Practical modeling method for spatially twisted steel structure

Abstract

The application provides a practical modeling method for a space torsion steel structure, and belongs to the technical field of steel structures, namely: a three-dimensional simulation model of a space torsion steel component is established by using a three-dimensional modeling software, the relationship between the space torsion steel component and the whole structure is determined according to the simulation model, and the three-dimensional simulation model is imported into a calculation analysis software through a general file format; the boundary conditions of the space torsion steel component are determined through the stress of the whole structure according to the principle of stress equivalence, and finally the modeling of the space torsion steel component is completed. The application can solve the problems that large space steel components, especially the space torsion steel components with complex shapes are difficult to model and calculate, ensure the modeling precision, and maximize the equivalence of the stress, and is practical.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel structure, and particularly relates to a practical modeling method for a space torsion steel structure. BACKGROUND

[0002] The space torsion surface curved tower cable-stayed bridge is a relatively new structural form, and in the case of a 200m span, compared with other similar span bridge modeling schemes, the tower modeling is more beautiful and fashionable, the visual effect is prominent, the effect of improving the cityscape is obvious, and the landmark effect is prominent. The tower body types of the traditional single-tower cable-stayed bridge generally include single-column type, double-column type, door type, H type, A type, diamond type, inverted Y type and vase type and the like. These tower types have relatively regular geometric shapes of the tower body, and a large amount of engineering experience can be referred to, and can be designed according to the existing specifications. In the main tower structure of the space torsion surface curved tower cable-stayed bridge, a large number of space torsion surface steel plates are adopted, and the cable surface is also a space torsion surface. Compared with the traditional cable-stayed bridge, the stress performance and ultimate bearing capacity of the space torsion steel member cannot be analyzed by the traditional method, and therefore, the space torsion steel member must be analyzed and a reasonable structure must be determined by means of refined finite element modeling.

[0003] To solve the above problems, the application introduces a three-dimensional modeling method to solve the problem that large space steel members, especially space torsion-shaped steel members with complex modeling, are difficult to model and calculate. SUMMARY

[0004] The application aims to provide a practical modeling method for a space torsion steel structure, which is characterized by comprising the following steps:

[0005] S1: establishing a three-dimensional simulation model of components such as a main beam, a main tower and a cable-stayed cable in a three-dimensional modeling software;

[0006] S2: merging the components into a three-dimensional simulation whole model;

[0007] S3: intercepting a three-dimensional simulation model of a local space torsion steel member in the three-dimensional simulation whole model;

[0008] S4: importing the three-dimensional simulation model of the space torsion steel member into a calculation analysis software through a general file format;

[0009] S5: in the calculation analysis software, dividing different segments according to specific design drawings to obtain segmented model components, and assigning thicknesses of shell elements to the model components respectively through cross-section characteristics definition;

[0010] S6: determining boundary conditions of the space torsion steel member through overall structure stress according to the stress equivalent principle to complete modeling of the space torsion steel member.

[0011] Further, in S1, the main girder comprises a top plate, a bottom plate, a web plate, a transverse partition plate and a small longitudinal beam, etc.; the main tower is a spatially twisted face arch tower, comprising an outer wall, an inner cylinder, a transverse partition plate and a cable tower area steel anchor beam.

[0012] Further, the web plate comprises a curved web plate and a straight web plate, the curved web plate is established according to a spatial curve lofting in a three-dimensional modeling software, and the straight web plate is established by stretching at a specific distance; the inner cylinder comprises an inner cylinder top and bottom plate and an inner cylinder web plate.

[0013] Further, the inner cylinder and the outer wall are both provided with stiffening ribs.

[0014] Further, in S3, the three-dimensional simulation model of the spatially twisted steel member comprises four fixed nodes and four sections due to truncation; in S6, the force equivalence with the overall model is realized by applying corresponding loads and boundaries on the four sections.

[0015] Further, the sections are arranged away from the fixed nodes to ensure that the local truncation does not affect the force.

[0016] Further, in S6, multi-point constraints are adopted to ensure that the load can be uniformly transmitted to the member section, so as to achieve the purpose of applying equivalent loads and determining equivalent boundaries.

