GB/T 39794.1-2021Test method for wind uplift resistance of metal roof—Part 1:Static pressure method (English PDF)

2.1 Windupliftresistance

Windupliftresistance The ability of the roof to resist the upward force generated by the wind load.

2.2 Permanentdeformation

Any unrecoverable shape change that still exists after the metal plate or exposed roof panel is removed by the external force. This unrecoverable shape change Only through the use of specific equipment and mechanical methods can it be eliminated.

4.1 Composition of testing device

The detection device is composed of a pressure box, an air supply device, a pressure measuring device, etc. (see Figure 1).

4.2 Pressure tank

Able to apply pressure on the bottom of the metal roof (specimen) and maintain a preset pressure level. The size of the pressure tank should not be less than 7.3m× 3.7m, it consists of 200mm wide steel pipes to form the peripheral structure, and a minimum thickness of 4.8mm protective steel plate to form the bottom structure, 150mm wide The steel beams are arranged in the middle of the pressure box at intervals of 0.6m parallel to the side with a length of 7.3m. The protective steel plate at the bottom of the pressure tank, and The lower steel beams are spot welded together and welded to the channel steel on the inner side of the periphery. Fix the sample frame above the pressure tank and seal it. its The pressure box made of other shapes, sizes, and materials can firmly support the sample frame and can also be used.

4.3 Air supply device

It is composed of a gas source and a 100mm diameter pipeline with a branch pipe structure. At the bottom of the pressure tank, pass through the bottom steel plate, and distribute 4 etc.

Spaced air inlets. The gas source should adopt a turbocharger device, which can generate an air flow of at least 17m³/min. You can also use it He can reach the required elevated pressure gas source or a device with the same ability.

4.4 Pressure measuring device

The opening at the bottom of the pressure tank is used to connect a pressure gauge, and a liquid-filled pressure gauge is used to directly read the pressure value with an accuracy of 0.1kPa. You can also use it He can meet the accuracy of the device.

5.1 Test piece

5.1.1 The installed metal roof (test piece) should be representative and consistent with the actual project.

5.1.2 Roof components may include purlins, metal plates, daylighting panels, flat plates, vapor barrier materials, gas barrier materials, thermal insulation materials, roof coverings and all Related fixings, etc. The width of the test piece shall include at least 3 full-width metal plates. Test 1 test piece.

Note: The representative of the test piece includes the thickness, material, construction method of the metal plate, the size and thickness of the fixings, the insulation material, and the type of covering material.

5.2 Test piece installation

5.2.1 The installation of the test piece shall be carried out in accordance with the requirements of the product manual or installation instruction.

5.2.2 The structural parts (such as purlins) are installed on the sample frame, the fixing base is fixed to the structural parts (such as purlins), and then the metal plate is laid. in Before the metal plate is installed, a polyethylene film with a thickness of not less than 0.15mm can be used and placed in the structure after pleating in the direction parallel to the length of the metal plate.

On the parts, make the air pressure evenly act on the bottom of the metal plate. Place a thin EPDM rubber sheet (or similar material) that is larger than the fixed seat Between the membrane and the fixing seat, a fixing piece is used to pass through the rubber sheet to fix the fixing seat on the structural part.

5.2.3 It is used to fix fixed seats, metal plates, roof covering materials, roof insulation materials and all other solid materials used for structural or roof panel components.

The fixed parts should be installed according to the requirements, and no parts will be damaged. The fixture should penetrate the structure or board and reach the recommended minimum drilling length. So The use of adhesive should be carried out according to the manufacturer's construction method.

5.2.4 After the metal plate is installed, occlude the plate seam. Roofing systems usually contain structural layers such as thermal insulation materials.

When the anti-wind lift performance is affected, the structural layer may not be installed during the inspection process.

6.5 Step by step pressurization

6.5 Maintain the pressure rate of (0.07±0.05) kPa/s to reach the next pressure level, if the pressure rise rate cannot be maintained to reach the next pressure level In the case of force level, the rate of rise between each pressure level should be kept uniform, and the pressure should be maintained for 60s at each pressure level. Keep for 60s After pressure, exhaust the air to zero. Check the sample again for permanent deformation, and confirm that it meets the requirements of 7.3, repeat the test procedure, and increase each time The pressure difference is 0.7kPa (see Figure 2).

Figure 2 Schematic diagram of the pressurization procedure 6.6 Carry out the test as described in 6.5 until the test piece is damaged, or cannot reach a higher pressure level, or reach the pressure value required by the client.

If it does not meet the requirements of 7.3 or fails to maintain the pressure level for 60s, the test is terminated.