Calculation method and early warning system for out-of-plane wind stability of aluminum alloy portal frames

Abstract

The present invention relates to a tent construction technology with an aluminum alloy structure, and specifically to a method for calculating the out-of-plane wind resistance stability of an aluminum alloy portal frame. The present invention aims to solve the problem of checking the stable bearing capacity of the aluminum alloy portal frame under out-of-plane wind loads. By simplifying the out-of-plane wind load to a linear load acting on the aluminum alloy portal frame beams and columns, the out-of-plane anti-lateral displacement structure of the aluminum alloy portal frame is simplified to a plane truss, and finally the wind resistance stability is checked by controlling the displacement limit of the simplified plane truss under the action of the linear load. The present invention can complete the out-of-plane wind resistance stability check of the aluminum alloy portal frame through rapid calculation, thereby ensuring the stability of the overall structure under complex wind loads.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a tent construction technology with an aluminum alloy structure, and specifically to a calculation method for the out-of-plane wind resistance stability of an aluminum alloy portal frame and an early warning system thereof. Background Art

[0002] In engineering technology, "portal frame" is a traditional structural system. The upper main frame of this type of structure includes frame diagonal beams, frame columns, and supports. Further, on this basis, "aluminum alloy portal frame" specifically refers to a portal frame structure composed of aluminum alloy components. The main force of this structure comes from plane loads, especially from the action of wind. When subjected to large wind loads, the aluminum alloy portal frame structure will deform significantly, thus affecting its normal use function and even causing collapse and damage. Among them, the out-of-plane direction (abbreviated as "out-of-plane", such as Figure 1 The direction marked by the arrow in the figure is the weak direction of the aluminum alloy portal frame in terms of wind resistance. Therefore, it is often necessary to set diagonal braces (or scissor braces) at the aluminum alloy portal frame to strengthen the rigidity of the aluminum alloy portal frame, so that it has reliable bending and lateral rigidity, thereby avoiding being blown down by strong winds.

[0003] In the above reinforcement process of the aluminum alloy portal frame, due to the lack of verification assistance of theoretical calculation methods, the problem of excessive or insufficient diagonal bracing of the aluminum alloy portal frame often occurs. Especially when the diagonal bracing is insufficient, the entire aluminum alloy portal frame still has the problem of collapse due to insufficient rigidity due to external factors; thus, there are safety hazards in the current use of the aluminum alloy portal frame.

[0004] At present, the verification method for the out-of-plane wind stability of portal frames is mainly concentrated in the field of steel structures. The portal frames in the form of steel structures mainly ensure the stability of the structure under wind loads by controlling the lateral displacement of the frame. The elastic modulus of aluminum alloy is about 1 / 3 of that of steel, so the deformation mechanism of aluminum alloy structure is quite different from that of steel structure. Therefore, the existing calculation method and limit value of wind stability displacement of steel portal frames cannot be applied to the verification of aluminum alloy portal frame structures. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects and propose a calculation method and a monitoring system for the out-of-plane wind resistance stability of an aluminum alloy portal frame, thereby improving the safety of the aluminum alloy portal frame during use.

[0006] In order to achieve the above object, the present invention is achieved in the following ways:

[0007] A method for calculating the out-of-plane wind resistance stability of an aluminum alloy portal frame comprises the following steps:

[0008] Step 1: Calculate the equivalent linear load of the aluminum alloy portal frame according to the out-of-plane windward and leeward areas of the aluminum alloy portal frame and the wind load:

[0009]

[0010] Where: q is the equivalent linear load generated by the out-of-plane wind load, w k is the basic wind pressure standard value, A w is the area of ​​the gable wall, μ z is the wind pressure height coefficient, N is the number of diagonal braces spans outside the aluminum alloy portal frame, and L is the sum of the lengths of beams and columns of a single span aluminum alloy portal frame;

[0011] Step 2: Based on the wind load, geometric dimensions, and aluminum alloy properties of the aluminum alloy portal frame, the existing in-plane stiffness calculation formula for the cross grid is used as a reference, and the out-of-plane wind resistance characteristics of the aluminum alloy portal frame structure are considered. The following formula is established to calculate the mid-span displacement of the aluminum alloy portal frame under the equivalent linear load:

[0012]

[0013] Where: E x and A x are the elastic model and cross-sectional area of ​​the secondary component, E c and A c are the elastic modulus and cross-sectional area of ​​the diagonal brace, α is the angle between the diagonal brace and the aluminum alloy portal frame beam and column, q is the equivalent wind load of the out-of-plane load, n is the number of half-span grids, x is the length of the grid along the span direction, and y is the length of the grid perpendicular to the span direction;

[0014] Step 3: Use ABAQUS to establish a large number of out-of-plane analysis models of aluminum alloy portal frames with different spans and arch angles, apply a linear load to the model until the structural stress reaches the design value, and then record the out-of-plane wind displacement limit of the aluminum alloy portal frame at this time; based on the large number of out-of-plane wind displacement limits obtained in the above process, fit the out-of-plane wind instability displacement limit calculation formula of the aluminum alloy portal frame, that is, the out-of-plane wind displacement limit of the aluminum alloy portal frame:

[0015]

[0016] Where: [V] is the mid-span out-of-plane displacement limit, h is the height of the aluminum alloy portal frame column, l is the span of the aluminum alloy portal frame, and θ is the angle between the aluminum alloy portal frame beam and column;

[0017] Step 4: Compare the mid-span displacement data of the aluminum alloy portal frame calculated in step 2 with the displacement limit obtained in step 3. If the former is greater than the latter, the structure is wind-resistant and unstable; otherwise, it is not unstable.

[0018] In the above-mentioned calculation method for the out-of-plane wind stability of the aluminum alloy portal frame, the equivalent action form of the out-of-plane wind load of the aluminum alloy portal frame is a line load; the reason is that the method of simplifying the out-of-plane wind load to a line load is relatively mature, which can not only ensure the safety of the structural calculation, but also is simple and easy to use.

[0019] On the basis of the above, the present invention further proposes an out-of-plane wind resistance warning system for an aluminum alloy portal frame with an automatic monitoring function. The warning system relies on the calculation formula proposed by the present invention, and realizes the automatic calculation and safety monitoring function of the wind resistance of the aluminum alloy portal frame through industrial control software and equipment.

[0020] Specifically, the aluminum alloy portal frame out-of-plane wind resistance early warning system proposed in the present invention includes an aluminum alloy portal frame constructed after calculation by the above-mentioned aluminum alloy portal frame out-of-plane wind resistance stability calculation method, and a laser displacement sensor arranged at the top mid-span (i.e., the ridge position) of the aluminum alloy portal frame with a diagonal brace. The laser displacement sensor is used to observe and collect the mid-span out-of-plane displacement of the aluminum alloy portal frame and send the actual mid-span out-of-plane displacement of the aluminum alloy portal frame to the outside world for comparison with the mid-span out-of-plane displacement limit [V] calculated by the calculation method.

[0021] The above-mentioned early warning system also includes a wireless or wired network transmission module and an operation terminal. The network transmission module sends the mid-span out-of-plane displacement of the aluminum alloy portal frame collected by the laser displacement sensor to the operation terminal for timely observation. The monitoring frequency of the laser displacement sensor under normal weather conditions is once a day, and the monitoring frequency under windy weather conditions is once an hour.

[0022] The above-mentioned early warning system also includes an operation terminal, which compares the actual mid-span out-of-plane displacement of the aluminum alloy portal frame received with the mid-span out-of-plane displacement limit [V] calculated by the calculation formula obtained by the above-mentioned aluminum alloy portal frame out-of-plane wind stability calculation method. When the ratio reaches 0.6, a preliminary warning is issued, when the ratio reaches 0.8, a formal warning is issued, and when the ratio reaches 0.95, a serious warning is issued.

[0023] In summary, the calculation method for the out-of-plane wind stability of the above-mentioned aluminum alloy portal frame proposed in the present invention is different from the verification method of the existing steel structure portal frame. Taking into account the characteristics of the elastic modulus of aluminum alloy material, the calculation method proposed in the present invention simplifies the complex wind stability problem of the aluminum alloy portal frame into the calculation of truss deformation, thereby ensuring that the calculation formula can be used quickly and accurately in actual engineering.

