Effect of fiber dosage and prestress level on shear behavior of hybrid GFRP-steel reinforced concrete I-shape beams without stirrups

Abstract

Corrosion of steel reinforcements embedded in concrete elements is generally known as one of the most common reasons that shorten the service life of the structures. The present study aims to contribute in overcoming this problem by replacing steel stirrups as shear reinforcement of concrete beams using a steel fiber reinforced self-compacting concrete (SFRSCC). In the present research the potential of SFRSCC for improving the shear resistance of the beams without stirrups is explored. In order to further reduce the risk of corrosion in this type of beams, a hybrid system of flexural reinforcement composed of a steel strand and GFRP rebars is applied and properly arranged in order to assure a relatively thick concrete cover for the steel reinforcement. The GFRP bars are placed with the minimum cover thickness for providing the maximum internal arm and, consequently, mobilizing efficiently their relatively high tensile strength. The effectiveness of applying different dosages of steel fibers and varying the prestress force to improve the shear behavior of the designed beam are evaluated. By considering the obtained experimental results, the predictive performance of a constitutive model (plastic-damage multidirectional fixed smeared crack model) implemented in a FEM-based computer program, as well as the one from three analytical formulations for estimating shear resistance of the developed beams were assessed. The FEM-based simulations have provided a good prediction of the deformational response and cracking behavior of the tested beams. All the analytical formulations demonstrated acceptable accuracy for design purposes, but the one proposed by CEB-FIP Modal Code 2010 predicts more conservative shear resistance.

An experimental study on the shear behaviour of reinforced concrete beams with macro-synthetic fibres

“…Research into shear has also been applied by some authors to fibre-reinforced concrete (FRC) structural elements, in which the most important variables were: amount [3], shape, material and slenderness (aspect ratio, l/d) of fibres [4,5], as well as the presence [6,7] or absence [8][9][10][11][12][13][14][15] of stirrups, or the combination of stirrups and fibres [7,16,17].…”

Assessment of different methods for characterization and simulation of post-cracking behavior of self-compacting steel fiber reinforced concrete

“…The reason is that the orientation of fibers in self-compacting SFRC slabs and shell type structures is mostly orthogonal to the flux lines and the fiber structure has predominantly a 2D profile orientation (Abrishambaf et al 2013). On the other hand, in prismatic elements, like the specimens produced for performing bending tests, the fibers are preferentially aligned along the longitudinal length of the element due to both the reorientation of the fibers due to the self-compacting concrete flow and the wall effects that occur during casting (Stähli 2008, Soltanzadeh et al 2016b, Mazaheripour et al 2016. This fiber alignment along the longitudinal axis of the prismatic elements, hence perpendicular to the fracture plane, leads to the overestimation of the postcracking residual strengths for two-dimensional elements such as slabs and shells.…”

Assessing the applicability of a smeared crack approach for simulating the behaviour of concrete beams flexurally reinforced with GFRP bars and failing in shear

“…Glass fiber reinforced polymer (GFRP) bars have been increasingly used as flexural reinforcement in concrete beams and slabs due, mainly, to their immunity to corrosion, high strength-to-weight ratio, and nonmagnetic nature [1][2][3][4][5][6]. However, when compared to steel bars applied in the reinforcement of concrete structures, GFRP bars have smaller elasticity modulus (E l ), bond performance and fatigue resistance [7][8][9], their mechanical properties are more detrimentally affected by high temperature (above their glass transition temperature, which is relatively small), [10][11][12], have more brittle behaviour (linear-elastic up to abrupt tensile rupture), and are more difficult of being deformed for ensuring proper anchorage conditions.…”