These objectives are based on the premise that the sample is a faithful reproduction of the proposed design and with the test amendments, a sample of the wall that will be constructed onto the building within the construction tolerances of the structural elements of the building.
A full-scale prototype has the advantage that performance of actual materials in the façade, interaction at joints and fixing points, and visual appearance can be critically assessed. Modifications are permitted as past of the testing development, and is usually identified at the Preliminary Test stages. It is important the modifications are documented so that they are incorporated in the 'as-built" façade.
Principle of Test
A sample of the building façade forms one face of an externally mounted chamber and is sealed at its perimeter to form a pressure chamber. The pressure chamber may be internally or externally mounted depending on requirements of the owner.
Test Sequence
Preliminary test comprising a static pressure loading of half the positive and negative structural design test pressures followed by a preliminary water test under static and cyclic pressures. Preliminary tests are generally conducted prior to the official test day to identify and eradicate flaws in the façade.
The façade is then successively subjected to
Additional tests may also include
A data acquisition system providing real time nodal displacement values and calculated deflection data and span deflection ratios are essential in the Structural Loading Test. They enable the testers to literally see the structural movements as the loading increases and compare the limiting span deflection ratios on the fly.
As a safety issue, real time data empowers the testers to abort a pressure loading sequence should any member or glazing behave at dangerous, non-recoverable levels. Displacements transducers located at the brackets or clips provide additional information to understand the behavior of anchor points especially where oversized holes are drilled to facilitate fixing.
Displacements are measured at all positive and negative pressure sequence steps as shown:
The air infiltration test is a measure of air leakage across the sample area. If openable windows are included in the sample, the leakage across is sometimes determined separately and reported in terms of "crack" length of window. This condition may apply when the major area of the sample consists of openable windows.
The sample is prepared by sealing the facade with an impervious film. If this is not practical, all joints, weep holes and glazing or sealant lines of the test façade are sealed with air impervious adhesive tape.
The sealing of the test sample may be omitted if the total air loss through the sample is less than the limit and actual figures of air losses are not required.
If the sample is sealed and individual losses through each element is required, the air infiltration test is repeated with portions of the sealant removed successively.
The façade is subjected to the air infiltration test pressure as specified by the owner or taken as + 150 Pa and -150 Pa. A suitable flow measuring device, usually an orifice plate located between the fan and the sample is used.
Differential pressure measured across the orifice plate gives the corresponding volumetric leakage rate of the sample at the nominated static chamber pressure.
The test façade is exposed to a simulated environmental condition relevant to the geographical location and exposure of the building. Three factors relating to the water penetration test are:
Static Water Penetration Test subjects the façade to water sprayed continuously and completely over the exterior face at a rate of not less than 0.05 l/s per meter area of the facade, while maintaining a static chamber pressure of 300 Pa.
At the start of the test, the water is sprayed for 5 minutes with zero air pressure. This is followed by 15 minutes at test pressure. The internal surface of the façade is inspected during the water spray operation and for 5 minutes after the water spray has stopped and there is zero air pressure on the façade.
Cyclic Water Penetration Test subjects the façade to water sprayed continuously and completely over the exterior face at a rate of not less than 0.05 l/s per meter area of the façade. Three stages of cyclic air pressure are successively exerted onto the façade exterior face with a 2 minute interval between stages: Stage 1 : 150 to 300 Pa Stage 2 : 300 to 600 Pa Stage 3 : 0.3Wp to 0.6Wp Pa (where Wp is the structural test pressure)
The applied test pressure is varied between the specified limits with a cycle time of 3 to 5 seconds. Observation of the internal surfaces of the façade is carried out during the water spray operation and for 5 minutes after the water spray has stopped during which there is zero air pressure on the façade.
Dynamic Water Penetration Test (AAMA 501.1.83) uses a wind generator such as an aircraft engine with a 4m diameter propeller to simulate wind driven rain at speed of 55km/h and produces a minimum pressure of 137 Pa. The aircraft engine is run at idle speed without the operation of water sprays. When the desired aircraft rotational speed is achieved, the façade is sprayed continuously and completely over the exterior face at a rate of not less than 0.05 l/s per meter area of the façade. Observation of the internal surfaces of the façade is carried out during the water spray operation and for 5 minutes after the water spray has stopped during which there is zero air pressure on the façade.
The restraint is subjected to a tensile load applied orthogonally and horizontal to the sample for a period of 10 seconds. The tensile load is applied horizontally and to the left and right of the sample for a period of 10 seconds.
The owner will designate areas of the sample where seals are to be removed or cut by knife to simulate long term degradation of the sample.
Following which a cyclic water penetration test is carried out. The sample is observed for water penetration after the seals have been removed.
In this part of the test, there is no performance requirement unless specified by the owner.
The façade is displaced in the plane of the sample for n cycles at a period of T for a distance of +/- Wmm from the original setting position. The values of n, T and W shall be specified and based on the serviceability and ultimate limit states appropriate to the geographical region.
One of the reaction beams is selected by the owner as a seismic loading floor. This beam is capable of sliding back and forth to simulate lateral seismic motion. The façade support brackets is attached to the moveable beam. Lateral displacements of the sample are measured as the relative displacement between the lateral fixed support and moveable beam.
The sample shall not collapse during or after the seismic test at serviceability and ultimate limit state displacements. Any damage to the seals, members or panels are noted. Immediately following the seismic test, a cycle water penetration test is performed and used as criteria for acceptance.
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