A rapid definition method for bridge launching construction stages based on the MIDASMCT command

Abstract

The application discloses a kind of based on MIDAS MCT command bridge incremental launching construction phase fast definition method, including using MIDAS software to construct bridge finite element model;Extract beam body node coordinates;Bridge overall coordinate system is built, to generate and obtain incremental launching support node coordinates;Current beam body incremental launching distance is calculated;Bridge incremental launching beam body node coordinates are updated;Support beam body support coordinate is generated;The support coordinate consistent with the relative position of beam body node is generated;Determine support node number;Vertical support node number is defined on each node of beam body;The definition of entire incremental launching construction phase is completed.The application is with the aid of MIDAS MCT command, for any complex bridge structure, any long distance incremental launching process, can be programmed, fast construction phase definition is completed, avoids manual support position judgment, node boundary definition, boundary group activation and passivation etc. Operation, especially suitable for incremental launching structure complex, incremental launching support arrangement various incremental launching process analysis.

Description

Technical Field

[0001] This invention belongs to the technical field of bridge construction, specifically relating to a method for rapidly defining the bridge jacking construction stage based on the MIDAS MCT command. Background Technology

[0002] The incremental launching method is a widely used bridge construction method. It involves casting or assembling the bridge beams section by section on the embankment behind the abutments, and then using a launching device to push them longitudinally through temporary supports until they are in place. Incremental launching does not disrupt traffic below the bridge, does not require large lifting equipment, and involves no high-altitude work, making it particularly suitable for the construction of extra-long span urban bridges, long approach bridges, or grade-separated intersections. Because the bridge is constructed on a prefabrication site, construction quality and schedule are easily guaranteed.

[0003] However, during the jacking process, the support state of the bridge changes continuously, causing the stress on the bridge to change dynamically. This requires stress analysis of the dynamically changing bridge to verify whether the strength, stiffness and stability of the bridge meet the requirements during the jacking process.

[0004] Currently, finite element analysis (FEM) software is commonly used to first establish a finite element model of the bridge. Then, construction stages are defined based on different support states for different jacking distances. Finally, stress analysis is performed, and the results are extracted for verification. MIDAS is a commonly used bridge analysis software, and the above process is often implemented within MIDAS. After establishing the finite element model in MIDAS, construction stages need to be defined based on the support state of the bridge at each jacking distance. Each construction stage definition generally requires four operations: first, determining the beam support positions at each jacking distance; then, generating and selecting nodes representing the beam support positions; next, defining boundary conditions for these nodes and assigning boundary groups; finally, activating the boundary groups representing the current support state while deactivating the boundary groups activated in the previous construction stage, thus completing the definition of one construction stage.

[0005] As can be seen, defining just one construction stage involves four operations, which is quite cumbersome. However, the total jacking distance of a bridge is generally long (ranging from tens to thousands of meters), while the distance of a single jacking is often short (generally less than 1 meter). If a stress analysis is performed for each jacking, a large number of construction stages need to be defined, which is very time-consuming. For example, if the total jacking distance of a bridge is 500 meters and each jacking distance is 0.5 meters, then a total of 1000 (500m / 0.5m) construction stages need to be defined to complete the analysis of the entire jacking construction stage. In actual engineering, to save time, stress analysis is often performed only on critical construction stages, such as the maximum cantilever construction stage. However, these critical construction stages are not necessarily the most unfavorable stress state for the structure. Therefore, this kind of stress analysis based on individual construction stages to represent the entire jacking process carries the risk of unsafe calculation results. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned shortcomings of existing technologies by providing a rapid definition method for bridge jacking construction stages based on the MIDAS MCT command. This method solves the problems of cumbersome construction stage definitions and unsafe calculation results in existing jacking construction stress analysis. The MCT command is a built-in modeling tool in the MIDAS software. Using the MCT command, users can programmatically perform operations such as model creation, load application, boundary definition, and construction stage definition.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A rapid definition method for bridge jacking construction stages based on MIDAS MCT commands includes the following steps:

[0009] S1. Construct a finite element model of the bridge using MIDAS software;

[0010] S2. Based on the bridge finite element model, extract the beam node coordinates x. n ;

[0011] S3. Using the position of the bridge beam before jacking as the reference state, construct the overall coordinate system X of the bridge to generate the coordinates x of the jacking support nodes. s ;

[0012] S4. Calculate the current jacking distance Δx of the beam based on the total jacking distance and jacking step distance;

[0013] S5. Based on the current beam launching distance Δx, obtain the updated coordinates of the bridge launching beam nodes.

