A method for modeling the distribution of sunshine shadow of a spatial steel structure

Abstract

This invention discloses a method for modeling the solar radiation and shadow distribution of a space steel structure, comprising: S1: obtaining real solar information at various times during the day; S2: using ANSYS software to calculate the three-dimensional point coordinates of the sun at each time and the solar incidence angle of the surface effect unit applying solar radiation heat flow; S3: filtering out the illuminated surface units in the space steel structure that do not consider mutual shading of members; S4: obtaining the number of the illuminated surface unit and its centroid coordinates; S5: exporting the three-dimensional point coordinates of the sun at each time and the number of the illuminated surface unit and its centroid coordinates into a first .txt file; S6: using Python software to generate the solar radiation unit number at each time; S7: exporting the solar radiation unit number at each time into a second .txt file; S8: using ANSYS software to read the second .txt file to generate the solar radiation and shadow distribution model of the space steel structure.

Description

Technical Field

[0001] This invention relates to the field of civil engineering structural technology, specifically to a method for modeling the solar shadow distribution of a spatial steel structure. Background Technology

[0002] Spatial steel structures, due to their advantages such as high load-bearing capacity, high degree of prefabrication, good seismic performance, and novel design, are often used as the superstructure of large public buildings such as stadiums, airport terminals, railway stations, and convention centers. Superstructures typically cover a large area, have a large overall weight, and unique shapes, thus requiring high precision and safety standards for high-altitude construction and assembly techniques.

[0003] Steel has a thermal conductivity approximately 34 times that of concrete, making it highly susceptible to thermal expansion and contraction with changes in external temperature. Since spatial steel structures are often highly statically indeterminate, redundant constraints prevent the effective release of temperature deformation, leading to secondary temperature stresses. Particularly under solar radiation, the temperature field of spatial steel structures exhibits significant non-uniformity and time-varying characteristics. The constituent members experience varying degrees of axial deformation, bending deformation, and non-uniform cross-sectional deformation. If the solar radiation temperature field of a spatial steel structure cannot be accurately calculated, temperature deformation may affect the high-altitude construction accuracy and safety of the steel roof, posing potential safety hazards for the construction and operation of large public buildings. Therefore, it is necessary to accurately calculate the solar radiation temperature field of spatial steel structures under solar radiation.

[0004] Currently, the main approach used is a combination of field experiments and numerical simulations to obtain the solar radiation temperature field distribution patterns of space steel structures. Numerical simulations of the solar radiation temperature field of space steel structures involve finite element model establishment, solar shading determination between members, and the application of boundary constraints. The finite element model is typically built using plate / shell elements or solid elements and surface effect elements (plate / shell elements or solid elements simulate heat conduction, while surface effect elements apply solar radiation heat flux) to effectively simulate the temperature deformation of the members and prevent local instability and failure of the space steel structure. Boundary constraints include short-wave solar radiation, air convection heat transfer, and long-wave radiation from the air and surrounding environment. Solar shading cannot be directly calculated in finite element software, and there is no readily available method for calculating it. It can be seen that the numerical simulation of the solar radiation temperature field of space steel structures is a complex, multidisciplinary computational process, and its accuracy is constrained by various factors, with solar shading determination being the most difficult and critical constraint to address.

[0005] There are two main existing methods for calculating solar shading: one is bounding box detection based on computer graphics, and the other is a geometric shading determination algorithm based on specific structural shapes. The first method targets finite element models built with rod elements, failing to consider the bending deformation and uneven cross-sectional deformation of steel rods under solar radiation. This makes it unable to reasonably represent the actual working state of the rods and neglects the risk of local buckling instability in spatial steel structures. Furthermore, it requires multiple coordinate transformations for each element under each load step, resulting in a large computational workload and making it unsuitable for calculating solar shading in large spatial steel structures such as steel roofs. The second method targets specific structures and cannot solve the problem of determining the solar shading of numerous intersecting rods in a spatial steel structure at different times.

