1. The method is characterized in that the bridge structure section is equivalent to a sheet finite element model, actual measurement strain interpolation of each measurement point position in the section is carried out in a numerical simulation mode to form a whole strain difference value field of the bridge structure section, and then each item of internal force monitoring data of the bridge structure section is obtained by combining a constitutive curve of a bridge structure section material.

2. The method for monitoring the internal force of the cross section of the bridge structure according to claim 1, wherein the method specifically comprises the following steps:

s1: collecting the parameters of the cross section of the bridge structure to be measured, and establishing a sheet finite element model consistent with the parameters of the cross section of the bridge structure;

s2: determining the position of each measuring point in the cross section of the bridge structure in the finite element model of the thin plate, acquiring the strain of each measuring point at each moment, and obtaining a discrete weight function of each measuring point by using a numerical simulation method;

s3: calculating to obtain a strain interpolation field of the bridge structure section at each moment based on the strain of each measuring point at each moment and the discrete weight function;

s4: obtaining a stress field and a strain energy density field of the bridge structure section at each moment by utilizing the strain interpolation field of the bridge structure section at each moment and combining the constitutive curve of the bridge structure section material;

s5: and integrating to obtain the axial force, the bending moment and the strain energy of the bridge structure section at each moment based on the stress field and the strain energy density field of the bridge structure section at each moment.

3. The method for monitoring the internal force of the cross section of the bridge structure according to claim 2, wherein the step S3 specifically comprises:

respectively substituting the strain of each measuring point at each moment into a formulaCalculating to obtain a strain interpolation field of the bridge structure section at each moment;

wherein m is the total number of the measuring points; i is a positive integer and is used for representing the serial number of the measuring point; n is a radical of_iIs a discrete weight function of the measuring point i; epsilon_i,tStrain of a measuring point i at the moment t; d_tA strain interpolation field of the bridge structure section at the moment t; t is a positive integer representingThe time of day.

4. The method for monitoring the internal force of the cross section of the bridge structure according to claim 2, wherein the axial force, the bending moment and the strain energy of the cross section of the bridge structure in the step S5 are specifically as follows:

N＝∑_Aσ_kA_k，M_x＝∑_Aσ_kx_kA_k，M_y＝∑_Aσ_ky_kA_k，E＝∑_Ae_kA_k；

wherein N is the axial force of the cross section of the bridge structure; m_xIs a cross-sectional plane bending moment; x is the number of_kIs the distance from the centroid of the kth unit to the neutral axis of the out-of-plane bending moment; m_yIs a bending moment in a cross section plane; y is_kIs the distance from the centroid of the kth unit to the neutral axis of the in-plane bending moment; e is the strain energy of the cross section; e.g. of the type_kIs the strain energy density of the kth cell; a. the_kThe area of the kth unit in the thin plate finite element model is shown; a is the total area of all units of the finite element model of the thin plate; k is a positive integer and represents the number of the unit in the thin plate finite element model.

5. The method for monitoring the internal force of the cross section of the bridge structure according to claim 2, wherein each measuring point is located on a grid node of the finite element model of the thin plate.

6. The method for monitoring the internal force of the cross section of the bridge structure according to claim 2, wherein the step of obtaining the discrete weight function of each measuring point by using a numerical simulation method in the step S2 is specifically as follows:

s21: applying the plate outer direction displacement of a unit I at a measuring point i in the thin plate finite element model, and applying plate outer direction constraint at the rest measuring points; i is a positive integer and is used for representing the serial number of the measuring point;

s22: obtaining the plate outside direction displacement simulation values of all grid nodes in the thin plate finite element model in a numerical simulation mode, namely obtaining a discrete weight function of the measuring point i;

s23: and repeating the steps S21-S22 until the discrete weight functions of all the measuring points are obtained.

7. The method for monitoring the internal force of the cross section of the bridge structure according to claim 6, wherein the discrete weight function is specifically as follows:

N_i＝{u₁,u₂,...,u_n}；

wherein N is_iIs a discrete weight function of the measuring point i; u. of₁,u₂,...,u_nSimulating the plate outside direction displacement values of a 1 st node, a 2 nd node and an nth node in the thin plate finite element model; and n is a positive integer, and the total number of the grid nodes in the thin plate finite element model is taken.

8. The method for monitoring the internal force of the cross section of the bridge structure according to claim 7, wherein the discrete weight function N is_iIndependent of time, the discrete weight functions of the same measuring point at different moments are the same.