[0014] S6. Traverse the node coordinates x of the bridge jacking support. sBased on the updated coordinates of the bridge jacking beam nodes... Generate the coordinates x′ of the support beam bracket. s ;

[0015] S7. Based on the coordinates x′ of the supporting beam bracket s Based on the current beam jacking distance Δx, generate support coordinates x″ that are consistent with the relative positions of the beam nodes. s ;

[0016] S8. Traverse the coordinates x of the beam nodes. n The element is found to be related to the bracket coordinate x″. s The coordinates of the node with the smallest difference between the elements are the support node numbers.

[0017] S9. Define the vertical support node number at each node of the beam;

[0018] S10. Repeat steps S1 to S9 to define the vertical support node numbers for the next stage of the jacking construction and delete the vertical support node number definitions from the previous stage until the definition of the entire jacking construction stage is completed.

[0019] Furthermore, step S1 specifically includes:

[0020] A finite element model of the bridge was constructed using MIDAS software, with the direction of bridge jacking as the positive x-axis; and boundary group names for the construction stage were defined in the bridge finite element model.

[0021] Furthermore, step S2 specifically includes:

[0022] Extract the node numbers and x-coordinates of all nodes in the entire incremental launching beam from the finite element model of the bridge, and store them in x n In the matrix;

[0023] And using the x-coordinate as a reference, sort the matrix x in ascending order. n Sort the two columns of data and assign the sorted data to x. n :

[0024]

[0025] Where, x n It is a K×2 matrix, where K is the number of nodes; 2 represents two columns, the first column stores the node number, and the second column stores the x-coordinate corresponding to the node number.

[0026] Furthermore, in step S3, the coordinates of the jacking support node x in the bridge's overall coordinate system X are... s for:

[0027]

[0028] Where M represents the number of jacking supports.

[0029] Furthermore, the current beam jacking distance Δx in step S4 is:

[0030] Δx = kδ (k = 0, 1, 2, ... N) sgjd )

[0031] Where δ is the jacking step distance and k is the cumulative number of jackings of the beam;

[0032] N sgjd The total number of construction phases is:

[0033] N sgjd =int(L tol / δ)

[0034] Among them, L tol The total push distance is represented by int(), which is the floor function.

[0035] Furthermore, the updated bridge launching beam node coordinates in step S5 for:

[0036]

[0037] Furthermore, step S6 specifically includes:

[0038] Traverse each element in the coordinates of the bridge launching support nodes judge Does it belong to

[0039] If yes, then the bracket is the supporting beam; if no, it means the beam has passed by or has not reached the bracket; this process continues until all brackets supporting the current beam are selected, generating the bracket coordinates x′. s :

[0040]

[0041] Where m is the number of supports currently supporting the beam, and m≤M.

[0042] Furthermore, the support coordinates x″ in step S7 s for:

[0043]

[0044] Furthermore, step S8 specifically includes:

[0045] For the support coordinate x″ s Each element Traverse the coordinates x of the beam nodes nAll elements in the beam node coordinates x n Find with The node with the smallest difference is the support node.

[0046] Let the node number of this support node be . When the beam is pushed forward by Δx, the support node numbers N are... Δx for:

[0047]

[0048] The rapid definition method for bridge jacking construction stage based on MIDAS MCT command provided by this invention has the following beneficial effects:

[0049] (1) With the help of the MIDAS MCT command, the construction stage definition can be completed in a programmed and rapid manner for any complex bridge structure and any long-distance jacking process, avoiding manual operations such as support position judgment, node boundary definition, boundary group activation and passivation. It is particularly suitable for the analysis of jacking process with complex jacking structure and diverse jacking support layout.

