeling in S30.

[0130] In S20, based on the inspection and evaluation results of S10, the actual current condition of the bridge is confirmed, and a bridge reinforcement plan is formulated in combination with the use of the bridge, such as the use requirements of the bridge, traffic conditions, etc. Based on this, the bridge is reinforced and renovated through the bridge reinforcement plan to improve the bridge's bearing capacity and ensure smooth and safe traffic operation.

[0131] In S30, the actual bridge data obtained in S10 is used as the basis for modeling. After modeling, not only can the existing bearing capacity of the bridge be analyzed and calculated, and the actual condition of the bridge can be comprehensively analyzed and obtained, but also the bridge reinforcement scheme can be reviewed and calculated to determine the feasibility of the bridge reinforcement scheme.

[0132] It is worth noting that in S30, any suitable existing structural analysis software can be used for modeling. At the same time, for the safety value, the original design standard of the bridge and the current bridge design specification are used as the benchmark to judge the structural safety reserve. Among them, the original design standard refers to the bridge design specification when the bridge is built, and in general, the safety value is based on the provisions of the current bridge design specification, among which the bridge design specification includes but is not limited to the "General Specification for Highway Bridge and Culvert Design" (JTG D60-2015), "Highway Reinforced Concrete and Prestressed Reinforced Concrete Bridge and Culvert Design Specification" (JTG 3362-2018), "Highway Steel Structure Bridge Design Specification" (JTG D64-2015), "Highway Steel-Concrete Composite Bridge Design and Construction Specification" (JTG / T D64-01-2015).

[0133] In S40, based on the judgment result of S30, that is, whether the structural safety reserve of the bridge meets the requirements, it is determined whether to adjust the bridge reinforcement plan obtained in S20 to ensure the safety of the bridge after reinforcement.

[0134] In a possible implementation, in S10, the inspection items include appearance inspection, non-destructive testing and load testing, and the inspection and evaluation results of the bridge include the damage, bearing capacity and actual stress performance of the bridge. It is easy to understand that if necessary, the staff can add inspection items and evaluation result items to increase the richness of the data, so as to understand and grasp the actual condition of the bridge from all aspects and angles, so as to make the bridge reinforcement plan formulated in S20 better adapted to the bridge.

[0135] In a possible implementation, in S20, the bridge reinforcement scheme includes the selection of reinforcement methods, the determination of reinforcement materials, the formulation of construction processes and the design of reinforcement structures, and the design of reinforcement structures includes the design of anchor lengths and spacings. Based on the above design scheme, according to the detection and evaluation results of S10, a suitable reinforcement scheme is formulated. It is easy to understand that, if necessary, the bridge reinforcement scheme may also include any other suitable reinforcement items, and the present invention does not impose any limitation on this.

[0136] In a possible implementation, in S30, when modeling, actual detection parameters are input to check and calculate the bearing capacity of the bridge under the existing disease condition; when judging the structural safety reserve, the safety value is selected based on the original design standard of the bridge and / or the current bridge design specification. Based on the above design scheme, the actual detection parameters are the bridge parameters obtained in S10 to improve the quality of modeling. For the safety value, it is generally selected from the current bridge design specification.

[0137] In a possible implementation, S40 includes the following steps:

[0138] S41: Based on S30, obtain structural analysis results;

[0139] S42: Based on the structural analysis results, if the safety value is met after reinforcement, the bridge reinforcement plan can be used; if the safety value is not met after reinforcement, adjust the reinforcement design parameters and repeat the review until the structural safety reserve meets the safety value.

[0140] Based on the above design scheme, that is, according to the structural analysis results, it is determined whether the reinforcement design parameters need to be adjusted. If the reinforcement design parameters need to be adjusted, refer to the formula in Example 2 for review and calculation.

[0141] Embodiment 2:

[0142] This embodiment describes the review calculation based on the embodiment 1, specifically:

[0143] S42 includes:

[0144] S100: If the bending bearing capacity of the positive section of the bridge before reinforcement does not meet the safety value, based on the reinforcement scheme of S20, the bearing capacity of the positive bending moment section and the negative bending moment section after reinforcement shall be verified respectively;

[0145] S200: If the crack width of the concrete slab of the bridge before reinforcement does not meet the safety value, based on the reinforcement scheme of S20, the crack width of the negative bending moment section after reinforcement is verified.

