Dual potential capacity model for short and deep reinforced concrete members containing steel fibers

Abstract This study presents an analytical model for estimating the shear strength of short and deep steel fiber‐reinforced concrete (SFRC) members with a shear span‐to‐depth ratio less than 2.5. To this end, a dual potential capacity model (DPCM) is developed based on the demand‐capacity approach for evaluating the shear strength of SFRC beams that fail in shear. In this model, the total shear demand is divided into uncracked compression and cracked tension zones, and corresponding potential capacity curves are formulated for each zone. The shear demand in the cracked tension zone is calculated based on force equilibrium between global and local stress fields, while the remaining shear demand is assumed to be resisted by the compression zone. Additionally, the effect of vertical clamping pressure within the short shear span is incorporated into the potential shear strength of the uncracked compression zone. The shear contribution of steel fibers is also considered by employing the direct tension force transfer model (DTFTM), which accounts for the randomly oriented steel fibers in three‐dimensional space and their pull‐out failure. To validate the proposed approach, a total of 245 shear test results for short and deep SFRC members were collected from the literature. The predictive results demonstrate that the shear strengths of SFRC specimens can be estimated with a high degree of accuracy using the proposed DPCM, compared to the estimates obtained from the code equations in ACI 318 and ACI 544.4R.