A method for automatic reconstruction of complex BIM in finite element platform

Abstract

The present invention discloses a method for automatically reconstructing a complex BIM in a finite element platform, which relates to the technical field of finite element platforms. The method involves obtaining the geometric dimension information, spatial position information, physical parameter information, and contact information of all final bodies in the model in the BIM platform; disassembling the final body to obtain the Boolean operation of forming the final body from the basic body, and obtaining the external computational geometry feature information of the basic body, process body, and final body; selecting the corresponding body in the finite element platform based on the Boolean operation and external computational geometry feature information obtained from the disassembly of the final body, performing Boolean operation on the corresponding body, and reconstructing the final body; selecting the corresponding final body to establish contact, and assigning the corresponding physical parameter information to the final body. The present invention realizes the automatic geometric reconstruction, automatic contact establishment, and automatic attribute assignment of the BIM model in the finite element platform.

Description

Technical Field

[0001] The present invention relates to the technical field of finite element platforms, and in particular to a method for automatically reconstructing a complex BIM in a finite element platform. Background Art

[0002] Finite element analysis for BIM (Building Information Modeling) is currently a hot topic in engineering research. The most common approach is to extract relevant geometry and attribute information from BIM and then automatically regenerate it using the parametric modeling capabilities of the finite element platform, thereby enabling BIM finite element analysis. For example, Chinese invention patent CN116305418A discloses a method for converting mesh structure BIM models and point cloud models into finite element models. This method captures information such as the mesh structure's centerline, nodes, cross-sections, and materials in BIM, and reconstructs it within the finite element platform through a command stream, automatically enabling BIM finite element analysis.

[0003] However, this method is only suitable for finite element analysis of BIMs assembled from simple geometric elements. It is not suitable for BIMs with complex geometric elements (derived from Boolean operations on multiple geometric elements). This is because during the Boolean operation, the bodies participating in the operation are first deleted, and then the final body is regenerated (the regenerated final body does not inherit any information from the original bodies participating in the Boolean operation). This process can cause the program to lose the selected target during the reconstruction, making automation impossible. Summary of the Invention

[0004] In order to overcome the defects in the above-mentioned prior art, the present invention provides a method for automatically reconstructing complex BIM in a finite element platform. By obtaining the geometric feature information of the basic body, process body and final body, the object is accurately selected, thereby avoiding the loss of the selected target during the automatic reconstruction process of the program.

[0005] To achieve the above object, the present invention adopts the following technical solutions, including:

[0006] A method for automatically reconstructing a complex BIM in a finite element platform includes the following steps:

[0007] S1, obtain the geometric size information, spatial position information, physical parameter information and contact information of all final bodies in the model in the BIM platform;

[0008] The final body refers to a geometric body that is continuous in space and has the same physical parameter information;

[0009] S2, disassemble the final body, obtain the Boolean operation of forming the final body from the basic body, record the corresponding Boolean operation, and obtain the geometric feature information of the basic body, the process body and the final body, which is recorded as the external calculated geometric feature information;

[0010] The basic body refers to a geometric body directly generated by given parameters in the finite element platform;

[0011] The process body refers to a geometric body that has undergone at least one Boolean operation on the basic body but has not yet formed a final body;

[0012] The geometric feature information includes volume, center of mass, moment of inertia and product of inertia;

[0013] S3, based on the Boolean operation obtained by disassembling the final body and the external computational geometry feature information, the corresponding body is selected in the finite element platform to perform the Boolean operation and reconstruct the final body;

[0014] S4, selecting a corresponding final body to establish contact based on the external computational geometric feature information, and assigning corresponding physical parameter information to the final body.

[0015] Preferably, in step S2, the external geometric feature information of the basic body, the process body and the final body is calculated in the following manner:

[0016] S21, set three groups of dividing surfaces in space, each dividing surface in each group is parallel to each other and arranged at equal intervals, and the dividing surfaces in different groups are perpendicular to each other; the spacing is a ;

[0017] S22, using three sets of dividing faces to divide the body into multiple volumes no larger than a 3 The unit of ; where the volume is equal to a 3 The unit with a volume smaller than a 3 The unit is called an equivalent unit; the body refers to the basic body, process body or final body;

