Fabricated cold-bending C-shaped steel lateral support and approximate design method

Abstract

The invention discloses a fabricated cold-bending C-shaped steel lateral support and an approximate design method, belongs to the technical field of building structure test equipment, is suitable for out-of-plane support of a truss structure, has high liberalization, and can be freely spliced according to the required size. The cold-bending C-shaped steel lateral support is formed by connecting a support body structure, a transverse connecting component, an auxiliary supporting component and a bottom fixing piece. The support body structure comprises two support bodies and is of a multi-layer left-right symmetrical structure formed by splicing a plurality of cold-bending C-shaped steel triangular splicing components, each cold-bending C-shaped steel triangular splicing component is formed by sequentially connecting the concave sides of three pieces of C-shaped section cold-bending steel in a punching mode, and the connecting end points are connected and fixed through self-tapping screws. According to the method, stable lateral support can be provided for the truss by designing the cold-bending C-shaped steel triangular splicing component and the support main body structure, and the stress accuracy of the truss and the test safety are ensured through support displacement checking calculation in the design method.

Description

Technical Field

[0001] The invention belongs to the technical field of building structure testing equipment, and in particular relates to an assembled cold-bent C-shaped steel lateral support and an approximate design method. Background Art

[0002] In the mechanical test of truss structure, the truss is prone to out-of-plane instability when subjected to force, especially when the truss is long and the lateral constraint is insufficient, this problem is particularly serious.

[0003] At present, there is often a lack of specially designed lateral fixing equipment in existing laboratories, such as Reference 1: Chen Shaofan, Out-of-plane stability and support system of truss compression web, Engineering Mechanics (01) (1996) 16-25, which will lead to reduced test accuracy and even failure of the test due to instability. In addition, for example, References 2 and 3: Li Rui, Huang Zhenghua, Huang Yong, Parametric analysis of out-of-plane stability bearing capacity of plane steel tube truss arch, Journal of Guizhou University (Natural Science Edition) 30 (04) (2013) 94-97, after considering lateral support, the stability bearing capacity of the structure is significantly increased; and Reference 4: Guo Yanlin, Dou Chao, Elastic stability performance and support stiffness design of I-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 requirements, the lateral displacement of the section at the support point will be fully constrained when out-of-plane buckling occurs, ensuring that the mechanical test of the truss structure is carried out completely.

[0004] Therefore, it is particularly important to develop a support that is structurally stable, easy to install and flexibly adjustable. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of out-of-plane instability in existing truss tests, and to provide an assembled cold-bent C-shaped steel lateral support and an approximate design method. By designing cold-bent C-shaped steel triangular splicing components and a support main structure, the lateral stability of the support is enhanced, and stable lateral support can be provided for the truss. The out-of-plane instability of the truss can be effectively prevented during a stress test, and the accuracy of the truss stress and the safety of the test can be ensured through the support displacement verification in the design method.

[0006] To achieve the above object, the present invention adopts the following technical solution: an approximate design method for an assembled cold-formed C-shaped steel lateral support, comprising the following steps:

[0007] S1. Use cold-bent C-shaped steel to construct the support system:

[0008] First, the concave side punches of three C-section cold-formed steels are connected in sequence to form a cold-formed C-section steel triangular splicing component, and the connection ends are fixed by self-tapping screws;

[0009] A plurality of cold-formed C-shaped steel triangular splicing components are spliced ​​together to form two support bodies of a multi-layer bilaterally symmetrical structure, and both support bodies are large triangular structures with right-angle sides facing inwards;

[0010] A piece of C-section cold-formed steel in a concave side punch is fixedly connected to the inner side wall of the upper half of the two support bodies, and tension bolts are connected between the two C-section cold-formed steels;

[0011] A cold-bent C-shaped steel triangular splicing member with a right-angle side facing inward is vertically fixed on the inner front and rear end surfaces of the lower halves of the two support bodies. The cold-bent C-shaped steel triangular splicing member is fixedly connected to the support body through an L-shaped steel plate, and tension bolts are also connected between the inner side walls of the lower halves of the two support bodies.