[0146] S300: In S100 and S200, if the calculation results do not meet the safety value, adjust the reinforcement design parameters and repeat the review until the structural safety reserve meets the safety value.

[0147] Based on the above design, the bearing capacity of the bridge is measured by bending resistance and crack width. Specifically:

[0148] If the force is greater than the ultimate bearing capacity of the positive section of the bridge, the bridge will bend. Therefore, the ultimate bearing capacity of the positive section of the bridge is used to measure the bending resistance of the bridge. Furthermore, considering the difference in the properties of steel and concrete, according to the different force directions of different sections of the steel-concrete composite structure continuous bridge, the verification formulas for the ultimate bearing capacity of the positive bending moment section and the ultimate bearing capacity of the negative bending moment section are proposed respectively.

[0149] At the same time, in the negative moment section, the tensile strength of concrete is low. When the tensile force exceeds its tensile limit, the concrete will exit the working state. At this time, the negative moment section will also exit the normal use state. If the tensile force increases again, cracks will appear in the negative moment section of the bridge. The crack width is measured by the maximum crack width of the concrete in the negative moment section of the steel-concrete composite structure continuous bridge under the normal use limit state.

[0150] In addition, since the bridge has been stressed before reinforcement, when considering the later stress of the reinforcement material, the design value of the tensile strength of the material may not reach the design value. The parameter reinforcement steel plate hysteresis strain and the reduction factor of the tensile strength that cannot reach the calculated value are used to consider the influence of secondary stress. Therefore, in order to reduce the secondary stress of the reinforcement material, the automobile load on the continuous bridge of the steel-concrete composite structure should be unloaded during reinforcement to reduce the hysteresis strain of the reinforcement steel plate.

[0151] Among them, for the section of positive bending moment, considering that the concrete compression area is uniform and reaches the design value of concrete compressive strength, and combined with the neutral axis position of the steel-concrete composite section, it is divided into the following two cases: 1. All steel beams are tensile and evenly reach the design value of steel tensile strength; 2. The part of the steel beam close to the concrete slab is compressed, and the part far from the concrete slab is tensile, and the design values ​​of steel compressive and tensile strengths are evenly reached.

[0152] For the first case, that is, in S100, in the positive moment action section, when the plastic neutral axis is inside the concrete slab, all steel beams are under tension and evenly reach the design value of the steel tensile strength, that is, A0f ad0 +Af ad ≤ b eff h c f cd When the cross-section compressive bearing capacity of the reinforced bridge is 1-1, 1-2 and 1-3, the following requirements should be met:

[0153] γ0M d ≤ b eff x1f cd y1+Aη a f ad y2 (1-1)

[0154] A0 ad0 +η a A ad =b eff x1f cd (1-2)

[0155]

[0156] Where:

[0157] y0—structural importance coefficient of the reinforced bridge;

[0158] M d —Design value of bending moment after bridge reinforcement;

[0159] b eff —Effective width of concrete slab;

[0160] x1—Equivalent compression zone height of stress diagram of compression zone of cross section;

[0161] f cd —Design value of compressive strength of concrete slab;

[0162] A—cross-sectional area of ​​reinforced steel plate;

[0163] η a —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1;

[0164] f ad —Design value of strength of reinforced steel plate;

[0165] A0—cross-sectional area of ​​steel beam before reinforcement;

[0166] f ad0 —Design value of steel beam strength before reinforcement;

[0167] β—Ratio of the height of the rectangular stress diagram in the compression zone of the cross section to the height of the actual compression zone, which is determined according to the "Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" (JTG3362-2018);

[0168] ε cu —The ultimate compressive strain of concrete when the cross section is subjected to non-uniform compression. When the concrete strength grade is C50 or below, take ε cu =0.0033; when the concrete strength grade is C80, take ε cu =0.003; the intermediate strength level is obtained by linear interpolation;

[0169] h—total height of the steel-concrete composite bridge;

[0170] ε a,0 —When considering the influence of secondary force, the hysteresis strain of the reinforced steel plate is calculate;

[0171] E a —Elastic modulus of the reinforcement steel plate;

[0172] M k —Standard value of bending moment acting on the cross section of steel-concrete composite bridge before reinforcement;

[0173] y1—the distance between the resultant force of the cross-sectional stress of the steel beam before reinforcement and the resultant force of the cross-sectional stress of the concrete compression zone;

[0174] y2—The distance between the resultant force of the reinforced steel plate and the resultant force of the cross-sectional stress in the compression zone of the concrete.

