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

Abstract

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.

Impact of thermal loads on interfacial debonding in FRP strengthened beams

“…The amplification of the interfacial stresses raises the question of the impact of the thermal loads on the debonding failure of the beam. This question, which was not addressed in Rabinovitch (2007a), stands in the focus of the present paper.…”

“…The first one is a stress analysis model that takes the effects of the mechanical and the thermal loads into account. The model follows Rabinovitch (2007a), Frostig (1997), Rabinovitch and Frostig (2000) but takes into account the effect of the temperature on the elastic properties of the adhesive (also see Frostig andThomsen, 2007, 2008b). For completeness, the relevant parts are outlined in Section 2.1.…”

“…These stresses tend to concentrate near irregular points such as cracks, debonded regions, or edges. For example, Rabinovitch (2007a) showed that service thermal loads significantly amplify the stress concentration near the edge of the FRP strip. The amplification of the interfacial stresses raises the question of the impact of the thermal loads on the debonding failure of the beam.…”

“…The model and debonding simulation presented in Rabinovitch (2008a) is, however, limited to a single loading system with the advantage of linear and quadratic dependency of the displacements and the energy, respectively, on a single load factor. The procedure does not apply to a combined mechanical and thermal loading or to other combinations of loading systems (see, for example, Rabinovitch, 2007b,c for the assessment of the ERR under combined mechanical and electrical loads of a piezoelectric structure).…”

Survey of Active Structural Control and Repair Using Piezoelectric Patches

“…An analytical model of piezoelectric control was proposed in the work of Rabinovitch [64]. The model was presented in the context of beams that are strengthened by composite materials and developed for the control of edge debonding in the respective beams.…”