[0006] Therefore, it is necessary to establish a joint simulation method based on finite element software and programming software to accurately calculate the distribution law of solar shading in spatial steel structures, and to solve the problem of difficult solar shading discrimination in numerical simulation of solar temperature field of spatial steel structures. Summary of the Invention

[0007] The purpose of this invention is to provide a method for modeling the solar shadow distribution of a space steel structure, so as to solve the problem of difficulty in calculating the solar shadow distribution law under different solar positions in the numerical simulation of solar temperature field of space steel structure, and improve the application scope of solar shadow calculation.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0009] This invention provides a method for modeling the solar shading distribution of a spatial steel structure, the method comprising:

[0010] S1: Obtain real-time solar information for each moment of the day;

[0011] S2: Based on the real solar information, the three-dimensional point coordinates of the sun at each moment and the solar incidence angle of the surface effect unit that applies solar radiation heat flow are calculated using ANSYS software.

[0012] S3: Based on the solar incidence angle, screen the light-receiving surface units in the space steel structure that do not consider mutual shading of the members;

[0013] S4: Obtain the number of the illuminated surface unit and its centroid coordinates;

[0014] S5: Using the macro file function of ANSYS software, export the coordinates of the three-dimensional points of the sun at each moment and the number of the illuminated surface unit and its centroid coordinates into a first .txt file;

[0015] S6: Based on the first .txt file, use Python software to generate the solar radiation unit number for each time moment;

[0016] S7: Export the solar radiation unit numbers for each time moment into a second .txt file;

[0017] S8: Use ANSYS software to read the second .txt file to generate a solar shading distribution model of the spatial steel structure.

[0018] Alternatively, in step S1, the real solar-related information includes the real solar altitude angle and the real solar azimuth angle.

[0019] Alternatively, in step S2, the solar incidence angle is:

[0020]

[0021] Wherein, cos_e(enum,x) is the cosine of the angle between the normal of the surface element numbered enum and the x-axis; cos_s(stime,x) is the cosine of the angle between the incident sunlight and the x-axis at time stime; cos_e(enum,y) is the cosine of the angle between the normal of the surface element numbered enum and the y-axis; cos_s(stime,y) is the cosine of the angle between the incident sunlight and the y-axis at time stime; cos_e(enum,z) is the cosine of the angle between the normal of the surface element numbered enum and the z-axis; and cos_s(stime,z) is the cosine of the angle between the incident sunlight and the z-axis at time stime.

[0022] Optionally, step S3 includes: using the cosine of the solar incident angle being greater than zero to screen the light-receiving surface units in the space steel structure that do not consider mutual shading between members.

[0023] Alternatively, step S6 may include:

[0024] S61: Based on the coordinates of the three-dimensional point of the sun at each moment in the first .txt file, use Python software to calculate the direction vector of the sun's incident rays passing through the origin at each moment.

[0025] S62: Use the point-normal equation to determine the plane equation that passes through the origin and is perpendicular to the direction vector of the solar incident ray at each time, and use the point-direction equation to determine the straight line equation that passes through the coordinates of the centroid of each unit at each time.

[0026] S63: Determine the intersection points with the linear equation and the plane equation at each time point, and the intersection point number is consistent with the corresponding element number;

[0027] S64: Select one intersection point from the set of intersection points at the target time as the primary intersection point, and the remaining intersection points are potential secondary intersection points. The absolute value of the difference between the Z-value of the centroid coordinate corresponding to the primary intersection point number and the Z-value of the centroid coordinate corresponding to the secondary intersection point number should be greater than a limit value. This limit value is related to the shape of the spatial steel structure and the cross-sectional shape of the constituent members.

[0028] S65: Calculate the distance between the primary intersection point and each of the secondary intersection points;

[0029] It should be noted that the spacing here is actually a set of spacings. If all spacings in this set are greater than the control value, the sunshine unit is the principal intersection point. If there are cases where the spacing is less than the control value, which may be that many spacings are less than the control value, then the intersection point with the largest Z value among the principal intersection points of these spacings is extracted and the intersection point number is the sunshine unit.

[0030] S66: Determine whether the distance between the intersection points is greater than the control value. If so, determine that the unit corresponding to the main intersection point number is the sunshine unit. Otherwise, determine that the unit with the largest centroid coordinate Z value among the main intersection point number and the units corresponding to each secondary intersection point number that satisfy the condition that the distance between the intersection points is less than the control value is the sunshine unit.

