A method for deepening purlin of special-shaped curved roof

Abstract

The present application relates to a kind of purlin deepening method of special-shaped curved surface modeling roof, including step one: purlin calculation preparation;Step two: create wind pressure measuring point and associate wind pressure;Step three: specify purlin arrangement limit condition;Step four: specify purlin N group initial arrangement scheme;Step five: by purlin endpoint nearest measuring point wind pressure fitting purlin calculation wind pressure;Step six: calculate and judge whether the safety factor of each purlin is less than the minimum safety factor set;Step seven: judge whether the safety factor of each purlin is greater than the minimum safety factor set;Step eight: using bionic algorithm to standard deviation as objective function redivides N group purlin arrangement;Step nine: judge whether to reach stop optimization condition;Step ten: judge whether the purlin mean of optimal standard deviation is too large.The present application realizes the in-situ data extraction based on space model to calculate the safety factor of each purlin, reaches the goal of purlin safety factor uniformity.

Description

Technical Field

[0001] This invention relates to a design method for cold-formed thin-walled purlins for building roofs, specifically a method for refining purlins for irregularly shaped curved roofs. Background Technology

[0002] In the field of metal roofing design, structural safety design is a crucial task that determines the success or failure of the roofing design. The effectiveness of designing the load-bearing system of the roof directly impacts the reliability of the metal roof within its design service life. For conventional sloping metal roofs, such as industrial plant projects, the regular shape of the roof and the regular load distribution and main structure shape allow for the achievement of uniform structural load-bearing parameters through design calculations, such as purlin spacing, specifications, and orientation, ultimately resulting in a uniform safety factor for all parts of the roofing system. However, for irregularly shaped curved roofs, such as those in stadiums, transportation hubs, and exhibition halls, the varying wind loads and different shapes of the main load-bearing structures make it exceptionally difficult to design roof load-bearing parameters with a uniform safety factor.

[0003] To ensure the safety and reliability of irregularly shaped curved metal roof structures, current design teams generally employ conservative calculation methods. They divide the entire roof into key areas based on the unevenness of wind loads, obtaining the highest positive and negative wind pressure values. These values ​​are then combined with other loads, and the purlin spacing, specifications, and orientation are designed for each area. However, because roof slope, wind load, and purlin span vary significantly across irregularly shaped roofs, the representativeness of these areas depends heavily on the structural expertise of the purlin designers. The currently used purlin calculations may not be representative of the areas, leading to safety risks in some areas and excessive safety margins in many others. In other words, the purlin safety factor is uneven across the entire irregularly shaped curved roof.

[0004] Search results: 1. A purlin structure reinforcement design method [CN202210157896]: This invention forms an initial design model based on several target values ​​of the purlin structure, preset geometric information and boundary physical parameters, and then uses multi-condition topology optimization technology to obtain the topology optimization form of the purlin structure, thereby realizing the reinforcement design of the purlin structure in the photovoltaic system without increasing the cost. 2. Roof purlin generation method, device, computer equipment and storage medium [CN202010076331]: This invention automatically generates roof purlins on the plane where the eaves beam or the inclined eaves beam is located by a computer by presetting the initial purlin sequence and spacing.

[0005] 3. One-way purlin system, two-way purlin system and roof [CN201520973070]: This invention provides a one-way purlin system and a two-way purlin system that can be arranged sequentially at intervals and in parallel according to specified rules, which are more suitable for flat roof purlin systems. Summary of the Invention

[0006] The present invention aims to overcome the defects of the prior art and provide a method for refining purlins for irregular curved roofs, solving the problems of uneven safety factor calculation and uneconomical design of purlins in traditional irregular curved roofs.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows: A method for refining purlins in an irregularly shaped curved roof, characterized by comprising the following steps: Step 1: Purlin Calculation and Preparation; Step 2: Create wind pressure measurement points and associate them with wind pressure; Step 3: Specify the purlin arrangement constraints; Step 4: Specify the initial layout plan for N sets of purlins; Step 5: Fit the wind pressure of the purlin to the wind pressure at the nearest measuring point at the purlin end; Step 6: Calculate and determine whether the safety factor of each purlin is less than the set minimum safety factor; Step 7: Determine whether the safety factor of each purlin is greater than the set minimum safety factor; Step 8: Use a biomimetic algorithm to re-divide the N groups of purlin arrangements with standard deviation as the objective function; Step 9: Determine if the conditions for stopping optimization have been met; Step 10: Determine if the purlin mean with the optimal standard deviation is too large.

