JPH11259543A - Structure analysis system and record medium recorded with structure analysis program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure analysis system capable of shortening calculation time and improving the reliability of a solution without causing the dispersion of the solution or indicating instable actions and without the need of setting a parameter for specifying calculation conditions, and to provide a recording medium in which a structure analysis program is recorded. SOLUTION: This system is provided with a distortion computing means S12 for computing the distortion of respective structure members from the equation of motion of the respective structure members, a detection means S14 for detecting in which structure member distortion/stress characteristics change at the earliest point of time and a change means S18 for changing the distortion/stress characteristic value of the equation of the motion for the structure member for which the change is detected. Thus, the dispersion of the solution is not generated, the instable action is not indication, the need of setting the parameter for specifying the calculation conditions is eliminated, the calculation time is shortened and further, the reliability of the solution is prevented from lowering due to the accumulation of calculation errors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structural analysis system and a recording medium on which a structural analysis program is recorded, and more particularly, to a structural analysis system for analyzing an elasto-plastic problem of structural analysis and a recording medium on which a structural analysis program is recorded.

[0002]

2. Description of the Related Art Hitherto, systems for analyzing the structure of buildings such as bridges have been developed. In structural analysis of a bridge or the like, it is necessary to analyze an elasto-plastic problem in which a load applied to a material exceeds a yield point of the material and enters a plastic deformation region from an elastic deformation region. Conventional structural analysis systems perform structural analysis using a convergence method (Newton's method) or a load increment method. When analyzing the elasto-plastic problem, the curvature-bending moment characteristic of the structural member has a smaller inclination in the plastic deformation region than in the elastic deformation region, and the analysis must be performed accordingly.

In the convergence method, when a load is applied to the structural member at once and the curvature of the structural member becomes a plastic deformation region, the bending moment obtained by the inclination in the elastic deformation region is corrected and the plastic deformation region is corrected. Is a method of obtaining the inclination at.
The load increment method is a method of approximating the curvature-bending moment characteristic of a structural member from an elastic deformation region to a plastic deformation region by sequentially increasing a small amount of load instead of applying the load at one time. It is.

[0004]

The conventional structural analysis system using the convergence method is generally used because the calculation time is relatively short and the name recognition is high. Depending on the calculation conditions such as the above, the solution may vary or exhibit unstable behavior, and the solution may not be obtained. In order to prevent this and obtain a solution with stable behavior,
There has been a problem that specialized know-how is required for setting parameters for specifying the above calculation conditions.

Although the conventional structural analysis system using the load increment method can always obtain a solution, the calculation time is long because the load is finely divided and the calculation is performed for each of them. The smaller the value is, the larger the calculation error becomes, and the accumulated errors increase the reliability of the solution. Also,
There has been a problem that specialized know-how is required for setting parameters for specifying calculation conditions.

The present invention has been made in view of the above points, does not cause dispersion of solutions or exhibit unstable behavior, does not require setting parameters for designating calculation conditions, and has a short calculation time. An object of the present invention is to provide a structural analysis system for improving the reliability of a solution and a recording medium on which a structural analysis program is recorded.

[0007]

According to a first aspect of the present invention, there is provided a structural analysis system for performing a structural analysis when an external force is applied to a structure composed of a plurality of elasto-plastic structural members. A strain calculating means for calculating a strain of each of the structural members from an equation of motion of each of the structural members constituting the structure in a state where an external force is applied to the structure, and a strain-strain based on a strain-stress characteristic of each of the structural members. Detecting means for detecting which structural member changes strain-stress characteristics at the earliest point in time, and an external force prior to the external force at the time when the structural member whose change is detected by the detecting means is detected. And a change means for changing a strain-stress characteristic value of the equation of motion with respect to the above. A strain calculation by the strain calculation means, a detection of a change in the strain-stress characteristic by the detection means, and a distortion of the motion equation by the change means. It repeats the change of force characteristic value to obtain a hysteresis characteristic of the respective structural member.

As described above, the distortion calculation by the distortion calculation means,
The detection means changes the strain-stress characteristics and the change means repeatedly changes the strain-stress characteristics of the equation of motion to obtain hysteresis characteristics for each structural member. It is not necessary to set parameters for specifying calculation conditions such as the number of convergences, the number of time divisions, and the convergence error, and the strain-stress characteristics (rigidity) of any structural member in one operation. Since the behavior of the structure during the period until changes can be determined, the calculation time is shortened,
It is possible to prevent the accumulation of calculation errors from lowering the reliability of the solution.