[0031] S67: Repeat steps S64-S66 until the solar unit number of the last intersection point in the intersection point set at the target time is obtained as the main intersection point, and remove the duplicate solar unit numbers in the entire target time before proceeding to step S68.

[0032] S68: Take the next moment as the target moment and return to step S64 until all moments are traversed to obtain the solar radiation unit for each moment.

[0033] Alternatively, in step S62, the point-normal equation is:

[0034] s1×(xx p )+s2×(yy p )+s3×(zz p ) = 0

[0035] The point-direction equation is:

[0036]

[0037] Where s(s1,s2,s3) is the vector of sunlight pointing to the origin; p(x p ,y p ,z p Let ) be a point on the plane; l(x) l ,y l ,z l () is a point on the straight line.

[0038] Alternatively, in step S65, the spacing is calculated in the following manner:

[0039]

[0040] Where ΔL is the distance between two points in space; k is the control value for the distance between intersection points; (x a ,y a ,z a ) and (x b ,y b ,z b ) are the coordinates of points a and b in space, respectively.

[0041] The present invention has the following beneficial effects:

[0042] (1) This invention can accurately calculate the solar shadow distribution of a spatial steel structure finite element model established with plate and shell elements or solid elements, and can even calculate the solar shadow distribution of a bridge. It has a wide range of applications.

[0043] (2) This invention realizes the joint simulation of finite element software and programming software in solar shadow calculation through common .txt files, avoiding problems such as difficulty in associating, calling and error-prone interfaces between finite element software and programming software. It can also accurately calculate solar shadow of structures using different finite element software and programming software.

[0044] (3) This invention is applicable to the calculation of solar shadows in complex structures. The accuracy of the solar shadow calculation can be adjusted according to different structures, rod cross-sectional dimensions, and unit dimensions. It has strong applicability and high calculation accuracy.

[0045] (4) In this invention, the elements that are occluded by the members themselves have been removed in the ANSYS software. Only the shadow elements that are occluded between the members are calculated in Python. For large finite element models, this can save a lot of calculation time.

[0046] (5) The solar shading determination algorithm in this invention is based on the basic theoretical knowledge of computer graphics. The algorithm logic is clear and easy to understand, and it is easy for different people to get started. It has good application prospects in practical applications such as solar temperature field numerical simulation and solar shading visualization technology. Attached Figure Description

[0047] Figure 1 This is a flowchart of the solar shadow distribution modeling method for spatial steel structures according to the present invention. Detailed Implementation

[0048] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0049] This invention provides a method for modeling the solar shading distribution of a spatial steel structure, with reference to... Figure 1 As shown, the method for modeling the solar shading distribution of the spatial steel structure includes:

[0050] S1: Obtain real-time solar information for each moment of the day;

[0051] The true solar information at various times during the day is obtained through on-site measurements or theoretical calculations. The true solar information includes the true solar altitude angle and the true solar azimuth angle.

[0052] S2: Based on the real solar information, the three-dimensional point coordinates of the sun at each moment and the solar incidence angle of the surface effect unit that applies solar radiation heat flow are calculated using ANSYS software.

[0053] Here, knowledge of spatial analytic geometry is utilized, namely:

[0054]

[0055]

[0056] cosθ=cos_e(enum,x)×cos_s(stime,x)+cos_e(enum,y)×cos_s(stime,y)

[0057] +cos_e(enum,z)×cos_s(stime,z)

[0058] In the formula, h s Solar altitude angle; γ s This is the solar azimuth angle; δ represents the geographical latitude; Ω represents the solar declination angle; cos_e(enum,x) is the cosine of the angle between the normal of the surface element numbered enum and the x-axis; cos_s(stime,x) is the cosine of the angle between the incident solar ray at time stime and the x-axis; cos_e(enum,y) is the cosine of the angle between the normal of the surface element numbered enum and the y-axis; cos_s(stime,y) is the cosine of the angle between the incident solar ray at time stime and the y-axis; cos_e(enum,z) is the cosine of the angle between the normal of the surface element numbered enum and the z-axis; cos_s(stime,z) is the cosine of the angle between the incident solar ray at time stime and the z-axis.

