Study the Flexural Behaviour of Pre-Cracked Frp Beams Under Three-Point Bending

Abstract

In this study, numerical analysis is performed on pultruded glass fibre reinforced polymer beams to access the flexural response of strengthened pre-cracked beams. Material constitutive relations, damage failure criterion is used in ABAQUS tools with the help of USDFLD user-subroutine. Flexural behaviour of pre-cracked beams with and without stiffening elements are studied and compared with the published experimental data. Stiffening elements such as CFRP laminates and GFRP web-stiffeners are used to strengthen the pre-cracked beams. Variation of crack lengths with different Length-to-depth (L/d) ratios of beams are the parameters considered in this study. Load-displacement behaviour, propagation of cracks and failure load of pre-cracked FRP beams have been studied and compared with the results available in literature. Firstly, unstrengthen beams with crack location at different zones of web-flange junction was analysed and it was found that load bearing capacity of section was reduced. On the other hand, pre-cracked beams of L/d ratio of 11 strengthened with web stiffeners and CFRP laminates showed 40-50% more load carrying capacity and stiffness compared to beams strengthened only with CFRP laminates. This behaviour was also observed in beams of L/d ratio 7 with 20-25% increase in load carrying capacity. For smaller L/d ratio of 3, web crushing was observed. Also, for smaller L/d ratio of 3 no major difference in load-displacement curves was observed in beams strengthened with and without stiffeners.