CN115310171A - Grasshopper-based space string structure parametric modeling method - Google Patents

Abstract

The invention discloses a grasshopper-based parametric modeling method for a space string structure, which comprises the following steps: picking up a three-dimensional model of a building surface skin of a string structure to be built; determining a structure type and geometric control parameters, and calling input parameters of an input arithmetic unit; and calling the packed beam string frame model generation arithmetic unit or the beam string frame model generation arithmetic unit based on the input parameters to obtain a beam string structure three-dimensional wire frame model. The invention can quickly establish the three-dimensional model of the string structure according to the building surface, can freely control the structure type and the geometric parameters, has simple and efficient design method, and provides great convenience for the structure modeling, scheme comparison, computational analysis and optimization design of the space string structure.

Description

Spatial string structure parametric modeling method based on grasshopper

Technical Field

The invention belongs to the field of computer-aided structure design, is particularly applied to parametric drive generation of a space string structure, and is a general parametric modeling implementation method for the space string structure based on a Rhino platform through a Grasshopper visual programming technology.

Background

In recent years, with the rapid improvement of the building level of China, the application of the string-stretching structure can be seen in various stadiums, transportation hub station houses and roofs of industrial factory buildings, the string-stretching structure is a hybrid structure, has the characteristics of rigidity and flexibility, is clear in stress mode, greatly exerts the characteristics of materials, is attractive in appearance, and is gradually increased in application in large-span structures.

In the structural modeling stage, in the prior art, in the case of a flat roof and a sloping roof, a designer can draw a string structure wire frame model step by step in drawing software such as CAD (computer-aided design) and the like in a traditional design mode, and although the time is long, the process can be finished; however, when the structural surface is a curved surface, even the curvature of the curved surface is inconsistent and can be followed without regularity, the traditional design method is difficult to carry out. In the structure calculation stage, the situations that the structure calculation result is unreasonable, the bearing capacity is too large or too small, and the structure model needs to be adjusted again often occur, or the building scheme needs to be adjusted, so that designers need to come again. Therefore, the conventional design method has the disadvantages of extremely low efficiency, long time consumption and the like, and a parametric design method is urgently needed.

The invention applies parameterization as a main design method to the modeling work flow of the space string structure, can build a structural model by adhering to the building surface, and solves the problem that the traditional modeling surface cannot model irregular curved surfaces; meanwhile, the structure type and the geometric control parameters can be freely controlled, and a structure wire frame model can be generated immediately after the parameters are defined for subsequent scheme comparison and structural calculation analysis. The invention can greatly improve the working efficiency of designers, optimize the design quality of projects, improve the industry competitiveness of teams and reduce the labor and time cost of design units.

Disclosure of Invention

The invention aims to solve the problem of providing a parameterized modeling method of a space string structure, which is based on a grasshopper program in a three-dimensional modeling software of a Rhino, utilizes the grasshopper program to program a battery pack program module, adjusts self-defined input parameters, operates the module to quickly output a string structure wire frame model, and the wire frame model can be directly introduced into a structure analysis software and then can be subjected to subsequent deepened design.

The invention adopts the following technical scheme: a spatial string structure parameterization modeling method based on grasshopper comprises the following steps: picking up a building surface three-dimensional model of a string structure to be built; determining a structure type and geometric control parameters, and calling input parameters of an input arithmetic unit; and calling the packed beam string frame model generation arithmetic unit or the beam string frame model generation arithmetic unit based on the input geometric and type parameters to obtain the beam string structure three-dimensional wire frame model.

