Model to simulate the behaviour of RC beams shear strengthened with ETS bars

Abstract

To predict correctly the deformational and the cracking behavior of reinforced concrete elements failing in shear using a smeared crack approach, the strategy adopted to simulate the crack shear stress transfer is crucial. For this purpose, several strategies for modeling the fracture mode II were implemented in a smeared crack model already existing in the FEM-based computer program, FEMIX. Special development was given to a softening shear stress-shear strain diagram adopted for modeling the crack shear stress transfer. The predictive performance of the implemented constitutive model was assessed by simulating up to failure a series of eight beams tested to appraise the effectiveness of a new strengthening technique to increase the shear resistance of reinforced concrete beams. According to this strengthening technique, designated as Embedded Through-Section (ETS), holes are opened through the beam’s section, with the desired inclinations, and bars are introduced into these holes and bonded to the concrete substrate with adhesive materials. The strengthening elements are composed of steel bars bonded to the surrounding concrete with an epoxy adhesive. By using the properties obtained from the experimental programs for the characterization of the relevant properties of the intervening materials, and deriving from inverse analysis the data for the crack shear softening diagram, the simulations carried out have fitted with high accuracy the deformational and cracking behavior of the tested beams, as well as the strain fields in the reinforcements. The constitutive model is briefly described, and the simulations are presented and analyzed.