Method for obtaining parameters of steel truss concrete composite beam

Abstract

The application provides a method for obtaining parameters of a steel truss concrete composite beam, comprising the following steps: collecting relevant data of a composite beam to be obtained by a testing tool, wherein the relevant data comprises a sectional area of upper concrete, a sectional area of a lower chord steel structure, a bending stiffness of the upper concrete, a distance between the upper concrete and the lower chord steel structure, an elastic modulus of the upper concrete, and an elastic modulus of the lower chord steel structure; and obtaining parameters of the composite beam according to the relevant data and a preset obtaining formula, wherein the parameters comprise a bending stiffness of the composite beam, an internal force of the composite beam, a deformation of the composite beam, and a limit bearing capacity of the composite beam. The method makes the obtaining of the parameters of the steel truss concrete composite beam not follow the obtaining mode of a solid-web composite beam or a steel truss, and improves the accuracy of the parameters of the steel truss concrete composite beam.

Description

Technical Field

[0001] This application belongs to the field of construction, and in particular relates to a method for obtaining parameters of steel truss concrete composite beams. Background Technology

[0002] Steel truss-concrete composite beams offer advantages such as high overall and local stiffness, low steel consumption, structural transparency, and ease of construction, leading to their increasingly widespread application. Currently, there is no theoretical calculation method specifically for the stiffness, internal forces, and ultimate bearing capacity of steel truss-concrete composite beams; calculations can only be approximated as solid-web composite beams or steel trusses. If calculated as a solid-web composite beam, its section shear force and ultimate bearing capacity cannot be calculated. If calculated as a steel truss, the bending and shear resistance of the concrete slab itself cannot be considered, resulting in significant calculation errors. Summary of the Invention

[0003] The main objective of this invention is to provide a method for obtaining parameters of steel truss concrete composite beams, which improves the accuracy of the parameters by obtaining them in a way that differs from that of solid-web composite beams or steel trusses.

[0004] Firstly, a method for obtaining parameters of steel truss concrete composite beams is provided, the method comprising:

[0005] The relevant data of the composite beam to be acquired are collected by testing tools. The relevant data includes: the cross-sectional area of ​​the upper concrete, the cross-sectional area of ​​the lower chord steel structure, the bending stiffness of the upper concrete, the distance between the upper concrete and the lower chord steel structure, the elastic modulus of the upper concrete, and the elastic modulus of the lower chord steel structure.

[0006] The parameters of the composite beam are obtained based on the relevant data and the preset acquisition formula. The parameters include: the bending stiffness of the composite beam, the internal force of the composite beam, the deformation of the composite beam, and the ultimate bearing capacity of the composite beam.

[0007] In one possible implementation, obtaining the flexural stiffness of the composite beam based on the relevant data and a preset acquisition formula includes:

[0008] According to the preset formula for the bending stiffness of composite beams Obtain the flexural stiffness of the composite beam, where E c For the elastic modulus of the upper layer concrete, A c For the cross-sectional area of ​​the upper concrete layer, I c For the flexural stiffness of the upper concrete, E s For the elastic modulus of the lower chord steel structure, A s For the cross-sectional area of ​​the lower chord steel structure, I s This refers to the bending stiffness of the upper steel structure;

[0009] According to Ec I c Much larger than E s I s The formula for the bending stiffness of the composite beam is simplified to: ,in, The elastic modulus ratio of steel to concrete, This represents the ratio of the cross-sectional area of ​​the lower chord steel structure to the cross-sectional area of ​​the upper concrete layer.

[0010] In another possible implementation, obtaining the flexural stiffness of the composite beam based on the relevant data and a preset formula further includes:

[0011] According to A c Much larger than A s The formula for the bending stiffness of the composite beam is simplified to: .

[0012] In another possible implementation, obtaining the axial force and bending moment distribution of the composite beam based on the relevant data and a preset acquisition formula includes:

[0013] According to the preset axial force and bending moment distribution formula Obtain the distribution of axial force and bending moment of the composite beam, where M is the bending moment of the composite beam, N is the axial force of the composite beam section, and M c The bending moment of the concrete panel, N c The total axial force of the concrete panel, N c1 The axial force generated by M, N c2 The axial force generated by N, N s The total axial force of the lower chord steel structure, N s1 The axial force generated by M, N s2 The sum of the axial force generated by N and the axial force generated by the bending moment M is 0, N c1 +N s1 =0;

[0014] The axial force is distributed according to stiffness. And distribute the bending moment according to the stiffness. get:

[0015]

[0016]

[0017]

[0018]

[0019]

[0020] .

