Method for determining normal section bending moment of adapter ring of steel-concrete hybrid wind power tower drum under axial pressure working condition

Abstract

The embodiment of the invention discloses a method for determining the normal section bending moment of an adapter ring of a steel-concrete hybrid wind power tower drum under an axial pressure working condition. The method comprises the following steps: acquiring a preset axial pressure on the adapter ring, a preset prestress generated by a prestressed tendon and a geometric dimension of the adapter ring; according to a preset stress equivalent conversion scheme, the adapter ring of any arc angle in the adapter rings is taken as an isolator for stress analysis, and target parameters are obtained through simplified calculation based on the axial pressure, the prestress and the geometric dimension; and obtaining the normal section bending moment of the adapter ring through a pre-established normal section bending moment formula according to the target parameter. According to the invention, the blank of the existing design specification is filled; through theoretical derivation and finite element verification, the reliability of a calculation result is ensured; and a scientific basis is provided for optimization design and safety evaluation of the adapter ring, and the engineering risk is reduced.

Description

Technical Field

[0001] This invention relates to the field of wind power tower structure design, specifically to a method for determining the bending moment of the positive section of a steel-concrete hybrid wind power tower transition ring under axial compression conditions. Background Technology

[0002] With the rapid development of wind power generation technology, steel-concrete composite towers are widely used due to their excellent mechanical properties and economic benefits. The transition ring, as a key component connecting the upper steel tower and the lower concrete tower, experiences complex stresses, but currently lacks specific design specifications. Traditional design methods often employ simplified models or empirical formulas, leading to significant deviations between calculated results and actual stress states, potentially causing structural safety hazards. Therefore, an accurate method for calculating the bending moment of the transition ring's cross-section is urgently needed to improve the reliability and economy of structural design. Summary of the Invention

[0003] To address the technical problems mentioned in the background section, this invention proposes a method for determining the bending moment of the transition ring of a steel-concrete hybrid wind turbine tower under axial compression conditions. This method accurately calculates the bending moment distribution of the transition ring under complex loads, providing a theoretical basis for structural design and reinforcement.

[0004] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:

[0005] A method for determining the bending moment of the cross-section of a steel-concrete hybrid wind turbine tower transition ring under axial compression conditions, the method comprising:

[0006] Obtain the preset axial pressure on the adapter ring, the preset prestress generated by the prestressing tendons, and the geometric dimensions of the adapter ring;

[0007] Based on the preset force equivalent transformation scheme, the transition ring at any arc angle in the transition ring is taken as the isolation body for force analysis. Based on the axial pressure, the prestress, and the geometric dimensions, the target parameters are obtained through simplified calculation. The target parameters include:

[0008] The concentrated force F generated by the prestressing tendons in the isolation body pt And the distance L1 from the equivalent point of force application to the axis of the transition ring;

[0009] Concentrated force caused by axial pressure in the isolation body And the distance L2 from the equivalent point of force application to the axis of the transition ring;

[0010] The distance L0 from the equivalent stress point of the uniformly distributed stress in the isolator to the axis of the transition ring;

[0011] Based on the target parameters and using a pre-established formula for the normal section bending moment, the normal section bending moment of the transition ring is obtained. as follows:

[0012] ;

[0013] In the formula, α represents half of the arc angle.

[0014] In an optional embodiment, the geometry includes the outer radius R of the bottom cross-section of the adapter ring. ab and the inner radius r of the bottom cross section of the adapter ring ab The force equivalent transformation scheme includes:

[0015] The axial pressure G is converted into an axial pressure line load q distributed along the top cross section of the transition ring. G ,have:

[0016] ;

[0017] In the formula, L G For q G The radius of the area of ​​effect;

[0018] The prestress P is converted into a prestressed line load q distributed along the top section of the transition ring. pt ,have:

[0019] ;

[0020] In the formula, L pt For q pt The radius of the area of ​​action, where n is the number of prestressing tendons;

[0021] The axial pressure G and n P acting on the bottom of the transition ring are converted into a uniformly distributed stress at the bottom of the transition ring. ,have:

[0022] .

