Method for establishing mesoscopic finite element model of single-layer reinforced ultra-high performance concrete structure

Abstract

The invention discloses a method for establishing a mesoscopic finite element model of a single-layer steel bar ultra-high performance concrete structure, and belongs to the technical field of fiber mesoscopic concrete simulation. According to the method, firstly, steel bars meeting arrangement requirements are generated in a set area, fibers are randomly put in the area, the fibers are adjusted according to relevant parameters of the fibers and the steel bars until it is confirmed that no invasion and intersection phenomena occur between the fibers and all the steel bars, and it is ensured that no invasion phenomenon exists in a finally-established reinforced concrete member model. According to the method, modeling is conducted on a large number of fibers, accurate modeling is conducted on the single-layer steel bars arranged in the two directions, the intrusion defect between the fibers and the steel bars is overcome, a simulation model is closer to reality, and the accuracy of a simulation result is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber meso-concrete simulation, and in particular relates to a method for establishing a meso-finite element model of a single-layer reinforced ultra-high performance concrete structure. Background Art

[0002] At the macroscopic scale, reinforced ultra-high performance concrete structures are usually simplified as homogeneous materials for mechanical analysis. However, in reality, reinforced ultra-high performance concrete structures are typical heterogeneous materials, consisting of a multiphase composite material composed of matrix, steel bars and steel fibers. At present, the modeling methods of such structures mostly rely on macroscopic mechanical models, which often ignore the complex characteristics inside the structure. Although this simplified method is suitable for the study of overall performance, it cannot fully reveal the complexity, deformation mode and failure mechanism of the internal components of the composite structure. In addition, there is often a size effect in macroscopic mechanical tests. As the size of the structure increases, the size effect will become more significant, making the applicability of the macroscopic constitutive model applicable to a certain size reduced at different sizes. Therefore, by establishing an accurate mesoscopic model, the size effect in the macroscopic mechanical model can be effectively circumvented. Developing a mesoscopic model that can accurately reflect the internal components and their distribution of reinforced ultra-high performance concrete structures is crucial for a deep understanding and prediction of the performance of the structure. Summary of the invention

[0003] The purpose of the present invention is to provide a method for establishing a mesoscopic finite element model of a reinforced ultra-high performance concrete structure based on Monte Carlo with flexible layout and high accuracy. By establishing an accurate mesoscopic model, the size effect in the macroscopic mechanical model is avoided, the internal components and their distribution of the reinforced ultra-high performance concrete structure are accurately reflected, and an in-depth understanding and prediction of the performance of the structure are achieved.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure is characterized by comprising the following steps:

[0006] S1. Determine the size and volume of the concrete cube: the length of the cube is LX, the width of the cube is LY, and the height of the cube is LZ, then the volume of the concrete is: V = LX·LY·LZ;

[0007] S2. Complete the setting and calculation of steel bar related parameters: set the thickness of the concrete cover in the X-axis, Y-axis and Z-axis directions, the length, width and height of the cube in the delivery area, and calculate the length of the steel bars in the X-axis and Y-axis directions; calculate the spacing of the transverse and longitudinal steel bars according to the number of transverse and longitudinal steel bars; arrange the first transverse and longitudinal steel bars in the delivery area and determine the coordinates, complete the steel bar arrangement according to the spacing translation, and save the steel bar coordinates;

[0008] S3, fiber delivery area and related parameter settings: determine the minimum and maximum delivery coordinate points of the X, Y and Z axes, and then determine the fiber delivery range, determine the delivery quantity according to the selected fiber size parameters, and perform random delivery;

[0009] S4. Adjustment of fiber placement boundary and determination of fiber invasion with steel bars: After all fibers are randomly placed, their starting point coordinates and end point coordinates are determined, and the fiber coordinates beyond the placement boundary are adjusted. After the adjustment is completed, the invasion between the fiber and the steel bar is determined, and the fiber invading the steel bar is deleted and regenerated until all fibers and all steel bars do not invade or intersect, and the fiber coordinates are saved;

[0010] S5: Establishment of finite element model: After completing all the required fiber placement and steel bar arrangement, arrange and number the coordinate information of the fibers and steel bars, convert their endpoint coordinates into finite element simulation nodes, renumber and arrange the node information to make it unit information recognizable by the finite element software, and use the fopen function in the MATLAB software to save it in the form of a keyword K file recognizable by the finite element analysis software ANSYS / LS-DYNA; the matrix finite element model can be generated by finite element software such as ANSYS / LS-DYNA, and the generated homogeneous finite element model can be exported in the form of a k file.

