3. Fibre Reinforced Polymer Composites Two-Way Slabs

This chapter presents a modular assembly of sandwich structures using glass fibre reinforced polymer (GFRP) components for two-way slab applications. The sandwich assemblies were built-up sections made from pultruded web-core box (i.e. square hollow section) profiles incorporated between two flat panels, connected via adhesive bonding or novel blind bolts. Two different pultrusion orientations were achieved and examined i.e. flat panels with pultrusion directions either parallel (unidirectional orientation) or perpendicular (bidirectional orientation) to the web-core box profiles. The effects of pultrusion orientation, shear connection and the presence of foam core materials on strength and stiffness were investigated by experimental testing of two-way slab specimens until failure. Sandwich slabs with unidirectional orientation showed premature cracking of the upper panel between fibres, whereas those with bidirectional orientation showed local out-of-plane buckling of the upper flat panel. The unidirectional slab also showed greater bending stiffness than bidirectional slabs due to the weak in-plane shear stiffness provided by the web-core profiles, which introduced partial composite action between the upper and lower flat panels of the bidirectional slab. Finite element models and analytical techniques were developed to estimate deformation, failure loads and the degree of composite action, and these showed reasonable agreement with the experimental results.