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GB/T 39794.2-2021: Test method for wind uplift resistance of mental roof - Part 2: Dynamic pressure method
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Test method for wind uplift resistance of mental roof - Part 2: Dynamic pressure method
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GB/T 39794.2-2021
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Basic data | Standard ID | GB/T 39794.2-2021 (GB/T39794.2-2021) | | Description (Translated English) | Test method for wind uplift resistance of mental roof - Part 2: Dynamic pressure method | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | Q17 | | Word Count Estimation | 10,161 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | GB/T 39794.2-2021: Test method for wind uplift resistance of mental roof - Part 2: Dynamic pressure method
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Test method for wind uplift resistance of mental roof - Part 2.Dynamic pressure method
ICS 91.060.20
Q17
National Standards of People's Republic of China
Testing method for wind resistance performance of metal roof
Part 2.Dynamic Pressure Method
Released on 2021-03-09
2022-02-01 implementation
State Administration of Market Supervision and Administration
Issued by the National Standardization Management Committee
Table of contents
Foreword Ⅰ
1 Scope 1
2 Normative references 1
3 Terms and definitions 1
4 Detection principle 1
5 Detection device 2
6 Specimen and installation 3
7 Test 3
8 Test report 6
Appendix A (informative appendix) Plastic film sealing method 7
Foreword
GB/T 39794 "Test Method for Wind-Resistant Performance of Metal Roofing" is divided into 2 parts.
---Part 1.Static pressure method;
---Part 2.Dynamic pressure method.
This part is Part 2 of GB/T 39794.
This section was drafted in accordance with the rules given in GB/T 1.1-2009.
This part was proposed by the Ministry of Housing and Urban-Rural Development of the People's Republic of China.
This part is under the jurisdiction of the National Standardization Technical Committee for Building Curtain Walls, Doors and Windows (SAC/TC448).
Drafting organizations of this section. China Academy of Building Research Co., Ltd., China Building Materials Inspection and Certification Group Suzhou Co., Ltd., Zhuosi Construction
Applied Technology Consultants (Zhuhai) Co., Ltd., Guangdong Academy of Building Research Group Co., Ltd., Jiangsu Province Construction Engineering Quality Inspection
Heart Co., Ltd., Suntex Group Co., Ltd., Henan Academy of Building Research Co., Ltd., China Building Materials Inspection and Certification Group Co., Ltd.
Co., Ltd., Fujian Academy of Building Research Co., Ltd., Altai Construction Engineering Consulting (Shanghai) Co., Ltd., Guangdong Jianlang Five
Gold Products Co., Ltd.
The main drafters of this section. Shi Qing, Wang Hongtao, Qiu Ming, Yan Qiang, Zhu Zhiyuan, Liu Huitao, Lin Kunjian, He Xuan, Jiang Meiqin, Miao Zexian, Feng Yong,
Mu Xiujun, Chen Yiyu, Huang Yiming, Li Min, Cao Yuan, Sun Meifeng, Wang Junyang, Liu Huihua, Yu Yifan.
Testing method for wind resistance performance of metal roof
Part 2.Dynamic Pressure Method
1 Scope
This part of GB/T 39794 specifies the terms and definitions, detection principles, and inspection methods of the dynamic pressure detection method for the wind resistance of metal roofs.
Test device, test piece and installation, test, test report.
This section applies to engineering inspections and product inspections for wind-lift resistance of metal roofs using the dynamic pressure method.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article
Pieces. For undated reference documents, the latest version (including all amendments) is applicable to this document.
GB/T 39794.1 Test method for wind resistance performance of metal roof Part 1.Static pressure method
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Metalroof
It is composed of a metal panel and a supporting system, which is connected to the main structure but does not share the effect of the main structure and the angle with the horizontal direction is less than
75° building envelope.
3.2
Corrugated metalroof
A roof and wall system in which a profiled metal plate is connected to a supporting structure through fixed brackets and fasteners.
3.3
Windupliftresistance
Anti-wind
The ability of the metal roof to resist the upward force generated by the wind load.
3.4
Dynamic pressure
The cyclical fluctuating pressure difference on the surface of the test piece.
3.5
Pressuredifference
The difference between the pressure on the surface of the test piece and the atmospheric pressure.
Note. When the pressure on the surface of the test piece is higher than atmospheric pressure, the pressure difference is positive pressure; otherwise, it is negative pressure.
4 Detection principle
Use the air supply equipment to inflate the lower pressure tank of the metal roof to form a stable positive pressure, and at the same time pump air to the upper pressure tank of the metal roof, and
Through the control device, the periodic undulating negative pressure is generated to form a resultant force that simulates the upward action of the wind load on the metal roof, so as to detect the metal
The ability of the roof to resist wind.
5 Detection device
5.1 The detection device consists of an upper pressure tank, a lower pressure tank, installation frame, air supply equipment, pressure control device, pressure measurement device, and displacement measurement device.
Measuring device and other components (see Figure 1).
