A method for calculating key parameters of a pre-assembled steel structure complete combined beam

Abstract

This invention discloses a method for calculating key parameters of pre-assembled steel structure composite beams, comprising the following steps: 1) data acquisition; 2) model simplification; 3) material property setting; 4) mesh generation; 5) load combination and simulation analysis; 6) correction verification: substituting the pre-assembly characteristic parameters from step 5) into the verification formula, performing correction verifications on web shear strength, composite beam stiffness, splice joint bearing capacity, and bridge deck cracks respectively. If all verifications meet the corresponding qualification criteria, the key parameters of the pre-assembled steel structure composite beam are deemed to meet the design requirements. This invention establishes a complete calculation system of "pre-assembly characteristic parameters - finite element model - dedicated verification standards" by setting calculation methods for three exclusive parameters: splice joint stiffness reduction coefficient ζ, splice joint local stress correction coefficient η, and splice joint interface bonding coefficient k, thereby achieving accurate prediction of key parameters of pre-assembled composite beams.

Description

Technical Field

[0001] This invention relates to the field of calculating key parameters of composite beams, and specifically to a method for calculating key parameters of pre-assembled steel structure composite beams. Background Technology

[0002] Currently, my country is in a stage of rapid development in the construction of urban transportation and intercity high-speed railways. Some existing structural forms are no longer able to meet the higher requirements of new projects in terms of structural bearing capacity, stiffness and durability.

[0003] Precast steel-concrete composite beams offer advantages such as high overall and local stiffness, low steel consumption, transparent structure, and convenient construction, leading to their increasingly widespread application. Currently, there are no theoretical calculation methods for the stiffness and ultimate bearing capacity of steel-concrete composite beams; calculations can only be approximated as for solid-web composite beams. If calculated as a solid-web composite beam, its section shear force and ultimate bearing capacity cannot be calculated.

[0004] Therefore, it is necessary to design a set of calculation methods for key parameters of pre-assembled steel structure composite beams to solve the above-mentioned technical problems. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to propose a method for calculating key parameters of pre-assembled steel structure composite beams.

[0006] Based on the above objectives, the present invention adopts the following technical solution: A method for calculating key parameters of pre-assembled steel structure composite beams includes the following steps: 1) Data Acquisition: Basic data acquisition and pre-assembly feature data acquisition; 2) Model simplification: The pre-assembled steel composite beam structure diagram is simplified into a three-dimensional finite element model, which includes a concrete bridge deck model, a steel main beam model, assembly joint contact elements, and splicing node solid models. 3) Material property settings: Set the mechanical parameters of the base material and the parameters of the pre-assembled characteristic materials; 4) Grid generation; 5) Load combination and simulation analysis: a) Apply load combinations, which include conventional loads and assembly construction loads; b) Apply boundary conditions: Set contact constraints at the assembly joints, and apply constraints to the splicing nodes according to the actual stress state; c) Calculate key parameter data: Calculate conventional mechanical response parameter data and pre-assembly characteristic parameter data, wherein the pre-assembly characteristic parameters include the stiffness reduction factor ζ of the assembly joint, the local stress correction factor η of the splicing node, and the bonding coefficient k of the assembly joint interface. 6) Correction verification: Substitute the pre-assembly characteristic parameters from step 5) into the verification formula, and perform correction verifications on the web shear strength, composite beam stiffness, splice joint bearing capacity, and bridge deck cracks respectively. If all verifications meet the corresponding qualification criteria, the key parameters of the pre-assembled steel structure complete composite beam are deemed to meet the design requirements.

