Guo Yongchang

The Influence of Hollow Imperfections of Adhesive on Performances of Interface of RC Beams Strengthened with HFRP

The mechanical characteristics of the interface with hollow imperfections for reinforced concrete (RC) beams strengthened with Carbon‐Glass fiber sheet is discussed, which is a new hybrid strengthening method. By establishing the constitutive equations of different materials, three interfacial models including imperfection dimension, imperfection location and imperfection amount are simulated using nonlinear finite element method. The shear stress and normal stress of glue layer, the first principal stress of concrete at the end of the interface and the stress distributions of different strengthening modes are analyzed. The results show that the shear stress of glue layer is sensitive for imperfection dimension and significantly increases with the imperfection dimension. However, the first principal stress of the concrete at the end of the interface marginally decreases with the imperfection dimension.

Energy Release Rate of Interface Crack in Rc Beams Strengthened with Fiber Reinforced Polymer under Four Point Bending

A popular method for strengthening reinforced concrete (RC) beams is to bond fiber reinforced polymer (FRP) plates to the soffit. An important failure mode for such retrofitted members is debonding of the FRP plates from the member due to high interfacial stresses near the intermediate crack. Accurate prediction of the energy release rate of interface crack between FRP and concrete is a prerequisite for designing against debonding failure. In this paper, a theoretical analysis was conducted to investigate the energy release rate of interface crack embedded in the FRP-plated RC beam subjected to four point bending. A mechanical analysis model including the consideration of the major flexural crack and tension steel reinforcement was established for the interface crack tip of plated RC beam. The deflection of the FRP-plated RC beam and the axial force in the plates were analyzed on the basis of the classical beam theory. The compliance of plated RC beam was derived before the tension steel yielding, and a theoretical solution of the energy release rate was then proposed. Moreover, numerical results based on the proposed theoretical model were presented to illustrate the effects of various parameters on the energy release rate of interface crack in the plated RC beam.

Analysis of Interface Properties of Hybrid Pre‐stressed Strengthening RC Beams with Crack

A finite element (FE) analysis model of interface layer is established for the pre‐stressed CFS‐GFS hybrid strengthened beams. An elastic solution for the interfacial stress in the adhesive layer of the retrofitted beams is developed as well. The analytical results were compared with the FE results of interfacial stresses in the beams with different thickness of the adhesive and the fibre sheet. Different heights of Cracks in the interfacial layer of the concrete beam are considered in FE Model. Analysis results show the strengthening pattern is of excellent interface performance and the strength of the fiber sheet can be effectively utilized. The results also indicate the shear and normal stresses in the interfacial layer of the concrete beam release at the locations of the cracks and reach the maximal value before the concrete cracked. The shear and normal stresses in the adhesive layer increase abruptly, and the cracks in the adhesive layer then appear. The axial stresses of hybrid fiber sheet near the...