Simplified evaluation, design method and system for double-layer steel truss beam arch combination system

Abstract

The present application relates to the technical field of bridge construction, and in particular to a simplified evaluation, design method and system for a double-layer steel truss girder arch combination system.A simplified evaluation method for a double-layer steel truss girder arch combination system is provided, which can quickly calculate the mid-span deflection δ1 of the steel truss girder and the arch top deflection δ2 in the double-layer steel truss girder arch combination system in combination with a given calculation model, so as to realize rapid evaluation of the bridge design scheme and facilitate preliminary screening of the bridge design scheme.The present application can preliminarily obtain the relationship between the structure parameters and the structure mechanical properties before finite element modeling analysis, which is helpful for designers to understand the mechanical properties of the structure system in the conceptual design stage and to give preliminary and reasonable design parameters.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a simplified evaluation and design method and system for a double-layer steel truss beam-arch composite system. Background Technology

[0002] The double-layer steel truss beam-arch composite system is a highly statically indeterminate structure, generally requiring finite element method (FEM) calculations for completion. However, FEM calculations cannot directly reflect the relationship between structural parameters and structural mechanical properties; structural parameters must be determined based on the designer's experience, or force equations must be established according to the static indeterminacy degree of the structure, which is exceptionally complex to solve using structural mechanics methods. Bridge design needs to consider multiple factors such as materials, dimensions, and structure. Designers provide different design schemes in advance based on experience, and then obtain the performance of each scheme through FEM simulation before selection. FEM simulation is time-consuming, especially for the double-layer steel truss beam-arch composite system due to its structural complexity, where FEM simulation is difficult to meet current efficiency requirements. A faster and more convenient design method is needed. Summary of the Invention

[0003] To overcome the shortcomings of low efficiency in finite element simulation design of bridges in the existing technology, this invention proposes a simplified evaluation method for a double-layer steel truss beam-arch composite system, which can quickly evaluate the performance of different bridge design schemes, thereby facilitating the selection of bridge design schemes.

[0004] This invention proposes a simplified evaluation method for a double-layer steel truss beam-arch composite system, comprising the following steps:

[0005] S1. Obtain the magnitude of the uniformly distributed load q and the design parameters of the double-layer steel truss beam-arch composite system. The design parameters include the steel truss beam span L, the number of segments n of the double-layer steel truss beam, the length of the vertical member h, and the cross-sectional area A of the chord member. sxg , Vertical bar cross-sectional area A sg , the cross-sectional area A of the diagonal bar bxg The cross-sectional area A of the middle diagonal bar xg The cross-sectional area A of the suspension rod s The cross-sectional area A of the arch rib a Moment of inertia I of the arch rib section a The arch rise f, the elastic modulus E of the double-layer steel truss beam and arch rib, and the elastic modulus e of the hanger;

[0006] S2, Calculate the equivalent nodal load F eq , chord length a and diagonal length c; F eq =qL / (n+1), a = L / n, Define the tensile and compressive stiffness EA of the arch rib section. a =E×A a axial stiffness eA of the suspension rods =e×A s and the flexural stiffness EI of the arch rib a =E×I a ;

[0007] S3. Calculate the evaluation indicators, which include the mid-span deflection δ1 and the crown deflection δ2 of the steel truss beam.

[0008] The calculation model for the mid-span deflection δ1 of the steel truss beam is as follows:

[0009]

[0010] Where q represents the magnitude of the uniformly distributed load, L represents the span of the double-layer steel truss beam, and ξ b I represents the mid-span deflection coefficient of a double-layer steel truss beam. b ξ represents the equivalent moment of inertia of a double-layer steel truss beam. b and I b All values ​​are calculated; E represents the elastic modulus of the double-layer steel truss beam and arch rib, EI b EI represents the equivalent section bending stiffness of a steel truss. b =E×I b ;

[0011]

[0012] λ b1 =0;

[0013] λ b2 =30k a (1+k a )k sa +2304(1+k a ) 2 k f ;

[0014] λ b3 =5(7+12k) a )k a k sa +2304(1+6k a (1+k) a )k f ;

[0015] λ b4 =5(1+6k) a )k a k sa +320(1+6k a ) 2 k f ;

[0016] μ b1 =6(1+k)a ) 2 k sa ;

[0017] μ b2 = (7+18k) a (1+k) a )k sa +2304(1+k a ) 2 k f ;

[0018] μ b3 = (1+14k) a +18k a 2 )k sa +768(1+k a (1+6k) a )k f ;

[0019] μ b4 =(1+6k) a )k a k sa +64(1+6k a ) 2 k f ;