[0007] In step 1), the basic data includes geometric dimensions, material strength, and load conditions; the pre-assembly feature data includes assembly type, assembly joint structure, and splicing node form. The assembly type includes welded assembly, bolted assembly, and a combination of welded and bolted assembly. In step 5), step c), the stiffness reduction factor ζ of the assembly joint is calculated according to the following formula: ζ = 1 - α•ΔK / K beam , where K beam For the bending stiffness of a complete beam segment without assembly joints, K j The stiffness loss caused by the assembly joint; α is the experimental correction factor; According to the assembly type, K j Calculate using the following formulas respectively: Welding and assembly: ΔK w = K beam •C w C w The weld stiffness loss coefficient is 0.02≤C. w ≤0.05; Bolt assembly: ΔK b =K beam ·C b Among them, C b C is the bolt joint stiffness loss coefficient, 0.05≤C b ≤0.12; Mixed assembly: ΔK=ΔK w +ΔK b .

[0008] In step 5), step c), the local stress correction factor η at the splicing node is calculated according to the following formula: η = 1 + 0.2 • |t j - t f | / max(t j , t f )+0.15• |n b - n b0 | / n b0 , Where: t j t represents the thickness of the splicing panel (mm). f n represents the flange thickness of the main steel beam (mm). b n represents the actual number of bolts. b0The number of bolts is calculated according to the assumption of uniform stress on group bolts in the current "Steel Structure Design Standard" GB 50017.

[0009] In step 5), step c), the bonding coefficient k at the assembly joint interface is calculated according to the following formula: k = 0.85 + 0.03•f y / f y0 +0.02•τ j / τ j0 +0.01•β, Where: f y f is the yield strength of steel (MPa). y0 =345 MPa, τ j τ represents the shear strength (MPa) of the assembly joint interface. j0 =100 MPa, β is the assembly seam working condition adaptation coefficient, 0.2≤β≤1.

[0010] In step 5), step c), the stiffness reduction factor ζ of the assembly joint is: 0.80 ≤ ζ ≤ 0.98; The local stress correction factor η at the splicing node is: 1.05 ≤ η ≤ 1.30; The bonding coefficient k at the assembly joint interface is: 0.85≤k≤0.99; When welding and assembling, β=0.8~1.0; when bolting and assembling, β=0.3~0.7; when mixed assembly, β=0.5~0.9.

[0011] In step 6), a) the web shear strength verification must simultaneously satisfy the following two formulas: γ0•V d ≤V vu •ζ √(σ²+3τ²)≤1.1• f vd •η Where ζ is the stiffness reduction factor of the splice joint, η is the local stress correction factor of the splice node, γ0 is the structural importance coefficient, γ0=1.1, V d V is the design value of web shear force (N) calculated according to the basic combination of ultimate limit state; vu The shear capacity of the web is calculated according to the "Standard for Design of Steel Structures" GB 50017; f vd Let σ and τ be the design value of the web shear strength (MPa), and let σ and τ be the normal stress (MPa) and shear stress (MPa) at the same calculation point on the edge of the web joint of the steel beam under the basic combination of ultimate limit state of bearing capacity, respectively, extracted from the analysis results of step 5). If both of the above formulas are true, then the web shear strength meets the requirements. b) The shear capacity verification of bolts at splice joints shall satisfy the following formula: γ0•V sud ≤V su •ζ Among them, V sud Design shear force of bolt group (N); V su The corrected shear capacity (N) of the bolts at the splice joint is calculated using the following formula: V su =min(V su1 V su2 ); V su1 =0.43•A s •√(E c •f cd ), V su2 =0.7•A s •f su , A s =π•d 2 / 4, Among them, V su1 V su2 Shear capacity (N) of a single shear key; A s The cross-sectional area of ​​a single bolt (mm²); Ec is the elastic modulus of concrete (MPa); f cd f is the design value of the axial compressive strength of concrete (MPa); su denoted as the design value of bolt tensile strength (MPa), taken according to the "Standard for Design of Steel Structures" GB 50017; d is the bolt diameter (mm); ζ is the stiffness reduction factor of the splice joint; if the above inequality holds, then the shear bearing capacity of the bolts at the splice joint meets the requirements; c) The stiffness check of composite beams should satisfy the following formula: B'≥B req Among them, B req B' is the minimum required bending stiffness (N•mm²) calculated according to current bridge design specifications, and B' is the modified bending stiffness of the composite beam (N•mm²), calculated using the following formula: B' = B0 × ζ × k, Where: B0 is the theoretical bending stiffness (N•mm²) of the complete composite beam (without splicing joints and fully shear-resistant connection); k is the bonding coefficient of the splicing joint interface; ζ is the stiffness reduction coefficient of the splicing joint.

