Method for judging buckling failure of fixed top storage tank

Abstract

The invention discloses a buckling failure judgment method for a fixed-top storage tank, and relates to the technical field of storage tank safety. Comprising the following steps: acquiring buckling modes of the fixed top storage tank under the second-order and multi-order harmonic sedimentation effects; fourier decomposition is carried out on actually measured differential settlement to obtain settlement amplitudes of harmonic waves of different orders; drawing a harmonic settlement amplitude-radial displacement curve of a tank top buckling position, determining a critical settlement amplitude of the tank top, and constructing a tank top buckling failure criterion on the basis to determine a tank top buckling damage factor; drawing a harmonic settlement amplitude-radial displacement curve of the tank wall buckling position, determining a critical settlement amplitude of the tank wall, and constructing a tank wall buckling failure criterion on the basis to determine a tank wall buckling damage factor; and further determining whether the fixed-top storage tank is bent or not and the position of the bent storage tank. According to the method, factors are considered more comprehensively, and the accuracy of the buckling failure judgment result of the fixed top storage tank is improved.

Description

Technical Field

[0001] The invention relates to the technical field of storage tank safety, and in particular to a method for determining buckling failure of a fixed-roof storage tank. Background Art

[0002] A fixed-roof storage tank is a vertical cylindrical storage tank whose top structure is connected to the tank body by welding, and the top is fixed. Under the action of the storage medium and the gravity of the tank, the fixed-roof storage tank will produce various settlement deformations, such as uniform settlement, plane tilt settlement, and uneven settlement. Among them, uneven settlement is the most harmful and will cause damage to the tank body or functional failure. Therefore, establishing the buckling failure and yield failure criteria of fixed-roof storage tanks under uneven settlement is of great significance to ensure the safe operation of fixed-roof storage tanks.

[0003] In the prior art, Marr proposed a control standard for uneven settlement: S = 11L 2 Y / (EH), where S is the maximum allowable value of uneven settlement, L is the arc length between uneven settlement detection points, Y is the yield strength of the tank wall steel, E is the elastic modulus, and H is the tank height. The specific implementation process of determining uneven settlement through this control standard includes: setting multiple uneven settlement detection points on the tank body surface to determine the arc length between the uneven settlement detection points; obtaining the tank height, elastic modulus and yield strength of the tank wall steel through physical measurement, combining the arc length between the uneven settlement detection points with the tank height, elastic modulus and yield strength of the tank wall steel, to obtain the maximum allowable value of uneven settlement, and then formulating the buckling failure judgment criteria for fixed-roof tanks.

[0004] The defects of the above-mentioned prior art are: when determining the arc length between the uneven settlement detection points, only the relevant parameters of the tank body are considered, and the change of the position where the uneven settlement of the tank occurs is not considered, so the buckling failure judgment criterion of the fixed-roof tank is not accurate enough. Summary of the invention

[0005] Based on this, it is necessary to provide a method for determining buckling failure of fixed-roof storage tanks in response to the above technical problems.

[0006] An embodiment of the present invention provides a method for determining buckling failure of a fixed-roof storage tank, comprising:

[0007] Obtain the buckling modes of fixed-roof tanks under 2nd and multi-order harmonic settlement;

[0008] Obtain the measured uneven settlement suffered by the fixed-roof tank, perform Fourier decomposition on the measured uneven settlement, and obtain the settlement amplitude C of different order harmonics n ;

[0009] According to the buckling mode of the fixed-roof tank under the action of the second-order harmonic settlement, the harmonic settlement amplitude-radial displacement curve at the tank top buckling position is drawn; the harmonic settlement amplitude-radial displacement curve at the tank top buckling position is combined with the influence of multi-order harmonic settlement on the radial displacement of the tank top position to obtain the critical settlement amplitude U of the fixed-roof tank top nc-buckle-r ; According to the critical settlement amplitude U of the fixed-roof tank roof nc-buckle-r and the sedimentation amplitude of different order harmonics C n Construct the tank roof buckling failure criterion to determine the tank roof buckling damage factor CDF buckle-r ;