[0020] Where, λ b1 , λ b2 , λ b3 , λ b4 μ b1 μ b2 μ b3 and μ b4 All are transition parameters, k ba k represents the ratio of the section stiffness of a double-layer steel truss beam to the arch rib. a k represents the amplification factor for the axial deformation of the double-layer steel truss beam-arch composite system. sa This represents the ratio of the equivalent section stiffness of the hanger to the arch rib; k f This represents the shape factor of the arch axis, i.e., the rise-to-span ratio;

[0021] The calculation model for the crown deflection δ2 is as follows:

[0022]

[0023]

[0024] Where, ξ a λ represents the crown deflection coefficient. a1 , λ a2 , λ a3 μ a1 μa2 μ a3 and μ a4 All are transitional terms; μ a1 =μ b1 μ a2 =μ b2 μ a3 =μ b3 μ a4 =μ b4 ;

[0025] λ a1 =30(1+k) a )k a k sa ;

[0026] λ a2 =5(7+12k) a )k a k sa +384k f (1+k a (-1+24k) a );

[0027] λ a3 =5(1+6k) a )k a k sa +64k f (1+6k a (-1+24k) a ).

[0028] Preferred:

[0029]

[0030]

[0031] Where q represents the magnitude of the uniformly distributed load, L represents the span of the double-layer steel truss beam, δ represents the mid-span deflection of the double-layer steel truss beam under the equivalent nodal load of the double-layer full span; E represents the elastic modulus of the double-layer steel truss beam and the arch rib; a represents the chord length, h represents the vertical member length, c represents the diagonal member length; n represents the number of segments of the steel truss beam; A sxg A represents the cross-sectional area of ​​the chord member. sg A represents the cross-sectional area of ​​the vertical rod. bxg A represents the cross-sectional area of ​​the diagonal member. xg F represents the cross-sectional area of ​​the middle diagonal member. eq This represents the equivalent nodal load.

[0032] Preferred:

[0033]

[0034] Among them, EI a The EA represents the bending stiffness of the arch rib, and f represents the rise of the arch. a EA represents the tensile and compressive stiffness of the arch rib section. b For calculated values, EA b =2E×A sxg E represents the elastic modulus of the double-layer steel truss beam and the arch rib, A sxg This represents the cross-sectional area of ​​the chord.

[0035] Preferred:

[0036] k ba =EI b / EI a ;

[0037] k sa =EI s / EI a ;

[0038] k f =f / L;

[0039] EI s =ea s ×L 3 ;

[0040] ea s =eA s / a;

[0041] EI s EI represents the equivalent bending stiffness corresponding to the axial stiffness of the suspension rod. b This represents the equivalent section bending stiffness of the steel truss; eas is a transition term, L represents the span of the double-layer steel truss beam, a represents the chord length, and eA s This indicates the axial stiffness of the suspension rod.

[0042] Preferably, the evaluation index also includes the beam end rotation angle δ. c Its calculation model is as follows:

[0043]

[0044] λ c1 =156(1+k) a )k a k sa ;

[0045] λ c2 =(182k) a +336k a 2 )k sa +5376k f (1+12k a(1+k) a );

[0046] λ c3 = (26 + 180k) a )k a k sa +896k f (1+12k a (1+6k) a );

[0047] Where, λ c1 , λ c2 , λ c3 μ c1 μ c2 μ c3 and μ c4 All are transitional terms, μ c1 =μ b1 μ c2 =μ b2 μ c3 =μ b3 μ c4 =μ b4 .

[0048] Preferably, step S3 also includes calculating the membrane tension t:

[0049]

[0050] Preferably, the ratio of the membrane tension t to the uniformly distributed load q calculated in S3 is used as the load-sharing ratio of the arch rib. This invention also proposes a design method for a double-layer steel truss beam-arch composite system, including the following steps:

[0051] SA1. For a given uniformly distributed load q, develop multiple design schemes and obtain the design parameters for each scheme. These parameters include: steel truss beam span L, number of segments n in a double-layer steel truss beam, vertical member length h, and chord cross-sectional area A. sxg , Vertical bar cross-sectional area A sg , the cross-sectional area A of the diagonal bar bxg The cross-sectional area A of the middle diagonal bar xg The cross-sectional area A of the suspension rod s The cross-sectional area A of the arch rib a Moment of inertia I of the arch rib section a The arch rise f, the elastic modulus E of the double-layer steel truss beam and arch rib, and the elastic modulus e of the hanger;

[0052] SA2. Using the simplified evaluation method of the double-layer steel truss beam-arch combination system, the evaluation indicators of each design scheme are calculated in combination with the design parameters.

