Method and system for determining length of main span steel segment of steel-concrete hybrid girder bridge

Abstract

The invention discloses a method and system for determining the length of a main span steel segment of a steel-concrete mixed girder bridge, and the method comprises the steps that a steel-concrete mixed system is called as a system I for short, a full-concrete system is called as a system II for short, and the system I and the system II have the same side span length; based on an integral equivalent method, enabling the system I to be equivalent to the system II, enabling the bending moments of the system I and the system II at the pier to be equal under the condition that only the self weight of the structure is considered, and finally determining the reasonable position of the combination section of the system I by establishing a control equation. According to the method, the length of the main span steel section of the system I is reasonably determined through an overall equivalent method, more reasonable bending moment distribution and simpler section and prestress design are achieved, additional ballasting of a side span is not needed, and the structural performance and economical efficiency are both achieved; by utilizing the advantages of light weight of the steel sections and low cost of the concrete sections, the method provides a clear calculation basis for bridge design, so that the design and construction of the large-span hybrid girder bridge are further optimized and innovated.

Description

Technical Field

[0001] This application relates to the technical field of the structural design of steel - concrete composite girder bridges, and particularly relates to a method and system for determining the length of the main - span steel segment of a steel - concrete composite girder bridge. Background Art

[0002] With the development of the economic society and the increase in steel production capacity, the application of steel - structure bridges has gradually increased. Steel - concrete composite girder bridges, which combine the respective advantages of steel and concrete, have good application prospects. As a kind of composite - structure bridge, the continuous rigid - frame steel - concrete composite girder bridge uses steel girders in the middle of the main span. Compared with traditional concrete continuous rigid - frame bridges, it not only makes a breakthrough in span but also improves the overall mechanical performance of the bridge structure.

[0003] However, the material cost and manufacturing cost of steel segments are both higher than those of concrete segments. Therefore, it is crucial to balance the performance and economy of the composite - beam structure. In bridge design, reasonably determining the length of the main - span steel segment of a continuous rigid - frame composite - beam bridge is of great significance for optimizing the structural stress and reducing costs. Reasonably determining the position of the joint section can not only give full play to the advantages of high strength and light weight of steel but also utilize the low - cost characteristics of concrete segments, thus achieving the optimal structural design and economic benefits.

[0004] In the prior art, most designs mainly determine the length of the main - span steel segment based on experience or simple parameter adjustment, lacking a systematic and scientific calculation method, resulting in inaccuracies in the design scheme and making it difficult to fully balance the mechanical performance and economy of the composite - beam bridge. Therefore, a systematic method based on mechanical principles is needed to determine the length of the main - span steel segment of the composite - beam bridge through scientific and reasonable calculations, optimize the mechanical performance and economy of the entire bridge, and achieve further breakthroughs in the field of long - span composite - beam bridges. Summary of the Invention

[0005] This application provides a method and system for determining the length of the main - span steel segment of a steel - concrete composite girder bridge, aiming to solve the problem that it is difficult to scientifically determine the length of the main - span steel segment of a steel - concrete composite girder bridge in the prior art.

[0006] To achieve the above - mentioned purpose, the technical solution of this application is as follows:

[0007] In the first aspect, this application provides a method for determining the length of the main - span steel segment of a steel - concrete composite girder bridge. Abbreviate the steel - concrete composite system as System I and the all - concrete system as System II. Both System I and System II include bridge piers, side spans, and main spans. The determination method includes:

[0008] The side span and the main span of the System I are the side span of the hybrid system and the main span of the hybrid system respectively. Both ends of the main span of the hybrid system are connected to the side span of the hybrid system through a pier. The main span of the hybrid system includes a steel segment in the center and concrete segments at both ends of the steel segment. The connection position between the steel segment and the concrete segment is the joint segment. The side span of the hybrid system includes a concrete segment. The steel segment is composed of several steel box girders, and the concrete segment is composed of several concrete box girders.

[0009] The side span and the main span of the System II are the side span of the all-concrete system and the main span of the all-concrete system respectively. Both ends of the main span of the all-concrete system are connected to the side span of the all-concrete system through a pier. The side span of the all-concrete system and the main span of the all-concrete system include concrete segments, and the concrete segments are composed of several concrete box girders.

[0010] Let the side span lengths of the System I and the System II be the same.