According to a second aspect of the present invention, in order to perform a structural analysis when an external force is applied to a structure composed of a plurality of elasto-plastic structural members, the external force is applied to the structure. A strain calculating means for calculating the strain of each of the structural members from the equation of motion of each of the structural members constituting the structure in an added state; and a strain-stress characteristic for each of the structural members, Detecting means for detecting whether the structural member changes strain-stress characteristics at the earliest time point, and the equation of motion for the external force from the external force at the time point is detected for the structural member whose change is detected by the detecting means. Changing means for changing the strain-stress characteristic value; strain calculation by the strain calculating means; detecting the change in the strain-stress characteristic by the detecting means; and changing the strain-stress characteristic value of the equation of motion by the changing means. Repeating said computer-readable recording medium storing a program for operating to obtain a hysteresis of each structural member.

[0010] By using this recording medium, a structural analysis can be performed, thereby realizing the first aspect of the present invention.

[0011]

FIG. 1 is a block diagram showing an embodiment of a structural analysis system according to the present invention. In the figure, a central processing unit (CPU) 10 has an input device 20 via a bus 15,
Each of the storage device 30, the display device 40, and the printing device 50 is connected. The keyboard 2 is used as the input device 20
1, a mouse 22, a scanner 23, and the like. The storage device 30 includes a RAM 31, a ROM 32, a hard disk device 33, a flexible disk device 34, and a CD.
A ROM device 35 and the like are provided. The structure analysis program for the structure analysis of the present invention is recorded on, for example, a CD-ROM. The CPU 10 reads and executes various processing programs from the storage device 30, stores the results in the storage device 30, displays the result on the display device 40, prints out the data using the printing device 50, and outputs the result. The storage device 30 also stores various libraries in addition to various processing programs.

FIG. 2 is a flowchart of a first embodiment of a structural analysis process executed by the structural analysis system of the present invention.
Here, a description will be given assuming that static analysis of a structure including N structural members is performed. In addition, the curvature-bending moment characteristics as the strain-stress characteristics of each of the N structural members are known in advance. In the figure, it sets the load vector F and the load vector F ₀ of an external force in step S10.
The load vector F ₀ has an initial value of 0, and the load vector F is a finally applied load. This load vector F ₀ (=
Time dt is required to change from 0) to the load vector F.

Next, at step S12, the relative response displacement vector U is obtained by substituting the load vector F into the equation of motion shown in the equation (1).
The section force vector S is obtained using the equation. The cross section vector S includes a bending moment m as a stress. Further, the curvature φ as distortion is obtained from the equation (3). F = K · U (1) S = Ks · U (2) φ = m / (E · I) (3) where K is a rigid matrix, Ks is a stress matrix, and E is Young. The coefficient is determined by the material of the structural member, and I is the second moment of area determined by the structure. The above calculation of the curvature φ is performed for each of the N structural members.

Next, in step S14, it is determined which of the N structural members has the curvature-bending moment characteristic (rigidity) that changes at the earliest time, and what is the load vector Fi at that time ti. Is calculated. Thereafter, in step S16, it is determined whether a stiffness change point at which the curvature-bending moment characteristic (stiffness) changes is found in any of the N structural members, and if a stiffness change point is found, step S18 is performed. in setting the load vector Fi to load vector F _0, the curvature at the earliest time - bending curvature corresponding stiffness matrix K of structural members moment characteristics change - change in accordance with the bending moment characteristic, the process proceeds to step S12.

Thus, the load vector F ₀ (=
The curvature φ of the N structural members in the change from Fi) to the load vector F is calculated, and the curvature-bending moment characteristic (rigidity) changes at the earliest point in any of the N structural members. Then, the rigidity matrix K of the structural member is changed. This step S12 to S1
By repeating the processing in step 8, it is possible to obtain the hysteresis characteristics of the structure including the N structural members until the load vector F is applied.

As described above, the curvature φ of the N structural members is calculated by multiplying the load vector F, and the curvature-bending moment characteristic (rigidity) of the N structural members at the earliest point is determined. In order to find out whether it changes or not, and change the stiffness matrix K of the structural member and repeat the calculation,
Unlike the conventional convergence method, the solution does not vary or exhibit unstable behavior, and there is no need to set parameters for specifying calculation conditions such as the number of times of convergence, the number of time divisions, and the convergence error.

In addition, since the behavior of the structure during the period until the curvature-bending moment characteristic (rigidity) of any one of the structural members changes can be determined by one calculation, the calculation time is longer than that of the conventional load increment method. , The calculation error does not accumulate and the reliability of the solution does not decrease, the accuracy of analysis is improved, and there is no need to set parameters for specifying calculation conditions.