[0050] (2) By using the two parameters δ of the jacking step and k of the cumulative number of jackings of the beam, the jacking process analysis of long-distance bridge jacking construction can be achieved with small step and high precision, thereby capturing the stress state of the bridge throughout the jacking process and avoiding the risk of unsafe calculation results based on individual construction stages representing the entire jacking process. It is particularly suitable for the analysis of bridge jacking process where the single jacking distance is small but the total jacking distance is large. Attached Figure Description

[0051] Figure 1 This is a flowchart of the rapid definition method for the bridge jacking construction stage based on the MIDAS MCT command of the present invention.

[0052] Figure 2 This is the arrangement of the jacking support for the Fujiang Bridge in Example 3.

[0053] Figure 3 This represents the support state when the maximum support reaction force occurs during the entire jacking process in Example 3. Detailed Implementation

[0054] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0055] Example 1

[0056] This embodiment presents a rapid definition method for bridge jacking construction stages based on the MIDAS MCT command, which can quickly define the entire jacking construction stage. (Refer to...) Figure 1 Specifically, it includes the following steps:

[0057] Step S1: Construct a finite element model of the bridge using MIDAS software;

[0058] Specifically, the bridge finite element model is constructed using MIDAS software, with the bridge jacking direction as the positive x-axis; and the boundary group names for the construction stage are defined in the bridge finite element model.

[0059] Step S2: Based on the finite element model of the bridge, extract the x-coordinates of the beam nodes. n ;

[0060] Specifically, assuming the longitudinal direction of the bridge is parallel to the x-axis, and the bridge is being pushed along the positive x-axis, then in the finite element model, the node numbers and x-coordinates of all nodes of the entire jacking beam (including the front and rear guide beams and the main beam, hereinafter referred to as "beam body") are extracted and stored in x... n In the matrix; then, using the x-coordinate as a reference, sort the x coordinates from smallest to largest. n Sort the two columns of data and assign the sorted data to x. n :

[0061]

[0062] Where, x n It is a K×2 matrix, where K is the number of nodes; 2 represents two columns, the first column stores the node number, and the second column stores the x-coordinate corresponding to the node number.

[0063] Step S3: Using the position of the bridge beam before jacking as the reference state, construct the overall coordinate system X of the bridge to generate the coordinates x of the jacking support nodes. s ;

[0064] Specifically, taking the position of the beam before jacking as the reference state, a bridge overall coordinate system X is established. The origin of the bridge overall coordinate system is consistent with that in the finite element model and points in the jacking direction.

[0065] In the X-coordinate system, the coordinates of the jacking support nodes are x s for:

[0066]

[0067] Where M represents the number of jacking supports.

[0068] Step S4: Calculate the current jacking distance Δx of the beam based on the total jacking distance and jacking step distance;

[0069] Specifically, let the total distance of the beam being pushed be L. tol If the jacking step distance is δ, then the entire jacking process requires at least N steps. sgjd Construction phase simulation:

[0070] N sgjd =int(L tol / δ)

[0071] Here, int() is the floor function;

[0072] To ensure analysis accuracy, the length of the beam element is recommended to be less than the defined jacking step distance; for example, the total jacking distance L of a certain bridge tol =100m, jacking step distance δ=0.5m, then the total jacking distance requires defining N. sgjd = 200 construction stages; to ensure analysis accuracy, the length of the main beam unit is recommended to be controlled within 0.5m.

[0073] Let the current jacking distance be Δx, the jacking step distance be δ, and the beam be jacked a total of k times, then:

[0074] Δx = kδ (k = 0, 1, 2, ... N) sgjd )

[0075] When k = 0, Δx = 0, which is the state before the beam is pushed forward.