9. A monitoring system for internal force of a bridge structure section is characterized by comprising:

a processor and a memory for storing executable instructions;

wherein the processor is configured to execute the executable instructions to perform the method of monitoring forces within a cross-section of a bridge construction of any of claims 1 to 8.

10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements a method for monitoring forces in a cross-section of a bridge structure according to any one of claims 1 to 8.

Background

A large amount of data can be generated in civil engineering structure experiments and health monitoring, and the data comprises displacement, strain, temperature and other information. However, at present, an effective post-processing method is lacked for data acquired by monitoring a large amount of manpower and material resources, and experimental data of points cannot be expanded to a surface or even to form a displacement/strain field, so that strain data cannot be mined to a stress field or even a structure internal force level. At present, due to the insufficient research on the aspects of data interpolation expansion, data visualization, data deep mining and the like, the potential risks of the structure in the construction and normal use processes are difficult to analyze.

The strain data can reflect the stress state of a certain point of the structure most, and is a direct basis for obtaining the structural configuration and the stress state. And reasonably expanding a plurality of strain data to reflect the stress state of the local part and even the whole structure, thereby having very high scientific research value and engineering application prospect. Therefore, an effective strain monitoring data post-processing method is urgently needed, which carries out interpolation expansion on the cross section strain data and carries out deep mining on the expanded data so as to promote visualization, accuracy and systematization of structure monitoring and stress analysis work and dynamically master the working state of the structure in real time.

Disclosure of Invention

In view of the above, the invention provides a method and a system for monitoring internal force of a bridge structure section, which have the advantages of simple construction process, no limitation on the number and distribution of measurement points, effective reduction of complexity of interpolation, and convenience in popularization and application.

In order to achieve the purpose, the invention adopts the technical scheme that:

according to the first aspect of the invention, the method for monitoring the internal force of the cross section of the bridge structure is provided, the cross section of the bridge structure is equivalent to a sheet finite element model, the actually measured strain interpolation of each measuring point position in the cross section is converted into a strain difference value field of the whole cross section of the bridge structure in a numerical simulation mode, and then each item of internal force monitoring data of the cross section of the bridge structure is obtained by combining a constitutive curve of a material of the cross section of the bridge structure.

Further, the method specifically comprises the following steps:

s1: collecting the parameters of the cross section of the bridge structure to be measured, and establishing a sheet finite element model consistent with the parameters of the cross section of the bridge structure;

s2: determining the position of each measuring point in the cross section of the bridge structure in the finite element model of the thin plate, acquiring the strain of each measuring point at each moment, and obtaining a discrete weight function of each measuring point by using a numerical simulation method;

s3: calculating to obtain a strain interpolation field of the bridge structure section at each moment based on the strain of each measuring point at each moment and the discrete weight function;

s4: obtaining a stress field and a strain energy density field of the bridge structure section at each moment by utilizing the strain interpolation field of the bridge structure section at each moment and combining the constitutive curve of the bridge structure section material;

s5: and integrating to obtain the axial force, the bending moment and the strain energy of the bridge structure section at each moment based on the stress field and the strain energy density field of the bridge structure section at each moment.

Further, the S3 specifically includes:

respectively substituting the strain of each measuring point at each moment into a formulaCalculating to obtain a strain interpolation field of the bridge structure section at each moment;

wherein m is the total number of the measuring points; i is a positive integer and is used for representing the serial number of the measuring point; n is a radical of_iIs a discrete weight function of the measuring point i; epsilon_i,tStrain of a measuring point i at the moment t; d_tA strain interpolation field of the bridge structure section at the moment t; t is a positive integer and is used to indicate time.

Further, the axial force, the bending moment and the strain energy of the cross section of the bridge structure in the S5 are specifically as follows:

N＝∑_Aσ_kA_k，M_x＝∑_Aσ_kx_kA_k，M_y＝∑_Aσ_ky_kA_k，E＝∑_Ae_kA_k；

wherein N is the axial force of the cross section of the bridge structure; m_xIs a cross-sectional plane bending moment; x is the number of_kIs the distance from the centroid of the kth unit to the neutral axis of the out-of-plane bending moment; m_yIs a bending moment in a cross section plane; y is_kIs the distance from the centroid of the kth unit to the neutral axis of the in-plane bending moment; e is the strain energy of the cross section; e.g. of the type_kIs the strain energy density of the kth cell; a. the_kThe area of the kth unit in the thin plate finite element model is shown; a is the total area of all units of the finite element model of the thin plate; k is a positive integer and represents the number of the unit in the thin plate finite element model.