[0008] The method for refining the purlins of the irregular curved roof is characterized in that: the purlin calculation preparation in step one includes: collecting original design data, creating the main structural model, and calculating the roof dead load, live load and snow load; Step two specifically involves creating wind pressure measurement points on the roof skin model using the wind tunnel model points from the wind tunnel test report. Each wind pressure measurement point corresponds to a maximum positive wind pressure and a maximum negative wind pressure. The wind tunnel test report will list the wind pressure measurement point data on the roof skin model. Based on the wind pressure test data from different angles, the wind tunnel test report will provide the maximum positive wind pressure value and the maximum negative wind pressure value for each measurement point. The wind pressure measurement points on the skin model are spatial geometric point data, and each point is associated with the maximum positive wind pressure value and the maximum negative wind pressure value, which facilitates subsequent calculations of the purlin bearing capacity. Step 3 is as follows: For irregular curved roofs, the vertical projection of the purlins is parallel and continuous, and the purlins are connected end to end. This is a common requirement for the drainage direction and installation conditions of the upper roof system. As a special case, the arrangement constraint condition is included in the purlin spacing optimization algorithm. If there are other arrangement constraint rules, the corresponding constraint conditions can be preset. Step four is as follows: For the roof surface curved surface, i.e. the data collected in step 1, select N groups of M vertical planes with a spacing not less than a certain constant. Each plane forms X sequential intersection points with the main structure. According to the constraint conditions, all purlins are parallel in vertical projection. Any vertical plane can be used. Each plane can form an intersection point with the main structure. Since the support point of the purlin is in the main structure, the sequential intersection points can be used as the two endpoints of the purlin in turn. Connect the X intersection points sequentially to form X-1 purlins; this completes the purlin arrangement. The spacing between the purlin endpoints can be automatically calculated as the purlin span. The tilt angle of the entire purlin can be calculated by calculating the slope at both ends of the purlin. Similar data can be used as parameters for in-situ calculation of the purlins. Step five specifically involves finding the nearest wind pressure measuring points at both ends of each purlin, and calculating the average positive and negative wind pressure values ​​from the two measuring points as the average positive and negative wind pressure values ​​of the purlin. Using the average wind pressure value from measuring points near both ends as the purlin wind pressure value is a reasonable approximation. If the distance between the purlin ends and the wind pressure measuring points is far, a surface fitting method can be used to predict the wind pressure values ​​at the two ends as the basis for calculating the purlin wind pressure value. Step six specifically involves calculating the safety factor for each purlin. If the safety factor of any purlin is less than the set minimum safety factor, the purlin arrangement generated by that group of vertical planes is discarded. If the purlin safety factor is less than the set minimum safety factor, it means that the purlin structural resistance value is less than the roof load effect value, which is unsafe. If the purlin spacing is too large, the purlin arrangement should be discarded. Step seven is as follows: If the safety factor of each purlin is greater than the set minimum safety factor, calculate the mean and standard deviation of the safety factors of the M*(X-1) purlins in the group, compare the standard deviations of each group, and discard the half of the data with the larger standard deviation; under the premise of ensuring the safety of the purlins, evaluate the safety factor of the currently divided purlin arrangement. If the standard deviation is too large, it means that the purlin safety factor is too discrete and the division data is unreasonable, and it should be discarded. Step eight specifically involves: re-dividing the remaining relatively reasonable Y-group planes in the N groups according to the mean and standard deviation data and the corresponding trends; using a biological simulation algorithm, with the standard deviation of the purlin safety factor as the objective function and the purlin arrangement scheme as the biological population of the simulation algorithm, minimizing the standard deviation of the purlin safety factor in the fine-tuning movement of each group of vertical planes; Step nine specifically involves stopping the search optimization when the standard deviation is less than a fixed value after a certain number of calculations or when the difference between the optimal standard deviations of two consecutive iterations is less than a fixed value. Step 10 is as follows: If the designer believes that the average safety factor is too large, reduce one face and recalculate until the safety factor of all purlins is close to the set minimum safety factor and the standard deviation is the smallest.