[0012] In step 4), the regular area is divided into free tetrahedral meshes; the assembly seam and splicing node area is divided into a dense mesh, and the splicing node mesh growth rate is ≤1.2.

[0013] In step 5), step b), the contact constraints include normal constraints and tangential friction constraints; in step 5), step c), for welding assembly, the test correction factor α = 0.95; for bolt assembly, the test correction factor α = 0.90; for mixed assembly, the test correction factor α = 0.93.

[0014] In this application, the stiffness loss coefficient C of the welded assembly joint is... w This refers to the proportional reduction in the flexural stiffness of the composite beam section compared to the complete beam segment due to factors such as welding residual stress, local weld defects, and section discontinuities caused by the use of full-penetration or semi-penetration welding processes. Welded assembly provides a rigid connection, and the weld can approximately guarantee section continuity, resulting in minimal overall stiffness loss. Full-penetration welds experience uniform stress, with only slight stiffness reduction due to welding residual stress, local penetration differences, and weakened material properties in the heat-affected zone. Based on extensive finite element calculations and actual bridge assembly test data, the stiffness loss caused by welding assembly accounts for approximately 2% to 5% of the stiffness of the complete beam. To cover conditions such as weld quality fluctuations, plate thickness deviations, and differences in construction processes, C... w The range of values ​​is defined as 0.02 ≤ C. w ≤0.05.

[0015] Bolted joint stiffness loss coefficient C b Friction-type joints, formed by high-strength bolts, result in a reduction in the bending stiffness of the composite beam section compared to the intact beam segment due to factors such as bolt slippage, plate gaps, contact surface fit, and local deformation of the joint surface. Bolted connections are semi-rigid connections, with slippery contact surfaces at the joint, making their stiffness weaker than welding. During stress, the joint may experience micro-slippage of the contact surface, bearing pressure on the bolt hole walls, and local bending of the joint plate, all of which further reduce the overall bending stiffness of the section. The stiffness loss is significantly greater than that of welding due to variations in the number of bolts, preload, friction coefficient, and flatness of the joint plate. Based on finite element parametric analysis and full-scale assembly tests, the stiffness loss caused by bolt assembly is approximately 5%–12%. To cover working conditions such as different bolt arrangements, differences in slippage, and fluctuations in construction accuracy, C is used in this application. b The value range is set to 0.05 ≤ C b ≤0.12.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1) The method for calculating key parameters of composite beams in this invention includes data acquisition, model establishment, material property setting, mesh generation, simulation analysis, parameter calculation, and correction verification, which solves the calculation problem of pre-assembled composite beams; 2) The calculation methods for three exclusive parameters, namely the stiffness reduction factor ζ of the splice joint, the local stress correction factor η of the splice node, and the bonding coefficient k of the splice joint interface, were set up. A complete calculation system of "pre-assembly characteristic parameters - finite element model - exclusive verification standard" was established, which enabled the accurate prediction of key parameters of pre-assembly composite beams. Detailed Implementation

[0017] The present invention will be further described below with reference to specific embodiments. Example