[0011] As a further description of the technical solution of the present invention:

[0012] After all the steel bars are arranged in S2, the starting coordinates of all the horizontal and vertical steel bars are saved in g_node1 in the form of a matrix according to the generation order, and the ending coordinates of all the horizontal and vertical steel bars are saved in g_node2 in the form of a matrix according to the generation order;

[0013] After the fiber placement is completed in S4, the starting point coordinates of the fibers that meet the requirements are saved in end_node1 in a matrix form, and the ending point coordinates of the fibers are saved in end_node2 in a matrix form;

[0014] The steps of node information arrangement in S5 are as follows: create a column vector BH4 with a length equal to the number of steel bars O, define its value as 0, connect BH4 with g_node1 and g_node2 to form a longer node vector; extract the row number A of end_node1 (i.e. the number of nodes of end_node1) and the row number B of end_node2 (i.e. the number of nodes of end_node2), create a column vector BH from 1 to A+B+O (the sum of the number of steel bars and the number of fibers), which is used for subsequent node numbering; arrange the node information in end_node1 and end_node2 in order, and connect the arranged node matrix with BH to form a longer node vector; initialize a zero matrix NODE with a size of (3·A+3·O, 5) to store the coordinates and other information of the nodes, and arrange the processed node information in the required order to obtain the total node set;

[0015] The steps for arranging the cell information are: create a column vector BH1 from 1 to A+O, create a column vector BH2 ​​from A+O+1 to A+B+2·O, create a column vector BH3 from A+B+2·O+1 to A+B+3·O for element numbering, create a column vector PART with a length of A+B, define its row values ​​from 1 to A as 100, define its values ​​from A+1 to A+O as 101, and combine PART, BH1, BH2, and BH3 into an overall cell matrix.

[0016] As a further description of the technical solution of the present invention:

[0017] The length of the steel bar in S2 is:

[0018] G-lx=LX-2 px,

[0019] G-ly=LY-2·py,

[0020] Among them, px is the thickness of the concrete cover in the X-axis direction, py is the thickness of the concrete cover in the Y-axis direction, G-lx is the length of the steel bar in the X-axis direction, and G-ly is the length of the steel bar in the Y-axis direction;

[0021] Determine the number of longitudinal reinforcement nx and the number of transverse reinforcement ny, and calculate the spacing between the reinforcements:

[0022] JX=G-lx / (nx-1),

[0023] JY=G-ly / (ny-1),

[0024] Among them, JX is used to determine the longitudinal reinforcement spacing, and JY is the transverse reinforcement spacing.

[0025] As a further description of the technical solution of the present invention:

[0026] In S2, the starting coordinates of the first transverse reinforcement are first specified in the placement area, the ending coordinates of the first reinforcement are calculated using the reinforcement-related parameters, the three coordinates of the reinforcement in the Cartesian coordinate system are saved, the starting coordinates and ending coordinates of the first transverse reinforcement are translated, and the starting coordinates and ending coordinates of the second transverse reinforcement are obtained, until the arrangement of the transverse reinforcement is completed.

[0027] The starting point coordinates of the transverse reinforcement (X1 g , Y1 g , Z1 g ) is calculated as follows:

[0028] X1 g =px,

[0029] Y1 g =py+JY·(i-1)i∈[1,ny],

[0030] Z1 g =pz,

[0031] Transverse reinforcement end point coordinates (X2 g , Y2 g , Z2 g ) is calculated as follows:

[0032] X2 g =px+G-lx,

[0033] Y2 g =py+JY·(i-1)i∈[1,ny],

[0034] Z2 g =pz,

[0035] After all transverse reinforcements are arranged, the starting coordinates of the first longitudinal reinforcement are calculated in the delivery area, and the ending coordinates of the first longitudinal reinforcement are calculated using the reinforcement-related parameters. The three coordinates of the reinforcement in the Cartesian coordinate system are saved, and the starting coordinates and ending coordinates of the first longitudinal reinforcement are translated to obtain the starting coordinates and ending coordinates of the second longitudinal reinforcement until the longitudinal reinforcement arrangement is completed.

[0036] The starting point coordinates of the longitudinal reinforcement (X3 g , Y3 g , Z3 g ) is calculated as follows:

[0037] X3 g =px+JX·(i-1)i∈[1,nx]

[0038] Y3 g =py,

[0039] Z3 g =pz+G-dia,

[0040] The end point coordinates of the longitudinal reinforcement (X4 g , Y4 g , Z4 g ) is calculated as follows:

[0041] X4 g =px+JX·(i-1)i∈[1,nx],

[0042] Y4 g =py+G-ly,

[0043] Z4 g =pz+G-dia,

[0044] Among them, pz is the thickness of the concrete cover in the Z-axis direction, and G-dia is the diameter of the steel bar section.

[0045] As a further description of the technical solution of the present invention:

[0046] The formula for calculating the delivery range in S3 is as follows:

[0047] x-min=x0,

[0048] x-max=x0+Lx1,

[0049] y-min=y0,

[0050] y-max=y0+Ly1,

[0051] z-min=z0,

[0052] z-max=z0+Lz1,

[0053] Among them, x0 is the minimum delivery coordinate point of the delivery range on the X axis, y0 is the minimum delivery coordinate point of the delivery range on the Y axis, z0 is the minimum delivery coordinate point of the delivery range on the Z axis, Lx1 is the maximum delivery coordinate point of the delivery range on the X axis, Ly1 is the maximum delivery coordinate point of the delivery range on the Y axis, and Lz1 is the maximum delivery coordinate point of the delivery range on the Z axis.

