Method for acquiring rotational rigidity of steel tube tower cross diagonal member node

Abstract

The invention discloses a method for acquiring rotational rigidity of a crossed diagonal member node of a steel tube tower, which comprises the following steps of: S1, acquiring related information, constraint conditions and external load of a left beam and a right beam of the crossed diagonal member node, and establishing a rotational rigidity acquisition model; s2, acting force with a certain magnitude is applied to the crossed diagonal member nodes, the acting force is perpendicular to the plane where the crossed diagonal member nodes are located, and the displacement, perpendicular to the plane, of the crossed diagonal member nodes is obtained; and S3, according to the external load, selecting the rotational rigidity acquisition model, substituting the acting force and the displacement into the selected rotational rigidity acquisition model, and acquiring the rotational rigidity of the crossed diagonal member node. By means of the method, the rotational rigidity of the crossed diagonal member node is acquired while the rotational rigidity precision of the crossed diagonal member node is guaranteed; and the rotational rigidity obtaining efficiency of the crossed diagonal member node is improved.

Description

Technical Field

[0001] The present invention relates to a method for obtaining the rotational stiffness of a cross diagonal member joint of a steel pipe tower, which is applied to obtaining the rotational stiffness of a cross diagonal member joint with asymmetric semi-rigid connection of a steel pipe tower. Background Art

[0002] The X-shaped cross diagonal members (hereinafter referred to as cross diagonal members) of a transmission tower structure belong to the X-shaped cross bracing system, which is mainly used to resist lateral loads such as wind and earthquake. The X-shaped cross bracing system generally consists of two bracing members. Due to the action of lateral forces, they are usually subjected to compression and tension respectively, and are widely used in offshore structures, truss structures, transmission tower structures, etc. The intersection point of the common X-shaped cross bracing system in building engineering is the midpoint, while the intersection point of the cross diagonal members in a transmission steel tower is often not at the midpoint and has the characteristic of non-biaxial symmetry. According to whether the two bracing members are disconnected at the intersection point, it is divided into two cases: continuous two members and one member interrupted at the intersection point. In an angle steel transmission tower, it is more common that the cross diagonal members are connected by two continuous members at the intersection point. In a steel pipe transmission tower, since the cross diagonal members are made of steel pipe members, at least one steel pipe member in the cross bracing system is often disconnected at the intersection point and is connected to another member by means of a node structure such as a gusset plate. The joint connected by this gusset plate is a semi-rigid joint. However, it is difficult to measure and identify the rotational stiffness of the semi-rigid joint of this cross diagonal member, which in turn leads to the inability to accurately calculate the out-of-plane stability bearing capacity of the cross diagonal member. The application of finite element modeling analysis is relatively extensive. Using finite element analysis can often obtain more accurate physical parameters. For example, in the Chinese Patent Network, a method for storing and generating a stiffness matrix in finite element analysis in metal volume plastic forming is disclosed, and its application number is: CN201110130073.9. In this patent, the finite element analysis method is used to analyze the stiffness of metal volume plastic forming. However, using the finite element method requires modeling of the physical object. When measuring the rotational stiffness of cross diagonal member joints of different sizes and shapes, modeling needs to be carried out for each of them, resulting in low efficiency in obtaining the rotational stiffness of cross diagonal member joints.

[0003] The semi-rigid joint structure at the cross diagonal member joint is complex, and it is difficult to obtain its rotational stiffness by displacement measurement when an external force is applied. The existing design calculation method for the out-of-plane stability bearing capacity of cross diagonal members in the current code does not consider the influence of semi-rigid joints. It is found through research that the joint stiffness at the intersection point has an unignorable influence on the bearing capacity of cross diagonal members. Therefore, it is necessary to explore an indirect identification calculation method for the rotational stiffness of the semi-rigid joint of cross diagonal members to more accurately obtain the out-of-plane stability bearing capacity of cross diagonal members for engineering design. Summary of the Invention

[0004] The object of the present invention is to solve the problem that the rotational stiffness of the semi-rigid joints (cross diagonal member joints) of the non-continuous members in the cross diagonal member system of the steel pipe tower is difficult to accurately calculate or directly measure, resulting in insufficient input for calculating the out-of-plane stability bearing capacity of the cross diagonal members. Another object of the present invention is to solve the problem that it is difficult to obtain its rotational stiffness through displacement measurement during external force loading, and improve the efficiency of obtaining the rotational stiffness of the semi-rigid joints of the non-continuous members in the cross diagonal member system of the steel pipe tower.