[0059] Therefore, the solar incidence angle is:

[0060]

[0061] S3: Based on the solar incidence angle, screen the light-receiving surface units in the space steel structure that do not consider mutual shading of the members;

[0062] This invention utilizes the fact that the cosine of the solar incidence angle is greater than zero to filter out sunlit surface units in spatial steel structures that do not consider mutual shading between members. This saves a significant amount of computation time in subsequent solar shading determination.

[0063] S4: Obtain the number of the illuminated surface unit and its centroid coordinates;

[0064] S5: Using the macro file function of ANSYS software, export the coordinates of the three-dimensional points of the sun at each moment and the number of the illuminated surface unit and its centroid coordinates into a first .txt file;

[0065] S6: Based on the first .txt file, use Python software to generate the solar radiation unit number for each time moment;

[0066] Alternatively, step S6 may include:

[0067] S61: Based on the coordinates of the three-dimensional point of the sun at each moment in the first .txt file, use Python software to calculate the direction vector of the sun's incident rays passing through the origin at each moment.

[0068] S62: Use the point-normal equation to determine the plane equation that passes through the origin and is perpendicular to the direction vector of the solar incident ray at each time, and use the point-direction equation to determine the straight line equation that passes through the coordinates of the centroid of each unit at each time.

[0069] The point-normal equation is:

[0070]

[0071] The point-direction equation is:

[0072]

[0073] Where s(s1,s2,s3) is the vector of sunlight pointing to the origin; p(x p ,y p ,z p ) is a point on the plane, which is the origin in this invention; l(x) l ,y l ,z l () is a point on the straight line, and in this invention, it is the coordinate of the centroid of the unit.

[0074] S63: Determine the intersection points with the linear equation and the plane equation at each time point, and the intersection point number is consistent with the corresponding element number;

[0075] It should be noted that the coordinates of the intersection point are first obtained by solving the point-normal equation and the point-direction equation simultaneously, and then t is substituted into the point-direction equation to obtain the final coordinates.

[0076] S64: Select one intersection point from the set of intersection points at the target time as the primary intersection point, and the remaining intersection points are potential secondary intersection points. The absolute value of the difference between the Z-value of the centroid coordinate corresponding to the primary intersection point number and the Z-value of the centroid coordinate corresponding to the secondary intersection point number should be greater than a limit value. This limit value is related to the shape of the spatial steel structure and the cross-sectional shape of the constituent members.

[0077] That is: |z 主 -z 次 |≥m, where m is a limit value.

[0078] S65: Calculate the distance between the primary intersection point and each of the secondary intersection points;

[0079] The spacing is calculated in the following way:

[0080]

[0081] Where ΔL is the distance between two points in space; k is the control value for the distance between intersection points; (x a ,y a ,z a ) and (x b ,y b ,z b ) are the coordinates of points a and b in space, respectively.

[0082] S66: Determine whether the distance between the intersection points is greater than the control value. If so, determine that the unit corresponding to the main intersection point number is the sunshine unit. Otherwise, determine that the unit with the largest centroid coordinate Z value among the main intersection point number and the units corresponding to each secondary intersection point number that satisfy the condition that the distance between the intersection points is less than the control value is the sunshine unit.

[0083] S67: Repeat steps S64-S66 until the solar unit number of the last intersection point in the intersection point set at the target time is obtained as the main intersection point, and remove the duplicate solar unit numbers in the entire target time before proceeding to step S68.

[0084] S68: Take the next moment as the target moment and return to step S64 until all moments are traversed to obtain the solar radiation unit for each moment.

[0085] S7: Export the solar radiation unit numbers for each time moment into a second .txt file;

[0086] It should be noted that the entire Python program needs to import the math, os.path, time, and datetime modules using the import statement. By creating a few functions, the calculation of the number of the shadow unit of the solar unit or the shadow unit of the mutual shading of the rods at each time can be easily completed, so as to achieve the purpose of real-time calculation of solar shadow of the spatial steel structure.

[0087] S8: Use ANSYS software to read the second .txt file to generate a solar shading distribution model of the spatial steel structure.