[0024] Furthermore, the calculation method for the out-of-plane wind resistance stability of the aluminum alloy portal frame proposed in the present invention involves calculation formulas that have been rigorously deduced and fitted with sufficient data, fully guaranteeing the stability of the calculation method. In this way, even if the aluminum alloy portal frame is increasingly widely used in temporary buildings, the calculation method proposed in the present invention can also provide reliable theoretical support for the promotion and application of such structures, thereby improving the safety of temporary buildings made of aluminum alloy.

[0025] Therefore, the out-of-plane wind stability calculation method of the aluminum alloy portal frame proposed in the present invention can be widely applied to aluminum alloy buildings composed of portal frame beams, columns, secondary components and diagonal braces made of aluminum alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the following drawings in the embodiments are introduced. The following drawings only show some embodiments of the present invention and therefore should not be considered as limiting the scope of the present invention:

[0027] Figure 1 It is a structural schematic diagram of the aluminum alloy portal frame in the present invention.

[0028] Figure 2 It is a schematic diagram of the structure of the diagonal bracing part of the wind-resistant belt in the present invention.

[0029] Figure 3 This is a simplified truss calculation diagram in the present invention.

[0030] Figure 4 Schematic diagram of the calculation model of the embodiment of the present invention.

[0031] Figure 5 Schematic diagram of load calculation model in the embodiment of the present invention.

[0032] Figure 6 Schematic diagram of displacement calculation results of an embodiment of the present invention.

[0033] Figure 7 It is a schematic diagram of the stress calculation results of an embodiment of the present invention.

[0034] In the figure: 1. Aluminum alloy portal frame column; 2. Aluminum alloy portal frame beam; 3. Secondary components; 4. Diagonal brace; 5. Other components. DETAILED DESCRIPTION

[0035] The present invention is further described below by means of specific examples.

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] See also Figure 1 and 2 As shown, a method for calculating the out-of-plane wind stability of an aluminum alloy portal frame can be used to check the out-of-plane wind stability bearing capacity of the main frame of the aluminum alloy portal frame. Through the verification of this calculation formula, the structure of the aluminum alloy portal frame can be simplified, while reducing its overall weight and structural complexity, its overall wind resistance and self-stability can be ensured to the greatest extent.

[0038] Further, see also Figure 1 and 2 As shown, the out-of-plane wind stability calculation method of the aluminum alloy portal frame described in this embodiment is also applicable to the frame structure with zippers for diagonal supports.

[0039] See also Figure 3 As shown, a calculation method for the out-of-plane wind stability of an aluminum alloy portal frame is provided. The displacement limit of the simplified plane truss under the action of the line load is used to realize the verification of wind stability. The specific steps are as follows:

[0040] Step 1: Calculate the equivalent wind load (line load) of the aluminum alloy portal frame according to the area of ​​the windward and leeward surfaces outside the aluminum alloy portal frame and the wind load:

[0041]

[0042] Where: q is the equivalent wind load of the out-of-plane load, w k is the basic wind pressure standard value, A w is the area of ​​the gable wall, μ z is the wind pressure height coefficient, N is the number of diagonal braces spans outside the aluminum alloy portal frame, and L is the sum of the lengths of beams and columns of a single span aluminum alloy portal frame;

[0043] Step 2: Calculate the mid-span displacement of the aluminum alloy portal frame under the equivalent wind load (line load) based on the wind load, geometric dimensions, and aluminum alloy properties of the aluminum alloy portal frame:

[0044]

[0045] Where: E x and A x are the elastic model and cross-sectional area of ​​the secondary component, E c and Ac are the elastic modulus and cross-sectional area of ​​the diagonal brace, α is the angle between the diagonal brace and the aluminum alloy portal frame beam-column (beam and column), q is the equivalent wind load of the out-of-plane load, n is the number of half-span grids, x is the length of the grid along the span direction, y is the length of the grid perpendicular to the span direction, i is the i-th grid (e.g. Figure 3 Grid in );

[0046] Step 3: Calculate the out-of-plane instability displacement limit according to the geometric dimensions of the aluminum alloy portal frame:

[0047]

[0048] Where: [V] is the mid-span out-of-plane displacement limit, h is the height of the aluminum alloy portal frame column, l is the span of the aluminum alloy portal frame, and θ is the angle between the aluminum alloy portal frame beam and column;

[0049] Step 4: Compare the mid-span displacement with the displacement limit. If the former is greater than the latter, the structure is wind-resistant and unstable; otherwise, it is not unstable.