[0005] To solve the above problems, the present invention provides a method for obtaining the rotational stiffness of the asymmetric semi-rigid connection cross diagonal member joints of a steel pipe tower, including: S1. Obtain the relevant information of the left beam and the right beam of the cross diagonal member joint and the external load, and establish a rotational stiffness acquisition model; S2. Apply a certain magnitude of force perpendicular to the plane where the cross diagonal member joint is located to the cross diagonal member joint, and obtain the displacement of the cross diagonal member joint perpendicular to the plane; S3. According to the external load, select the rotational stiffness acquisition model, substitute the force and the displacement into the selected rotational stiffness model, and obtain the rotational stiffness of the cross diagonal member joint.

[0006] Further, in step S1, the rotational stiffness acquisition model includes: a rotational stiffness acquisition model without external load; the establishment steps of the rotational stiffness acquisition model without external load include: determining the partial differential equations of the left beam and the right beam under no external load, and combining the constraint conditions of the left beam and the right beam to obtain the relationship between the displacement and the rotational stiffness of the cross joint.

[0007] Further, in step S1, the rotational stiffness acquisition model includes: a rotational stiffness acquisition model with external load; the establishment steps of the rotational stiffness acquisition model with external load include: determining the partial differential equations of the left beam and the right beam under external load, and combining the constraint conditions of the left beam and the right beam to obtain the relationship between the displacement and the rotational stiffness of the cross joint.

[0008] Further, in step S3, if the external load is zero, the rotational stiffness acquisition model is a rotational stiffness acquisition model without external load, and the force and the displacement are substituted into the rotational stiffness acquisition model without external load to obtain the rotational stiffness of the cross diagonal member joint.

[0009] Further, in step S3, if the external load is not zero, the rotational stiffness acquisition model is a rotational stiffness acquisition model with external load, and the force and the displacement are substituted into the rotational stiffness acquisition model with external load to obtain the rotational stiffness of the cross diagonal member joint.

[0010] Further, in step S1, the relevant information includes: the rotational stiffness of the left beam and the right beam, and the lengths of the left beam and the right beam.

[0011] Further, the constraint conditions include that the bending moments at the leftmost and rightmost ends of the cross diagonal member joint are 0, and the displacements at the leftmost and rightmost ends of the cross diagonal member joint are 0.

[0012] Further, the constraint conditions include that the bending moment of the cross diagonal member joint is the same as the bending moment at the rightmost end of the left beam.

[0013] Further, the constraint conditions include that the bending moments of the left beam and the right beam at the position of the cross diagonal member joint are the same.

[0014] Further, the constraint conditions include that the shear forces are balanced at any position section of the left beam, the right beam, and the cross diagonal member joint.

[0015] The beneficial effect of the present invention is that the method involved in the present invention is relatively simple in obtaining the rotational stiffness of the cross diagonal member joint. There is no need to perform finite element modeling on the cross diagonal member joint of the steel pipe. By applying a force perpendicular to the plane where the cross diagonal member joint is located to the cross diagonal member joint, the displacement perpendicular to the plane of the cross diagonal member joint is obtained. The rotational stiffness of the cross diagonal member joint of the steel pipe can be obtained through the rotational stiffness acquisition model. And considering the stiffness of the adjacent beams, the accuracy of the obtained rotational stiffness of the cross diagonal member joint is relatively high. Description of the Drawings

[0016] Figure 1 It is a flow chart of the method involved in the present invention.

[0017] Figure 2 It is a schematic diagram of a simplified beam model of a discontinuous rod.

[0018] Figure 3 It is a schematic diagram of an asymmetric semi-rigid connection cross joint of a steel pipe tower.

[0019] Figure 4 It is a schematic diagram of a brief structure modeled by ANSYS finite element software.

[0020] Figure 5 It is a schematic diagram of a brief structure modeled by ANSYS finite element software.

[0021] Figure 6 It is a schematic diagram of the structure modeled by ANSYS finite element software. Detailed Embodiments

[0022] Embodiment 1. This embodiment discloses the specific implementation process of the method involved in the present invention. Refer to Figure 1 .

[0023] In this embodiment, the specific process of the method involved in the present invention is as follows.

