Test results on concrete-filled GFRP hollow profiles subjected to axial load

The interaction between the useful material for construction as concrete and the innovative material, as fiber reinforced polymer (FRP), represents by now a very interesting application in engineering structural field. In fact this topic involves the constitutive law for every material considered, the type of bond between two different materials and, finally, the structural behaviour of hybrid material (Concrete + FRP) at ultimate limit state. In the field of strengthening of concrete structure the benefits that can be derived from employment of composite material are by now verified especially in presence of FRP strip and lamina.
Also in presence of the composite pultruded profiles the literature shows many results for structural elements (columns and beams) that are made with hollow GFRP pultruded profiles filled with concrete, but in this case the experimental investigation needs more study.
In fact the structural behaviour of this type of column has been already analysed in relation to the evaluation of the slenderness value, the influence of bond in the phase of collapse, and for the analytical model’s view point. This research shows a global comparison on type of collapse in presence of square and circular cross section to analyse the weakness behaviour.
The tests were carry out on GFRP-concrete columns with axial load applied to all transversal section. It is important to mark that a better behaviour of profiles, for this tests, is given by filament winding GFRP profiles and not with pultruded profiles.