Abstract: The shear behavior of self-compacting concrete beams with hybrid steel fiber (SF)-polyvinyl alcohol (PVA) fiber was studied through tests with different volumetric dosages of the SF-PVA hybrid fiber,different hybrid ratios of the two fibers,and varied spacing of stirrups.Test results manifested that adding SF or PVA fiber into concrete beams could effectively restrain the generation and propagation of cracks and improve the shear capacity of beams.The specimen with stirrup spacing of 150 mm,volumetric dosage of 1% and hybrid ratio of 1∶1 has the maximum cracking load and shear capacity.Under the same volumetric content and hybrid ratio,reducing the stirrup spacing could remarkably reduce the ultimate load value of the beam,but has little effect on the crack load value of the beam.In addition,a BP neural network model for strength prediction was established with SF's volumetric content,PVA fiber's volumetric content,and stirrup spacing as input layer and ultimate shear as output layer.Ultimate shear force was fitted and the prediction result was accurate.

Key words: self-compacting concrete beam, SF, PVA, hybrid ratio, shear bearing capacity, BP neural network