Influence of variations in concrete material properties on the serviceability of reinforced and prestressed concrete flexural members

The effect of statistical variance associated with concrete material properties for different concrete mixes, curing conditions and ages are reported in this paper. The concrete mixes that were analysed are the commonly used Australian N32 and N40 mixes. Samples of concrete were extracted from concrete trucks on site to ensure that the concrete had been exposed to batching and transport processes associated with typical concrete supply. Curing times for test samples ranged from 7 to 28 days. The test frequency was significantly increased for testing samples at 7 and 28 days due to their importance as commonly referenced values in design. Variations of recorded material properties with respect to time and curing conditions are established via a statistical analysis. A Monte Carlo simulation, incorporating the statistical parameters of material properties as input, was applied to serviceability deflection predictions. A statistical prediction of member deflection was established and analysed depending on the variability of material properties. This paper presents an alternative approach to predicting deflections based on the variability that occurs with concrete material properties.