[0018] S23, converting the equal-generation unit into a polyhedron by equal-generation replacement; the equal-generation replacement means replacing the faces of the equal-generation unit that do not coincide with the dividing plane with a fitting plane; the fitting replacement satisfies that the sum of the squares of the distances of all edge intersections projected onto the fitting plane is minimized; the edge intersections are the intersections of the faces of the equal-generation unit that do not coincide with the dividing plane and the intersecting edges; the intersecting edges are the intersection lines formed by the intersection of all the dividing planes;

[0019] S24, calculate the volume and center of mass of each unit;

[0020] S25, record the volume of each unit as , the center of mass is , the geometric feature information of the body is as follows:

[0021] Volume of the body V for:

[0022] ;

[0023] The center of mass of the body ( X , Y , Z )for:

[0024] ;

[0025] The moments of inertia of the bodies are:

[0026] ;

[0027] The moments of inertia of the bodies are:

[0028] .

[0029] Preferably, in step S24, the volume of the cubic unit is equal to a 3 , the center of mass is equal to the arithmetic mean of the coordinates of all vertices of the cube unit;

[0030] The equivalent unit is decomposed into at least one tetrahedron for calculation; the volume of the equivalent unit is equal to the sum of the volumes of the decomposed tetrahedrons; the center of mass of the equivalent unit is the weighted sum of the centers of mass of each tetrahedron after decomposition, and the weight of the center of mass of each tetrahedron is the ratio of the volume of the tetrahedron to the volume of the equivalent unit; the center of mass of the tetrahedron is equal to the arithmetic mean of the coordinates of all vertices of the tetrahedron.

[0031] Preferably, step S3 is specifically as follows:

[0032] S31, according to the disassembly result of step S2, obtaining the size information of all basic bodies in the final body reconstruction process, the external computational geometry feature information of all basic bodies, the external computational geometry feature information of all process bodies, the external computational geometry feature information of all final bodies, and Boolean operation information;

[0033] S32, creating all basic bodies in the finite element platform according to the size information of the basic bodies;

[0034] S33, based on the external computational geometry feature information and Boolean operation information of the basic body, the process body, and the final body obtained in step S31, select the corresponding body in the finite element platform through the external computational geometry feature information and perform Boolean operation to generate all the final bodies;

[0035] If the final body is directly formed from a basic body, the disassembly process of step S2 is not performed, and the created basic body is directly designated as the final body in step S3.

[0036] Preferably, selecting the corresponding body in the finite element platform by using the external calculated geometric feature information specifically means: first obtaining the external calculated geometric feature information of the body to be selected from step S2, then comparing the external calculated geometric feature information with the geometric feature information of all bodies read in the finite element platform, and selecting the body in the finite element platform whose geometric feature information has a difference with the external calculated geometric feature information that is less than a set error;

[0037] The corresponding body is selected by externally calculating geometric feature information, specifically using one or more of volume, center of mass, moment of inertia, and product of inertia.

[0038] Preferably, in step S4, if the contact between the final bodies is a bound contact between surfaces, a shared surface is established at the position where the final bodies contact each other, and the bound contact is replaced by the shared surface;

[0039] The shared surface satisfies the requirement that all finite element mesh nodes located on the shared surface during finite element mesh division are shared mesh nodes of the finite element mesh in the final volume on both sides of the shared surface.

[0040] Preferably, the base body includes: a polyhedron, a cylinder, a frustum, a sphere, an ellipsoid, a cone and a body obtained by stretching a base surface; the base surface includes a plane polygon, a circle and an ellipse; the stretching path is a line segment or a polyline.

[0041] Preferably, the model is a model of a composite foundation of a road; the final body includes a pile body, a post-construction stratum, an embankment and a cushion layer; the contact information includes the friction contact between the pile body and the post-construction stratum, the binding contact between the post-construction stratum and the cushion layer, and the binding contact between the cushion layer and the embankment; the physical parameter information includes the material parameters required for finite element calculation.

[0042] Preferably, in step S2, the pile body and the post-construction stratum are dismantled;

[0043] The Boolean operation corresponding to the pile body is: Boolean operation of a pile body foundation body one minus a pile body foundation body two to obtain the pile body, which is a process body; then Boolean operation of a pile body combined with a pile cap to obtain the pile body;

[0044] The Boolean operation corresponding to the post-construction stratum is: a Boolean operation of a pre-construction stratum is subtracted by n piles to obtain the post-construction stratum; wherein n>1.

[0045] The present invention also provides a computer program product, which includes a computer program / instruction, which, when executed by a processor, implements the method for automatically reconstructing a complex BIM in a finite element platform.