The method for generating the three-dimensional wire frame model of the beam string structure by the beam string wire frame model generation arithmetic unit comprises the following steps: enabling the building surface S1 to move downwards for a corresponding distance according to the input back distance parameter to obtain a structural surface S2, decomposing the structural surface S2 to obtain structural side lines, and comparing to obtain two long-span side lines L1 and L2; equally dividing the long-span two side lines L1 and L2 according to the input parameter longitudinal segmentation number to obtain a point list [ P1], a point list [ P2], and turning the point list [ P2] to obtain a point list [ P3]; establishing a catenary line [ L3] between the point list [ P1] and the point list [ P3], wherein the sag of the catenary line is determined according to an input value; connecting the point list [ P1] and the point list [ P3] to obtain a line list [ L4], and equally dividing line segments in the line list [ L4] according to the input parameter transverse segmentation number to obtain a dot matrix [ P4]; making a ray along points in the lattice [ P4] to intersect with the structural surface S2 to obtain an upper chord node lattice [ P5], and intersecting with the linear array [ L3] to obtain a lower chord node lattice [ P6]; the upper chord node lattice [ P5] is connected with itself to obtain an upper chord beam linear array [ X1], the lower chord node lattice [ P6] is connected with itself to obtain a lower chord cable linear array [ X2], the upper chord node lattice [ P5] is connected with the lower chord node lattice [ P6] to obtain an intermediate strut linear array [ X3], the upper chord node lattice [ P5] is subjected to matrix transposition and then connected with itself to obtain a purlin linear array [ X4], and the upper chord beam linear array [ X1], the lower chord cable linear array [ X2], the intermediate strut linear array [ X3] and the purlin linear array [ X4] are integrated to obtain a final beam structure three-dimensional wire frame model [ X ].

The method for generating the three-dimensional wireframe model of the truss string structure by the truss string wireframe model generation arithmetic unit comprises the following steps: enabling the building surface to move downwards for a corresponding distance according to the input back distance parameter by the building surface S1 to obtain a structural surface S2, decomposing the structural surface S2 to obtain structural side lines, and comparing to obtain two long-span side lines L1 and L2; cutting off a line segment with the length of d at one end of each of two long-span sidelines L1 and L2, wherein d is the transverse distance of an input parameter, then equally dividing according to the number of longitudinal sections of the input parameter to obtain two dot matrixes, and connecting the two dot matrixes to obtain a group of [ L3] in an upper chord line frame model of the inverted triangular three-dimensional truss; after d is cut off from the other ends of the two long-span sidelines L1 and L2, repeating the previous step to obtain another group [ L4] of the upper chord wire frame model of the inverted triangular three-dimensional truss; cutting off line segments with the length of d/2 from both ends of two side lines L1 and L2 of the long span, repeating the previous step to obtain a line set [ L5], vertically translating the line in [ L5] by h, taking the value of h as the height of an input parameter truss, cutting off the line segment with the length of L/2 from both ends, wherein the value of L is equal to the length of the line segment in [ L5] divided by n, and taking n as the number of input parameter transverse segments to obtain a lower chord set [ L6] of the inverted triangular three-dimensional truss; respectively equally dividing [ L3] and [ L4] into n sections to obtain a dot matrix [ P1], [ P2], equally dividing a line group [ L6] into n-1 sections to obtain a dot matrix [ P3]; grouping and connecting points in the dot matrix [ P1] [ P2] [ P3] according to different combinations to obtain a diagonal web member line group, an upper chord tie rod line group and a purline line group, finally integrating the diagonal web member line group, the upper chord tie rod line group and the purline line group to obtain an integral line frame model [ X1] of the inverted triangular three-dimensional truss, establishing a catenary line through a line group [ L6], intersecting the catenary line with a ray passing through the dot matrix [ P3] according to input parameters to obtain a dot matrix [ P4] of the cord nodes, connecting the dot matrix [ P3] with the dot matrix [ P4] to obtain a strut line group [ X2], and connecting the dot matrix [ P4] to obtain a cord line group [ X3]; and finally, integrating the wire group [ X1] [ X2] [ X3] to obtain a final truss string structure three-dimensional wire frame model [ X ].

The structure types of the invention comprise a beam string structure and a beam string truss structure; the geometric control parameters comprise the number of transverse sections, the number of longitudinal sections, the height of the truss, the cable sag, the transverse spacing and the back-off distance; and fitting the building modeling surface to generate a string-structure three-dimensional wire frame model according to the characteristics of the building modeling through variable design parameters.

Based on the grasshopper program in the three-dimensional modeling software, the battery pack program module is compiled by using the grasshopper program, the user-defined input parameters are adjusted, the module is operated to quickly output the wire frame model with the string structure, and the wire frame model can be directly introduced into the structure analysis software and then can be subjected to subsequent deepened design. The invention can quickly establish the three-dimensional model of the string structure according to the building surface, can freely control the structure type and the geometric parameters, has simple and efficient design method, and provides great convenience for the structure modeling, scheme comparison, computational analysis and optimization design of the space string structure.