[0021] In another possible implementation, if the composite beam structure is subjected to a concentrated load at mid-span, the step of obtaining the internal forces of the composite beam based on the relevant data and a preset acquisition formula includes:

[0022] Obtain the centroidal bending moment of the bridge deck at the nth span of the composite beam. ;

[0023] Will Substitution Obtain the axial force of the (n+1)th lower chord. Axial force of the nth lower chord of the steel structure Axial force of the diagonal web member at the nth internode Axial force of the vertical web member at the nth internode ;

[0024] The shear force at the i-th end of the upper concrete layer of the n-th intersection is obtained based on the axial force of the (n+1)-th lower chord, the axial force of the n-th lower chord, the axial force of the diagonal web member at the n-th intersection, and the axial force of the vertical web member at the n-th intersection. Bending moment Axial force .

[0025] In another possible implementation, if the composite beam structure is subjected to a uniformly distributed load, the step of obtaining the internal forces of the composite beam based on the relevant data and a preset acquisition formula includes:

[0026] Obtain the axial force of the nth lower chord of the composite beam. Axial force of the diagonal web member at the nth internode Axial force of the vertical web member at the nth internode ;

[0027] The shear force at the i-th end of the upper concrete layer of the n-th intersection is obtained based on the axial force of the n-th lower chord, the axial force of the diagonal web member at the n-th intersection, and the axial force of the vertical web member at the n-th intersection. Bending moment Axial force .

[0028] In another possible implementation, obtaining the bearing capacity of the composite beam based on the relevant data and a preset acquisition formula includes:

[0029] Obtain the compressive stress f when the upper layer of concrete reaches its ultimate strength. c And obtain the force f when the lower chord steel reaches its yield strength. y and in When, obtain the f c f yAs the yield flexural capacity of the composite beam; and,

[0030] According to the formula Obtain the ultimate flexural capacity of the composite beam, wherein M u This refers to the ultimate bending capacity. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below.

[0032] Figure 1 This is a flowchart illustrating a method for obtaining parameters of a steel truss concrete composite beam according to an embodiment of the present invention. Detailed Implementation

[0033] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar modules or modules having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting the invention.

[0034] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this application means the presence of the stated features, integers, steps, operations, modules, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, modules, components, and / or groups thereof. It should be understood that when we say a module is “connected” or “coupled” to another module, it can be directly connected or coupled to the other module, or there may be an intermediate module. Furthermore, “connected” or “coupled” as used herein can include wireless connection or wireless coupling. The term “and / or” as used herein includes all or any of the modules and all combinations thereof of one or more associated listed items.

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the implementation of this application will be described in further detail below with reference to the accompanying drawings.

[0036] The technical solutions of this application and how they solve the aforementioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0037] like Figure 1The diagram shows a flowchart of a method for obtaining parameters of a steel truss concrete composite beam according to an embodiment of the present invention. The method includes:

[0038] Step 101: Collect relevant data of the composite beam to be acquired using testing tools. The relevant data includes: the cross-sectional area of ​​the upper concrete layer, the cross-sectional area of ​​the lower chord steel structure, the bending stiffness of the upper concrete layer, the distance between the upper concrete layer and the lower chord steel structure, the elastic modulus of the upper concrete layer, and the elastic modulus of the lower chord steel structure.

[0039] Step 102: Obtain the parameters of the composite beam according to the relevant data and the preset acquisition formula. The parameters include: the bending stiffness of the composite beam, the internal force of the composite beam, the deformation of the composite beam, and the ultimate bearing capacity of the composite beam.

[0040] In this embodiment of the invention, the steel truss concrete composite beam is composed of an upper layer of concrete and a lower chord steel structure. In order to obtain the parameters of the steel truss concrete composite beam, it is necessary to obtain the relevant data of the steel truss concrete composite beam. The relevant data is obtained by a testing tool set on the steel truss concrete composite beam. The relevant data includes, but is not limited to: the cross-sectional area of ​​the upper layer of concrete, the cross-sectional area of ​​the lower chord steel structure, the bending stiffness of the upper layer of concrete, the distance between the upper layer of concrete and the lower chord steel structure, the elastic modulus of the upper layer of concrete, and the elastic modulus of the lower chord steel structure.

[0041] After obtaining the relevant data, the data is substituted into the corresponding calculation formulas to obtain the parameters of the steel truss concrete composite beam.

