Punching shear capacity of fiber-reinforced concrete suspended slabs: Database analysis and models assessments

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The punching shear capacity is critical in the design of suspended slabs. Fiber reinforcement has been introduced to improve the punching shear capacity of these slabs. Several models have been used to predict the punching shear capacity of fiber-reinforced concrete slabs (FRCS). Some of these models accounted only for the contribution of concrete (e.g., ACI 318–19 and CSA-19), while others also accounted for the contribution of reinforcing steel (e.g., JSCE-07 and Eurocode-2 and/or fibers (e.g., fib MC-10). In the present study, experimental results from 240 FRCS and 78 control slabs (without fibers) were collected and analyzed to assess the effect of various parameters and the extent to which these parameters affect the predicted punching shear capacities by various models. Four main parameters, concrete compressive strength, steel reinforcement ratio, fiber reinforcement, and punching shear perimeter, were considered in the assessment of various design and theoretical models. The study revealed that most design-based models underestimate, to varying degrees, the punching shear capacities with large variability. To better capture the dependence of the punching shear capacity on the four main parameters, a new model was proposed for FRCS. The proposed model considers the critical shear perimeter at a distance d from the face of the column and accounts for the fiber contribution as a function of the residual strength parameter obtained from standard beam tests (ASTM C1609). Predictions of the proposed model were characterized by high accuracy and low coefficient of variation (CV).