Steel-concrete combined orthotropic bridge deck slab and design method thereof

Abstract

The invention discloses a steel-concrete combined orthotropic bridge deck slab and a design method thereof, relates to the technical field of civil engineering, and solves the technical problems of large dead weight and high steel content of a bridge deck slab in the prior art. The structure comprises a concrete layer, a reinforcing mesh and a bottom steel plate are arranged in the concrete layer, the bottom steel plate is arranged at the bottom of the concrete layer, perforated steel plates are vertically arranged between the reinforcing mesh and the bottom steel plate, the perforated steel plates are arranged in an array mode, and trapezoidal hollows are formed in the concrete layer between the perforated steel plates which are longitudinally arranged. The reinforcing mesh comprises transverse reinforcing steel bars and longitudinal reinforcing steel bars, when the concrete layer is poured, concrete flows into round holes of the perforated steel plate to form a concrete tenon shear connector, and the concrete layer is made of ultra-high-performance concrete; the concrete is high in hollowing rate, small in cross section area and light in self weight, and the problem that a steel-concrete orthotropic bridge deck slab is large in self weight is solved.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a steel-concrete composite orthotropic bridge deck and a design method thereof. Background Art

[0002] The steel-concrete composite orthotropic slab is a bridge deck that has developed rapidly in recent years. The steel-concrete composite orthotropic slab is a bridge deck that has cast an ordinary concrete layer or an ultra-high performance concrete layer on the steel orthotropic bridge deck. It can significantly improve the stiffness of the steel orthotropic bridge deck and greatly alleviate the fatigue problem of the steel orthotropic bridge deck. However, its concrete layer is mostly in the form of a solid slab, which increases the deadweight of the structure and the first-phase constant load stress of the steel structure. At the same time, due to the high steel content and large amount of steel used, its economic efficiency is greatly reduced, and its scope of application is mainly limited to extra-large span bridges with strict restrictions on the deadweight of the bridge deck. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present invention provides a steel-concrete composite orthotropic bridge deck and a design method thereof, which solves the technical problems of heavy self-weight and high steel content of the bridge deck in the prior art.

[0004] A steel-concrete composite orthotropic bridge deck comprises a concrete layer, wherein a steel mesh and a bottom steel plate are arranged in the concrete layer, wherein the bottom steel plate is arranged at the bottom of the concrete layer, wherein the steel mesh is arranged above the bottom steel plate, and a perforated steel plate is vertically arranged between the steel mesh and the bottom steel plate, wherein the perforated steel plates are arranged in an array, and the concrete layer between the longitudinally arranged perforated steel plates is provided with a trapezoidal hollowing, wherein the steel mesh comprises transverse steel bars and longitudinal steel bars, and when the concrete layer is poured, the concrete flows into the circular holes of the perforated steel plates to form concrete tenon shear connectors, and wherein the concrete layer adopts ultra-high performance concrete.

[0005] Specifically, the concrete and the bottom steel plate are connected longitudinally to form a steel-concrete composite plate; the steel mesh is supported on the top of the perforated steel plate, the longitudinal steel bars are arranged on the upper layer, and the transverse steel bars are arranged on the lower layer, forming a reinforced concrete plate reinforced by the transverse steel bars upwards.

[0006] Furthermore, the thickness of the bottom steel plate is 8mm to 10mm, the length S3 of the upper bottom of the trapezoidal hollowing is not greater than 400mm, the length S4 of the lower bottom of the trapezoidal hollowing is not greater than 500mm, the angle between the hypotenuse of the trapezoidal hollowing and the horizontal line is not less than 60°, and the minimum spacing S2 of the trapezoidal hollowing space is not less than 100mm; the diameter of the transverse steel bars of the steel mesh is between 8mm and 12mm, and the diameter of the longitudinal steel bars of the steel mesh is between 16mm and 22mm.

[0007] A design method for a steel-concrete composite orthotropic bridge deck comprises the following steps:

[0008] Step 1: Determine the longitudinal spacing S1 of the perforated steel plates;

[0009] Step 2: Determine the thickness h of the concrete layer and the effective height h1, wherein the effective height h1 refers to the height from the upper bottom edge of the trapezoidal hollowing to the top of the concrete layer;

[0010] Step 3: Calculate the shear strength of the bridge deck;

[0011] Step 4: Calculate the bending bearing capacity M of the bridge deck under the positive bending moment max ;

[0012] Step 5: Calculate the bending bearing capacity Mu of the bridge deck under the negative bending moment (when the bottom steel plate is in the compression zone).