[0076] Step S5: Based on the current beam launching distance Δx, obtain the updated coordinates of the bridge launching beam nodes.

[0077] In the X-coordinate system, the coordinates of the nodes of the bridge beam during jacking are as follows: for:

[0078]

[0079] Step S6: Traverse the coordinates x of the bridge launching support nodes. s And based on the updated coordinates of the bridge launching beam nodes Generate the coordinates x′ of the support beam bracket. s ;

[0080] Maximum value in the node coordinates of bridge launching beam and minimum value The coordinates of the front and rear ends of the beam are represented by the coordinates of the front and rear ends. The support located between the two ends is the support of the beam. Based on this, the support node of the beam can be determined.

[0081] If yes, then the bracket is the supporting beam; if no, it means the beam has passed by or has not reached the bracket; this process continues until all brackets supporting the current beam are selected, generating the bracket coordinates x′. s :

[0082]

[0083] Where m is the number of supports currently supporting the beam, and m≤M.

[0084] During the construction phase, the bridge finite element model does not actually update the node coordinates with the jacking distance. In other words, no matter how far the actual bridge moves, the coordinates of the bridge finite element model elements and nodes will not change. Therefore, the current support position can only be determined based on the relative positional relationship between the support and the beam.

[0085] Step S7: Based on the coordinates x′ of the supporting beam bracket s Based on the current beam jacking distance Δx, generate support coordinates x″ that are consistent with the relative positions of the beam nodes. s ;

[0086] Specifically, for x′ s Subtracting Δx from all elements yields the support coordinates x″, which correspond to the relative positions of the beam nodes. s :

[0087]

[0088] Step S8: Traverse the coordinates x of the beam nodes n The element is found to be related to the bracket coordinate x″. s The coordinates of the node with the smallest difference between the elements are the support node numbers.

[0089] Specifically, under the premise that the length of the beam element is less than the jacking distance δ, when the jacking distance of the beam is Δx, the method for determining the support nodes is as follows:

[0090] For the support coordinate x″ s Each element Traverse the coordinates x of the beam nodes n All elements in the beam node coordinates x n Find with The node with the smallest difference is the support node.

[0091] Let the node number of this support node be . When the beam is pushed forward by Δx, the support node numbers N are... Δx for:

[0092]

[0093] Step S9: Define the vertical support node number at each node of the beam;

[0094] Step S10: Repeat steps S1 to S9 to find the support nodes at any jacking distance, define the vertical support node number for the next stage of jacking construction, and delete the vertical support node number definition of the previous stage until the definition of the entire jacking construction stage is completed.

[0095] Example 2

[0096] This embodiment provides a device for rapidly defining bridge jacking construction stages based on the MIDAS MCT command. It includes a processor for executing steps S1 to S10 in Embodiment 1. For a bridge model established using the commonly used bridge analysis software MIDASCivil, taking MATLAB as an example, a program for defining jacking construction stages is developed, automatically generating the MIDAS MCT command. The MCT command allows for the programmatic definition of complex and lengthy construction stages. Its main steps are as follows:

[0097] (1) A bridge finite element model (hereinafter referred to as "model") is established using MIDAS software, with the jacking direction being the positive x-axis; the boundary group names of the construction stages are defined in the bridge finite element model; for example, if 80 construction stages need to be simulated throughout the jacking process, then BSTG1, BSTG2, ..., BSTG80 are defined.

[0098] (2) Extract the node numbers and x-coordinates of the beams from the bridge finite element model and store them in a table named node.xlsx. In the current working directory of MATLAB, use the importdata() function to read the data from node.xlsx and assign it to the parameter named cor_nd.

[0099] (3) In the same coordinate system as the bridge finite element model, generate the x coordinates of all supports and assign them to a parameter named cor_zj.

[0100] (4) Based on cor_nd and cor_zj, the proposed method is used to determine the coordinates of the supports for the beam in the current construction stage, and these coordinates are stored in a parameter named Dx_zj. Subtract Δx from each element in Dx_zj to obtain the coordinates of the supports that are consistent with the relative positions of the beam nodes, and store them in a parameter named Xs_2p.