[0023] In an optional implementation, the force analysis includes the following force conditions:

[0024] The prestressed linear load q pt The equivalent line load generated by the prestressed tendons that are uniformly distributed on the top section of the isolator;

[0025] The axial pressure line load q G The equivalent line load is caused by the axial pressure uniformly distributed on the top section of the isolator;

[0026] The uniformly distributed stress As a surface load uniformly distributed on the bottom section of the isolator.

[0027] In an optional implementation, the axial pressure is simplified using the following formula, based on q. G Calculate concentrated force :

[0028] .

[0029] In an optional implementation, the prestressing is simplified using the following formula, based on q. pt Calculate concentrated force F pt :

[0030] .

[0031] In an optional implementation, according to L pt Calculate L1 using the following formula:

[0032] .

[0033] In an optional implementation, according to L G Calculate L2 using the following formula:

[0034] .

[0035] In an optional implementation, according to R ab and r a Calculate L0 using the following formula:

[0036] .

[0037] The embodiments of this application have the following beneficial effects:

[0038] This application discloses a method for determining the bending moment of the cross-section of a steel-concrete hybrid wind turbine tower transition ring under axial compression. The method involves obtaining a preset axial pressure on the transition ring, a preset prestress generated by prestressing tendons, and the geometric dimensions of the transition ring. Based on a preset force equivalent transformation scheme, the transition ring at any arc angle is taken as an isolator for force analysis. Based on the axial pressure, prestress, and geometric dimensions, target parameters are obtained through simplified calculations. These target parameters include the concentrated force F generated by the prestressing tendons in the isolator. pt And the distance L1 from the equivalent point of application of the concentrated force to the axis of the transition ring; the concentrated force caused by the axial pressure in the isolator. And the distance L2 from the equivalent point of application of the concentrated force to the axis of the transition ring; the distance L0 from the equivalent point of application of the uniformly distributed stress in the isolation body to the axis of the transition ring; based on the target parameters and the pre-established formula for the normal section bending moment, the normal section bending moment of the transition ring is obtained. This application not only fills a gap in existing design specifications and ensures the reliability of calculation results through theoretical derivation and finite element verification, but also provides a scientific basis for the optimized design and safety assessment of transition rings, reducing engineering risks. Attached Figure Description

[0039] To more clearly illustrate the technical solution of the present invention, the accompanying drawings required in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and therefore should not be regarded as a limitation on the scope of protection of the present invention. In the various drawings, similar components are numbered similarly.

[0040] Figure 1 A schematic diagram of a method proposed in an embodiment of this application is shown;

[0041] Figure 1 This illustration shows the location of the steel-concrete hybrid tower transition ring on the tower according to an embodiment of this application;

[0042] Figure 2 A simplified model diagram of the adapter ring under axial compression according to an embodiment of this application is shown.

[0043] Figure 3 A schematic diagram of the steel-concrete hybrid tower transition ring structure according to an embodiment of this application is shown;

[0044] Figure 4 A partial force diagram of the adapter ring according to an embodiment of this application is shown;

[0045] Figure 5 A schematic diagram of the various radii of the adapter ring according to an embodiment of this application is shown;

[0046] Figure 6 A schematic diagram of the adapter ring isolator and its load distribution according to an embodiment of this application is shown;

[0047] Figure 7 A schematic diagram of the scheme for converting the load on the adapter ring isolator into a concentrated force according to an embodiment of this application is shown. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0049] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the specific loads and dimensions described below may be arbitrarily changed and are only used to complement the content disclosed in the specification for those skilled in the art to understand and read. They are not intended to limit the implementation conditions of the present invention and therefore have no substantial technical significance. Any modifications to the methods and parameters, changes to the loads, or adjustments to the dimensions, without affecting the effects and objectives that the present invention can produce, still fall within the scope of the technical content disclosed in the present invention.