[0175] For the second case, that is, in S100, in the positive moment action section, when the plastic neutral axis is inside the steel beam, the steel beam is compressed near the concrete slab and tensile away from the concrete slab, and the steel compressive and tensile strengths are uniformly reached, that is, A0f ad0 +Af ad ≥ b eff h c f cd When the compressive bearing capacity of the reinforced bridge cross section is 2-1, 2-2, the following requirements shall be met:

[0176] γ0M d ≤ b eff h c f cd y5+Aη a f ad y4+A c0 f ad0 y3 (2-1)

[0177]

[0178] Where:

[0179] M d —Design value of bending moment after bridge reinforcement;

[0180] b eff —Effective width of concrete slab;

[0181] h c —Total thickness of concrete slab;

[0182] f cd —Design value of compressive strength of concrete slab;

[0183] A—cross-sectional area of ​​reinforced steel plate;

[0184] η a —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1;

[0185] f ad —Design value of strength of reinforced steel plate;

[0186] A c0 —Cross-sectional area of ​​the steel beam under compression;

[0187] f ad0 —Design value of steel beam strength before reinforcement;

[0188] y3—the distance from the centroid of the cross section of the steel beam in tension to the centroid of the cross section of the steel beam in compression;

[0189] y4—the distance from the centroid of the steel beam section in the tension zone to the centroid of the reinforced steel plate section;

[0190] y5—The distance from the centroid of the steel beam section in the tension zone to the centroid of the concrete slab section.

[0191] For the section with negative bending moment, the tensile strength of concrete is relatively low. When the tensile force exceeds its tensile limit, the concrete will exit the working state. When calculating the stress of the steel bar, the principle of equal strain is adopted to treat the reinforcement material as equivalent to the steel bar to calculate the stress of the steel bar of the converted section. Specifically: In S100, in the section with negative bending moment, the compressive bearing capacity of the positive section of the bridge after reinforcement shall comply with the provisions of (3-1), (3-2), (3-3), and (3-4):

[0192] γ0M d ≤A cf η cf f cf y9+A s f sd y8+Aη a f ad y7+(AAc0 )f ad0 y6 (3-1)

[0193]

[0194] Where:

[0195] A cf —Cross-sectional area of ​​carbon fiber composite;

[0196] f cf —Design value of tensile strength of carbon fiber composites;

[0197] M d —Design value of bending moment after bridge reinforcement;

[0198] η cf —When considering the influence of secondary force, the reduction factor of the tensile strength of carbon fiber composite material cannot reach the calculated value, η cf ≤1;

[0199] A s —The cross-sectional area of ​​longitudinal reinforcement within the effective width of the concrete slab in the negative bending moment zone;

[0200] f sd —Design value of longitudinal reinforcement tensile strength;

[0201] A—cross-sectional area of ​​reinforced steel plate;

[0202] η a —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1;

[0203] f ad —Design value of strength of reinforced steel plate;

[0204] A c0 —Cross-sectional area of ​​the steel beam under compression;

[0205] f ad0 —Design value of steel beam strength before reinforcement;

[0206] x2—the distance from the neutral axis of the cracked section to the top of the beam;

[0207] h—total height of the steel-concrete composite bridge;

[0208] ε cf —The tensile strain design value of carbon fiber composite is 0.007;

[0209] ε cf,0 —Hysteresis strain of carbon fiber composites when considering the influence of secondary forces;

[0210] E s—elastic modulus of longitudinal reinforcement;

[0211] E a —Elastic modulus of the reinforcement steel plate;

[0212] M k —Standard value of bending moment acting on the cross section of steel-concrete composite bridge before reinforcement;

[0213] h0—effective compression height of the section;

[0214] y6—the distance from the centroid of the cross section of the steel beam in compression to the centroid of the cross section of the steel beam in tension;

[0215] y7—the distance from the centroid of the cross section of the steel beam in the compression zone to the centroid of the cross section of the reinforced steel plate;

[0216] y8—the distance from the centroid of the steel beam compression zone section to the centroid of the longitudinal reinforcement section;

[0217] y9—The distance from the centroid of the steel beam cross section in the compression zone to the top of the steel-concrete composite beam.