[0101] (5) Based on Xs_2p, determine the support node of the current construction stage and store the node number in the ZZJD parameter.

[0102] (6) Generate the MCT command for the support defined in MIDAS based on ZZJD. This step is completed in MATLAB and requires the fprintf() function. Key command: fprintf(fileID,'%d,001000,BSTG%d\n',ZZJD(i),kk)

[0103] (7) Generate the MCT command that defines the construction stage in MIDAS and store it in the MCT.txt file in the current working path. Key commands are: fprintf(fileID,'NAME=STAGE1,0,YES,NO,NO,5\n'); fprintf(fileID,'ABNDR=BSTG1,ORIGINAL\n').

[0104] (8) In the “MCT command window” of MDIAS, run the MCT command to complete the definition of the jacking construction stage.

[0105] Example 3

[0106] This embodiment uses the method in Embodiment 1 to quickly define the bridge jacking construction stage, taking the Mianyang Science and Technology City Fujiang Bridge as an example.

[0107] The Mianyang Science and Technology City Fujiang Bridge is my country's first inclined steel box girder basket arch bridge, hereinafter referred to as "Fujiang Bridge". The Fujiang Bridge has a main span of 255m, an arch rib inclination of 70°, an in-plane rise of 52m, and a rise-to-span ratio of 1:4.68. The Fujiang Bridge was constructed using an integral beam-arch jacking method, where the main beams, crossbeams, bridge deck, and arch ribs were first assembled on the riverbank, and then a walking-type jacking device was used to push the bridge to its position in the river. The total jacking weight was 14,000t, and the total jacking distance was 288m. To facilitate the jacking, the bridge was equipped with front and rear guide beams, each 35m long, with a total beam length of 255m, and a total jacking beam length of 325m. The Fujiang Bridge has a total of 12 jacking supports, with a support spacing of 47m to 49.8m, arranged as follows: Figure 2 As shown;

[0108] Because the Fujiang Bridge uses a beam-arch integral jacking method, the stress during the jacking stage is more complex than that of simply jacking the beam itself, especially in the beam-arch junction. The main beam must withstand both the support reaction force (upward) and the self-weight of the arch ribs (downward). Therefore, for such a complex system as the Fujiang Bridge, the usual "maximum cantilever state" as the most unfavorable working condition cannot meet the stress analysis requirements of the entire jacking process. A more refined jacking process analysis is necessary.

[0109] Therefore, a finite element model of the bridge was first established using MDIAS software, with the launching support in the model simulated using a unidirectional bearing subjected only to compression. Then, based on the method proposed in Example 1, the program developed in Example 2 was used to generate MCT commands defining construction stages with a step distance of 1m. Finally, the MCT commands were run in MDIAS to complete the definition of 288 launching construction stages for the Fujiang Bridge.

[0110] Based on the analysis of the construction stages with a step distance of 1m, the maximum support reaction force during the jacking process, the support number, and the jacking distance were obtained, as shown in Table 1.

[0111] Table 1 Summary of Maximum Support Reactions During the Pushing Stage

[0112]

[0113] As shown in Table 1, when the beam was pushed 113m, the maximum support reaction force (1452.4t) occurred during the entire pushing process, which happened on the L7 support. At this time, the support state of the beam was as follows: Figure 3 As shown in the figure, the maximum support reaction does not occur in the maximum cantilever state. If the "maximum cantilever state" is taken as the most unfavorable working condition, the calculation results will be biased towards unsafety.

[0114] As can be seen from the content of this embodiment, the present invention can not only quickly define the bridge jacking construction stage and accurately determine the maximum support reaction state, but also determine the maximum bending moment state, maximum shear force state, and the most unfavorable state of the beam-arch joint section for the main beam. It is particularly suitable for the analysis of jacking process with complex jacking structures and diverse jacking support arrangements.

