An improved strut-and-tie model to predict the ultimate strength of steel fiber-reinforced concrete corbels

In this paper, a strut-and-tie model is proposed for predicting the ultimate shear capacity of steel fiber reinforced concrete corbels. The proposed strut-and-tie model accounts for the effect of concrete strength, fiber volume, fiber aspect ratio, ratio of main steel and horizontal stirrups ratio, horizontal load ratio and shear span-to-depth ratio. The ultimate shear predictions of the proposed model are validated with 146 test results from the literature. The comparison shows that the proposed model performs well in predicting the ultimate shear capacity of steel fiber reinforced concrete corbels. The overall average value of the ratio between the experimental and the predicted strengths is 1.1 and the standard deviation is 0.105. Compared with the existing testing results, the strut-and-tie model predictions of the American and the British standard are more conservative than the improved strut-and-tie model. Also, comparative studies between the proposed model and the strut-and-tie models provided by other researchers in the literature are presented. Finally, sensitivity studies are performed for fiber parameters. The ratio between the ultimate shear strength for steel fiber reinforced concrete corbels and the ultimate shear strength for non-fibrous corbels are studied versus the steel fiber parameters considering shape of fiber and shear span-to-depth ratio. The studied fiber parameters are fiber volume content and fiber aspect ratio.