[0218] It should be noted that for the above three situations, in order to prevent the shear brittle failure of the bridge before the normal section failure after reinforcement, the increase in bending bearing capacity should be controlled not to exceed 30%.

[0219] For the crack width, refer to the provisions of the "Highway Reinforced Concrete and Prestressed Concrete Bridge and Culvert Design Code" and calculate it according to the axial tension member, that is, in S200, the maximum crack width W of the concrete in the negative moment section under the normal service limit state cr It shall comply with the provisions of (4-1), (4-2) and (4-3):

[0220]

[0221] Where:

[0222] W cr —The maximum crack width of the concrete in the negative moment section under the serviceability limit state;

[0223] E cf —Elastic modulus of carbon fiber composites;

[0224] C1—Steel surface shape coefficient, for plain steel bars, C1=1.40; for ribbed steel bars, C1=1.00; for epoxy resin

[0225] Grease-coated ribbed steel bars, C1 = 1.15;

[0226] C2—Long-term effect coefficient, M l and M s They are quasi-permanent combination and frequent combination

[0227] The calculated design value of bending moment (or design value of axial force);

[0228] C3—coefficient related to the stress properties of the member. For continuous bridges with steel-concrete composite structures, C3=1.0;

[0229] c—thickness of the concrete cover of the outermost row of longitudinal tensile reinforcements in the concrete bridge deck. When c>50mm, take 50mm;

[0230] d—diameter of longitudinal tensile reinforcement;

[0231] σ s —Equivalent stress of steel bars;

[0232] E s —elastic modulus of longitudinal reinforcement;

[0233] ρ te —Equivalent reinforcement ratio of longitudinal reinforcement, 0.01≤ρ te ≤0.1;

[0234] A s —The cross-sectional area of ​​longitudinal reinforcement within the effective width of the concrete slab in the negative bending moment zone;

[0235] M d —Design value of bending moment after bridge reinforcement;

[0236] f ad0 —Design value of steel beam strength before reinforcement;

[0237] W np0 —Plastic section moment of inertia of the steel beam section before reinforcement;

[0238] f ad —Design value of strength of reinforced steel plate;

[0239] W np —Moment of inertia of the plastic section of the reinforced steel plate;

[0240] y 10 —The distance from the centroid of the longitudinal reinforcement section to the plastic neutral axis of the steel-concrete composite structural beam;

[0241] y 11 —The distance from the plastic neutral axis of a pure steel beam to the plastic neutral axis of a steel-concrete composite structural beam.

[0242] Furthermore, for formula groups (1)-(4), the staff can select the corresponding formula group for re-calculation according to the actual damage condition of the bridge.

[0243] Embodiment 3:

[0244] This embodiment introduces a steel-concrete composite structure continuous bridge based on Embodiments 1 and 2. The steel-concrete composite structure continuous bridge is reinforced based on the reinforcement design method applicable to the steel-concrete composite structure continuous bridge.

[0245] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A reinforcement design method applicable to continuous bridges of steel-concrete composite structures, characterized in that: The following steps are involved: S10: inspect the bridge and obtain inspection and evaluation results of the bridge; S20: Based on the test and evaluation results and combined with the bridge usage factors, a bridge reinforcement plan is obtained; S30: Based on the bridge reinforcement plan, the structural safety reserve is determined by performing verification calculations through modeling; S40: Based on S30, if the structural safety reserve does not meet the safety value, adjust the reinforcement design parameters and repeat the review until the structural safety reserve meets the safety value.

2. The reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure according to claim 1 is characterized in that: S40 includes the following steps: S41: Based on S30, obtain structural analysis results; S42: Based on the structural analysis results, if the safety value is met after reinforcement, the bridge reinforcement plan is available; if the safety value is not met after reinforcement, the reinforcement design parameters are adjusted and repeatedly reviewed until the structural safety reserve meets the safety value; Among them, S42 includes: S100: If the bending bearing capacity of the positive section of the bridge before reinforcement does not meet the safety value, based on the reinforcement scheme of S20, the bearing capacity of the positive bending moment section and the negative bending moment section after reinforcement shall be verified respectively; S200: If the crack width of the concrete slab of the bridge before reinforcement does not meet the safety value, based on the reinforcement scheme of S20, the crack width of the negative bending moment section after reinforcement is verified. S300: In S100 and S200, if the calculation results do not meet the safety value, adjust the reinforcement design parameters and repeat the review until the structural safety reserve meets the safety value.

