InterfacialdebondingmechanismofFRP-strengthenedconcretestructureswithBEM

In this paper, simulations of crack propagation of concrete and debonding of FRP-concrete in- terface in FRP-strengthened concrete structures are carried out by means of fully symmetric Galerkin multi- zone boundary element method. Cracks in concrete are considered as cohesive cracks (mode I), and the path of crack growth is priori unknown. Cracks on concrete-FRP interface are considered as cohesive shear cracks (mode II). The algorithm is given. From the numerical results, this method can deal with interfacial crack debonding and multi-crack propagation conveniently and effectively, and it is more precise than FEM. For FRP-strengthened three-point bending concrete beams, generation and propagation of diagonal crack in con- crete and interfacial crack caused by diagonal crack on FRP-concrete interface is also simulated. Numerical results shows that bond quality of adhesive and stiffness of FRP sheets are very important to the strengthening effect. 1 INSTRUCTIONS forcement of crack propagation, advantages of GMZBEM are obvious in this field. Boundary element method (BEM) is suitable for Fiber reinforced plastic (FRP) sheets/plates, espe- analyzing crack growth because discretization is cially carbon FRP (CFRP) sheets, are more and more made only on the zone boundary for elasticity, trac- widely applied in strengthened concrete structures tion on the boundary can be directly calculated, and (Wu 1997). Considerable research has been directed meshes are easily created (Aliabadi 1997), especially to investigate the application of FRP as external re- for those crack path is priori unknown. For cracks in inforcement primarily for strengthening the concrete concrete-like quasi-brittle material, the region of structures. The loading carrying capacities and duc- non-elasticity can be simplified into the cohesive tility can be enhanced with externally bonded FRP crack face because the region is very narrow. Hence, sheets.