Adhesive Layer Modeling in Concrete Beam Strengthened with FRP in an EFG Framework

Abstract

The main challenging issue in concrete beam strengthening with FRP plates is the insurance of their joint performance. As been reported, the external load is mainly the primary reason for plate separation. The applied force corresponding to the moment of failure is called the debonding load. This load is of great importance. Besides, the determination of shear stress in the adhesive layer and tensile strain of the FRP plate is of the topics raised in empirical research. This study recommends using numerical methods to avoid the high cost of empirical studies. Here, failure concepts of the cohesive element are utilized. Horizontal and vertical springs are used to represent the properties of this element in which springs’ stiffness deputizes cohesive element characteristics and can be adjusted in three linear, nonlinear, and zero-stiffness steps. Springs’ stiffness is related to point displacements. So in an element-free Galerkin (EFG) method formulation, a set of springs, beam, and FRP is used to determine these displacements. Using these estimated nodes’ displacement values and utilizing springs’ stiffness, the unknown parameters inclouded debonding load, glue shear stress, and the tensile strain produced in the FRP plate can be determined. Whole calculations are coded in Matlab software. The results have been compared with the experimental outcomes of Kim and her colleagues’ work. These results indicate glue performance can be investigated through spring modeling based on the cohesive element in an EFG framework with adequate accuracy. So, the significant parts of an experimental setup can be avoided.