Dynamic geometrically nonlinear behavior of FRP-strengthened walls with debonded regions

This paper studies the dynamic geometrically nonlinear behavior of walls that are strengthened with fiber-reinforced polymer (FRP) composite materials but include preexisting debonded regions. For that purpose, two specially tailored finite elements corresponding to the perfectly bonded regions and debonded regions within the layered wall are formulated under the umbrella of a dynamic analysis. The two finite elements are based on a high-order multilayered plate theory. The geometrical nonlinearity is introduced by means of the Von Karman nonlinear strains. The convergence and validity of the geometrically nonlinear dynamic model are studied for the case of a locally debonded FRP-strengthened wall under in-plane shear loads applied at a constant rate. The unified model of the strengthened wall with a local delamination is then used for studying the dynamic nonlinear behavior under different levels of shear loading rate. The dynamic results and the comparison with static analyses reveal the impact of the geometrical nonlinearity on the dynamic behavior of the debonded composite layer and the evolution of interfacial stresses at its perimeter. At the same time, they reveal the impact of the dynamic effects on the geometrical nonlinearity and critical points it involves.