[0018] A method for calculating key parameters of pre-assembled steel structure composite beams includes the following steps: 1) Data Acquisition: Basic data acquisition and pre-assembly feature data acquisition; the basic data includes geometric dimensions (span, beam height, slab thickness), material strength (yield strength of steel fy, compressive strength of concrete fcd, modulus of elasticity Ec), and load conditions (dead load, live load, construction load); the pre-assembly feature data includes assembly type, assembly joint structure, and splicing node form, and the assembly type includes welded assembly, bolted assembly, and a combination of welded and bolted assembly; Assembly joint construction: location, length, effective thickness, contact conditions; Joint type: weld size, bolt diameter / quantity / preload / friction coefficient; 2) Model Simplification: The pre-assembled steel composite beam structure diagram is simplified into a three-dimensional finite element model, which includes a concrete bridge deck model (C3D8R solid element), a steel main beam model (S4R shell element or C3D8R solid element), a splicing joint contact element (with contact pairs set, normal "hard contact", and tangential friction coefficient μ taken according to the actual coating or treatment surface (uncoated steel-steel μ=0.3~0.5)), and a splicing node solid model (C3D8I or C3D8R refined solid element). 3) Material property settings: Set the mechanical parameters of the base material and the parameters of the pre-assembled characteristic materials; 4) Mesh generation: Free tetrahedral meshes are used in regular areas, with a size of 50~100mm; denser meshes are used in the splicing seams and splicing nodes, with a splicing node mesh growth rate ≤1.2; 5) Load combination and simulation analysis: a) Apply load combinations, which include conventional loads and assembly construction loads; b) Apply boundary conditions: Set contact constraints at the assembly joint, including normal constraints and tangential friction constraints; apply constraints to the splice node according to the actual stress state (bolt preload, weld continuity); c) Calculate key parameter data: Calculate conventional mechanical response parameter data and pre-assembly characteristic parameter data, wherein the pre-assembly characteristic parameters include the stiffness reduction factor ζ of the assembly joint, the local stress correction factor η of the splicing node, and the bonding coefficient k of the assembly joint interface. In step 5), step c), the stiffness reduction factor ζ of the assembly joint is calculated according to the following formula: ζ = 1 - α•ΔK / K beam , where K beam For the bending stiffness of a complete beam segment without assembly joints, K j The stiffness loss caused by the assembly joint; α is the experimental correction factor; According to the assembly type, K j Calculate using the following formulas respectively: Welding and assembly: ΔK w = K beam •C w C w The weld stiffness loss coefficient is 0.02≤C. w ≤0.05; Bolt assembly: ΔK b =K beam ·C b Among them, C b C is the bolt joint stiffness loss coefficient, 0.05≤C b ≤0.12; Mixed assembly: ΔK=ΔK w +ΔK b .