[0011] Based on the overall equivalent method, the System I is equivalent to the System II, so that the bending moments of the System I and the System II at the pier are equal when only considering the self-weight of the structure. By establishing a control equation, the reasonable position of the joint segment of the System I is finally determined.

[0012] Furthermore, the following parameters are defined:

[0013] L side,1 : The side span length of the System I;

[0014] L main,1 : The main span length of the System I;

[0015] L side,2 : The side span length of the System II;

[0016] L main,2 : The main span length of the System II;

[0017] L steel : The length of the steel segment of the main span of the System I;

[0018] M p,1 : The bending moment of the System I at the pier;

[0019] M p,2 : The bending moment of the System II at the pier;

[0020] In the System I, the length ratio of the side span to the main span is defined as λ1 = L side,1 / L main,1 , and the length ratio of the steel segment to the main span is defined as ξ = L steel / L main,1 ;

[0021] In the said System II, the length ratio of the side span to the main span is defined as λ2 = L side,2 / L main,2 , let L side,2 = L side,1 , that is, System II and System I have the same side span length;

[0022] The control equation of the overall equivalent method is M p,1 = M p,2 , that is, on the premise of only considering the self-weight of the structure, let the bending moment of System I at the pier be equal to the equivalent bending moment of System II at the pier. Thus, the reasonable value of the length ratio ξ of the steel segment to the main span and the relationship between the length ratio ξ of the steel segment to the main span and the length ratio λ1 of the side span to the main span can be determined, and then the reasonable position of the hybrid girder joint section can be determined.

[0023] Furthermore, it includes:

[0024] Calculate the self-weight bending moment of the said System II:

[0025] For the said System II, the beam height of the concrete box girder varies along the span according to a parabolic law, and the unit weight distribution of the concrete box girder is proportional to the change in the beam height. Then there is:

[0026] h(x) = h m + (h p - h m )(x / L2) α (1)

[0027] In formula (1), h(x) is the beam height of the concrete box girder at a distance x from the mid-span, h m is the beam height of the concrete box girder at the mid-span, h p is the beam height of the concrete box girder at the pier, L2 = L main,2 / 2, and α is the power of the parabolic equation for the change in beam height along the span;

[0028]

[0029] In formula (2), q(x) is the load intensity of the concrete box girder at a distance x from the mid-span, q cm = c·h m is the unit load intensity at the mid-span of the concrete box girder, and c is a constant;

[0030] Integrating formula (2) can obtain the equivalent bending moment of the said System II at the pier as:

[0031]

[0032] Calculate the self-weight bending moment of the said System I:

[0033] For the system I, the parabola of the steel segment and the concrete segment remains continuous, and q is defined s =β·q cm , that is, the unit weight q s of the steel box girder is β times the unit weight q cm of the concrete box girder with the same beam height. Then, we have:

[0034] h(x)=h m +(h p -h m )(x / L1) α (4)

[0035] where h(x) is the beam height of the steel box girder or the concrete box girder at the position x from the mid-span, and L1 = L main,1 / 2;

[0036]

[0037] where q(x c ) is the load intensity of the concrete box girder at the position x from the mid-span; q(x s ) is the load intensity of the steel box girder at the position x from the mid-span;

[0038] Integrating Equation (5) and taking the limit, the bending moment of the system I at the pier can be obtained as:

[0039]

[0040] Furthermore, it includes:

[0041] Determine the reasonable length of the steel segment of the system I:

[0042] According to the overall equivalent method, let M p,1 =M p,2 , and we can get:

[0043]

[0044] Then substitute λ1 = L side,1 / L main,1 and λ2 = L side,2 / L main,2 as well as L side,2 =L side,1 into Equation (7) and further simplify to get:

[0045]

[0046] Determine the reasonable value of ξ and the relationship between ξ and λ1 from Equation (8), and then the position of the joint section of the system I can be determined.

[0047] Further, the value range of λ2 is 0.55 to 0.65.

[0048] Further, the value range of β is 1 / 2 to 1 / 4.

