The structural behaviour of moulded gratings made of glass fibre reinforced plastics

Abstract

Moulded GFRP gratings provide several advantages over conventional metallic gratings and have steadily increased in popularity, even though their use within the building sector is often accompanied by costly approvals. Those are frequently required due to a lack of adequate design rules. To push the development of such rules, a comprehensive study on the load bearing behaviour of GFRP gratings is conducted and briefly presented herein.Two failure types, shear and bending failure, are identified in three-point bending tests and further studied by numerical analyses. Subroutines are developed and integrated into a commercial FE software to account for nonlinear material behaviour related to microdamage and macroscopic fracture. Thus, relevant stress and damage states at the scale of a lamina are clearly identified. Based on these investigations, a mutual interaction of bending and shear stresses on the load-bearing capacity can be excluded.Additional tests are carried out on full-size grating panels and recalculated with a structural frame analysis program. The research suggests that a warping restraint shall be assumed in the crossings between orthogonal bearing bars which significantly increases the effective torsional stiffness. It can also be shown that torsion-induced shear stresses do not contribute to the development of shear failure.