[0054] As a further description of the technical solution of the present invention:

[0055] The calculation formula for the number of fibers m put in S3 is as follows:

[0056]

[0057] Where dia is the fiber cross-sectional diameter, ratio is the fiber volume content, and Ln is the fiber length.

[0058] As a further description of the technical solution of the present invention:

[0059] The method for determining the starting point and direction vector of the fiber in S3 is as follows:

[0060] Use the rand function rand(1), which generates a random number between 0 and 1. The formula for calculating the starting point coordinates is as follows:

[0061] The X coordinate of the starting point of each fiber is randomly generated as: x1 = LX rand (1),

[0062] The Y coordinate of the starting point of each fiber is randomly generated as: y1 = LY rand (1),

[0063] The Z coordinate of the starting point of each fiber is randomly generated as: z1 = LZ rand (1),

[0064] Use angle1 to represent the angle of the direction vector in the xy plane, and angle2 to represent the inclination angle of the direction vector in the zy plane. The calculation formula is as follows:

[0065] angle1=2·π·rand(1),

[0066] angle2=2·π·rand(1),

[0067] angle1 and angle2 represent random angles in the range of 0 to 2π;

[0068] The fiber end point coordinates are calculated using the starting point coordinates and random angles angle1 and angle2. The calculation formula is as follows:

[0069] The X coordinate of the end point of each fiber is randomly generated as: x2 = x1 + Ln·cos(angle2)·cos(angle1),

[0070] The Y coordinate of the end point of each fiber is randomly generated as: y2 = y1 + Ln·cos(angle2)·sin(angle1),

[0071] The Z coordinate of the end point of each fiber is randomly generated as: z2=z1+Ln·sin(angle2).

[0072] As a further description of the technical solution of the present invention:

[0073] After all the fibers are placed, their starting point coordinates and end point coordinates are determined. When their starting point coordinates and end point coordinates exceed the minimum placement boundary of the placement area, their coordinates are automatically corrected to be 1 mm inwardly offset from the minimum placement boundary. The calculation formula is as follows:

[0074] x1=x-min+0.001,

[0075] y1=y-min+0.001,

[0076] z1=z-min+0.001,

[0077] x2=x-min+0.001,

[0078] y2=y-min+0.001,

[0079] z2=z-min+0.001,

[0080] When the starting point coordinates and the end point coordinates exceed the maximum delivery boundary of the delivery area, the coordinates are automatically corrected to be offset 1 mm inward from the maximum delivery boundary. The calculation formula is as follows:

[0081] x1=x-max-0.001,

[0082] y1=y-max-0.001,

[0083] z1=z-max-0.001,

[0084] x2=x-max-0.001,

[0085] y2=y-max-0.001,

[0086] z2=z-max-0.001.

[0087] As a further description of the technical solution of the present invention:

[0088] When the fiber and the steel bar are intruded, the starting coordinates POINT-P1 (x1, y1, z1) and the end coordinates POINT-P2 (x2, y2, z2) of the first fiber are extracted, and the starting coordinates POINT-A (x1, y1, z1) of the first steel bar in the matrix g_node1 are extracted. G 1,Y G 1,Z G 1) The corresponding end point coordinates POINT-B (X G 2,Y G 2,Z G 2) When the fiber and the steel bar intrude and intersect in the matrix space, the shortest distance from the coordinates of the two end points of the fiber to the direction vector of the steel bar is calculated respectively. The calculation formula is as follows:

[0089]

[0090]

[0091]

[0092]

[0093]

[0094] Calculate the two intersection points of the shortest distance vector and the steel bar direction vector. The calculation formula is as follows:

[0095]

[0096]

[0097] After finding the midpoint coordinates C of the two intersection points, use the midpoint coordinates C to calculate the shortest distance Dist from the midpoint coordinates to the fiber. The calculation formula is as follows:

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106] Finally, the minimum value among Dist, Dist1, and Dist2 is taken as the shortest distance from the fiber to the steel bar. By judging its relationship with the sum of the cross-sectional radius of the fiber steel bar, it is decided whether to delete the fiber and regenerate it.

[0107] After completing the judgment of the intrusion relationship between the first fiber and the first steel bar in the matrix g_node1 and g_node2, the intrusion relationship between the first fiber and all the remaining steel bars in g_node1 and g_node2 is judged cyclically;

[0108] After completion, the intrusion relationship between the second fiber and all the steel bars in g_node1 and g_node2 is judged until the intrusion judgment of all fibers and all steel bars is completed;

[0109] The newly generated fiber needs to re-determine whether it intrudes into each steel bar in g_node1 and g_node2, until all fibers do not intrude or intersect with all steel bars.