[0010] According to the buckling mode of fixed-roof tank under multi-order harmonic settlement, the harmonic settlement amplitude-radial displacement curve at the buckling position of the tank wall is drawn; the harmonic settlement amplitude-radial displacement curve at the buckling position of the tank wall is combined with the influence of the second-order harmonic settlement on the radial displacement of the tank wall position to obtain the critical settlement amplitude U of the fixed-roof tank wall nc-buckle-w ; According to the critical settlement amplitude U of the fixed roof tank wall nc-buckle-w and the sedimentation amplitude of different order harmonics C n Construct the tank wall buckling failure criterion to determine the tank wall buckling damage factor CDF buckle-w ;

[0011] According to the tank roof buckling damage factor CDF buckle-r and tank wall buckling damage factor CDF buckle-w , determine whether and where buckling occurs in fixed-roof tanks.

[0012] Optionally, the buckling modes of the fixed-roof tank under 2nd and multi-order harmonic settlement are obtained, which includes:

[0013] A numerical model of the tank is established, and the arc length method is used to track the buckling behavior of the fixed-roof tank under harmonic settlement. The buckling behavior includes pre-buckling behavior, buckling critical point, and post-buckling behavior.

[0014] The buckling behaviors of fixed-roof storage tanks under second-order and multi-order harmonic settlement are analyzed respectively, and the buckling modes of the tanks at different orders are obtained.

[0015] Optionally, a harmonic settlement amplitude-radial displacement curve at the tank top buckling position is drawn according to the buckling mode of the fixed-roof storage tank under the action of the second-order harmonic settlement, including:

[0016] The harmonic settlement amplitude of the tank top under the second-order harmonic settlement is used as the horizontal coordinate, and the radial displacement of the tank top is used as the vertical coordinate to draw the harmonic settlement amplitude-radial displacement curve;

[0017] Under the action of the second-order harmonic settlement, when the radial displacement of the tank top reaches the tank top buckling threshold RDRc, the tank top buckles.

[0018] Optionally, according to the critical settlement amplitude U of the fixed-roof tank roof nc-buckle-r and the sedimentation amplitude of different order harmonics C n The tank roof buckling failure criterion is constructed, and its calculation formula is:

[0019]

[0020] Among them, CDF buckle-r is the tank top buckling damage factor, U nc-buckle-r is the critical settlement amplitude of the fixed-roof tank roof, C n is the sedimentation amplitude of harmonics of different orders, n is the harmonic order;

[0021] When CDF buckle-r When CDF is greater than 1, the tank roof buckles. buckle-r When it is less than 1, no buckling occurs on the tank roof.

[0022] Optionally, a harmonic settlement amplitude-radial displacement curve at the tank wall buckling position is drawn according to the buckling mode of the fixed-roof storage tank under the action of multi-order harmonic settlement, including:

[0023] The harmonic settlement amplitude of the tank wall under multi-order harmonic settlement is used as the horizontal coordinate, and the radial displacement of the tank wall is used as the vertical coordinate to draw the harmonic settlement amplitude-radial displacement curve;

[0024] Under the action of multi-order harmonic sedimentation, when the radial displacement of the tank wall reaches the tank wall buckling threshold RDW c The tank wall buckles.

[0025] Optionally, according to the critical settlement amplitude U of the fixed-roof tank wall nc-buckle-w and the sedimentation amplitude of different order harmonics C n The tank wall buckling failure criterion is constructed, and its calculation formula is:

[0026]

[0027] Among them, CDF buckle-w is the tank wall buckling damage factor, U nc-buckle-w is the critical settlement amplitude of the fixed-roof tank wall, C n is the sedimentation amplitude of harmonics of different orders, n is the harmonic order;

[0028] When CDF buckle-w When CDF is greater than 1, the tank wall buckles. buckle-w When it is less than 1, there is no buckling of the tank wall.

