Hugo C. Biscaia

Externally bonded fiber-reinforced polymer (FRP) composites have been widely used for the strengthening and repairing of reinforced concrete (RC) beams. Existing studies have denstrated that the full-range behavior and the associated debonding mechanism of the FRP-to-concrete interface between two adjacent cracks in the FRP-plated RC beam are different from those of the pull-off bonded joint. Moreover, the bond behavior between the FRP and the concrete may be affected by interfacial thermal stresses induced by the service temperature variations (i.e., the thermal loadings). Based on a fully reversible bilinear bond-slip model, this paper presents an analytical study to investigate the full-range deformation behavior of the FRP-to-concrete interface between two adjacent cracks under combined mechanical and thermal loadings. The analytical results have indicated that the thermal loadings may significantly influence the full-range deformation behavior and the axial stress distribution of the FRP plate, although the material properties of concrete, adhesive, and FRP are assumed to be not affected by the service temperature variations. A temperature increase leads to an increase in the ultimate load of the bond interface and vice versa. A finite element (FE) model with different considerations of the bondline damage is developed to verify the proposed analytical solution. The reliability of the proposed analytical solution is then validated by the comparisons between the analytical results and the corresponding predictions provided by the FE model. © 2022 Elsevier Ltd

Concrete structures Externally Bonded Reinforced (EBR) with Fibre Reinforced Polymers (FRP) have been studied and used since the end of the last century. However, several issues need to be better studied in order to improve performance. The influence of size of anchorage plates used on Reinforced Concrete (RC) structures strengthened with EBR FRP composites, the external compressive stress to be applied on the anchorage plate and the numerical simulation of this region are some of the topics that need to be more carefully studied in order to clarify the performance of the FRP-to-concrete interface within the anchorage plate region. This study proposes a design methodology to estimate the amount of external compressive stress necessary to be applied on the anchorage plate of EBR systems with FRP composites, in order to avoid premature debonding. The external compressive stress imposed on the FRP composite is intended to simulate the effect produced by a mechanical anchorage system tightened to the EBR system. The results from the design proposal, when compared with the numerical ones, were efficient enough on the prediction of the bond strength improvement of FRP-to-concrete interfaces. © 2018 Elsevier Ltd

The monitoring of structures has undergone important advances with the improvements of digital cameras available on the market. Thus, the Digital Image Correlation (DIC) technique has become a viable way of studying engineering problems. Recently it has been used in the debonding failure process between the reinforcement and the substrate. The methods or methodologies that should be followed to obtain the results associated to the debonding phenomenon using the DIC technique need to be better understood and studies on this topic are scarce. The present work therefore proposes a new and inexpensive method to monitor the interfacial behaviour between a reinforcement material and a substrate by combining the use of the DIC technique and a simplified nonlinear bond-slip model. For the validation of the proposed method, a series of single-lap shear tests with a sufficient long bond length carried out by the authors are used. Based on the slip distribution obtained from the DIC technique, it was found that a third-degree polynomial function can be used to approximate the interfacial bond-slip curve of the joint. The validation of the model is made with several analytical solutions using the proposed bond-slip model. © 2018 Politechnika Wrocławska