Furthermore, all the measuring points are positioned on the grid nodes of the sheet finite element model.

Further, in S2, the obtaining the discrete weight function of each measurement point by using a numerical simulation method specifically includes:

s21: applying the plate outer direction displacement of a unit I at a measuring point i in the thin plate finite element model, and applying plate outer direction constraint at the rest measuring points; i is a positive integer and is used for representing the serial number of the measuring point;

s22: obtaining the plate outside direction displacement simulation values of all grid nodes in the thin plate finite element model in a numerical simulation mode, namely obtaining a discrete weight function of the measuring point i;

s23: and repeating the steps S21-S22 until the discrete weight functions of all the measuring points are obtained.

Further, the discrete weight function is specifically:

N_i＝{u₁,u₂,...,u_n}；

wherein N is_iIs a discrete weight function of the measuring point i; u. of₁,u₂,...,u_nSimulating the plate outside direction displacement values of a 1 st node, a 2 nd node and an nth node in the thin plate finite element model; and n is a positive integer, and the total number of the grid nodes in the thin plate finite element model is taken.

Further, the discrete weight function N_iIndependent of time, the discrete weight functions of the same measuring point at different moments are the same.

Further, the thickness of the thin plate finite element model influences the distribution of the discrete weight function, and the thinner the thickness of the thin plate finite element model is, the smoother the distribution of the discrete weight function is.

According to a second aspect of the present invention, there is provided a system for monitoring forces in a cross section of a bridge structure, comprising:

a processor and a memory for storing executable instructions;

wherein the processor is configured to execute the executable instructions to perform the above-mentioned method for monitoring the force in the cross section of the bridge structure.

According to a third aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the above-mentioned method for monitoring force in a cross section of a bridge structure.

Compared with the prior art, the method and the system for monitoring the internal force of the cross section of the bridge structure have the following advantages:

(1) the method for monitoring the internal force of the cross section of the bridge structure is simple in construction process and has no limit on the number and distribution of cross section measuring points. The problems of equation solution and optimization are avoided, the complexity of interpolation is effectively reduced, and the method is convenient to popularize and apply;

(2) the stress field and the structural internal force are calculated based on the real constitutive curve of the bridge structural section material, no plane section and linear elasticity assumption exists, and the calculation result is closer to the real situation;

(3) the method fully utilizes all strain data of the cross section, interpolates the strain stress field of the cross section, calculates the internal force of the cross section, progresses layer by layer, reasonably expands the information of strain points to the cross section of the whole bridge structure, and provides direct structural stress state judgment basis for scientific research personnel and engineering experts.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a flow chart of a method of an embodiment of the present invention;

FIG. 2 is a sheet finite element model and a survey point distribution of a bridge structural section according to an embodiment of the present invention;

FIG. 3 is a schematic of a weighting function and strain interpolation of an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating calculation of a stress field of a cross-section of a bridge structure according to an embodiment of the present invention;

FIG. 5a is a schematic diagram of the axial force distribution of a bridge construction section according to an embodiment of the present invention;

FIG. 5b is a schematic diagram illustrating an in-plane bending moment distribution of a cross-section of a bridge structure according to an embodiment of the present invention;

FIG. 5c is a graphical illustration of an out-of-plane bending moment distribution pattern for a bridge structural section in accordance with an embodiment of the present invention;

FIG. 5d is a strain energy distribution pattern of a cross-section of a bridge construction according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.

The terms first, second and the like in the description and in the claims of the present invention are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

A plurality, including two or more.

And/or, it should be understood that, as used herein, the term "and/or" is merely one type of association that describes an associated object, meaning that three types of relationships may exist. For example, a and/or B, may represent: a exists alone, A and B exist simultaneously, and B exists alone.

A method for monitoring internal force of a bridge structure section comprises the following specific technical scheme:

a. establishing a sheet finite element model with a cross section shape, dividing the sheet finite element model into a plurality of units, applying specific boundary conditions, and obtaining a discrete weight function N of each measuring point by a numerical simulation method_i。

b. The strain epsilon of each measuring point at the time t_i,tSubstitution formulaNamely, the section strain interpolation field D can be calculated_tWherein m is the total number of measuring points.

c. Then, according to the constitutive curve sigma of the material, f (epsilon) can obtain the stress field of the cross section, and then the integral e ═ sigma d epsilon of the constitutive curve is carried out to calculate the strain energy density field.

d. Finally, according to the formula N ═ Sigma_Aσ_kA_k，M_x＝∑_Aσ_ky_kA_k，M_y＝∑_Aσ_kx_kA_k，E＝∑_Ae_kA_k(wherein A is_kThe area of the kth cell) to numerically integrate the physical quantity field of the whole section a to calculate the axial force, the in-plane bending moment and the strain energy of the structural section.