[0053] SA3. Obtain design solutions that meet the set requirements based on the evaluation indicators as alternative solutions;

[0054] SA4. Perform finite element simulations on each alternative scheme and select the optimal scheme based on the finite element simulation results.

[0055] Preferably, the requirement is set to satisfy any one of the following constraints 1-3; or a combination of any two of the following constraints 1-3; or simultaneously satisfy the following constraints 1-3.

[0056] Constraint 1: The mid-span deflection δ1 of the steel truss beam is greater than or equal to the first set value;

[0057] Constraint 2: The crown deflection δ2 is greater than or equal to the second set value;

[0058] Constraint 3: Beam end rotation angle δ c Greater than or equal to the third set value.

[0059] The present invention proposes a design system for a double-layer steel truss beam-arch composite system, which provides a carrier for the above-mentioned design method. The system includes a memory that stores a computer program. When the computer program is executed, it is used to implement the design method for the double-layer steel truss beam-arch composite system.

[0060] The advantages of this invention are:

[0061] (1) The present invention proposes a simplified evaluation method for a double-layer steel truss beam-arch composite system. This method, combined with a given computational model, can quickly calculate the mid-span deflection δ1 of the steel truss beam and the crown deflection δ2 of the arch in the double-layer steel truss beam-arch composite system, enabling rapid evaluation of bridge design schemes and facilitating preliminary selection of bridge design options. Before finite element modeling analysis, this invention can preliminarily determine the relationship between various structural parameters and structural mechanical properties, helping designers understand the mechanical properties of the structural system during the conceptual design phase and providing preliminary, reasonable design parameters.

[0062] (2) The present invention also provides the beam end rotation angle δ of the double-layer steel truss beam-arch composite system. c The calculation method for the load sharing ratio of the arch rib provides a more comprehensive evaluation model for the double-layer steel truss beam-arch composite system, which is convenient for application under different demand scenarios.

[0063] (3) The design method for the double-layer steel truss beam-arch composite system proposed in this invention first uses the simplified evaluation method for the double-layer steel truss beam-arch composite system provided by this invention to calculate the evaluation indicators of different design schemes, thereby achieving a rough screening of the design schemes; then, finite element simulation is used to simulate the small number of selected design schemes to select the optimal scheme. The expressions obtained by theoretical solution in this invention can intuitively reflect the relationship between each parameter and the structural mechanical performance, and can preliminarily determine the range of reasonable design parameters before obtaining accurate results through finite element modeling analysis.

[0064] (4) In this invention, the evaluation index is calculated by the given calculation model to screen the design scheme, which greatly reduces the workload of finite element simulation and improves the work efficiency; the selected scheme is subjected to finite element simulation to ensure the accuracy and safety of the final selected scheme. Attached Figure Description

[0065] Figure 1 A flowchart for a simplified evaluation method for a double-layer steel truss beam-arch composite system;

[0066] Figure 2 Flowchart of the design methodology for a double-layer steel truss beam-arch composite system;

[0067] Figure 3 This is a schematic diagram of a double-layer steel truss beam structure.

[0068] Figure 4 This is a schematic diagram of the double-layer steel truss beam-arch composite system structure;

[0069] Figure 5 The diagram shows the relationship between the truss height and the equivalent bending moment of inertia of a 110m span steel truss beam.

[0070] Figure 6 The diagram shows the relationship between the truss height and the equivalent bending moment of inertia of a 130m span steel truss beam.

[0071] Figure 7 This is a diagram showing the relationship between the truss height and the equivalent bending moment of inertia of a 150m span steel truss beam. Detailed Implementation

[0072] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0073] Simplified evaluation method for double-layer steel truss beam-arch composite system

[0074] Reference Figure 3 , Figure 4 The double-layer steel truss beam-arch composite system includes a double-layer steel truss beam 1, an arch 2, and a hanger 3. The double-layer steel truss beam includes chord members, diagonal members, and vertical members 13.

[0075] The chords include an upper chord 111 and a lower chord 112. The upper chord 111 is used to construct the upper deck of the double-layer steel truss beam, and the lower chord 112 is used to construct the lower deck of the double-layer steel truss beam.

[0076] The diagonal members are divided into side diagonal members 121 and middle diagonal members 122. Side diagonal members 121 refer to the diagonal members at the ends of the double-layer steel truss beam, and middle diagonal members 122 are the diagonal members between the side diagonal members at both ends of the double-layer steel truss beam. In other words, middle diagonal members 122 are all the diagonal members other than side diagonal members 121.

