The shear design equation of CSA S806-02 does not consider the effect of the axial stiffness of the reinforcing bars for beams with effective depth greater than 300 mm. This paper examines the shear strength of such beams without stirrups. A total of 16 beams reinforced with GFRP, CFRP, and steel bars were tested under four-point monotonic loading. The test results were analyzed and compared with the predictions of CSA S806-02 shear design equation. It was observed that the conservatism of CSA S806-02 prediction, for beams with effective depth greater than 300 mm, increased with the increase in the axial stiffness of the reinforcing bars. Based on the test results, a modification to the CSA S806-02 shear design equation is proposed. The proposed modification was found to be consistent for predicting the shear strength of beams with different axial stiffness of the reinforcing bars.
This paper presents experimental work to investigate the strength and cracking characteristics of optimised self-consolidating and vibrated rubberised concrete mixtures with/without steel fibres (SFs) using large-scale reinforced concrete beams. The test beams were cast with varying percentages of crumb rubber (CR) (0 to 35%), SF volume fractions (0, 0·35 and 1%) and SF lengths (35 and 60 mm). The performance of some design codes and published empirical equations was evaluated in predicting the shear capacity and first cracking moment of the tested beams. The results showed that the inclusion of SFs could alleviate the reduction in the shear capacity and first cracking moment that resulted from the addition of CR. In addition, combining CR and SFs contributed to developing sustainable concrete beams with high deformability, reduced self-weight and improved shear capacity. The composite effect of CR and SFs also helped to narrow the developed cracks and change the failure mode from brittle shear failure into ductile flexural failure, particularly for the SF volume of 1% (35 mm length). Comparisons of the predicted and experimental results indicate that most of the proposed equations can satisfactorily estimate the shear strength, but overestimate the first cracking moment.
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