Piezoelectric Control of Edge Debonding in Beams Strengthened with Composite Materials: Part I – Analytical Modeling

The use of piezoelectric materials for the control of the edge stresses and the edge debonding failure in reinforced concrete beams strengthened with externally bonded composite materials is analytically investigated. A mathematical model that incorporates layers of piezoelectric active materials embedded or surfacemounted on the composite strengthening strip is developed. The model is derived using the electromechanical analog for the variational principle of virtual work along with the compatibility conditions, the piezoelectric constitutive laws, and the closed form solutions for the stresses and displacements in the adhesive. The response of a full-scale strengthened beam to mechanical loads and to different schemes of piezoelectric actuation is investigated in terms of the localized stresses near the edge of the bonded composite strip. The results show that in spite of their limited size and actuation capabilities, the piezoelectric actuators can induce shear and vertical normal stresses that are of similar magnitude but opposite sign to the stresses induced by the mechanical load. Thus, it contributes to the prevention of the debonding failure that characterizes the response of the strengthened beam. The original contribution of the study is in addressing the challenge of using piezoelectric smart and active materials in full-scale civil engineering structures, in developing the methodologies and the tools for the quantitative evaluation of the response of such advanced structural member, and in presenting a potential solution to the edge-debonding problem.