[0046] The advantages of the present invention are:

[0047] (1) The present invention realizes the automatic reconstruction of geometry, automatic establishment of contacts and automatic assignment of attributes of BIM models in the finite element platform. On this basis, the present invention can continue to use the built-in parametric language related to the finite element platform to realize automatic mesh division and automatic calculation, thereby truly realizing the finite element calculation of the BIM model, improving the calculation efficiency of the BIM model scheme, and having important significance for promoting the forward design of BIM.

[0048] (2) During the automatic operation of the finite element platform, the geometric feature information of various external calculations, including volume, center of mass, moment of inertia and product of inertia, is compared with the geometric feature information of the body in the finite element platform to select the corresponding body for operation, effectively ensuring the accuracy of the platform's automatic body selection.

[0049] (3) The final body is accurately selected through external computational geometric feature information, and contact settings and attribute assignments are performed on it, which solves the problem of the final body properties (collection properties, material properties, etc.) being lost after the Boolean operation of the finite element platform, resulting in the inability to calculate.

[0050] (4) The body is uniquely identified by combining multiple geometric feature attributes. This method abandons the traditional external identification method of adding attributes or numbers to the body, and provides a reference idea for the transmission and reconstruction of model data between other types of platforms. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Flowchart automatically reconstructed for BIM in the finite element platform.

[0052] Figure 2 This is a schematic diagram of the final body of this embodiment.

[0053] Figure 3 This is a schematic diagram of the foundation body being combined into a pile body in this embodiment.

[0054] Figure 4 This is a schematic diagram of the stratum after the combined construction of the foundation body in this embodiment.

[0055] Figure 5 Generate schematic diagrams for generation units.

[0056] The reference numerals are as follows:

[0057] 1. Edge intersection point; 2. Intersecting edges; 3. Fitting plane; 4. Pile foundation body 1; 5. Pile foundation body 2; 6. Pile body; 7. Pile cap; 8. Pile body; 9. Stratum before construction; 10. Pile group; 11. Stratum after construction; 12. Embankment; 13. Pad layer. DETAILED DESCRIPTION

[0058] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0059] Depend on Figure 1 As shown, a method for automatically reconstructing a complex BIM in a finite element platform includes the following steps:

[0060] S1, obtain the geometric size information, spatial position information, physical parameter information and contact information of all final bodies in the model in the BIM platform.

[0061] The final body refers to a geometric body that is continuous in space and has the same physical parameter information.

[0062] like Figure 2-Figure 4 As shown, in this embodiment, the model that needs to be reconstructed in the ANSYS platform (finite element analysis and engineering simulation platform) is a model of a road composite foundation. The final bodies of the model include: pile body 8, post-construction stratum 11, embankment 12 and cushion layer 13.

[0063] The contact information includes the friction contact between the pile body 8 and the post-construction ground layer 11 , the binding contact between the post-construction ground layer 11 and the cushion layer 13 , and the binding contact between the cushion layer 13 and the embankment 12 .

[0064] The physical parameter information refers to all material parameters required for finite element calculations. The material parameters required for finite element calculations are related to the calculation objectives. In this embodiment, the finite element calculation of the composite road foundation requires settlement and stability results. Therefore, the physical parameter information that needs to be read by the BIM platform includes density, elastic modulus, Poisson's ratio, cohesion, and internal friction angle.

[0065] S2, according to the geometric size information of the final body, disassemble the final body to obtain the Boolean operation of forming the final body from the basic body, record the corresponding Boolean operation, and calculate and obtain the geometric feature information of the basic body, process body and final body, which is recorded as external calculated geometric feature information.

[0066] The base body refers to a geometric body directly generated by given parameters in the finite element platform. The base bodies include polyhedrons, cylinders, frustums, spheres, ellipsoids, cones, and bodies derived from extrusion of base surfaces. The base surfaces include planar polygons, circles, and ellipses. The extrusion path can be a line segment or a polyline. Furthermore, if a base body derived from extrusion is obtained in the BIM platform, and the extrusion path is not a polyline, a polyline approximation is used instead.

[0067] The procedural body refers to a geometric body that has been subjected to at least one Boolean operation on a basic body but has not yet formed a final body.

[0068] The Boolean operations include Boolean subtraction, Boolean union, and Boolean intersection, which respectively refer to subtraction, union, and intersection between bodies (basic bodies, process bodies, or final bodies).