[0050] To more clearly demonstrate the implementation steps and advantages of this invention, the specific implementation methods are described below with reference to the illustrations.

[0051] This application proposes a method for determining the bending moment of the cross-section of a steel-concrete hybrid wind turbine tower transition ring under axial compression conditions. This method fills a gap in existing design specifications, ensures the reliability of calculation results, and provides a scientific basis for the optimized design and safety assessment of the transition ring, thereby reducing engineering risks. The specific implementation steps of this method are illustrated below:

[0052] By obtaining the preset axial pressure on the transition ring, the preset prestress generated by the prestressing tendons, and the geometric dimensions of the transition ring;

[0053] Based on the preset force equivalent transformation scheme, the transition ring at any arc angle in the transition ring is taken as the isolation body for force analysis. Based on axial pressure, prestress, and geometric dimensions, the target parameters are obtained through simplified calculation. The target parameters include:

[0054] Concentrated force F generated by prestressing tendons in the isolated body pt And the distance L1 from the equivalent point of force application to the axis of the transition ring;

[0055] Concentrated force caused by axial pressure in the isolation body And the distance L2 from the equivalent point of force application to the axis of the transition ring;

[0056] The distance L0 from the equivalent stress point of uniform stress distribution in the isolator to the axis of the transition ring;

[0057] Based on the target parameters and using the pre-established formula for the normal section bending moment, the normal section bending moment of the transition ring is obtained. :

[0058] ;

[0059] In the formula, M x F represents the bending moment at the normal section. pt This indicates the concentrated force generated by the prestressing tendons. L1 represents the concentrated force caused by axial pressure. pt The distance from the equivalent point of force application to the center of the adapter ring, L2 represents F. G The distance from the equivalent stress point to the axis of the transition ring is L0, where L0 represents the distance from the equivalent stress point to the axis of the transition ring, and α represents half of the arc angle.

[0060] Specifically, such as Figure 1 As shown, the steel-concrete hybrid wind turbine tower includes a steel tower, a wind turbine, a transition ring, and a concrete tower. The steel tower is connected to the transition ring via a flange. The position of the transition ring on the steel-concrete hybrid wind turbine tower is as follows. Figure 1 As shown.

[0061] Under axial compression conditions, the load borne by the transition ring in this application is simplified into two parts, by Figure 2 It is known that the load includes: the axial pressure G composed of the wind turbine gravity load G1 and the self-weight G2 of the steel tower section, and the prestress P generated by the prestressing tendons. Among these, the axial pressure G, the prestress P generated by the prestressing tendons, and the prestress nP generated by n prestressing tendons are all determined according to design requirements, i.e., they are all pre-set. The structure of the transition ring in this application is as follows: Figure 3 As shown, its geometric dimensions can be determined by pre-design or obtained based on actual measurements. The geometric dimensions of the adapter ring include the outer radius R of the bottom cross-section of the adapter ring. ab The inner radius r of the bottom section of the adapter ring ab The outer radius R of the top section of the adapter ring at and the inner radius r of the top section of the adapter ring at By obtaining the preset axial pressure G, the prestress P generated by the prestressing tendons, and the geometric dimensions of the transition ring, the bending moment M of the normal section can be calculated. x It is then used for subsequent reinforcement. In practice, the bending moment of the transition structure can be calculated based on the pre-designed load of the transition ring and the measured geometric dimensions.

[0062] This scheme will calculate the bending moment of the steel-concrete hybrid wind turbine tower transition ring under axial compression under the following assumptions. The four stress assumptions include: assuming that the top and bottom sections of the transition ring conform to the plane section assumption; assuming that the transition ring is under full-section compression, ignoring the effects of interface opening and bottom friction; and assuming that the resultant shear stress of the section is applied at the centroid of the cross-section.

