Modeling of inexpensive strengthening technique for reinforced concrete beams

Abstract

A noble cause motivated the interest to carry out research work on an inexpensive strengthening technique using ferrocement for reinforced concrete beams applicable in developing countries. Ferrocement as an inexpensive strengthening material is suitable for some developing countries where using such a technique offers an optimum strengthening solution for deteriorated structures. The main experimental component of this research work on strengthening reinforced concrete beams has been already published. This paper primarily presents material characterization and finite element models to study the flexural and interfacial types of behavior of ferrocement-strengthened concrete beams. Twenty-seven (27) ferrocement specimens were tested under direct tension to characterize the behavior of the used ferrocement. Special grip attachments have been designed and manufactured to elude local failure at the specimens� ends. Based on the direct tension test results, a stress-strain relationship has been developed to describe the uniaxial tensile constitutive relation for ferrocement in the finite element models. The interfacial bond behavior between the ferrocement and the concrete is considered in the models by using interface elements. Moreover, a user-defined subroutine for the microplane constitutive law is integrated into the model for the concrete material. Results of the finite element modeling are presented for the ultimate load-carrying capacities, load-deflection history, and stress distributions at the ferrocement/concrete interface. The finite element modeling results have been validated against the published experimental findings and have shown reasonable agreement.