[0013] Specifically, after the calculation is completed, the relevant construction personnel can verify the shear strength, the bending bearing capacity under the positive bending moment M max And whether the flexural bearing capacity Mu under negative bending moment meets the construction requirements.

[0014] Furthermore, the step 1 comprises:

[0015] Step 1.1: Calculate the shear force envelope diagram according to the transverse shear force influence line and obtain the maximum shear force per unit longitudinal length Q max ;

[0016] Step 1.2: Calculate the number of concrete dowel shear connectors n required for a bridge deck with a width of b2 and a length of unit length (per meter)

[0017]

[0018] Where: f c is the cube strength of ultra-high performance concrete, f c ≤140MPa, A cj is the concrete tenon area;

[0019] Step 1.3: Determine the hole spacing S5 of the perforated steel plate according to the "Design and Construction Specifications for Highway Steel-Concrete Composite Bridges";

[0020] Step 1.4: Calculate the spacing S1 of the perforated steel plates

[0021]

[0022] Where n2 is the number of concrete tenon shear connectors per unit length of the bridge deck.

[0023] Furthermore, the step 2 comprises:

[0024] Step 2.1: Calculate the bending moment M borne by the cross section of a single bridge deck unit;

[0025] Step 2.2: Calculate the height ξ of the compression zone at the cross-section boundary b ;

[0026]

[0027] Where: β is the conversion factor of the cross-section compression zone height, f s is the design strength of the bottom steel plate material, E s is the elastic modulus of the bottom steel plate, ε cu is the ultimate compressive strain of concrete, which is taken as 0.0027;

[0028] Step 2.3: Calculate the theoretical height of the cross section based on the cross section bending moment balance

[0029]

[0030] Where: A s is the bottom steel plate area of ​​a single bridge deck unit, h c is the theoretical height of the cross section;

[0031] Step 2.4: Calculate the concrete layer thickness h

[0032] h=max(h c ,(b1+d1+d2+c))

[0033] Where: b1 is the height of the perforated steel plate, d1 is the diameter of the bottom steel bar, d2 is the diameter of the top steel bar, and c is the thickness of the protective layer;

[0034] Step 2.5: Calculate the effective height of the concrete layer h1

[0035] h1=ξ b h.

[0037] Further, step 3 includes:

[0038] Step 3.1: Calculate the maximum shear force V borne by a single bridge deck unit using the quasi-orthotropic bridge deck method u ;

[0039] Step 3.2: Calculate the shear force V shared by the steel fibers in the concrete layer of a single bridge deck unit f ;

[0040]

[0041] Where, d f is the steel fiber diameter, ρ f Steel fiber volume ratio, l f is the fiber length, τ f is the average bond strength, γ is the fiber effective action coefficient, λ is the shear span ratio, S2 is the rib width of a single bridge deck unit, that is, the minimum spacing S2 of the trapezoidal excavation space;

[0042] Step 3.3: Calculate the shear contribution V of the concrete in the shear zone of a single bridge deck element c

[0043]

[0044] In the formula, ρ s is the steel content of the cross section, only the bottom steel plate is included;

[0045] Step 3.4: Calculate the shear strength of the bridge deck

[0046] V=V c +V f

[0047] Step 3.5: If V ≥ V u , the shear bearing capacity meets the requirements, if V<V u , increase S2, repeat 3.2 to 3.4 until V ≥ V u .

[0048] Furthermore, the step 5 comprises:

[0049] Determine whether the neutral axis is in the bottom steel plate and then perform the corresponding calculation; if it satisfies formula (8), the neutral axis is in the bottom steel plate; otherwise, the neutral axis is in the concrete.