[0110] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0111] Currently, most concrete micro-modeling technologies only include a single fiber component and a steel component, and rarely include all components of ultra-high performance concrete steel composite structures. This method models a large number of fibers and accurately models single-layer steel bars arranged in two directions, solving the intrusion defects between fibers and steel bars. The simulation model is closer to reality, which improves the accuracy of the simulation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] Figure 1 This is a finite element model diagram of the ultra-high performance concrete reinforced composite structure fiber of the present invention;

[0113] Figure 2 This is a finite element model diagram of the steel bars of the ultra-high performance concrete steel bar composite structure of the present invention;

[0114] Figure 3 It is a finite element model diagram of the cross section of the ultra-high performance concrete reinforced steel composite structure of the present invention. DETAILED DESCRIPTION

[0115] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0116] Example 1: Establishing a finite element model of an ultra-high performance concrete single-layer bidirectional reinforced composite structure. Figure 1-3 :

[0117] Step 1: Generate basic information of ultra-high performance concrete reinforced composite structure in MATLAB software. Generate two rows of horizontal and vertical line segments in the pointed area. Since the geometric shape of the steel bar is similar to the line segment, the line segment arranged in a directional manner can be considered as the steel bar. On this basis, generate random fibers. Since the geometric shape of the fiber is similar to the line segment, the random line segment can be considered as the fiber.

[0118] The specific process is as follows:

[0119] 1.1. Use MATLAB language to declare the relevant parameters required for fibers and steel bars

[0120] Determine the size and volume of a concrete cube: If the length of the cube is LX, the width of the cube is LY, and the height of the cube is LZ, then the volume of the concrete is:

[0121] V = LX·LY·LZ;

[0122] The relevant parameters include the concrete cover thickness px in the X-axis direction, the concrete cover thickness py in the Y-axis direction, the concrete cover thickness pz in the Z-axis direction, the steel bar cross-sectional diameter G-dia, the number of longitudinal steel bars arranged nx and the number of transverse steel bars arranged ny; the fiber-related parameters include the fiber cross-sectional diameter dia, the fiber volume content ratio, and the fiber length Ln.

[0123] 1.2. Complete the calculation of steel bar related parameters

[0124] According to the thickness of the concrete cover in the X-axis, Y-axis and Z-axis directions, and the length, width and height of the cube in the delivery area, the length of the steel bars in the X-axis and Y-axis directions is calculated; according to the number of transverse and longitudinal steel bars, the spacing between the transverse and longitudinal steel bars is calculated. The transverse steel bar length G-lx and the longitudinal steel bar length G-ly, the spacing between the transverse steel bars JY and the spacing between the longitudinal steel bars JX are as follows:

[0125] G-lx=LX-2 px,

[0126] G-ly=LY-2·py,

[0127] Spacing between steel bars:

[0128] JX=G-lx / (nx-1),

[0129] JY = G-ly / (ny-1).

[0130] 1.3. Horizontal and vertical reinforcement arrangement

[0131] The reinforcement placement area is the interior of the concrete cube. First, specify the starting coordinates of the first transverse reinforcement in the placement area, calculate the end coordinates of the first reinforcement using the reinforcement-related parameters, save the three coordinates of the reinforcement in the Cartesian coordinate system, translate the starting coordinates and end coordinates of the first transverse reinforcement, and obtain the starting coordinates and end coordinates of the second transverse reinforcement until the arrangement of the transverse reinforcement is completed.

[0132] The starting point coordinates of the transverse reinforcement (X1 g , Y1 g , Z1 g ) is calculated as follows:

[0133] X1 g =px,

[0134] Y1 g =py+JY·(i-1)i∈[1,ny],

[0135] Z1 g =pz,

[0136] Transverse reinforcement end point coordinates (X2 g , Y2 g , Z2 g ) is calculated as follows:

[0137] X2 g =px+G-lx,

[0138] Y2 g =py+JY·(i-1)i∈[1,ny],

[0139] Z2 g =pz,

[0140] For easy identification, the numbers in the coordinates reflect the starting point or end point, where the starting point of the transverse reinforcement is represented by the number 1 and the end point is represented by the number 2, and the starting point of the longitudinal reinforcement is represented by the number 3 and the end point is represented by the number 4. The naming of coordinates is mainly used to distinguish the operation of computer programs, and other naming methods can also be sampled.

[0141] After all transverse reinforcements are arranged, the starting coordinates of the first longitudinal reinforcement are calculated in the delivery area, and the ending coordinates of the first longitudinal reinforcement are calculated using the reinforcement-related parameters. The three coordinates of the reinforcement in the Cartesian coordinate system are saved, and the starting coordinates and ending coordinates of the first longitudinal reinforcement are translated to obtain the starting coordinates and ending coordinates of the second longitudinal reinforcement until the longitudinal reinforcement arrangement is completed.

