JP3874657B2 - Piping network seismic strength analysis method and piping network seismic strength analysis device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piping network seismic strength analysis method and a piping network seismic strength analysis device for analyzing seismic strength of a piping network.
[0002]
[Prior art]
In general, city gas and water and sewage piping networks are used to supply public resources such as fuel gas and tap water for general households to consumers in a given area. Inside, it is installed in the form of a complex network like a blood vessel network in the human body. For example, in a city gas piping network, so-called conduits are almost entirely buried underground in a predetermined area under the jurisdiction of a gas supply company, which is generally called a buried pipe. However, there are some places where the conduit is partially exposed to the ground.
[0003]
In order to ensure safety in the event of an earthquake with respect to such a pipe network, the so-called seismic strength of the pipe network against an earthquake and the strength against external forces applied due to fluidization of the ground caused by an earthquake are accurately measured. It is necessary to grasp.
[0004]
In the conventional technology, the probability of damage occurrence corresponding to the magnitude of the earthquake is obtained based on the information on the damage situation obtained in the past earthquake (reported in the past), and based on that, statistically or probabilistically The so-called seismic strength of the piping network was estimated.
[0005]
For example, when the Kobe earthquake occurred, the situation of damage occurring in the piping network in the Kobe Hanshin area was investigated from the viewpoint of piping materials and valve varieties, and the information was statistically processed. The probability of occurrence of damage to the piping network in the event of a major earthquake is determined in advance. When an earthquake of the same scale occurs, the damage rate of the piping caused by the earthquake is obtained based on the predetermined probability of damage occurrence. In addition, the probability of occurrence of damage to the piping network in several other past earthquakes is investigated, and the correlation between the magnitude of the earthquake and the damage rate of the piping network is obtained statistically from these data, and an actual earthquake occurs. At that time, the damage rate of the piping network corresponding to the magnitude of the earthquake that occurred at that time was obtained based on the correlation obtained in advance. Alternatively, set the external force and magnitude of the earthquake motion corresponding to the seismic intensity estimated to occur in the near future, and set the probability of damage to pipes and valves, etc., when such an earthquake occurs. Inferring based on a predetermined damage occurrence probability has been performed.
[0006]
[Problems to be solved by the invention]
However, in the estimation method as described above, the occurrence situation of the piping damage when the earthquake occurs and the earthquake resistance performance of the piping are, for example, “the probability of breakage of the pipe buried in 1970 in Awaji area is 50%” Thus, it can be estimated only probabilistically (or statistically).
[0007]
In addition, since the data on pipe damage caused by past earthquakes is statistically processed to determine the probability of pipe breakage, the scale of the past earthquake and the damage to pipes at that time are not necessarily covered in all cases. A sufficiently large amount of data is not grasped, and the reliability (accuracy or probability) of the obtained probability of breakage is not necessarily sufficient.
[0008]
In addition, since the collection of information related to damage to pipes at the time of an earthquake began in earnest in recent years as a countermeasure against earthquakes, the amount of information (cases) related to damage to pipes is not always sufficient. The current situation cannot be said to be a thing. For this reason, in the prior art, the accuracy of the damage probability of the piping network estimated when an earthquake actually occurs is not necessarily high.
[0009]
For example, in recent years, information on damage to piping in the Kobe earthquake has been obtained, so if an earthquake of the same scale as this Kobe earthquake occurs, it is possible to determine the probability of pipe failure with relatively high accuracy. it is conceivable that. However, since earthquakes that occur in the future are not necessarily the magnitude of or less than the magnitude of the Kobe earthquake, for example, in the estimation of seismic strength for earthquakes that are larger (unprecedented) than the Kobe earthquake, It is difficult to obtain an accurate failure probability.
[0010]
Therefore, the present inventors do not probabilistically determine the seismic strength or the like of the piping network, but consider the entire piping network as a continuum in a predetermined area where it is embedded, and the entire surface of the piping network ( I thought that it would be better to use a method of analyzing the seismic strength of the piping network by the conventional general finite element method using the mesh. .
[0011]
That is, as shown in an example in FIG. 8, the mesh 800 for performing the analysis by the conventional general finite element method as described above is set in the piping 801 of the entire piping network (however, in FIG. For the sake of simplicity, only a small portion of the entire piping network is extracted and shown), and various conditions relating to the mesh 800 and ground displacement are input to an analysis device using a general personal computer. The effectiveness of the technique of analyzing the deformation of the entire piping network by solving the obtained overall stiffness matrix was examined.