[0050]

[0051] In the formula, f sb is the design strength of the longitudinal reinforcement, A sb is the longitudinal reinforcement area, is the stress non-uniformity coefficient of ultra-high performance concrete in the tension zone f t is the tensile design strength of ultra-high performance concrete, Ac is the concrete area;

[0052] Furthermore, if the neutral axis is within the bottom steel plate, the calculation process includes:

[0053] Step 5.11: Calculate the neutral axis position

[0054]

[0055] In the formula, b is the full width of the bridge deck, and x is the height of the bottom steel plate compression zone. The neutral axis position x and h are calculated by this formula: s is the thickness of the bottom steel plate;

[0056] Step 5.12: Calculate the bending capacity M u

[0057]

[0058] Furthermore, if the central axis is in the concrete, the calculation process includes:

[0059] Step 5.21: Calculate the neutral axis position

[0060] f s bh s +f c bx c =f sb A sb +f t bh1

[0061] Where b is the full width of the bridge deck, x c is the height of the concrete compression zone; the neutral axis position x is calculated from this formula c ;

[0062] Step 5.22: Calculate the bending capacity M u

[0063]

[0064] Substitute x into the above formula and calculate M u .

[0065] The beneficial effects of the present invention include:

[0066] (1) The concrete hollowing rate is high, the cross-sectional area is small, and the deadweight is light, which solves the problem of heavy deadweight of steel-concrete orthotropic bridge deck.

[0067] (2) The steel plate and concrete are far away from the central axis, with high bending efficiency, large cross-sectional inertia moment and high bending stiffness.

[0068] (3) Compared with steel-concrete composite orthotropic bridge decks, the absence of stiffening ribs greatly reduces the amount of steel used and reduces the cost, thus solving the problem of large steel consumption and high cost of steel-concrete composite orthotropic bridge decks.

[0069] (4) The cross-sectional design method for covering the perforated steel plate, concrete layer thickness, concrete effective thickness, and key parameters such as the bottom steel plate thickness are proposed, solving the problem of the current experience-based design of steel-concrete orthotropic bridge decks.

[0070] (5) The proposed calculation method does not require finite element modeling and is more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is a partial schematic diagram of a steel-concrete composite orthotropic bridge deck.

[0072] Figure 2 Schematic diagram of the calculation of bending bearing capacity when the neutral axis is inside the steel plate.

[0073] Figure 3 Schematic diagram of the calculation of bending capacity when the central axis is in concrete.

[0074] Figure 4 This is a front view of a steel-concrete composite orthotropic bridge deck.

[0075] Figure 5 It is a three-dimensional composite orthotropic bridge deck. Figure 1 .

[0076] Figure 6 It is a three-dimensional composite orthotropic bridge deck. Figure 2 .

[0077] Figure 7 It is a three-dimensional composite orthotropic bridge deck. Figure 3 .

[0078] Reference numerals

[0079] 101-bottom steel plate, 102-trapezoidal hollowing, 103-perforated steel plate, 1031-circular hole, 201-concrete layer, 202-steel mesh, 2021-transverse steel bars, 2022-transverse steel bars. DETAILED DESCRIPTION

[0080] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0081] A steel-concrete composite orthotropic bridge deck, such as Figure 4-7 As shown, it includes a concrete layer 201, in which a steel mesh and a bottom steel plate 101 are provided, the bottom steel plate 101 is arranged at the bottom of the concrete layer 201, the steel mesh is arranged above the bottom steel plate 101, and a perforated steel plate 103 is vertically provided between the steel mesh and the bottom steel plate 101, the perforated steel plates 103 are arranged in an array, and the concrete layer 201 between the longitudinally arranged perforated steel plates 103 is provided with a trapezoidal hollowing 102, the steel mesh includes transverse steel bars 2021 and longitudinal steel bars, and when the concrete layer 201 is poured, the concrete flows into the circular holes 1031 of the perforated steel plates 103 to form a concrete tenon shear connector.

[0082] Specifically, the trapezoidal hollowing 102 is a trapezoidal through hole arranged longitudinally, and the concrete and the bottom steel plate 101 are connected longitudinally to form a steel-concrete composite plate; the steel mesh is supported on the top of the perforated steel plate 103, the longitudinal steel bars are arranged in the upper layer, and the transverse steel bars 2021 are arranged in the lower layer, forming a reinforced concrete slab reinforced by the transverse steel bars 2021 upwards.

[0083] Furthermore, the thickness of the bottom steel plate 101 is 8mm to 10mm, the length S3 of the upper bottom of the trapezoidal hollowing out 102 is not greater than 400mm, the length S4 of the lower bottom of the trapezoidal hollowing out 102 is not greater than 500mm, the angle between the hypotenuse of the trapezoidal hollowing out 102 and the horizontal line is not less than 60o, and the minimum spacing S2 between the trapezoidal hollowing out 102 is not less than 100mm; the diameter of the transverse steel bars 2021 of the steel mesh is between 8mm and 12mm, and the diameter of the longitudinal steel bars of the steel mesh is between 16mm and 22mm.