[0069] The geometric feature information includes volume, center of mass, moment of inertia and product of inertia.

[0070] like Figure 3 and Figure 4 As shown, the pile body 8 and the post-construction stratum 11 can be disassembled.

[0071] The Boolean operation for pile body 8 is as follows: Subtract pile body foundation 1 4 from pile body foundation 2 5 to obtain pile body 6 (process body); then, combine pile body 6 with pile cap 7 through Boolean operation to obtain pile body 8. Pile body foundation 1 4 and pile body foundation 2 5 are cylinders with different diameters.

[0072] The Boolean operation of the post-construction stratum 11 is: subtract eight pile bodies 8 from one pre-construction stratum 9 by Boolean operation to obtain the post-construction stratum 11 , wherein the eight pile bodies 8 constitute a pile group 10 .

[0073] Figure 3 and Figure 4 The "+" in the expression represents the Boolean operation of union, and the "-" represents the Boolean operation of subtraction.

[0074] In step S2, the geometric feature information of the basic body, the process body, and the final body is calculated as follows:

[0075] S21, set three groups of dividing surfaces in space, each dividing surface in each group is parallel to each other and arranged at equal intervals, and the dividing surfaces in different groups are perpendicular to each other; the spacing is a .

[0076] S22, using three sets of splitting faces to split the body (basic body, process body or final body) into multiple volumes no larger than a 3 The unit of ; where the volume is equal to a 3The unit with a volume smaller than a 3 The unit is called an isochronous unit.

[0077] S23, converting the equal-generation unit into a polyhedron by equal-generation replacement; the equal-generation replacement means replacing the faces in the equal-generation unit that do not coincide with the dividing surface with a fitting plane 3; the fitting replacement satisfies that the sum of the squares of the projection distances of all edge intersection points 1 onto the fitting plane 3 is minimized; the edge intersection point 1 refers to the intersection of the face in the equal-generation unit that does not coincide with the dividing surface and the intersecting edge 2; the intersecting edge 2 refers to the intersection line formed by the intersection of all dividing surfaces.

[0078] like Figure 5 As shown, Figure 5 On the left is the equivalent unit (the volume is smaller than a 3 ), there is a non-coincident surface with the split surface, and there are four edge intersection points 1 with the intersecting edge 2. Figure 5 The sum of the squares of the projection distances of the four edge intersection points 1 on the right side to the fitting plane 3 is the smallest.

[0079] S24, calculate the volume and center of mass of each unit.

[0080] The volume of the cubic unit is equal to a 3 , the center of mass is equal to the arithmetic mean of the coordinates of all vertices of the cube unit.

[0081] The equivalent unit is decomposed into no less than one tetrahedron (triangular pyramid) for calculation; the volume of the equivalent unit is equal to the sum of the volumes of the decomposed tetrahedrons; the center of mass of the equivalent unit is the weighted sum of the centers of mass of each tetrahedron after decomposition, and the weight of the center of mass of each tetrahedron is the ratio of the volume of the tetrahedron to the volume of the equivalent unit; the center of mass of the tetrahedron is equal to the arithmetic mean of the coordinates of all vertices of the tetrahedron.

[0082] S25, record the volume of each unit as , the centroid coordinates are , the geometric feature information of the body (basic body, process body or final body) is as follows:

[0083] Volume of the body V for:

[0084] ;

[0085] The center of mass of the body ( X , Y , Z )for:

[0086] ;

[0087] The moments of inertia of the bodies are:

[0088] ;

[0089] The moments of inertia of the bodies are:

[0090] .

[0091] S3, reconstructing the final body in the finite element platform according to the Boolean operations and external computational geometry feature information obtained by disassembling the final body.

[0092] Step S3 is specifically as follows:

[0093] S31, according to the disassembly result of step S2, obtain the size information of all basic bodies in the final body reconstruction process, the external computational geometry feature information of all basic bodies, the external computational geometry feature information of all process bodies, the external computational geometry feature information of all final bodies and Boolean operation information.

[0094] S32, create all basic bodies in the ANSYS platform (finite element platform) according to the size information of the basic bodies.