[0042] In this embodiment of the invention, relevant data of the composite beam to be acquired is collected using testing tools. This data includes: the cross-sectional area of ​​the upper concrete layer, the cross-sectional area of ​​the lower chord steel structure, the flexural stiffness of the upper concrete layer, the distance between the upper concrete layer and the lower chord steel structure, the elastic modulus of the upper concrete layer, and the elastic modulus of the lower chord steel structure. Based on this data and a preset acquisition formula, the parameters of the composite beam are obtained. These parameters include: the flexural stiffness of the composite beam, the internal forces of the composite beam, and the ultimate bearing capacity of the composite beam. This method improves the accuracy of the parameters of the steel truss concrete composite beam by deviating from the methods used for solid-web composite beams or steel trusses.

[0043] The step of obtaining the flexural stiffness of the composite beam based on the relevant data and a preset formula includes:

[0044] According to the preset formula for the bending stiffness of composite beams Obtain the flexural stiffness of the composite beam, where E c For the elastic modulus of the upper layer concrete, A c For the cross-sectional area of ​​the upper concrete layer, I cFor the flexural stiffness of the upper concrete, E s For the elastic modulus of the lower chord steel structure, A s For the cross-sectional area of ​​the lower chord steel structure, I s This refers to the bending stiffness of the upper steel structure;

[0045] According to E c I c Much larger than E s I s The formula for the bending stiffness of the composite beam is simplified to: ,in, The elastic modulus ratio of steel to concrete, This represents the ratio of the cross-sectional area of ​​the lower chord steel structure to the cross-sectional area of ​​the upper concrete layer.

[0046] As an optional embodiment of the present invention, the step of obtaining the flexural stiffness of the composite beam based on the relevant data and the preset acquisition formula further includes:

[0047] According to A c Much larger than A s The formula for the bending stiffness of the composite beam is simplified to: .

[0048] The step of obtaining the axial force and bending moment distribution of the composite beam based on the relevant data and a preset acquisition formula includes:

[0049] According to the preset axial force and bending moment distribution formula Obtain the distribution of axial force and bending moment of the composite beam, where M is the bending moment of the composite beam, N is the axial force of the composite beam section, and M c The bending moment of the concrete panel, N c The total axial force of the concrete panel, N c1 The axial force generated by M, N c2 The axial force generated by N, N s The total axial force of the lower chord steel structure, N s1 The axial force generated by M, N s2 The sum of the axial force generated by N and the axial force generated by the bending moment M is 0, N c1 +N s1 =0;

[0050] The axial force is distributed according to stiffness. And distribute the bending moment according to the stiffness. get:

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057] Wherein, if the composite beam structure is subjected to a concentrated load at mid-span, the step of obtaining the internal forces of the composite beam based on the relevant data and a preset acquisition formula includes:

[0058] Obtain the centroidal bending moment of the bridge deck at the nth span of the composite beam. ;

[0059] Will Substitution Obtain the axial force of the (n+1)th lower chord. Axial force of the nth lower chord of the steel structure Axial force of the diagonal web member at the nth internode Axial force of the vertical web member at the nth internode ;

[0060] The shear force at the i-th end of the upper concrete layer of the n-th intersection is obtained based on the axial force of the (n+1)-th lower chord, the axial force of the n-th lower chord, the axial force of the diagonal web member at the n-th intersection, and the axial force of the vertical web member at the n-th intersection. Bending moment Axial force .

[0061] Wherein, if the composite beam structure is subjected to uniformly distributed load, the step of obtaining the internal forces of the composite beam based on the relevant data and a preset acquisition formula includes:

[0062] Obtain the axial force of the nth lower chord of the composite beam. Axial force of the diagonal web member at the nth internode Axial force of the vertical web member at the nth internode ;

[0063] The shear force at the i-th end of the upper concrete layer of the n-th intersection is obtained based on the axial force of the n-th lower chord, the axial force of the diagonal web member at the n-th intersection, and the axial force of the vertical web member at the n-th intersection. Bending moment Axial force .

[0064] The step of obtaining the deformation of the composite beam based on the relevant data and a preset acquisition formula includes:

[0065] The deflection f caused by slip deformation is obtained by reducing the flexural stiffness of the composite beam section. s ;

[0066] According to the preset composite beam deformation calculation formula Obtain the total deformation of the composite beam, where f is the total deformation of the composite beam, f0 is the bending deformation without considering slip effect, and f w The deflection caused by the axial deformation of the web member, f s This refers to the deflection caused by slip deformation;

[0067] Bending stiffness of composite sections without considering bond slip:

[0068]

[0069] Bending stiffness of composite sections considering bond slip:

[0070]

[0071] Calculate according to Formula 14.4.3 of the "Standard for Design of Steel Structures (GB 50017-2017)".