[0050] Example 2, Example 2 discloses an early warning system of an aluminum alloy portal frame constructed after verification based on the calculation method shown in Example 1. (In actual application, in order to ensure personal and property safety, the wind resistance stability of the aluminum alloy portal frame in use needs to be observed in real time), specifically as follows:

[0051] After the aluminum alloy portal frame is built, during normal use, a laser displacement sensor is used to measure the out-of-plane displacement of the aluminum alloy portal frame at the mid-span of the aluminum alloy portal frame. Specifically, the actual displacement is observed and collected by a displacement sensor arranged at the top mid-span position (or ridge position) of the aluminum alloy portal frame with diagonal braces.

[0052] The actual displacement data collected by the above displacement sensor is transmitted to the operation terminal through the network transmission module for comparison. The monitoring frequency of the displacement sensor under normal weather conditions is once a day, and the monitoring frequency under windy weather conditions is once an hour.

[0053] After receiving the actual mid-span out-of-plane displacement data of the aluminum alloy portal frame, the operating terminal compares it with the calculated mid-span out-of-plane displacement limit [V]. When the ratio reaches 0.6, a preliminary warning is issued; when the ratio reaches 0.8, a formal warning is issued; and when the ratio reaches 0.95, a serious warning is issued.

[0054] In order to verify the effectiveness of the out-of-plane wind stability calculation method and early warning system of the aluminum alloy portal frame described in the above-mentioned Example 1 and Example 2, the main component and secondary component node design of a certain existing aluminum alloy portal frame structure was carried out, and an overall analysis model was established based on the design results.

[0055] like Figure 4 As shown, the span of the aluminum alloy portal frame is 40m and the column height is 8m; the cross-sectional dimensions of the main component are H300×125×8×10, and the cross-sectional dimensions of the secondary beam are H120×100×6×8.

[0056] The load condition of the above aluminum alloy portal frame structure is shown as follows: Figure 5 As shown, the basic wind pressure is 0.25kN / m2, the dead load is 0.014kN / m2, and the live load is 0.05kN / m2; according to the calculation formula of relevant industry specifications, the actual load calculation method is as follows:

[0057] 1.30 Dead Load + 1.50 x 0.70 Live Load 1 + 1.50 Wind Load 2

[0058] After the above calculations, the horizontal displacement of the aluminum alloy portal frame engineering example is obtained, as shown in Figure 6 As shown; the maximum horizontal displacement occurs at the beam-column nodes at both ends; the maximum horizontal displacement in this example is 50 mm, which meets the calculation requirements in Example 1.

[0059] Furthermore, the strength results of this engineering example under load combination are summarized in Figure 7 The maximum stress ratio occurs at the mid-span beam node and the beam-column nodes at both ends. The maximum value of the strength stress ratio is 0.8, and the maximum value of the stable stress ratio is 0.9, both of which are less than 1.0, that is, the strength of the structure meets the requirements.

[0060] It can be seen from the above-mentioned verification demonstration combining actual practice with simulation that the aluminum alloy portal frame designed after verification by the out-of-plane wind resistance stability calculation method of the aluminum alloy portal frame shown in the present invention has the same wind resistance and self-stability as the traditional aluminum alloy portal frame while reducing the overall weight and simplifying its own structure.

[0061] Therefore, the design method of the aluminum alloy portal frame proposed in the present invention has high accuracy and can be used for the design of this type of structure.