[0077] This embodiment proposes a simplified evaluation method for a double-layer steel truss beam-arch composite system. This method calculates evaluation indices for the double-layer steel truss beam under a uniformly distributed load of magnitude q. The evaluation indices include the mid-span deflection δ1, the arch crown deflection δ2, and the beam end rotation angle δ. c One or more of them.

[0078] In this embodiment, the calculation model for the mid-span deflection δ1 of the steel truss beam is shown below.

[0079]

[0080] Where q represents the magnitude of the uniformly distributed load, L represents the span of the double-layer steel truss beam, and ξ b EI represents the mid-span deflection coefficient of a double-layer steel truss beam. b EI represents the equivalent section bending stiffness of a steel truss. b =E×I b E represents the elastic modulus of the double-layer steel truss beam and the arch rib, I b ξ is the transition term to be calculated. b and EI b All values ​​are calculated.

[0081]

[0082] λ b1 =0;

[0083] λ b2 =30k a (1+k a )k sa +2304(1+k a ) 2 k f ;

[0084] λ b3 =5(7+12k) a )ka k sa +2304(1+6k a (1+k) a )k f ;

[0085] λ b4 =5(1+6k) a )k a k sa +320(1+6k a ) 2 k f ;

[0086] μ b1 =6(1+k) a ) 2 k sa ;

[0087] μ b2 = (7+18k) a (1+k) a )k sa +230491+k a ) 2 k f ;

[0088] μ b3 = (1+14k) a +18k a 2 )k sa +768(1+k a (1+6k) a )k f ;

[0089] μ b4 =(1+6k) a )k a k sa +64(1+6k a ) 2 k f ;

[0090] Where, λ b1 , λ b2 , λ b3 , λ b4 μ b1 μ b2 μ b3 and μ b4 All are transition parameters, k ba k represents the ratio of the section stiffness of a double-layer steel truss beam to the arch rib. a k represents the amplification factor for the axial deformation of the double-layer steel truss beam-arch composite system. saThis represents the ratio of the equivalent section stiffness of the hanger to the arch rib; k f This represents the shape coefficient of the arch axis, i.e., the rise-to-span ratio.

[0091]

[0092] k ba =EI b / EI a (1-4)

[0093] k sa =EI s / EI a (1-5)

[0094] k f =f / L; (1-6)

[0095] Among them, EI a EI represents the bending stiffness of the arch rib. a =E×I a I a The moment of inertia of the arch rib section is represented by f; the rise of the arch is represented by EA. a EA represents the tensile and compressive stiffness of the arch rib section. a =E×A a A a EA represents the cross-sectional area of ​​the arch rib. b For calculated values;

[0096] EA b =2E×A sxg (1-7)

[0097] E represents the elastic modulus of the double-layer steel truss beam and arch rib, A sxg Represents the cross-sectional area of ​​the chord;

[0098] EI s This represents the equivalent bending stiffness corresponding to the axial stiffness of the suspension rod.

[0099] EI s =ea s ×L 3 (1-8)

[0100] ea s =eA s / a; (1-9)

[0101] Among them, ea s As a transitional term, L represents the span of the double-layer steel truss beam, a represents the chord length, and eA s eA represents the axial stiffness of the boom. s =e×A s A sThis indicates the cross-sectional area of ​​the suspension rod.

[0102]

[0103]

[0104] Where q represents the magnitude of the uniformly distributed load, L represents the span of the double-layer steel truss beam, δ represents the mid-span deflection of the double-layer steel truss beam under the equivalent nodal load of the double-layer full span; E represents the elastic modulus of the double-layer steel truss beam and the arch rib; n represents the number of segments of the double-layer steel truss beam, a represents the chord length, h represents the vertical member length, and c represents the diagonal member length. a = L / n; A sxg A represents the cross-sectional area of ​​the chord member. sg A represents the cross-sectional area of ​​the vertical rod. bxg A represents the cross-sectional area of ​​the diagonal member. xg F represents the cross-sectional area of ​​the middle diagonal member. eq Indicates the equivalent nodal load; F eq =qL / (n+1).

[0105] The calculation model for the crown deflection δ2 is shown below.