[0084] In another embodiment, a method for designing a steel-concrete composite orthotropic bridge deck is provided, which is used to design a steel-concrete composite orthotropic bridge deck, such as Figure 1-3 As shown, the following steps are included:

[0085] Step 1: Determine the longitudinal spacing S1 of the perforated steel plates;

[0086] Step 2: Determine the thickness h and effective height h1 of the concrete layer, where the effective height h1 refers to the height from the upper bottom edge of the trapezoidal hollowing to the top of the concrete layer; the upper bottom edge of the trapezoidal hollowing refers to the edge of the top plane of the trapezoid;

[0087] Step 3: Calculate the shear strength of the bridge deck;

[0088] Step 4: Calculate the bending bearing capacity M of the bridge deck under positive bending moment max , specifically calculated in accordance with the "Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts";

[0089] Step 5: Calculate the bending bearing capacity Mu of the bridge deck under the action of negative bending moment (when the bottom steel plate is in the compression zone).

[0090] In another embodiment, the step 1 comprises:

[0091] Step 1.1: Calculate the shear force envelope diagram according to the transverse shear force influence line and obtain the maximum shear force per unit longitudinal length Q max ;

[0092] Step 1.2: Calculate the number of concrete dowel shear connectors n required for a bridge deck with a width of b2 and a length of unit length (per meter)

[0093]

[0094] Where: f cis the cube strength of ultra-high performance concrete, f c ≤140MPa, Acj is the concrete tenon area;

[0095] Step 1.3: Determine the hole spacing S5 of the perforated steel plate according to the "Design and Construction Specifications for Highway Steel-Concrete Composite Bridges";

[0096] Step 1.4: Calculate the spacing S1 between the opening steel plates:

[0097]

[0098] Where b1 is the full width of the bridge deck and n2 is the number of concrete tenon shear connectors per unit length of the bridge deck.

[0099] In another embodiment, the step 2 comprises:

[0100] Step 2: Determine the thickness h and effective height h1 of the concrete layer;

[0101] Step 2.1: Calculate the bending moment M borne by a single bridge deck unit;

[0102] Step 2.2: Calculate the height ξ of the compression zone at the cross section of the bridge deck unit b

[0103]

[0104] Where: β is the conversion factor of the cross-section compression zone height, f s is the design strength of the bottom steel plate material, E s is the elastic modulus of the bottom steel plate, ε cu is the ultimate compressive strain of concrete, which is taken as 0.0027.

[0105] Step 2.3: Calculate the theoretical height of the cross section based on the cross section bending moment equilibrium

[0106]

[0107] Where: A s is the bottom steel plate area of ​​a single bridge deck unit, h c is the theoretical height of the cross section;

[0108] Step 2.4: Calculate the concrete layer thickness h

[0109] h=max(h c ,(b1+d1+d2+c))

[0110] Where: b1 is the height of the perforated steel plate, d1 is the diameter of the bottom steel bar, d2 is the diameter of the top steel bar, and c is the thickness of the protective layer;

[0111] Step 2.5: Calculate the effective height of the concrete layer h1

[0112] h1=ξ b h

[0113] In another embodiment, the step 3 comprises:

[0114] Step 3.1: Calculate the maximum shear force V borne by a single bridge deck unit using the quasi-orthotropic bridge deck method u ;

[0115] Step 3.2: Calculate the shear force V shared by the steel fibers in the concrete layer of a single bridge deck unit f ;

[0116]

[0117] Where, d f is the steel fiber diameter, ρ f Steel fiber volume ratio, l f is the fiber length, τ f is the average bond strength, γ is the fiber effective action coefficient, γ = 0.763, λ is the shear span ratio, S2 is the rib width of a single bridge deck unit, that is, the minimum spacing S2 of the trapezoidal excavation space;

[0118] Step 3.3: Calculate the shear contribution V of the concrete in the shear zone of a single bridge deck element c

[0119]

[0120] In the formula, ρ s is the steel content of the cross section, only the bottom steel plate is included;

[0121] Step 3.4: Calculate the shear strength of the bridge deck

[0122] V=V c +V f

[0123] Step 3.5: If V ≥ V u , the shear bearing capacity meets the requirements, if V<V u , increase S2, repeat 3.2 to 3.4 until V ≥ V u .