[0024] S1. Obtain the relevant information and external loads of the left beam and the right beam of the cross diagonal member node, and establish a rotational stiffness acquisition model.

[0025] In step S1, the relevant information of the left beam and the right beam of the cross diagonal member node includes: the stiffness of the left beam and the right beam; the lengths of the left beam and the right beam.

[0026] In step S1, the rotational stiffness acquisition model includes: a rotational stiffness acquisition model without external loads and a rotational stiffness acquisition model with external loads, and it is necessary to establish a rotational stiffness acquisition model without external loads and a rotational stiffness acquisition model with external loads.

[0027] The steps for establishing the rotational stiffness acquisition model without external loads and the rotational stiffness acquisition model with external loads are as follows.

[0028] Establish a vertical displacement function of the left beam with the abscissa of the left beam as the independent variable and the vertical displacement of the left beam as the dependent variable.

[0029] Establish a vertical displacement function of the right beam with the abscissa of the right beam as the independent variable and the vertical displacement of the right beam as the dependent variable.

[0030] The initial abscissa of the left beam is the leftmost position of the cross diagonal member node, and the initial abscissa of the right beam is the abscissa of the cross diagonal member node position, or the initial abscissa of the left beam is the abscissa of the cross diagonal member node position, and the initial abscissa of the right beam is the rightmost position of the cross diagonal member node.

[0031] That is, the maximum abscissa of the left beam is the same as the initial abscissa of the right beam, or the initial abscissa of the left beam is the same as the maximum abscissa of the right beam.

[0032] In this embodiment, the initial abscissa of the left beam is the leftmost position of the cross diagonal member node, and the initial abscissa of the right beam is the abscissa of the cross diagonal member node position.

[0033] Establish partial differential equations for the left beam and the right beam respectively, and obtain the general solutions of the vertical displacement function of the left beam and the vertical displacement function of the right beam through the partial differential equations of the left beam and the right beam.

[0034] The partial differential equation of the left beam is: the stiffness of the left beam multiplied by the fourth derivative of the vertical displacement function of the left beam with respect to the abscissa of the left beam, plus the external load multiplied by the second derivative of the vertical displacement function of the left beam with respect to the abscissa of the left beam, to obtain the value of the partial differential equation of the left beam, and this value is 0.

[0035] Its expression is: where E₁I₁ is the stiffness of the left beam, P is the external load, and y₁(x₁) is the vertical displacement function of the left beam.

[0036] The partial differential equation of the right beam is: the stiffness of the right beam multiplied by the fourth derivative of the vertical displacement function of the right beam with respect to the abscissa of the right beam, plus the external load multiplied by the second derivative of the vertical displacement function of the right beam with respect to the abscissa of the right beam, to obtain the value of the partial differential equation of the right beam, and this value is 0.

[0037] Its expression is: Where, E2I2 is the stiffness of the right beam, P is the external load, and y1(x1) is the vertical displacement function of the right beam.

[0038] Perform dimensionless processing on the parameters in the partial differential equations of the left beam and the right beam. The processing method is as follows.

[0039] Perform dimensionless processing on the vertical displacement and abscissa of the left beam. Specifically: the vertical displacement of the left beam is divided by the length of the left beam; the abscissa of the left beam is divided by the length of the left beam.

[0040] Its expression is: y'1 = y1 / l1, x'1 = x1 / l1, where l1 is the length of the left beam.

[0041] Perform dimensionless processing on the vertical displacement and abscissa of the right beam. Specifically: the vertical displacement of the right beam is divided by the length of the right beam; the abscissa of the right beam is divided by the length of the right beam.

[0042] Its expression is: y'2 = y2 / l2, x'2 = x2 / l2, where l2 is the length of the left beam.

[0043] Obtain the dimensionless partial differential equations of the left beam and the right beam as follows.

[0044] The dimensionless partial differential equation of the left beam is: Where,

[0045] The dimensionless partial differential equation of the right beam is: Where,

[0046] If the value of the external load is zero, the general solutions of the vertical displacement functions of the left beam and the right beam are as follows.

[0047] The general solution of the vertical displacement function of the left beam is: Where, C 11 , C 21 , C 31 , C 41 are all constants.

[0048] The general solution of the vertical displacement function of the right beam is: Where, C 12 , C 22 , C 32 , C42 All are constants.

[0049] If the value of the external load is not zero, the general solutions of the vertical displacement functions of the left beam and the right beam are as follows.

