Experimental and numerical analysis of advanced cementitious composites for sustainable roof elements

The use of Ultra High Performance Fibre Reinforced Composites (UHPFRC) allows the designer to reduce the dead weight of roofing keeping concrete covering structures still more competitive in relation to steel structures in terms of costs, thermal and acoustic insulation and fire resistance. Thin plates can be used as tertiary elements in roof floors beside the border beams and the simply supported prestressed precast roof elements. The high performances of the 2m wide elements are mainly used for bending along the 2,5m span and in order to drastically simplify the detailing of the support regions. The sandwich technology potential is maximized by coupling the exceptional mechanical characteristics of Textile Reinforced Mortars (TRM) and UHPFRC with the insulation capability of a polystyrene layer. It is expected that the coupling of a low stiffness material with concrete layers brittle at the specific level, could give back a composite panel characterized by multi-cracking phenomena and high inertia. Due to the internal actions acting on the horizontal bearing component, the insulating core should ensure an adequate shear transfer, able to keep the TRM layer mainly in tension and the FRC plate mainly in compression. This configuration makes lighter structures possible because it fully exploits the material used and, secondly, makes them more environmental friendly because recycled materials can be used. In this paper, the attention will be focused on the problems inherent with the experimental evaluation of individual materials constitutive relations and on the non-linear finite elements modelling of the bending behaviour of the composite.