[0124] In another embodiment, step 5 comprises:

[0125] Determine whether the neutral axis is in the bottom steel plate. If the following equation is satisfied, the neutral axis is in the bottom steel plate, otherwise the neutral axis is in the concrete;

[0126]

[0127] In the formula, f sb is the design strength of the longitudinal reinforcement, A sb is the longitudinal reinforcement area, is the stress non-uniformity coefficient of ultra-high performance concrete in the tension zone f t A is the tensile design strength of ultra-high performance concrete, c is the concrete area;

[0128] If the neutral axis is inside the bottom steel plate, Figure 2 As shown, the calculation process includes:

[0129] Step 5.11: Calculate the neutral axis position

[0130]

[0131] In the formula, b is the full width of the bridge deck, and x is the height of the bottom steel plate compression zone; the neutral axis position x, h is calculated from this formula: s is the thickness of the bottom steel plate;

[0132] Step 5.12: Calculate the bending capacity M u

[0133]

[0134] If the central axis is in concrete, Figure 3 As shown, the calculation process includes:

[0135] Step 5.21: Calculate the neutral axis position

[0136] f s bh s +f c bx c =f sb A sb +f t bh1

[0137] Where b is the full width of the bridge deck, x c is the height of the concrete compression zone; the neutral axis position x is calculated from this formula c .

[0138] Step 5.22: Calculate the bending capacity M u

[0139]

[0140] Substitute x into the above formula and calculate M u .

[0141] Specifically, after the above calculations are completed, the relevant construction personnel can verify the shear strength, the bending bearing capacity under the positive bending moment M max And whether the flexural bearing capacity Mu under negative bending moment meets the construction requirements.

[0142] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A steel-concrete composite orthotropic bridge deck, characterized in that: The invention comprises a concrete layer (201), wherein a steel mesh and a bottom steel plate (101) are arranged in the concrete layer (201), wherein the bottom steel plate (101) is arranged at the bottom of the concrete layer (201), wherein the steel mesh is arranged above the bottom steel plate (101), and wherein a perforated steel plate (103) is vertically arranged between the steel mesh and the bottom steel plate (101), wherein the perforated steel plates (103) are arranged in an array, and wherein the concrete layer (201) between the perforated steel plates (103) arranged in the longitudinal direction is provided with a trapezoidal hollowing (102), wherein when the concrete layer (201) is poured, the concrete flows into the circular hole (1031) of the perforated steel plate (103) to form a concrete tenon shear connector, and wherein the concrete layer (201) adopts ultra-high performance concrete.

2. The preferred steel-concrete composite orthotropic bridge deck according to claim 1 is characterized in that: The thickness of the bottom steel plate (101) is 8 mm to 10 mm, the length S3 of the upper bottom of the trapezoidal hollowing (102) is not greater than 400 mm, the length S4 of the lower bottom of the trapezoidal hollowing (102) is not greater than 500 mm, the angle between the hypotenuse of the trapezoidal hollowing (102) and the horizontal line is not less than 60 degrees, and the minimum spacing S2 between the trapezoidal hollowings (102) is not less than 100 mm; the diameter of the transverse steel bars (2021) of the steel mesh is between 8 mm and 12 mm, and the diameter of the longitudinal steel bars of the steel mesh is between 16 mm and 22 mm.

3. A design method for a steel-concrete composite orthotropic bridge deck, characterized in that: The method for designing a steel-concrete composite orthotropic bridge deck as claimed in any one of claims 1 to 2 comprises the following steps: Step 1: Determine the longitudinal spacing S1 of the perforated steel plates; Step 2: Determine the thickness h and effective height h1 of the concrete layer; the effective height refers to the height from the upper bottom edge of the trapezoidal hollowing to the top of the concrete layer; Step 3: Calculate the shear strength of the bridge deck; Step 4: Calculate the bending bearing capacity M of the bridge deck under the positive bending moment max ; Step 5: Calculate the bending bearing capacity M of the bridge deck under negative bending moment u .

