Experiments and FEA based safety factor calibration for SFRRAC beams

The objective of this research is to predict the design resistance of steel fibre reinforced recycled aggregate concrete (SFRRAC) beams using a statistical and probabilistic method. SFRRAC is a combination of recycled aggregate concrete (RAC) and steel fibres (SF). It is a sustainable and feasible alternative to natural aggregate concrete (NAC). Because existing structural design standards only provide design equations for NAC members, new design equations and corresponding capacity factors for SFRRAC members need to be developed. In this study, design resistance of SFRRAC beams is estimated based on a proposed resistance prediction model and an associated capacity factor. The capacity factor is calibrated based on the method provided in Eurocode 0 and the target reliability index given in ISO 2394:1998. However, the method is significantly modified to incorporate both experimental data and finite element analysis (FEA) results to estimate the model error of the resistance prediction model. The calibration utilizes recent flexural failure test data for 10 SFRRAC beams together with FEA results. Combining FEA results and experimental data increases the total number of data points and reduces the uncertainty due to a finite number of samples. However, at the same time, the inclusion of FEA results also adds their model uncertainties. The proposed method systematically selects the optimal number of FEA results to be combined with experimental data by considering the optimal balance between the reduced uncertainty due to the FEA data point addition and the increased uncertainty from FEA's model uncertainties.