5.2 The opening size of the upper and lower pressure tanks should be able to meet the requirements for the installation of the test piece, and should not be less than 3.05m×3.05m. The strength of the pressure tank
The degree should be able to meet the testing requirements. Observation windows should be installed around the pressure tank, and lighting devices should be installed inside. The air outlet of the pressure tank should be installed
Flow baffle.
5.3 The upper and lower pressure tanks should have independent air supply equipment. The air supply equipment should have the ability to apply a specified pressure difference, and the static pressure control device
The setting should be able to adjust the stable air flow, and the dynamic pressure control device should be able to adjust the periodic fluctuating wind pressure, the peak and trough of the fluctuating wind pressure
The value should meet the testing requirements, and the air supply and pressure control capabilities should meet the requirements of Chapter 7.
5.4 The angle between the side of the collecting cover of the upper pressure tank and the horizontal direction is 30°±2°, and the size of the top plate is (610±10)mm×(610±10)mm,
And reserve the air outlet.
5.5 The installation frame should have sufficient rigidity and strength.
5.6 The total pressure measuring tube of the upper pressure tank is composed of 5 independent pressure measuring tubes distributed inside the box. The pressure measuring tube is 6mm in inner diameter.
Copper tubes, of which 4 piezometer tubes are diagonally distributed, and the angle between each piezometer tube and the bottom of the box is 45°, and the distance from the corner of the box is 1000mm,
The fifth piezometric tube is arranged in the center of the upper box, and the ends of all piezometers are located at 180mm from the bottom surface of the box.
5.7 The total pressure measuring tube of the lower pressure tank is also composed of 5 independent pressure measuring tubes distributed inside the tank, and the pressure measuring tube has an inner diameter.
6mm copper pipes, of which 4 piezometer tubes are diagonally distributed, and the angle between each piezometer tube and the bottom of the box is 45°, and is away from the corner of the box
1000mm, the fifth piezometric tube is arranged in the center of the lower box, and the ends of all piezometers are located at 180mm on the upper surface of the bottom of the box.
5.8 The accuracy of the differential pressure sensor should reach 1% of the indicated value, and the measurement response speed should meet the requirements of fluctuating pressure measurement; the accuracy of the displacement meter should reach
To 0.25% of full scale.
6 Specimen and installation
6.1 The test piece should be representative and consistent with the actual project. The profiled metal sheet roof shall include at least 3 spans and 5 panel widths and
Its supporting system. Other metal roofs should include at least one force-bearing unit.
6.2 The materials, specifications and models of the test pieces shall be consistent with the drawings provided by the manufacturer, the installation of the test pieces shall meet the design requirements, and the stress conditions shall be consistent with those provided by the manufacturer.
In accordance with the actual situation, no special attachments or other additional measures should be taken.
6.3 The test piece and the pressure tank should be installed reliably and effectively sealed. The connection and sealing of the test piece and the pressure tank shall not restrict the change of the test piece
shape. For single-laminated metal sheet roofs, plastic films with a thickness of no more than 0.15mm should be used for sealing before testing. Plastic film dense
See Appendix A for the sealing method.
7 Detection
7.1 Preparation before testing
7.1.1 The maximum detection pressure difference can be allocated according to the following conditions.
a) The maximum detected pressure difference should not be less than the wind load design value.
b) Determine the pressure difference between the upper and lower surfaces of the metal roof according to the actual project. The sum of the absolute value of the maximum value of positive pressure and negative pressure should be equal to the maximum
Check the pressure difference.
c) The positive pressure should be 15% of the maximum detection pressure difference, and the maximum negative pressure should be 85% of the maximum detection pressure difference.
d) In the case that the design value of wind load on the test piece cannot be determined, the ultimate wind pressure of the test piece can be obtained through the test of GB/T 39794.1.
One half of this pressure is used as the maximum detection pressure value. After the test piece is installed, it can only be checked after it meets the requirements of the design drawing
Perform testing.
7.1.2 It is advisable to install a displacement meter on the main force-bearing members such as purlins and panels, which may have large displacements, to measure the front and back changes.
Affected.
7.1.3 After the test piece is installed, it can be tested only after it meets the requirements of the design drawing.
7.1.4 Appropriate safety measures should be taken during testing.
7.2 Testing procedures
A stable positive pressure is applied to the lower pressure tank of the test piece, while a fluctuating negative pressure is applied to the upper pressure tank. Wait until the pressure of the lower box is stable, and
After the fluctuating pressure of the box body reaches the corresponding value, it starts to record the number of fluctuations. The range of fluctuating negative pressure should be the maximum negative pressure multiplied by the corresponding stage
The proportional coefficient, the range of negative pressure fluctuation and the number of fluctuations should meet the requirements of Table 1 and Figure 2.The period of fluctuating pressure difference is (10±2)s, as shown in Figure 3.
Show. Observe and record the pressure stages, conditions and parts of the specimens that are damaged, and take pictures of the damaged parts.
Table 1 Fluctuation pressure requirements
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