[0106]

[0107]

[0108] Where q represents the magnitude of the uniformly distributed load, and L represents the span of the double-layer steel truss beam; EI b The equivalent section bending stiffness of the steel truss is represented by ξ, which is calculated using formula (1-3); a λ represents the crown deflection coefficient. a1 , λ a2 , λ a3 μ a1 μ a2 μ a3 and μ a4 All are transitional terms; μ a1 =μ b1 μ a2 =μ b2 μ a3 =μ b3 μ a4 =μ b4 ;

[0109] λ a1 =30(1+k) a )k a k sa ;

[0110] λ a2 =5(7+12k)a )k a k sa +384k f (1+k a (-1+24k) a );

[0111] λ a3 =5(1+6k) a )k a k sa +64k f (1+6k a (-1+24k) a );

[0112] k a k represents the amplification factor for the axial deformation of the double-layer steel truss beam-arch composite system. sa This represents the ratio of the equivalent section stiffness of the hanger to the arch rib; k f This represents the shape coefficient of the arch axis, i.e., the rise-to-span ratio.

[0113] Beam end rotation angle δ c The computational model is shown below.

[0114]

[0115] λ c1 =156(1+k) a )k a k sa ;

[0116] λ c2 =(182k) a +336k a 2 )k sa +5376k f (1+12k a (1+k) a );

[0117] λ c3 = (26 + 180k) a )k a k sa +896k f (1+12k a (1+6k) a );

[0118] Where q represents the magnitude of the uniformly distributed load, and L represents the span of the double-layer steel truss beam; EI b The equivalent section bending stiffness of the steel truss is represented by λ, which is calculated using formula (1-3); c1 , λ c2 , λc3 μ c1 μ c2 μ c3 and μ c4 All are transitional terms, μ c1 =μ b1 μ c2 =μ b2 μ c3 =μ b3 μ c4 =μ b4 .

[0119] like Figure 1 As shown, the simplified evaluation method for the double-layer steel truss beam-arch composite system proposed in this embodiment includes the following steps:

[0120] S1. Obtain the magnitude of the uniformly distributed load q and the design parameters of the double-layer steel truss beam-arch composite system. The design parameters include the steel truss beam span L, the number of segments n of the double-layer steel truss beam, the length of the vertical member h, and the cross-sectional area A of the chord member. sxg , Vertical bar cross-sectional area A sg , the cross-sectional area A of the diagonal bar bxg The cross-sectional area A of the middle diagonal bar xg The cross-sectional area A of the suspension rod s The cross-sectional area A of the arch rib a Moment of inertia I of the arch rib section a The arch rise f, the elastic modulus E of the double-layer steel truss beam and arch rib, and the elastic modulus e of the hanger;

[0121] S2, Calculate the equivalent nodal load F eq , chord length a and diagonal length c; F eq =qL / (n+1), a = L / n, Define the tensile and compressive stiffness EA of the arch rib section. a =E×A a axial stiffness eA of the suspension rod s =e×A s and the flexural stiffness EI of the arch rib a =E×I a ;

[0122] S3. Calculate the evaluation indicators, which include the mid-span deflection δ1 of the steel truss beam, the arch deflection δ2, and the beam end rotation angle δ. c One or more. The mid-span deflection δ1 of the steel truss beam is the mid-span deflection of the steel truss beam in the double-layer steel truss beam-arch composite system, and its calculation is given by formulas (1-1) to (1-11); the calculation of the arch top deflection δ2 is given by formulas (1-3) to (1-6) and formulas (2-1) to (2-2), and the beam end rotation δ... cFor calculation, refer to formulas (1-3) to (1-6) and formula (3-1).

[0123] In specific implementation, the evaluation indicators can also include the load sharing ratio of the arch ribs. The load sharing ratio of the arch ribs is the ratio of the membrane tension t to the magnitude of the uniformly distributed load q, that is, the load sharing ratio of the arch ribs = t / q.

[0124]

[0125] k sa This represents the equivalent section stiffness ratio of the hanger to the arch rib, and its calculation is given in formula (1-5); k a The amplification factor representing the axial deformation of the double-layer steel truss beam-arch composite system is given in formula (1-3); k ba The ratio of the section stiffness of the double-layer steel truss beam to the arch rib is given; its calculation is shown in formula (1-4); k f This represents the shape factor of the arch axis, i.e., the rise-to-span ratio, which is calculated using formula (1-6).

[0126] In this embodiment, when designing a double-layer steel truss beam-arch composite system, the design scheme can be determined according to the following steps SA1-SA3.

[0127] SA1. For a given uniformly distributed load q, develop multiple design schemes and obtain the design parameters for each scheme: steel truss beam span L, number of segments n in a double-layer steel truss beam, vertical member length h, and chord cross-sectional area A. sxg , Vertical bar cross-sectional area A sg , the cross-sectional area A of the diagonal bar bxg The cross-sectional area A of the middle diagonal bar xg The cross-sectional area A of the suspension rod s The cross-sectional area A of the arch rib a Moment of inertia I of the arch rib section a The arch rise f, the elastic modulus E of the double-layer steel truss beam and arch rib, and the elastic modulus e of the hanger.