[0049] In a second aspect, the present application provides a system for implementing the above determination method, including:

[0050] A parameter input module: used to input the known parameters of the system I and the system II;

[0051] A model construction module: used to construct models of the system I and the system II. The system I includes steel segments and concrete segments, and the system II includes concrete segments, and make the system I and the system II have the same side span length;

[0052] A control equation establishment module: establish control equations of the system I and the system II based on the overall equivalent method, so that the bending moments of the system I and the system II at the pier are equal;

[0053] A bending moment calculation module: calculate the bending moments of the system I and the system II at the pier respectively. The bending moment calculation of the system I needs to consider the continuity between the steel segment and the concrete segment;

[0054] A reasonable length calculation module: solve the length ratio of the steel segment to the main span in the system I based on the control equation, and determine the reasonable length of the steel segment and the position of the joint segment;

[0055] An output module: used to output the reasonable length of the steel segment in the system I and the position of the joint segment finally calculated.

[0056] In a third aspect, the present application provides an electronic device, which includes: a processor and a memory;

[0057] The memory is used to store one or more program instructions;

[0058] The processor is used to run one or more program instructions to execute the steps of the method for determining the length of the main span steel segment of the steel-concrete composite beam bridge as described above.

[0059] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored. It is characterized in that when the computer program is executed by a processor, it can implement the steps of the method for determining the length of the main span steel segment of the steel-concrete composite beam bridge as described above.

[0060] In a fifth aspect, the present application provides a computer program product, including a computer program. It is characterized in that when the computer program is executed by a processor, it can implement the steps of the method for determining the length of the main span steel segment of the steel-concrete composite beam bridge as described above.

[0061] The beneficial effects of this application are as follows:

[0062] This application provides a method and system for determining the length of the main span steel segment of a steel-concrete composite girder bridge. By using the overall equivalent method to determine the reasonable length of the main span steel segment of the steel-concrete composite girder bridge, the bending moment distribution of the whole bridge is made more reasonable, the cross-section design and prestress design of the composite girder are more convenient, and there is no need to set additional counterweights in the side span; in terms of structural performance and economy, this application gives full play to the advantages of the light weight of the steel segment and the low manufacturing cost of the concrete segment, realizing the optimization and balance of the structural performance of the composite girder; at the same time, this application provides a clear calculation basis, which can effectively determine the length of the steel segment under different bridge span arrangements, so as to further improve the span of the composite girder bridge and promote the development and innovation of the design and construction technologies of extra-long span composite girder bridges. Brief Description of the Drawings

[0063] Figure 1 It is the overall structural schematic diagram of the steel-concrete composite system of the embodiment of this application;

[0064] Figure 2 It is the overall structural schematic diagram of the equivalent all-concrete system of the embodiment of this application;

[0065] Figure 3 It is the schematic diagram of the equivalent bending moment calculation at the pier of the equivalent all-concrete system of the embodiment of this application;

[0066] Figure 4 It is the schematic diagram of the bending moment calculation at the pier of the steel-concrete composite system of the embodiment of this application;

[0067] Figure 5 It is the entity structural schematic diagram of the electronic device of another embodiment of this application.

[0068] Reference Signs:

[0069] 1-side span of the composite system; 2-main span of the composite system; 3-combined section; 4-steel segment; 5-concrete segment; 6-main pier; 7-side span of the all-concrete system; 8-main span of the all-concrete system;

[0070] 301-processor, 302-communication interface, 303-memory, 304-bus. Detailed Embodiments

[0071] Reference is made herein to the various aspects and features of this application with reference to the accompanying drawings.

[0072] It should be understood that various modifications can be made to the embodiments of the application herein. Therefore, the above description should not be construed as a limitation, but only as an example of an embodiment. Those skilled in the art will think of other modifications within the scope and spirit of this application.

[0073] The accompanying drawings, which are included in and form a part of this specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0074] These and other features of the present application will become apparent from the following description of the preferred forms of the embodiments given as non - limiting examples with reference to the accompanying drawings.

[0075] It should also be understood that although the present application has been described with reference to some specific examples, those skilled in the art can surely implement many other equivalent forms of the present application, which have the features as described in the claims and thus are all within the protection scope defined thereby.

[0076] When taken in conjunction with the accompanying drawings, the above and other aspects, features, and advantages of the present application will become more apparent in view of the following detailed description.

[0077] Specific embodiments of the present application will be described hereinafter with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of the present application and can be implemented in various ways. Well - known and / or repetitive functions and structures are not described in detail to avoid obscuring the present application with unnecessary or redundant details. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but rather serve as a basis for the claims and a representative basis for teaching those skilled in the art to use the present application in substantially any suitable detailed structure in a variety of ways.