[0012]
However, in the deformation analysis method using the mesh 800 according to the conventional general finite element method as described above for the piping 801 of the entire piping network, it looks like a vascular network over a wide area of several tens square kilometers to several hundred square kilometers. Since the mesh 800 is stretched over the entire surface and thickness of the piping network stretched in a very complicated network, and the entire stiffness matrix is created based on the mesh 800, the amount of data is enormous. Therefore, even if a computer capable of high-speed arithmetic processing is used, it takes a lot of time and effort for data input and matrix calculation, which is unrealistic.
[0013]
The present invention has been made in view of such problems, and its purpose is not to obtain the seismic strength of the piping network etc. stochastically, but to be theoretically concrete by structural mechanical or material mechanical techniques. It is another object of the present invention to provide a piping network seismic strength analysis method and a piping network seismic strength analysis apparatus that can be obtained as accurate data and that the analysis method itself is simple and can be executed in a short time.
[0014]
[Means for Solving the Problems]
The pipe network seismic strength analysis method according to the present invention classifies a pipe network provided in a predetermined area into unit elements of a straight line type, a bent pipe type, and a T shape, focusing on the connection form of the pipe, One linear unit element in each unit element is defined as a linear element, and a curved pipe type or T-shaped unit element connected to each end of each unit element is defined as a boundary element. It is assumed that one basic element is composed of a total of three unit elements, and the piping network is discretized for each basic element, and each individual basic element is displaced or distorted by an external force applied by an earthquake. Or, at least one of the stresses is analyzed as seismic strength.
[0015]
In addition, the piping network seismic strength analysis apparatus according to the present invention classifies the piping network provided in a predetermined area into unit elements of a straight line type, a curved pipe type, and a T shape, focusing on the connection form of the pipe. , One linear unit element in each unit element is defined as a linear element, and a curved pipe type or T-shaped unit element connected to each end thereof is used as a boundary element, and the linear element and two boundaries at both ends thereof Assuming that one basic element is composed of a total of three unit elements, the piping network is discretized for each basic element, and each individual basic element is individually subjected to an external force applied by an earthquake. Analyzing means for analyzing at least one of the generated displacement, strain or stress as seismic strength is provided.
[0016]
That is, in the piping network seismic strength analysis method or the piping network seismic strength analysis device according to the present invention, it is considered that one basic element is constituted by a total of three unit elements including a linear element and two boundary elements at both ends thereof. The pipe network is discretized for each basic element (divided and grasped), and for each of the basic elements, at least of the displacement, strain or stress caused by the vibration or external force applied by the earthquake Any one of them is analyzed as seismic strength. Here, “discretization” means that a piping network, which is a continuous body stretched in a network, is regarded as a collection of individual basic elements, and each individual basic element is individually considered. Needless to say, this means that the actual piping network is not physically (mechanically) cut. Further, basic elements adjacent to each other may share one boundary element as a common boundary element.
[0017]
More specifically, the deformation characteristics of the basic element as a boundary element structure at both ends of each linear element are obtained in advance by the finite element method, and at least one of displacement, strain, or stress of the linear element is obtained. You may make it obtain | require a kind from the deformation | transformation characteristic of the boundary element of the both ends of the linear element.
[0018]
That is, regarding the deformation characteristics of the boundary element as a structure, a mesh is stretched over the boundary element, and the deformation characteristics of the boundary element as a structure are obtained in advance by a finite element method using the mesh. It is possible to calculate the deformation of a linear element having the boundary element at both ends.
[0019]
In addition, the boundary elements are classified according to at least one of a classification, a dimension, and a material according to whether the boundary element is a curved pipe type or a T shape, Deformation characteristics for each type are obtained by the finite element method, and deformation characteristic data for each type is stored in a database in advance, and the basic elements to be analyzed are included in the database. The deformation strength data corresponding to the type of boundary element may be selected and used to analyze the seismic strength of the basic element.
[0020]
That is, regarding the deformation characteristics of the boundary element as a structure, a mesh is stretched over the boundary element, the deformation characteristics of the boundary element as a structure are obtained in advance by a finite element method using the mesh, and the information is stored in the database. Therefore, it is possible to use the deformation characteristic data according to the type of boundary element to be analyzed at any time.
[0021]
In addition, at least one type of displacement, strain, or stress of the linear element to be analyzed is established with respect to at least one type of displacement, strain, or stress applied from the boundary elements at both ends to the linear element. It is desirable to obtain the non-linear equation by substituting the deformation characteristic data regarding the boundary element.
[0025]
In the above piping network seismic strength analysis method or piping network seismic strength analysis device, the permissible strength for each unit element of the pipe against the external force or vibration applied by the earthquake is further set, and the permissible strength data, It is also possible to determine the seismic performance of the piping network by comparing the seismic strength data for each basic element obtained by the analysis.