[0050] The general solution of the vertical displacement function of the left beam is: Where C 11 , C 21 , C 31 , C 41 All are constants.

[0051] The general solution of the vertical displacement function of the right beam is: Where C 12 , C 22 , C 32 , C 42 All are constants.

[0052] After determining the general solutions of the left beam and the right beam under external load and no external load respectively, according to the relevant constraint conditions of the left beam and the right beam, the relationship between the displacement and the acting force magnitude of the cross diagonal member node is determined, and the rotational stiffness acquisition model under no external load is obtained.

[0053] The relevant constraint conditions of the left beam and the right beam are as follows.

[0054] The relevant constraints of the left beam and the right beam include: when the cross diagonal member node is subjected to a force perpendicular to the plane where the cross diagonal member node is located, the bending moments at the leftmost and rightmost ends of the cross diagonal member node are 0, and the displacements at the leftmost and rightmost ends of the cross diagonal member node are 0.

[0055] Its expression is:

[0056] The relevant constraints of the left beam and the right beam include: when the cross diagonal member node is subjected to a force perpendicular to the plane where the cross diagonal member node is located, the bending moment of the cross diagonal member node is the same as the bending moment at the rightmost end of the left beam.

[0057] Its expression is: Where λ is the relative stiffness of the semi-rigid node, k θ is the rotational stiffness of the cross diagonal member node.

[0058] The relevant constraints of the left beam and the right beam include: when the cross diagonal member node is subjected to a force perpendicular to the plane where the cross node is located, the bending moments of the left beam and the right beam at the cross diagonal member node are the same.

[0059] Its expression is: Where a is the relative position of the cross-beam node, l is the sum of the lengths of the left and right beams;

[0060] The relevant constraints of the left beam and the right beam include: when the cross-diagonal node is subjected to a force perpendicular to the plane where the cross-diagonal node is located, the vertical displacements of the left beam and the right beam at the cross-diagonal node are the same.

[0061] Its expression is:

[0062] The relevant constraints of the left beam and the right beam include: when the cross-diagonal material node is subjected to a force perpendicular to the plane where the cross-diagonal material node is located, the shear force balance of the cross section at any position of the left beam, the right beam and the cross-diagonal material node.

[0063] Take the position interface of the cross-bevel node as an example.

[0064] Its expression is: Among them, F ‘ is the dimensionless vertical load, F is the force acting on the cross-diagonal joint (the cross-diagonal joint is subject to a force perpendicular to the plane in which the cross-diagonal joint is located). After determining the relevant constraints of the left and right beams, the relationship between the vertical displacement of the cross-diagonal joint and the rotational stiffness acting on the cross-diagonal joint is obtained based on the relevant constraints of the left and right beams and the general solution of the partial differential equations for the left and right beams.

[0065] Combining the general solution of the partial differential equations of the left and right beams without external loads and the relevant constraints of the left and right beams, the relationship between the vertical displacement of the cross-diagonal node and the rotational stiffness acting on the cross-diagonal node is obtained.

[0066] Considering that the stiffness of the left beam and the right beam are the same, the expression of this relationship is:

[0067] Considering the different stiffness of the left and right beams, the expression of this relationship is:

[0068] Combining the general solution of the left and right beams under external loads and the relevant constraints of the left and right beams, the relationship between the vertical displacement of the cross-diagonal member node and the rotational stiffness acting on the cross-diagonal member node is obtained.

[0069] Considering that the stiffness of the left beam and the right beam are the same, the expression of this relationship is:

[0070] Considering the case where the stiffness of the left beam and the right beam are different, the expression of this relationship is:

[0071] After establishing the stiffness acquisition model, step S2 is then executed.

[0072] Execute step S2, apply a force perpendicular to the plane where the cross diagonal member joint is located to the cross diagonal member joint, and obtain the vertical displacement of the cross diagonal member joint under this force.

[0073] Refer to Figure 2 , in the figure, there are three points A, B, and C. Among them, A is the leftmost end of the cross diagonal member joint, B is the cross diagonal member joint, C is the rightmost end of the cross diagonal member joint, AB is denoted as the left beam, and BC is denoted as the right beam.

[0074] Under the action of the force F, the joint B generates a vertical displacement relative to the plane where the joints A and C are located, that is, the perpendicular distance between the joint B and the plane AC.