4. The design method of a steel-concrete composite orthotropic bridge deck according to claim 3 is characterized in that: The step 1 comprises: Step 1.1: Calculate the shear force envelope diagram according to the transverse shear force influence line and obtain the maximum shear force per unit longitudinal length Q max ; Step 1.2: Calculate the number of concrete dowel shear connectors n required for a bridge deck with width b2 and unit length Where: f c is the cube strength of ultra-high performance concrete, f c ≤140MPa, A cj is the concrete tenon area; Step 1.3: Determine the hole spacing S5 of the perforated steel plate according to the design specifications; Step 1.4: Calculate the spacing S1 of the holes in the perforated steel plate Where n2 is the number of concrete tenon shear connectors per unit length of the bridge deck.

5. The design method of a steel-concrete composite orthotropic bridge deck according to claim 3 is characterized in that: The step 2 comprises: Step 2.1: Calculate the bending moment M borne by a single bridge deck unit; the bridge deck unit refers to the bridge deck between the midpoints of two adjacent trapezoidal hollows; Step 2.2: Calculate the height ξ of the compression zone of the cross section of a single bridge deck unit b ; Where: β is the conversion factor of the cross-section compression zone height, f s is the design strength of the bottom steel plate material, E s is the elastic modulus of the bottom steel plate, ε cu is the ultimate compressive strain of concrete; Step 2.3: Calculate the theoretical height of the cross section based on the moment balance of the cross section of a single bridge deck unit; Where: A s is the bottom steel plate area of ​​a single calculated bridge deck unit, h c is the theoretical height of the cross section; Step 2.4: Calculate the concrete layer thickness h h=max(h c ,(b1+d1+d2+c)) Where: b1 is the height of the perforated steel plate, d1 is the diameter of the bottom steel bar, d2 is the diameter of the top steel bar, and c is the thickness of the protective layer; Step 2.5: Calculate the effective height of the concrete layer h1 h1=ξ b h。 6. The design method of a steel-concrete composite orthotropic bridge deck according to claim 4 is characterized in that: The step 3 comprises: Step 3.1: Calculate the maximum shear force V borne by a single bridge deck unit using the quasi-orthotropic bridge deck method u ; Step 3.2: Calculate the shear force V shared by the steel fibers in the concrete layer of a single bridge deck unit f ; Where, d f is the steel fiber diameter, ρ f Steel fiber volume ratio, l f is the fiber length, τ f is the average bond strength, γ is the fiber effective action coefficient, λ is the shear span ratio, S2 is the rib width of a single bridge deck unit, that is, the minimum spacing S2 of the trapezoidal excavation space; Step 3.3: Calculate the shear contribution V of the concrete in the shear zone of a single bridge deck element c In the formula, ρ s is the steel content of the cross section, only the bottom steel plate is included; Step 3.4: Calculate the shear strength of the bridge deck V=V c +V f Step 3.5: If V ≥ V u , the shear bearing capacity meets the requirements, if V<V u , increase S2, repeat 3.2 to 3.4 until V ≥ V u .

7. The design method of a steel-concrete composite orthotropic bridge deck according to claim 4 is characterized in that: The step 5 comprises: Determine whether the neutral axis is within the bottom steel plate and then perform corresponding calculations; If the following equation is satisfied, the neutral axis is in the bottom steel plate, otherwise the neutral axis is in the concrete; In the formula, f sb is the design strength of the longitudinal reinforcement, A sb is the area of ​​longitudinal reinforcement, is the stress non-uniformity coefficient of ultra-high performance concrete in the tension zone, f t A is the tensile design strength of ultra-high performance concrete. c is the concrete area, f s A is the design strength of the bottom steel plate material, s is the bottom steel plate area of ​​a single calculated plate unit.

8. The design method of a steel-concrete composite orthotropic bridge deck according to claim 7 is characterized in that: If the neutral axis is in the bottom plate, the calculation process includes: Step 5.11: Calculate the neutral axis position x Where b is the full width of the bridge deck, x is the height of the bottom steel plate under compression, and h is s is the thickness of the bottom steel plate; Step 5.12: Calculate the bending capacity M u 9. The design method of a steel-concrete composite orthotropic bridge deck according to claim 7 is characterized in that: If the central axis is in the concrete, the calculation process includes: Step 5.21: Calculate the neutral axis position f s bh s +f c bx c =f sb A sb +f t bh1 Where b is the full width of the bridge deck, x c is the height of the concrete compression zone; the neutral axis position x is calculated from this formula c， ; Step 5.22: Calculate the bending capacity M u Substitute x into the above formula and calculate M u .

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