Higher-Order Frame Model for Nonlinear Analysis of RC Beams Strengthened in Flexure with Externally Bonded Plates

Abstract

Many existing reinforced concrete (RC) structures very often do not satisfy building codes used nowadays to design both buildings and infrastructures because they either deteriorated due to environmental attacks (e.g. chloride induced deterioration) or because they were originally designed according to old and inadeqyate criteria. Retrofitting and/or strengthening are necessary in order to increase the safety level of the structure existing structure. A recent methodology to enhance the flexural strength of RC beams uses FRP plates or sheets glued to the tension side of the beam. A commonly observed failure mode for the beams strengthened in flexure with externally bonded plate is the one associated with debonding of the strengthening plates at lower loading levels than the theoretical values. Consequently, the inclusion of the plate-debonding failure into the analytical model is necessary in developing the reliable numerical tool. This paper presents a higher-order displacement-based frame element with covercrete-interface. The covercrete-interface slip between the beam and in the strengthening plate. The proposed model is employed to confirm and investigate premature failure modes observed in experimental tests.