[0075] The condition that the force F acts on the cross diagonal member joint is: the direction of the force F is perpendicular to the plane where the cross diagonal member joint is located.

[0076] Therefore, there is no specific restriction on the direction of the force F, and it only needs to satisfy being perpendicular to the plane where the cross diagonal member joint is located. Taking this figure as an example, the abscissa of the left beam is the leftmost end of the cross diagonal member joint, and the vertical displacement of each point on the left beam is the perpendicular distance between this point and the plane AC; the abscissa of the right beam is at the position of the cross diagonal member joint, and the vertical displacement of each point on the right beam is the perpendicular distance between this point and the plane AC.

[0077] Refer to Figure 3 , when measuring Figure 3 the semi-rigid asymmetric cross diagonal member joint of the steel pipe in, first determine the plane where the cross diagonal member joint is located. After determining the plane where the cross diagonal member joint is located, apply a force perpendicular to this plane to the cross diagonal member joint, and obtain the vertical displacement of the cross diagonal member joint.

[0078] Execute step S3, determine the stiffness acquisition model according to the external load, substitute the vertical displacement of the cross diagonal member joint and the force applied to the cross diagonal member joint into the selected stiffness acquisition model, and obtain the rotational stiffness of the cross diagonal member joint.

[0079] If the value of the external load is zero, the stiffness acquisition model is the stiffness acquisition model without external load; if the value of the external load is not zero, the stiffness acquisition model is the stiffness acquisition model with external load.

[0080] Obtain the model according to the selected stiffness and obtain the rotational stiffness of the cross-bracing joint.

[0081] If the rotational stiffness acquisition model is the no-load stiffness acquisition model, substitute the vertical displacement of the cross-bracing joint and the force applied to the cross-bracing joint into the selected stiffness model to obtain the rotational stiffness of the cross-bracing joint.

[0082] If the stiffness of the left beam and the right beam of the cross-bracing joint is the same, the rotational stiffness of the cross-bracing joint is:

[0083] If the stiffness of the left beam and the right beam of the cross-bracing joint is different, the rotational stiffness of the cross-bracing joint is:

[0084] If the rotational stiffness acquisition model is the external load stiffness acquisition model, substitute the vertical displacement of the cross-bracing joint and the force applied to the cross-bracing joint into the selected stiffness model.

[0085] If the stiffness of the left beam and the right beam of the cross-bracing joint is the same, the rotational stiffness of the cross-bracing joint is:

[0086] If the stiffness of the left beam and the right beam of the cross-bracing joint is different, the rotational stiffness of the cross-bracing joint is:

[0087] Through the above formulas, the rotational stiffness of the cross-bracing joint in different cases can be obtained.

[0088] By the method of this embodiment, when measuring the rotational stiffness of the asymmetric semi-rigid cross-bracing joint of the steel pipe tower, the technical personnel only need to apply a force perpendicular to the plane where the cross-bracing joint is located to the cross-bracing joint and obtain the vertical displacement of the cross-bracing joint, then the rotational stiffness of the cross-bracing joint can be obtained. While ensuring the accuracy of the rotational stiffness, the process of establishing the finite element model is eliminated, which can effectively reduce the workload of the technical personnel of the transmission tower.

[0089] Embodiment 2, this embodiment discloses the effect of the specific implementation of the method of the present invention.

[0090] In this example, a finite element bar system model of the discontinuous bars in the semi-rigid connection cross-bracing system will be established in the finite element software; a vertical unit force perpendicular to the beam direction will be applied at the intersection points of the finite element bar system model of the discontinuous bars, and the vertical displacements at the intersection points will be extracted by post-processing. Based on the identification calculation method given in the present invention, the rotational stiffness of the semi-rigid joints will be calculated, and compared with the analysis results directly extracted from the finite element bar system model to verify the effectiveness and progressiveness of the method of the present invention. In addition, the effective length of the elastic buckling bearing capacity will be obtained by substituting the rotational stiffness of the semi-rigid joints identified by the present invention into the finite element bar system model of the cross-bracing system, and compared with the effective length calculated directly by using the solid element finite element model to further verify the effectiveness and progressiveness of the method of the present invention.

