Colorcoat Connection® FAQ’s – Structural performance tests
You have recently talked about the structural performance of built-up cladding systems. What kind of tests were carried out in order to collate the findings here?
A programme of tests was undertaken at a NAMAS accredited laboratory No. 0312 to determine the performance characteristics of typical built-up cladding systems and to verify their structural adequacy.
There were three categories of test: In plane tests:In-plane ‘pull’ tests were carried out to determine the in-plane stiffness of a typical built-up cladding system and the contribution of the liner and external sheets to the overall stiffness of the assembly. Tests were conducted with and without the external sheet and compared to the base case of purlin and spacer alone.
Uplift tests:In the uplift condition, the cladding is required to resist lateral-torsional buckling of the purlin by preventing the purlin from twisting. In theory, the cladding is able to do this due to its flexural stiffness, but this has been brought into question recently as the cladding depth has increased. In particular, with a space of 180mm or more between the internal and external sheets, can the two sheets be considered to act compositely together or should designers assume that the liner is acting alone? The purpose of the uplift test was to answer this question and to determine whether sufficient restraint is provided to permit the purlin to support the required load. This configuration simulates the up-lift from wind and pressure differentials which are often the limiting load case for roofs.
Gravity load tests:One of the primary concerns regarding the use of ever deeper built-up cladding systems is the ability of the cladding assembly to support the down slope component of the gravity loading without sagging excessively. While the in-plane tests provided good numerical data regarding the down slope behaviour of the cladding assembly, full scale tests were needed to study the overall performance of the system under gravity loads.
For more information on the above, visit http://www.colorcoat-online.com/en/products/seminars_&_papers/papers/ or contact the Colorcoat Connection® helpline on +44 (0) 1244 892434