[0128] SA2. A simplified evaluation method is adopted using a double-layer steel truss beam-arch combination system, and the evaluation indicators of each design scheme are calculated in combination with design parameters.

[0129] SA2. Obtain design solutions that meet the set requirements based on the evaluation indicators as alternative solutions;

[0130] Define the requirement as being satisfied by one of the following constraints, or a combination of any two of the following constraints, or by satisfying all three of the following constraints simultaneously.

[0131] Constraint 1: The mid-span deflection δ1 of the steel truss beam is greater than or equal to the first set value;

[0132] Constraint 2: The crown deflection δ2 is greater than or equal to the second set value;

[0133] Constraint 3: Beam end rotation angle δ c Greater than or equal to the third set value.

[0134] SA4. Perform finite element simulations on each alternative scheme, and select the optimal scheme based on the finite element simulation results, that is, the design scheme that best meets the target requirements.

[0135] The following example, using the design of a double-layer steel truss beam-arch composite system, verifies the effectiveness of the simplified evaluation method for the double-layer steel truss beam-arch composite system proposed in this invention.

[0136] In this embodiment, the structural parameters of the double-layer steel truss beam-arch composite system are as follows:

[0137] The beam span L = 150m; the distance from the top chord to the arch crown, i.e., the arch rise f = 28.444m; the truss height h = 12m; the chord length a = 9.375m; and the arch axis is a quadratic parabola. The arch rib section is box-shaped, the main beam is a steel truss, and the elastic modulus of the steel is E = 2.06e8kPa; the hangers are parallel high-strength steel wire cable hangers, and the elastic modulus of the hangers is e = 2.05e8kPa. The component section parameters are shown in Table 1.

[0138] Table 1 Geometric properties of structural cross sections

[0139]

[0140] It is worth noting that in this embodiment, the geometric properties (cross-sectional area and moment of inertia) of the middle diagonal member are the same as those of the vertical member.

[0141] In this embodiment, the main beam mid-span deflection δ1, arch crown deflection δ2, arch rib load sharing ratio, and beam end rotation δ corresponding to the design scheme are obtained through the method provided by this invention (hereinafter referred to as theoretical calculation) and the finite element simulation method (hereinafter referred to as finite element calculation), respectively. c In the finite element simulation, the load-sharing ratio of the arch rib is calculated by dividing the average axial force of the remaining hangers (excluding the edge hangers) by the inter-segment distance. The calculation results of the two methods in this embodiment are shown in Table 2 below.

[0142] Table 2 Comparison of Simplified Calculation Methods and Finite Element Calculation for Beam-Arch Composite Systems

[0143]

[0144]

[0145] As shown in Table 2, the errors of the two calculation methods are within the allowable range, proving the effectiveness of the simplified evaluation method for the double-layer steel truss beam-arch composite system provided by this invention.

[0146] In this embodiment, the equivalent sectional bending moment of inertia I is obtained by the method provided by this invention (hereinafter referred to as theoretical calculation) and the finite element simulation method (hereinafter referred to as finite element calculation), respectively. b And the design scheme corresponding to the mid-span deflection δ1 of the double-layer steel truss beam, the arch crown deflection δ2, the load sharing ratio of the arch ribs, and the beam end rotation δ c .

[0147] To further verify the effectiveness of the calculation model of this invention, this embodiment, based on known bridge parameters, changes the beam span L and chord length a to obtain the equivalent sectional bending moment of inertia I obtained from theoretical calculations and finite element calculations under different beam span L. b The calculation error is significant. It is worth noting that the length of the diagonal member changes with the length of the chord.

[0148] Given that the elastic modulus of the steel truss beam is E = 2.06e8 kPa, the cross-sectional characteristic parameters of each component are shown in Table 1.

[0149] When the beam span L = 110m and the chord length a = 9.167m, the equivalent section bending moment of inertia I b The trend of the truss height h changing is shown in Table 3.

[0150] Table 3: I when L = 110m b As the truss height h changes

[0151]

[0152] When the beam span L = 130m and the chord length a = 9.286m, the equivalent section bending moment of inertia I b The trend of the truss height h changing is shown in Table 4.