[0026]
Or, when an earthquake occurs, the data on the external force or vibration observed in the earthquake is compared with the seismic strength data for each basic element obtained by the analysis, and the occurrence of damage in the piping network It is also possible to estimate whether or not there is any.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0028]
FIG. 1 shows a schematic configuration of a piping network seismic strength analysis apparatus according to an embodiment of the present invention. In addition, since the piping network seismic strength analysis method according to the embodiment of the present invention is embodied by the operation or action of this piping network seismic strength analysis apparatus, they will be described below together.
[0029]
This piping network seismic strength analysis apparatus includes a boundary element database storage unit (boundary element database storage means) 100 and an earthquake resistance strength analysis unit (analysis means) 200.
[0030]
The boundary element database storage unit 100 uses, for example, a finite element method (FEM) using a detailed mesh stretched on a branch pipe, which is the actual state of the boundary element, for each type of deformation characteristics of the boundary element for each type. The data of the deformation characteristics for each type of boundary element obtained in advance is stored as a database.
[0031]
More specifically, before constructing the boundary element database, first, focusing on the piping connection form, the piping network 300 to be analyzed is divided into a straight type (straight portion) and a curved pipe type (bent bent). Tube unit) and T-shaped (branch tube part branched into T-shape) are classified into three types of unit elements. One linear unit element in each unit element is defined as a linear element, and the straight line A basic element is composed of a total of three unit elements, one of which is a straight line element and two of the boundary elements at both ends, with curved pipe or T-shaped unit elements connected to both ends of the element as boundary elements. Assuming that it is to be performed, the piping network 300 is considered to be discrete for each basic element.
[0032]
FIG. 2 schematically shows an example of a technique for modeling the medium pressure gas conduit by discretization as described above. Actually, it goes without saying that the piping network 300 to be analyzed constitutes a network that is much more complex than that shown in FIG. 2, but in order to simplify the illustration and explanation, in FIG. Only a part of it is extracted and schematically represented by a line drawing.
[0033]
When the discretization method as described above is applied to the piping network 300 having a shape as shown in FIG. 2A, it can be discretized into unit elements as shown in FIG. In the example of the piping network 300 shown in FIG. 2A, a total of 18 unit elements that are discretized (the unit elements that do not constitute basic elements are omitted) are shown in FIG. As shown, when the identification number is attached, the straight type has the second, fourth, eighth, tenth, twelfth, fourteenth, sixteenth, eighteenth, and a valve in the middle of the straight pipe part 6 No., curved pipe type can be classified as No. 7, 11, No. 13, and T-shaped type can be classified as No. 1, No. 3, No. 5, No. 9, No. 15, No. 17. These unit numbers are assigned (unit numbers are respectively indicated by reference numerals 1, 2, 3... 18 in FIG. 2B), and a total of 3 unit elements each linear element and two boundary elements at both ends thereof. A group of elements is defined to constitute a basic element. At this time, the same basic boundary element is shared by adjacent basic elements.
[0034]
Specifically, this will be described with reference to an example of FIG. 2B. An identification number (n = 1, 2.3... 8) is attached to each basic element. If it is written as (number of a-boundary element, number of straight-line element of b, number of boundary element of c), as shown in FIG. For example, the first basic element 21 is {1} = (1, 4, 5), the second basic element 22 is {2} = (5, 14, 15), and the third basic element 23 is {3}. = (15, 16, 9), the fourth basic element 24 is {4} = (9, 8, 7), the fifth basic element 25 is {5} = (7, 6, 3), the sixth The basic element 26 is {6} = (3, 2, 1), the seventh basic element 27 is {7} = (9, 10, 11), and the eighth basic element 28 is {8} = (11, 12). , 13) And Tsu, is for example the basic element 21 No. 1 that are adjacent to each other with the basic element 22 {2} = number 2 and (5,14,15), the boundary element 5 5th are shared.
[0035]
For each of the basic elements as described above, the analysis (seismic strength analysis) of at least one or all of the displacement, strain, or stress caused by the external force applied by the earthquake is performed. Although the strength analysis unit 200 performs, as data used at that time, each boundary element is classified according to the classification according to whether it is a curved pipe type or a T-shaped type, and according to the dimension and the material, For each individual type, the structural mechanical deformation characteristics of the boundary elements are obtained by a finite element method or the like, and the deformation characteristic data for each individual type is stored in the boundary element database storage unit 100. Thereby, the boundary element database storage unit 100 stores the data of the deformation characteristics of the boundary elements for each type in a database.