3. The reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure according to claim 2 is characterized in that: In S100, in the positive moment action section, when the plastic neutral axis is inside the concrete slab, all steel beams are under tension and evenly reach the design value of the steel tensile strength, the positive cross-section compressive bearing capacity of the reinforced bridge shall comply with the provisions of (1-1), (1-2), and (1-3): γ0M d ≤b eff x1f cd y1+An a f ad y2 (1-1)A0f ad0 +n a Af ad =b eff x1f cd (1-2) Where: y0—structural importance coefficient of the reinforced bridge; M d —Design value of bending moment after bridge reinforcement; b eff —Effective width of concrete slab; x1—Equivalent compression zone height of stress diagram of compression zone of cross section; f cd —Design value of compressive strength of concrete slab; A—cross-sectional area of ​​reinforced steel plate; η a —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1; f ad —Design value of strength of reinforced steel plate; A0—cross-sectional area of ​​steel beam before reinforcement; f ad0 —Design value of steel beam strength before reinforcement; β—Ratio of the height of the rectangular stress diagram in the compression zone of the cross section to the height of the actual compression zone, which is determined according to the "Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" (JTG3362-2018); ε cu —The ultimate compressive strain of concrete when the cross section is subjected to non-uniform compression. When the concrete strength grade is C50 or below, take ε cu =0.0033; when the concrete strength grade is C80, take ε cu =0.003; the intermediate strength level is obtained by linear interpolation; h—total height of the steel-concrete composite bridge; ε a,0 —When considering the influence of secondary force, the hysteresis strain of the reinforced steel plate is calculate; E a —Elastic modulus of the reinforcement steel plate; M k —Standard value of bending moment acting on the cross section of the steel-concrete composite bridge before reinforcement; y1—the distance between the resultant force of the cross-sectional stress of the steel beam before reinforcement and the resultant force of the cross-sectional stress of the concrete compression zone; y2—The distance between the resultant force of the reinforced steel plate and the resultant force of the cross-sectional stress in the compression zone of the concrete.

4. The reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure according to claim 2 is characterized in that: In S100, in the positive moment action section, when the plastic neutral axis is inside the steel beam, the steel beam close to the concrete slab is under compression, and the steel beam away from the concrete slab is under tension, and the steel compressive and tensile strengths are evenly reached. The compressive bearing capacity of the positive section of the reinforced bridge should meet the requirements of (2-1) and (2-2): γ0M d ≤b eff h c f cd y5+Aη a f ad y4+A c0 f ad0 y3 (2-1) Where: M d —Design value of bending moment after bridge reinforcement; b eff —Effective width of concrete slab; h c —Total thickness of concrete slab; f cd —Design value of compressive strength of concrete slab; A—cross-sectional area of ​​reinforced steel plate; η a —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1; f ad —Design value of strength of reinforced steel plate; A c0 —Cross-sectional area of ​​the steel beam under compression; f ad0 —Design value of steel beam strength before reinforcement; y3—the distance from the centroid of the cross section of the steel beam in tension to the centroid of the cross section of the steel beam in compression; y4—the distance from the centroid of the steel beam section in the tension zone to the centroid of the reinforced steel plate section; y5—The distance from the centroid of the steel beam section in the tension zone to the centroid of the concrete slab section.