[0019] The local stress correction factor η at the splicing node is calculated according to the following formula: η = 1 + 0.2 • |t j - t f | / max(t j , t f )+0.15• |n b - n b0 | / n b0 , Where: t j t represents the thickness of the splicing panel (mm). f n represents the flange thickness of the main steel beam (mm). b n represents the actual number of bolts. b0 The number of bolts is calculated according to the assumption of uniform stress of group bolts in the current "Steel Structure Design Standard" GB 50017. The stiffness reduction factor ζ of the assembly joint is: 0.80≤ζ≤0.98; The local stress correction factor η at the splicing node is: 1.05 ≤ η ≤ 1.30; The bonding coefficient k at the assembly joint interface is: 0.85≤k≤0.99; For welding assembly, β = 0.8~1.0; for bolt assembly, β = 0.3~0.7; and for mixed assembly, β = 0.5~0.9. The bonding coefficient k at the joint interface is calculated using the following formula: k = 0.85 + 0.03•f y / f y0 +0.02•τ j / τ j0 +0.01•β, Where: f y f is the yield strength of steel (MPa). y0 =345 MPa, τ j τ represents the shear strength (MPa) of the assembly joint interface. j0 =100 MPa, β is the assembly joint working condition adaptation coefficient, 0.2≤β≤1; 6) Correction verification: Substitute the pre-assembly characteristic parameters from step 5) into the verification formula, and perform correction verifications on the web shear strength, composite beam stiffness, splice joint bearing capacity, and bridge deck cracks respectively. If all verifications meet the corresponding qualification criteria, the key parameters of the pre-assembled steel structure complete composite beam are deemed to meet the design requirements. a) The shear strength verification of the web plate must simultaneously satisfy the following two formulas: γ0•V d ≤V vu •ζ, √(σ²+3τ²)≤1.1• f vd •η Where ζ is the stiffness reduction factor of the splice joint, η is the local stress correction factor of the splice node, γ0 is the structural importance coefficient, γ0=1.1, V d V is the design value of web shear force (N) calculated according to the basic combination of ultimate limit state; vu The shear capacity of the web is calculated according to the "Standard for Design of Steel Structures" GB 50017; f vd Let σ and τ be the design value of the web shear strength (MPa), and let σ and τ be the normal stress (MPa) and shear stress (MPa) at the same calculation point on the edge of the web joint of the steel beam under the basic combination of ultimate limit state of bearing capacity, respectively, extracted from the analysis results of step 5). If both of the above formulas are true, then the web shear strength meets the requirements. b) The shear capacity verification of bolts at splice joints shall satisfy the following formula: γ0•V sud ≤V su •ζ, Where Vsud is the design value of the bolt group shear force (N); V suThe corrected shear capacity (N) of the bolts at the splice joint is calculated using the following formula: V su =min(V su1 V su2 ), V su1 =0.43•A s •√(E c •f cd ), V su2 =0.7•A s •f su , A s =π•d 2 / 4, Among them, V su1 V su2 Shear capacity (N) of a single shear key; A s The cross-sectional area of ​​a single bolt (mm²); Ec is the elastic modulus of concrete (MPa); f cd f is the design value of the axial compressive strength of concrete (MPa); su denoted as the design value of bolt tensile strength (MPa), taken according to the "Standard for Design of Steel Structures" GB 50017; d is the bolt diameter (mm); ζ is the stiffness reduction factor of the splice joint; if the above inequality holds, then the shear bearing capacity of the bolts at the splice joint meets the requirements; c) The stiffness check of composite beams should satisfy the following formula: B'≥B req , Among them, B req The minimum flexural stiffness (N•mm²) calculated according to current bridge design specifications is usually derived from the deflection limit. B' is the modified flexural stiffness (N•mm²) of the composite beam, calculated using the following formula: B' = B0 × ζ × k, Where: B0 is the theoretical bending stiffness (N•mm²) of the complete composite beam (without splicing joints and fully shear-resistant connection), calculated by the equivalent section method; k is the bonding coefficient of the splicing joint interface; ζ is the stiffness reduction factor of the splicing joint.

[0020] Taking a pre-assembled steel-concrete composite beam bridge with a span of 30 m as an example, the key parameters of the composite beam are calculated using the welding assembly method.

[0021] 1) Data collection: Basic data collection: Steel main beam: Q355 steel, yield strength f y =355 MPa, web thickness 12 mm, flange 20×400 mm; Concrete bridge deck: C50 concrete, 200 mm thick, 2000 mm wide, elastic modulus E c =3.45×10 4 MPa, design value of axial compressive strength f cd =23.1 MPa; The span is L=30 m and the beam height is 1.5 m.

[0022] Collect pre-assembled feature data: Assembly type: Full penetration welded assembly, with the assembly seam located 1 / 4 span from the support point; The effective thickness of the weld is 8 mm, and the weld length is 300 mm. 2) Model simplification and mesh generation: A three-dimensional finite element model was built using Abaqus: The concrete bridge deck uses C3D8R solid elements; The main steel beam uses S4R shell elements; Contact pairs are installed at the assembly seams, with normal "hard contact" and tangential friction coefficient μ=0.35; The splicing nodes (weld areas) are modeled using C3D8I solid elements for refinement.

[0023] 3) Basic material mechanical parameters: Steel main beam (Q355 steel): Modulus of elasticity E s =2.06×10 5 MPa, yield strength f y =355 MPa, Poisson's ratio ν s =0.3, density ρ s =7850 kg / m 3 ; Concrete bridge deck (C50 concrete): Modulus of elasticity E c =3.45×10 4 MPa, design value of axial compressive strength f cd =23.1 MPa, Poisson's ratio ν c =0.2, density ρ c =2500 kg / m 3 ; Pre-assembled characteristic material parameters: Weld joint (full penetration): Equivalent elastic modulus E j =1.8×10 5 MPa, Poisson's ratio ν j =0.3; Assembly joint contact: tangential friction coefficient μ=0.35, normal stiffness is taken from the elastic modulus of steel.

