| General bi-material interface fracture mechanics theories and experimental models are reviewed,among which: rigid joint model,semi rigid model and flexible joint model based on different beam theories are introduced in detail.Crack tip stress field and deformation field of these three joint models are calculated and compared to the results of FE method.Further a combined analytical and experimental approach is presented to evaluate mode-II dominated loading fracture of glass fiber reinforced plastic(GFRP)-concrete bonded interfaces under four-point bending load,and closed-form solution of fracture toughness of the specimens is provided.When modeling the fracture process,first order shear deformation beam theory is adopted for considering the influence of transverse shear deformation in each sub-layer,and the effect of interface crack tip deformation on the energy release rate is taken into account.The concrete sub-layer is reinforced by using rebars for the reason of its fragileness under tension and shear,and the rhythmicity of testing results is improved as well.By comparing with the FE simulation,the proposed method is verified to be an efficient way for measuring the fracture toughness of mode-II dominated loading GFRP-concrete interface.The improved solution of fracture toughness can be used to effectively evaluate the interface performance and predict the critical load of interface fracture of composite reinforced concrete structure. |
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