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0063] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating the out-of-plane wind stability of an aluminum alloy portal frame, characterized by: The following steps are involved: Step 1: Calculate the equivalent linear load of the aluminum alloy portal frame according to the out-of-plane windward and leeward areas of the aluminum alloy portal frame and the wind load: Where: q is the equivalent linear load generated by the out-of-plane wind load, w k is the basic wind pressure standard value, A w is the area of ​​the gable wall, μ z is the wind pressure height coefficient, N is the number of diagonal braces spans outside the aluminum alloy portal frame, and L is the sum of the lengths of beams and columns of a single span aluminum alloy portal frame; Step 2: Based on the wind load, geometric dimensions, and aluminum alloy properties of the aluminum alloy portal frame, the existing in-plane stiffness calculation formula for the cross grid is used as a reference, and the out-of-plane wind resistance characteristics of the aluminum alloy portal frame structure are considered. The following formula is established to calculate the mid-span displacement of the aluminum alloy portal frame under the equivalent linear load: Where: E x and A x are the elastic model and cross-sectional area of ​​the secondary component, E c and A c are the elastic modulus and cross-sectional area of ​​the diagonal brace, α is the angle between the diagonal brace and the aluminum alloy portal frame beam and column, q is the equivalent wind load of the out-of-plane load, n is the number of half-span grids, x is the length of the grid along the span direction, and y is the length of the grid perpendicular to the span direction; Step 3: Use ABAQUS to establish a large number of out-of-plane analysis models of aluminum alloy portal frames with different spans and arch angles, apply a linear load to the model until the structural stress reaches the design value, and then record the out-of-plane wind displacement limit of the aluminum alloy portal frame at this time; based on the large number of out-of-plane wind displacement limits obtained in the above process, fit the out-of-plane wind instability displacement limit calculation formula of the aluminum alloy portal frame, that is, the out-of-plane wind displacement limit of the aluminum alloy portal frame: Where: [V] is the mid-span out-of-plane displacement limit, h is the height of the aluminum alloy portal frame column, l is the span of the aluminum alloy portal frame, and θ is the angle between the aluminum alloy portal frame beam and column; Step 4: Compare the mid-span displacement data of the aluminum alloy portal frame calculated in step 2 with the displacement limit obtained in step 3. If the former is greater than the latter, the structure is wind-resistant and unstable; otherwise, it is not unstable.

2. The out-of-plane wind stability calculation method of the aluminum alloy portal frame according to claim 1 is characterized by: The aluminum alloy portal frame includes beams, columns, secondary components and diagonal braces, all of which are aluminum alloy components.

3. An aluminum alloy portal frame out-of-plane wind resistance early warning system based on the out-of-plane wind resistance stability calculation method of the aluminum alloy portal frame according to claim 1 or 2, characterized in that: It comprises an aluminum alloy portal frame constructed after calculation by the out-of-plane wind resistance stability calculation method of the aluminum alloy portal frame according to claim 1, and a laser displacement sensor arranged at the top mid-span or ridge position of the aluminum alloy portal frame with a diagonal brace, wherein the laser displacement sensor is used to observe and collect the out-of-plane displacement at the mid-span of the aluminum alloy portal frame and send the actual out-of-plane displacement at the mid-span of the aluminum alloy portal frame to the outside world for comparison with the out-of-plane displacement limit value [V] at the mid-span calculated by the calculation method.

4. The aluminum alloy portal frame out-of-plane wind warning system according to claim 3 is characterized by: It also includes a wireless or wired network transmission module, which sends the mid-span out-of-plane displacement of the aluminum alloy portal frame collected by the laser displacement sensor to the operation terminal for real-time observation. The monitoring frequency of the laser displacement sensor is once a day under normal weather conditions and once an hour under windy weather conditions.

5. The aluminum alloy portal frame out-of-plane wind warning system according to claim 4 is characterized by: Also includes An operation terminal compares the actual mid-span out-of-plane displacement of the received aluminum alloy portal frame with the mid-span out-of-plane displacement limit [V] calculated by the out-of-plane wind resistance stability calculation method of the aluminum alloy portal frame according to claim 1, and issues a preliminary warning when the ratio reaches 0.6, a formal warning when the ratio reaches 0.8, and a severe warning when the ratio reaches 0.95.

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