Towards progressive debonding in composite RC beams subjected to thermo-mechanical bending with boundary constraints – A new analytical solution

Abstract

Interfacial debonding is a critical problem in beams strengthened externally by sticking a plate at its soffit. This is mainly due to uncertainty of failure mode when the beam is subjected to bending and boundary constraints. Many analytical solutions are available for pure-shear tests when beams are subjected to thermo-mechanical loads; however, only few studies are available when plated beams are subjected to bending. This paper presents a simple approach to study the combined effects of temperature dependent parameters and thermo-mechanical loads on debonding mechanism, interfacial stress-distribution, development of bond-length and load of debonding. First-order closed-form solutions are proposed to address two possible cases of simply supported beam: roller-ended or pin-ended. Proposed solutions also introduce temperature effects (as thermal strains) within the interfacial adhesive to fill the gap in literature; this is useful to relate the effect of glass-transition point of adhesive with the composite action. The analytical observations are validated with focussed experiments and literature, and verified with continuum-discrete FE model; leading to parametric investigations and key observations. Effects of temperature are defined in terms of reverse- and inverse-actions.