Transfer of impulsive loading on cladding panels to the fixing assemblies

The fixing assemblies for prefabricated cladding panels on buildings, are o ften designed on an empirical basis, to support the dead weight of the pane l, wind loads and possibly temporary loads arising during construction. If, subsequently. the design loads are accidentally exceeded but the panel is undamaged; it may be necessary to check the condition of the fixings. A phy sical check would require costly dismantling and reconstruction of the pane l but, as an alternative, this paper presents an analysis of the force tran sferred to cladding fixing assemblies when the panel is subjected to impuls ive loading, using the finite element analysis program, DYNA3D. The results were validated with experimental results from impact tests on a steel plat e supported on four steel bars. Having obtained this validation, a finite e lement analysis was then carried out to determine the response or fixings f or panels under different levels of blast loading using two different model s for the panel-fixing assemblies. The first model considers only the effec t of out-of-plane fixing, whilst in the second model both the out-of-plane fixings and in-plane fixings are considered. It was observed that forces tr ansferred to fixings include an axial force, shear forces, and bending mome nts and these force components can vary along the length of the fixing. Ins pections of cladding panels, after being subjected to impulsive loads, ofte n show that the connection between the fixing and the panel and between the fixing and the support structure are more vulnerable to impulsive loading than the panel itself, The FE analysis has shown that forces in the fixings are related to the dynamic response of the cladding panel; hence damage to the fixings could be deduced from damage to the panel. (C) 2001 Elsevier S cience Ltd. All rights reserved.