[0142] The starting point coordinates of the longitudinal reinforcement (X3 g , Y3 g , Z3 g ) is calculated as follows:

[0143] X3 g =px+JX·(i-1)i∈[1,nx]

[0144] Y3 g =py,

[0145] Z3 g =pz+G-dia,

[0146] The end point coordinates of the longitudinal reinforcement (X4 g , Y4 g , Z4 g ) is calculated as follows:

[0147] X4 g =px+JX·(i-1)i∈[1,nx],

[0148] Y4 g =py+G-ly,

[0149] Z4g =pz+G-dia,

[0150] After completing the arrangement of all steel bars, the starting coordinates of all horizontal and vertical steel bars are saved in g_node1 in the form of a matrix according to the generation order, and the ending coordinates of all horizontal and vertical steel bars are saved in g_node2 in the form of a matrix according to the generation order.

[0151] 1.4 Fiber calculation and placement

[0152] A certain amount of random fibers are placed in the designated area, and the fiber placement area and related parameters are set. The minimum placement coordinate point x0 on the X axis of the placement range, the minimum placement coordinate point y0 on the Y axis of the placement range, the minimum placement coordinate point z0 on the Z axis of the placement range, the maximum placement coordinate point Lx1 on the X axis of the placement range, the maximum placement coordinate point Ly1 on the Y axis of the placement range, the maximum placement coordinate point Lz1 on the Z axis of the placement range, the fiber cross-sectional diameter dia, the fiber volume content ratio, and Ln is the fiber length. The placement range calculation formula is as follows:

[0153] x-min=x0,

[0154] x-max=x0+Lx1,

[0155] y-min=y0,

[0156] y-max=y0+Ly1,

[0157] z-min=z0,

[0158] z-max=z0+Lz1,

[0159] The calculation formula for the fiber delivery quantity m is as follows:

[0160]

[0161] The fibers are randomly placed, and the method of randomly placing the fibers is as follows:

[0162] Determine the starting point and direction vector of the fiber, and use the rand function rand(1), which represents the generation of a random number between 0 and 1. The formula for calculating the starting point coordinates is as follows:

[0163] Randomly generate the X coordinate of the starting point of each fiber: x1 = LX rand (1)

[0164] The Y coordinate of the starting point of each fiber is randomly generated: y1 = LY rand (1),

[0165] Randomly generate the Z coordinate of the starting point of each fiber: z1 = LZ rand (1),

[0166] Use angle1 to represent the angle of the direction vector in the xy plane, and angle2 to represent the inclination angle of the direction vector in the zy plane. The calculation formula is as follows:

[0167] angle1=2·π·rand(1),

[0168] angle2=2·π·rand(1),

[0169] angle1 and angle2 represent random angles in the range of 0 to 2π;

[0170] The fiber end point coordinates are calculated using the starting point coordinates and random angles angle1 and angle2. The calculation formula is as follows:

[0171] The X coordinate of the end point of each fiber is randomly generated as: x2 = x1 + Ln·cos(angle2)·cos(angle1),

[0172] The Y coordinate of the end point of each fiber is randomly generated as: y2 = y1 + Ln·cos(angle2)·sin(angle1),

[0173] The Z coordinate of the end point of each fiber is randomly generated as: z2=z1+Ln·sin(angle2),

[0174] 1.5. Fiber coordinate adjustment

[0175] After all the fibers are placed, their starting point coordinates and end point coordinates are determined. When their starting point coordinates and end point coordinates exceed the minimum placement boundary of the placement area, their coordinates are automatically corrected to be 1 mm inwardly offset from the minimum placement boundary. The calculation formula is as follows:

[0176] x1=x-min+0.001,

[0177] y1=y-min+0.001,

[0178] z1=z-min+0.001,

[0179] x2=x-min+0.001,

[0180] y2=y-min+0.001,

[0181] z2=z-min+0.001,

[0182] When the starting point coordinates and the end point coordinates exceed the maximum delivery boundary of the delivery area, the coordinates are automatically corrected to be offset 1 mm inward from the maximum delivery boundary. The calculation formula is as follows:

[0183] x1=x-max-0.001,

[0184] y1=y-max-0.001,

[0185] z1=z-max-0.001,

[0186] x2=x-max-0.001,

[0187] y2=y-max-0.001,

[0188] z2=z-max-0.001.

[0189] 1.6. Determination of fiber and steel bar intrusion

[0190] After all the fibers are placed and processed, the intrusion between the fibers and the steel bars is determined, and the starting coordinates POINT-P1 (x1, y1, z1) and the end coordinates POINT-P2 (x2, y2, z2) of the first fiber are extracted, and the starting coordinates POINT-A (X G 1,Y G 1,Z G 1) The corresponding end point coordinates POINT-B (X G 2,Y G 2,Z G 2) When the fiber and the steel bar intrude and intersect in the matrix space, the shortest distance from the coordinates of the two end points of the fiber to the direction vector of the steel bar is calculated respectively. The calculation formula is as follows:

[0191]

[0192]

[0193]

[0194]

[0195]

[0196] Calculate the two intersection points of the shortest distance vector and the steel bar direction vector. The calculation formula is as follows:

[0197]

[0198]

[0199] After finding the midpoint coordinates C of the two intersection points, use the midpoint coordinates C to calculate the shortest distance Dist from the midpoint coordinates to the fiber. The calculation formula is as follows:

[0200]

[0201]

[0202]

[0203]

[0204]

[0205]

[0206]

[0207]

[0208] Finally, the minimum value among Dist, Dist1, and Dist2 is taken as the shortest distance from the fiber to the steel bar. By judging the size relationship between it and the sum of the cross-sectional radius of the fiber steel bar, it is decided whether to delete the fiber and regenerate it. After completing the judgment of the intrusion relationship between the first fiber and the first steel bar in the matrix g_node1 and g_node2, the intrusion relationship between the first fiber and all the remaining steel bars in g_node1 and g_node2 is judged cyclically. After completion, the intrusion relationship between the second fiber and all the steel bars in g_node1 and g_node2 is judged until the intrusion judgment of all fibers and all steel bars is completed. The newly generated fiber needs to re-judge whether it has intrusion with each steel bar in g_node1 and g_node2 until all fibers and all steel bars do not intrude and intersect.

[0209] After the fiber placement is completed, the starting point coordinates of the fiber that meets the requirements are saved in end_node1 in matrix form, and the ending point coordinates of the fiber are saved in end_node2 in matrix form.

[0210] Step 2: After completing all the required fiber placement and steel bar layout, arrange and number the coordinate information of the fibers and steel bars, convert their endpoint coordinates into finite element simulation nodes, renumber and arrange the node information to make it unit information recognizable by the finite element software, and use the fopen function in the MATLAB software to save it in the form of a keyword K file recognizable by the finite element analysis software ANSYS / LS-DYNA.

[0211] 2.1. Convert steel bar and fiber coordinate information into finite element simulation model information

[0212] Node information arrangement: Create a column vector BH4 with a length equal to the number of steel bars O, define its value as 0, and connect BH4 with g_node1 and g_node2 to form a longer node vector. Extract the row number A of end_node1 (i.e. the number of nodes in end_node1) and the row number B of end_node2 (i.e. the number of nodes in end_node2), and create a column vector BH from 1 to A+B+O (the sum of the number of steel bars and the number of fibers) for subsequent node numbering. Arrange the node information in end_node1 and end_node2 in order, and connect the arranged node matrix with BH to form a longer node vector. Initialize a zero matrix NODE of size (3·A+3·O, 5) to store the coordinates and other information of the nodes, and arrange the processed node information in the required order to obtain the total node set.

[0213] Arrange the cell information: Create a column vector BH1 from 1 to A+O, create a column vector BH2 ​​from A+O+1 to A+B+2·O, create a column vector BH3 from A+B+2·O+1 to A+B+3·O for element numbering, create a column vector PART with a length of A+B, define its row values ​​from 1 to A as 100, and define its values ​​from A+1 to A+O as 101. Combine PART, BH1, BH2, and BH3 into an overall cell matrix.

[0214] 2.2. Open the file model.k in write mode, write different model data into the file, add the file header information and format description, and obtain the finite element model file.

[0215] 2.3. Use the finite element analysis software ANSYS / LS-DYNA to directly open the obtained K file, where PART-100 is fiber and PART-101 is steel bar.

[0216] 2.4. Use the finite element analysis software ANSYS / LS-DYNA to open the K file, and establish a homogeneous matrix model by determining the dimensions of the cube concrete, the cube length LX, the cube width LY, and the cube height LZ. Then use the software to save it in the same K file with the fiber and steel bar models.

[0217] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure, characterized in that The steps include: S1. Determine the size and volume of concrete cube; S2. Complete the setting and calculation of steel bar related parameters: according to the parameters of the cubic concrete, set and calculate the steel bar parameters, arrange the first transverse and longitudinal steel bars in the delivery area and determine the coordinates, complete the steel bar arrangement according to the spacing translation, and save the steel bar coordinates; S3, fiber delivery area and related parameter settings: determine the fiber delivery range, determine the delivery quantity according to the selected fiber size parameters, and perform random delivery; S4. Adjustment of fiber placement boundary and determination of fiber invasion with steel bars: Adjust the fiber coordinates beyond the placement boundary. After the adjustment, determine the invasion between the fiber and the steel bars. Delete and regenerate the fiber invading the steel bars until all fibers and all steel bars do not invade or intersect, and save the fiber coordinates. S5: Finite element model establishment: After completing all the required fiber placement and steel bar layout, arrange and number the coordinate information of the fibers and steel bars, convert their endpoint coordinates into finite element simulation nodes, renumber and arrange the node information to make it unit information recognizable by the finite element software, and use the fopen function in the MATLAB software to save it in the form of a keyword K file recognizable by the finite element analysis software ANSYS / LS-DYNA; The matrix finite element model can be generated by finite element software such as ANSYS / LS-DYNA, and the generated homogeneous finite element model can be exported in the form of a k-file.

2. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 1, characterized in that: After all the steel bars are arranged in S2, the starting coordinates of all the horizontal and vertical steel bars are saved in g_node1 in the form of a matrix according to the generation order, and the ending coordinates of all the horizontal and vertical steel bars are saved in g_node2 in the form of a matrix according to the generation order; After the fiber placement is completed in S4, the starting point coordinates of the fibers that meet the requirements are saved in end_node1 in a matrix form, and the ending point coordinates of the fibers are saved in end_node2 in a matrix form.

3. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 2, characterized in that: The steps of node information arrangement in S5 are as follows: create a column vector BH4 with a length equal to the number of steel bars O, define its value as 0, connect BH4 with g_node1 and g_node2 to form a longer node vector; extract the row number A of end_node1 (i.e. the number of nodes of end_node1) and the row number B of end_node2 (i.e. the number of nodes of end_node2), create a column vector BH from 1 to A+B+O (the sum of the number of steel bars and the number of fibers), which is used for subsequent node numbering; arrange the node information in end_node1 and end_node2 in order, and connect the arranged node matrix with BH to form a longer node vector; initialize a zero matrix NODE with a size of (3·A+3·O, 5) to store the coordinates and other information of the nodes, and arrange the processed node information in the required order to obtain the total node set; The steps for arranging the cell information are: create a column vector BH1 from 1 to A+O, create a column vector BH2 ​​from A+O+1 to A+B+2·O, create a column vector BH3 from A+B+2·O+1 to A+B+3·O for element numbering, create a column vector PART with a length of A+B, define its row values ​​from 1 to A as 100, define its values ​​from A+1 to A+O as 101, and combine PART, BH1, BH2, and BH3 into an overall cell matrix.

4. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 3, characterized in that: In S1, the length of the concrete cube is LX, the width of the cube is LY, and the height of the cube is LZ, so the volume of the concrete is: V = LX·LY·LZ; In S2, the length of the steel bars in the X-axis and Y-axis directions is calculated according to the thickness of the concrete cover in the X-axis, Y-axis and Z-axis directions and the length, width and height of the cube in the delivery area; the spacing between the transverse and longitudinal steel bars is calculated according to the number of transverse and longitudinal steel bars arranged; The length of the steel bars is: G-lx=LX-2 px, G-ly=LY-2·py, Among them, px is the thickness of the concrete cover in the X-axis direction, py is the thickness of the concrete cover in the Y-axis direction, G-lx is the length of the steel bar in the X-axis direction, and G-ly is the length of the steel bar in the Y-axis direction; The number of longitudinal reinforcements is nx, the number of transverse reinforcements is ny, and the spacing between reinforcements is: JX=G-lx / (nx-1), JY=G-ly / (ny-1), Among them, JX is used to determine the longitudinal reinforcement spacing, and JY is the transverse reinforcement spacing.

5. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 4, characterized in that: In S2, the starting coordinates of the first transverse reinforcement are first specified in the placement area, the ending coordinates of the first reinforcement are calculated using the reinforcement-related parameters, the three coordinates of the reinforcement in the Cartesian coordinate system are saved, the starting coordinates and ending coordinates of the first transverse reinforcement are translated, and the starting coordinates and ending coordinates of the second transverse reinforcement are obtained, until the arrangement of the transverse reinforcement is completed. The starting point coordinates of the transverse reinforcement (X1 g , Y1 g , Z1 g ) is calculated as follows: X1 g =px, Y1 g =py+JY·(i-1)i∈[1,ny], Z1 g =pz, Transverse reinforcement end point coordinates (X2 g , Y2 g , Z2 g ) is calculated as follows: X2 g =px+G-lx, Y2 g =py+JY·(i-1)i∈[1,ny], Z2 g =pz, After all transverse reinforcements are arranged, the starting coordinates of the first longitudinal reinforcement are calculated in the delivery area, and the ending coordinates of the first longitudinal reinforcement are calculated using the reinforcement-related parameters. The three coordinates of the reinforcement in the Cartesian coordinate system are saved, and the starting coordinates and ending coordinates of the first longitudinal reinforcement are translated to obtain the starting coordinates and ending coordinates of the second longitudinal reinforcement until the longitudinal reinforcement arrangement is completed. The starting point coordinates of the longitudinal reinforcement (X3 g , Y3 g , Z3 g ) is calculated as follows: X3 g =px+JX·(i-1)i∈[1,nx] Y3 g =py, Z3 g =pz+G-dia, The end point coordinates of the longitudinal reinforcement (X4 g , Y4 g , Z4 g ) is calculated as follows: X4 g =px+JX·(i-1)i∈[1,nx], Y4 g =py+G-ly, Z4 g =pz+G-dia, Among them, pz is the thickness of the concrete cover in the Z-axis direction, and G-dia is the diameter of the steel bar section.

6. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 5, characterized in that: In S3, the minimum and maximum delivery coordinate points of the X, Y and Z axes are first determined, and then the fiber delivery range is determined; After all fibers are randomly placed in S4, the starting point coordinates and the end point coordinates are determined to determine whether they exceed the placement boundary; The formula for calculating the fiber delivery range is as follows: x-min=x0, x-max=x0+Lx1, y-min=y0, y-max=y0+Ly1, z-min=z0, z-max=z0+Lz1, Among them, x0 is the minimum delivery coordinate point of the delivery range on the X axis, y0 is the minimum delivery coordinate point of the delivery range on the Y axis, z0 is the minimum delivery coordinate point of the delivery range on the Z axis, Lx1 is the maximum delivery coordinate point of the delivery range on the X axis, Ly1 is the maximum delivery coordinate point of the delivery range on the Y axis, and Lz1 is the maximum delivery coordinate point of the delivery range on the Z axis.

7. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 6, characterized in that: The calculation formula for the number of fibers m put in S3 is as follows: Where dia is the fiber cross-sectional diameter, ratio is the fiber volume content, and Ln is the fiber length.

8. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 7, characterized in that: The method for determining the starting point and direction vector of the fiber in S3 is as follows: Use the rand function rand(1), which generates a random number between 0 and 1. The formula for calculating the starting point coordinates is as follows: The X coordinate of the starting point of each fiber is randomly generated as: x1 = LX rand (1), The Y coordinate of the starting point of each fiber is randomly generated as: y1 = LY rand (1), The Z coordinate of the starting point of each fiber is randomly generated as: z1 = LZ rand (1), Use angle1 to represent the angle of the direction vector in the xy plane, and angle2 to represent the inclination angle of the direction vector in the zy plane. The calculation formula is as follows: angle1=2·π·rand(1), angle2=2·π·rand(1), angle1 and angle2 represent random angles in the range of 0 to 2π; The fiber end point coordinates are calculated using the starting point coordinates and random angles angle1 and angle2. The calculation formula is as follows: The X coordinate of the end point of each fiber is randomly generated as: x2 = x1 + Ln·cos(angle2)·cos(angle1), The Y coordinate of the end point of each fiber is randomly generated as: y2 = y1 + Ln·cos(angle2)·sin(angle1), The Z coordinate of the end point of each fiber is randomly generated as: z2=z1+Ln·sin(angle2).

9. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 8, characterized in that: After all the fibers are placed, their starting point coordinates and end point coordinates are determined. When their starting point coordinates and end point coordinates exceed the minimum placement boundary of the placement area, their coordinates are automatically corrected to be 1 mm inwardly offset from the minimum placement boundary. The calculation formula is as follows: x1=x-min+0.001, y1=y-min+0.001, z1=z-min+0.001, x2=x-min+0.001, y2=y-min+0.001, z2=z-min+0.001, When the starting point coordinates and the end point coordinates exceed the maximum delivery boundary of the delivery area, the coordinates are automatically corrected to be offset 1 mm inward from the maximum delivery boundary. The calculation formula is as follows: x1=x-max-0.001, y1=y-max-0.001, z1=z-max-0.001, x2=x-max-0.001, y2=y-max-0.001, z2=z-max-0.

001.

10. The method for establishing a microscopic finite element model of a single-layer reinforced ultra-high performance concrete structure according to claim 9, characterized in that: When the fiber and the steel bar are intruded, the starting coordinates POINT-P1 (x1, y1, z1) and the end coordinates POINT-P2 (x2, y2, z2) of the first fiber are extracted, and the starting coordinates POINT-A (x1, y1, z1) of the first steel bar in the matrix g_node1 are extracted. G 1,Y G 1,Z G 1) The corresponding end point coordinates POINT-B (X G 2,Y G 2,Z G 2) When the fiber and the steel bar intrude and intersect in the matrix space, the shortest distance from the coordinates of the two end points of the fiber to the direction vector of the steel bar is calculated respectively. The calculation formula is as follows: Calculate the two intersection points of the shortest distance vector and the steel bar direction vector. The calculation formula is as follows: After finding the midpoint coordinates C of the two intersection points, use the midpoint coordinates C to calculate the shortest distance Dist from the midpoint coordinates to the fiber. The calculation formula is as follows: Finally, the minimum value among Dist, Dist1, and Dist2 is taken as the shortest distance from the fiber to the steel bar. By judging its relationship with the sum of the cross-sectional radius of the fiber steel bar, it is decided whether to delete the fiber and regenerate it. After completing the judgment of the intrusion relationship between the first fiber and the first steel bar in the matrix g_node1 and g_node2, the intrusion relationship between the first fiber and all the remaining steel bars in g_node1 and g_node2 is judged cyclically; After completion, the intrusion relationship between the second fiber and all the steel bars in g_node1 and g_node2 is judged until the intrusion judgment of all fibers and all steel bars is completed; The newly generated fiber needs to re-determine whether it intrudes into each steel bar in g_node1 and g_node2, until all fibers do not intrude or intersect with all steel bars.

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