[0153] Table 4: I when L = 130m b As the truss height h changes

[0154]

[0155]

[0156] When the beam span L = 150m and the chord length a = 9.375m, the equivalent section bending moment of inertia I b The trend of the truss height h changing is shown in Table 5.

[0157] Table 5: I when L = 150m b As the truss height h changes

[0158]

[0159] To further verify the effectiveness of the theoretical calculations provided by this invention, the following further employs... Figure 2 The method shown compares the evaluation indicators of the two methods by combining different design structural parameters.

[0160] As shown in Tables 3-5, the two calculation methods have the same effect on the equivalent section bending moment of inertia I. b The relatively small calculation error demonstrates the effectiveness of this invention in calculating the equivalent cross-sectional bending moment of inertia I. b The effectiveness of [the system / mechanism].

[0161] Furthermore, in this embodiment, the number of segments n is adjusted for L = 110m, 130m, and 150m respectively, to obtain the equivalent sectional bending moment of inertia I corresponding to different numbers of segments n under the same beam span L. b As the truss height h changes, the results are as follows: Figure 5 , Figure 6 and Figure 7 As shown, the equivalent section bending moment of inertia I varies with the number of segments. b The consistent fluctuations in the truss height h demonstrate the effectiveness of this invention in calculating the equivalent section bending moment of inertia I. b The effectiveness.

[0162] In this embodiment, without changing the structure and material of the double-layer steel truss beam-arch combination system, the data comparison of theoretical calculation and finite element calculation under different truss heights is shown in Table 6, with beam span L = 150m, chord length a = 9.375m, and upper chord distance f = 28.444m from the arch top.

[0163] Table 6 Comparison of calculation methods and finite element calculation methods for beam-arch composite systems with different h values ​​when L = 150m.

[0164]

[0165] In this embodiment, without changing the structure and material of the double-layer steel truss beam-arch combination system, the data comparison between theoretical calculation and finite element calculation under different truss heights is shown in Table 7, with beam span L = 130m, chord length a = 9.286m, and upper chord distance f = 24.762m from the arch top.

[0166] Table 7 Comparison of calculation methods and finite element calculation methods for beam-arch composite systems with different h values ​​when L = 130m.

[0167]

[0168] As shown in Tables 6 and 7, when calculating the evaluation indicators using both methods, the errors corresponding to the mid-span deflection δ1 and the arch deflection δ2 of the main beam are both less than 12%, and the beam end rotation angle δ cThe corresponding errors were all less than 18%, proving the effectiveness of the invention.

[0169] To further verify the effectiveness of the computational model of the present invention, it should be noted that, for those skilled in the art, the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0170] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0171] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A simplified evaluation method for a double-layer steel truss beam-arch composite system, characterized in that, Includes the following steps: S1. Obtain the magnitude of the uniformly distributed load. q The design parameters for the double-layer steel truss arch composite system include the span of the double-layer steel truss beam. L Number of segments in a double-layer steel truss beam n Length of vertical bar h chord cross-sectional area A sxg , cross-sectional area of ​​vertical rod A sg , cross-sectional area of ​​the diagonal bar A bxg , cross-sectional area of ​​the middle diagonal bar A xg Cross-sectional area of ​​the suspension rod s Cross-sectional area of ​​arch ribs Moment of inertia of the arch rib section The height of the arch The elastic modulus of double-layer steel truss beams and arch ribs E And the elastic modulus of the rod e The length of the vertical members is the same as the height of the truss. S2, Calculate equivalent nodal loads F eq String length a and the length of the diagonal bar c ; , a=L / n, Define the tensile and compressive stiffness of the arch rib section. = Axial stiffness of the suspension rod and the bending stiffness of the arch rib = ; S3. Calculate the evaluation indicators, including the mid-span deflection of the steel truss beam. δ 1 and crown deflection ; Mid-span deflection of steel truss beam δ The calculation model for 1 is as follows: ； (1-1) in, q Indicates the magnitude of a uniformly distributed load. L Indicates the span of a double-layer steel truss beam. This represents the mid-span deflection coefficient of a double-layer steel truss beam. This represents the equivalent moment of inertia of the double-layer steel truss beam. and All values ​​are calculated. E This represents the elastic modulus of the double-layer steel truss beam and the arch rib. This represents the equivalent cross-sectional bending stiffness of the steel truss. = ; ； (1-2) ； ； ； ； ； ； ； ； in, , , , , , , and All are transition parameters. This indicates the ratio of the section stiffness of the double-layer steel truss beam to the arch rib. This represents the amplification factor for the axial deformation of the double-layer steel truss beam-arch composite system. This indicates the ratio of the equivalent section stiffness of the hanger to the arch rib; This represents the shape factor of the arch axis, i.e., the rise-to-span ratio; vault deflection The calculation model is as follows: ； (2-1) ； (2-2) in, Indicates the crown deflection coefficient; , , , , , and All of these are transitional terms; , , , ; ； ； 。 2. The simplified evaluation method for the double-layer steel truss beam-arch composite system as described in claim 1, characterized in that: ； (1-10) ； （1-11） in, q Indicates the magnitude of a uniformly distributed load. L Indicates the span of a double-layer steel truss beam. This represents the mid-span deflection of a double-layer steel truss beam under the action of a double-layer full-span equivalent nodal load. E This represents the elastic modulus of the double-layer steel truss beam and the arch rib. a Indicates the length of the chord. h Indicates the length of the vertical rod. c Indicates the length of the diagonal bar; n Indicates the number of segments in a steel truss beam; A sxg Represents the cross-sectional area of ​​the chord. A sg Represents the cross-sectional area of ​​the vertical rod. A bxg This represents the cross-sectional area of ​​the diagonal member. A xg Indicates the cross-sectional area of ​​the middle diagonal member; F eq This represents the equivalent nodal load.