[0063] In addition, the local stress diagram of the adapter ring is as follows: Figure 4 As shown, the top section of the transition ring is subjected to axial pressure G and prestress P generated by the prestressing tendons. This scheme proposes an equivalent force transformation method, including converting the aforementioned axial pressure G into an axial pressure line load q distributed along the top section of the transition ring. G ,have: L G For q G The radius of the effective area can be obtained through measurement; the prestress P is converted into a prestressed line load q distributed along the top section of the transition ring. pt ,have: L pt For q pt The radius of the effective area can be obtained through measurement, and n is the number of prestressing tendons; the axial pressure G acting on the bottom of the transition ring and the prestress P generated by the n prestressing tendons are transformed into a uniformly distributed stress at the bottom of the transition ring. ,have: .like Figure 5 As shown, R ab The outer radius r of the bottom section of the adapter ring is indicated by the number of radii. ab This indicates the inner radius of the bottom cross section of the adapter ring.

[0064] In the theoretical derivation process, such as Figure 6 As shown, we analyze a freestanding body with an arc angle of 2α and a height of H. The main forces acting on the freestanding body are as follows: axial pressure line load q pt The equivalent line load q generated by the prestressing tendons uniformly distributed at the top section of the isolated body pt ; axial pressure line load q G The equivalent line load q caused by the axial pressure uniformly distributed at the top section of the isolated body G The uniformly distributed stress σ R The surface load σ is uniformly distributed at the bottom section of the isolated body. R (ρ,θ), radial coordinate ρ, angle θ; the required bending moment Mx acting on the lateral section of the isolated body; the vertical shear force F acting on the lateral section of the isolated body. s .

[0065] Among them, such as Figure 7The diagram illustrates the conversion of the load on the isolator of the transition ring into a concentrated force. The load on the isolator is transformed into a corresponding concentrated force. Using a pre-defined simplified formula for axial pressure, the equivalent line load q generated by the axial pressure at the top section of the isolator is calculated. G Calculate the concentrated force F generated by the axial pressure in the isolated body. G The simplified formula for axial pressure is:

[0066]

[0067] Using a pre-defined simplified prestressing formula, the equivalent line load q caused by the prestressing tendons at the top section of the isolator is calculated. pt Calculate the concentrated force F generated by the prestressing tendons pt The simplified formula for prestressing is:

[0068]

[0069] Vertical shear force F s Calculated by the following formula:

[0070]

[0071] Concentrated force F generated by prestressing tendons pt The distance L1 from the equivalent point of force application to the center of the adapter ring is calculated using the following formula:

[0072]

[0073] Concentrated force F caused by axial pressure G The distance L2 from the equivalent point of force application to the center of the adapter ring is calculated using the following formula:

[0074]

[0075] Uniformly distributed stress in the isolation body Simplified to stress concentration force F R The distance L0 from the equivalent stress point of uniformly distributed stress to the axis of the transition ring is determined by R. ab and r a The formula for calculating L0 is as follows:

[0076]

[0077] After obtaining the above target parameters, the normal section bending moment M is calculated using the preset normal section bending moment formula. x .

[0078] In the specific implementation process, the values ​​of axial pressure G and prestress P will first be determined based on the actual engineering parameters. Then, the geometric dimensions of the transition ring will be determined by measurement or design, including the inner and outer radii and height of the top and bottom sections, the anchorage positions of the prestressing tendons and bolts, etc. The bending moment of the normal section will be calculated using a preset bending moment calculation formula. Substituting the load and geometric parameters into the formula, the bending moment value M of each section of the transition ring will be calculated. x .

[0079] This application uses a specific engineering project as an example, with load parameters G=3490 kN, M=13600 kN⋅m, nP=29070 kN; and geometric parameters R. ab =2500mm, r ab =2200mm, R at =2270mm, r at =1490mm, L G =1880mm, L pt =1780mm, H=2300mm, H 裙 =300mm, substituting these parameters into the formula, the maximum bending moment of the cross section is calculated to be 2964.44kN·m. Comparing the calculated maximum bending moment of the cross section with the corresponding finite element simulation results, the error is 3.17%, which meets the engineering accuracy requirements.