FIG. 3 shows a flowchart of a second embodiment of the structural analysis processing executed by the structural analysis system of the present invention.
Here, a dynamic analysis of a structure composed of N structural members is performed. In addition, the curvature-bending moment characteristics as the strain-stress characteristics of each of the N structural members are known in advance. In the figure, in step S110, an acceleration vector ddα and an acceleration vector ddα ₀ as external forces are set. The acceleration vector ddα ₀ has an initial value of 0, and the acceleration vector ddα is the finally applied acceleration.

Next, in step S112, a relative response displacement vector U is obtained by substituting the acceleration vector ddα into the equation of motion shown in equation (4), and a sectional force vector U is obtained from the relative response displacement vector U using equation (2). Find S. The cross section vector S includes a bending moment m as a stress. Further, the curvature φ as distortion is obtained from the equation (3).

M · ddU + C · dU + K · U = −M · ddα (4) S = Ks · U (2) φ = m / (E · I) (3) where M is a mass matrix, C is the damping matrix, ddU is the relative response acceleration vector,
dU is a relative response speed vector, K is a stiffness matrix, Ks is a stress matrix, E is a Young's modulus determined by a material of a structural member, and I is a second moment of area determined by a structure. The above calculation of the curvature φ is performed for each of the N structural members.

Next, in step S114, it is determined which one of the N structural members changes its curvature-bending moment characteristic (rigidity) at the earliest point in time.
Is calculated as the acceleration vector ddαi. Thereafter, in step S116, it is determined whether a stiffness change point at which the curvature-bending moment characteristic (stiffness) changes is found in any of the N structural members, and if a stiffness change point is found, step S18 is performed. in setting the acceleration vector ddαi the acceleration vector Ddarufa _0, curvature at the earliest time - bending curvature corresponding stiffness matrix K of structural members moment characteristics change - change in accordance with the bending moment characteristic, the process proceeds to step S112.

Thus, the next time the acceleration vector ddα
The calculation of the curvature φ of the N structural members in the change from ₀ (= ddαi) to the acceleration vector ddα is performed, and which of the N structural members has the curvature −
Find out whether the bending moment characteristic (rigidity) changes, and change the rigidity matrix K of the structural member. By repeating the processing of steps S112 to S118, it is possible to obtain the hysteresis characteristics of the structure including the N structural members until the acceleration vector ddα is applied.

In this embodiment, the plasticized structural members 70 and the non-plasticized structural members 72 and 74 shown in FIG.
A rigid frame structure model consisting of, for example, applied acceleration vector ddα such as an earthquake, the structural member 72 as shown in FIG. 4 (B) from the time t ₀ after the time dt is described as being plasticized. Here, the structural member 74 is treated as a rigid body.

At time t ₀ , the curvature-bending moment characteristic of the plasticized structural member 70 in the state shown in FIG. 4A is shown in FIG. 5A, and the plasticized state in the state shown in FIG. FIG. 6 (A) shows the curvature-bending moment characteristics of the structural member 72 that does not exist. Here, the acceleration vector ddα
When applied, in the calculation of the first, the structural member 70 is the radius of curvature represented by broken line arrow in FIG. 5 (B) by a rigid matrix K ₃ - shows the bending moment characteristics. In addition, * mark shows a starting position. At the same time, the structural member 72 is
Curvature represented by broken line arrow in FIG. 6 (B) by ₁ - shows the bending moment characteristics. The structural member 72 at time t ₁
Reaches the rigidity change point at which the curvature-bending moment characteristic (rigidity) changes.

Therefore, in the next operation, the rigidity matrix of the structural member 72 is changed to K ₂ . Thus, the curvature structural member 70 is represented by broken line arrow in FIG. 5 (C) by a rigid matrix K ₃ - shows the bending moment characteristics. At the same time, the structural member 72 the curvature represented by broken line arrow in FIG. 6 (C) by a rigid matrix K ₂ - shows the bending moment characteristics. The curvature of the structural member 70 at the time point t ₂ - to reach the bending moment characteristics (stiffness) of varying stiffness change point (yield point).

Therefore, in the next operation, the rigidity matrix of the structural member 70 is changed to K ₂ . Thus, the curvature structural member 70 is represented by broken line arrow in FIG. 5 (D) by a rigid matrix K ₂ - shows the bending moment characteristics. At the same time, the structural member 72 the curvature represented by broken line arrow in FIG. 6 (D) by a rigid matrix K ₂ - shows the bending moment characteristics. The structural member 70 from the time t ₀ after the time dt, the curvature represented by the solid line in FIG. 5 (E) - leading to the eventual shows the bending moment characteristics. At the same time, the structural member 72
Shows the curvature-bending moment characteristic indicated by the solid line in FIG. FIGS. 5A to 5E show the hysteresis characteristics of the structural member 70, and FIGS. 6A to 6E show the hysteresis characteristics of the structural member 72.