[0095] In this embodiment, Figure 3 As shown in the figure, the process and APDL code for creating all the foundation bodies involved in generating pile body 8 (including pile foundation body 1 4, pile foundation body 2 5 and pile cap 7) in the ANSYS platform are as follows:

[0096] Assume that the three-dimensional coordinates of the center point P1 of the top surface of the pile cap 7 in the pile body 8 are (X1, Y1, Z1), and then define the three-dimensional coordinates of point P2 as (X1+1, Y1, Z1) and the three-dimensional coordinates of point P3 as (X1, Y1+1, Z1); first use the KWPLAN instruction to move the origin of the working coordinate system to P1, and make point P2 located on the X-axis of the working coordinate system, point P3 located on the Y-axis of the working coordinate system, and the Z-axis direction satisfies the right-hand screw rule; the corresponding APDL code is: KWPLAN, P1, P2, P3.

[0097] The diameter of the pile foundation body 1 4 is D1 and the length is H1; the diameter of the pile foundation body 2 5 is D2 and the length is H1; the length of the pile cap 7 in the X-axis direction is L1, the width in the Y-axis direction is B1, and the height in the Z-axis direction is H2.

[0098] In the above working coordinate system, use the cylinder creation command CYLIND to create a pile foundation body 4 with a radius of D1 / 2, a top surface Z-axis coordinate value of -H2, and a bottom surface Z-axis coordinate value of -H1-H2; the corresponding APDL code is: CYLIND, D1 / 2, -H2, -H1-H2.

[0099] Then use the cylinder creation command CYLIND to create pile foundation body 25 with a radius of D / 2, a top surface Z-axis coordinate value of -H2, and a bottom surface Z-axis coordinate value of -H1-H2; the corresponding APDL code is: CYLIND, D2 / 2, -H2, -H1-H2.

[0100] Then use the block creation command BLOCK to create pile cap 7 with an X-axis range of [-L1 / 2, L1 / 2], a Y-axis range of [-B1 / 2, B1 / 2], and a Z-axis range of [-H2, 0]; the corresponding APDL code is: BLOCK, -L1 / 2, L1 / 2, -B1 / 2, B1 / 2, -H2, 0.

[0101] S33, based on the external computational geometry feature information and Boolean operation information of the basic body, process body and final body obtained in step S31, select the corresponding body on the ANSYS platform through the external computational geometry feature information to perform Boolean operation and generate all final bodies.

[0102] by Figure 3 For example, the specific execution process of step S33 is as follows:

[0103] S331, first, in the ANSYS platform, the external computational geometry feature information of the pile foundation body 1 4, pile foundation body 2 5, pile body 6 and pile cap 7 involved in the pile body 8 is defined and generated through APDL code, which is recorded as the external computational geometry feature information set.

[0104] S332, traverse the geometric feature information of all bodies in the ANSYS platform through the VSUM command of the APDL code, compare the geometric feature information of the body obtained by the VSUM command with the geometric feature information in the external calculation geometric feature information set, find and select the body with the same external calculation geometric feature information as the pile body foundation body 1 4, then find and select the body with the same external calculation geometric feature information as the pile body foundation body 2 5, use the Boolean operation of the body with the same external calculation geometric feature information as the pile body foundation body 1 4 to subtract the body with the same external calculation geometric feature information as the pile body foundation body 2 5; at this time, the process body pile body 6 can be formed in the ANSYS platform.

[0105] S333, traverse the geometric feature information of all bodies in the ANSYS platform through the VSUM command of the APDL code, compare the geometric feature information of the body obtained by the VSUM command with the geometric feature information in the external calculation geometric feature information set, find and select the body with the same external calculation geometric feature information as the pile body 6, then find and select the body with the same external calculation geometric feature information as the pile cap 7, and use the Boolean operation of the body with the same external calculation geometric feature information as the pile body 6 to combine the body with the same external calculation geometric feature information as the pile cap 7; at this time, the final pile body 8 can be formed in the ANSYS platform.

[0106] Furthermore, if the final body is directly formed from a basic body, there is no need to perform the disassembly step in step S2 , and the basic body is directly designated as the final body in step S3 .

[0107] Furthermore, during the reconstruction of the final body, other final bodies may be added to the Boolean operation process to form the final body.

[0108] For example, after construction, the ground layer 11 requires piles 8 to perform Boolean operations.

[0109] Furthermore, the corresponding body is selected through external computational geometric feature information, which specifically means: first obtaining the external computational geometric feature information of the body to be selected from step S2, then comparing the external computational geometric feature information with the geometric feature information of all bodies read in the finite element platform, and selecting the body in the finite element platform whose geometric feature information has a difference with the external computational geometric feature information that is less than a set error; the error is a manually set parameter.

