Composite Roofing of PIR Sandwich Panels: Numerical and Experimental Approach

Abstract

The PIR panels are composite elements made of an inner core of poly-iso-cyanurate (PIR) solid foam injected between two external sheets of fabric or polypropylene. When testing composite samples having such structure the obtained results (in terms of compression and bending resistances) usually reach relatively high levels. This suggests a possible use of panels in applications under distributed loading and not only as simple thermos-insulating layers. A large range of applications thus derives, i.e. cladding of timber roofing, sloping support for hydro-insulation in flat concrete roofs, or hydro-insulation support for trapezoidal sheeting for flat or even curved roofs. The paper presents an experimental and numerical study on two practical cases, i.e. flat concrete roofs and trapezoidal sheets roofs respectively. Standard testing of samples, taken from the composite core and from the membrane, have been performed in the frame of present investigation together with testing of some composite samples in compression and bending. Typical roof loading as gravity (dead + snow) load or wind suction have been analysed in the numerical simulation (reproducing the test arrangement) in order to assess panel response and to evaluate the practical applicability of these composites. Conclusions on stress distribution and deflections both under gravity and uplift load are presented. The high resistance of PIR composite panels (well beyond design loads calculated by the code) is confirmed, clearly indicating their practical applicability in the cases under study. This also meets the producer requirements who intends to obtain in the future an official agreement allowing to supply these particular composite solutions using PIR on the market.