[0017] Further, the multi-point constraint is to take one or more degrees of freedom of a specified node as a standard value, and to establish a relationship between the relevant degrees of freedom of other nodes and the specified node.

[0018] Compared with the prior art, the three-dimensional modeling of the spatially twisted steel member is realized to solve the problem that large spatial steel members, especially spatially twisted steel members with complex shapes, are difficult to model and calculate, and the modeling precision is ensured, and the force equivalence is maximized to ensure the practicability. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is an overall elevation arrangement diagram of an embodiment of the present application;

[0020] Figure 2 It is an overall elevation arrangement diagram of an embodiment of the present application; Figure 1 It is an elevation view of the spatially twisted steel member in the embodiment shown;

[0021] Figure 3 It is an elevation view of the spatially twisted steel member in the embodiment shown; Figure 1 It is a side view of the spatially twisted steel member in the embodiment shown. DETAILED DESCRIPTION

[0022] The practical modeling method of a space twisted steel structure will be described in more detail below in connection with the schematic diagram, which shows the preferred embodiment of the present application, and it should be understood that the present application described herein can be modified by those skilled in the art while still achieving the advantageous effects of the present application, therefore, the following description should be understood as the extensive knowledge of those skilled in the art, and not as a limitation of the present application.

[0023] As shown in Figures 1-3 , a practical modeling method of a space twisted steel member, comprising the following steps:

[0024] 1) : respectively establish three-dimensional simulation models of main girder, main tower and cable-stayed cable and other components in three-dimensional modeling software. Among them, the main girder model includes top plate, bottom plate, web plate, transverse diaphragm, small longitudinal beam and other structures, the web plate includes curved web plate and straight web plate, the curved web plate is established according to the space curve lofting in three-dimensional modeling software, and the straight web plate is established by stretching a certain distance; the shape of the main tower is a space twisted surface arch tower, and the main structure includes outer wall, inner cylinder, transverse diaphragm, cable tower area steel anchor beam, the inner cylinder is divided into inner cylinder top and bottom plate and inner cylinder web plate, and the inner cylinder and the outer wall are respectively arranged with stiffening ribs. Among them, the three-dimensional software can be SolidWorks, rhino and the like.

[0025] 2) : combine each component into a three-dimensional simulation whole model.

[0026] 3) : intercept the three-dimensional simulation model of the local space twisted steel member in the three-dimensional simulation whole model.

[0027] Considering the calculation efficiency of the model, no stiffening rib entity is established in the calculation process, but the equivalent plate thickness method is adopted to consider the influence of the mass of the stiffening rib, and the contribution of the stiffness of the stiffening rib is ignored. In order to save the amount of calculation, and more completely consider the influence of the stiffening rib, in order to obtain more accurate stress results of the calculation results of the space twisted steel member, the local model of the space twisted steel member is intercepted on the basis of the whole model, and the local model of the space twisted steel member is intercepted from the whole model which is built first, and contains four fixed nodes.

[0028] The main grid of the tower beam fixed local model adopts 400mm, the four local fixed areas in the structure which need to be optimized in structure to solve the stress concentration problem adopt 200mm of encryption grid.

[0029] The local model of the spatial torsion steel member has four sections due to truncation, and the force of the sections is equivalent to the force of the whole model by adding corresponding loads and boundaries. The tower column retains the triangular area below the main beam, and the tower column above the main beam is truncated at the transverse diaphragm at the appropriate position. The position of the truncated section is a certain distance away from the tower beam fixed point to ensure that the local truncation basically does not affect the force. The main beam is truncated at the appropriate position in the longitudinal direction, and the truncated position is a certain distance away from the tower beam fixed point and the leg beam fixed point to ensure that the force of the four nodes is basically not affected.

[0030] 4) Import the three-dimensional simulation model of the spatial torsion steel member into the calculation analysis software through the universal file format. The calculation analysis software is ABAQUS, ANSYS and the like.

[0031] 5) In the calculation analysis software, different sections are divided according to specific design drawings to obtain the segmented model components, and the thickness of the shell element of the model components is assigned respectively through the section property definition.