[0024] 4) Mesh generation: Free tetrahedral meshes are used in regular areas with a mesh size of 50 mm; dense meshes are used in the splicing seams and splicing nodes, with a splicing node mesh growth rate of 1.15.

[0025] 5) Calculation of pre-assembled characteristic parameters: (1) Stiffness reduction factor ζ of the assembly joint Bending stiffness K of the complete beam segment beam (Calculated based on the mid-span section of a simply supported beam): K beam = E•I = 2.06×10 5 MPa × 2.1 × 10 9 mm 4 = 4.326×10 14 N•mm², C w =0.04, ΔK w = K beam •C w =4.326×10 14 ×0.04 = 1.7304 × 10 13 N•mm², Welding and assembly, taking α=0.95, ζ=1-α•ΔK / K beam =1 - 0.95 × 1.7304 × 10 13 / (4.326×10 14 =0.96.

[0026] (2) Local stress correction factor η at splice joint splicing plate thickness t j =16 mm, steel main beam flange thickness t f =20 mm, actual number of bolts n b =8, the number of bolts under ideal uniform stress n b0 The result calculated according to the standard is 6.

[0027] η = 1 + 0.2×|16-20| / max(16,20) + 0.15×|8-6| / 6 = 1 + 0.04 + 0.05 =1.09.

[0028] (3) Adhesion coefficient k of the assembly joint interface f y =355 MPa, τ j (Average shear strength of the assembly joint interface extracted by finite element method) = 108 MPa, β = 0.9 k= 0.85+0.03×355 / 345+0.02×108 / 100+0.01×0.9=0.85+0.0309 + 0.0216 +0.009= 0.9115; Load combination and finite element calculation: Applying loads: self-weight + secondary dead load + vehicle load (highway-I grade) + assembly construction load (1.2 times self-weight).

[0029] Boundary conditions: Normal binding and tangential friction at the assembly joint (μ=0.35); the supports at both ends are simply supported. Extracted results: Web assembly joint edge: σ=170 MPa, τ=58 MPa; Web shear force design value V d =580 kN; Design value of bolt group shear force V sud =210 kN; Theoretical stiffness of the complete composite beam B0=2.163×10 15 N·mm².

[0030] 5) Correction and verification: Web shear strength verification: V vu (Calculated according to GB50017) = 720 kN, γ0•V d = 1.1 × 580 = 638 kN, V vu •ζ = 720×0.96 = 691.2 kN, →638<691.2; √(σ²+3τ²) = √(170²+3×58²) = √(28900+10092) = √38992 = 197.46MPa, f vd =180 MPa (according to GB 50017, design value of shear strength of Q355 steel). 1.1•f vd •η = 1.1×180×1.09 =215.82MPa, →197.46 MPa < 215.82 MPa The shear strength of the web plate is satisfied.

[0031] Bolt shear capacity verification: A s = π×20² / 4 = 314.2 mm² V su1 =0.43×314.2×√(3.45×10 4×23.1) = 0.43×314.2×√(7.97×10 5 ) =0.43×314.2×892.7 = 120609N≈120.6 kN, V su2 = 0.7 × 314.2 × 400 (Design value of bolt tensile strength) = 87976 N ≈ 88.0 kN, min(V) su1 V su2 = 88.0 kN The design value of the shear force V of the bolt group sud =210 kN (including γ0) is evenly distributed among 8 bolts, and the shear force V of a single bolt is... b =28.9 kN, Corrected shear capacity of a single bolt V su = 88.0 kN, 28.9 kN < 88.0 kN Satisfying γ0•V sud ≤V su •ζ, The calculation passed, and the bolt bearing capacity is satisfied.