3. The simplified evaluation method for the double-layer steel truss beam-arch composite system as described in claim 2, characterized in that: ； in, This indicates the bending stiffness of the arch rib. Indicates the arch's rise; This indicates the tensile and compressive stiffness of the arch rib section. For calculated values, ; E This represents the elastic modulus of the double-layer steel truss beam and the arch rib. A sxg This represents the cross-sectional area of ​​the chord.

4. The simplified evaluation method for the double-layer steel truss beam-arch composite system as described in claim 3, characterized in that: ； ； ； ； This represents the equivalent bending stiffness corresponding to the axial stiffness of the suspension rod. This indicates the equivalent cross-sectional bending stiffness of the steel truss. As a transitional term, L Indicates the span of a double-layer steel truss beam. a Indicates the length of the chord. This indicates the axial stiffness of the suspension rod.

5. The simplified evaluation method for the double-layer steel truss beam-arch composite system as described in claim 4, characterized in that, Evaluation indicators also include beam end rotation angle Its calculation model is as follows: ； (3-1) ； ； ； in, , , , , , and These are all transitional items. , , , .

6. The simplified evaluation method for the double-layer steel truss beam-arch composite system as described in claim 4, characterized in that, S3 also includes calculating membrane tension. t : 。 7. The simplified evaluation method for the double-layer steel truss beam-arch composite system as described in claim 1, characterized in that, Calculate membrane tension in S3 t With the magnitude of uniformly distributed load q The ratio is used as the load-sharing ratio of the arch rib.

8. A design method for a double-layer steel truss beam-arch composite system, characterized in that, Includes the following steps: SA1, for the set uniformly distributed load magnitude q Multiple design schemes were developed, and the design parameters for each scheme were obtained. The design parameters included: the span of the double-layer steel truss beam. L Number of segments in a double-layer steel truss beam n Length of vertical bar h chord cross-sectional area A sxg , cross-sectional area of ​​vertical rod A sg , cross-sectional area of ​​the diagonal bar A bxg , cross-sectional area of ​​the middle diagonal bar A xg Cross-sectional area of ​​the suspension rod s Cross-sectional area of ​​arch ribs Moment of inertia of the arch rib section The height of the arch The elastic modulus of double-layer steel truss beams and arch ribs E And the elastic modulus of the rod e ; SA2. Using the simplified evaluation method for the double-layer steel truss beam-arch composite system as described in any one of claims 1-7, the evaluation index of each design scheme is calculated in combination with the design parameters. SA3. Obtain design solutions that meet the set requirements based on the evaluation indicators as alternative solutions; SA4. Perform finite element simulations on each alternative scheme and select the optimal scheme based on the finite element simulation results.

9. The design method for the double-layer steel truss beam-arch composite system as described in claim 8, characterized in that, The requirement is defined as satisfying any one of the following constraints 1-3; or a combination of any two of the following constraints 1-3; or simultaneously satisfying the following constraints 1-3. Constraint 1: Mid-span deflection of steel truss beam δ 1 is greater than or equal to the first set value; Constraint 2: Crown deflection Greater than or equal to the second set value; Constraint 3: Beam end rotation Greater than or equal to the third set value.

10. A design system for a double-layer steel truss beam-arch composite system, characterized in that, It includes a memory containing a computer program, which, when executed, implements the design method for the double-layer steel truss beam-arch composite system as described in claim 8 or 9.

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