[0029] Optionally, determining whether buckling occurs in the fixed roof storage tank and the location where the buckling occurs specifically includes:

[0030] As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Less than 1, tank wall buckling damage factor CDF buckle-w When it is less than 1, no buckling occurs in the fixed-roof tank;

[0031] As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Greater than 1, tank wall buckling damage factor CDF buckle-w When it is less than 1, the tank top buckles but the tank wall does not buckle;

[0032] As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Less than 1, tank wall buckling damage factor CDF buckle-w When it is greater than 1, the tank top does not buckle, but the tank wall buckles.

[0033] Compared with the prior art, the above-mentioned method for determining buckling failure of a fixed-roof storage tank provided by the embodiment of the present invention has the following beneficial effects:

[0034] The present invention draws a harmonic settlement amplitude-radial displacement curve at a tank top buckling position according to the buckling mode of a fixed-roof storage tank under the action of second-order harmonic settlement, determines the critical settlement amplitude of the tank top of the fixed-roof storage tank, and builds a tank top buckling failure criterion on this basis to determine the tank top buckling damage factor; draws a harmonic settlement amplitude-radial displacement curve at a tank wall buckling position according to the buckling mode of the fixed-roof storage tank under the action of multi-order harmonic settlement, determines the critical settlement amplitude of the tank wall of the fixed-roof storage tank, and builds a tank wall buckling failure criterion on this basis to determine the tank wall buckling damage factor; and determines whether buckling occurs in the fixed-roof storage tank and the position where buckling occurs according to the tank top buckling damage factor and the tank wall buckling damage factor.

[0035] Compared with the prior art, the above process considers the influence of multi-order harmonic settlement on the radial displacement of the tank top position in the process of constructing the tank top buckling failure criterion under the action of second-order harmonic settlement; considers the influence of second-order harmonic settlement on the radial displacement of the tank wall position in the process of constructing the tank wall buckling failure criterion under the action of multi-order harmonic settlement; considers the influence of second-order and multi-order harmonic settlement on the radial displacement on both the tank top and the tank wall of the fixed-roof storage tank, and considers the factors more comprehensively, thereby improving the accuracy of the buckling failure judgment result of the fixed-roof storage tank, and the method is simple and convenient for engineering application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic flow chart of a method for determining buckling failure of a fixed-roof storage tank provided in an embodiment;

[0037] Figure 2is a buckling modal diagram of a fixed-roof storage tank under harmonic settlement in a buckling failure determination method for a fixed-roof storage tank provided in an embodiment, Figure 2 (a) is the buckling mode under the second-order harmonic settlement. Figure 2 (b) is the buckling mode under the third-order harmonic settlement. Figure 2 (c) in the figure is the buckling mode under the action of the fourth-order harmonic settlement. Figure 2 (d) in the figure is the buckling mode under the fifth-order harmonic settlement. Figure 2 (e) in the figure is the buckling mode under the action of the sixth-order harmonic settlement. Figure 2 (f) in the figure is the buckling mode under the 7th harmonic settlement. Figure 2 (g) in the figure is the buckling mode under the 8th harmonic settlement;

[0038] Figure 3 A settlement-displacement curve diagram of a tank wall buckling position of a method for determining buckling failure of a fixed-roof storage tank provided in one embodiment;

[0039] Figure 4 A method for determining buckling failure of a fixed roof storage tank provided in an embodiment is shown in FIG. 2c-buckle-w Schematic diagram of the calculation process;

[0040] Figure 5 A tank top buckling position settlement-displacement curve diagram of a method for determining buckling failure of a fixed-roof storage tank provided in one embodiment;

[0041] Figure 6 A method for determining buckling failure of a fixed roof storage tank provided in an embodiment is shown in FIG. 3c-buckle-r Schematic diagram of the calculation process;

[0042] Figure 7 is a load proportional factor-displacement curve diagram of a method for determining buckling failure of a fixed-roof storage tank provided in an embodiment, Figure 7 (a) is the buckling mode, Figure 7 (b) in the figure is the load proportional factor-displacement curve. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] In one embodiment, a method for determining buckling failure of a fixed roof tank is provided, such as Figure 1 As shown, the method includes:

[0045] Step 1 Obtain the buckling modes of the fixed-roof tank under the second-order and multi-order harmonic settlement.

