Material Variability and Quality Control Effects on Shear Resistance of RC Structures: A Reliability Sensitivity Study

The reliability of engineering structures is essential to ensure safety, durability, and sustainability. In reinforced concrete (RC), shear resistance is one of the most uncertain design aspects due to the natural variability of material properties and construction quality. Conventional design methods defined by Eurocode rely on characteristic values and partial safety factors that may not reflect the actual performance of in situ concrete. This study proposes a probabilistic framework for shear assessment that integrates material variability derived from conformity testing. Statistical parameters, including mean value and coefficients of variation (COV) of compressive strength, are incorporated into comparative reliability analysis using the First-Order Reliability Method (FORM) and Latin Hypercube Sampling (LHS). Parametric analyses are performed to quantify the influence of material variability on the reliability index β and failure probability Pf. The effect of varying the coefficient of variation (CoV) of the concrete compressive strength is investigated in the range from 0.01 to 0.2, both under the assumption of statistical independence and with consideration of correlation between selected variables. The sensitivity analysis is carried out to provide clear insight into the influence of uncertainty in the input parameters on the reliability of the considered limit state. The proposed framework provides a more realistic representation of structural safety and supports data-driven, performance-based management of concrete infrastructures.