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

[0013] Based on the above-mentioned cold-formed C-shaped steel lateral support, for a rectangular section, its moment of inertia is

[0014] The cross section is divided into 4 equal sections, and the equivalent moment of inertia of the upper section is:

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

[0016] For a trapezoidal support whose lower part is composed of three cold-formed C-shaped steel triangular splicing members (7), the equivalent moment of inertia of the lower part is:

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

[0018] After calculation, we finally get I eq下 ≈18I eq上 ;

[0019] S3. Calculate the displacement of the bearing to determine whether it meets the limit value:

[0020] For a beam with a uniform cross-section, the moment of inertia I is a constant. The moment of inertia of a uniform cross-section is converted into the moment of inertia of a variable cross-section. For a cantilever member with a uniform cross-section, the integral formula for calculating the deflection is:

[0021]

[0022] For variable cross-sections, the integral formula for calculating deflection is:

[0023]

[0024] Assuming 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] Where H is the length of the longer vertical section of the cold-formed C-shaped steel triangular member (7); M p (x) and are the bending moments at the height x of the variable cross-section column under real and imaginary concentrated loads, respectively; I(x) is the moment of inertia at the height x of the section, E is the elastic modulus of the material, Δ0 is the support displacement, Δ max is the maximum lateral displacement of the truss given by the tester;

[0027] To ensure the lateral resistance of the bearing, it is necessary to ensure that Δ0≤Δ max ; According to the truss test conducted, the tester gives the possible lateral force P and the outer lateral displacement limit Δ max , so as to adjust the height / width of the constructed cold-formed C-shaped steel spliced ​​triangular member or the cross-sectional size of the corresponding C-section cold-formed steel according to the calculation results;

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

[0029] The present invention also discloses an assembled cold-bent C-shaped steel lateral support designed by the above-mentioned approximate design method, wherein the cold-bent C-shaped steel lateral support is composed of a support main structure, a transverse connecting member, an auxiliary supporting member and a bottom fixing member;

[0030] The support main body structure includes two support bodies, and both support bodies are large triangular structures with right-angled sides facing inwards. The two support bodies are multi-layer left-right symmetrical structures formed by splicing a plurality of cold-bent C-shaped steel triangular splicing components, wherein the cold-bent C-shaped steel triangular splicing components are composed of three C-section cold-bent steel concave side punches connected in sequence, and the connection end points are connected and fixed by self-tapping screws;

[0031] The transverse connecting member is arranged between the upper and lower inner side walls of the two support bodies, and the transverse connecting member adopts tension bolts;

[0032] An auxiliary support member is vertically fixed on the inner front and rear end surfaces of the lower halves of the two support bodies. The auxiliary support member is a cold-bent C-shaped steel triangular splicing member with right-angled sides facing inward. The cold-bent C-shaped steel triangular splicing member is fixedly connected to the support body by a bottom fixing piece, and the bottom fixing piece is an L-shaped steel plate.

[0033] Furthermore, a piece of C-section cold-bent steel in a concave side punch is fixedly connected to the inner side walls of the upper halves of the two support bodies, and the two C-section cold-bent steels are connected with tension bolts.

[0034] Furthermore, bolt holes are provided on the C-section cold-bent steel and the L-shaped steel plate, and the support body and the inside of the cold-bent C-shaped steel triangular splicing component and the support body and the L-shaped steel plate are fixed by connecting high-strength bolts through the bolt holes.

[0035] The beneficial effects of the present invention are:

[0036] 1) In the present invention, the lateral stability of the support is enhanced by designing the cold-bent C-shaped steel triangular splicing components and the support main structure, which can provide stable lateral support for the truss, effectively prevent the truss from producing out-of-plane instability during the stress test, and through the support displacement verification in the design method, the accuracy of the truss stress and the safety of the test are ensured.

[0037] 2) In the support domain of the present invention, multiple cold-bent C-shaped steel triangular spliced ​​components are connected by bolts to form a continuous support system, ensuring that the truss structure does not suffer from out-of-plane instability during the test; by inserting transverse connecting members between the cold-bent C-shaped steel triangular spliced ​​components and 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 the need for complex welding operations, which greatly improves installation efficiency; the support height and connection position can be flexibly adjusted according to the requirements of the truss test, with strong adaptability and can be applied to different experimental scenarios.

[0039] 4) The cold-bent C-shaped steel material used in the present invention gives the support higher strength and rigidity, while the design of the transverse connecting members and auxiliary supporting members greatly improves the stability of the overall structure; the standardized production and assembled design of the cold-bent C-shaped steel reduce the manufacturing and construction costs and have good economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the three-dimensional structure of the cold-bent C-shaped steel lateral support of the present invention;

[0041] Figure 2 for Figure 1 Schematic diagram of the structure of the cold-bent C-shaped steel triangular spliced ​​components;

[0042] Figure 3 for Figure 1 Schematic diagram of the structure of medium C-section cold-formed steel;

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

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

[0045] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

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

[0047] The cold-bent C-shaped steel triangular splicing component 7 is composed of three C-section cold-bent steels 2 connected in sequence with their concave side punches, and the connection end points are connected and fixed by self-tapping screws 6; bolt holes 3 are provided on the C-section cold-bent steel 2 and the L-shaped steel plate 5, and the support body 1 and the cold-bent C-shaped steel triangular splicing component 7 and the support body 1 and the L-shaped steel plate 5 are connected and fixed with 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 adopts tension bolts 4; a C-section cold-bent 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-section cold-bent steels 2 are connected with tension bolts 4.