As described above, the curvature φ of the N structural members is calculated by multiplying the acceleration vector ddα, and the curvature-bending moment characteristic (rigidity) of the N structural members at the earliest point in time is calculated. Since the change is found and the stiffness matrix K of the structural member is changed and the calculation is performed repeatedly, the convergence method does not produce a dispersion or unstable behavior as in the conventional convergence method. There is no need to set parameters that specify calculation conditions such as the number of divisions and the convergence error.

Further, since the behavior of the structure during the period until the curvature-bending moment characteristic (rigidity) of any structural member changes can be determined by one calculation, the calculation time is longer than that of the conventional load increment method. , The calculation error does not accumulate and the reliability of the solution does not decrease, the accuracy of analysis is improved, and there is no need to set parameters for specifying calculation conditions.

When performing a structural analysis of an earthquake-resistant structure,
By continuously applying and analyzing the acceleration vector ddα of the seismic wave, a hysteresis characteristic as shown in FIGS. 5 and 6 of each structural member is obtained. Steps S12 and S112 correspond to distortion calculation means, steps S14 and S114 correspond to detection means, and steps S18 and S118 correspond to change means.

[0030]

As described above, the first aspect of the present invention provides
In order to obtain the hysteresis characteristic of each structural member, the distortion calculation by the distortion calculation means, the detection of the change in the strain-stress characteristic by the detection means, and the change of the distortion-stress characteristic value of the equation of motion by the change means are repeated. There is no need to set parameters that specify calculation conditions such as the number of times of convergence, the number of time divisions, and the convergence error.
A single operation can determine the behavior of a structure until the strain-stress characteristics (rigidity) of any of the structural members change, shortening the calculation time, accumulating calculation errors, and improving the reliability of the solution. Can be prevented from decreasing.

Further, by using the recording medium according to the second aspect, structural analysis can be performed, thereby realizing the invention according to the first aspect.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a structural analysis system according to the present invention.

FIG. 2 is a flowchart of a first embodiment of a structural analysis process executed by the structural analysis system of the present invention.

FIG. 3 is a flowchart of a second embodiment of the structure analysis processing executed by the structure analysis system of the present invention.

FIG. 4 is a diagram showing a ramen structure model subjected to a structure analysis by the structure analysis system of the present invention.

FIG. 5 is a diagram illustrating hysteresis characteristics of a structural member 70.

FIG. 6 is a diagram illustrating hysteresis characteristics of a structural member 72.

[Explanation of symbols]

 Reference Signs List 10 central processing unit (CPU) 20 input device 21 keyboard 22 mouse 23 scanner 30 storage device 31 RAM 32 ROM 33 hard disk device 34 flexible disk device 35 CD-ROM device 40 display device 50 printing device 70 to 74 structural members

Claims (2)

[Claims] 1. A structural analysis system for performing structural analysis when an external force is applied to a structure composed of a plurality of elasto-plastic structural members, wherein the structure has an external force applied to the structure. A strain calculating means for calculating the strain of each of the structural members from the equation of motion of each of the structural members, and which structural member has the earliest strain corresponding to the strain from the strain-stress characteristic of each of the structural members. Detecting means for detecting whether the stress characteristic changes; and changing the distortion-stress characteristic value of the equation of motion with respect to the external force from the external force at the time of the detection with respect to the structural member in which the change is detected by the detecting means. A change means, a strain calculation by the strain calculation means, a change in strain-stress characteristic detected by the detection means, and a change of the equation of motion by the change means are repeated, and the hysteresis characteristic of each of the structural members is repeated. Structure analysis system and obtaining. 2. The computer according to claim 1, wherein the computer is configured to perform a structural analysis when an external force is applied to a structure including a plurality of structural members having elasto-plasticity. A strain calculating means for calculating a strain of each of the structural members from an equation of motion of each of the structural members constituting the object; and a structural member corresponding to the strain from the strain-stress characteristic of each of the structural members at the earliest time point. Detecting means for detecting whether the strain-stress characteristic changes; and changing the strain-stress characteristic value of the equation of motion with respect to the external force from the external force at the time of the detection for the structural member for which the change is detected by the detecting means. Changing means for performing the strain calculation in the strain calculating means, distortion in the detecting means, detection of a change in stress characteristics, and distortion in the equation of motion in the changing means.
A computer-readable recording medium on which a program for causing a function to obtain a hysteresis characteristic for each of the structural members by repeatedly changing a stress characteristic value is recorded.