[0046] Step 2: Obtain the measured uneven settlement suffered by the fixed-roof tank, perform Fourier decomposition on the measured uneven settlement, and obtain the settlement amplitude C of different order harmonics. n .

[0047] Step 3: Draw the harmonic settlement amplitude-radial displacement curve of the tank top buckling position according to the buckling mode of the fixed-roof tank under the action of the second-order harmonic settlement; the harmonic settlement amplitude-radial displacement curve of the tank top buckling position is combined with the influence of multi-order harmonic settlement on the radial displacement of the tank top position to obtain the critical settlement amplitude U of the fixed-roof tank top. nc-buckle-r ; According to the critical settlement amplitude U of the fixed-roof tank roof nc-buckle-r and the sedimentation amplitude of different order harmonics C n Construct the tank roof buckling failure criterion to determine the tank roof buckling damage factor CDF buckle-r .

[0048] The harmonic settlement amplitude of the tank top under the second-order harmonic settlement is used as the horizontal coordinate, and the radial displacement of the tank top is used as the vertical coordinate to draw the harmonic settlement amplitude-radial displacement curve. Under the action of the second-order harmonic settlement, when the radial displacement of the tank top reaches the tank top buckling threshold RDRc, the tank top buckles.

[0049] Step 4: Draw the harmonic settlement amplitude-radial displacement curve at the buckling position of the tank wall according to the buckling mode of the fixed-roof tank under the action of multi-order harmonic settlement; the harmonic settlement amplitude-radial displacement curve at the buckling position of the tank wall is combined with the influence of the second-order harmonic settlement on the radial displacement of the tank wall position to obtain the critical settlement amplitude U of the fixed-roof tank wall. nc-buckle-w ; According to the critical settlement amplitude U of the fixed roof tank wall nc-buckle-w and the sedimentation amplitude of different order harmonics C n Construct the tank wall buckling failure criterion to determine the tank wall buckling damage factor CDF buckle-w .

[0050] Among them, the harmonic settlement amplitude of the tank wall under multi-order harmonic settlement is used as the horizontal coordinate, and the radial displacement of the tank wall is used as the vertical coordinate to draw the harmonic settlement amplitude-radial displacement curve. Under the action of multi-order harmonic settlement, when the radial displacement of the tank wall reaches the tank wall buckling threshold RDW c The tank wall buckles.

[0051] Step 5: Based on the tank top buckling damage factor CDF buckle-r and tank wall buckling damage factor CDF buckle-w , determine whether and where buckling occurs in fixed-roof tanks.

[0052] As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Less than 1, tank wall buckling damage factor CDF buckle-w When it is less than 1, no buckling occurs in the fixed roof tank.

[0053] As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Greater than 1, tank wall buckling damage factor CDF buckle-w When it is less than 1, the tank top buckles but the tank wall does not buckle.

[0054] As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Less than 1, tank wall buckling damage factor CDF buckle-w When it is greater than 1, the tank top does not buckle, but the tank wall buckles.

[0055] A specific embodiment of the present invention is provided:

[0056] (1) A numerical model of the tank is established, and the arc length method is used to track the pre-buckling behavior, critical buckling point, and post-buckling behavior of the tank under harmonic settlement.

[0057] (2) Buckling analysis, such as Figure 2 As shown, for 10000m 3 The buckling modes of fixed roof tanks under 2nd to 8th order harmonic settlement are analyzed to determine the buckling modes of tanks at different orders.

[0058] Figure 2 (a) is the buckling mode under the second-order harmonic settlement. Figure 2 (b) is the buckling mode under the third-order harmonic settlement. Figure 2 (c) in the figure is the buckling mode under the action of the fourth-order harmonic settlement. Figure 2 (d) in the figure is the buckling mode under the fifth-order harmonic settlement. Figure 2 (e) in the figure is the buckling mode under the action of the sixth-order harmonic settlement. Figure 2 (f) in the figure is the buckling mode under the 7th harmonic settlement. Figure 2 (g) in the figure is the buckling mode under the action of 8th-order harmonic settlement.