[0110] The corresponding body is selected by externally calculating geometric feature information, specifically, one or more of volume, center of mass, moment of inertia and product of inertia can be used.

[0111] S4: Based on the external computational geometry information of the final bodies, corresponding final bodies are selected to establish contact and assigned corresponding physical parameter information. Furthermore, if the contact between the final bodies is surface-to-surface bound contact, a coupling operation is used to establish shared surfaces at the locations where the final bodies contact each other, and the shared surfaces replace the bound contact.

[0112] The shared surface satisfies the requirement that all finite element mesh nodes located on the shared surface during finite element mesh division are shared mesh nodes of the finite element mesh in the final volume on both sides of the shared surface.

[0113] like Figure 2 As shown in the figure, the contact type between the embankment 12 and the cushion layer 13 is usually defined as surface-to-surface bound contact in actual calculations. Considering that too much contact in the model may easily lead to non-convergence of the calculation, the area where the bottom surface of the embankment 12 and the top surface of the cushion layer 13 contact can be set as a shared surface. The specific operation process is as follows:

[0114] The embankment 12 and the cushion layer 13 are selected by external computational geometric feature information, and the contact area between the two bodies is set as a shared surface by the VGLUE command; the selection by external computational geometric feature information here is consistent with the selection by external computational geometric feature information in S33.

[0115] Because the operating principle of the VGLUE command in the ANSYS platform is consistent with Boolean operations, the body after the VGLUE command operation needs to be selected through external computational geometry feature information and assigned corresponding material properties.

[0116] This embodiment implements APDL command stream operations for geometric reconstruction, attribute assignment, and contact setting of composite foundation models in the finite element platform. Combined with ANSYS APDL's element type definition, meshing, and computational solution command streams, this command stream enables automatic reconstruction and analysis of composite foundation models in the ANSYS platform. In actual operation, secondary development of the BIM platform is sufficient to synchronously generate the corresponding APDL command stream file upon obtaining model information required for finite element calculations. This command stream file can then be read by calling the ANSYS platform in the background to achieve automated analysis of this type of project.

[0117] Similarly, a finite element platform that can support the entire process of the present invention in terms of secondary development capabilities can also achieve this effect.

[0118] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for automatically reconstructing complex BIM in a finite element platform, characterized in that: The following steps are involved: S1, obtain the geometric size information, spatial position information, physical parameter information and contact information of all final bodies in the model in the BIM platform; The final body refers to a geometric body that is continuous in space and has the same physical parameter information; S2, disassemble the final body, obtain the Boolean operation of forming the final body from the basic body, record the corresponding Boolean operation, and obtain the geometric feature information of the basic body, the process body and the final body, which is recorded as the external calculated geometric feature information; The basic body refers to a geometric body directly generated by given parameters in the finite element platform; The process body refers to a geometric body that has undergone at least one Boolean operation on the basic body but has not yet formed a final body; The geometric feature information includes volume, center of mass, moment of inertia and product of inertia; S3, based on the Boolean operation obtained by disassembling the final body and the external computational geometry feature information, the corresponding body is selected in the finite element platform to perform the Boolean operation and reconstruct the final body; S4, selecting the corresponding final body to establish contact based on the external computational geometric feature information, and assigning corresponding physical parameter information to the final body; In step S2, the external geometric feature information of the basic body, the process body and the final body is calculated in the following manner: S21, set three groups of dividing surfaces in space, each dividing surface in each group is parallel to each other and arranged at equal intervals, and the dividing surfaces in different groups are perpendicular to each other; the spacing is a ; S22, using three sets of dividing faces to divide the body into multiple volumes no larger than a 3 The unit of ; where the volume is equal to a 3 The unit with a volume smaller than a 3 The unit is called an equivalent unit; the body refers to the basic body, process body or final body; S23, converting the equal generation unit into a polyhedron by equal generation replacement; the equal generation replacement means replacing the faces in the equal generation unit that do not coincide with the dividing surface with a fitting plane (3); the fitting replacement satisfies that the sum of the squares of the projection distances of all edge intersection points (1) onto the fitting plane (3) is minimum; the edge intersection point (1) refers to the intersection point of the faces in the equal generation unit that do not coincide with the dividing surface and the intersecting edge (2); the intersecting edge (2) refers to the intersection line formed by the intersection of all the dividing surfaces; S24, calculate the volume and center of mass of each unit; S25, record the volume of each unit as , the center of mass is , the geometric feature information of the body is as follows: Volume of the body V for: ; The center of mass of the body ( X , Y , Z )for: ; The moments of inertia of the bodies are: ; The moments of inertia of the bodies are: .