[0009] The method for refining the purlins of irregularly shaped curved roofs is characterized by the following: Step 1, the collection of original design data, includes: collecting main structural drawings, wind tunnel test reports, roof construction layers, basic wind pressure, basic snow pressure, roof surface model, purlin cross-section and material information; creating the main structural model means that the main structural model is the load-bearing structure of the purlins. When the purlins are calculated as a simply supported beam load-bearing model, the supports are fixed on the main structural model, and the span data of the purlins can be obtained by combining the main structure; calculating the roof dead load, live load and snow load means: calculating the roof dead load through the roof construction layers, and calculating the live load and snow load through the roof type and in combination with the specifications.

[0010] The beneficial effects of this invention are as follows: Compared with prior art 1, this application adopts a different optimization method. The design principle of the purlin with irregular curved surface has certain constraints (such as the arrangement direction relationship between purlins and the continuity of purlins). At the same time, it uses the in-situ data of the entire roof structure to participate in the calculation, which has obvious integrity.

[0011] Compared with prior art 2, the differences in this application are: parameters such as purlin spacing are continuously optimized through algorithms to achieve a purlin arrangement with uniform safety; the design, calculation and optimization of curved purlins are significantly different from the simple fixed rule eaves purlin arrangement.

[0012] Compared with prior art document 3, this application provides an automatic optimization method and a purlin data extraction and in-situ calculation method based on a spatial model that are different from those in prior art document 3.

[0013] This invention enables in-situ data extraction based on spatial models (such as purlin spacing, span, and wind load) to accurately calculate the safety factor of each purlin; at the same time, using the standard deviation of the safety factors of all purlins as the objective function, biomimetic algorithms (such as ant colony algorithm, genetic algorithm, etc.) can be used to optimize the purlin arrangement to achieve the goal of uniform purlin safety factors. Attached Figure Description

[0014] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments: Figure 1 This is a flowchart illustrating the application process.

[0015] Figure 2 This is a schematic diagram of the main structure and building facade.

[0016] Figure 3 A schematic diagram of adding wind pressure measurement points to the building facade.

[0017] Figure 4 This is a schematic diagram of a surface divided by M parallel planes with unequal spacing.

[0018] Figure 5 A schematic diagram showing the arrangement of purlins to connect the intersection points of the dividing lines.

[0019] Figure 6 This diagram illustrates the iterative process of purlin arrangement using a biomimetic algorithm for fine-tuning spacing.

[0020] Figure 7 A diagram illustrating the recalculation to obtain a better average safety factor by reducing the number of purlins. Detailed Implementation

[0021] like Figure 1 As shown: A method for refining the purlins of an irregularly shaped curved roof, comprising: Step 1: Purlin Calculation and Preparation.

[0022] This includes collecting original design data (including main structural drawings, wind tunnel test reports, roof construction layers, basic wind pressure, basic snow pressure, roof skin shape model, purlin cross-section and material information, etc.). This step is consistent with the design method of conventional irregular curved roof purlins. Collecting original design data helps to understand the constraints and limitations of purlin arrangement, and also provides the necessary data for calculating the purlin safety factor.

[0023] like Figure 2 As shown: Create the main structure model; the main structure model is the load-bearing structure of the purlins. When the purlins are calculated as a simply supported beam, the supports are fixed on the main structure model. The span data of the purlins can be obtained by combining the main structure model.

[0024] Calculate the roof dead load, live load, and snow load; calculate the roof dead load by roof construction layers, and calculate the live load and snow load by roof type and in conjunction with specifications; this step is consistent with the calculation of conventional roof systems. Dead, live, and snow loads are important components participating in load combinations and can be calculated using conventional data, with a relatively weak correlation to spatial model data.

[0025] like Figure 3 As shown: Step 2 involves creating wind pressure measurement points on the roof skin model using the wind tunnel model points from the wind tunnel test report. Each wind pressure measurement point corresponds to a maximum positive wind pressure and a maximum negative wind pressure. The wind tunnel test report will list the wind pressure measurement point data on the roof skin model. Based on the wind pressure test data from different angles, the wind tunnel test report will provide the maximum positive wind pressure value and the maximum negative wind pressure value for each measurement point. The wind pressure measurement points on the skin model are spatial geometric point data, and each point is associated with the maximum positive wind pressure value and the maximum negative wind pressure value, which facilitates subsequent calculations of the purlin load-bearing capacity.

