An assembled cold-formed C-shaped steel lateral support and an approximate design method thereof

Abstract

The application discloses a kind of cold bending C-shaped steel lateral support of assembly type and approximate design method, belong to building structure test equipment technical field, it is applicable to the out-of-plane bracing of truss structure, with high freedom, can be freely spliced according to the required size;Cold bending C-shaped steel lateral support is connected by support main structure, transverse connecting component, auxiliary support component and bottom fixing component;Support main structure includes two support main bodies, which is the left-right symmetrical structure of multilayer by a plurality of cold bending C-shaped steel triangular splicing components splicing, wherein cold bending C-shaped steel triangular splicing component is connected by three C-shaped section cold bending steel concave side punch inside sequentially, and is fixed by self-tapping screw at connecting end point;In the application, by designing cold bending C-shaped steel triangular splicing component and support main structure, stable lateral support can be provided for truss, and the accuracy of truss stress and the safety of test are ensured by support displacement checking in design method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building structure test equipment, and particularly relates to a fabricated cold-bent C-shaped steel lateral support and an approximate design method. BACKGROUND

[0002] In the mechanical test of the truss structure, the truss is prone to out-of-plane instability during the stress process, especially when the truss length is large and the lateral constraint is insufficient.

[0003] At present, the existing test room often lacks a specially designed lateral fixing device, for example, document 1: Chen Shaofan, Out-of-plane stability of compression web members of trusses and support system, Engineering Mechanics (01) (1996) 16-25, which leads to a decrease in test accuracy and may even cause the test to fail due to instability. In addition, for example, documents 2 and 3: Li Rui, Huang Zhenghua, Huang Yong, Parametric analysis of out-of-plane stability bearing capacity of plane steel pipe truss arch, Journal of Guizhou University (Natural Science Edition) 30 (04) (2013) 94-97, the stability bearing capacity of the structure is significantly increased after considering the lateral support; and document 4: Guo Yanlin, Dou Chao, Elastic stability performance and support stiffness design of I-shaped cross-section circular arc steel arch with out-of-plane support, Journal of Building Structures 33 (07) (2012) 37-45, when the lateral support stiffness meets the support threshold stiffness requirement, the lateral displacement of the section at the support point will be completely constrained when out-of-plane buckling occurs, ensuring the complete mechanical test of the truss structure.

[0004] Therefore, it is particularly important to develop a support that is stable in structure, easy to install and flexible to adjust. SUMMARY

[0005] The purpose of the present application is to solve the problem of out-of-plane instability in the existing truss test, provide a fabricated cold-bent C-shaped steel lateral support and an approximate design method, enhance the lateral stability of the support by designing a cold-bent C-shaped steel triangular splicing component and a support main structure, provide stable lateral support for the truss, effectively prevent the truss from producing out-of-plane instability during the stress test, and ensure the accuracy of the truss stress and the safety of the test through the support displacement calculation in the design method.

[0006] To achieve the above purpose, the following technical scheme is adopted in the present application: an approximate design method of a fabricated cold-bent C-shaped steel lateral support, comprising the following steps:

[0007] S1, a cold-bent C-shaped steel support system is constructed:

[0008] First, the concave sides of three C-shaped cross-section cold-bent steels are connected in sequence to form a cold-bent C-shaped steel triangular splicing component, and the connection end points are fixed by self-tapping screws;

[0009] The plurality of cold-bent C-shaped steel triangular splicing components are spliced to form two support bodies of a multi-layer left-right symmetrical structure, and the two support bodies are both large triangles with right-angle edges inward;

[0010] A C-shaped section cold-bent steel is fixedly connected to the inner side wall of the upper half of each of the two support bodies, and a tension bolt is connected between the two C-shaped section cold-bent steels;

[0011] A cold-bent C-shaped steel triangular splicing component with a right-angle edge inward is vertically fixed to the inner side front and rear end face of the lower half of each of the two support bodies, the cold-bent C-shaped steel triangular splicing component and the support body are fixedly connected through an L-shaped steel plate, and a tension bolt is further connected between the inner side walls of the lower half of the two support bodies;

[0012] S2, calculate the equivalent moment of inertia of the variable cross-section cantilever beam:

[0013] Based on the cold-bent C-shaped steel lateral support constructed above, for a rectangular cross-section, the moment of inertia

[0014] Divide the cross-section into four segments, and the upper equivalent moment of inertia is:

[0015] In the formula, I eq上 is the upper equivalent moment of inertia, b is the cross-sectional width, h is the length of the bottom edge, and I x is the moment of inertia of each segment;

[0016] For the lower trapezoidal support spliced by three cold-bent C-shaped steel triangular splicing components (7), the lower equivalent moment of inertia is:

[0017] In the formula, I eq下 is the lower equivalent moment of inertia;

[0018] After calculation, the final I eq下 ≈18I eq上 ;

[0019] S3, calculate the support displacement to determine whether it meets the limit value:

[0020] For an equal cross-section beam, the moment of inertia I is a constant, and the moment of inertia of the equal cross-section is converted into the moment of inertia of the variable cross-section, wherein for an equal cross-section cantilever component, the deflection calculation integral formula is:

[0021]

[0022] For a variable cross-section, the deflection calculation integral formula is:

[0023]

[0024] Suppose that the top of the support is subjected to a concentrated force P, according to the simplification in step S2, the displacement of the top of the support is:

[0025]

[0026] In the formula, H is the length of the longer vertical section of the cold-rolled C-shaped steel spliced triangular member (7) ; M p (x) and are the bending moments at the section height x of the variable cross-section column under the action of the actual and imaginary concentrated loads respectively; I(x) is the moment of inertia at the section height x, E is the elastic modulus of the material, Δ0 is the displacement of the support, Δ max is the maximum lateral displacement of the truss given by the tester;

[0027] To ensure the lateral resistance of the support, it is necessary to ensure that Δ0≤Δ max According to the truss test, the lateral force P that may occur is given by the tester, combined with the lateral displacement limit Δ max , so as to adjust the height / width of the cold-rolled C-shaped steel spliced triangular member or the section size of the corresponding C-shaped section cold-formed steel according to the calculation result;

[0028] In the step S3, the elastic modulus E of the C-shaped section cold-formed steel is 2.06 GPa, and the value of Δ max is taken

[0029] The application also discloses a fabricated cold-rolled C-shaped steel lateral support designed by the approximate design method.

[0030] The support body structure comprises two support bodies, and the two support bodies are both large triangles with inward right-angle edges, and are multi-layer left-right symmetrical structures composed of a plurality of cold-rolled C-shaped steel triangular spliced members.

[0031] The upper and lower inner side walls of the two support bodies are both provided with the transverse connecting members, and the transverse connecting members are tension bolts.

[0032] The inner front and rear end faces of the lower half of the two support bodies are both vertically fixed with an auxiliary support member, and the auxiliary support member is a cold-rolled C-shaped steel triangular spliced member with an inward right-angle edge.

[0033] Furthermore, a C-shaped cold-formed steel section with a concave side punch is fixedly connected to the inner side wall of the upper half of each of the two support bodies, and the two C-shaped cold-formed steel sections are connected to each other by tie bolts.

[0034] Furthermore, bolt holes are provided on both the C-shaped cold-formed steel and the L-shaped steel plate, and high-strength bolts are used to fix the support body and the interior of the cold-formed C-shaped steel triangular splice member, as well as the support body and the L-shaped steel plate, through the bolt holes.

[0035] The beneficial effects of this invention are:

[0036] 1) In this invention, the lateral stability of the support is enhanced by designing the cold-formed C-shaped steel triangular splice members and the main structure of the support. This provides stable lateral support for the truss, effectively preventing out-of-plane instability of the truss during the stress test. Furthermore, the support displacement verification in the design method ensures the accuracy of the truss stress and the safety of the test.

[0037] 2) In the support domain of the present invention, multiple cold-formed C-shaped steel triangular splicing members are connected by bolts to form a continuous support system, ensuring that the truss structure does not experience out-of-plane instability during the test; by inserting transverse connecting members between the cold-formed C-shaped steel triangular splicing members and by arranging auxiliary support members, the lateral stability of the support is enhanced, so that each part of the truss is stably fixed through the support system during the test.

[0038] 3) The support of the present invention adopts an assembled design, and all components are modular. On-site installation only requires bolt connection, without complicated welding operations, which greatly improves installation efficiency. The support height and connection position can be flexibly adjusted according to the truss test requirements, which is highly adaptable and can be applied to different test scenarios.

[0039] 4) The cold-formed C-shaped steel material used in this invention gives the support high strength and rigidity, while the design of the transverse connecting components and auxiliary support components greatly improves the stability of the overall structure; the standardized production and prefabricated design of cold-formed C-shaped steel reduces manufacturing and construction costs, and has good economic benefits. Attached Figure Description

[0040] Figure 1 This is a three-dimensional structural schematic diagram of the cold-formed C-shaped steel lateral support of the present invention;

[0041] Figure 2 for Figure 1 Structural schematic diagram of a triangular splicing member of a medium-cold-formed C-shaped steel structure;

[0042] Figure 3 for Figure 1 Schematic diagram of a C-shaped cold-formed steel section;

[0043] Figure 4 for Figure 1 A schematic diagram of the structure of the L-shaped steel plate.