[0036]
However, it goes without saying that the boundary element database storage unit 100 does not perform the data processing for discretization of the piping network 300 as described above and the analysis based thereon. The operation itself related to the analysis is performed by the seismic strength analysis unit 200 as described later.
[0037]
The deformation characteristic data stored in the boundary element database storage unit 100 is included in the basic element to be analyzed when the seismic strength analysis unit 200 analyzes the seismic strength independently for each basic element. For example, by attaching an identification number or an index to each type of boundary element so that the seismic strength analysis unit 200 can extract and read out the deformation characteristic data corresponding to the type of the boundary element. It is remembered.
[0038]
As the types of boundary elements, first, there is a classification from the viewpoint of the connection structure as the piping, and as described above, this can be classified into a curved pipe type and a T-shaped type. In many cases, the pipe shape corresponding to the curved pipe-type boundary element is bent at right angles to the L-shape, and the pipe shape corresponding to the T-shaped boundary element is composed of three short straight pipes. (Triangular connection pipes) are connected in a T-shape at right angles to each other, but in addition, for example, curved pipe type boundary elements that are not bent at right angles (90 degrees), such as 60 degrees, It goes without saying that T-shaped boundary elements whose tubes are not perpendicular to each other can be analyzed.
[0039]
In addition, as a classification in terms of dimensions, in general, in the gas pipes of medium pressure, low pressure, etc. used for the so-called city gas piping network 300, gas pipes with finer branch lines, etc. Since there are many dimensional standards regarding the thickness, the size of the joint flange, etc., it is possible to classify into several types of dimensions determined by the standard.
[0040]
In terms of classification from the viewpoint of materials, gas conduits, gas pipes and valves are generally standardized for the types of materials, or materials that have been customarily specified from the past may be used. Since there are many, what is necessary is just to classify | categorize according to several types of materials defined by such a standard and designation. For example, there are various types of materials for medium-pressure gas conduits, such as welded steel pipes, ductile cast iron pipes, and gray cast iron pipes, which can be classified according to such materials.
[0041]
The seismic strength analysis unit 200 is independent for each basic element as described above, and at least any one or more of displacement, strain, or stress caused by vibration or external force applied by the earthquake. Analysis is performed to calculate seismic strength data of pipes and valves.
[0042]
More specifically, the seismic strength analysis unit 200 performs modeling for discretizing the piping network 300 into individual basic elements as described above, and analyzes the seismic strength independently for each of the basic elements. I do. An example is shown in FIG. FIG. 4 shows the case where the analysis is performed with respect to the first basic element 21; {1} = (1, 4, 5) described with reference to FIG. The first basic element 21 is formed by connecting a T-shaped first boundary element 1 and a T-shaped fifth boundary element 5 to both ends of a fourth linear element 4. The first basic element 21 is vertically arranged in a letter “E” in FIGS. 2 and 3, but in FIG.
[0043]
As for the deformation characteristics of the first boundary element 1 and the deformation characteristics of the fourth boundary element 5, as described above, the T-shaped branch pipe, other types of bent pipes, etc. The structural mechanical analysis is performed by the finite element method, etc. when external force or vibration is applied, the response data of each type of boundary element is obtained, and the data is converted into a database and stored in the boundary element database Since the data is stored in the unit 100, data relating to the boundary element of the type that respectively matches the size and material of the first boundary element 1 and the size and material of the fourth boundary element 5 is selected from the database. These data can be extracted and used as deformation characteristics for each boundary element 1, 5. More specifically, the deformation characteristic data corresponding to the first boundary element 1 is extracted from the database stored in the boundary element database storage unit 100, and based on the deformation characteristic data. The force F1 applied to the first boundary element 1 can be obtained. Similarly, for the fifth boundary element 5, the force F2 applied to the fifth boundary element 5 can be obtained based on the data of the corresponding deformation characteristics. Alternatively, the displacement amounts u1 and u2 may be obtained instead of the forces F1 and F2.
[0044]
With respect to the fourth linear element 4, the reaction force (-F1) of the force F1 is applied from the first boundary element 1 connected to one end of the straight pipe, and displacement (-u1) is generated. From the fifth boundary element 5 connected to the other end, it can be considered that a reaction force (-F2) of the force F2 is applied and a displacement (-u2) is generated. As given to the straight pipe of the fourth straight element 4, structural mechanical deformation of the straight pipe of the fourth straight element 4 is obtained by using those -F 1, -F 2, -u 1, -u 2. By substituting the data extracted from the above database for the numerical values of F1 and F2 in the nonlinear equation, the deformation of the straight pipe of the fourth straight element 4 can be changed. Convergence calculation is performed to satisfy the conformity condition, and displacement Numerical u1, u2 can be obtained. Based on the displacement values u1 and u2 thus obtained, each unit element constituting the first basic element 21, that is, the first boundary element 1 and the fourth linear element 4 and the fifth boundary element. With respect to 5, it is possible to analyze the aspect of deformation caused by the application of external force or vibration due to an earthquake. Alternatively, the displacements u1 and u2 may be used instead of the forces F1 and F2.
