COP v3.0:structural-testing; test-requirements

17.2 Test Requirements 

17.2A Uniformly distributed Load (UDL)

  1. Serviceability tests:
    1. Deflection under load, (span/120) + p/30 where p is the maximum distance between fasteners on the support structure. (Informative for roofing, Normative for cladding), or by
    2. Permanent deformation or cracking around fastener head, or de-indexing or de-clipping of clip fastened profiles. Serviceability failure of clip fastened products may occur when a clip disengages from the central rib, but weathertightness of the lap is not affected and roof can continue to resist increased loads.
  2. Strength tests.
    Strength tests are defined as: sheet unable to resist further loads i.e. pull-off from clips, buckling, tearing or pull-through of fasteners.

    17.2B Point Load

    1. Resistance to point load on the pan, or to two ribs of narrow profiles,at the weakest point.
    2. Residual deflection after imposition of serviceability load, and application of strength load
    3. Resistance to point load on a single rib at the weakest point.
    4. Residual deflection after imposition of serviceability load, and application of strength load

    Load is applied in a downwards direction through a rubber faced pad. The weakest point is generally mid span at rib/pan adjacent to underlap.

      17.2.1 Supporting Structure and Equipment 

      17.2.1A Uniformly Distributed Load (UDL)

      The design of the support system for wind load should consist of a rigid frame airbox, sealed on the bottom and four sides. A fan or blower is required, capable of controlling and maintaining the required test pressure, and pressure measuring devices. The deflection can be measured using several differential displacement transducers and traced and recorded coincidentally with the increasing load. Purlin and end wall positions can be changed to test for multiple spans of different dimensions.

      The use of airbags rather than air pressure is not endorsed by the MRM COP

      17.2.1B Point Load

      For point load testing, a means of applying and measuring a continuously increasing load is positioned above the part of the material being tested. 

      17.2.2 Test Set-up 

      For tests to have value, testers should pay attention to the number of specimens, width of the testing sections, and the number of spans.

      17.2.2.1 Number of Specimens 

      For new testing, at least two sets of specimens should be provided for each span-fastener combination. Three is preferred as it results in a higher confidence factor. At least three different spans must be tested, and four is preferred as it gives a more accurate gradient to load-span graphs. For confirmatory testing to review previous test results, smaller sample sizes are acceptable providing results are consistent with previous tests.

      17.2.2.2 Width of Specimen 

      The width of a model or the test section of a lapped or interlocking system must be the width represented by at least two sheet side laps.  The total width of the testing rig (2.1 m) must be covered by the test sample or other material.

      17.2.2.3 Number of Spans 

      For testing continuous spans, the test specimen should incorporate no fewer than five spans; i.e., two end and three intermediate spans. End spans should be the span of internal spans.  Tests using four spans (two end spans and two internal spans) or three equal spans may be validated by comparing results against a five-span test of the same sample and adjusting the resultant load tables accordingly.