[0049] An auxiliary support member is vertically fixed on the inner front and rear end surfaces of the lower halves of the two support bodies 1. The auxiliary support member is a cold-bent C-shaped steel triangular splicing member 7 with a right-angled side facing inward. The cold-bent C-shaped steel triangular splicing member 7 is fixedly connected to the support body 1 through a bottom fixing member, and the bottom fixing member is an L-shaped steel plate 5.

[0050] 1) Support main structure: Cold-bent C-shaped steel is used as the main supporting member. The members are connected by high-strength bolts. It has good bearing capacity and rigidity and can provide stable support for the truss.

[0051] 2) Transverse connecting member: It is set between the support bodies and is used to connect the supports on the left and right sides into one, thereby enhancing the rigidity of the overall structure and preventing the supports from producing lateral displacement when subjected to force.

[0052] 3) Auxiliary support member: Located on the side of the support body, it adopts a cold-bent C-shaped steel triangle splicing layout. By increasing lateral support, the overall lateral force resistance performance is improved to ensure that the support can work stably during the test.

[0053] 4) Bottom fixings: An L-shaped steel plate is designed at the bottom of the support to connect the support body and the auxiliary supporting 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 components and auxiliary support components of the support is adjustable. The height of the support can be flexibly changed by adjusting the installation hole position of the components to meet the test requirements of trusses of different types and specifications.

[0055] Embodiment 2: The present invention also provides an approximate design method for an assembled cold-formed C-shaped steel lateral support, comprising the following steps:

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

[0057] like Figure 1 As shown, first, the concave side punches of three C-section cold-bent steels 2 are sequentially connected to form a cold-bent C-shaped steel triangular splicing member 7, and the connection end points are fixed by self-tapping screws 6;

[0058] A plurality of cold-bent C-shaped steel triangular splicing components 7 are spliced ​​together to form two support bodies 1 of a multi-layer bilaterally symmetrical structure, and both support bodies 1 are large triangular structures with right-angle sides facing inwards;

[0059] A piece of C-section cold-formed steel 2 in a concave side punch 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-section cold-formed steels 2;

[0060] A cold-bent C-shaped steel triangular splicing component 7 with its right-angled sides facing inward is vertically fixed to the inner front and rear end surfaces of the lower halves of the two support bodies 1. The cold-bent C-shaped steel triangular splicing component 7 is fixedly connected to the support body 1 via an L-shaped steel plate 5, and tension bolts 4 are also connected between the inner side walls of the lower halves of the two support bodies 1.

[0061] Take the truss specimen length L = 3000mm, concentrated load P = 2kN, design the cross-sectional dimensions of the basic cold-bent C-shaped steel spliced ​​triangular member 7 H = 400mm, h = 300mm, the cross-sectional width of the corresponding C-shaped cold-bent steel 2 b = 100mm, the steel elastic modulus E = 2.06GPa, Δ max Not exceeding 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 above-mentioned cold-formed C-shaped steel lateral support, for a rectangular section, its moment of inertia is

[0064] The cross section is divided into 4 equal sections, and the equivalent moment of inertia of the upper section is:

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

[0066] S3. Calculate the displacement of the bearing to determine whether it meets the limit value:

[0067] Concentrated load P = 2kN, it can be seen that the displacement of the top of the support is:

[0068]