5. The reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure according to claim 2 is characterized in that: In S100, in the negative moment action section, the compressive bearing capacity of the positive section of the reinforced bridge shall comply with the provisions of (3-1), (3-2), (3-3), and (3-4): γ0M d ≤A cf η cf f cf y9+A s f sd y8+Aη a f ad y7+(A0-A c0 )f ad0 y6 (3-1) Where: A cf —Cross-sectional area of ​​carbon fiber composite; f cf —Design value of tensile strength of carbon fiber composites; M d —Design value of bending moment after bridge reinforcement; η cf —When considering the influence of secondary force, the reduction factor of the tensile strength of carbon fiber composite material cannot reach the calculated value, η cf ≤1; A s —The cross-sectional area of ​​longitudinal reinforcement within the effective width of the concrete slab in the negative bending moment zone; f sd —Design value of longitudinal reinforcement tensile strength; A—cross-sectional area of ​​reinforced steel plate; η a —When considering the influence of secondary force, the reduction factor of the tensile strength of the reinforced steel plate in the tension zone cannot reach the calculated value, η a ≤1; f ad —Design value of strength of reinforced steel plate; A c0 —Cross-sectional area of ​​the steel beam under compression; f ad0 —Design value of steel beam strength before reinforcement; x2—the distance from the neutral axis of the cracked section to the top of the beam; h—total height of the steel-concrete composite bridge; ε cf —The tensile strain design value of carbon fiber composite is 0.007; ε cf,0 —The hysteresis strain of carbon fiber composites when considering the influence of secondary forces; E s —elastic modulus of longitudinal reinforcement; E a —Elastic modulus of the reinforcement steel plate; M k —Standard value of bending moment acting on the cross section of the steel-concrete composite bridge before reinforcement; h0—effective compression height of the section; y6—the distance from the centroid of the cross section of the steel beam in compression to the centroid of the cross section of the steel beam in tension; y7—the distance from the centroid of the cross section of the steel beam in the compression zone to the centroid of the cross section of the reinforced steel plate; y8—the distance from the centroid of the steel beam compression zone section to the centroid of the longitudinal reinforcement section; y9—The distance from the centroid of the steel beam cross section in the compression zone to the top of the steel-concrete composite beam.

6. The reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure according to claim 2 is characterized in that: In S200, the maximum crack width W of the concrete in the negative moment section under the normal service limit state cr It shall comply with the provisions of (4-1), (4-2) and (4-3): Where: W cr —The maximum crack width of the concrete in the negative moment section under the serviceability limit state; E cf —Elastic modulus of carbon fiber composites; C1—Steel surface shape coefficient, for smooth steel bars, C1=1.40; for ribbed steel bars, C1=1.00; for epoxy resin coated ribbed steel bars, C1=1.15; C2—Long-term effect coefficient, M l and M s are the design values ​​of bending moments (or axial forces) calculated for the quasi-permanent combination and the frequently occurring combination respectively; C3—coefficient related to the stress properties of the member. For continuous bridges with steel-concrete composite structures, C3=1.0; c—thickness of the concrete cover of the outermost row of longitudinal tensile reinforcements in the concrete bridge deck. When c>50mm, take 50mm; d—diameter of longitudinal tensile reinforcement; σ s —Equivalent stress of steel bars; E s —elastic modulus of longitudinal reinforcement; ρ te —Equivalent reinforcement ratio of longitudinal reinforcement, 0.01≤ρ te ≤0.1; A s —The cross-sectional area of ​​longitudinal reinforcement within the effective width of the concrete slab in the negative bending moment zone; M d —Design value of bending moment after bridge reinforcement; f ad0 —Design value of steel beam strength before reinforcement; W np0 —Plastic section moment of inertia of the steel beam section before reinforcement; f ad —Design value of strength of reinforced steel plate; W np —Moment of inertia of the plastic section of the reinforced steel plate; y 10 —The distance from the centroid of the longitudinal reinforcement section to the plastic neutral axis of the steel-concrete composite structural beam; y 11 —The distance from the plastic neutral axis of a pure steel beam to the plastic neutral axis of a steel-concrete composite structural beam.

7. The reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure according to any one of claims 1 to 6, characterized in that: In S10, the inspection items include appearance inspection, non-destructive testing and load testing. The inspection and evaluation results of the bridge include the damage condition, bearing capacity and actual stress performance of the bridge.

8. The reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure according to any one of claims 1 to 6, characterized in that: In S20, the bridge reinforcement plan includes the selection of reinforcement methods, the determination of reinforcement materials, the formulation of construction techniques and the design of reinforcement structures, and the design of reinforcement structures includes the design of anchor length and spacing.

9. The reinforcement design method applicable to a continuous bridge of a steel-concrete composite structure according to any one of claims 1 to 6, characterized in that: In S30, when modeling, actual test parameters are input to recalculate the bearing capacity of the bridge under the existing disease condition; when judging the structural safety reserve, a safety value is selected based on the original design standard of the bridge and / or the current bridge design specification.

10. A continuous bridge with a steel-concrete composite structure, characterized in that: Reinforcement based on the reinforcement design method applicable to continuous bridges of steel-concrete composite structures described in any one of claims 1-9.

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