[0045]
In other words, in this analysis method, a state in which an earthquake has occurred in the entire area where the pipe network 300 is provided is as if a “vibration field” having a homogeneous vibration potential is formed in the pipe network 300. As a result, the deformation characteristics of the boundary element assumed when vibration force due to the traveling wave of the earthquake is applied to each boundary element that exists discretely in the `` vibration field '' Based on data such as seismic vibration force (external force), vibration period, amplitude, etc., the data is prepared in a database, and boundary elements having such deformation characteristics are connected to both ends. That is, the deformation data of each straight line element can be obtained based on the deformation characteristic data of the boundary element.
[0046]
Here, for simplification of illustration and explanation, the force F and the displacement u are expressed as one-dimensional values, but in reality, the force F and the displacement u are two-dimensional (force F (x, y), displacement u). (X, y)) or three-dimensional values (force F (x, y, z), displacement u (x, y, z)) (in other words, a vector). Of course, in some cases, it can be handled as a vector in polar coordinate notation. For convenience, the positive and negative values of force and displacement are defined as a positive value for the compression direction and a negative value for the tensile direction with respect to the linear element. Needless to say, the details of the definition and the like can be appropriately changed without departing from the gist of the above calculation method. In addition, it is desirable to use a non-linear equation when obtaining the conformity condition for the deformation of each linear element, but this may use a linear equation when obtaining an approximate solution by simplifying the model. Needless to say.
[0047]
By such a method, not only the first basic element 21 but also the other basic elements 22, 23, 24... Are independently and individually deformed due to the application of external force or vibration caused by the earthquake. It is possible to analyze the aspect. By doing so, it is not necessary to solve the entire stiffness matrix as in the case where the conventional general finite element method is used for the entire piping network 300, so that the calculation method can be made extremely simple. .
[0048]
Next, main operations of the piping network seismic strength analysis apparatus according to the present embodiment will be described. FIG. 5 shows the flow of the main operation. Here, a case where the piping network 300 shown as an example in FIG.
[0049]
First, the seismic strength analysis unit 200 discretizes graphic data as shown in FIG. 2A, which represents the connection relationship of the pipe network 300 to be analyzed, by the above-described method. B) and grasping each unit element of the smallest unit (first boundary element 1, second linear element 2, third boundary element 3, fourth linear element 4...) As shown in FIG. S1).
[0050]
Then, each linear element of the unit elements and the boundary elements connected to both ends thereof constitute one basic element (S2). For example, as described above, the No. 4 linear element 4 and the No. 1 boundary element 1 and No. 5 boundary element 5 at the both ends constitute the No. 1 basic element 21. That is, unit elements in the network 300 are grouped for each basic element.
[0051]
Subsequently, values such as the magnitude of the vibration force given to the piping network 300 due to the earthquake and the vibration period and amplitude are set, and the data is input (S3).
[0052]
Then, based on the set data such as the magnitude of the vibration force related to the earthquake and the deformation characteristic data related to various boundary elements stored in the boundary element database storage unit 100, the external force F applied to each boundary element is calculated. The displacement u of the linear element is obtained by setting u as an unknown, substituting the data into a nonlinear equation representing the fitting condition for the deformation of the linear element having the boundary element at both ends, and solving (calculating) the equation. Is obtained, and the overall deformation and stress for each basic element are analyzed. Alternatively, for each boundary element, the displacement u caused by the earthquake vibration or the like is obtained, the external force F is set as an unknown, and the data is substituted into a nonlinear equation representing the adaptation condition of the linear element having the boundary element at both ends. By calculating the equation, the value of the stress F of the linear element is obtained, and the overall deformation and stress for each basic element are analyzed.
[0053]
More specifically, for example, the boundary elements 1, 3, 5,... For each basic element sequentially from the first basic element 21 to the second basic element 22, the third basic element 23,. The deformation characteristic data corresponding to the type is read out from the database stored in the boundary element database storage unit 100 (S4).
[0054]
Subsequently, for example, with respect to the first basic element 21, data of external force F applied to the boundary element 1 and the boundary element 5 due to the earthquake, respectively, from the read data and data relating to the vibration force of the earthquake, or the like. Each of the displacement u data is obtained (S5).