[0026] Step 3: Specify purlin constraints. For irregularly shaped curved roofs, the parallel and continuous arrangement of purlins in vertical projection (purlins connected end to end) is a common requirement for the drainage direction and installation conditions of the upper roof system. In this invention, the arrangement constraint is used as a special case in the purlin spacing optimization algorithm. If there are other arrangement constraint rules, the corresponding constraint conditions can be preset.

[0027] like Figure 4 , 5 As shown: Step 4: Select N groups of M vertical planes (the spacing can be unequal) with a spacing of not less than a certain constant (such as 400mm) for the curved surface of the roof skin (collected in Step 1). Each plane forms X sequential intersection points with the main structure. According to the constraints in Step 5, all purlins are parallel in vertical projection. Any vertical plane can be used. Each plane can form an intersection point with the main structure. Since the support point of the purlin is in the main structure, the sequential intersection points can be used as the two ends of the purlin in turn.

[0028] Connect the X intersection points sequentially to form X-1 purlins; this completes the purlin arrangement. The spacing between the purlin endpoints can be automatically calculated as the purlin span. The tilt angle of the entire purlin can be calculated by calculating the slope at both ends of the purlin. Similar data can be used as parameters for in-situ calculation of the purlins. Step 5: Locate the nearest wind pressure measuring points at both ends of each purlin, and calculate the average positive and negative wind pressure values ​​from the two measuring points as the average positive and negative wind pressure values ​​of the purlin. Using the average wind pressure value from measuring points near both ends as the purlin wind pressure value is a reasonable approximation. If the distance between the purlin ends and the wind pressure measuring points is far, the wind pressure values ​​at the two ends can be predicted using the surface fitting method as the basis for calculating the purlin wind pressure value.

[0029] Step 6: Calculate the safety factor for each purlin. If the safety factor of any purlin is less than the set minimum safety factor (e.g., 1.0), the purlin arrangement generated by that group of vertical planes should be discarded. The calculation method can be based on the "Technical Specification for Cold-Formed Thin-Walled Steel Structures" and the "Technical Specification for Portal Frame Light Steel Structures". If the purlin safety factor is less than the set minimum safety factor, it means that the purlin structural resistance value is less than the roof load effect value, which is unsafe. If the purlin spacing is too large, the purlin arrangement should be discarded.

[0030] Step 7: If the safety factor of each purlin is greater than the set minimum safety factor, calculate the mean and standard deviation of the safety factors of the M*(X-1) purlins in this group. Compare the standard deviations of each group, and discard the half of the data with the larger standard deviation. Under the premise of ensuring purlin safety, evaluate the safety factor of the currently divided purlin arrangement. If the standard deviation is too large, it indicates that the purlin safety factors are too dispersed, the data division is unreasonable, and they should be discarded.

[0031] like Figure 6 ,7 As shown: Step 8 involves re-dividing the remaining N groups of relatively reasonable Y-group planes according to the mean and standard deviation data and the corresponding trends. This update iteration can refer to ant colony algorithms, genetic algorithms, etc. Using a biological simulation algorithm, the standard deviation of the purlin safety factor is used as the objective function, and the purlin arrangement scheme is used as the simulated biological population. In the fine-tuning and movement of each group of vertical planes, the minimum standard deviation of the purlin safety factor is achieved.

[0032] Step 9: Stop the search optimization when the standard deviation is less than a fixed value after a certain number of calculations, or when the difference between the optimal standard deviations of two consecutive iterations is less than a fixed value. This step is the condition for stopping optimization.

[0033] Step 10: If the designer believes that the average safety factor is too large, reduce one face and recalculate until the safety factors of all purlins are close to the set minimum safety factor and the standard deviation is the smallest.