[0059] Under the action of 3rd to 8th order harmonic settlement, the buckling position of the tank is located at the bottom of the tank wall; under the action of 2nd order harmonic settlement, the buckling position of the tank is located at the top of the tank. Because the buckling position of the tank is different under the action of harmonic settlement of different orders, it is necessary to establish corresponding buckling failure criteria for different buckling positions.

[0060] (3) Establishment of tank wall buckling criteria

[0061] The harmonic settlement amplitude-radial displacement curve at the tank wall buckling position is as follows: Figure 3 As shown in the figure, under the action of harmonic settlement, the harmonic settlement amplitude-radial displacement curve initially changes linearly. After reaching the critical harmonic settlement amplitude, the radial displacement increases rapidly. Under the action of multi-order (n=3, 4, 5, 6, 7, 8) harmonic settlement, when the radial displacement of the tank wall reaches the tank wall buckling threshold RDW, c When , the tank wall buckles. Since the uneven settlement can be expressed as the superposition value of harmonic settlement of different orders through the Fourier basis, the tank wall buckling failure criterion under the action of uneven settlement can be expressed as:

[0062]

[0063] Among them, CDF buckle-w is the tank wall buckling damage factor, U nc-buckle-w is the critical settlement amplitude of the fixed-roof tank wall, C n is the sedimentation amplitude of different order harmonics, and n is the harmonic order. buckle-w When CDF is greater than 1, the tank wall buckles. buckle-w When it is less than 1, there is no buckling of the tank wall.

[0064] Through the tank buckling modal analysis, it can be found that although the buckling position of the tank occurs at the tank top under the second-order harmonic settlement, it is necessary to consider the influence of the radial displacement of the tank wall position caused by the second-order harmonic settlement on the tank wall buckling. 2c-buckle-w It cannot be directly obtained by numerical techniques, but can be obtained by Figure 4 The method provided determines U 2c-buckle-w First, you can Figure 4 Determine the tank wall buckling threshold RDW c ; Then, extend the linear part of the harmonic settlement amplitude-radial displacement curve; Finally, determine U 2c-buckle-w Value, U 2c-buckle-w Values ​​are only used to calculate CDF buckle-w , and has no actual physical meaning. Figure 4 The unloading of the nonlinear part is caused by the unloading of the tank wall after the tank roof buckles. Table 1 lists the U nc-buckle-w The value of .

[0065] Table 1U nc-buckle-w value

[0066] <![CDATA[U 2c-buckle-w ]]> <![CDATA[U 3c-buckle-w ]]> <![CDATA[U 4c-buckle-w ]]> <![CDATA[U 5c-buckle-w ]]> <![CDATA[U 6c-buckle-w ]]> <![CDATA[U 7c-buckle-w ]]> <![CDATA[U 8c-buckle-w ]]> 12.5mm 3.9mm 2.9mm 2.1mm 1.7mm 1.4mm 1.1mm

[0067] (4) Tank roof buckling criterion

[0068] The harmonic settlement amplitude-radial displacement curve of a fixed-roof tank under the action of second-order harmonic settlement is as follows: Figure 5 As shown in the figure, it is assumed that when the radial displacement of the tank top reaches the tank top buckling threshold RDRc, the tank top buckles. Similarly, the influence of the radial displacement of the tank top position caused by n=3, 4, 5, 6, 7, 8 harmonic settlement on the tank wall buckling is considered to establish the buckling criterion of the tank top under the action of uneven settlement. Determine U 3c-buckle-r The process and U 2c-buckle-w Same, such as Figure 6 As shown, U 4c-buckle-r , U 5c-buckle-r with U 6c-buckle-r The determination process will not be repeated. Under the action of n=7,8 order harmonic settlement, the radial direction of the tank top is extremely small and can be ignored. The buckling failure criterion of the tank top under the action of uneven settlement can be expressed as:

[0069]

[0070] Among them, CDF buckle-r is the tank top buckling damage factor, U nc-buckle-r is the critical settlement amplitude of the fixed-roof tank roof, C n is the sedimentation amplitude of different order harmonics, and n is the harmonic order. buckle-r When CDF is greater than 1, the tank roof buckles. buckle-r When it is less than 1, the tank roof does not buckle. Table 2 lists the U nc-buckle-r The value of .