[0072] The shear deformation deflection of the web members is mainly caused by the axial compression of the web members under shear force. According to the principle of virtual work, the vertical deflection under uniformly distributed load is as follows:

[0073]

[0074] Internal forces in the web members under load;

[0075] Internal forces in the web members under a unit load at mid-span;

[0076] Cross-sectional area of ​​the web member

[0077] Length of web member

[0078] The internal forces of the web members can be calculated using the method described above.

[0079] The vertical stiffness of the simply supported steel truss-concrete composite beam is:

[0080]

[0081]

[0082] Where L is the span of the simply supported beam.

[0083] The step of obtaining the bearing capacity of the composite beam based on the relevant data and a preset formula includes:

[0084] Obtain the compressive stress f when the upper layer of concrete reaches its ultimate strength. c And obtain the force f when the lower chord steel reaches its yield strength. y and in When, obtain the f c f y As the yield flexural capacity of the composite beam; and,

[0085] According to the formula Obtain the ultimate flexural capacity of the composite beam, wherein M u This refers to the ultimate bending capacity.

[0086] It should be understood that although the steps in the flowcharts of the accompanying figures are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the accompanying figures may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0087] The above description is only a partial implementation of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for obtaining parameters of a steel truss concrete composite beam, characterized in that, The method includes: The relevant data of the composite beam to be acquired are collected by testing tools. The relevant data includes: the cross-sectional area of ​​the upper concrete, the cross-sectional area of ​​the lower chord steel structure, the bending stiffness of the upper concrete, the distance between the upper concrete and the lower chord steel structure, the elastic modulus of the upper concrete, and the elastic modulus of the lower chord steel structure. The parameters of the composite beam are obtained based on the relevant data and the preset acquisition formula. The parameters include: the bending stiffness of the composite beam, the internal force of the composite beam, the deformation of the composite beam, and the ultimate bearing capacity of the composite beam. The process of obtaining the flexural stiffness of the composite beam based on the relevant data and a preset formula includes: According to the preset formula for the bending stiffness of composite beams Obtain the flexural stiffness of the composite beam, where E c For the elastic modulus of the upper layer concrete, A c For the cross-sectional area of ​​the upper concrete layer, I c For the flexural stiffness of the upper concrete, E s For the elastic modulus of the lower chord steel structure, A s For the cross-sectional area of ​​the lower chord steel structure, I s The bending stiffness of the upper steel structure; according to E c I c Much larger than E s I s The formula for the bending stiffness of the composite beam is simplified to: ,in, The elastic modulus ratio of steel to concrete, This is the ratio of the cross-sectional area of ​​the lower chord steel structure to the cross-sectional area of ​​the upper concrete layer; If the composite beam structure is subjected to a concentrated load at mid-span, the process of obtaining the internal forces of the composite beam based on the relevant data and a preset formula includes: Obtain the centroidal bending moment of the bridge deck at the nth span of the composite beam. M c The bending moment of the concrete panel; N s This represents the total axial force of the lower chord steel structure. Will Substitution Obtain the axial force of the (n+1)th lower chord. Axial force of the nth lower chord of the steel structure Axial force of the diagonal web member at the nth internode Axial force of the vertical web member at the nth internode ; The shear force at the i-th end of the upper concrete layer of the n-th intersection is obtained based on the axial force of the (n+1)-th lower chord, the axial force of the n-th lower chord, the axial force of the diagonal web member at the n-th intersection, and the axial force of the vertical web member at the n-th intersection. Bending moment Axial force .

2. The method as described in claim 1, characterized in that, If the composite beam structure is subjected to uniformly distributed load, the process of obtaining the internal forces of the composite beam based on the relevant data and a preset formula includes: Obtain the axial force of the nth lower chord of the composite beam. Axial force of the diagonal web member at the nth internode Axial force of the vertical web member at the nth internode ; The shear force at the i-th end of the upper concrete layer of the n-th intersection is obtained based on the axial force of the n-th lower chord, the axial force of the diagonal web member at the n-th intersection, and the axial force of the vertical web member at the n-th intersection. Bending moment Axial force .

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