[0032] 6) In order to better simulate the force of the spatial torsion steel member model, the MPC (Multi-Point Constraints) is selected to ensure that the load can be uniformly transmitted to the member section according to the force equivalence principle, so as to achieve the purpose of applying equivalent load and determining equivalent boundary.

[0033] The MPC is to take one or more degrees of freedom of a node as a standard value, and to specify the related degrees of freedom of other nodes to establish a relationship. In the model of the present example, reference points are created at the corresponding sections of the tower column, MPC constraints are created on the whole plane, different local coordinate systems are established, three concentrated forces and three concentrated bending moment loads are created, and the MPC constraints are uniformly transmitted to the whole section. Similarly, reference points are also created at the corresponding sections of the main beam, MPC constraints are created on the whole plane, different local coordinate systems are established, three concentrated forces and three concentrated bending moment loads are created, and the MPC constraints are uniformly transmitted to the whole section. The corresponding boundary is set on the pair of box girders of the double main beam.

[0034] The above is only the preferred embodiment of the present application, and does not limit the present application in any way. Any person skilled in the art can make any form of equivalent replacement, modification or change to the technical solutions and technical contents disclosed by the present application without departing from the scope of the technical solutions of the present application, which still belongs to the protection scope of the present application.

Claims

1. A practical modeling method for spatial torsional steel structures, characterized in that, Includes the following steps: S1: Create a 3D simulation model of each component of the bridge in 3D modeling software; S2: Merge all components into a three-dimensional simulation model; S3: Extract a local spatial torsion steel component 3D simulation model from the overall 3D simulation model; S4: Import the 3D simulation model of the spatial torsion steel member into the calculation and analysis software using a common file format; S5: In the calculation and analysis software, different segments are divided according to the specific design drawings to obtain the segmented model components. The thickness of the shell element is assigned to the model components by defining the cross-sectional properties. For components with stiffening ribs, the shell element thickness is assigned by using the equivalent plate thickness method to take into account the influence of the stiffening rib mass. S6: Based on the principle of force equivalence, the boundary conditions of the spatial torsion steel member are determined by the overall structural force, and the modeling of the spatial torsion steel member is completed. Among them, a local coordinate system is established at the cross section of the spatial torsion steel member, and the load is uniformly transferred to the cross section through multi-point constraints. In S1, the bridge structure includes a main girder, a main tower, and cable stays; the main girder includes a top plate, a bottom plate, a web, transverse diaphragms, and small longitudinal beams; the main tower is a spatially twisted arch tower, including an outer wall, an inner cylinder, transverse diaphragms, and steel anchor beams in the tower area.

2. The practical modeling method for spatial torsion steel structures according to claim 1, characterized in that, The web includes a curved web and a straight web. The curved web is created by lofting a spatial curve in 3D modeling software, and the straight web is created by stretching a specific distance. The inner cylinder includes an inner cylinder top and bottom plate and an inner cylinder web.

3. The practical modeling method for spatial torsion steel structures according to claim 2, characterized in that, Both the inner cylinder and the outer wall are provided with stiffening ribs.

4. The practical modeling method for spatial torsion steel structures according to claim 1, characterized in that, In step S3, the three-dimensional simulation model of the spatial torsion steel member includes four fixed nodes and four cross sections generated by truncation; in step S6, the force equivalence with the overall model is achieved by applying corresponding loads and boundaries to the four cross sections.

5. The practical modeling method for spatial torsion steel structures according to claim 4, characterized in that, The cross section is positioned away from the fixed joint to ensure that the local truncation does not affect the stress.

6. The practical modeling method for spatial torsion steel structures according to claim 4, characterized in that, In S6, multi-point constraints are used to ensure that the load can be uniformly transferred to the component section, so as to achieve the purpose of applying equivalent load and determining equivalent boundary.

7. The practical modeling method for spatial torsion steel structures according to claim 6, characterized in that, The multi-point constraint uses one or more degrees of freedom of a specified node as the standard value to establish a relationship between the relevant degrees of freedom of other nodes and the specified node.

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