Claims

1. A method for refining purlins in an irregularly shaped curved roof, characterized in that... It includes the following steps: Step 1: Purlin Calculation and Preparation; Step 2: Create wind pressure measurement points and associate them with wind pressure; Step 3: Specify the purlin arrangement constraints; Step 4: Specify the initial layout plan for N sets of purlins; Step four specifically involves: for the curved surface of the roof skin, i.e. the data collected in step 1, selecting N groups of M vertical planes with a spacing not less than a certain constant, and each plane forming X sequential intersection points with the main structure; According to the constraints, all purlins are parallel in vertical projection. Any vertical plane can be used, and each plane can intersect with the main structure. Since the support points of the purlins are in the main structure, the sequential intersection points can be used as the two ends of the purlins. Connect the X intersection points sequentially to form X-1 purlins; this completes the purlin arrangement. The spacing between the purlin endpoints can be automatically calculated as the purlin span. The tilt angle of the entire purlin can be calculated by calculating the slope at both ends of the purlin. Similar data can be used as parameters for in-situ calculation of the purlins. Step 5: Fit the wind pressure of the purlin to the wind pressure at the nearest measuring point at the purlin end; Step 6: Calculate and determine whether the safety factor of each purlin is less than the set minimum safety factor; Step six specifically involves calculating the safety factor for each purlin. If the safety factor of any purlin is less than the set minimum safety factor, the purlin arrangement generated by that group of vertical planes is discarded. Step 7: Determine whether the safety factor of each purlin is greater than the set minimum safety factor; Step seven is as follows: If the safety factor of each purlin is greater than the set minimum safety factor, calculate the mean and standard deviation of the safety factors of the M*(X-1) purlins in the group, compare the standard deviation of each group, and discard the half of the data with the larger standard deviation. Step 8: Use a biomimetic algorithm to re-divide the N groups of purlin arrangements with standard deviation as the objective function; Step eight specifically involves: re-dividing the remaining relatively reasonable Y-group planes in the N groups according to the mean and standard deviation data and the corresponding trends; using a biological simulation algorithm, with the standard deviation of the purlin safety factor as the objective function and the purlin arrangement scheme as the biological population of the simulation algorithm, minimizing the standard deviation of the purlin safety factor in the fine-tuning movement of each group of vertical planes; Step 9: Determine if the conditions for stopping optimization have been met; Step 10: Determine if the purlin mean with the optimal standard deviation is too large.

2. The purlin detailing method for irregular curved roofs according to claim 1, characterized in that: Step 1, the preparation for purlin calculation, includes: collecting original design data, creating a main structural model, and calculating roof dead load, live load, and snow load. Step two specifically involves creating wind pressure measurement points on the roof skin model using the wind tunnel model points from the wind tunnel test report. Each wind pressure measurement point corresponds to a maximum positive wind pressure and a maximum negative wind pressure. The wind tunnel test report will list the wind pressure measurement point data on the roof skin model. Based on the wind pressure test data from different angles, the wind tunnel test report will provide the maximum positive wind pressure value and the maximum negative wind pressure value for each measurement point. The wind pressure measurement points on the skin model are spatial geometric point data, and each point is associated with the maximum positive wind pressure value and the maximum negative wind pressure value, which facilitates subsequent calculations of the purlin bearing capacity. Step 3 is as follows: For irregular curved roofs, the vertical projection of the purlins is parallel and continuous, and the purlins are connected end to end. This is a common requirement for the drainage direction and installation conditions of the upper roof system. As a special case, the arrangement constraint condition is included in the purlin spacing optimization algorithm. If there are other arrangement constraint rules, the corresponding constraint conditions can be preset. Step five specifically involves finding the nearest wind pressure measuring points at both ends of each purlin, and calculating the average positive and negative wind pressure values ​​from the two measuring points as the average positive and negative wind pressure values ​​of the purlin. Using the average wind pressure value from measuring points near both ends as the purlin wind pressure value is a reasonable approximation. If the distance between the purlin ends and the wind pressure measuring points is far, a surface fitting method can be used to predict the wind pressure values ​​at the two ends as the basis for calculating the purlin wind pressure value. Step nine specifically involves stopping the search optimization when the standard deviation is less than a fixed value after a certain number of calculations or when the difference between the optimal standard deviations of two consecutive iterations is less than a fixed value. Step 10 is as follows: If the designer believes that the average safety factor is too large, reduce one face and recalculate until the safety factor of all purlins is close to the set minimum safety factor and the standard deviation is the smallest.

3. The purlin detailing method for irregular curved roofs according to claim 2, characterized in that: The collection of original design data in Step 1 includes: collecting the main structural drawings, wind tunnel test reports, roof construction layers, basic wind pressure, basic snow pressure, roof skin model, purlin cross-section and material information; creating the main structural model means that the main structural model is the load-bearing structure of the purlins. When the purlins are calculated as a simply supported beam, the supports are fixed on the main structural model. The span data of the purlins can be obtained by combining the main structural model; calculating the roof dead load, live load and snow load means: calculating the roof dead load through the roof construction layers, and calculating the live load and snow load through the roof type and in combination with the specifications.

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