Drawings

FIG. 1 is a flow chart of the parametric design method for string structure of the present invention;

FIG. 2 is a string structure cluster program group according to the present invention;

FIG. 3 is a schematic diagram illustrating the structure of beam string structure according to the present invention;

fig. 4 is a schematic diagram of the generation of the truss-string structure of the present invention.

Detailed Description

The invention comprises the following steps: based on the grasshopper program in the three-dimensional modeling software, a battery pack program module is compiled by using the grasshopper program, the user-defined input parameters are adjusted, the module is operated to quickly output a string structure wire frame model, the wire frame model can be directly introduced into the structure analysis software, and then the subsequent deepened design can be carried out:

1. specifying an architectural skin for generating a structural model;

2. and selecting a structure type, defining the geometric parameters of the structure, and finishing the definition of the parameters of the input end. The input parameters include:

number of horizontal segments: for determining a member length in a span direction;

number of longitudinal segments: for determining a component spacing in a vertical span direction;

truss height: the truss height of the truss string is defined, and the truss string structure is invalid;

rope sag: defining the sag of the lower cable;

the structure type is as follows: the beam string structure or the truss string structure can be selected;

transverse spacing: defining the distance between two upper chord members of the truss string structure, and having no effect on the truss string structure;

building surface: for specifying building skins;

back distance: the distance between the structure control point and the packaging surface is input according to the packaging modeling material.

3. The core computing battery set is organized into a cluster, and a computing kernel of the core computing battery set comprises two parts, namely a truss string wire frame model generating arithmetic unit and a truss string wire frame model generating arithmetic unit. After the parameters are defined in the previous steps, the cluster group arithmetic unit carries out operation and directly outputs the required string structure wire frame model.

3.1 the method for generating the three-dimensional wire frame model of the beam string structure by the beam string wire frame model generation arithmetic unit comprises the following steps: enabling the building surface to move downwards for a corresponding distance according to the input back distance parameter by the building surface S1 to obtain a structural surface S2, decomposing the structural surface S2 to obtain structural side lines, and comparing to obtain two long-span side lines L1 and L2; equally dividing the long-span two side lines L1 and L2 according to the input parameter longitudinal segmentation number to obtain a point list [ P1], a point list [ P2], and turning the point list [ P2] to obtain a point list [ P3]; establishing a catenary line [ L3] between the point list [ P1] and the point list [ P3], wherein the sag of the catenary line is determined according to an input value; connecting the point list [ P1] with the point list [ P3] to obtain a line list [ L4], and equally dividing line segments in the line list [ L4] according to the input parameter transverse segmentation number to obtain a dot matrix [ P4]; making a ray along points in the lattice [ P4] to intersect with the structural surface S2 to obtain an upper chord node lattice [ P5], and intersecting with the linear array [ L3] to obtain a lower chord node lattice [ P6]; the upper chord node lattice [ P5] is connected with itself to obtain an upper chord beam linear array [ X1], the lower chord node lattice [ P6] is connected with itself to obtain a lower chord cable linear array [ X2], the upper chord node lattice [ P5] is connected with the lower chord node lattice [ P6] to obtain an intermediate strut linear array [ X3], the upper chord node lattice [ P5] is subjected to matrix transposition and then connected with itself to obtain a purlin linear array [ X4], and the upper chord beam linear array [ X1], the lower chord cable linear array [ X2], the intermediate strut linear array [ X3] and the purlin linear array [ X4] are integrated to obtain a final beam structure three-dimensional wire frame model [ X ].