[0078] This specification may use the phrases "in one embodiment", "in another embodiment", "in yet another embodiment", or "in other embodiments", each of which may refer to one or more of the same or different embodiments according to the present application.

[0079] A method for determining the length of the main - span steel segment of a steel - concrete composite beam bridge provided by an embodiment of the present application, a steel - concrete composite system (abbreviated as system I), as Figure 1 shown, includes a side - span of the composite system 1, a main - span of the composite system 2, and a pier 6; both ends of the main - span of the composite system 2 are respectively connected to the side - span of the composite system 1 through the pier 6; specifically in terms of structure, the main - span of the composite system 2 consists of a central steel segment 4 and concrete segments 5 located at both ends of the steel segment 4; the steel segment 4 is located at the central position of the main - span, bearing the main bending moment load in the middle of the main - span, while the concrete segments 5 are located on both sides of the steel segment 4, so that a joint segment 3 is formed between the segments, and the joint segment 3 is used for the transition between steel and concrete to ensure the continuity of the overall structure and the balance of the mechanical properties.

[0080] The side span 1 of the hybrid system is mainly composed of several concrete box girders, providing support and stability for the side span, and at the same time playing an advantage in the economy of the structure; the steel segment 4 is composed of several steel box girders, with high strength and stiffness, suitable for bearing the large bending moment requirements in the middle of the main span; by arranging the steel segment 4 at the central position of the main span, the steel-concrete hybrid system makes full use of the strength advantage of steel, providing the necessary high bearing capacity at the key positions of the main span, while the concrete segments 5 at both ends enhance the compressive performance of the structure while reducing the material cost, realizing the optimization of structural performance and economy.

[0081] Therefore, reasonably determining the length of the steel segment 4 and the position of the joint segment 3 is of great significance for achieving the best mechanical performance and economic benefits of the steel-concrete hybrid girder bridge.

[0082] See Figure 2 As shown, by adopting the overall equivalent method, the equivalent conversion of System I is carried out into a full-concrete system (abbreviated as System II). System II is composed of the side span 7 of the full-concrete system and the side span 8 of the full-concrete system, where the side span length of the side span 8 of the full-concrete system is the same as the side span length of the hybrid system side span 1 of System I.

[0083] Similarly, the side span 7 of the full-concrete system and the side span 8 of the full-concrete system in System II are composed of several concrete box girders.

[0084] Based on the overall equivalent method, System I is equivalent to System II, so that the bending moments of System I and System II at the pier are equal under the condition of only considering the self-weight of the structure. By establishing a control equation, the reasonable position of the joint segment of System I is finally determined.

[0085] See Figure 1-2 , specifically, the parameters are defined as follows:

[0086] L side,1 : The side span length of System I;

[0087] L main,1 : The main span length of System I;

[0088] L side,2 : The side span length of System II;

[0089] L main,2 : The main span length of System II;

[0090] L steel : The length of the steel segment in the main span of System I;

[0091] M p,1 : The bending moment of System I at the pier;

[0092] M p,2: The bending moment of the System II at the pier;

[0093] In the System I, the length ratio of the side span to the main span is defined as λ1 = L side,1 / L main,1 , and the length ratio of the steel segment to the main span is defined as ξ = L steel / L main,1 ;

[0094] In the System II, the length ratio of the side span to the main span is defined as λ2 = L side,2 / L main,2 , the value range of λ2 is 0.55 to 0.65. Let L side,2 = L side,1 , that is, the System II and the System I have the same side span length;

[0095] The control equation of the overall equivalent method is M p,1 = M p,2 , that is, on the premise of only considering the self - weight of the structure, make the bending moment of the System I at the pier equal to the equivalent bending moment of the System II at the pier. Thus, the reasonable value of the length ratio ξ of the steel segment to the main span and the relationship between the length ratio ξ of the steel segment to the main span and the length ratio λ1 of the side span to the main span can be determined, and then the reasonable position of the hybrid beam joint section can be determined.