Preferably, all the measuring points in step a should be right on the grid nodes of the thin plate, the thickness of the thin plate influences the distribution of the weighting function, and the interpolation is smoother as the thin plate is thinner.

Preferably, the specific boundary condition in step a refers to a weight function N in calculating the ith measurement point_iAt time, the off-plate displacement in units of one is added at point i, and zero is set at the remaining points.

Preferably, the displacement of each node obtained by simulation in step a is a discrete weight function N forming a measuring point i_i＝{u₁,u₂,...,u_j,...,u_nIn which u_jIs the analog value at the jth node, and n is the total number of nodes.

Preferably, the strain in step b is a strain in the direction perpendicular to the cross-section, D_tFor discrete representation of the interpolated field at time t, D_t＝{ε₁,ε₂,...,ε_j,...,ε_n}; and N is_iThe method is a discrete function related to space coordinates, and is irrelevant to time, namely the weight functions of the same measuring point at different moments are the same.

Preferably, the unit of the cross-sectional strain energy in step d is J/m.

Preferably, the ANSYS-APDL language programming is used for realizing automatic cycle constraint, batch output of discrete weight functions, numerical integral calculation of internal force and the like.

Preferably, the cross-sectional strain energy density field is calculated using a numerical integration trapezoidal algorithm.

Example (b): dumbbell-shaped concrete filled steel tube bridge arch rib section strain monitoring

The flow chart of this embodiment is shown in fig. 1. Firstly, measuring material parameters and specific parameters of the section of the concrete bridge arch rib, and establishing a dumbbell-shaped sheet finite element model by using large-scale general software ANSYS. From the measurement results, it was found that the steel pipes had a diameter of 50mm and a wall thickness of 4mm, that the centers of the two steel pipes were spaced apart by 140mm, and that the thickness of the plate was 1mm, as shown in FIG. 2. Dividing the concrete part in the pipe into Shell 181 units, and setting the elastic modulus of the material to be 28 GPa; the steel pipe part is divided into Beam 188 units, and the elastic modulus of the material is set to be 200 GPa. In the construction process of the weight function, large deformation and elastoplasticity are not considered, and only the weight functions of different nodes can linearly superpose and calculate the strain field of the unit.

First, a weight function at node 1 is constructed as an example. According to the construction property of the weight function, z-direction unit displacement is added at the node 1, and z-direction fixed constraint is added at other nodes. In addition, in order to limit the rigid body displacement in other directions of the plate, constraints in the x direction and the y direction are added at the node 1, and a constraint in the y direction is added at the node 2. Then, static analysis is carried out, and the obtained z-direction displacement field is the discrete weight function N₁＝{u₁,u₂,...,u_k,...,u_nAs shown in fig. 3.

Similarly, other discrete weighting functions N may be obtained_i(i 1,2, …,8), and then the numerical value Ui of each sample point is substituted into the formulaAn interpolated field of plate out-of-plane displacement can be obtained as shown in fig. 3.

Then, by using constitutive curves of steel and concrete, respectively, a corresponding stress can be obtained from the strain of the node, and a cross-sectional stress field can be obtained, as shown in fig. 4. Similarly, a cross-sectional strain energy density field can be obtained, which is not shown here.

After the stress field and the strain energy density field of the cross section are obtained, the cross section can be integrated to obtain the axial force, the bending moment, the strain energy density, the value and the like of the cross section (the axial force pressure is defined as positive tension, and the bending moment tension side is defined as positive pressure side), and the calculation formula is as follows:

in the formula F, M_yE represents axial force, bending moment and strain energy of the cross section, and E represents strain energy density of each node of the cross section. After the internal force of each section is calculated through numerical integration, an internal force change mode diagram of each measured section of the circular steel tube concrete arch under each load step can be obtained. Fig. 5 a-5 d are diagrams showing the variation modes of axial force, in-plane bending moment, out-of-plane bending moment and strain energy of different cross sections respectively.

The other types of bridges are the same as the method described in this embodiment, and the cross-sectional shapes and parameters of the bridges are different only when the finite element model is established, but the thin plate finite element models are adopted, so that the details are not repeated.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.