3.2 the method for generating the three-dimensional wire frame model of the truss string structure by the truss string wire frame model generating arithmetic unit comprises the following steps: enabling the building surface S1 to move downwards for a corresponding distance according to the input back distance parameter to obtain a structural surface S2, decomposing the structural surface S2 to obtain structural side lines, and comparing to obtain two long-span side lines L1 and L2; cutting off a line segment with the length of d at one end of each of two long-span sidelines L1 and L2, wherein d is the transverse distance of an input parameter, then equally dividing according to the number of longitudinal sections of the input parameter to obtain two dot matrixes, and connecting the two dot matrixes to obtain a group of [ L3] in an upper chord line frame model of the inverted triangular three-dimensional truss; d, cutting off the other ends of the two long-span side lines L1 and L2, and repeating the previous step to obtain another group [ L4] in the upper chord wire frame model of the inverted triangular three-dimensional truss; cutting off line segments with the length of d/2 from both ends of two side lines L1 and L2 of the long span, repeating the previous step to obtain a line set [ L5], vertically translating the line in [ L5] by h, taking the value of h as the height of an input parameter truss, cutting off the line segment with the length of L/2 from both ends, wherein the value of L is equal to the length of the line segment in [ L5] divided by n, and taking n as the number of input parameter transverse segments to obtain a lower chord set [ L6] of the inverted triangular three-dimensional truss; respectively equally dividing [ L3] and [ L4] into n sections to obtain a dot matrix [ P1], [ P2], equally dividing a line group [ L6] into n-1 sections to obtain a dot matrix [ P3]; grouping and connecting points in the dot matrix [ P1] [ P2] [ P3] according to different combinations to obtain a diagonal web member line group, an upper chord tie rod line group and a purline line group, finally integrating the diagonal web member line group, the upper chord tie rod line group and the purline line group to obtain an integral line frame model [ X1] of the inverted triangular three-dimensional truss, establishing a catenary line through a line group [ L6], intersecting the catenary line with a ray passing through the dot matrix [ P3] according to input parameters to obtain a dot matrix [ P4] of the cord nodes, connecting the dot matrix [ P3] with the dot matrix [ P4] to obtain a strut line group [ X2], and connecting the dot matrix [ P4] to obtain a cord line group [ X3]; and finally, integrating the wire group [ X1] [ X2] [ X3] to obtain a final truss string structure three-dimensional wire frame model [ X ].

4. After the wire frame model of the string structure is obtained, structural analysis software such as Midas can be imported for subsequent deepened design.

The invention is further described with reference to the accompanying drawings.

As shown in fig. 1, the parametric design method of the string structure is composed of three processes of extraction of a building surface, input of control parameters, and derivation and calculation. The system comprises eight parameterization process modules, and can contain a whole set of structural design process from structural modeling to analytical design of the string structure. When the technology is used, the structural geometric parameters can be used as control variables, and the structural model is comprehensively designed and optimized by modifying and debugging the parameters and combining the calculation result.

As shown in fig. 2, the program in the parametric design platform is shown, including the control battery packs and the cluster operator at the input. After the preposed input parameters are defined, the arithmetic unit can calculate and output a wire frame model for structural design. The process comprises the following steps:

1. designating a building surface for generating a structure;

2. selecting structure types including a beam string structure and a truss string structure;

3. inputting structural geometric parameters including the number of transverse sections, the number of longitudinal sections, the height of the truss, the cable sag, the transverse spacing and the back-off distance;

and 4. Performing operation by the cluster operator and outputting the wire frame model.

When the selected structure type is a beam string structure, the operation steps are as follows: backing to obtain a structural surface; according to the long-span two side lines of the structural surface, equally dividing and connecting the lines, and equally dividing the lines; then, obtaining an upper chord beam node and a lower chord cable node through projection; and finally, connecting all the nodes to obtain a three-dimensional wire frame model of the beam string structure. As shown in fig. 3, which is a schematic diagram of a certain chord beam wire frame model generated.

When the selected structure type is a truss string structure, the operation steps are as follows: backing to obtain a structural surface; according to the two long-span side lines of the structural surface, different cutting, equal division and connection processing are carried out, and the upper chord and the lower chord of the truss can be obtained; grouping and connecting points on the chord members according to different combinations to obtain an inclined web member line group, an upper chord tie rod line group and a purline line group; projecting to the catenary through the lower chord node to obtain a cable node, and further obtaining a stay bar and a cable group of the cable; and finally, integrating all the groups of wire frames to obtain a final three-dimensional wire frame model of the truss string structure. As shown in fig. 4, which is a schematic diagram of a certain truss wire frame model generated.

Claims (4)

1. A spatial string structure parameterization modeling method based on grasshopper is characterized by comprising the following steps: picking up a building surface three-dimensional model of a string structure to be built; determining a structure type and geometric control parameters, and calling input parameters of an input arithmetic unit; and calling the packed beam string frame model generation arithmetic unit or the beam string frame model generation arithmetic unit based on the input geometric and type parameters to obtain the beam string structure three-dimensional wire frame model.