[0080] Furthermore, based on this engineering embodiment, with L G L pt Ten control groups (CG1-CG10) were set with parameters such as adapter ring thickness, diameter-to-thickness ratio, and adapter ring taper. The corresponding dimensional data are shown in Table 1 below.

[0081]

[0082] Table 1

[0083] The data in Table 2 below can be obtained by calculating the bending moment of the normal section using the formula of this application and by finite element simulation:

[0084]

[0085] Table 2

[0086] In the table above, the units for "M-theoretical" and "M-simulation" are both kN.m. After comparing multiple sets of finite element simulations with theoretical calculations, it can be found that the units for all groups of M... x The errors are all within the range of (2.42, 3.79%), therefore, this formula for the bending moment of the normal section can be considered valid.

[0087] In summary, this application provides a high-precision method for determining the bending moment of the normal section of a transition ring, which not only fills the gap in existing design specifications; but also ensures the reliability of the calculation results through theoretical derivation and finite element verification; and provides a scientific basis for the optimized design and safety assessment of transition rings, thereby reducing engineering risks.

[0088] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the bending moment of the cross-section of a steel-concrete hybrid wind turbine tower transition ring under axial compression conditions, characterized in that, The method includes: Obtain the preset axial pressure on the adapter ring, the preset prestress generated by the prestressing tendons, and the geometric dimensions of the adapter ring; Based on the preset force equivalent transformation scheme, the transition ring at any arc angle in the transition ring is taken as the isolation body for force analysis. Based on the axial pressure, the prestress, and the geometric dimensions, the target parameters are obtained through simplified calculation. The target parameters include: The concentrated force F generated by the prestressing tendons in the isolation body pt And the distance L1 from the equivalent point of force application to the axis of the transition ring; Concentrated force caused by axial pressure in the isolation body And the distance L2 from the equivalent point of force application to the axis of the transition ring; The distance L0 from the equivalent stress point of the uniformly distributed stress in the isolator to the axis of the transition ring; Based on the target parameters and using a pre-established formula for the normal section bending moment, the normal section bending moment of the transition ring is obtained. as follows: ； In the formula, α represents half of the arc angle.

2. The method for determining the bending moment of a cross section according to claim 1, characterized in that, The geometric dimensions include the outer radius R of the bottom cross section of the adapter ring. ab and the inner radius r of the bottom cross section of the adapter ring ab The force equivalent transformation scheme includes: The axial pressure G is converted into an axial pressure line load q distributed along the top cross section of the transition ring. G ,have: ； In the formula, L G For q G The radius of the area of ​​effect; The prestress P is converted into a prestressed line load q distributed along the top section of the transition ring. pt ,have: ； In the formula, L pt For q pt The radius of the area of ​​action, where n is the number of prestressing tendons; The axial pressure G and n P acting on the bottom of the transition ring are converted into a uniformly distributed stress at the bottom of the transition ring. ,have: 。 3. The method for determining the bending moment of a cross section according to claim 2, characterized in that, The force analysis includes the following force conditions: The prestressed linear load q pt The equivalent line load generated by the prestressed tendons that are uniformly distributed on the top section of the isolator; The axial pressure line load q G The equivalent line load is caused by the axial pressure uniformly distributed on the top section of the isolator; The uniformly distributed stress As a surface load uniformly distributed on the bottom section of the isolator.

4. The method for determining the bending moment of a cross section according to claim 3, characterized in that, The axial pressure is simplified using the following formula, based on q G Calculate concentrated force : 。 5. The method for determining the bending moment of a cross section according to claim 3, characterized in that, Using the following simplified formula for prestressing, based on q pt Calculate concentrated force F pt : 。 6. The method for determining the bending moment of a cross section according to claim 3, characterized in that, According to L pt Calculate L1 using the following formula: 。 7. The method for determining the bending moment of a cross section according to claim 3, characterized in that, According to L G Calculate L2 using the following formula: 。 8. The method for determining the bending moment of a cross section according to claim 3, characterized in that, According to R ab and r a Calculate L0 using the following formula: 。

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