[0032] Stiffness check: B' = B0×ζ×k = 2.163×10 15 ×0.96×0.9115 =1.894×10 15 N•mm², B req (Standard limit) = 1.5 × 10 14 N•mm² (calculated from the L / 400 deflection limit) 1.894×10 15 >1.5×10 15 , → B'≥B req The stiffness requirement is met.

[0033] All calculations passed, and the key parameters of the pre-assembled composite beam (ζ=0.96, η=1.09, k=0.9115) were determined to meet the design requirements.

[0034] Taking bolt assembly as an example, M24 high-strength bolts are used for assembly, with a friction coefficient μ=0.35 and a preload F. p =225 kN, elastic modulus E b =2.06×10 5 MPa, tensile strength design value f su =400 MPa, allowable slip s=0.2 mm, number of bolts n b =12, Cb =0.12, α=0.90.

[0035] ΔK = 4.326 × 10 14 × 0.12 = 5.1912×10¹³ N•mm², ζ=1-α•ΔK / K beam =1 - 0.90 × 5.1912 × 10¹³ / (4.326 × 10 14 =0.89.

[0036] η and k are calculated according to Example 1.

[0037] All calculations passed.

[0038] Other verification processes are described in Example 1.

Claims

1. A method for calculating key parameters of pre-assembled steel structure composite beams, characterized in that, Includes the following steps: 1) Data Acquisition: Basic data acquisition and pre-assembly feature data acquisition; 2) Model simplification: The pre-assembled steel composite beam structure diagram is simplified into a three-dimensional finite element model, which includes a concrete bridge deck model, a steel main beam model, assembly joint contact elements, and splicing node solid models. 3) Material property settings: Set the mechanical parameters of the base material and the parameters of the pre-assembled characteristic materials; 4) Grid generation; 5) Load combination and simulation analysis: a) Apply load combinations, which include conventional loads and assembly construction loads; b) Apply boundary conditions: Set contact constraints at the assembly joints, and apply constraints to the splicing nodes according to the actual stress state; c) Calculate key parameter data: Calculate conventional mechanical response parameter data and pre-assembly characteristic parameter data, wherein the pre-assembly characteristic parameters include the stiffness reduction factor ζ of the assembly joint, the local stress correction factor η of the splicing node, and the bonding coefficient k of the assembly joint interface. 6) Correction verification: Substitute the pre-assembly characteristic parameters from step 5) into the verification formula, and perform correction verifications on the web shear strength, composite beam stiffness, splice joint bearing capacity, and bridge deck cracks respectively. If all verifications meet the corresponding qualification criteria, the key parameters of the pre-assembled steel structure complete composite beam are deemed to meet the design requirements.

2. The method for calculating key parameters of pre-assembled steel structure complete composite beams as described in claim 1, characterized in that, In step 1), the basic data includes geometric dimensions, material strength, and load conditions; the pre-assembly feature data includes assembly type, assembly joint structure, and splicing node form. The assembly type includes welded assembly, bolted assembly, and a combination of welded and bolted assembly. In step 5), step c), the stiffness reduction factor ζ of the assembly joint is calculated according to the following formula: ζ = 1 - α•ΔK / K beam , where K beam For the bending stiffness of a complete beam segment without assembly joints, K j The stiffness loss caused by the assembly joint; α is the experimental correction factor; According to the assembly type, K j Calculate using the following formulas respectively: Welding and assembly: ΔK w = K beam •C w C w The weld stiffness loss coefficient is 0.02≤C. w ≤0.05; Bolt assembly: ΔK b =K beam ·C b Among them, C b C is the bolt joint stiffness loss coefficient, 0.05≤C b ≤0.12; Mixed assembly: ΔK=ΔK w +ΔK b .