[0071] Table 2U nc-buckle-r value

[0072] <![CDATA[U 2c-buckle-r ]]> <![CDATA[U 3c-buckle-r ]]> <![CDATA[U 4c-buckle-r ]]> <![CDATA[U 5c-buckle-r ]]> <![CDATA[U 6c-buckle-r ]]> <![CDATA[U 7c-buckle-r ]]> <![CDATA[U 8c-buckle-r ]]> 5.5mm 7.7mm 19.4mm 25.8mm 60.6mm 0 0

[0073] For example, Figure 7 As shown, Figure 7 (a) is the buckling mode, Figure 7 (b) in the figure is the load proportional factor-displacement curve. The proposed method was used to calculate whether the tank would buckle under the measured uneven settlement, and the calculation results were verified using finite element calculation. The settlement detection points of the selected tank settlement cases are 12, and the Fourier basis is used to decompose them to obtain the harmonic settlement amplitude. See Table 3, calculate CDF respectively. buckle-w , CDF buckle-r value.

[0074] Table 3 Harmonic Settlement Amplitude

[0075] <![CDATA[C0]]> <![CDATA[C1]]> <![CDATA[C2]]> <![CDATA[C3]]> <![CDATA[C4]]> <![CDATA[C5]]> <![CDATA[C6]]> Case 1 11.7 12.1 7.7 3.4 2.1 1.9 2.3

[0076] For Case 1, CDF buckle-w The value of is 4.47, CDF buckle-r The value of is 2.06, CDFbuckle-w Greater than CDF buckle-r , indicating that the tank wall buckles first. Further analysis shows that when the load proportional factor is 0.22 (= 1 / 4.47), the tank wall begins to buckle. The finite element calculation results show that when the load proportional factor is 0.3, the tank top begins to buckle.

[0077] The load proportional factor is a variable value. buckle-r and tank wall buckling damage factor CDF buckle-w When both are less than 1, the load proportional factor can be used to amplify them simultaneously and observe the order of the two factors being greater than 1. buckle-r If the tank wall buckling damage factor CDF buckle-w If it is greater than 1, the tank wall will buckle.

[0078] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for determining buckling failure of a fixed roof storage tank, characterized in that: include: Obtain the buckling modes of fixed-roof tanks under 2nd and multi-order harmonic settlement; Obtain the measured uneven settlement suffered by the fixed-roof tank, perform Fourier decomposition on the measured uneven settlement, and obtain the settlement amplitude C of different order harmonics n ; According to the buckling mode of the fixed-roof tank under the action of the second-order harmonic settlement, the harmonic settlement amplitude-radial displacement curve at the tank top buckling position is drawn; the harmonic settlement amplitude-radial displacement curve at the tank top buckling position is combined with the influence of multi-order harmonic settlement on the radial displacement of the tank top position to obtain the critical settlement amplitude U of the fixed-roof tank top nc-buckle-r ; According to the critical settlement amplitude U of the fixed-roof tank roof nc-buckle-r and the sedimentation amplitude of different order harmonics C n Construct the tank roof buckling failure criterion to determine the tank roof buckling damage factor CDF buckle-r ; According to the buckling mode of fixed-roof tank under multi-order harmonic settlement, the harmonic settlement amplitude-radial displacement curve at the buckling position of the tank wall is drawn; the harmonic settlement amplitude-radial displacement curve at the buckling position of the tank wall is combined with the influence of the second-order harmonic settlement on the radial displacement of the tank wall position to obtain the critical settlement amplitude U of the fixed-roof tank wall nc-buckle-w ; According to the critical settlement amplitude U of the fixed roof tank wall nc-buckle-w and the sedimentation amplitude of different order harmonics C n Construct the tank wall buckling failure criterion to determine the tank wall buckling damage factor CDF buckle-w ; According to the tank roof buckling damage factor CDF buckle-r and tank wall buckling damage factor CDF buckle-w , determine whether and where buckling occurs in fixed-roof tanks.