[0091] The process of establishing the finite element bar system model of the discontinuous bars in the semi-rigid connection cross-bracing system is as follows: As Figure 4 shown, the discontinuous steel pipe members in the cross diagonal member system are established by using 189 beam elements. The unit section properties are selected as hollow circles. The left end of the model is constrained in the x, y, and z direction displacements, and the right end is constrained in the y and z direction displacements. The middle connection between the left and right beams is hinged, and the nodes of the two beam elements at the connection are coupled. The combin14 unit is used for constraint to simulate the semi-rigid joints. The unit material is steel, and the elastic modulus E is taken as 2.06×105 MPa. The elastic theory model is adopted, and the loading is carried out by applying force at the middle node.

[0092] According to the above finite element method, the discontinuous bar members of the cross diagonal members of 6 steel pipe towers with different sizes in the actual project are analyzed, and the analysis results are compared with the calculation results of the identification formula provided by the method of the present invention. The comparison results are shown in Table 1 below.

[0093] Table 1. Comparison of node displacement results.

[0094] Note: D is the outer diameter of the steel pipe;

[0095] T is the thickness of the steel pipe.

[0096] L2. The establishment process of the finite element bar system model of the semi-rigid connection cross-bracing system is similar to that of the finite element bar system model of the discontinuous bars: As Figure 5 shown, the discontinuous and continuous steel pipe members in the cross diagonal member system are established by using 189 beam elements. The unit section properties are selected as hollow circles. The left end of the discontinuous member is constrained in the x, y, and z direction displacements, and the right end is constrained in the y and z direction displacements. The constraints of the continuous members are the same. The middle connection between the left and right beams of the discontinuous member is hinged, and the nodes of the two beam elements at the connection are coupled. The combin14 unit is used for constraint to simulate the semi-rigid joints. The unit material is steel, the elastic model E is 2.06×105MPa, and the elastic theory model is adopted.

[0097] L3. The process of establishing the solid unit finite element model of the semi-rigid connection cross support system is as follows: like Figure 6 As shown in the figure, a solid unit finite element model of asymmetric semi-rigid connection cross diagonal material was established using ANSYS finite element software.

[0098] The steel pipes, plates, ribs, and bolts were all modeled using three-dimensional solid elements, namely SOLID185 elements. All contacts were implemented using CONTA174 and TARGE170 contact pair elements. The model's boundary conditions and loading scheme were as follows: rigid rods were placed at each end of the steel pipe, and all nodes at the end were extended to a central point in a wheel-like manner to simulate simply supported conditions at the ends. Loads were applied at the nodes or at the center of the pipe ends. Force loading was used, and geometric nonlinearity was considered during loading, with large deformation control enabled. The elastic modulus of all steel materials was E = 2.0 × 105 MPa, and the Poisson's ratio v = 0.3.

[0099] According to the above two finite element methods L2 and L3, the cross diagonals of the six steel tube towers with different sizes in Table 1 were analyzed, and the effective length coefficients of the buckling bearing capacity of the finite element solid unit model and the finite element bar system model were obtained. The semi-rigid node stiffness of the finite element bar system model is obtained according to the identification calculation method of the present invention. Each working case gives the results of three cases: the continuous member is in tension, no load and in compression. The comparison results are shown in Table 2 below.

[0100] Table 2. Comparison of the effective length coefficients of elastic buckling capacity between the finite element solid element model and the finite element bar system model.

[0101] Note: μ is the effective length coefficient of elastic buckling capacity of discontinuous rod;

[0102] β is the ratio of the load on the continuous member to the load on the discontinuous member.

[0103] As can be seen from Table 1, the relative errors of the displacement results obtained by the finite element analysis and the displacement results obtained by the stiffness identification method proposed in the present invention are both 0.00% when the number of effective decimal places is 3.

[0104] Secondly, as can be seen from Table 2, when the node stiffness identified by the present invention is substituted into the finite element bar system model, the effective length of the elastic buckling bearing capacity obtained by the analysis has a smaller error than the effective length obtained by the finite element solid unit model analysis, with the maximum error being only 6.46%.

[0105] It shows that the rotational stiffness obtained by the method involved in the present invention has high accuracy. Compared with the finite element analysis method, the establishment process of the finite element model is eliminated, which can effectively reduce the workload of transmission tower technicians, realizes the indirect measurement and identification of the semi-rigid joint stiffness, and provides key input parameters for the calculation of the out-of-plane stability bearing capacity of the cross braces with semi-rigid connections in steel pipe towers.

