Abstract
Abstract Some normative recommendations are conservative in relation to the shear strength of reinforced concrete beams, not directly considering the longitudinal reinforcement rate. An experimental program containing 8 beams of (100 x 250) mm2 and a length of 1,200 mm was carried out. The concrete compression strength was 20 MPa with and without 1.00% of steel fiber addition, without stirrups and varying the longitudinal reinforcement ratio. Comparisons between experimental failure loads and main design codes estimates were assessed. The results showed that the increase of the longitudinal reinforcement ratio from 0.87% to 2.14% in beams without steel fiber led to an improvement of 59% in shear strength caused by the dowel effect, while the corresponding improvement was of only 22% in fibered concrete beams. A maximum gain of 109% in shear strength was observed with the addition of 1% of steel fibers comparing beams with the same longitudinal reinforcement ratio (1.2%). A significant amount of shear strength was provided by the inclusion of the steel fibers and allowed controlling the propagation of cracks by the effect of stress transfer bridges, transforming the brittle shear mechanism into a ductile flexural one. From this, it is clear the shear benefit of the steel fiber addition when associated to the longitudinal reinforcement and optimal values for this relationship would improve results.
Highlights
Reinforced concrete (RC) is widely used in several structures around the world
As far as the use of new materials is concerned, the use of steel fiber reinforced concrete (SFRC) has been increasingly used in structures around the world due to its various structural capacity benefits, which according to Yakoub [2], Amin and Foster [3], Nzambi et al [1] are the increase in shear strength, tensile strength, flexure and ductility
Experimental results are presented here considering SFRC beams without stirrups tested to failure, varying the reinforcement ratio, intending to assess the SFRC beams behavior under shear forces
Summary
Reinforced concrete (RC) is widely used in several structures around the world. Owing to environmental issues in the steel production chain and its associated high costs, several alternatives and technically viable solutions have been proposed in civil construction applications worldwide, such as the use of new composite materials in structural reinforcement, the production chain of which is ecologically friendly using less expensive and more environmentally friendly manufacturing techniques [1]. As far as the use of new materials is concerned, the use of steel fiber reinforced concrete (SFRC) has been increasingly used in structures around the world due to its various structural capacity benefits, which according to Yakoub [2], Amin and Foster [3], Nzambi et al [1] are the increase in shear strength, tensile strength, flexure and ductility. Several studies have been developed with SFRC beams without stirrup reinforcement [5], [6], with the objectives of determining the main variables that control the shear behavior Among these variables are the influence of steel fiber with different longitudinal reinforcement rates, Yavas and Goker [7] and the variation of the fiber volume, Resende et al [8]. According to Yakoub [2] increasing the steel fibers content may generate an increase in the shear strength and improve the beam ductility
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