2. The method of claim 1, wherein the method for generating the three-dimensional wire frame model of the beam string structure by the beam string wire frame model generation arithmetic unit comprises the following steps: enabling the building surface S1 to move downwards for a corresponding distance according to the input back distance parameter to obtain a structural surface S2, decomposing the structural surface S2 to obtain structural side lines, and comparing to obtain two long-span side lines L1 and L2; equally dividing the long-span two side lines L1 and L2 according to the input parameter longitudinal segmentation number to obtain a point list [ P1], a point list [ P2], and turning the point list [ P2] to obtain a point list [ P3]; establishing a catenary [ L3] between the point list [ P1] and the point list [ P3], wherein the sag of the catenary is determined according to an input value; connecting the point list [ P1] with the point list [ P3] to obtain a line list [ L4], and equally dividing line segments in the line list [ L4] according to the input parameter transverse segmentation number to obtain a dot matrix [ P4]; making a ray along points in the lattice [ P4] to intersect with the structural surface S2 to obtain an upper chord node lattice [ P5], and intersecting with the linear array [ L3] to obtain a lower chord node lattice [ P6]; the upper chord node lattice [ P5] is connected with itself to obtain an upper chord beam linear array [ X1], the lower chord node lattice [ P6] is connected with itself to obtain a lower chord cable linear array [ X2], the upper chord node lattice [ P5] is connected with the lower chord node lattice [ P6] to obtain an intermediate strut linear array [ X3], the upper chord node lattice [ P5] is subjected to matrix transposition and then connected with itself to obtain a purlin linear array [ X4], and the upper chord beam linear array [ X1], the lower chord cable linear array [ X2], the intermediate strut linear array [ X3] and the purlin linear array [ X4] are integrated to obtain a final beam structure three-dimensional wire frame model [ X ].

3. The method of claim 1, wherein the method for generating the three-dimensional wire frame model of the truss-string structure by the truss-string wire frame model generation arithmetic unit comprises the following steps: enabling the building surface S1 to move downwards for a corresponding distance according to the input back distance parameter to obtain a structural surface S2, decomposing the structural surface S2 to obtain structural side lines, and comparing to obtain two long-span side lines L1 and L2; cutting off a line segment with the length of d at one end of each of two long-span sidelines L1 and L2, wherein d is the transverse distance of an input parameter, then equally dividing according to the number of longitudinal sections of the input parameter to obtain two dot matrixes, and connecting the two dot matrixes to obtain a group of [ L3] in an upper chord line frame model of the inverted triangular three-dimensional truss; after d is cut off from the other ends of the two long-span sidelines L1 and L2, repeating the previous step to obtain another group [ L4] of the upper chord wire frame model of the inverted triangular three-dimensional truss; cutting off line segments with the length of d/2 from both ends of two side lines L1 and L2 of the long span, repeating the previous step to obtain a line set [ L5], vertically translating the line in the [ L5] by h, wherein the value of h is the height of the input parameter truss, cutting off the line segment with the length of L/2 from both ends, wherein the value of L is equal to the length of the line segment in the [ L5] divided by n, and n is the number of horizontal segments of the input parameter to obtain a lower chord line set [ L6] of the inverted triangular three-dimensional truss; respectively equally dividing [ L3] and [ L4] into n sections to obtain lattices [ P1], [ P2], and equally dividing a line group [ L6] into n-1 sections to obtain lattices [ P3]; grouping and connecting points in the dot matrix [ P1] [ P2] [ P3] according to different combinations to obtain a diagonal web member line group, an upper chord tie rod line group and a purline line group, and finally integrating the diagonal web member line group, the upper chord tie rod line group and the purline line group to obtain an integral wire frame model [ X1] of the inverted triangular three-dimensional truss; and finally, integrating the wire group [ X1] [ X2] [ X3] to obtain a final truss string structure three-dimensional wire frame model [ X ].

4. The method of claim 1, wherein the structural types include a beam-string structure, a truss-string structure; the geometric control parameters comprise the number of transverse sections, the number of longitudinal sections, the height of the truss, the cable sag, the transverse spacing and the back-off distance; and fitting the building modeling surface to generate a string-structure three-dimensional wire frame model according to the characteristics of the building modeling through variable design parameters.

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