3. The method for calculating key parameters of pre-assembled steel structure complete composite beams as described in claim 2, characterized in that, In step 5), step c), the local stress correction factor η at the splicing node is calculated according to the following formula: η=1+0.2• |t j - t f | / max(t) j t f )+0.15•|n b - n b0 | / n b0 , Where: t j For the thickness of the splicing panel, t f n is the flange thickness of the steel main beam. b n represents the actual number of bolts. b0 This represents the number of bolts under ideal, uniform stress conditions.

4. The method for calculating key parameters of pre-assembled steel structure complete composite beams as described in claim 3, characterized in that, In step 5), step c), the bonding coefficient k at the assembly joint interface is calculated according to the following formula: k=0.85+0.03•f y / f y0 +0.02•t j / t j0 +0.01•β, Where: f y f is the yield strength of steel. y0 =345 MPa, τ j For the shear strength of the assembly joint interface, τ j0 =100 MPa, β is the assembly seam working condition adaptation coefficient, 0.2≤β≤1.

5. The method for calculating key parameters of pre-assembled steel structure complete composite beams as described in claim 4, characterized in that, In step 5), step c), the stiffness reduction factor ζ of the assembly joint is: 0.80 ≤ ζ ≤ 0.98; The local stress correction factor η at the splicing node is: 1.05 ≤ η ≤ 1.30; The bonding coefficient k at the assembly joint interface is: 0.85≤k≤0.99; When welding and assembling, β=0.8~1.0; when bolting and assembling, β=0.3~0.7; when mixed assembly, β=0.5~0.

9.

6. The method for calculating key parameters of pre-assembled steel structure complete composite beams as described in claim 5, characterized in that, In step 6), a) The shear strength verification of the web plate must simultaneously satisfy the following two formulas: γ0•V d ≤V vu •ζ √(σ²+3τ²)≤1.1• f vd •or Where ζ is the stiffness reduction factor of the splice joint, η is the local stress correction factor of the splice node, γ0 is the structural importance coefficient, γ0=1.1, V d V is the design value of the web shear force. vu f is the shear capacity of the web. vd σ and τ represent the design value of the shear strength of the web plate, respectively, where σ and τ are the normal stress and shear stress at the same calculation point on the edge of the web plate splice joint of the steel beam. b) The shear capacity verification of bolts at splice joints shall satisfy the following formula: γ0•V sud ≤V su •ζ Where Vsud is the design value of the shear force of the bolt group; V… su The shear capacity of the bolts at the corrected splice joint is calculated using the following formula: V su =min(V su1 ,V su2 ); V su1 =0.43•A s •√(E c •f cd ) In su2 =0.7•A s •f su , A s =π•d 2 / 4 Among them, V su1 V su2 The shear capacity of a single shear key; A s E represents the cross-sectional area of ​​a single bolt rod. c f is the elastic modulus of concrete. cd f is the design value of the axial compressive strength of concrete; su d is the design value of bolt tensile strength; d is the bolt diameter; ζ is the stiffness reduction factor of the assembly joint; c) The stiffness check of composite beams should satisfy the following formula: B'≥B req Among them, B req B' is the minimum required bending stiffness calculated according to current bridge design specifications, and B' is the modified bending stiffness of the composite beam, calculated using the following formula: B' = B0 × ζ × k, Where: B0 is the theoretical bending stiffness of the complete composite beam; k is the bonding coefficient of the joint interface; ζ is the stiffness reduction coefficient of the joint.

7. The method for calculating key parameters of pre-assembled steel structure complete composite beams as described in claim 6, characterized in that, In step 4), the regular area is divided into free tetrahedral meshes; the assembly seam and splicing node area is divided into a dense mesh, and the splicing node mesh growth rate is ≤1.

2.

8. The method for calculating key parameters of pre-assembled steel structure complete composite beams as described in claim 7, characterized in that, In step 5), step b), the contact constraints include normal constraints and tangential friction constraints; in step 5), step c), for welding assembly, the test correction factor α = 0.95; for bolt assembly, the test correction factor α = 0.90; for mixed assembly, the test correction factor α = 0.93.