[0044] In the figure, 1-support body, 2-C-section cold-formed steel, 3-bolt hole, 4-tie bolt, 5-L-shaped steel plate, 6-self-tapping screw, 7-cold-formed C-shaped steel triangular splicing component. Detailed Implementation

[0045] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments.

[0046] Example 1: As Figures 1 to 4 As shown, the present invention provides an assembled cold-formed C-shaped steel lateral support, which is composed of a support main structure, a transverse connecting component, an auxiliary support component, and a bottom fixing component. The support main structure includes two support bodies 1, and both support bodies 1 are large triangular structures with right-angled sides facing inward. The two support bodies 1 are two-layer left-right symmetrical structures formed by splicing multiple cold-formed C-shaped steel triangular splicing components 7.

[0047] The cold-formed C-shaped steel triangular splice component 7 is composed of three C-shaped cold-formed steel sections 2 connected sequentially on their concave sides, and the connection ends are fixed by self-tapping screws 6. Bolt holes 3 are provided on both the C-shaped cold-formed steel section 2 and the L-shaped steel plate 5. The support body 1 and the interior of the cold-formed C-shaped steel triangular splice component 7, as well as the support body 1 and the L-shaped steel plate 5, are all fixed by high-strength bolts through the bolt holes 3.

[0048] A transverse connecting member is connected between the upper and lower inner walls of the two support bodies 1, and the transverse connecting member is a tie bolt 4; a C-shaped cold-formed steel 2 with a concave side punch is fixedly connected to the inner wall of the upper half of the two support bodies 1, and the two C-shaped cold-formed steel 2 are connected to the tie bolt 4.

[0049] Each of the two support bodies 1 has an auxiliary support component vertically fixed on the inner front and rear end faces of the lower half. The auxiliary support component is a cold-formed C-shaped steel triangular splicing component 7 with its right-angled side facing inward. The cold-formed C-shaped steel triangular splicing component 7 is fixedly connected to the support body 1 through a bottom fastener, which is an L-shaped steel plate 5.

[0050] 1) Support main structure: Cold-formed C-shaped steel is used as the main support component. The components are connected by high-strength bolts, which have good load-bearing capacity and rigidity, and can provide stable support for the truss.

[0051] 2) Lateral connecting components: These are installed between the main bodies of the supports to connect the supports on the left and right sides into a whole, thereby enhancing the rigidity of the overall structure and preventing the supports from shifting laterally when under stress.

[0052] 3) Auxiliary support member: located on the side of the support body, using cold-bent C-shaped steel triangular splicing arrangement, by increasing the lateral support, improving the overall lateral force performance, to ensure that the support can work stably in the test.

[0053] 4) Bottom fixing member: the bottom of the support is designed with an L-shaped steel plate for connecting the support body and the auxiliary support member, which is connected by high-strength bolts to further enhance the stability of the support.

[0054] 5) Adjustable height design: the connection position of the main member and the auxiliary support member of the support can be adjusted, which can flexibly change the height of the support by adjusting the mounting hole position of the member, and adapt to different types and specifications of truss test requirements.

[0055] Example 2: The present application also provides an approximate design method of assembled cold-bent C-shaped steel lateral support, comprising the following steps:

[0056] S1, using cold-bent C-shaped steel to construct the support system:

[0057] As shown in Figure 1 , first connect three C-shaped section cold-bent steel 2 with concave side inward to form a cold-bent C-shaped steel triangular splicing member 7, and the connection end point is fixed by self-tapping screw 6;

[0058] A plurality of cold-bent C-shaped steel triangular splicing members 7 are spliced to form two support bodies 1 with multiple layers of left-right symmetrical structure, and both of the two support bodies 1 are large triangles with inner straight edges;

[0059] A piece of C-shaped section cold-bent steel 2 with concave side inward is fixedly connected to the inner side wall of the upper half of the two support bodies 1, and a tension bolt 4 is connected between the two C-shaped section cold-bent steels 2;

[0060] A cold-bent C-shaped steel triangular splicing member 7 with a straight edge inward is vertically fixed to the inner side of the lower half of the two support bodies 1, and the cold-bent C-shaped steel triangular splicing member 7 and the support body 1 are fixedly connected by an L-shaped steel plate 5, and a tension bolt 4 is also connected between the inner side walls of the lower halves of the two support bodies 1.