[0106] The present invention deeply explains its purpose, technical solution and beneficial effects through specific embodiments. However, these embodiments are only examples to show the application modes of the invention and do not constitute a limitation to the protection scope of the present invention. We clearly point out that any reasonable modification, equivalent replacement or technical improvement under the guidance of the spirit and principle of the present invention should be included in the protection scope of the present invention. This means that as long as these changes do not deviate from the core idea and basic functions of the invention, they should be protected by the patent right. The protection scope of the present invention should be broad, including all direct and obvious variants as well as non-obvious innovations that can be reasonably deduced by technical experts based on the disclosed content of the present invention. This broad protection aims to promote further research and development based on the present invention while ensuring that its innovation and practicality are comprehensively protected by law.

Claims

1. A method for obtaining the rotational stiffness of the cross diagonal member joint of a steel pipe tower, characterized in that Including: S1. Obtain the relevant information, constraint conditions and external loads of the left beam and the right beam of the cross diagonal member node, and establish a rotational stiffness acquisition model; S2. Apply a certain magnitude of force to the cross diagonal member node, the force is perpendicular to the plane where the cross diagonal member node is located, and obtain the displacement of the cross diagonal member node perpendicular to the plane; S3. According to the external load, select the rotational stiffness acquisition model, substitute the force and the displacement into the selected rotational stiffness acquisition model, and obtain the rotational stiffness of the cross diagonal member node.

2. The method for obtaining the rotational stiffness of a cross diagonal member joint of a steel pipe tower according to claim 1, characterized in that, In step S1, the rotational stiffness acquisition model includes: a rotational stiffness acquisition model without external load; the establishment steps of the rotational stiffness acquisition model without external load include: determining the partial differential equations of the left beam and the right beam without external load, and combining the constraint conditions of the left beam and the right beam to obtain the relationship between the displacement and the rotational stiffness of the cross diagonal member node.

3. The method for obtaining the rotational stiffness of the cross diagonal member joint of a steel pipe tower according to claim 1, characterized in that, In step S1, the rotational stiffness acquisition model includes: a rotational stiffness acquisition model with external load; the establishment steps of the rotational stiffness acquisition model with external load include: determining the partial differential equations of the left beam and the right beam under external load, and combining the constraint conditions of the left beam and the right beam to obtain the relationship between the displacement and the rotational stiffness of the cross diagonal member node.

4. A method for obtaining the rotational stiffness of a cross diagonal member joint of a steel pipe tower according to claim 2, characterized in that, In step S3, if the external load is zero, the rotational stiffness acquisition model is a rotational stiffness acquisition model without external load, substitute the force and the displacement into the rotational stiffness acquisition model without external load, and obtain the rotational stiffness of the cross diagonal member node.

5. The method for obtaining the rotational stiffness of the cross diagonal member joint of a steel pipe tower according to claim 3, characterized in that, In step S3, if the external load is not zero, the rotational stiffness acquisition model is a rotational stiffness acquisition model with external load, substitute the force and the displacement into the rotational stiffness acquisition model with external load, and obtain the rotational stiffness of the cross diagonal member node.

6. A method for obtaining the rotational stiffness of a cross diagonal member joint of a steel pipe tower according to any one of claims 1 to 5, characterized in that In step S1, the relevant information includes: the rotational stiffness of the left beam and the right beam, and the lengths of the left beam and the right beam.

7. A method for obtaining the rotational stiffness of a cross diagonal member joint of a steel pipe tower according to any one of claims 1 to 5, characterized in that The constraint conditions include: the bending moments at the leftmost and rightmost ends of the cross diagonal member node are zero, and the displacements at the leftmost and rightmost ends of the cross diagonal member node are zero.

8. A method for obtaining the rotational stiffness of a cross diagonal member joint of a steel pipe tower according to any one of claims 1 to 5, characterized in that, The constraint conditions include: the bending moment of the cross diagonal member node is the same as the bending moment at the rightmost end of the left beam.

9. A method for obtaining the rotational stiffness of a cross diagonal member joint of a steel pipe tower according to any one of claims 1 to 5, characterized in that, The constraint conditions include: the bending moments of the left beam and the right beam at the position of the cross diagonal member node are the same.

10. A method for obtaining the rotational stiffness of a cross diagonal member joint of a steel pipe tower according to any one of claims 1 to 5, characterized in that The constraint conditions include: the shear force balance at any position section of the left beam, the right beam and the cross diagonal member node.

Images