[0055]
Further, the data of the external force F or the data of the displacement u relating to the boundary elements 1 and 5 are substituted into a nonlinear equation representing the conforming condition of the deformation relating to the linear element 4 having the boundary elements 1 and 5 at both ends (S6). ) If the values of the displacements u1 and u2 are unknown, the values of the displacements u1 and u2 are used, or if the values of the forces F1 and F2 are unknown, the force F1, The value of F2 is obtained by convergence calculation (S7).
[0056]
When the overall deformation and stress analysis for the first basic element 21 is completed in this way (Y in S8), the second basic element 22 is also subjected to the same procedure as described above (Y in S8). → S4 to S7) Analysis of deformation and stress is performed. The analysis of such a procedure is similarly performed on the basic elements 24, 25, 26,... After the third basic element 23, and the number (number n) is finally the last number (this is E). When the analysis of the element (here, the eighth basic element 28) is completed (N in S8), the analysis of the deformation of the piping network 300 due to the earthquake (seismic strength analysis) is completed.
[0057]
As described above, according to the piping network seismic strength analysis apparatus of the present embodiment, the seismic strength of the piping network 300 is not obtained probabilistically, but is analyzed by a structural mechanical method, and is theoretically specified. It can be obtained as accurate and accurate data. Moreover, the analysis method itself has a very practical advantage that it is simple and can be executed in a short time.
[0058]
Here, as an analysis method of seismic strength, in addition to the above, as a method for obtaining an approximate solution in particular, each boundary element is regarded as a rigid node as schematically shown in FIG. The straight line element is regarded as a straight member, and the piping network 300 provided in a predetermined area is regarded as a frame structure in which unit elements are gathered, and vibration and external force due to an earthquake are applied to the frame structure. Assuming the state to be applied, the method of analyzing the displacement or strain or stress generated in the framework structure at that time by solving a simple (small amount of data) stiffness matrix related to the framework structure It is also possible to adopt as a variation of the present embodiment.
[0059]
However, with this method, each boundary element is simplified and regarded as a mere rigid node, and for older valves and the like that tend to be weak, modeling must be simplified and regarded as a mere smooth node. There are many cases where there is no. For this reason, the accuracy of the solution obtained by the analysis method of the first variation is a full-scale considering the deformation characteristics of each boundary element such as the analysis method using the entire stiffness matrix and the analysis method using the discretization described above. It cannot be denied that it tends to be lower than that of a typical analysis method.
[0060]
Therefore, in the analysis method of the first variation, after obtaining a simple stiffness matrix solution related to the frame structure, the force F or displacement u applied to each rigid node, that is, the boundary element, obtained by the solution is obtained. Based on the value and the deformation characteristics data for each boundary element, each boundary element performs an independent (individual) detailed analysis on deformation, so that each boundary element Approximate data such as deformation and stress values caused by vibrations and external forces due to the above may be obtained. Also in this case, the deformation characteristic data for each boundary element is extracted by selecting the data corresponding to the type of boundary element to be analyzed from the database stored in the boundary element database storage unit 100. do it.
[0061]
Alternatively, as schematically illustrated in FIG. 7, each boundary element is regarded as a node having deformation characteristics instead of a rigid node, and the linear element is regarded as a straight member, and the piping network 300 is regarded as a straight member. Adopting the second variation in which the entire structure is regarded as a frame structure made up of unit elements, and the frame structure is analyzed for displacement and stress caused by external forces applied due to an earthquake. It is also possible to do so. In this case, from the beginning, it becomes possible to construct a stiffness matrix for a frame structure that incorporates boundary elements that take into account deformation characteristics as a whole, so that the accuracy of the solution obtained by solving it can be improved. The solution by the analysis method of the first variation can be a highly accurate one reflecting the deformation characteristics of each boundary element from the beginning. In addition, since the deformation characteristic data of each boundary element has already been stored as a database for each type, it is possible to simplify the labor of solving this stiffness matrix, and the time required to obtain the solution is short. Can be.
[0062]
In addition, although illustration was abbreviate | omitted, the allowable intensity | strength for each unit element of the piping network 300 with respect to the external force applied by the vibration applied by the earthquake, the fluidization of the ground which arises by an earthquake, etc. was set, the data of the allowable intensity | strength, and the above-mentioned A seismic performance judging unit having a function of judging seismic performance in the piping network 300 to be analyzed by comparing the seismic strength data for each basic element obtained by an analysis method such as You may make it prepare.