2. The method for automatically reconstructing a complex BIM in a finite element platform according to claim 1, characterized in that: In step S24, the volume of the cubic unit is equal to a 3 , the center of mass is equal to the arithmetic mean of the coordinates of all vertices of the cube unit; Decompose the equivalent unit into at least one tetrahedron for calculation; the volume of the equivalent unit is equal to the sum of the volumes of the decomposed tetrahedrons; The centroid of the equivalent unit is the weighted sum of the centroids of each tetrahedron after decomposition, and the weight of each tetrahedron centroid is the ratio of the volume of the tetrahedron to the volume of the equivalent unit; the tetrahedron centroid is equal to the arithmetic mean of the coordinates of all vertices of the tetrahedron.

3. The method for automatically reconstructing a complex BIM in a finite element platform according to claim 1, characterized in that: Step S3 is specifically as follows: S31, according to the disassembly result of step S2, obtaining the size information of all basic bodies in the final body reconstruction process, the external computational geometry feature information of all basic bodies, the external computational geometry feature information of all process bodies, the external computational geometry feature information of all final bodies, and Boolean operation information; S32, creating all basic bodies in the finite element platform according to the size information of the basic bodies; S33, based on the external computational geometry feature information and Boolean operation information of the basic body, the process body, and the final body obtained in step S31, select the corresponding body in the finite element platform through the external computational geometry feature information and perform Boolean operation to generate all the final bodies; If the final body is directly formed from a basic body, the disassembly process of step S2 is not performed, and the created basic body is directly designated as the final body in step S3.

4. The method for automatically reconstructing a complex BIM in a finite element platform according to claim 1 or 3, characterized in that: Selecting a corresponding body in the finite element platform by using the external calculated geometric feature information specifically includes: first obtaining the external calculated geometric feature information of the body to be selected from step S2, then comparing the external calculated geometric feature information with the geometric feature information of all bodies read in the finite element platform, and selecting a body in the finite element platform whose geometric feature information has a difference with the external calculated geometric feature information that is less than a set error; The corresponding body is selected by externally calculating geometric feature information, specifically using one or more of volume, center of mass, moment of inertia, and product of inertia.

5. The method for automatically reconstructing a complex BIM in a finite element platform according to claim 1, characterized in that: In step S4, if the contact between the final bodies is a bound contact between surfaces, a shared surface is created at the position where the final bodies contact each other, and the bound contact is replaced by the shared surface; The shared surface satisfies the requirement that all finite element mesh nodes located on the shared surface during finite element mesh division are shared mesh nodes of the finite element mesh in the final volume on both sides of the shared surface.

6. The method for automatically reconstructing a complex BIM in a finite element platform according to claim 1, characterized in that: The model is a model of a composite foundation of a road; the final body includes a pile body (8), a post-construction stratum (11), an embankment (12) and a cushion layer (13); the contact information includes friction contact between the pile body (8) and the post-construction stratum (11), binding contact between the post-construction stratum (11) and the cushion layer (13), and binding contact between the cushion layer (13) and the embankment (12); and the physical parameter information includes material parameters required for finite element calculation.

7. The method for automatically reconstructing a complex BIM in a finite element platform according to claim 6, characterized in that: In step S2, the pile body (8) and the post-construction stratum (11) are dismantled; The Boolean operation corresponding to the pile body (8) is: Boolean operation of a pile body foundation body 1 (4) minus a pile body foundation body 2 (5) to obtain a pile body (6), wherein the pile body (6) is a process body; and then Boolean operation of a pile body (6) is combined with a pile cap (7) to obtain a pile body (8); The Boolean operation corresponding to the post-construction stratum (11) is: a Boolean operation of a pre-construction stratum (9) is subtracted by n pile bodies (8) to obtain the post-construction stratum (11); wherein n>1.

8. A computer program product, characterized in that It includes a computer program / instruction, which, when executed by a processor, implements a method for automatically reconstructing a complex BIM in a finite element platform as described in any one of claims 1 to 6.

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