Dynamic debonding in concrete beams strengthened with composite materials

The brittle and unstable debonding failure in concrete beams strengthened with externally bonded composite materials is dynamic by nature. This paper studies the dynamics of the debonding process in the externally strengthened beam. The paper adopts an analytical approach and presents a high order model that combines the dynamic response with the consideration of the interfacial debonding process. The latter aspect is introduced using a coupled cohesive interface formulation that is implemented in the dynamic model of the layered beam. The study focuses on the role of the dynamics in the debonding behavior and highlights two sides of this interaction. The first one is the impact of the debonding process on the evolution of a dynamic response. The second one is the impact of the dynamic structural response on the initiation, growth, duration, and stability of the debonding process. The two aspects are highlighted through a numerical study of a cracked beam strengthened with a composite layer. The numerical study quantifies the dynamic debonding process in terms of the variation of the load, displacements, stress resultants, stresses in the adhesive layer, and interfacial tractions across the cohesive interface in time. It also monitors the movement and the velocity of the debonding front during the failure process. Finally, it examines the impact of the loading rate on the dynamic interfacial process. Concluding remarks regarding the role of the dynamic effects in the debonding mechanism and its impact on the strengthened beam close the paper. (c) 2012 Elsevier Ltd. All rights reserved.