[0063]
For example, as a result of the analysis as described above, the maximum value of the displacement u that occurs in the linear element 4 in the first basic element 21 due to the level 2 earthquake (this is the maximum displacement amount; umax) is umax. Suppose that data that is = 150 [mm] is obtained. At this time, it is assumed that the allowable displacement amount of the straight pipe of the linear element 4 (this is set as Dcr) is set to Dcr = 200 [mm], for example. Alternatively, it is assumed that the allowable displacement amount Dcr = 200 [mm] of the linear element 4 is confirmed by a fracture experiment of a straight pipe of the same type as the linear element 4.
[0064]
Then, the seismic performance determination unit compares the maximum displacement umax = 150 [mm] of the linear element 4 analyzed by the seismic strength analysis unit 200 with the allowable displacement Dcr = 200 [mm] of the linear element 4. , Umax = 150 <Dcr = 200, the linear element 4 is earthquake resistant with a safety factor of 33% (200/150 = 1.33) for level 2 earthquakes (breakage will occur) No).
[0065]
Alternatively, a damage occurrence estimation unit (not shown) that compares the allowable displacement amount Dcr of each unit element in the piping network 300 with the maximum displacement amount umax of the ground observed in the actual earthquake by a substantially similar method. By further providing, it is possible to estimate whether or not the piping network 300 has been damaged.
[0066]
【The invention's effect】
As described above, claims 1 to 8 Piping network seismic strength analysis method or claim 9 Or 16 According to the piping network seismic strength analysis apparatus described in any one of the above, it is assumed that one basic element is constituted by a total of three unit elements including a linear element and two boundary elements at both ends thereof, and the piping network Is discretized for each basic element, and at least one of displacement, strain, or stress caused by vibration or external force applied by an earthquake is analyzed as seismic strength for each basic element. Since it did in this way, when the conventional general finite element method was applied, the analysis of the seismic strength of the piping network which required enormous effort and time can be performed simply and in a short time. In addition, the accuracy of the analysis result obtained thereby can be made the same as when the conventional general finite element method using a detailed mesh is applied to the entire piping network. In addition, since the seismic strength of the piping network is obtained by an analytical method as described above, seismic strength data is obtained as theoretically specific and accurate analytical values, not probabilistic or statistical data. be able to.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a piping network seismic strength analysis apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram schematically showing an example of a method for modeling an intermediate pressure gas conduit by discretization as described above.
FIG. 3 is a diagram schematically showing an example in which an intermediate pressure gas conduit is modeled by discretization as described above, with each basic element individually divided.
FIG. 4 shows a model for discretizing a piping network into individual basic elements by a piping network seismic strength analysis method according to an embodiment of the present invention, and the seismic strength of each individual basic element is independently determined. It is the figure which represented typically an example of the method of analyzing.
FIG. 5 is a diagram showing a flow of main operations of the piping network seismic strength analysis apparatus shown in FIG. 1;
FIG. 6 is a diagram schematically showing a first variation of the piping network seismic strength analysis method.
FIG. 7 is a diagram schematically showing a second variation of the piping network seismic strength analysis method.
FIG. 8 is a diagram illustrating an example in the case where analysis by a finite element method using a conventional general mesh is applied to a piping network.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Boundary element database storage part, 200 ... Seismic strength analysis part, 300 ... Piping network

Claims (16)

The piping network provided in a given area is classified into linear, curved, and T-shaped unit elements, focusing on the piping connection form, and one linear unit element in each unit element. Is a straight line element, and curved tube type or T-shaped unit elements respectively connected to both ends thereof are used as boundary elements, and one basic element is composed of a total of three unit elements of the straight line element and two boundary elements at both ends thereof. The piping network is discretized for each of the basic elements, assuming that it constitutes an element, and at least one of displacement, strain, or stress caused by an external force applied by an earthquake is generated for each of the basic elements. Seismic strength analysis method for piping networks, characterized by analyzing types as seismic strength. Deformation characteristics as a structure of boundary elements at both ends of each linear element in the basic element are obtained in advance by a finite element method, and at least one kind of displacement, strain, or stress of the linear element is calculated as a straight line. 2. The piping network seismic strength analysis method according to claim 1, wherein the method is obtained from deformation characteristics of boundary elements at both ends of the element. The boundary elements are classified according to at least one of a classification, a dimension, and a material classification of whether the boundary element is a curved pipe type or a T shape, and individual types thereof are classified. Deformation characteristics are determined for each element by the finite element method, and the deformation characteristic data for each individual type is stored in a database in advance, and the boundary elements included in the basic element to be analyzed are included in the database. 