[0088] That is, the macro file function of ANSYS software is used again to read the solar radiation unit number or the shadow unit number of mutual shading of the rods calculated by Python software into the ANSYS software array, as the result of solar radiation shading determination in the numerical simulation of solar radiation temperature field of space steel structure.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for modeling the solar shading distribution of a spatial steel structure, characterized in that, The method for modeling the solar shading distribution of the spatial steel structure includes: S1: Obtain real-time solar information for each moment of the day; S2: Based on the real solar information, the three-dimensional point coordinates of the sun at each moment and the solar incidence angle of the surface effect unit that applies solar radiation heat flow are calculated using ANSYS software. S3: Based on the solar incidence angle, screen the light-receiving surface units in the space steel structure that do not consider mutual shading of the members; S4: Obtain the number of the illuminated surface unit and its centroid coordinates; S5: Using the macro file function of ANSYS software, export the coordinates of the three-dimensional points of the sun at each moment and the number of the illuminated surface unit and its centroid coordinates into a first .txt file; S6: Based on the first .txt file, use Python software to generate the solar radiation unit number for each time moment; S7: Export the solar radiation unit numbers for each time moment into a second .txt file; S8: Use ANSYS software to read the second .txt file to generate a solar shading distribution model of the spatial steel structure; Step S6 includes: S61: Based on the coordinates of the three-dimensional point of the sun at each moment in the first .txt file, use Python software to calculate the direction vector of the sun's incident rays passing through the origin at each moment. S62: Use the point-normal equation to determine the plane equation that passes through the origin and is perpendicular to the direction vector of the solar incident ray at each time, and use the point-direction equation to determine the straight line equation that passes through the coordinates of the centroid of each unit at each time. S63: Determine the intersection points with the linear equation and the plane equation at each time point, and the intersection point number is consistent with the corresponding element number; S64: Select one intersection point from the set of intersection points at the target time as the primary intersection point, and the remaining intersection points are potential secondary intersection points. The absolute value of the difference between the Z-value of the centroid coordinate corresponding to the primary intersection point number and the Z-value of the centroid coordinate corresponding to the secondary intersection point number should be greater than a limit value. This limit value is related to the shape of the spatial steel structure and the cross-sectional shape of the constituent members. S65: Calculate the distance between the primary intersection point and each of the secondary intersection points; S66: Determine whether the distance between the intersection points is greater than the control value. If so, determine that the unit corresponding to the main intersection point number is the sunshine unit. Otherwise, determine that the unit with the largest centroid coordinate Z value among the main intersection point number and the units corresponding to each secondary intersection point number that satisfy the condition that the distance between the intersection points is less than the control value is the sunshine unit. S67: Repeat steps S64-S66 until the solar unit number of the last intersection point in the intersection point set at the target time is obtained as the main intersection point, and remove the duplicate solar unit numbers in the entire target time before proceeding to step S68. S68: Take the next moment as the target moment and return to step S64 until all moments are traversed to obtain the solar radiation unit for each moment.

2. The method for modeling the solar radiation and shadow distribution of a spatial steel structure according to claim 1, characterized in that, In step S1, the real solar-related information includes the real solar altitude angle and the real solar azimuth angle.

3. The method for modeling the solar shading distribution of a spatial steel structure according to claim 2, characterized in that, In step S2, the solar incidence angle is: in, Let be the cosine of the angle between the normal of the face element numbered enum and the x-axis; Let be the cosine of the angle between the incident solar ray at time stime and the x-axis; Let y be the cosine of the angle between the normal of the face element numbered enum and the y-axis. Let y be the cosine of the angle between the incident sun ray at time stime and the y-axis. Let be the cosine of the angle between the normal of the surface element numbered enum and the z-axis; Let be the cosine of the angle between the incident solar ray at time stime and the z-axis.

4. The method for modeling the solar shading distribution of a spatial steel structure according to any one of claims 1 to 3, characterized in that, Step S3 includes: using the fact that the cosine of the solar incident angle is greater than zero, screening out the light-receiving surface units in the space steel structure that do not consider mutual shading of the members.

5. The method for modeling the solar radiation and shadow distribution of a spatial steel structure according to claim 1, characterized in that, In step S62, the point-normal equation is: The point-direction equation is: in, The vector of sunlight pointing towards the origin; Let it be a point on the plane; Let be a point on the straight line.

6. The method for modeling the solar radiation and shadow distribution of a spatial steel structure according to claim 1, characterized in that, In step S65, the spacing is calculated in the following way: in, The distance between two points in space; k This is the control value for the distance between intersection points; and Separate spaces a Point and b The coordinates of the point.

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