[0096] It includes the following steps:

[0097] Step S1, referring to Figure 3 , calculate the self - weight bending moment of the System II:

[0098] For the System II, the beam height of the concrete box girder varies along the span in a parabolic law, and the unit weight distribution of the concrete box girder is proportional to the change in beam height. Then there is:

[0099] h(x) = h m +(h p - h m )(x / L2) α (1)

[0100] In formula (1), h(x) is the beam height of the concrete box girder at a distance x from the mid - span, h m is the beam height of the concrete box girder at the mid - span, h p is the beam height of the concrete box girder at the pier, L2 = L main,2 / 2, and α is the power of the parabolic equation of the beam height change along the span;

[0101]

[0102] In formula (2), q(x) is the load intensity of the concrete box girder at a distance x from the mid - span, q cm = c·h mq is the unit load intensity at the mid-span of the concrete box girder, and c is a constant;

[0103] Integrating Equation (2) gives the equivalent moment of System II at the pier as:

[0104]

[0105] Step S2. Refer to Figure 4 and calculate the self-weight moment of System I:

[0106] For System I, the parabolas of the steel segment and the concrete segment are continuous. At the same time, define q s = β·q cm That is, the unit weight q s of the steel box girder is β times the unit weight q cm of the concrete box girder with the same beam height. Generally, β is taken as 1 / 3. Then we have:

[0107] h(x) = h m +(h p - h m )(x / L1) α (4)

[0108] In the formula, h(x) is the beam height of the steel box girder or the concrete box girder at the position x from the mid-span, and L1 = L main,1 / 2;

[0109]

[0110] In the formula, q(x c ) is the load intensity of the concrete box girder at the position x from the mid-span; q(x s ) is the load intensity of the steel box girder at the position x from the mid-span;

[0111] Integrating Equation (5) and taking the limit gives the moment of System I at the pier as:

[0112]

[0113] Step S3. Determine the reasonable length of the steel segment of System I:

[0114] According to the overall equivalent method, let M p,1 = M p,2 , and we can get:

[0115]

[0116] Then substitute λ1 = L side,1 / L main,1 and λ2 = L side,2 / L main,2 and Lside,2 = L side,1 Substituting into Equation (7) and further simplifying gives:

[0117]

[0118] By determining the reasonable value of ξ and the relationship between ξ and λ1 from Equation (8), the position of the combined section of the system I can be determined.

[0119] The embodiment of the present application provides a system for determining the length of the steel section of the main span of a steel-concrete composite girder bridge, which corresponds to the steps of the method for determining the length of the steel section of the main span of a steel-concrete composite girder bridge in the embodiment, and realizes the organic coordination between modules. The system includes the following modules:

[0120] Parameter input module: used to input the known parameters of the system I and the system II. By inputting these parameters, the system provides a data basis for subsequent model construction and calculation.

[0121] Model construction module: This module is responsible for constructing the structural models of the system I and the system II. The system I is a steel-concrete composite system, including the steel section at the central position of the main span and the concrete sections at both ends; the system II is an equivalent all-concrete system; the model construction module ensures that the system I and the system II have the same side span length for overall equivalent analysis and comparison.

[0122] Control equation establishment module: Based on the overall equivalence method, the control equation establishment module constructs the control equations of the system I and the system II to make the bending moments at the piers of the two systems equal; in this step, the core of the equivalence method is to equate the bending moment of the composite system I to the bending moment of the all-concrete system II; the control equations established by this module provide a basis for solving for the reasonable length calculation module.

[0123] Bending moment calculation module: Calculate the bending moments at the piers of the system I and the system II respectively. The calculation of the bending moment of the system I needs to consider the continuity between the steel section and the concrete section;

[0124] Reasonable length calculation module: By solving the control equations, obtain the reasonable length ratio of the steel section in the system I to the main span. Based on this length ratio, the module further determines the reasonable length of the steel section and the position of the combined section, so that the steel section can effectively bear the main bending moment load at the central position of the main span, and make the transition between steel and concrete smooth, ensuring the stability and continuity of the overall structure.

[0125] Output module: used to present the final calculation results, including the reasonable length of the steel section in the system I and the specific position of the combined section.