[0115] Although specific embodiments of the invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by a person skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A method for rapidly defining bridge jacking construction stages based on MIDAS MCT commands, characterized in that, Includes the following steps: S1. Construct a finite element model of the bridge using MIDAS software; S2. Based on the bridge finite element model, extract the coordinates of the beam nodes. x n ; S3. Using the position of the bridge beam before it is pushed forward as the reference state, construct the overall coordinate system of the bridge. X To generate the node coordinates of the jacking support. x s ; S4. Calculate the current jacking distance of the beam based on the total jacking distance and the jacking step distance. Δx ; S5. Based on the current beam jacking distance... Δx The updated coordinates of the bridge launching beam nodes are obtained. ; S6. Traverse the node coordinates of the bridge jacking support. x s Based on the updated coordinates of the bridge jacking beam nodes... Generate the coordinates of the supporting beam bracket. ; S7. Based on the coordinates of the supporting beam bracket and the current beam jacking distance Δx Generate support coordinates that are consistent with the relative positions of the beam nodes. ; S8. Traverse the coordinates of the beam nodes. x n The elements are searched for in relation to the coordinates of the support. The coordinates of the node with the smallest difference between the elements are the support node numbers. S9. Define the vertical support node number at each node of the beam; S10. Repeat steps S1 to S9 to define the vertical support node number for the next stage of the jacking construction and delete the vertical support node number definition for the previous stage until the definition of the entire jacking construction stage is completed. The current beam jacking distance in step S4 Δx for: in, δ The pushing step distance, k The total number of times the beam was pushed. ; N sgjd The total number of construction phases is: in, L tol The total push distance is represented by int(), which is the floor function.

2. The method for rapid definition of bridge jacking construction stages based on MIDAS MCT commands according to claim 1, characterized in that, Step S1 specifically includes: A finite element model of the bridge was constructed using MIDAS software, with the bridge jacking direction as the reference point. x The positive axis; and the boundary group name for the construction stage is defined in the bridge finite element model.

3. The method for rapid definition of bridge jacking construction stages based on MIDAS MCT commands according to claim 1, characterized in that, Step S2 specifically includes: Extract the node numbers of all nodes in the entire launching beam from the bridge finite element model. x Coordinates, and store them in x n In the matrix; and with x Using coordinates as a reference, arrange the matrix in ascending order. x n Sort the two columns of data and assign the sorted data to... x n : in, x n for K A 2x2 matrix K This represents the number of nodes; 2 indicates two columns, the first column stores the node number, and the second column stores the corresponding node number. x coordinate.

4. The method for rapid definition of bridge jacking construction stages based on MIDAS MCT commands according to claim 1, characterized in that, In step S3, the bridge's overall coordinate system X Lower jacking support node coordinates x s for: in, M This refers to the number of jacking supports.

5. The method for rapid definition of bridge jacking construction stages based on MIDAS MCT commands according to claim 3, characterized in that, The updated bridge jacking beam node coordinates in step S5 for: 。 6. The method for rapid definition of bridge jacking construction stages based on MIDAS MCT commands according to claim 5, characterized in that, Step S6 specifically includes: Traverse each element in the coordinates of the bridge launching support nodes ,judge Does it belong to ; If yes, then the bracket is the supporting beam; if no, it means the beam has passed by or has not reached the bracket; this process continues until all brackets supporting the current beam are identified, generating the bracket coordinates for the supporting beam. : in, m This represents the number of supports currently supporting the beam. m ≤ M .

7. The method for rapid definition of bridge jacking construction stages based on MIDAS MCT commands according to claim 6, characterized in that, The bracket coordinates in step S7 for: 。 8. The method for rapid definition of bridge jacking construction stages based on MIDAS MCT commands according to claim 7, characterized in that, Step S8 specifically includes: For the coordinates of the support Each element Traverse the coordinates of the beam nodes x n All elements in the beam node coordinates x n Find with The node with the smallest difference is the support node. Let the node number of this support node be . Then the beam is pushed up. Δx At that time, all support node numbers for: 。

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