AS 4040.3:2018 pdf free.Methods of testing sheet roof and wall cladding Method 3: Resistance to wind pressures for cyclone regions.
4.2 Loading system
The test to resist cyclonic wind pressures is concerned with the interaction between the cladding and the fasteners and the deformation of the cladding. For continuous cladding (i.e. not single span), this necessitates a multi-span test specimen. Cladding extending over three supporting members can satisfactorily represent a double end-span condition.
A commonly used loading medium for this type of test is an air box or air chamber where
the cladding forms the top surface of the box. The air chamber is pressurized thus providing
a uniform load across the surface of the cladding. Oscillating valves are used to provide the
pressure cycles.
For concealed fixed cladding systems, an air box without a continuous membrane (either positive or negative pressure) shall be used for testing.
Inflatable air bag loading systems, or point or line loading systems cannot be used for testing of concealed fixed cladding as they can impose constraints on the test specimen, hinder the cladding deformation, and lead to un-conservative results.
NOTE: Seccombe et al (1996) details lower failure pressures for secret fixed cladding tested in an air chamber compared with air bag method.
The following apply to the loading system:
(a) Pressure or loading equipment shall be capable of delivering at least 5% greater than the peak pressure determined in Table 1.
(b) For each test sequence, the upper limit of each pressure sequence shall be not less than the target value.
(c) The lower limit shall be not greater than 10% of the upper load limit of the same load sequence.
The rate of load cycling shall be less than 3 Hz.
4.3 Measuring devices
Deflections shall be determined by means of a device capable of measuring to an accuracy of not less than 0.05 mm. Pressures or loads shall be determined to an accuracy of not less than 5%.
NOTE: An accuracy of 5% would normally be achieved by means of a device capable of measuring to an accuracy of 1% of full scale.
5 TEST SPECIMEN
The test specimen shall be as specified in AS 4040.0.
6 PROCEDURE FOR TESTING WALL CLADDING SYSTEMS
6.1 Loading
6.1.1 Design pressures
Design wind pressures for strength limit state and serviceability limit state may be calculated from the relevant wind speeds V and V listed in AS/NZS 11 70.2 for the appropriate cyclone regions. The design pressure shall be derived from a combination of internal positive pressure and external negative pressure, including local pressure factors where appropriate, for the particular part of the wall being tested.
Alternatively for residential construction, the design net wall pressures shall be obtained directly for the C wind classifications from AS 4055.AS 4040.3 pdf download.