[0126] Based on the same inventive concept, embodiments of the present disclosure also provide an electronic device for a method of determining the length of the main-span steel segment of a steel-concrete composite girder bridge. Figure 5 FIG. Figure 5 is a schematic structural diagram of the electronic device provided by the embodiments of the present invention. The electronic device may include: a processor 301, a communications interface 302, a memory 303, and a bus 304. Among them, the processor 301, the communications interface 302, and the memory 303 communicate with each other through the bus 304. The processor 301 may call a computer program stored on the memory 303 and executable on the processor 301 to execute the method for determining the length of the main-span steel segment of the steel-concrete composite girder bridge provided in the foregoing embodiments. For example, it includes: the side span and the main span of the system I are respectively a hybrid system side span and a hybrid system main span, and both ends of the hybrid system main span are connected to the hybrid system side span through a pier; the hybrid system main span includes a steel segment in the center and concrete segments at both ends of the steel segment, and the connection position between the steel segment and the concrete segment is a joint section; the hybrid system side span includes a concrete segment; the steel segment is composed of several steel box girders, and the concrete segment is composed of several concrete box girders; the side span and the main span of the system II are respectively a full-concrete system side span and a full-concrete system main span, and both ends of the full-concrete system main span are connected to the full-concrete system side span through a pier, and the full-concrete system side span and the full-concrete system main span include concrete segments, and the concrete segments are composed of several concrete box girders; make the system I and the system II have the same side span length; based on the overall equivalent method, equivalent the system I to the system II, so that the bending moments of the system I and the system II at the pier are equal when only considering the self-weight of the structure, and by establishing a control equation, finally determine the reasonable position of the joint section of the system I.

[0127] In addition, when the logical instructions in the foregoing memory 303 can be implemented in the form of software functional units and sold or used as an independent product, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiments of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media such as a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk, or an optical disc that can store program codes.

[0128] Based on the same inventive concept, an embodiment of the present disclosure further provides a computer program product, including a computer program, which when executed by a processor can implement the method for determining the length of the main span steel segment of a steel-concrete composite girder bridge as described above.

[0129] The above description is only a preferred embodiment of the present disclosure and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of disclosure involved in the present disclosure is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosure concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present disclosure.

[0130] In addition, although the operations are depicted in a particular order, this should not be construed as requiring that the operations be performed in the particular order shown or in sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present disclosure. Certain features described in the context of separate embodiments may also be implemented combinatorially in a single embodiment. Conversely, the various features described in the context of a single embodiment may also be implemented separately or in any suitable sub-combination in multiple embodiments.

Claims

1. Method for determining the length of the steel segment of the main span of a steel-concrete composite girder bridge. The steel-concrete composite system is abbreviated as System I, and the all-concrete system is abbreviated as System II. Both System I and System II include bridge piers, side spans, and main spans, and are characterized in that, The determination method includes: The side span and the main span of the System I are respectively the side span of the hybrid system and the main span of the hybrid system. Both ends of the main span of the hybrid system are connected to the side span of the hybrid system through a pier. The main span of the hybrid system includes a steel segment in the center and concrete segments at both ends of the steel segment. The connection position between the steel segment and the concrete segment is the joint segment. The side span of the hybrid system includes a concrete segment. The steel segment is composed of several steel box girders, and the concrete segment is composed of several concrete box girders. The side span and the main span of the System II are respectively the side span of the all-concrete system and the main span of the all-concrete system. Both ends of the main span of the all-concrete system are connected to the side span of the all-concrete system through a pier. The side span of the all-concrete system and the main span of the all-concrete system include concrete segments, and the concrete segments are composed of several concrete box girders. Make the side span lengths of the System I and the System II the same. Based on the overall equivalent method, the System I is equivalent to the System II, so that the bending moments of the System I and the System II at the pier are equal when only considering the self-weight of the structure. By establishing a control equation, the reasonable position of the joint segment of the System I is finally determined.

2. The method for determining the length of the main span steel segment of a steel-concrete composite beam bridge according to claim 1, wherein Define the parameters as follows: L side,1 : The side span length of the system I; L main,1 : The main span length of the system I; L side,2 : The side span length of the System II; L main,2 : the main span length of the system II; L steel : the length of the steel segment of the main span of the System I; M p,1 : The bending moment of the system I at the pier; M p,2 : The bending moment of the System II at the pier; In the system I, the length ratio of the side span to the main span is defined as λ1 = L side,1 / L main,1 , and the length ratio of the steel segment to the main span is defined as ξ = L steel / L main,1 ; In the said System II, the length ratio of the side span to the main span is defined as λ2 = L side,2 / L main,2 , let L side,2 = L side,1 , that is, System II has the same side span length as System I; The governing equation of the overall equivalent method is M p,1 = M p,2 , that is, on the premise of only considering the self-weight of the structure, the bending moment of the system I at the pier is made equal to the equivalent bending moment of the system II at the pier. From this, the reasonable value of the length ratio ξ of the steel segment to the main span and the relationship between the length ratio ξ of the steel segment to the main span and the length ratio λ1 of the side span to the main span can be determined. Furthermore, the reasonable position of the hybrid girder joint section can be determined.