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

[0070] In the present invention, the lateral stability of the support is enhanced by designing cold-bent C-steel triangular splicing components and the support main structure, which can provide stable lateral support for the truss, effectively prevent the truss from producing out-of-plane instability during the stress test, and through the support displacement verification in the design method, 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 solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. An approximate design method for assembled cold-formed C-shaped steel lateral supports, characterized in that: The following steps are involved: S1. Use cold-bent C-shaped steel to construct the support system: First, the concave side punches of three C-section cold-bent steels (2) are connected in sequence to form a cold-bent C-section steel triangular splicing component (7), and the connection end points are fixed by self-tapping screws (6); A plurality of cold-bent C-shaped steel triangular splicing components (7) are spliced ​​together to form two support bodies (1) of a multi-layer bilaterally symmetrical structure, wherein both support bodies (1) are large triangular structures with right-angled sides facing inwards; A piece of C-section cold-bent steel (2) in a concave side punch 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-section cold-bent steels (2); A cold-bent C-shaped steel triangular splicing component (7) with a right-angle side facing inward is vertically fixed to the front and rear end surfaces on the inner sides of the lower halves of the two support bodies (1); the cold-bent C-shaped steel triangular splicing component (7) and the support body (1) are fixedly connected via an L-shaped steel plate (5); and tension bolts (4) are also connected between the inner side walls of the lower halves of the two support bodies (1); S2. Calculate the equivalent moment of inertia of the variable cross-section cantilever beam: Based on the above-mentioned cold-formed C-shaped steel lateral support, for a rectangular section, its moment of inertia is The cross section is divided into 4 equal sections, and the equivalent moment of inertia of the upper section is: In the formula, I eq上 is the equivalent moment of inertia of the upper part, b is the cross-sectional width, h is the length of the bottom side, I x is the moment of inertia of each equally divided segment; For a trapezoidal support whose lower part is composed of three cold-formed C-shaped steel triangular splicing members (7), the equivalent moment of inertia of the lower part is: In the formula, I eq下 is the equivalent moment of inertia of the lower part; After calculation, we finally get I eq下 ≈18I eq上 ; S3. Calculate the displacement of the bearing to determine whether it meets the limit value: For a beam with a uniform cross-section, the moment of inertia I is a constant. The moment of inertia of a uniform cross-section is converted into the moment of inertia of a variable cross-section. For a cantilever member with a uniform cross-section, the integral formula for calculating the deflection is: For variable cross-sections, the integral formula for calculating deflection is: Assuming 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: Where H is the length of the longer vertical section of the cold-formed C-shaped steel triangular member (7); M p (x) and are the bending moments at the height x of the variable cross-section column under real and imaginary concentrated loads, respectively; I(x) is the moment of inertia at the height x of the section, E is the elastic modulus of the material, Δ0 is the support displacement, Δ max is the maximum lateral displacement of the truss given by the tester; To ensure the lateral resistance of the bearing, it is necessary to ensure that Δ0≤Δ max ; According to the truss test conducted, the tester gives the possible lateral force P and the outer lateral displacement limit Δ max , thereby adjusting the height / width of the constructed cold-bent C-shaped steel spliced ​​triangular member (7) or the cross-sectional dimensions of the corresponding C-section cold-bent steel (2) according to the calculation results.

2. The assembled cold-formed C-shaped steel lateral support and the approximate design method according to claim 1, characterized in that: In the step S3, the elastic modulus of the C-section cold-bent steel (2) is E=2.06 GPa, Δ max The value of 3. An assembled cold-formed C-shaped steel lateral support designed by the approximate design method described in any one of claims 1 to 2, characterized in that: The cold-bent C-shaped steel lateral support is composed of a support main structure, a transverse connecting member, an auxiliary supporting member and a bottom fixing member; The support main body structure comprises two support bodies (1), and both support bodies (1) are large triangular structures with right-angled sides facing inwards. The two support bodies (1) are multi-layer bilaterally symmetrical structures formed by splicing a plurality of cold-bent C-shaped steel triangular splicing components (7), wherein the cold-bent C-shaped steel triangular splicing components (7) are composed of three C-shaped cross-section cold-bent steels (2) connected in sequence by concave side punches, and the connection end points are connected and fixed by self-tapping screws (6); The transverse connecting member is provided between the upper and lower inner side walls of the two support bodies (1), and the transverse connecting member adopts tension bolts (4); An auxiliary support member is vertically fixed to the front and rear end surfaces on the inner sides of the lower halves of the two support bodies (1); the auxiliary support member is a cold-bent C-shaped steel triangular splicing member (7) with right-angled sides facing inwards; the cold-bent C-shaped steel triangular splicing member (7) is fixedly connected to the support body (1) via a bottom fixing member, and the bottom fixing member is an L-shaped steel plate (5).

4. The assembled cold-formed C-shaped steel lateral support according to claim 3 is characterized in that: A piece of C-section cold-bent steel (2) in a concave side punch is fixedly connected to the inner side walls of the upper halves of the two support bodies (1), and the two C-section cold-bent steels (2) are connected with tension bolts (4).

5. The assembled cold-formed C-shaped steel lateral support according to claim 3 is characterized in that: The C-section cold-bent steel (2) and the L-shaped steel plate (5) are both provided with bolt holes (3), and the support body (1) and the inside of the cold-bent C-section steel triangular splicing component (7) as well as the support body (1) and the L-shaped steel plate (5) are connected and fixed by high-strength bolts through the bolt holes (3).

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