[0061] Take the length L of the truss specimen as 3000mm, the concentrated load P as 2kN, the cross-sectional size H of the designed cold-bent C-shaped steel splicing triangular member 7 as 400mm, h as 300mm, the cross-sectional width b of the corresponding C-shaped section cold-bent steel 2 as 100mm, the steel elastic modulus E as 2.06GPa, and Δ max not more than one thousandth of the length of the specimen.

[0062] S2, calculate the equivalent moment of inertia of the variable cross-section cantilever beam:

[0063] Based on the cold-formed C-shaped steel lateral support constructed above, for a rectangular section, its moment of inertia

[0064] The section is equally divided into 4 segments, and the upper equivalent moment of inertia is:

[0065] The lower equivalent moment of inertia is: I eq下 = 18I eq上 = 261818189.

[0066] S3, calculate the support displacement to judge whether it meets the limit value:

[0067] The concentrated load P = 2kN, and the displacement of the top of the support is:

[0068]

[0069] Therefore, the designed lateral support displacement meets the requirements of the truss test.

[0070] In the application, by designing the cold-formed C-shaped steel triangular splicing component and the support main body structure, the lateral stability of the support is enhanced, stable lateral support can be provided for the truss, out-of-plane instability of the truss in the stress test can be effectively prevented, and the support displacement in the design method is checked, so that the accuracy of the truss stress and the safety of the test are ensured.

[0071] The above description is only used to illustrate the technical solutions of the present application, not to limit it, and other modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art should be covered in the scope of the claims of the present application, as long as they do not deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. An approximate design method for prefabricated cold-formed C-shaped steel lateral supports, characterized in that: Includes the following steps: S1. The support system is constructed using cold-formed C-shaped steel. First, the concave sides of three C-shaped cold-formed steel sections (2) are connected in sequence to form a cold-formed C-shaped steel triangular splice component (7), and the connection ends are fixed by self-tapping screws (6); Multiple cold-formed C-shaped steel triangular splicing components (7) are spliced ​​together to form two support bodies (1) with a multi-layer left-right symmetrical structure, and both support bodies (1) are large triangular structures with right-angled sides facing inward; A C-shaped cold-formed steel section (2) with a concave side punch is fixedly connected to the inner wall of the upper half of the two support bodies (1), and a tie bolt (4) is connected between the two C-shaped cold-formed steel sections (2). A right-angled C-shaped steel triangular splicing component (7) with its right-angled side facing inward is vertically fixed on the inner front and rear end faces of the lower half of the two support bodies (1). The cold-formed C-shaped steel triangular splicing component (7) is fixedly connected to the support body (1) by an L-shaped steel plate (5), and tie bolts (4) are also connected between the inner walls of the lower half of the two support bodies (1). S2. Calculate the equivalent moment of inertia of the variable cross-section cantilever beam: Based on the lateral support for the cold-formed C-shaped steel constructed above, for a rectangular section, its moment of inertia... , Dividing the cross section into 4 equal segments, the equivalent moment of inertia of its upper part is: In the formula, The equivalent moment of inertia of the upper part, b For the cross-sectional width, h The length of the base is 1. The moment of inertia for each equally divided segment; For the trapezoidal support whose lower part is spliced ​​together by three cold-formed C-shaped steel triangular splicing members (7), its equivalent moment of inertia at the lower part is: In the formula, The equivalent moment of inertia for the lower part; The final result obtained after calculation ; S3. Calculate the support displacement and determine if it meets the limit: For a beam with a uniform cross-section, the moment of inertia I Since is a constant, the moment of inertia of a uniform cross-section is converted to the moment of inertia of a variable cross-section. For a cantilever member with a uniform cross-section, the integral formula for calculating its deflection is: ， For a variable cross section, the integral formula for calculating the deflection is: ， Assume a concentrated force is applied to the top of the support. P Based on the simplification in step S2, the displacement of the top of the support is: ， In the formula, H The length of the longer vertical segment of the cold-formed C-shaped steel spliced ​​triangular member (7); and The height of the variable cross-section column under real and hypothetical concentrated loads are respectively. x Bending moment at the point; Section height x Moment of inertia at that point, E The elastic modulus of the material, To support the seat shift, The maximum lateral displacement of the truss given by the tester; To ensure the lateral resistance of the support, it is necessary to ensure Based on the truss tests conducted, the testers shall provide the possible lateral forces. P Combined with outward displacement restriction Based on the calculation results, the height / width of the constructed cold-formed C-shaped steel splicing triangular member (7) or the cross-sectional dimensions of the corresponding C-shaped cold-formed steel (2) can be adjusted.

2. The approximate design method for a prefabricated cold-formed C-shaped steel lateral support according to claim 1, characterized in that: In step S3, the elastic modulus of the C-section cold-formed steel (2) is... E =2.06 GPa, The value takes .

Images