3. The method for determining the length of the main span steel segment of a steel-concrete composite beam bridge according to claim 2, characterized in that, including: Calculate the self-weight bending moment of the System II: For the System II, the beam height of the concrete box girder follows a parabolic law along the span, and the unit weight distribution of the concrete box girder is proportional to the change in beam height. Then there is: h(x) = h m + (h p - h m )(x / L2) α (1) In Equation (1), h(x) is the beam height of the concrete box girder at x from the mid-span, h m is the beam height of the concrete box girder at the mid-span, h p is the beam height of the concrete box girder at the pier, L2 = L main,2 / 2, and α is the power of the parabolic equation for the variation of the beam height along the span; In Equation (2), q(x) is the load intensity at a distance x from the mid-span of the concrete box girder, and q cm = c·h m is the unit load intensity at the mid-span of the concrete box girder, and c is a constant; Integrating Equation (2) can obtain the equivalent bending moment of the System II at the pier as: Calculate the self-weight bending moment of the System I: For the system I, the parabolas of the steel segment and the concrete segment remain continuous, and at the same time, q is defined s = β·q cm , that is, the unit weight q s of the steel box girder is β times that of the unit weight q cm of the concrete box girder with the same beam height. Then, we have: h(x) = h m +(h p -h m )(x / L1) α (4) where h(x) is the beam height at the position x from the mid-span of the steel box girder or concrete box girder, and L1 = L main,1 / 2; where \(q(x c )\) is the load intensity at the position \(x\) from the mid-span of the concrete box girder; \(q(x s )\) is the load intensity at the position \(x\) from the mid-span of the steel box girder; Integrating Equation (5) and taking the limit can obtain the bending moment of the System I at the pier as:

4. The method for determining the length of the main span steel segment of a steel-concrete composite beam bridge according to claim 3, wherein including: Determine the reasonable length of the steel segment of the System I: According to the overall equivalent method, let M p,1 = M p,2 , we can obtain: Then substitute λ1 = L side,1 / L main,1 and λ2 = L side,2 / L main,2 as well as L side,2 = L side,1 into Equation (7) and further simplify to obtain: Determining the reasonable value of ξ and the relationship between ξ and λ1 from Equation (8) can determine the position of the joint segment of the System I.

5. The method for determining the length of the main span steel segment of a steel-concrete composite beam bridge according to claim 2, wherein, The value range of λ2 is 0.55 - 0.

65.

6. The method for determining the length of the main span steel segment of a steel-concrete composite beam bridge according to claim 3, wherein The value range of β is 1 / 2 - 1 / 4.

7. The method for determining the length of the main span steel segment of a steel-concrete composite beam bridge according to claim 1, wherein The system for implementing the determination method includes: Parameter input module: used to input the known parameters of the System I and the System II. Model construction module: used to construct the models of the System I and the System II. The System I includes a steel segment and a concrete segment, and the System II includes a concrete segment, and make the side span lengths of the System I and the System II the same. Control equation establishment module: based on the overall equivalent method, establish the control equations of the System I and the System II, so that the bending moments of the System I and the System II at the pier are equal. Bending moment calculation module: calculate the bending moments of the System I and the System II at the pier respectively. The bending moment calculation of the System I needs to consider the continuity between the steel segment and the concrete segment. Reasonable length calculation module: based on the solution of the control equation, obtain the length ratio of the steel segment to the main span in the System I, and determine the reasonable length of the steel segment and the position of the joint segment. Output module: used to output the reasonable length of the steel segment and the position of the joint segment of the System I finally calculated.

8. An electronic device, characterized in that, The device includes: a processor and a memory; The memory is used to store one or more program instructions; The processor is configured to run one or more program instructions to perform the steps of the method for determining the length of the steel segment of the main span of the steel-concrete composite beam bridge according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it can implement the steps of the method for determining the length of the steel segment of the main span of the steel-concrete composite beam bridge according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it can implement the steps of the method for determining the length of the steel segment of the main span of the steel-concrete composite beam bridge according to any one of claims 1 to 6.

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