Shear performances of reinforced ultra-high performance concrete short beams

This study aims to understand the shear performance of reinforced ultra-high performance concrete (R-UHPC) short beams and to propose a calculation method for their shear capacity. A total of 11 R-UHPC short beam specimens were tested to investigate the effects of key parameters on the shear capacity, including steel fiber volume fraction, longitudinal reinforcement ratio, stirrup ratio, and shear span-to-depth ratio. Experimental results indicated that the shear capacity increased with the increase of steel fiber volume fraction, longitudinal reinforcement ratio, and stirrup ratio, while it decreased with the increase of shear span-to-depth ratio. Results also showed that for R-UHPC beams, the effect of shear span-to-depth ratio can only be ignored for a ratio less than 1.2 rather than 1.5 that is required for reinforced concrete (RC) beams by the Chinese design code. Moreover, it was found that the calculation methods for the shear capacity of R-UHPC beams in the current codes underestimated the shear capacity of the specimens by 30 % similar to 50 %, as these methods did not consider the aforementioned significant parameters. A calculation method was proposed based on the modified compression field theory (MCFT) to comprehensively consider all the aforementioned parameters. The proposed method exhibited a higher accuracy and less dispersion as compared to the methods specified by current codes.