3. The piping network seismic strength analysis method according to claim 2, wherein the seismic strength of the basic element is analyzed by selecting and using deformation characteristic data corresponding to the type. At least one type of displacement, strain, or stress of the linear element to be analyzed is established with respect to at least one type of displacement, strain, or stress applied to the linear element from boundary elements at both ends. The pipe network seismic strength analysis method according to claim 2, wherein the data is obtained by substituting deformation characteristic data relating to boundary elements at both ends into a nonlinear equation. Set the permissible strength for each unit element of the pipe against external force or vibration applied by an earthquake, and compare the permissible strength data with the seismic strength data for each basic element determined by the analysis The seismic performance of the piping network is determined. The piping network seismic strength analysis method according to any one of claims 1 to 4 . Compare the data on the external force or vibration observed during the earthquake and the data of seismic strength of each basic element obtained by the analysis, and check whether there is any damage in the piping network The pipe network seismic strength analysis method according to any one of claims 1 to 4 , characterized in that: Set the permissible strength for each unit element of the pipe against the external force applied by the fluidization of the ground caused by the occurrence of the earthquake, and the data of the permissible strength and each basic element obtained by the analysis The piping network seismic strength analysis method according to any one of claims 1 to 4 , wherein seismic performance of the piping network is determined by comparing with seismic strength data. The amount of flow observed in the fluidization of the ground caused by the occurrence of the earthquake or the external force data applied to the piping network due to the fluidization of the ground, and the seismic strength for each basic element determined by the analysis The pipe network seismic strength analysis method according to any one of claims 1 to 4 , wherein the pipe network is estimated to determine whether or not damage has occurred in the pipe network. The piping network provided in a given area is classified into linear, curved, and T-shaped unit elements, focusing on the piping connection form, and one linear unit element in each unit element. Is a straight line element, and curved tube type or T-shaped unit elements respectively connected to both ends thereof are used as boundary elements, and one basic element is composed of a total of three unit elements of the straight line element and two boundary elements at both ends thereof. The piping network is discretized for each of the basic elements, assuming that it constitutes an element, and at least one of displacement, strain, and stress caused by an external force applied by an earthquake is individually generated for each of the basic elements. Piping network seismic strength analysis device, characterized in that it has an analysis means for analyzing one type as seismic strength. Deformation characteristics as a structure of a boundary element at both ends of each linear element in the basic element are obtained in advance by a finite element method, and the analysis means is at least one of displacement, strain or stress of the linear element The piping network seismic strength analysis device according to claim 9, wherein the seismic strength analysis device is obtained from deformation characteristics of boundary elements at both ends of the linear element. The boundary elements are classified according to at least one of a classification, a dimension, and a material classification of whether the boundary element is a curved pipe type or a T shape, and individual types thereof are classified. Each of which is further provided with boundary element database storage means for storing the data obtained by obtaining the deformation characteristics by the finite element method and storing the data of the deformation characteristics for each individual type in advance in a database,
The analysis means selects and uses the deformation characteristic data corresponding to the type of boundary element included in the basic element to be analyzed from the data stored in the database, and analyzes the seismic strength of the basic element. The piping network seismic strength analysis apparatus according to claim 10, wherein: The analysis means uses at least one of displacement, strain, or stress of the linear element to be analyzed as at least one of displacement, strain, or stress applied to the linear element from boundary elements at both ends. The piping network seismic strength analysis apparatus according to claim 10 , wherein the data is obtained by substituting the deformation characteristic data regarding the boundary elements at both ends into a nonlinear equation established for one type. Set the permissible strength for each unit element of the pipe against external force or vibration applied by an earthquake, and compare the permissible strength data with the seismic strength data for each basic element determined by the analysis The piping network seismic strength analysis apparatus according to any one of claims 9 to 12 , further comprising seismic performance determining means for determining seismic performance in the piping network. Compare the data on the external force or vibration observed during the earthquake and the data of seismic strength of each basic element obtained by the analysis, and check whether there is any damage in the piping network The piping network seismic strength analysis device according to any one of claims 9 to 12 , further comprising a failure occurrence estimation means for estimating Set the permissible strength for each unit element of the pipe against the external force applied by the fluidization of the ground caused by the occurrence of the earthquake, and the data of the permissible strength and each basic element obtained by the analysis The piping network according to any one of claims 9 to 12 , further comprising seismic performance determination means for comparing seismic strength data with the seismic performance of the piping network. Seismic strength analyzer. The amount of flow observed in the fluidization of the ground caused by the occurrence of the earthquake or the external force data applied to the piping network due to the fluidization of the ground, and the seismic strength of each basic element determined by the analysis The piping according to any one of claims 9 to 12 , further comprising a failure occurrence estimation unit that compares the data with the data and estimates whether or not a failure has occurred in the piping network. Seismic strength analysis device.

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