2. A method for determining buckling failure of a fixed-roof storage tank according to claim 1, characterized in that: The method of obtaining the buckling modes of the fixed-roof storage tank under the second-order and multi-order harmonic settlement includes: A numerical model of the tank is established, and the arc length method is used to track the buckling behavior of the fixed-roof tank under harmonic settlement, wherein the buckling behavior includes pre-buckling behavior, buckling critical point and post-buckling behavior; The buckling behaviors of fixed-roof storage tanks under second-order and multi-order harmonic settlement are analyzed respectively, and the buckling modes of the tanks at different orders are obtained.

3. A method for determining buckling failure of a fixed-roof storage tank according to claim 1, characterized in that: The method of drawing a harmonic settlement amplitude-radial displacement curve at the tank top buckling position according to the buckling mode of the fixed-roof storage tank under the action of the second-order harmonic settlement includes: The harmonic settlement amplitude of the tank top under the second-order harmonic settlement is used as the horizontal coordinate, and the radial displacement of the tank top is used as the vertical coordinate to draw the harmonic settlement amplitude-radial displacement curve; Under the action of the second-order harmonic settlement, when the radial displacement of the tank top reaches the tank top buckling threshold RDRc, the tank top buckles.

4. A method for determining buckling failure of a fixed roof storage tank according to claim 1, characterized in that: The critical settlement amplitude U of the fixed-roof tank roof is nc-buckle-r and the sedimentation amplitude of different order harmonics C n The tank roof buckling failure criterion is constructed, and its calculation formula is: Among them, CDF buckle-r is the tank top buckling damage factor, U nc-buckle-r is the critical settlement amplitude of the fixed-roof tank roof, C n is the sedimentation amplitude of harmonics of different orders, n is the harmonic order; When CDF buckle-r When CDF is greater than 1, the tank roof buckles. buckle-r When it is less than 1, no buckling occurs on the tank roof.

5. A method for determining buckling failure of a fixed roof storage tank according to claim 1, characterized in that: The method of drawing a harmonic settlement amplitude-radial displacement curve at the tank wall buckling position according to the buckling mode of the fixed-roof storage tank under the action of multi-order harmonic settlement includes: The harmonic settlement amplitude of the tank wall under multi-order harmonic settlement is used as the horizontal coordinate, and the radial displacement of the tank wall is used as the vertical coordinate to draw the harmonic settlement amplitude-radial displacement curve; Under the action of multi-order harmonic sedimentation, when the radial displacement of the tank wall reaches the tank wall buckling threshold RDW c The tank wall buckles.

6. A method for determining buckling failure of a fixed roof storage tank according to claim 1, characterized in that: The critical settlement amplitude U of the fixed roof tank wall nc-buckle-w and the sedimentation amplitude of different order harmonics C n The tank wall buckling failure criterion is constructed, and its calculation formula is: Among them, CDF buckle-w is the tank wall buckling damage factor, U nc-buckle-w is the critical settlement amplitude of the fixed-roof tank wall, C n is the sedimentation amplitude of harmonics of different orders, n is the harmonic order; When CDF buckle-w When CDF is greater than 1, the tank wall buckles. buckle-w When it is less than 1, there is no buckling of the tank wall.

7. A method for determining buckling failure of a fixed roof storage tank according to claim 1, characterized in that: The step of determining whether buckling occurs in the fixed roof storage tank and the location where buckling occurs specifically includes: As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Less than 1, tank wall buckling damage factor CDF buckle-w When it is less than 1, no buckling occurs in the fixed-roof tank; As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Greater than 1, tank wall buckling damage factor CDF buckle-w When it is less than 1, the tank top buckles but the tank wall does not buckle; As the measured differential settlement of fixed-roof tanks increases, the tank roof buckling damage factor CDF buckle-r Less than 1, tank wall buckling damage factor CDF buckle-w When it is greater than 1, the tank top does not buckle, but the tank wall buckles.

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